WO2021018675A1

WO2021018675A1 - Contra flow channel battery heat exchanger

Info

Publication number: WO2021018675A1
Application number: PCT/EP2020/070589
Authority: WO
Inventors: Charles Penny; Adrian Fernandez; Ragu Subramanyam
Original assignee: Senior Uk Limited
Priority date: 2019-08-01
Filing date: 2020-07-21
Publication date: 2021-02-04
Also published as: GB2586058A; GB201910969D0

Abstract

There is disclosed a heat exchanger for regulating the temperature of a battery pack. The battery pack comprises at least one array of battery cells arranged in a row. An end surface of each battery cell lies adjacent the outer surface of a heat exchanger core so that the end surface lies opposite at least a pair of channels, and suitably at least one first fluid channel carrying fluid at a first direction and at least one second fluid channel carrying fluid in a second opposite direction. The heat exchanger may have inlet and outlet fluid connections located at the same end, or at opposite ends of the heat exchanger core. First and second end housings connect at first and second ends of the heat exchanger core. A plurality of partition walls within the manifolds determine the flow path of fluid within the heat exchanger core.

Description

CONTRA FLOW CHANNEL BATTERY HEAT EXCHANGER

Field of the Invention

[0001] The present invention relates to heat exchangers for regulating the temperature of electrical energy cells.

Background of the Invention

[0002] The performance of various kinds of electrical devices— such as transistors, circuit components, integrated circuits, and batteries— often directly correlates with temperature. In general, an increase in temperature causes an increase in impedance in conductors and semiconductors which in turn can lead to an even greater production of heat. This heat impedance feedback loop is well known. To reduce or maintain a level of heat, devices that produce heat are commonly cooled by heat sinks, fans, or liquid cooling apparatuses. Some systems include temperature probes that monitor for overheating and, if detected, intentionally throttle down performance or shut down the device entirely to prevent permanent damage.

[0003] Likewise, the performance and product lifetime of some batteries can be affected by the temperatures generated by those batteries, both in the short-term and long-term. In some types of battery, stored energy is discharged through electrochemical reactions, the rate of which depends in part upon the temperature of the electrodes and electrolyte of the battery, according to the well-known Arrhenius equation. Additionally, excessive heat can cause a degradation in the electrolytes of many types of rechargeable batteries, thereby reducing a battery’s life span and maximum charge capacity. Like semiconductor devices, batteries can also experience heat runaway if the temperature of the battery exceeds a catalyst temperature, which can lead to fire or explosion.

[0004] Conversely, at lower temperatures batteries function sub-optimally, such that increasing their temperature would result in improved performance. Thermal gradients across a battery cell can also have a negative impact on a battery’s performance and longevity. For instance, an intra-cell temperature gradient can affect the diffusion and charge transfer reaction process in rechargeable batteries, such as in lithium ion batteries. Additionally, differences in temperature across a single battery cell can result in an increase in battery impedance, which in turn may lead to the production of more heat as energy is dissipated through that impedance.

[0005] In some applications, multiple batteries or battery cells are electrically connected to each other in series or parallel. Temperature differences between batteries or battery cells within a pack can also reduce the performance of the entire pack— even if the temperatures in each battery or cell are within a nominal operating temperature range. In systems that rely heavily on battery pack performance (e.g., electric vehicles), it is desirable to have a battery pack that can withstand rapid charging and discharging. However, temperature differences across batteries or battery cells in a pack, even by a few degrees Celsius, might render the performance of the entire pack inadequate for some applications.

[0006] The known effects of high temperatures, temperature gradients, and temperature differences within electronic devices, and across battery cells, has led to the development of cooling and heat management systems for such devices and batteries. Passive cooling mechanisms, such as heat sinks, are typically insufficient for high performance applications. Active cooling mechanisms that utilize forced air cooling (e.g. using air circulation fans) or circulated liquid cooling are more common in systems that generate substantial amounts of heat, or are otherwise crippled by overheating. Often, passive components such as heat sinks and high thermal conductivity paste are coupled with active cooling elements in thermal management systems, in order to achieve a greater amount of cooling. A traditional liquid-cooling thermal management system includes a thermally conductive element in direct or proximate contact with the object to be cooled (e.g., a metal plate or heat sink), which draws heat from the object. That thermally-conductive element is in thermal contact with a coolant, either directly (e.g., as the outer surface of a liquid coolant conduit) or indirectly (e.g., in contact with a separate liquid coolant conduit), thereby drawing heat from the thermally-conductive element. The warmed/cooled liquid coolant then flows to a heat exchanger or a heater, such as a radiator or electrical heater, which regulates the temperature of the liquid coolant before recirculating the liquid coolant back toward the thermally-conductive element. Traditional liquid temperature control systems, which are often more effective at transferring heat from/to an object compared to air-cooled systems, may not adequately address the above-described issues arising from temperature gradients within battery cells and temperature differentials across battery cells. For instance, the level of cooling in traditional liquid cooling systems is often not uniform across a given surface area. As liquid coolant flows from an inlet toward an outlet, it accumulates heat, thereby rendering the liquid near the coolant outlet warmer than liquid near the inlet. This temperature gradient in the liquid coolant itself can result in a corresponding temperature gradient across the object being cooled. The liquid coolant temperature gradient can also lead to a temperature differential between two objects being cooled by the same system. Such uneven cooling can substantially reduce the performance of a battery pack, can reduce the longevity of the battery pack, and in some cases can be dangerous as localized impedances and degradations build up in the battery cells over time.

[0007] One known technique for reducing the severity of temperature gradients across a surface of a circulated coolant-type heat exchanger involves providing a set of channels in a counter-flow or“countercurrent” arrangement. In a counter-flow heat exchanger, a set of “cold” fluid channels, with fluid flowing in one direction, are interlaced with and in thermal connection with a set of “warm” fluid channels with fluid flowing in the opposite direction. The“cold” fluid channels may receive liquid coolant supplied from an inlet, whereas the“warm” fluid channels may receive liquid coolant supplied (or recirculated) from the“cold” channels. In such an arrangement, alternating the“hot” and“cold” channels serves to reduce temperature gradients along the coolant flow direction (from a manifold side to a recirculation side of the heat exchanger).

[0008] While counter-flow channel designs can mitigate temperature gradients, the temperature gradients across a typical counter-flow heat exchanger may still be too large for some applications. It is therefore an object of the present invention to provide heat exchangers capable of providing both effective and substantially uniform cooling across its heat-exchanging surface area.

[0009] In addition, it is often desirable to provide a low-profile battery pack that can fit into smaller spaces. In electric vehicles, for example, battery packs are commonly located as low as possible, beneath the passenger cabin— rather than in the trunk / boot or under the hood / bonnet in order to improve the safety and handling of the vehicle. One goal of battery pack design may be, therefore, to minimize the size of the thermal management system along one or more dimensions to thereby provide the maximum amount of space for the batteries— all within a relatively small assembly. It is therefore another object of the present invention to provide heat exchangers that are capable of providing substantially uniform cooling, while simultaneously being shallow, thin, low-profile, or otherwise limited in size along at least one axis of dimension.

[0010] In some applications, multiple countercurrent-type heat exchangers may be arranged in a compact configuration (e.g., so as to fit within an assembly or enclosure). Depending on the particular arrangement, some heat exchangers may be oriented differently from other heat exchangers, to accommodate other structural elements, reduce the total amount of space taken up by the heat exchangers, and/or for other various reasons. Different orientations of heat exchanger may give rise to different rates of heat exchange for otherwise nominally similar heat exchangers. One solution to this problem may involve the construction of similar, but distinct, heat exchanger designs corresponding to each respective orientation. However, providing multiple heat exchanger designs may substantially increase the cost of development, testing, and manufacturing the multi-heat exchanger arrangement. It is therefore another objective of the present application to provide heat exchangers that are modular, of a like component construction that is repositionable and re-orientable.

[0011] In some embodiments of the invention, a pair of coolant fluid ports can interchangeably serve as a coolant inlet and a coolant outlet for the heat exchanger. Coolant may flow in the direction from one port to the other, or in the reverse direction, with both coolant flow directions providing substantially the same temperature regulation effectiveness.

[0012] The temperature of an electric car battery significantly affects how well it performs. Current state-of-the-art electric car batteries typically work best within a temperature range of 15 to 30°C. For electric vehicles which may be sold across multiple markets the battery thermal management system must keep the batteries within a defined temperature range throughout a wide range of different climates ranging from colder climates through to hot climates.

[0013] In modern electric vehicles, heating the battery packs up to the optimum working temperature is just as important as keeping the battery cooled. Known thermal management systems may harvest energy generated anywhere in the vehicle, for example in the power electronics or in the motors and that energy can be used either to thermally regulate the temperature of the battery pack, and/or to regulate the temperature of the interior passenger compartment.

[0014] The battery pack in a known electric vehicle typically comprises a collection of relatively small lithium ion cells arranged in rows and columns. The cells are connected in a combination of series and parallel to produce the required power output and voltage. Known battery cooling systems comprise a series of metallic channels interspersed between rows of batteries, with a liquid coolant such as glycol being passed through the metallic channels. The coolant channels pass between or under the individual cells. By using many small cells instead of a few larger cells, a more even temperature regulation across a battery pack can be achieved. This reduces temperature hotspots and leads to longer battery life.

[0015] For example, in the known Tesla Model S and other Tesla electric vehicles, a plurality of individual substantially circular cylindrical battery cells are arranged in a forest or crowd type arrangement standing side-by-side on end with their cathodes lower than their anodes. The individual cells are arranged in rows and columns standing upright. [0016] Referring to Figure 1 herein, there is illustrated schematically in perspective view from above and one side and arrangement of a Tesla battery pack comprising 7 pairs of rows of individual lithium ion battery cells.

[0017] Referring to Figure 2 herein, there is shown the Tesla battery pack of Figure 1 in plan view.

[0018] Within each layer of rows, individual battery cells of a first row are interleaved with individual battery cells of a second row, so as fit the two rows into as small a volume as possible.

[0019] In each battery pack, a single cooling plate is fitted between adjacent pairs of battery cells, with liquid coolant introduced at one end of the battery pack via an inlet port and being returned at the same end of the battery pack via a liquid coolant outlet port. In the Tesla arrangement, the single heat exchanger core is arranged within the battery pack in a substantially “S” shaped path between the circular cylindrical faces of the individual lithium ion battery cells, so that each individual lithium ion battery cell has at least part of its outer surface adjacent the core of the heat exchanger. Details of the arrangement are shown in for example US 8758924 B1.

[0020] The cells are arranged as detachable modules, which are typically located low down in the vehicle, for example on the floor pan, to give low center of gravity and to avoid intruding into passenger compartment space or luggage.

[0021] Batteries generate the most heat when they are experiencing maximum current flow, which is typically either when charging, or under conditions of high discharge, for example fast acceleration, when the vehicle fully loaded with passengers, and/or when the vehicle is carrying a heavy weight or towing.

[0022] Ongoing engineering objectives for heat exchangers for thermal control of battery packs electric vehicles include optimising thermal performance so that the heat exchanger can heat and cool a battery pack; reducing weight so as to improve vehicle range; making the heat exchanger compact so as to reduce size and therefore include more battery cells in a given space; reducing required fluid pressure so that a smaller pump can be used which is more compact and takes less energy to run; improving ease of manufacture; improving reliability and increasing the minimum design life; and reducing cost. These objectives could also be applied to stationary battery packs.

[0023] These and other objectives and advantages of the present invention will become apparent from the following detailed written description, Figures, and claims.

Summary of the Invention

[0024] Each heat exchanger herein comprises a heat exchanger core and a first end housing which locates on a first end of the heat exchanger core. Various embodiments comprise a second end housing which locates on the second end of the heat exchanger core.

[0025] Fluid inlets and outlets which connect an external heat exchange fluid circuit to the heat exchanger may be provided on the first end housing only, on the second end housing only, or on the first and second housings depending on the internal flow path configuration within the heat exchanger core and depending upon the layouts of an external heat management circuit to which the heat exchanger is to be connected, and whether this requires fluid inlet and outlet in close proximity at one end of the heat exchanger, or a fluid inlet and a fluid outlet at opposite ends of the heat exchanger.

[0026] In the best mode embodiments, the heat exchanger core may be extruded and cut or machined to an appropriate length, with the first and/ or second end housings providing the external fluid connections to the external heat management circuit of an electric vehicle, and determining the internal flow path of heat exchange fluid within the central heat exchanger core.

[0027] In the best mode embodiments, the end housings may comprise one or a plurality of manifolds. A said end housing may comprise:

• a chamber which communicates a fluid path between an externally connectable fluid inlet pipe and one or more fluid channels within said heat exchanger core;

• a chamber which communicates a fluid path between an externally connectable fluid outlet pipe and one or more fluid channels within said heat exchanger core; • a chamber which communicates one or more fluid paths between a first set of channels of said heat exchanger core and a second set of channels of said heat exchanger core.

[0028] Each end housing may comprise one or more manifolds.

[0029] Preferably one or more said end housings determines the flow path of heat exchange fluid within the heat exchanger core. Within the heat exchanger there may be various flow paths including:

• One or more“U” shaped flow paths each comprising one traverse of the heat exchanger core in a first direction along a first channel or first set of channels, and one traverse of the heat exchanger core in a second, opposite direction along a second channel or a second set of channels; wherein the flow direction in the first channel or first set of channels is opposite to the flow direction in the second channel or second set of channels.

• One or more“S” shaped flow paths, each comprising one traverse of the heat exchanger core in a first direction along a first channel or a first set of channels, one traverse of the heat exchanger core and a second, opposite direction along a second channel or a second set of channels, and one further traverse of the heat exchanger core in said first direction along a third channel or a third set of channels, wherein a flow direction along the first and/or third channels is opposite to a flow direction in the second channel or second set of channels.

[0030] Each heat exchanger core comprises a first sidewall having a first outer heat exchange surface; a second side wall, which may or may not have a second outer heat exchange surface; said first and second side wall spaced apart from each other; a plurality of partition walls, each partition wall extending between said first and second side wall; a plurality of fluid channels each defined between an inner surface of said first side wall, and in a surface of said second side wall, and a respective surface of each of a pair of adjacent said partition walls.

[0031] Each heat exchanger core has a first end; a second end; said first and second sidewalls extending between said first and second ends; a width, said first and second sidewalls extending across said width; and a thickness, said thickness being between said first outer heat exchange surface and said second outer heat exchange surface. A plurality of said channels each extending between said first and second ends and arranged side-by-side across said width of said heat exchanger core.

[0032] According to a first aspect of the present invention, there is provided a heat exchanger for regulating the temperature of a battery pack; said heat exchanger comprising:

a heat exchanger core comprising:

a first side wall having an outer heat exchange surface;

a second side wall having an outer heat exchange surface;

a plurality of connecting walls positioned between said first and second side walls, said connecting walls and said first and second side walls defining a plurality of elongate channels each extending between said first and second ends of said heat exchanger; and

a first end housing comprising:

a first side wall;

a second side wall; and

a plurality of internal wall structures, said internal wall structures arranged to seal against said plurality of connecting walls to partition said plurality of elongate channels into a first set of channels for carrying fluid in a first direction, and a second set of channels for carrying fluid in a second direction, said second direction being opposite to said first direction;

wherein each first channel of said first set of channels lies immediately adjacent to a second channel of said second set of channels.

[0033] Preferably, each first channel of the first set of channels is separated from a second channel of the second set of channels by a said connecting wall, such that heat may transfer through the connecting wall between fluid flowing in the first channel in the first direction, and fluid flowing in the second channel in the second direction, where the first and second directions are opposite to each other. [0034] Suitably, the outer heat exchange surfaces act as cooling surfaces to cool the ends of battery cells or heat sinks.

[0035] Preferably a maximum temperature range between a hottest temperature on a said outer heat exchange surface and a lowest temperature on said outer heat exchange surface is 60% or lower than a maximum temperature range between a corresponding hottest temperature on said outer heat exchange surface and a corresponding lowest temperature of said outer heat exchange surface where said heat exchanger core is connected for a single pass end to end flow of said fluid in a single direction across said heat exchanger core.

[0036] Preferably said first side wall comprises an end face;

said second side wall comprises an end face;

each of said plurality of connecting walls comprises a corresponding respective connecting wall end face;

each of said internal wall structures of said end housing comprises a corresponding respective internal wall end face; and

wherein said end faces of said internal wall of said end housing face opposite to said end faces of said first side wall, said second side wall and said plurality of connecting walls.

[0037] Said end housing may comprise a separately manufactured component to said heat exchanger core.

[0038] Preferably said heat exchanger core comprises an extruded component which has a same cross-sectional profile in a plane perpendicular to a main length direction, at all positions along a whole length of said heat exchanger core.

[0039] Preferably the end housing is constructed such that one end of said end housing fits over an end of said heat exchanger core.

[0040] The end housing preferably comprises a mouth or aperture into which one end of the heat exchanger core closely fits, such that the individual channels of the heat exchanger core align with a plurality of apertures recessed inside the main body of the end housing, the apertures connecting with one or more chambers or manifolds in an end housing.

[0041] Said end housing may be attached to said end of said heat exchanger core by an epoxy adhesive.

[0042] Preferably said plurality of connecting walls of said end housing define a plurality of apertures, each said aperture communicating with a chamber within a said manifold.

[0043] According to a second aspect there is provided a heat exchanger for regulating the temperature of a battery of electrical energy cells, and with the coolant flowing in an S pattern, said heat exchanger comprising:

a heat exchange core;

a first end housing having a fluid inlet tube; and

a second end housing having a fluid outlet tube;

said heat exchange core comprising a first side wall, a second side wall, and a plurality of channels positioned and extending between said first and second side walls,

said heat exchange core having a first end and a second end;

each said channel extending along a length of said heat exchange core between said first and second ends;

said channels comprising a first plurality of channels and a second plurality of channels, wherein said first plurality of channels are interleaved with said second plurality of channels such that each said second channel lies adjacent to at least one said first channel;

said first end housing being arranged to connect said fluid inlet tube with said a number of first plurality of channels to distribute fluid into a number said first plurality of channels; and

said second end housing being arranged to connect said a number of first plurality of channels with a second plurality of channels; wherein a fluid flow direction in said first plurality of channels is opposite to a flow direction in said second plurality of channels; and said second plurality of channels return the fluid flow to the first end housing

said first end housing being arranged to connect said second plurality of channels to a further number of first plurality of channels and said further number of first channels return the flow to the second end housing

said second end housing being arranged to connect said further number of first plurality of channels with said fluid outlet tube to transfer flow from further first plurality of channels to said fluid outlet tube.

[0044] Preferably said first end housing comprises:

a first outer shell component;

a second outer shell component;

a partition member located between said first outer shell and said second outer shell;

said partition member dividing a space between said first outer shell and said second outer shell into a first cavity and a second cavity;

said partition member comprising a first plurality of wall formations for directing fluid between said first cavity and said number of first plurality of channels; and

said partition member comprising a second plurality of wall formations for directing fluid between said second plurality of channels and said second cavity to said further number of first plurality of channels.

[0045] Preferably said first plurality of wall formations are arranged to seal across a plurality of connecting walls extending between said first sidewall and said second sidewall of said heat exchanger core.

[0046] Preferably said first end housing and said second end housing are formed by said first outer shell component, said second outer shell component and said partition member.

[0047] According to a third aspect there is provided a heat exchanger for regulating the temperature of a battery of electrical energy cells, and with the coolant flowing in an U pattern said heat exchanger comprising: a first end housing comprising of

a first manifold for the inlet of a flow of heat exchange fluid, said first manifold comprising a heat exchange fluid inlet;

a second manifold for the outlet of a flow of heat exchange fluid, said second manifold comprising a heat exchange fluid outlet;

and a second end housing comprising of a single chamber

a heat exchange core comprising:

a plurality of first fluid channels each extending between said first inlet manifold and said second end housing, said first fluid channels for carrying heat exchange fluid in a first direction; and

a plurality of second fluid channels each extending between said second end housing and said second outlet manifold, said second fluid channels for carrying heat exchange fluid in a second direction, wherein said second direction is opposite to said first direction;

a first sidewall and a second side wall;

a plurality of connecting walls each extending between said first side wall and said second side wall, said plurality of connecting walls partitioning a space between said first and second sidewalls into a plurality of said first and second channels such that as viewed in a direction perpendicular to a main plane of a said first and/or second said side walls, said first and second channels are arranged side-by-side with respect to each other;

said plurality of first channels and said plurality of second channels being arranged across said core, such that each said first channel is bounded by at least one said second channel, and each said second channel is bounded by at least one said first channel;

said first inlet manifold comprising a plurality of passageways for distributing a flow of heat exchange fluid between said heat exchange inlet and said plurality of first fluid channels; said second outlet manifold comprising a plurality of passageways for receiving said flow of heat exchange fluid from said plurality of second fluid channels and said outlet.

[0048] Preferably said first end housing comprises:

a first outer shell defining a first cavity;

a first heat exchange fluid tube having one end opening into said first cavity; a second outer shell defining a second cavity;

a second heat exchange fluid tube having one end opening into said second cavity

an inner wall component located between said first and second outer shells said inner wall component separating said first and second cavities;

said inner wall comprising a plurality of first apertures defining a plurality of first channels and a plurality of second apertures defining a said plurality of said second channels.

[0049] In some embodiments, said first outer shell and said second outer shell may be substantially identical to each other.

[0050] Preferably said inner wall component comprises a separate component to said first or second outer shell.

[0051] Preferably said heat exchange core comprises:

a first side wall plate;

a second side wall plate;

an upper plate connecting an upper end of said first side wall plate with an upper end of said second side wall plate;

a lower plate connecting a lower end of said first side wall plate with a lower end of said second side wall plate;

said first side wall plate being spaced apart from and lying opposite from said second side wall plate;

said plurality of connecting walls each extending between said first side wall plate and said second side wall plate, said plurality of connecting walls partitioning a space between said first and second sidewalls into said plurality of channels such that as viewed in a direction perpendicular to a main plane of a said first and/or second said side wall, said channels are arranged side-by-side with respect to each other.

[0052] Said heat exchanger core may be formed as an extrusion.

[0053] According to a fourth aspect there is provided a heat exchanger for regulating the temperature of a plurality of electrical energy cells, said heat exchanger comprising:

a heat exchange core having a first end, a second end, a first side wall and a second side wall, said first and second side walls extending between said first and second ends;

a plurality of first flow channels extending along a main length of said heat exchange core between said first and second ends;

a plurality of second flow channels extending along a main length of said heat exchange core between said first and second ends;

wherein the flow direction of said first flow channels is opposite to the flow direction of said second flow channels; and

an outer surface of said first side wall of said heat exchange core may be imagined to be partitioned into a plurality of partition areas, each said partition area corresponding to an end area of row of one end of a said electrical energy cells; and

an inner surface of said first side wall may be imagined to be partitioned into a second plurality of partition areas, each said second partition area coinciding with a corresponding respective said first partition area, wherein each said second partition area forms an inner wall of at least one said first channel and at least one said second channel or if S flow at least one said first channel and at least one said further first channel.

[0054] Preferably each said partition area corresponds with the area occupied by an outer end surface of an individual row of electrical energy cells.

[0055] According to a fifth aspect there is provided a battery apparatus comprising a battery pack and a heat exchanger; said battery pack comprising a first plurality of battery cells arranged in at least one row;

each said battery cell having body, said body having first and second ends; each of said first ends lying on the first end plane, and each of said second ends lying a second end plane such that a said first or second end plane lies across a main length direction of each said battery cell;

said heat exchanger comprising:

a first end and a second end;

a plurality of first fluid channels each extending between said first end and said second end , said first fluid channels carrying heat exchange fluid in a first direction; a plurality of second fluid channels each extending between said first end and said second end , said second fluid channels carrying heat exchange fluid in a second direction, wherein said second direction is opposite to said first direction; each said first channel lies next to a said second channel and is separated therefrom by an intervening wall between said first and second channels;

an outer heat exchange surface which lies substantially on a first plane;

said outer heat exchange surface being positioned adjacent said row of battery cells, such that one end of each said battery cell has a thermal path to said outer heat exchange surface of said heat exchanger;

wherein each said battery cell describes and area footprint projecting from a perimeter area of said end of said battery cell in a direction towards said heat exchanger, and which projects on to said outer heat exchange surface;

wherein each said area footprint projects in a direction perpendicular to said first plane through at least one said first fluid channel and through at least one of said second fluid channel or if S flow at least one said first channel and at least one said further first channel.

[0056] According to a sixth aspect there is provided an end housing for a heat exchanger, said end housing comprising:

a first outer shell component;

a second outer shell component; a partition member located between said first outer shell and said second outer shell;

said partition member dividing a void between said first outer shell and said second outer shell into a first cavity and a second cavity;

said partition member comprising a first plurality of wall formations forming a first plurality of apertures;

said first plurality of wall formations forming a first plurality of channels for directing fluid between said first cavity and said first plurality of apertures;

said partition member comprising a second plurality of wall formations forming a second plurality of apertures;

said second plurality of wall formations forming a second plurality of channels for directing fluid between said second cavity and said second plurality of apertures; wherein each said first channel lies adjacent to at least one said second channel.

[0057] According to a seventh aspect there is provided a heat exchanger core comprising:

a first side wall;

a second side wall;

a plurality of connecting walls extending between said first and second side walls, said connecting walls and said first and second side walls defining a plurality of elongate channels each extending between said first and second ends of said heat exchanger;

said core having a first end and a second end;

said first side wall, said second side wall, and each of said plurality of connecting walls extending fully between said first and second ends, such that each of said plurality of channels are open at said first end and are open at said second end.

[0058] Preferably said first side wall comprises a first end face at said first end of said core; said first side wall comprises a second end face at said second end of said core;

said second side wall comprises first end face and said first end of said core; said second side wall comprises a second end face and said second end of said core;

each said connecting wall comprises a corresponding respective first end face at said first end of said core; and

each said connecting wall comprises a corresponding respective second end face at said second end of said core.

[0059] Preferably each of said end faces lie on a plane which is perpendicular to a main plane which bisects each of said plurality of elongate channels.

[0060] In some embodiments, said plurality of channels are arranged in parallel in a single layer across a main width of said heat exchanger core;

said channels comprising a plurality of inner most channels, each innermost channel having a first cross-sectional area in a direction perpendicular to a main length of said channel; and

said channels comprising at least one outer most channel, located at said side of said heat exchanger core, said outermost channel having a cross-sectional area in a direction perpendicular to a length of said channel which is smaller than a cross- sectional area of a said innermost channel.

[0061] Said heat exchanger core may comprise an extruded component which has a same cross-sectional profile in a plane perpendicular to a main length direction, at all positions along a whole length of said heat exchanger core.

[0062] At least one said connecting wall may comprise one or a plurality of fins structures having a base portion attached to said at least one connecting wall, and a tip portion which extends into a cavity of a said elongate channel.

[0063] In one embodiment there is provided a battery apparatus comprising a battery pack and a heat exchanger;

said battery pack comprising a first plurality of battery cells arranged in a stack; said stack comprising a plurality of rows of said battery cells; each said battery cell having a cathode electrical contact and an anode electrical contact, and having a main length which extends between and through said cathode contact and said anode contact;

within each said row, each battery cell lies with a first anode end on a first side of said stack and a second cathode end on a second side of said stack;

said heat exchanger comprising:

a fluid inlet and a fluid outlet;

a plurality of first fluid channels each extending between said inlet and said outlet, said first fluid channel to carrying heat exchange fluid in a first direction;

a plurality of second fluid channels each extending between said inlet and said outlet, said second fluid channels carrying heat exchange fluid in a second direction, wherein said second direction is opposite to said first direction;

an outer heat exchange surface which lies substantially on a first plane;

said outer heat exchange surface being positioned adjacent a said side of said stack such that said first plane lies across a main length direction of each said battery cell and such that one end of each said battery cell has a thermal path to said outer heat exchange surface of said heat exchanger;

wherein each said battery cell describes and area footprint projecting from a perimeter area of said anode or cathode in a direction towards said heat exchanger, and which projects on to said outer heat exchange surface;

wherein each said area footprint projects through at least one said first fluid channels and through at least one of said second fluid channels.

[0064] In some embodiments there is provided a battery apparatus comprising a battery pack and a heat exchanger;

said battery pack comprising a first plurality of battery cells arranged in at least one row;

each said battery cell having body and first and second ends;

a cathode electrical contact and an anode electrical contact, and having a main length which extends between and through said cathode contact and said anode contact; within each said row, each battery cell lies with a first anode end on a first side of said stack and a second, cathode end at a second side of said stack;

said heat exchanger comprising:

a fluid inlet and a fluid outlet;

an outer heat exchange surface which lies substantially on a first plane;

[0065] In the above embodiments, the end housings and/or heat exchanger core may be formed of a high thermal conductivity plastics material.

[0066] Other aspects are as set out in the claims herein, the content of which are incorporated into this summary by reference.

Brief Description of the Drawings

[0067] For a better understanding of the invention and to show how the same may be carried into effect, there will now be described by way of example only, specific embodiments, methods and processes according to the present invention with reference to the accompanying drawings in which: Figure 1 shows schematically in perspective view from above and one side a generic layout of a prior art battery pack comprising a plurality of rows of pairs of individual battery cells, having a passageway there - between;

Figure 2 shows schematically the prior art battery pack of Figure 1 in view from above;

Figure 3 shows schematically a battery pack comprising first and second stacks, each stack comprising a plurality of battery layers, each battery layer comprising a plurality of individual battery cells;

Figure 4 shows in view from one side the battery pack of Figure 3 herein;

Figure 5 shows schematically the battery pack of Figures 3 and 4 in view from above, showing first and second stacks arranged side-by-side with a gap or spacing there-between;

Figure 6 shows schematically the battery pack of Figure 3 in view from one end;

Figure 7 shows schematically a first heat exchanger according to a first specific embodiment of the invention;

Figure 8 shows the first heat exchanger of Figure 7 placed in a battery pack between first and second stacks of batteries for regulating the temperature of the ends of the layers of batteries and the ends of the individual battery cells within the layers;

Figure 9 shows a second battery pack showing a second arrangement of batteries arranged in two stacks placed side-by-side with a central passageway there-between, each stack comprising a plurality of layers, and each layer comprising a plurality of individual battery cells;

Figure 10 shows the second battery pack in view from one side;

Figure 1 1 shows the second battery pack in view from above, illustrating a side- by-side arrangement of first and second stacks, having a central passageway there between;

Figure 12 shows the second battery pack in view from one end;

Figure 13 shows the first heat exchanger positioned in a central passageway of the second battery pack for regulating the temperature of the second battery pack; Figure 14 shows the first heat exchanger in view from one side;

Figure 15 shows the first heat exchanger in view from above;

Figure 16 shows the first heat exchanger in perspective view with a first end housing removed;

Figure 17 shows the first heat exchanger in perspective view with the first end housing removed, showing the positioning of internal fluid channels with respect to the placement of individual battery cells adjacent a core of the heat exchanger;

Figure 18 shows one end of the first heat exchanger core in perspective view with the first end housing removed, and showing the positioning of the ends of individual battery cells with respect to internal channels within a heat exchanger core of the first heat exchanger;

Figure 19 shows the first heat exchanger core in view from one end;

Figure 20 shows in cut away view from one side the central core section of the first heat exchanger, having a second end housing connected at a second end, but absent a first end housing;

Figure 21 shows the first heat exchanger core and a second end housing of the first heat exchanger in cut away view from one side showing a plurality of channels running lengthwise in parallel along the heat exchanger core;

Figure 22 shows a first end housing having an inlet/outlet manifold of the first heat exchanger in perspective view;

Figure 23 shows the first end housing in exploded view from above and one side;

Figure 24 shows the first end housing in exploded view from above and from another, opposite side;

Figure 25 shows the first end housing in view from one end, showing internal passage ways for directing or receiving coolant fluid into or from the central core of the heat exchanger;

Figure 26 shows the first end housing in view from one side; Figure 27 shows in perspective view from above and one side a second end housing comprising a return chamber beatable at a second end of the heat exchanger core of the first heat exchanger;

Figure 28 shows a second heat exchanger according to a second embodiment of the present invention in view from one side;

Figure 29 shows the second heat exchanger in view from above;

Figure 30 shows schematically a first end of a central core section of the second heat exchanger, without any end housing, showing directions of coolant fluid flow within individual channels through the second heat exchanger core, and the positioning of individual coolant channels relative to individual battery cells arranged in rows adjacent sides of the second heat exchange core;

Figure 31 shows the second heat exchange core in cut away view from one end;

Figure 32 shows the second heat exchange core as viewed from the first end, having the second end housing removed;

Figure 33 shows the second heat exchanger core and a return flow manifold in cutaway view from one side;

Figure 34 shows a first end housing of the second heat exchanger in perspective view;

Figure 35 shows the first end housing of the second heat exchanger in exploded view from above and one side;

Figure 36 shows the first end housing of the second heat exchanger in exploded view from above and from another, opposite side;

Figure 37 shows the first end housing of the second heat exchanger in view from one end, showing internal passage ways for directing coolant fluid into the central core of the second heat exchanger;

Figure 38 shows the first end housing of the second heat exchanger in view from above showing a cross-section plane C - C;

Figure 39 shows the first end housing of the second heat exchanger in cut away view from one side along the plane C - C; Figure 40 shows the first end housing of the second heat exchanger in view from above showing a cross-section plane B - B;

Figure 41 shows the first end housing of the second heat exchanger in cut away view from one side along the plane B - B;

Figure 42 shows in cut away view from one end a third heat exchanger core having a plurality of internal fin protrusions inside individual channels of the third heat exchanger core;

Figure 43 shows in cut away view a section of a heat exchange core having fin protrusions on connecting walls dividing individual flow and return channels inside the heat exchanger core;

Figure 44 shows in view from one end the third heat exchange core having fitted a return manifold, but absent of an inlet/outlet manifold;

Figure 45 shows in perspective view a third battery pack comprising two rows of rectangular battery cells arranged in parallel to each other;

Figure 46 shows the third battery pack from one side;

Figure 47 shows the third battery pack in view from above;

Figure 48 shows the third battery pack in view from one end;

Figure 49 shows the third battery pack in perspective view and including a heat exchanger as disclosed herein;

Figure 50 shows a first general flow path arrangement of a heat exchanger disclosed herein, comprising one or a plurality of“U” shaped flow paths;

Figure 51 shows a second general flow path arrangement of a heat exchanger disclosed herein, comprising one or a plurality of“S” shaped flow paths;

Figure 52 shows schematically a single row battery pack comprising a single row of battery cells in thermal contact with a heat exchanger device disclosed herein;

Figure 53 shows schematically in perspective view, a heat exchanger device disclosed herein fitted in a central passageway between two stacks of battery cells, each stack comprising four layers of battery cells; Figure 54 shows schematically in perspective view a fourth heat exchanger according to a fourth specific embodiment, comprising a ten channel“S” flow path heat exchanger;

Figure 55 shows schematically the fourth heat exchanger in view from one end, showing inlet and outlet fluid pipes on a same side of the heat exchanger core;

Figure 56 shows schematically the fourth embodiment heat exchanger in view from one side;

Figure 57 shows schematically the fourth heat exchanger in view from above;

Figure 58 shows schematically in cutaway view along the line N- N the fourth heat exchanger;

Figure 59 shows schematically a first end housing of the fourth heat exchanger;

Figure 60 shows schematically the first end housing of the fourth heat exchanger in exploded view;

Figure 61 shows schematically a second end housing of the fourth heat exchanger;

Figure 62 shows schematically in exploded view the second end housing of the fourth heat exchanger;

Figure 63 shows schematically in perspective view a fifth heat exchanger having an internal fifteen channel“S” flow fluid path;

Figure 64 shows schematically the fifth heat exchanger in view from one end, showing a fluid inlet pipe and a fluid outlet pipe on a same side of said heat exchanger;

Figure 65 illustrates schematically the fifth heat exchanger in view from one side;

Figure 66 illustrates schematically the fifth heat exchanger in view from above;

Figure 67 shows schematically the fifth heat exchanger in cutaway view along the plane 0 - 0 identified in Figure 70 herein;

Figure 68 shows schematically a first end housing of the fifth heat exchanger;

Figure 69 shows schematically the first end housing of the fifth heat exchanger in exploded view; Figure 70 shows schematically a second end housing of the fifth heat exchanger; and

Figure 71 shows schematically the second end housing of the fifth heat exchanger in exploded view;

Figure 72 shows in external view a sixth heat exchanger having a first fluid connector at a first end and a second connector at a second end;

Figure 73 shows in cut away view from one end a heat exchanger core of the sixth heat exchanger, having open sides;

Figure 74 illustrates schematically a first“U” flow path utilising two channels of a heat exchanger core;

Figure 75 illustrates schematically a second“U” flow path using 3 channels in a heat exchanger core;

Figure 76 illustrates schematically a third“U” flow path using 4 channels of the heat exchanger core;

Figure 77 illustrates schematically a fourth“U” flow path using 4 channels of a heat exchanger core;

Figure 78 illustrates schematically a fifth“U” flow path using 4 channels of a heat exchanger core;

Figure 79 illustrates schematically a second“S” flow path using 10 channels of a heat exchanger core;

Figure 80 illustrates schematically in view from one end a core of a seventh heat exchanger having 14 parallel fluid containing channels;

Figure 81 illustrates schematically a planar section G-G bisecting the core of the seventh heat exchanger;

Figure 82 illustrates schematically in cut away view along the plane G - G the core of the seventh heat exchanger, showing an “S” shaped flow path of heat exchange fluid through the core;

Figure 83 illustrates schematically in view along the plane G-G the core of the seventh heat exchanger, showing the“S” shaped flow path of heat exchange fluid through the core in relation to the positioning of a plurality of partition areas on the outer surface of the heat exchanger core which lies immediately adjacent a plurality of battery cell end surfaces;

Figure 84 illustrates schematically in view from one end a heat exchanger core of an eighth heat exchanger having 18 internal channels, each channel having a same cross-sectional area in the direction perpendicular to a main length direction of the core;

Figure 85 illustrates schematically in view from one end, the heat exchanger core of the eighth heat exchanger showing a plane H - H which bisects the heat exchanger core along its length and thickness;

Figure 86 illustrates schematically in view along the plane H - H the core of the eighth heat exchanger, configured to operate with a plurality of“S” shaped flow paths of heat exchange fluid through said core;

Figure 87 illustrates schematically in view along the section plane H - H the core of the eighth heat exchanger showing the plurality of“S” shaped flow paths and showing the positioning of individual channels in relation to a plurality of partition areas, each partition area lying immediately opposite a corresponding respective end surface of a respective battery cell;

Figure 88 shows a temperature contour map of coolant temperatures on an outer surface of a heat exchanger core herein, when in operation with liquid heat exchange fluid flowing end to end through the prior art heat exchanger core, without any fluid contra flow for cooling a battery pack comprising two stacks of batteries each stack comprising 5 layers of batteries each layer comprising 55 individual lithium ion battery cells;

Figure 89 shows a temperature contour map of coolant temperatures on an outer surface of a heat exchange core herein, when in operation with liquid heat exchange fluid flowing in an “S” shaped reciprocating path entering the heat exchanger core at one end, travelling in a flow direction to the opposite end, and then returning in a contraflow, return direction and then back in the flow direction towards the opposite end; and Figure 90 shows schematically a temperature key for interpreting Figures 88 and 89 herein, in which a difference in temperature ranges between the heat exchanger cores of Figures 88 and 89 are compared.

Detailed Description of the Embodiments

[0068] There will now be described by way of examples several specific modes of the invention as contemplated by the inventors. In the following description numerous specific details are set forth in order to provide a thorough understanding. It will be apparent however, to one skilled in the art, that the present invention may be practiced without limitation to these specific details. In other instances, well known methods and structures have not been described in detail so as not to unnecessarily obscure the description.

[0069] In this specification, the term battery cell is used to describe a smallest unit of an electrical energy cell having an anode and cathode and which is self- contained, discreet and separate from any other battery cell. A battery cell can comprise for example a known electrochemical rechargeable cell. Typically each battery cell has a first end, a second end, and an outer body surface extending between the first and second ends. The anode and cathode may be located on the same end, or on opposite ends of the battery cell. The outer body may have a substantially rectangular outer surface extending between the first and second ends or may have a substantially cylindrical outer surface extending between the first and second ends.

[0070] In this specification, the term battery pack is used to refer to a plurality of one or more individual battery cells, arranged such that the plurality of anodes of the battery cells are connected together by a common electrical anode connector bus, and the plurality of cathodes of the cells are connected together by a common electrical cathode connector bus.

[0071] In the specification, the example of temperature control of Lithium Ion battery cells is described. It will be understood by the person skilled in the art that the embodiments and techniques described herein may also, apply to various like battery types used in or suitable for use in electric vehicles such as sodium nickel chloride (Na - NiCI₂); nickel metal hydride (NI-MH); and / or lithium Sulphur (LI - S), and the description herein includes those types of battery cell.

[0072] Referring to Figures 3 to 6 herein, there is illustrated schematically a general layout of a battery pack comprising a plurality of layers, each layer comprising a plurality of individual battery cells, in which there are 2 stacks of layers spaced apart from each other by a central aisle.

[0073] Referring to Figure 3 herein, there is illustrated schematically in perspective view from above and one side a general layout of an individual battery pack 300 for an electric vehicle. The battery pack comprises a plurality of individual battery cells (not shown in Figure 1) which are arranged side-by-side in layers 301 - 310, each layer comprising a row of individual battery cells arranged side-by-side. The individual layers are arranged in first and second stacks 311 , 312, said first and second stacks being arranged side-by-side with a passageway or cavity 314 there between, separating said first and second stacks.

[0074] Referring to Figure 4 herein, there is illustrated schematically in view from one side, the battery pack of Figure 1 herein, showing first stack 31 1.

[0075] Referring to Figure 5 herein, there is illustrated schematically in plan view from above the battery pack 300 of Figure 3 herein shown, showing first stack 311 and second stack 312.

[0076] Referring to Figure 6 herein, there is illustrated schematically in view from one end the battery pack of Figure 1 showing first and second stacks 311 , 312 and showing a passageway, or aisle 313 between said first and second stacks of battery cells.

[0077] In the example shown in Figures 3 to 6 herein, first stack 311 comprises a first set of five individual layers 301 - 305 of cells, and second stack 312 comprises a second set of individual layers 306 - 310 of cells. Although the layers in Figure 3 are shown as rectangular layers, within each layer are a plurality of battery cells arranged in a row side-by-side, for example a plurality of circular cylindrical battery cells, the battery cells all having their respective cathodes facing outwardly of the battery pack on an outer face of the battery pack, and the plurality of battery cells each having their individual anode pointing inwardly towards the centre of the battery pack.

[0078] Similarly, second stack 312 in the example shown comprises five individual layers of battery cells, each layer comprising a row of battery cells. Within each row or layer each of the plurality of individual battery cells in the second stack have anodes pointing inwardly towards the centre of the battery pack, and their cathodes facing outwardly on the other side of the battery pack, so that as viewed from outside the battery pack, the cathodes of the individual battery cells are at or near the outer perimeter of the battery pack and the anodes of the plurality of battery cells are substantially in the centre of the battery pack, arranged either side of the central aisle or spacing between the first and second stacks.

[0079] In the arrangement shown, in use, the central region of the battery pack tends to have a higher operating temperature when the batteries are under loading, for example when being charged or discharged, than the outside of the battery pack. That is, in the arrangement shown where the anodes are at the centre of the battery pack, and the cathodes are on the outside of the battery pack, the anodes operate at a higher temperature than the cathodes.

[0080] However in the general case, the layout shown in Figures 3 to 6 need not necessarily have the anodes facing the central aisle 313 and the cathodes on first and second outer sides of the battery pack, but the arrangement of battery cells may be reversed such that the anodes are presented on the outside of the battery pack, and the cathodes lie either side of the central aisle 313 in the middle of the battery pack.

[0081] The central region of the battery pack between the first and second stacks 311 , 312 may require more thermal management in the form of assisted heating or cooling than the outer sides 314, 315 of the battery pack.

[0082] Although in Figures 3 to 6 there is shown a battery pack having two stacks of individual battery cells, a battery pack may comprise a single stack of battery cells. Further, although the battery pack shown comprises five layers of battery cells, in the general case battery pack can comprise one or a plurality of layers of battery cells.

[0083] There will now be described specific embodiment heat exchangers according to the present invention.

[0084] Referring to Figure 7 herein there is illustrated schematically a first heat exchanger device 700 according to a first specific embodiment of the present invention. The heat exchanger 700 comprises a central core section 701 ; a first end housing or casing 702 at a first end of the central core section; and a second end housing or end casing 703 at a second end of the central core section. The central core section 701 extends between the first end housing 702 and the second end housing 703. The first end housing has a fluid inlet tube 704 for introducing heat exchange fluid into the heat exchanger and a fluid outlet tube 705 for discharging heat exchange fluid from the heat exchanger. The main axial length direction is of the fluid inlet tube and fluid outlet tube are each in a direction substantially parallel to the main length axis of the heat exchanger core 701 in the embodiment shown. The fluid inlet tube 704 is disposed on a first side of the heat exchanger and the fluid outlet tube 705 is disposed on a second side of the heat exchanger, so that the fluid inlet tube and the fluid outlet tube are located on opposite sides of a central plane which bisects each of the internal channels of the heat exchanger core. On other embodiments they may both be on a central plane.

[0085] Referring to Figure 8 herein, there is illustrated schematically in perspective view the first embodiment heat exchanger 700 placed in situ in a battery pack, where the central core section 701 is located in a central aisle between first and second stacks of battery layers comprising said battery pack. In use, individual battery cells are arranged in layers, each layer comprising a row of individual battery cells, wherein a first plurality of layers are stacked in a first stack on one side of the heat exchanger core and a second plurality of layers are stacked in a second stack on the other, opposite side of the heat exchanger core. At the first ends of the stacks, the first end housing 702 protrudes beyond the stacks, and at the second ends of the stacks, the second end housing 703 protrudes beyond the second ends of the stacks so that the central core section 701 of the heat exchanger extends at least the full length of each individual layer of battery cells.

[0086] The individual battery cells are arranged such that their main length axis are arranged so as to intersect a plane which is parallel to a main central plane in of the heat exchanger core, and in a best mode the individual battery cells are arranged so that their main central length axis is arranged perpendicular to the plane which is parallel to the main central plane of the heat exchanger core.

[0087] In the general case, the individual battery cells are not necessarily cylindrical in external shape, but may be square or rectangular in cross sectional area as viewed in a direction perpendicular to a main central axis of the battery cell.

[0088] Referring to Figures 9 to 12 herein, there is illustrated schematically a third specific embodiment of a battery pack being a subset of the general layout as shown in Figures 3 to 6 herein, and in which individual layers of batteries are stacked in a log-pile arrangement, each individual stack comprising a plurality of layers of individual battery cells, wherein two stacks of layers are spaced apart from each other with a central passageway or aisle located there between.

[0089] Referring to Figure 9 herein, the third embodiment battery pack comprises a plurality of individual self-contained battery cells. Each said battery cell comprises a substantially circular cylindrical body, having an anode at a first end, and a cathode at a second end of the battery cell body. Preferably the battery cells comprise lithium ion batteries.

[0090] Referring to Figure 10 herein, there is shown the battery pack of Figure 9 in view from one side, showing the arrangement where the main central axes of the individual battery cells are arranged in a hexagonal pattern, having a central battery cell and 6 battery cells arranged in a hexagon around a main central battery cell. Equivalently, a main central length axis of each individual battery cell is at the apex of an equilateral triangle formed with the main central axes of two other immediately adjacent battery cells. In this arrangement, adjacent individual layers of battery cells interleave with each other so that the circular cylindrical bodies of the batteries pack closely together with each other in a optimally compact arrangement. [0091] Referring to Figure 1 1 herein, there is illustrated the battery pack of Figure 9 herein in view from above. In plan view, a main central axis of each substantially circular cylindrical battery cell of the upper row aligns with a position one radius distance away from the main central length axis of a battery cell in an adjacent underlying row, so that the main central axes of the battery cells of the upper row are offset with the main central axes battery cells of the row of cells underneath by one battery cell radius.

[0092] Referring to Figure 12 herein, there is illustrated the battery pack of Figure 9 herein in view from one end, showing the first stack parallel to and spaced apart from the second stack, each stack comprising 5 rows of individual battery cells, there being a passageway or gap between the first and second stacks. In the specific arrangement shown, a plurality of anodes of the first stack are aligned substantially on a first plane, and a plurality of anodes of the second stack are aligned substantially on a second plane, wherein the first and second planes of anodes are spaced apart from each other and are substantially parallel to each other.

[0093] Along each horizontal layer as shown in Figure 9 to 12 herein, electrical connection to each battery cell in a row is made via a respective said anode contact of said battery cell via at least one common anode bus extending across a number of cells; and electrical connection to the cathode of each battery cell in a row is made via a respective common cathode bus which connects together the cathodes of the battery cells. The anode bus connects together the anodes of a plurality of battery cells, and a cathode bus connects together the cathodes of a plurality of battery cells. In some battery cell types, the anode contact of each battery cell may have a smaller surface area than the cathode contact of the battery cell.

[0094] Each bank or stack of batteries has individual batteries arranged with their anodes all presenting along a first plane, and their cathodes all presenting along a second plane, wherein said second plane is parallel to and spaced apart from said first plane.

[0095] In each stack, the individual substantially circular cylindrical battery cells are arranged in parallel to each other in a log-pile arrangement in which the main central axis of each individual battery cell lies at the centre of a hexagonal cell pattern when viewed in a direction parallel to the main length axes of the plurality of battery cells.

[0096] When arranged in an electric vehicle or a stationary application, there are a plurality of battery packs, each battery pack comprising a plurality of battery cells. For example in one configuration there may be 36 battery packs, each having 12 layers of individual cells, making 432 individual layers, each layer containing a plurality of individual battery cells.

[0097] In the arrangement shown in Figures 9 to 12 a battery pack comprises 2 stacks of battery cells, each stack comprising 5 layers, each layer comprising 21 individual battery cells, containing 210 individual battery cells in a battery pack.

[0098] In yet another arrangement, a battery pack may comprise 2 stacks each stack comprising 5 layers, each layer comprising 55 individual battery cells, giving a total of 550 battery cells per battery pack.

[0099] In the general case, the number of individual battery cells in each battery pack is determined by available space, weight and temperature control considerations, and the number of battery packs in a vehicle is determined by the available space, weight, cost, design range and overall design charge capacity of the particular electric vehicle.

[0100] In use, under conditions of heavy load, that is, where the battery is being charged or discharged at a high rate, the battery generates heat and therefore needs to be cooled to keep the battery cells within their optimum operating temperature range. Further, when a vehicle or stationary application or stationary battery installation has been standing unused in cold weather the entire battery pack may be at a temperature below its optimum operating temperature range and therefore the temperature of the battery pack may need to be regulated to maintain a temperature within its optimum operating temperature range.

[0101] Referring to Figure 13 herein, there is illustrated schematically in perspective view the first embodiment heat exchanger 700 placed in situ in a battery pack, where the central core section is located in a central aisle between first and second stacks of battery layers comprising said battery pack. In an arrangement where the anodes of the individual battery cells in adjacent stacks face opposite each other across a central aisle or passageway as shown in Figure 13, there is a need for temperature control along the central aisle or passageway.

[0102] In a variation of the battery pack of Figure 13 herein, comprising only a single stack of battery cells, the heat exchanger would be placed across the ends of the individual battery cells, there being a corresponding respective thermal path between the end surface of each individual battery cell and an outer surface of the heat exchanger, so that heat can be transferred from the end surface of each individual battery cell, through an electrical bus which connects the ends of a plurality of battery cells in a row, through a layer of electrically insulating material, and to the outer surface of the core of the heat exchanger. There may be a layer of electrically insulating high thermal conductivity paste between one side of the layer of electrically insulating material and the surface of the heat exchanger core, and there may be a layer of high thermally conductive electrically insulating paste between the electrical bus and the other side of the layer of electrically insulating material to make an efficient thermal path between the end of the battery cell and the outer surface of the heat exchanger core section. .

[0103] Referring to Figure 14 herein, there is illustrated schematically the first heat exchanger in view from one side. The first end housing 702 is connected to a first end of the heat exchanger core 701 , and the second end housing 703 is connected to the second end of the heat exchanger core.

[0104] The central core section 701 comprises a first end 1400 to which said first end housing 702 is fitted; a second end 1401 to which said second end housing 703 is fitted; a first side 1402 extending between said first and second ends; a second side 1403 extending between said first and second ends; an upper connecting side 1404 extending between said first and second ends; and a lower connecting side 1405 extending between said first and second ends. The upper connecting side connects a first edge of said first side with a first edge of said second side; and said lower connecting side connects a second edge of said first side with a second said second side. Located internally of the heat exchanger core, between the first and second sides there are a plurality of individual channels each of which extends along the main length of the heat exchanger core.

[0105] Within the heat exchanger core there are a plurality of parallel channels each channel extending the whole length of the heat exchanger core, and arranged as a single layer of channels within the core, so that as viewed in Figure 14, the individual channels are arranged top to bottom such that when the heat exchanger core is positioned in a central passageway between first and second stacks of battery cells, a projection of the circular cylindrical outer end surface of each battery cell projects through at least one said first channels carrying heat exchange fluid in a first direction, and through at least one said second heat exchange fluid channels carrying heat exchange fluid in a second direction, opposite to said first direction. This means that an externally facing surface area of the heat exchanger core which faces immediately opposite an anode of a particular battery cell has behind it internally in the core, both a portion of a first channel and a portion of a second channel with heat exchange fluid flowing in contra direction. Each anode is in thermal contact with, but electrically isolated from the outer facing surface of the heat exchange core 701 , and heat is transmitted between the area footprint of the anode of an individual battery cell and the corresponding footprint area on the surface of the heat exchanger immediately opposite that anode. When the anode is being cooled, heat is transferred from the anode to the outer surface of the heat exchange core, and when the battery is being warmed by the heat exchanger, heat is transmitted from the corresponding footprint area on the outer surface of the exchange to the anode.

[0106] In each case, whether the anode is being heated or cooled, heat is transferred between at least one channel of heat exchange fluid flowing in the first direction, and at least one channel of heat exchange fluid flowing in the second, opposite direction via the sidewall of the heat exchanger core.

[0107] Conversely, as it would be understood by the person skilled in the art, if the battery pack is arranged such that the anodes point outwardly towards the outer sides of the battery pack and the cathodes facing inwardly either side of the central passageway, then there would be heat transfer between the cathodes at the end surface of each battery cell, and the heat exchanger core and therefore each individual cathode would have an area footprint, the perimeter of which projects through at least one first heat exchange fluid channel and at least one second heat exchange fluid channel as projected in a direction across or perpendicular to the flow direction of each or either of said first or second heat exchange fluid channels.

[0108] Referring to Figure 15 herein, there is shown the first heat exchanger in view from above. The first heat exchanger is symmetric when rotated about a main central length axis by 180°, and so a view of the first heat exchanger from underneath corresponds to the view of the first heat exchanger from above. Rotating the heat exchanger about a main central length axis will exchange the positions of the first fluid connection tube with the second fluid connection tube and vice versa. Either fluid connection tube may be used either as a fluid inlet or a fluid outlet for connecting the heat exchanger externally to a pipework of an electric vehicle’s thermal management system, which may include a pump for pumping heat exchange fluid, and the one or more further air / liquid radiators or air / liquid heat exchangers for exchanging heat extracted from the first heat exchanger with atmospheric air.

[0109] As shown in Figures 14 and 15 herein, the first end housing has an inlet pipe 704 and an outlet pipe 705, where the inlet pipe lies on an opposite side of the first end housing to the outlet pipe, and vice versa, and the inlet pipe lies on an opposite side of a main central plane which bisects the heat exchanger core and which extends along a length direction of the plurality of channels within the core.

[0110] As shown in Figure 15 herein, when viewed from above the core of the heat exchanger is relatively long with respect to the width or thickness of the heat exchanger core, in the example shown the width of the heat exchanger core has a ratio of between 0.3% and 0.6% of the overall length dimensional of the heat exchanger core and the height of the heat exchanger core has a ratio of between 6% and 8% of the length of the heat exchanger core.

[0111] At the second end of the heat exchanger core, in the first embodiment heat exchanger, the second manifold 703 has no inlet or outlet pipe, but rather serves to return heat exchange fluid which has been introduced at the first end, and which has travelled to the second end of the heat exchanger, sending the fluid back from the second to the first end at which it out lets from the heat exchanger via the fluid outlet pipe.

[0112] Referring to Figures 16 and 17 herein, there is illustrated schematically in perspective view from above and one end, the central heat exchange core of the first heat exchanger with the second end housing present, but the first end housing removed. Since the heat exchange core is formed as an extrusion, the cross-section through the core taken in a direction perpendicular to a main length axis of the core is the same at all distances along the length of the core. This may have a manufacturing advantage that heat exchangers of different lengths but otherwise equivalent structure may be created using the same components, but with different lengths of extruded heat exchanger core.

[0113] The heat exchanger core comprises a first sidewall plate 1600; a second side wall plate 1601 , said second side wall plate being spaced apart from and lying parallel to said first side wall plate; and upper closure plate 1602, the upper closure plate extending between and connecting an upper perimeter of the first side wall plate and an upper perimeter of the second side wall plate 1601 ; a lower closure sidewall plate 1603, the lower closure plate extending between a lower perimeter of the first sidewall plate 1600 and a lower perimeter of the second side wall plate 1601 and connecting said respective lower sidewall perimeters; extending between the first and second sidewalls, are provided a plurality of internal divider walls 1604-1612 which in the embodiment shown connect the first and second side wall plates and divide the interior cavity bounded by first side wall plate 1600, second side wall plate 1601 and one, upper closure plate 1602 and lower closure plate 1603 into a plurality of channels or passages, in this case 10 individual channels/passages through which heat exchange fluid may flow. The upper and lower end walls and the internal divider walls are positioned between and extend between the first and second side walls.

[0114] Between the first and second side walls 1600, 1601 there are defined across the width of the core a plurality of channels comprising first and second outermost channels 1613, 1622 respectively and a plurality of inner channels 1614 - 1621.

[0115] Each individual channel is respectively bounded on a first side by a portion of said first side wall 1600; on an second, opposite side by a portion of second side wall 1601 ; on a third side extending between said first and second sides, by either a first dividing wall or in the case of the outermost channels (upper and lower most as shown in Figure 16) by the upper closure wall 1602 or the lower closure wall 1603; and on the fourth side by said second divider a wall 1601 , so that in cross- sectional area in a direction perpendicular to the main length direction of each channel, each channel has a substantially rectangular shape.

[0116] Each internal divider wall 1604-1612 separates two adjacent channels and connects between the first and second sidewalls. Since the heat exchange fluid flows in alternate channels in opposite directions, this means that for the inner channels, heat exchange fluid flowing in that channel is thermally connected through each of the adjacent respective dividing walls bounding that channel with a pair of adjacent channels, one each side of said channel and in each of said adjacent channels the heat exchange fluid is flowing in an opposite direction to the direction of flow of heat exchange fluid in said channel.

[0117] The two outermost channels 1613, 1622 are bounded only on one side by adjacent channel, the other side of the outer most channels being bounded by atmospheric air on the other side of the respective upper closure plate 1602 and lower closure plate 1603.

[0118] As shown in Figures 17, 18 are a plurality of circles on an outer surface of first side wall 1600. These circles represent areas of the outer surface of the first sidewall which lie opposite the anode of an adjacent individual battery cell when the heat exchanger is placed in a battery pack between two stacks of battery cells. The circular areas represent areas where there is shortest thermal path between the outer surface of the first sidewall 1600 each circular area, a corresponding respective anode area of a respective battery cell. [0119] In the battery pack, the outer surface of the first sidewall 1600 is in thermal contact with the anodes of a plurality of battery cells, but may be electrically isolated from the anodes of the battery cells by an electrical insulating layer and, for each row of anodes, by a respective anode bus which connects the anodes of the battery cells.

[0120] Each area of the outer surface of the first sidewall 1600 which has the preferred strongest and most direct thermal path to a corresponding anode lies on an area of the first sidewall 1600 which straddles at least two channels present on the opposite and inner face of the first sidewall. Further, each area of the outer surface of the first sidewall 1600 which has the most direct thermal path to a corresponding respective end surface of a battery cell, also lies over at least one dividing wall 1604- 1612. Consequently each preferentially thermally conducting area on the surface of the first sidewall 1600 is in thermal connection through the thickness of the first sidewall 1600 with an internal first channel carrying fluid flow in a first direction and an internal second channel carrying fluid flow in a second direction, and with at least one said dividing wall. The areas of the surface of the first sidewall which have preferential heat transfer with the opposing anodes of the battery cells in the first stack are those areas which are physically closest to the anodes. Those areas are delineated approximately by projecting a perimeter area around the anode of a battery cell in a direction perpendicular to the main plane which coincides with the outer surface of the first sidewall.

[0121] Referring to Figure 17 herein, there is illustrated schematically in perspective view from above and one side the central heat exchanger core section and the second end housing 703 of the first heat exchanger.

[0122] Referring to Figure 17 herein, there is illustrated schematically the outer surface of the first sidewall 1600. In practice, the outer surface of the sidewall may be uniform and substantially planar, and it is only when the heat exchanger is introduced into a battery pack and that the sidewall of the heat exchanger core faces an array of anodes and is in close thermal contact with the anodes that the areas of preferential thermal conductivity are formed, since the placement of those areas on the external surface of the first sidewall 1600 depend upon the relative placement of the individual layers of batteries with respect to the placement of the individual heat exchange fluid channels inside the heat exchanger core.

[0123] Referring to Figure 18 herein, there is illustrated schematically in perspective view, the heat exchanger core of the first heat exchanger having superimposed on the outer surface of the first sidewall a plurality of circles, each circle representing a surface area of preferential heat transfer for transfer of heat between an anode of an adjacent battery cell and the sidewall 1600 of the heat exchanger core.

[0124] On the other side of the heat exchange core, the second side wall 1601 has a similar pattern of areas of preferential heat transfer, where the thermal path between the respective preferential area and an anode of a second stack of battery cells is shortest.

[0125] An outwardly facing surface of the first side wall 1600 is partitioned into a plurality of first partition areas, each of which coincides with the area of one end of a corresponding respective individual energy cell. Projecting the perimeters of the first partition areas directly through the thickness of the first sidewall in a direction transverse to the main plane of the outer surface of the first sidewall, are a plurality of second partition areas on the inside of the heat exchange core and on the inner surface of the first sidewall 1600. Each of those second partition areas comprises an inner surface of at least one first said channel and an inner surface of at least one second said channel, such that each second partition area experiences heat transfer with heat exchange fluid flowing both in the first direction and in the second direction, and each said second partition area comprises a portion of inner wall area of a first channel and a portion of inner wall area of a second channel, said portions of first channel in a wall area and second channel in the wall area being divided from each other by a dividing wall. For example, if the heat exchange core is arranged opposite a stack of battery cells, where each battery cell has a circular anode or cathode plate, the main plane which lies substantially parallel to the main plane of the sidewall of the heat exchanger core, the partition area is the area of the outer face of the sidewall which is facing opposite the circular area of the circular anode or cathode plate. If the anode or cathode plate had a rectangular or square area, then the partition area on the outer surface of the sidewall would be a corresponding rectangular or square area. In the general case, the shape of the partition area matches the shape of the anode or cathode immediately opposite the outer wall of the sidewall.

[0126] In the first heat exchange core, each of the channels have equal cross- sectional area to each other as viewed in a direction along a main length axis of each channel so that nominally for an equal fluid pressure in each channel, the flow rate within each channel will be the same as for any other said channel.

[0127] Also shown in Figure 18 are arrows indicating a flow direction. The flow direction is determined by the configuration of the inlet/outlet manifolds, which distribute fluid flow in a first (flow) direction amongst alternate odd numbered channels counting from a first outer most channel, and collects fluid flow in a second (return) direction from even numbered channels counted from the first outer most channel.

[0128] Referring to Figure 19 herein, there is shown schematically the heat exchanger core in view from a first end. As the core is symmetric, a view from the second end corresponds to the view from the first end. The plurality of individual channels 1613 - 1622 are arranged in a line, in which each inner fluid channel arrange from top to bottom is bounded on one side by said first side wall; on another side by said second side wall; and above and below by a corresponding adjacent channel. The uppermost fluid channel 1613 is bounded on one side by a portion of the first sidewall; on another side by a portion of the second side wall, above by the upper plate 1602; below by a dividing wall and on the opposite side of the dividing wall by an inner fluid channel. The lower outer most channel 1622 is bounded on one side by a portion of the first sidewall, on another side by a portion of second side wall, above by a dividing wall, and on the other side of the dividing wall by an adjacent inner channel, and underneath by the lower end plate 1603.

[0129] Referring to Figure 20 herein, there is illustrated schematically in view from one end the first heat exchanger core and the second end housing, with the first end housing removed. The second end housing comprises an aperture which encloses an outer perimeter surface of one end of the first heat exchanger core. Spaced apart from the end of the heat exchanger core and contained within the end housing, there is a cavity into which fluid flows in and out of via the open ends of the plurality of channels, which open out into the cavity. Fluid flows into the cavity via said first plurality of channels, mixes within the cavity and flows out of the cavity via said second plurality of channels.

[0130] Referring to Figure 21 herein, there is illustrated schematically in cut away view from one side, bisected down a plane perpendicular to the first and/or second sidewalls and which bisects each channel within the central heat exchanger core. In the first heat exchanger core there are 10 parallel channels, each extending between said first end and said second end of said heat exchanger core, as described herein before. A plurality of inner channels lie between first and second outermost channels 1613, 1622. Since the heat exchanger core is symmetric, the direction of fluid flow within the channels is determined solely by the configuration of the first end housing at one end of the central heat exchanger core. In the first heat exchanger embodiment, each individual fluid channel has identical dimensions to each other individual fluid channel and has a same cross-sectional area as viewed in a direction perpendicular to the main length axis of the heat exchanger core.

[0131] Referring to Figure 22 herein, there is illustrated schematically in perspective view a first end housing 702 of the first heat exchanger which is attached to a first end of the first heat exchanger core. The first end housing 702 comprises a first outer shell component 2200; a second outer shell component 2201 and an internal dividing wall 2203 located between the first and second outer shells. The first and second outer shells each comprise a fluid pipe 704, 705 respectively. Since the first and second outer shells are identical to each other they may be formed from the same moulding or casting. In one embodiment, the outer shells and internal divider plate 2203 are made of a plastics material and the first end housing may be fitted to the end of the second heat exchange core by means of a suitable adhesive, for example epoxy adhesive. In other variations, the first and second outer shells and/or the dividing plate 2203 may be cast from a metal material and attached to the end of the second heat exchange core either by an adhesive, or by soldering or brazing or by a seal and retaining clip.

[0132] Each outer shell comprises a fluid connecting pipe or tube 704, 705 for connecting the end housing to an external heat exchange fluid system. In the embodiment shown, the fluid pipes are arranged so as to connect with a fluid inlet and fluid outlet tube of a battery system thermal management system such that the central axes of the fluid connection pipes lie parallel to the main length of the heat exchanger, but the centres of the fluid pipes are offset either side of a main central plane which bisects the heat exchanger parallel to the first and second sidewalls.

[0133] Referring to Figures 22 to 26 herein, said first end housing comprises a first outer shell component 2201 ; a second outer shell component 2202; a partition member 2203 located between said first outer shell and said second outer shell; said partition member dividing a space between said first outer shell and said second outer shell into a first cavity and a second cavity; said partition member 2203 comprising a first plurality of castellated manifold wall formations 2204 - 2208 arranged to seal across a plurality of said dividing walls extending between said first sidewall and said second sidewall of said heat exchanger core, said first plurality of wall formations for directing fluid between said first cavity and said first plurality of channels; and said partition member comprising a second plurality of castellated wall formations for directing fluid between said second plurality of channels and said second cavity.

[0134] Depending upon whether the first connection tube 704 is connected to a flow pipe or a return pipe of the external heat exchange system, the first connection tube 704 becomes either a fluid inlet or a fluid outlet respectively. Similarly, depending upon whether the second connection tube 705 is connected to a flow pipe or a return pipe of the external heat exchange system, that’s tube becomes either a fluid inlet or a fluid outlet tube or pipe.

[0135] Similarly, if the first connection tube 704 is connected to a flow pipe external heat exchange system which supplies heat exchange fluid under pressure, then the first cavity between the first inlet tube 704 and the partition walls becomes an inlet manifold, and the second cavity between the partition walls and the second fluid connection tube 705 becomes outlet manifold. Reversing the overall direction of flow by reversing the connections of fluid pipe 704, 705 to the external heat exchange system would convert the second cavity into an inlet manifold and the first cavity into an outlet manifold.

[0136] An inner surface of the first outer shell component and an inner surface of the second outer shell component, together form an inner surface which has dimensions which slides over and fits closely around the outer surfaces of the first and second sidewalls and upper and lower walls of the end of the heat exchanger core so that the first end housing can be slid over an end of the first heat exchanger core and attached thereto. When attached to the heat exchanger core, the plurality of wall formations 2204 - 2214 of the partition member 2203 abut an end face of the first heat exchanger in a fluid tight manner, thereby dividing the channels of the first heat exchanger into a first set of channels which are in communication with the first cavity, and a second set of channels which are in communication with the second cavity.

[0137] The partition member 2203 comprises a substantially flat plate member 2215 which divides between first and second cavities within the end housing; at an open end of the end housing, the wall formations of the partition member are arranged into a plurality of wall portions which lie parallel to the main partition member but which are spaced apart from the flat plate member 2215 to one side of the plate member; a second plurality of wall portions which lie parallel to the plate 2215 and are spaced apart from the flat plate member on a second, opposite side of the plate member; and a plurality of transverse wall portions, each of which lie across and perpendicular to a main plane of the partition member, and perpendicular to a main plane of the first plurality of wall portions 2204 - 2208 and perpendicular to a main plane of the second plurality of wall portions 2209 - 2213.

[0138] The plurality of internal divider walls are recessed relative to the open mouth of the end housing so that one end of the heat exchange core can slide into the open mouth of the first end housing and locates between the outer shell walls of the end housing such that the end of the heat exchange core meets the plurality of wall formations within the end housing, the configuration of the dividing walls inside the end housing determining which channels are designated first channels having a first flow direction, and which channels are designated as second channels having a second flow direction. The end of the heat exchange core slides into the open mouth of the end housing so that a portion of the outer surface of the first sidewall, a portion of the outer surface of the second side wall, an outer surface of portions of the upper and lower connecting walls, contact the inside surfaces of the outer shells of the end housing, and such that the ends of the first and second sidewalls and the ends of the connecting walls lie immediately opposite ends of the end housing wall formations, the ends of the end housing wall formations being recessed / inset in the end housing in the length direction relative to the end of the open mouth formed by the outer shell walls of the end housing.

[0139] Referring to Figure 23 herein, there is illustrated schematically in exploded view the first end housing showing in more detail the central partition plate 2203 which divides an internal cavity between the first and second outer shells into first and second fluid chambers.

[0140] Referring to Figure 24 herein, there is illustrated schematically in exploded view the first end housing showing the inlet chamber or cavity and outlet chamber or cavity and the central partition plate 2203 and the plurality of wall formations which direct fluid from the inlet fluid chamber to the outlet fluid chamber.

[0141] Referring to Figure 25 herein, there is illustrated schematically the first end housing in end view, showing the first and second outer shells and the central partition plate 2203, showing a plurality of apertures defined by the plurality of wall portions of the partition plate which separate the fluid flow into a first set of fluid flows in a first outward or flow direction, and a second set of fluid flows in a second, or return direction, in which a first set of apertures connect with said inlet fluid chamber or cavity, and a second set of apertures connect with said fluid outlet chamber or cavity. [0142] Referring to Figure 26, there is shown the first end housing in view from one side. The other side of the first end housing corresponds.

[0143] Referring to Figure 27 herein, there is illustrated schematically a second end housing 2700 of the first heat exchanger. The second end housing is designed as a return manifold, wherein coolant which is introduced to a first end of the heat exchange core travels along a first set of channels and exits each channel of said first set of channels at a second end of the heat exchange core, enters a chamber or cavity in the second end housing 2700, and is forced under pressure into the second ends of a plurality of second channels, being return flow channels.

[0144] The second end housing comprises a first end housing side wall 2701 ; a second end housing side wall 2702 spaced opposite, parallel to and spaced apart from said first end housing side wall 2701 ; an upper wall 2703 extending between and upper end of said first side wall 2701 and said second side wall 2502; a lower wall 2704, said second wall extending between a lower end of said first side wall 2701 and a lower end of said second side wall 2702; and an end wall (not shown in Figure 27) which connects with said first side wall 2701 , said second side wall 2702, said upper wall 2703 and said lower wall 2704 arranged to close off a cavity or chamber formed between said walls, such that said second manifold is open at one end and closed off at another opposite end at which said end wall resides.

[0145] An aperture described by the internal surfaces of the first side wall 2701 , second side wall 2702, upper wall 2703 and lower wall 2704 is of dimensions such as to closely match the outer dimensions of the perimeter around the outside of the heat exchange core, such that the second end housing closely fits over the end of the second heat exchange core and can be retained to the second end of the second heat exchange core either by means of an epoxy resin adhesive or by means of a seal and clip. In the best mode, the heat exchanger core is an extrusion of indeterminate length and has a same cross-sectional profile along its length, so that the heat exchanger core can be cut at any suitable length and will have the same outer perimeter dimensions all the way along its length, and the first and second sidewalls, upper plate and lower plate each have a smooth substantially planar outer surface which enables the first and/or second end housings to be slid over the outside of the first heat exchanger core, and attached thereto. In a second aspect the extrusion may be machined at one or both ends to suit the fitment of the end piece.

[0146] In an alternative attachment method, where the material of the second end housing is the made of a material which can be soldered or brazed to the material of the first heat exchanger core, the second end housing may be connected to the second end of the first heat exchanger core by brazing or soldering the outer face of the second end housing to an outer surface of the end of the first heat exchange core.

[0147] In the embodiment shown, the second manifold does not have any internal baffle plates to direct the flow of coolant fluid, but comprises a single open unobstructed cavity or chamber in which separate streams of coolant fluid issuing out of the second ends of the plurality of flow channels can mix together in turbulent flow, before entering the second ends of the plurality of return flow fluid channels for a return passage to the first end of the heat exchanger.

[0148] Referring to Figures 28 to 38 herein, there is illustrated schematically a second embodiment heat exchanger.

[0149] Referring to Figure 28 herein, there is illustrated schematically in perspective view from one side a second heat exchanger 2800 according to a second specific embodiment of the present invention. The second heat exchanger comprises a central heat exchanger core section 2801 ; a first end housing 2802 at a first end of the central core section; and a second end housing 2803 at a second end of the central core section. The second end housing 2803 is substantially as described herein before with respect to the first embodiment.

[0150] Referring to Figure 29, there is illustrated schematically the second heat exchanger in view from above.

[0151] Referring to Figure 30 herein, there is illustrated schematically in perspective view from one end the core component 2801 of the second heat exchanger. The core component 2801 has first and second ends, a length between the first and second ends; a thickness in a direction perpendicular to the length; and a width in a direction perpendicular to the thickness and perpendicular to the length.

[0152] The heat exchanger core comprises a first side wall 3000; a second side wall 3001 ; an upper wall 3002 and a lower wall 3003. First and second sidewalls 3000, 3001 each comprise a sheet of plate material, the first and second sidewalls being parallel to each other and spaced apart from each other to define a plurality of fluid - containing channels there-between; said upper wall 3002 extends between an upper perimeter of said first side wall and an upper perimeter of said second side wall, connecting said first and second sidewalls at a first side of the core; said lower wall 3003 extends between a lower perimeter of said first side wall 3000 and a lower perimeter of said second side wall 3001 , connecting said sidewalls at a second side of said core. Extending across a distance between said first and second sidewalls, and between an inner surface of the first sidewall 3000 and an inner surface of the second sidewall 3001 there are a plurality of internal divider walls 3004-3013 each of which extend fully along the length of the heat exchanger core between first and second ends of the heat exchanger core, dividing the heat exchanger core into a plurality of channels, 3014 - 3024 each channel extending along a full length of the heat exchanger core. The divider walls, upper and lower end walls each extend between the first and second sidewalls and form connecting walls which connect the first sidewall to the second sidewall.

[0153] As shown in Figure 30, the width of the heat exchanger core is between the upper and lower walls 3002, 3003 and the thickness of the heat exchanger core is between the outer facing surface of the first sidewall 3000 and the outer facing surface of the second sidewall 3001.

[0154] Each individual channel has an inner surface comprising a portion of an inner surface of the first sidewall; a portion of an inner surface of said second side wall; an upper internal surface and a lower internal surface, where the upper and lower internal surfaces are formed either by a said dividing wall, or by a said upper outermost or lower outermost wall. The heat exchanger core has a length between its first and second ends, a width between the upper wall 3002 and the lower wall 3003, and a depth between the outer surfaces of the first and second sidewalls. The plurality of channels 3014-3024 are arranged across a width in a single row in which the plurality of channels lie side-by-side, and across a depth of the heat exchanger core, there being the thickness of the first sidewall, the thickness of the second side wall, and the thickness of a single channel.

[0155] Each individual dividing wall 3004-3013, and the ends of the upper walls 3002 and the end of the lower wall 3003 form a flat surface lying on an end plane which lies perpendicular to a first outer side wall plane coinciding with the outer surface of the first sidewall, and perpendicular to a second outer side wall plate line perpendicular to an outer surface of the second side wall. The surface comprising the end of the first sidewall, the ends of the dividing walls, the end of the second side wall and the ends of the upper and lower walls abuts a corresponding surface on the first end housing and forms a fluid-tight connection with the first manifold, so that the first manifold divides the flow of heat exchange fluid in the first direction and second direction and determines the division of the plurality of channels into a first set of channels having flow in a first direction and a second set of channels having flow in a second and opposite direction.

[0156] In the second heat exchanger core, there are four different channel types, each being substantially rectangular in cross sectional area in a direction transverse to the main the heat exchanger core, and each of the four channel types having a different cross-sectional area. Each channel type has a same depth, with the variation in cross-sectional areas being determined by the four different widths of the four different channel types. By using a plurality of different cross-sectional areas for a plurality of different channel types, and by dividing the channels into a first set of channels and a second set of channels in which fluid flows in a first direction first channels and a second direction second channels, the exchange of heat between fluid flowing in the first and second channels can be optimised so as to obtain as near as possible a uniform external surface temperature on the outside of each of the first and second sidewalls 3001 , 3002. [0157] In the embodiment shown, across the width of the heat exchanger core there are eleven separate channels, arranged side-by-side and parallel to each other. First and second outermost channels 3014, 3024 each have a cross-sectional area in a direction perpendicular to a main length of said channel which is smaller than a cross-sectional area of each of the other inner channels 3015 - 3023 in a direction perpendicular to the main length of each said channel, so that the fluid flow capacity of each of the outermost channels is relatively lower than the fluid flow capacity of any one of the innermost channels 3015-3023. Additionally, of the innermost channels there are three different channel sizes, channels having different cross- sectional area in the direction transverse to fluid flow. A first channel type 3016 has a first cross-sectional area, wherein the first channel type (3016, 3018, 3020, 3022) has a ratio of width to depth of the order of w/d = 3.3 - 3.5 and preferably 3.4; a second channel type (3015, 3023) has a ratio of width to depth of the order w/d=2.9 to 3.1 and preferably 3.0; and a third channel type 3017, 3019, 3021) has a ratio of width to depth of the order w/d= 2.2 to 2.4 and preferably 2.3, so that the relative ratios of channel area in the direction perpendicular to fluid flow for the 4 channel types are:

Inner channels type 1 - nominal area 1.0;

Inner channels type 2 (3015 - area 80% - 86% of the type 1 channel area Inner channels type 3 - area 57% - 63% of the type 1 channel area

Outer channels - area 38% - 44% of the type 1 channel area

[0158] In the general case the cross-sectional area of each individual channel perpendicular to its main length axis may be designed to optimise for individual types of battery array, so as to even out the surface temperature of the outside faces of the outer sidewalls to achieve the smallest temperature gradient across the outer surfaces of the sidewalls both in the length direction, and in the width direction. In the general case, each individual channel may have a surface area and flowrate capacity which is different to each other individual channel, or one or more individual channels may be designed to have the same cross-sectional area as one or more other individual channels. The width of each individual channel across the heat exchanger core may be varied as a design parameter to optimise for any particular type of battery pack.

[0159] As shown in Figure 30 herein, first and second flow directions are illustrated schematically by first and second arrow directions. Since the heat exchanger core is an extruded component, the flow direction in each of the channels is determined by the design of the inlet and outlet manifolds.

[0160] When used with a plurality of circular cylindrical energy cells, each having their main length axis arranged perpendicular to the plane of the outer surface of the first sidewall 3000, and end surface of each energy cell lies adjacent to a corresponding portion of the outer surface of the first sidewall 3000. Shown in Figure 30 are a plurality of projected circular areas being areas of the outer surface of the first sidewall 3000 which are physically closest to an adjacent end wall of an energy cell, and also being the areas which are in maximum thermal contact with the end walls of the array of energy cells. Each of these projected circular areas on the outer surface of the first sidewall 3000 aligns with at least one first channel and at least one second channel so that heat may be exchanged between the end surface of the energy cell and fluid flowing in a first channel and fluid flowing in a second channel through the thickness of the first sidewall 3000 and through an underlying internal dividing wall.

[0161] Referring to Figure 31 herein, there is illustrated schematically the heat exchanger core of the second heat exchanger, showing the end surface comprising the ends of the first sidewall 3000, the second sidewall 3001 ; the upper wall 3002, the lower wall 3003, and the plurality of dividing walls 3004-3013.

[0162] Referring to Figure 32 herein, there is illustrated in view from the first end, looking towards the second end, the heat exchanger core and the second end housing of the second heat exchanger. The second end housing has an internal aperture having an inner surface which is parallel to the outer surface of the first sidewall 3000, second side wall 3001 , upper wall 3002 and lower wall 3003, such that the end manifold slides over the second end of the heat exchanger core to make a good fit. Depending upon the materials of the second end housing, and the materials of the heat exchanger core, the second end housing can either be brazed, or soldered to the outer surface of the heat exchanger core, or the second end housing may be attached to the outer surface of the second heat exchange core using an epoxy adhesive. Alternatively a seal and a clip may be used.

[0163] Referring to Figure 33 herein, there is illustrated schematically in cutaway view from one side a portion of the heat exchanger core and the second end housing of the second heat exchanger disclosed herein, showing internally a plurality of channels within the heat exchanger core. In the second heat exchanger, at the second end of the plurality of channels are all in communication with an internal return cavity 3300 of the second end housing. In the internal cavity of the second end housing, fluid exiting from the plurality of first channels fills the cavity and experiences turbulent flow, and enters the open ends of the second plurality of channels to flow in a return direction towards the first end of the heat exchanger core. As with the first heat exchanger core, the second heat exchanger core may be formed as an extrusion.

[0164] Referring to Figure 34 herein, there is illustrated schematically in perspective view a first end housing of the second heat exchanger which is attached to a first end of the second heat exchanger core. The first end housing 2802 comprises a first outer shell component 3401 ; a second outer shell component 3402 and an internal dividing wall 3403 located between the first and second outer shells. The first and second outer shells each comprise a fluid pipe 3404, 3405 respectively. Since the first and second outer shells are identical to each other they may be formed from the same moulding or casting. Alternatively if required 3404 and 3405 may be different in some areas. In one embodiment, the outer shells and internal divider plate 3403 are made of a plastics material and the first end housing may be fitted to the end of the second heat exchange core by means of a suitable adhesive, for example epoxy adhesive. In other variations, the first and second outer shells and/or the dividing plate 3403 may be cast from a metal material and attached to the end of the second heat exchange core either by an adhesive, or by soldering or brazing. Alternatively it may be sealed with a seal and clip. [0165] Each outer shell comprises a fluid connecting pipe or tube for connecting an inlet or outlet manifold to an external heat exchange fluid system. In the embodiment shown, the fluid pipes are arranged so as to connect with a fluid inlet and fluid outlet tube of a battery module thermal management system such that the central axes of the fluid connection pipes lie parallel to the main length of the heat exchanger, but the centres of the fluid pipes are offset either side of a main central plane which bisects the heat exchanger parallel to the first and second sidewalls.

[0166] Referring to Figures 34 to 41 herein, said first end housing of the second heat exchanger comprises a first outer shell component 3401 ; a second outer shell component 3402; a partition member 3403 located between said first outer shell and said second outer shell; said partition member dividing a space between said first outer shell and said second outer shell into a first cavity and a second cavity; said partition member 3403 comprising a first plurality of castellated manifold wall formations 3406 - 3416 arranged to seal across a plurality of said dividing walls extending between said first sidewall and said second sidewall of said heat exchanger core, said first plurality of wall formations for directing fluid between said first cavity and said first plurality of channels; and said partition member comprising a second plurality of castellated wall formations for directing fluid between said second plurality of channels and said second cavity.

[0167] An inner surface of the first outer shell component and an inner surface of the second outer shell component, together form an inner surface which has dimensions which slides over and fits closely around the outer surfaces of the first and second sidewalls and upper and lower walls of the end of the heat exchanger core so that the first end housing can be slid over an end of the first heat exchanger core and attached thereto. When attached to the heat exchanger core, the plurality of wall formations 3406 - 3416 of the partition member 3403 abut an end face of the first heat exchanger in a fluid tight manner, thereby dividing the channels of the first heat exchanger into a first set of channels which are in communication with the first cavity, and a second set of channels which are in communication with the second cavity. [0168] The partition member 3403 comprises a substantially flat plate member 3417 which divides between first and second manifold cavities within the end housing. At an open end of the end housing, the wall formations of the partition member are arranged into a plurality of wall portions which lie parallel to the main partition member but which are spaced apart from the main partition flat plate member 3403 to one side of the plate member; a second plurality of wall portions which lie parallel to the plate 3403 and are spaced apart from the flat plate member on a second, opposite side of the plate member; and a plurality of transverse wall portions, each of which lie on a transverse to the main planes on which the first and second pluralities of wall portions lie, so that the plurality of wall formations form a plurality of rectangular box structures open on one side and having walls on three sides.

[0169] The plurality of internal partition wall formations 3406-3416 in said end housing are recessed relative to the open mouth of the end housing so that one end of the heat exchange core can slide into the open mouth of the end housing and locates between the outer shell walls of the end housing such that the end of the heat exchange core meets the plurality of manifold wall formations within the end housing, the configuration of the dividing walls inside the end housing determining which channels are designated first channels having a first flow direction, and which channels are designated as second channels having a second flow direction. The end of the heat exchange core slides into the open mouth of the end housing so that a portion of the outer surface of the first sidewall, a portion of the outer surface of the second side wall, an outer surface of portions of the upper and lower connecting walls, contact the inside surfaces of the outer shells of the end housing, and such that the ends of the first and second sidewalls and the ends of the connecting walls lie immediately opposite ends of the manifold wall formations, the ends of the manifold wall formations being recessed / inset in the end housing in the length direction relative to the end of the open mouth formed by the outer shell walls of the end housing. [0170] Referring to Figure 35 herein, there is illustrated schematically in exploded view the first end housing of the second heat exchanger showing in more detail the central partition plate 3403 which divides an internal cavity between the first and second outer shells into first and second fluid chambers, each comprising a manifold.

[0171] Referring to Figure 36 herein, there is illustrated schematically in exploded view the first end housing of the second heat exchanger showing the inlet chamber or cavity and outlet chamber or cavity and the central partition plate 3403 and the plurality of wall formations which direct fluid from the inlet fluid chamber and to the outlet fluid chamber.

[0172] Referring to Figure 37 herein, there is illustrated schematically the first end housing in end view, showing the first and second outer shells and the central partition plate 3403, showing a plurality of apertures defined by the plurality of wall portions of the partition plate which separate the fluid flow into a first set of fluid flows in a first outward or flow direction, and a second set of fluid flows in a second, or return direction, in which a first set of apertures connect with said inlet fluid chamber or cavity, and a second set of apertures connect with said fluid outlet chamber or cavity.

[0173] Referring to Figure 38 herein, there is illustrated schematically a first end of the second heat exchanger in view from above showing a plane C-C through the first end housing.

[0174] Referring to Figure 39 herein, there is illustrated schematically in in cut away view from one side, the first manifold of the first end housing of the second heat exchanger, along the section plane C-C, showing the plurality of box formations 3406 - 3416 comprising the partition wall, which connect with a corresponding plurality of channels of the end of the second heat exchanger core with the odd numbered box formations

[0175] Referring to Figure 40 herein, there is illustrated schematically a first end of the second heat exchanger showing a plane B-B through the second manifold of the first end housing. [0176] Referring to Figure 41 herein, there is illustrated schematically in cutaway view from one side the second manifold of the first end housing of the second heat exchanger along the section plane B-B, showing the plurality of box formations 3406- 3416 from the other side of the partition plate. The second channels correspond with the even numbered box formations.

[0177] Referring to Figure 42 herein, there is illustrated schematically in cut away view a section of a third heat exchanger core according to a third specific embodiment heat exchanger. The third embodiment heat exchanger has all of the features of the second embodiment heat exchanger as hereinbefore described, but with the modification that inside each coolant channel a plurality of connecting walls 4201 - 4210 extending between a first side wall of the heat exchange core and a second side wall of the heat exchange core, are each provided with one or a plurality of protruding fins each of which extend along the entire length of the heat exchange core, and first sidewall 4211 and second side wall 4212 are each provided with one or a plurality of elongate fins on an inner surface of said respective side wall which extend along a length of the core and which extend into the fluid channel enclosed by said first and second sidewalls and said dividing walls and/or upper and lower end walls 4213, 4214. Each individual fin protruding form a dividing wall extends in a direction substantially parallel to a plane of a first and/or second sidewall of the third heat exchanger core, along a length and width of the heat exchange core, such that each fin protrudes into the coolant flow of a coolant channel. The fins provide an additional surface area through which heat may be exchanged between the material of the third heat exchange core and the coolant fluid, compared to the situation where the inner surface of each channel is a substantially rectangular tube. In the embodiment shown, for each coolant channel, there are four individual fins protruding from the upper and lower dividing walls bordering the channel extending into the channel and extending from the dividing wall portions of the channels towards the central area of the channel, with two fins protruding from a first, upper connecting wall of each channel, and two fins protruding from a second, lower connecting wall of each channel. Additionally, depending upon the size of the channel, in each channel, extending from first sidewall 421 1 there are provided one or more fins, in the example shown either two or three, extending from an internal surface of the first sidewall and projecting into the channel. Similarly, for each channel, there are provided one or more fins extending from an inner surface of the second side wall 4212 into the channel.

[0178] The internal fins increase the surface area of metal of the first sidewall, second side wall and upper and lower dividing walls each channel which is in contact with fluid compared to a channel which does not have such fins.

[0179] In cross-sectional view in a direction looking along the main axial length of the core, each fin comprises a substantially“U” or dome-shaped then having a first sloping side, a second slope side and a rounded or domed curve connecting the distal ends of the first and second sloping sides. A base portion of each fin which is nearer the substantially flat outer surface of the sidewall or dividing wall is wider than the distal tip of the fin.

[0180] Referring to Figure 43 herein, there is illustrated schematically in more detailed view a single channel of the third heat exchanger core, showing for each internal coolant channel a plurality of heat exchange fins, each said protruding from the interior wall surfaces inside the heat exchanger core into an adjacent coolant channel.

[0181] Referring to Figure 44 herein, there is illustrated schematically in cut away view from a first end the central heat exchange core and a second end housing of the third heat exchanger, showing the plurality of fin structures internal to each coolant channel.

[0182] As will be understood by the person skilled in the art, the modification of fins internal to the fluid channels as shown in Figures 42 - 44 herein may be applied to the first, second and/or third heat exchanger core as described herein and are not restricted to use with the third heat exchange core.

[0183] Referring to Figure 45 herein, there is illustrated schematically a third battery pack arrangement comprising two rows of individual electrical energy cells, each of which is rectangular in shape. A first row of energy cells 4500 is arranged in parallel and spaced apart from a second row 4501 of energy cells. Each individual energy cell comprises a body having a first side face, a second side face, a first end face, a second end face, and upper face and a lower face. The first end face of each cell comprises an anode and a cathode, for connecting the energy cell to a respective anode bus and their respective cathode bus.

[0184] First row of electrical energy cells 4500 comprises a first plurality of cells each arranged side-by-side in a row, with the first end faces of the cells pointing outwardly. All of the first end faces of the first row of cells lie substantially on a first plane, and all of the second end faces of the first row of cells are arranged along a second plane, wherein the first and second planes are parallel to and spaced apart from each other, with the bodies of the first electrical energy cells extending between the first and second planes.

[0185] The second row 4501 of electrical energy cells are arranged in mirror- image with their second ends lying on a third plane and their first ends lying on a fourth plane, the fourth plane being spaced apart from the third plane and the bodies of the second row of electrical energy cells line between the third and fourth planes, wherein the third plane is spaced apart from and parallel to the second plane, there being a passageway, or gap there-between; and the first ends of the second row of cells, upon which the anodes and cathodes of the second cells are located faces outwardly of the battery pack, so that the general arrangement of the two rows of energy cells is that the gap or aisle in the middle is bounded by the second ends of the energy cells, which did not have anodes or cathodes, and the anodes and cathodes are placed facing outwardly of the battery pack, lying on the first plane and the fourth plane.

[0186] Referring to Figure 46, there is illustrated schematically the third battery pack of Figure 45 in view from one side, showing a plurality of first end faces of the individual electrical energy cells.

[0187] Referring to Figure 47 herein, there is shown the third battery pack in view from above, showing first and second rows of electrical energy cells, with a gap there-between. [0188] Referring to Figure 48 herein, there is illustrated schematically the first and second rows of the third battery pack in view from one end, showing the sides of the individual electrical energy cells and the passageway or aisle there-between.

[0189] Referring to Figure 49 herein, there is illustrated schematically the third battery pack having the first embodiment heat exchanger inserted in the central aisle or passageway between first and second rows of battery cells. In this arrangement, each of the second end faces of the individual electrical energy cells of the first row, are located in thermal contact with a first side face of the heat exchanger core.

[0190] The second end faces of the first plurality of electrical energy cells of the first row 4500 are each in close thermal contact with the outer surface of a first sidewall of the heat exchanger core, so that the outer surface of the sidewall is partitioned into a plurality of areas or regions, each facing immediately opposite to a second end face of a corresponding respective electrical energy cell. The electrical energy cells are stacked vertically in domino style in a row, and the internal fluid channels of the heat exchange core run along the row transverse to the main height direction of each individual electrical energy cell, so that the second end face of each electrical energy cell faces opposite the corresponding respective partition area on the outer surface of the first sidewall of the heat exchange core, wherein a plurality of said partition areas extend in a row along a main length of the heat exchanger core, each individual partition area extending substantially full height of the heat exchanger core, and on the opposite side of the first sidewall which is internal to the heat exchange core run the plurality of heat exchange fluid channels so that each partition area on the outer surface of the first sidewall corresponds to one or a plurality of inner channel surface areas on the inside of the first sidewall in which heat exchange fluid flows in a first direction, and one or a plurality of inner channel surface areas of the first sidewall in which heat exchange fluid flows second, opposite direction. The main length of the channels lie substantially transverse to a main height direction of the end surface or face of each electrical energy cell.

[0191] The heat exchanger shown in Figure 49 may be the first embodiment heat exchanger as described herein, having ten individual heat exchange fluid channels arranged in parallel top to bottom as shown in Figure 49 in which case there are five heat exchange fluid channels with heat exchange fluid flowing in a first direction and five channels containing heat exchange fluid flowing in a second, opposite direction. Alternatively, the second embodiment heat exchanger as described herein may be used, in which case there are nine relatively larger cross- sectional area heat exchange channels consisting of four channels having heat exchange fluid flowing in a first direction and five channels having heat exchange fluid flowing in a second direction, with two outermost channels of relatively reduced cross-sectional area having heat exchange fluid flowing in the first direction. As described elsewhere in this document, the fluid supply to the inlet and outlet may be swapped over, so that the flow direction of the first channel may be reversed, and likewise, the flow direction of the second channel may be reversed, but the first channels always have a fluid flow in an opposite direction to the second channels however the external heat exchange fluid is to supply is connected to the inlet and outlet tubes.

[0192] In a variation of the third battery pack, the battery pack may consist of only one row of electrical energy cells, for example either the first row or the second row as shown in Figure 49 so that the second ends of the individual energy cells in the row are located immediately adjacent a side face of the heat exchange core, so that the second ends of the electrical energy cells are in close thermal contact with the side of the heat exchanger’s core and so that the second end face of each electrical energy cell lies adjacent an area of the outer surface of the sidewall of the core which, on the opposite side of the sidewall inside the heat exchanger core there is located at least one first channel carrying heat exchange fluid in a first direction and at least one second channel carrying heat exchange fluid in a second direction opposite to the first direction.

[0193] Referring to Figure 50 herein, there is illustrated schematically a first flow path configuration of a heat exchanger disclosed herein, which has an overall “U” shaped fluid flow paths. In the flow path of Figure 50, heat exchange fluid enters a first chamber 5000 being an inlet manifold at a first end of the heat exchanger, passes through one or a plurality of first fluid flow channels 5001 in the heat exchanger core, wherein said fluid flows in a first direction between a first end and a second end of the heat exchanger, and the first fluid channels outlet into a first chamber 5002, being a return manifold, at a second end of the heat exchanger. Fluid in the return chamber 5002 experiences turbulent flow within the chamber at the second end, and enters one or a plurality of second channels 5003 through which the fluid passes in a second, return flow direction from the second end to the first end of the heat exchanger. At the first end of the heat exchanger, the one or plurality of second channels outlet into a second chamber 5004 being an outlet manifold, at the first end of the heat exchanger.

[0194] The flow path configuration of Figure 50 shows schematically three fluid flow path in a first direction and three fluid flow paths in a second direction, where the first channels are grouped together and the second channels are grouped together. However in practice, the fluid flow in the first direction may be distributed over a plurality of first fluid flow channels which are arranged across the width of the central heat exchanger core so that the individual first fluid channels are interleaved with and alternate with individual second fluid flow channels so that each first channel is adjacent at least one second channel, and at least one second channel is located adjacent at least one said first channel.

[0195] In the substantially “U” shaped flow arrangement, both the inlet manifold and the outlet manifold are at a same end of the heat exchanger as each other. The arrangement shown in Figure 50 shows a single flow pass of heat exchange fluid in a first direction from the first and second end, and a single flow pass of heat exchange fluid from the second end to the first end, with each pass being distributed amongst one or a plurality of individual channels where channels of the first fluid flow direction are interleaved and alternated with channels of the second fluid flow direction, so that the fluid flow traverses back and forth in opposite directions along a main length of the core of the heat exchanger. This arrangement is convenient where the piping and fluid flow connections to the remainder of the thermal management system need to be at one end of the heat exchanger. [0196] Referring to Figure 51 herein there is illustrated schematically a second fluid flow arrangement of a heat exchanger as disclosed herein, in which the overall fluid flow is in a substantially“S” shaped path between a first end housing 5100 and a second end housing 5102, through a central heat exchanger core 5101 such that fluid introduced into the heat exchanger at a first end exits the heat exchanger at a second end. In this arrangement, there is a contraflow of heat exchange fluid so that the heat exchange fluid traverses back and forth in opposite directions along a main length of the heat exchange core.

[0197] In the“S” shaped flow arrangement, an inlet manifold 5103 is located at first end housing 5100 of heat exchanger 5101 and a first return chamber 5104 is located at second end housing 5102 of the heat exchanger, with the fluid flowing along a length of the heat exchanger core between the inlet manifold 5103 and the first return chamber 5104.

[0198] Fluid enters a first inlet manifold chamber 5103 of the first end housing 5100 at a first end of the heat exchanger, and enters the inlet of one or a plurality of a first set of first fluid channels 5105 extending between the first end housing 5101 and second end housing 5102, and exits the first channels into first return chamber 5104 of the second end housing. The fluid exits the first return chamber 5104 being a return manifold of the second end into one or a plurality of second channels 5106, and flows in the opposite flow direction to the fluid flow in the first channels from the second end housing to the first end housing. The second fluid channels outlet into a second return chamber 5107 being a return manifold at the first end of the heat exchanger, where the second chamber at the first end is isolated from the first chamber so that at the first end housing there is no fluid flow between the first inlet manifold chamber and the second return manifold chamber 5107 other than via the central heat exchanger core 5101. Fluid entering the second return chamber 5107 is forced under pressure into the first ends of one or a plurality of third fluid channels 5108 which extend between the first and second ends of the heat exchanger core. Fluid flows in the third channels in the first direction (or first channel outlet flow channels) between the first end and the second end and outlets into the outlet manifold 5109 of the second end housing, with the result that the fluid flow follows three traverses of the heat exchanger core, a first traverse being through one or a plurality of first channels from the first chamber (inlet manifold) of the first end housing to the first return chamber of the second end housing, a second traverse being through one or a plurality of second channels 5106 from the first chamber of the second end to the second return chamber of the first end, and a third traverse being through the one or plurality of third channels 5108 from the second return chamber of the first end to the second chamber (outlet manifold 5109) of the second end. The fluid flow finally outlets the heat exchanger via an outlet pipe of the second chamber, outlet manifold, of the second end. In this arrangement, the overall fluid flow enters via an inlet pipe at the first end and exits the heat exchanger via an outlet pipe at the second end.

[0199] The fluid flow as externally connected to the heat exchanger of Figure 51 may be reversed, so that the inlet pipe becomes the outlet pipe and vice versa the outlet pipe becomes the inlet pipe in which case fluid flow will be the in the opposite directions as shown in Figure 51 herein. That is, when connected in a reverse flow direction configuration, heat exchange fluid enters the second chamber 5509 at the second end, enters the one or plurality of third channels 5108 at the second end and flows from the second end to the first end, discharging into the second return chamber 5107 of the first end housing. From the second return chamber 5107 of first end housing 5100, the fluid flows through the one or plurality of second channels 5106 from the first to second end to discharge into the first return chamber 5104 of the second end housing 5102, and from the first return chamber 5104, the fluid flow enters the second ends of the one or plurality of first channels 5105 and flows along those channels towards the first chamber 5103 at the first end housing. The heat exchange fluid is outlet from the first chamber 5103 of the first end housing.

[0200] In the arrangement shown in Figure 51 herein, the first, second and third channels are interleaved with each other so that across a width of the heat exchange core the flow directions in successive channels starting from one side of the heat exchange core and moving to the other side of the heat exchange core alternate with each other. Each individual second fluid channel is bounded on at least one side by a first fluid channel (either inlet or outlet flow) which has an opposite flow direction,. The arrangement of Figure 51 may be laid out as a plurality of substantially internally identical channels arranged into three sets each extending across the width of the heat exchanger core, each channel having substantially the same cross- sectional area when viewed in a direction transverse to the main flow direction or length of the channel.

[0201] Alternatively, the fluid flow arrangement of Figure 51 may be implemented by three sets of channels selected from a heat exchanger core arrangement are shown in Figures 30 - 32 herein in which a plurality of channels of differing cross-sectional areas in a direction perpendicular to the flow direction are provided.

[0202] In each of the first and second embodiment heat exchangers, including their variants, a heat exchanger for regulating the temperature of a plurality of electrical energy cells comprises an inlet manifold; an outlet manifold; a heat exchanger core having a first end and a second end; a plurality of first flow channels each extending between said first and second ends; a plurality of second flow channels each extending between said first and second ends; wherein said first plurality of channels have a first flow direction and said second plurality of channels have a second flow direction, said first flow direction being opposite to said second flow direction; wherein there is at least one of said first inlet flow channel and/or one of said second flow channels and/or one of said first outlet flow channels positioned adjacent to each anode of the plurality of electrical energy cells; and an outer surface of the side of the exchanger core is partitioned into a plurality of rows which correspond with the area occupied by the anode footprint of a row of battery cells; and for each said projected partition area of the outer surface of the heat exchanger core, underlying or behind that partition area, there is at least one fluid channel having heat exchange fluid flow in a first direction, and/or at least one fluid flow channel having fluid flow in a second and opposite direction and/or one of said first outlet flow channels [0203] Referring to Figure 52 herein, there is illustrated schematically in perspective view a battery pack 5200 comprising a single row of substantially rectangular tile or slab shaped energy cells arranged side-by-side in a row, having their relatively smaller surface area ends aligned along a plane. Each individual battery cell has a first side, a second side, a first end, a second end, an upper side and a lower side, each side having a corresponding respective surface. The first and second sides are parallel to each other. The first and second ends are spaced apart from each other and are parallel to each other and are perpendicular to the first and second sides. The upper and lower sides are spaced apart from each other, are parallel to each other, and are perpendicular to the first and second sides and perpendicular to the first and second ends. The anode and the cathode of each battery cell can both reside on a same end surface, or on opposite said end surfaces, or one contact being on one end surface and another contact being on either the upper or lower surface.

[0204] In the arrangement shown, an end surface of each battery cell overlies a corresponding respective projected partition area on an outer surface of the heat exchanger core so that along the heat exchanger core there are a plurality of said partition areas arranged in a row, each said partition area extending across a width of the heat exchanger core and lying across a plurality of first and second channels of said heat exchanger core, said channels running lengthwise along a main length of said row, said channels extending parallel to a main plane of said end face, said main plane bisecting said plurality of channels; said main plane bisecting each of said channels lying perpendicular to a plurality of planes each coinciding with a first side or second side of said plurality of battery cells.

[0205] The heat exchanger as shown in Figure 52 has fluid inlet and outlet tubes both at one end of the heat exchanger. In other embodiments, the heat exchanger may have a fluid inlet at an opposite end of the heat exchanger to the fluid outlet. First and second channels running either in a“U” shaped flow path, or in an overall “S” shaped flow path as described herein encounter a plurality of partition areas along a length of said heat exchanger core, so that each partition area transfers heat with fluid running in at least one said first channel and with fluid running in an opposite direction in at least one said second channel.

[0206] Referring to Figure 53 herein, there is illustrated schematically in perspective view a heat exchanger as disclosed herein, for regulating the temperature of a battery pack comprising first and second stacks of battery cells, each said stack comprising four rows or layers of individual battery cells, each said row or layer comprising a plurality of substantially circular cylindrical battery cells each having an anode at one end and a cathode at another end. In the arrangement shown the heat exchanger lies adjacent the anode ends of the battery cells, these tending to generate greater heat than the cathode ends under conditions of charge or discharge.

[0207] In the arrangement shown, each stack comprises four rows of battery cells, each row having 59 individual battery cells such that a stack comprises 236 battery cells and the battery pack comprises 472 individual battery cells, wherein one end of each said battery cell has its temperature regulated by the heat exchanger as shown.

[0208] The individual battery cells are arranged having their main central length axes on a square grid pattern such that each individual battery cell touches at maximum four adjacent battery cells. One end of each battery cell faces opposite a portion of surface area of a core of said heat exchanger on an outer surface of said heat exchanger core, behind which are located at least one first fluid channel for carrying fluid in a first flow direction and at least one second fluid channel for carrying fluid in a second, reverse or return flow direction, where the first and second flow directions are opposite to each other.

[0209] Referring to Figure 54 herein, there is illustrated schematically in perspective view a fourth embodiment heat exchanger 5400. The fourth heat exchanger comprises a central heat exchanger core 5401 ; a first end housing 5402 at a first end of the heat exchanger core; and a second end housing 5403 at a second end of the heat exchanger core. The first end housing has a fluid connection tube or pipe 5404 and the second end housing has a fluid connection pipe 5405. The first end housing may be designated as an inlet manifold for inlet of heat exchange fluid and the second end housing may be designated as an outlet manifold for outlet of heat exchange fluid, or alternatively if the flow direction is reversed, the second end housing becomes the inlet manifold and the first end housing becomes the outlet manifold. For ease of description the general flow direction will be described where the first housing is the inlet manifold and the second housing is the outlet manifold, but the skilled person would appreciate that the direction may be reversed and the description hereunder modified accordingly corresponding to the reversal of flow direction.

[0210] The fourth heat exchanger shown comprises an overall“S” flow path heat exchanger in which fluid enters the heat exchanger at a first end, traverses a whole length of the heat exchanger core and reverses direction at the second opposite end, traverses the whole length of the heat exchanger core from the second end to the first end; reverses flow direction at the first end and traverses the whole length of the heat exchanger core again from the first end to the second end, so that the heat exchange fluid makes at least three passes between the first and second ends of the heat exchanger.

[0211] Referring to Figure 55 herein, there is shown schematically the fourth heat exchanger of Figure 54 herein in view from one end. In the arrangement shown, the fluid connection tube is at opposite ends of the heat exchanger core and are each arranged on a same side of the heat exchange core.

[0212] Referring to Figure 56 herein, there is illustrated schematically the fourth heat exchanger in view from one side. The fluid connection tubes are arranged on the same side as each other across a width of the heat exchanger core, where the width direction is transverse to the length direction and lies in a plane which is parallel to a plane which bisects each of the internal fluid channels.

[0213] In a variation of the fourth heat exchanger of Figure 56 herein, the fluid connection tubes may be arranged on opposite sides of the central heat exchanger core to each other. [0214] Referring to Figure 57 herein, there is illustrated schematically in view from above the fourth heat exchanger of Figure 54.

[0215] Referring to Figure 58 herein there is illustrated schematically in cut away view a section along a plane N - N which bisects the heat exchanger core parallel to a main outer side surface of the heat exchanger core. Shown in Figure 58 along a main length of the heat exchanger core there are arranged ten individual fluid channels arranged into at least three sets, wherein a first set of channels carries fluid between a first end of the exchanger core and a second end of the heat exchanger core; a second set of channels carries fluid between the second end of the heat exchanger core and the first end of the heat exchange core; and a third set of channels carries fluid from the first end of the exchanger core to the second end of the exchange core, in which the first and third channels are not in direct fluid connection to each other, but in the flow path direction, are connected to each other via said second set of channels, so that in the direction of fluid flow the fluid traverses through a first manifold chamber of the first end housing and is distributed into the first set of channels; traverses across the length of the heat exchanger core through the first set of channels; from the first set of channels, the fluid flows into a first return manifold chamber of the second end housing; from the first return manifold chamber of the second end housing, the fluid flows into the second set of channels and traverses from the second end of the heat exchanger core to the first end of the exchanger core, so as to flow into a second chamber of the first end housing; the fluid flows from the second chamber of the first end housing into the inlets of the third set of channels and traverses from the first to second ends of the heat exchanger core through the third channels; and at the outlet of the third channels the fluid flows into a second (outlet manifold) chamber of the second end housing and thereafter flows out of the second manifold chamber of the second end housing through a fluid connection pipe.

[0216] As mentioned above, if the flow direction is reversed, so that fluid enters the heat exchanger at the second end housing and outlets the heat exchanger at the first end housing, the overall the flow path remains the same, but the flow direction is reversed.

[0217] Referring to Figure 59 herein, there is illustrated schematically a first end housing 5402 of the fourth heat exchanger. The first end housing comprises first outer shell component 5901 ; second outer shell component 5902; internal partition plate 5903; and a fluid connection pipe 5404 for connecting fluid to the end housing.

[0218] Referring to Figure 60 herein, there is shown the first end housing of the fourth heat exchanger in exploded view. The first end housing comprises first outer shell casing 5901 and second outer shell casing 5902 which close together to form a partially enclosed chamber there-between, and a central partition plate member 5903 which lies between the first and second outer shells in the chamber therein; said partition member dividing the internal space between the first and second outer shells into a first manifold chamber and a second manifold chamber; said first and second manifold chambers having openings defined by a wall structure 5904. The central plate member 5903 comprises a flat central plate 5905 having first and second sides; and along a front edge of said central plate there is provided the wall structure 5904 which has end faces which correspond with the end faces of the outer sidewalls of the heat exchange core and the end faces of the dividing walls of the heat exchanger core so that when the first end housing is fitted over one end of the fourth heat exchanger core, the end faces of the wall structure 5904 meet and abut with the end faces of the outer sidewalls, upper end walls and lower end walls and dividing walls of the heat exchanger core. The dividing walls 5904 of the partition member 5903 comprise a first set of end faces 5906 - 5909 lying on a plane parallel to a main plane bisecting the partition member 5903, said first set of end faces lying on a first plane parallel to and offset from said plane bisecting the partition member; a second set of end faces 5910 - 5912 lying on said plane parallel to a main plane bisecting the partition member 5903 and said second set of end faces lying on a second plane offset from said plane bisecting said partition member; and a third set of end faces 5913 - 5920, said third set of end faces lying on said plane perpendicular to said plane bisecting the partition member and extending in a direction substantially perpendicular to a main length direction of said first end faces and said second end faces. The main length of each of the plurality of first end faces lie parallel to the main length of each of the plurality of second end faces and perpendicular to the main lengths of each of the third set of end faces.

[0219] The core of the fourth heat exchanger is identical to the core of the first heat exchanger as hereinbefore described. The first end housing 5402, in combination with the second end housing 5403 divides the plurality of ten channels of the heat exchanger core into at least three sets of fluid channels as described herein above, which causes the fluid to flow in an overall“S” pattern to and fro across the main length of the heat exchanger core. If the total number of channels is not a multiple of three then a first channel or channels can be used in conjunction with the S flow. For example the 10 channel heat exchanger core will have 3 S flow paths giving 9 channels and a single first channel to make up to a total of ten channels.

[0220] Referring to Figure 61 herein, there is illustrated schematically the second end housing 5403 of the fourth heat exchanger. The second end housing comprises first outer shell 6100; second outer shell 6101 ; and an internal partition member 6102. The first and second outer shells 6100, 6101 form an enclosed space which is divided by the internal partition member 6102, and which has a single large opening having an internal shape which corresponds to an external shape of the core of the fourth heat exchanger, so that the second manifold can slide over the end of the heat exchanger core.

[0221] Referring to Figure 62, there is shown the second end housing of the fourth heat exchanger in exploded view. The internal partition member 6102 comprises a substantially flat partition plate having at one end a wall structure. The substantially flat partition plate is defined between a first plane parallel to a first outer surface of the partition plate and a second plane parallel to a second outer surface of the partition plate. At one end of the partition wall a plurality of wall portions extend outwardly beyond the first and second parallel planes to form a plurality of inlet and outlet apertures for connecting with the ends of the channels of the heat exchanger core when the partition plate is located inside the first and second outer shell members 6100, 6101.

[0222] A first dividing wall structure 6204 provides an aperture which, extends across first and second core channels and when divided by a dividing wall of the heat exchanger core forms an outlet from a first core channel of the heat exchanger and an inlet to a second adjacent core channel of heat exchanger. A second dividing wall structure 6205 has an aperture which spans the cross-sectional areas of three core channels, being the third, fourth and fifth core channels counted from one side of the heat exchanger core. When divided by the dividing walls of the heat exchanger core, the second wall structure provides an outlet from a third channel, an outlet from a fourth core channel, and an outlet from said fifth core channel of the heat exchanger core. A third dividing wall structure 6206 in combination with the dividing walls of the heat exchanger core spans across the cross-sectional areas of the sixth and seventh core channels. In combination with the heat exchanger core dividing walls either side of the sixth and seventh core channels, the third dividing wall structure provides an inlet to a sixth core channel, and an outlet to a seventh core channel. A fourth dividing wall structure 6207 provides an inlet to an eighth core channel. A fifth dividing wall structure 6208 spans across the cross-sectional areas of the ninth and tenth core channels and provides an inlet to a ninth core channel and an outlet to a tenth core channel.

[0223] The aperture defined by the first dividing wall structure 6204, the aperture defined by the third wall structure 6206 and the aperture defined by the fifth wall structure 6508 are each in communication with a first cavity or chamber 6209 between the partition member and the second outer shell 6101 ; and the aperture defined by the second wall structure 6205, and the aperture defined by the fourth wall structure 6207 are each in communication with a second chamber between the partition member 6102 and the first outer shell 6100.

[0224] The second chamber is in communication with a fluid connection tube 5405 to which an external fluid pipe network can be attached. [0225] Referring to Figure 63 herein, there is illustrated schematically in perspective view a fifth heat exchanger 6300 according to a fifth specific embodiment, having a fifteen channel core, of which the two outermost channels have a reduced cross sectional area in the direction perpendicular to the length of the channels compared to the inner most channels which are all for equal cross sectional area to each other. The fifth heat exchanger comprises a central heat exchanger core 6301 ; a first end housing 6302; at a first end of the heat exchanger core; and a second end housing 6303 at a second end of the heat exchanger core. The first end housing has a first fluid connection tube or pipe 6304 and the second end housing has a second fluid connection pipe 6305. The first end housing may be designated as an inlet manifold for inlet of heat exchange fluid and the second end housing may be designated as an outlet manifold for outlet of heat exchange fluid, or alternatively if the flow direction is reversed, the second end housing becomes the inlet manifold and the first end housing becomes the outlet. For ease of description the general flow direction will be described where the first end housing is the inlet manifold and the second end housing is the outlet manifold, but the direction may be reversed and the description hereunder modified accordingly corresponding to the reversal of flow direction.

[0226] The fifth heat exchanger shown comprises an overall“S” flow path heat exchanger through a central heat exchanger core having fifteen individual flow channels, in which fluid enters the heat exchanger at one end, traverses a whole length of the heat exchanger core and reverses direction at the second, opposite end, traverses the whole length of the heat exchanger core from a second end to the first end, reverses flow direction at the first end and traverses the whole length of the heat exchanger core from the first end to the second end so that the heat exchange fluid mostly makes three passes between the first and second ends of the heat exchanger.

[0227] Referring to Figure 64 herein, there is shown schematically the fifth heat exchanger of Figure 63 herein in view from one end. In the arrangement shown, the first and second fluid connection tubes are at opposite ends of the heat exchanger core and are each arranged on a same side of the heat exchange core.

[0228] Referring to Figure 65 herein, there is illustrated schematically the fifth heat exchanger in view from one side. The fluid connection tubes are arranged on opposite sides to each other across a width of the heat exchanger core, where the width direction of the core is transverse to the length direction and lies in a plane which is parallel to a plane which bisects each of the internal fluid channels.

[0229] Referring to Figure 66 herein, there is illustrated schematically in view from above the fifth heat exchanger of Figure 63.

[0230] Referring to Figure 67 herein there is illustrated schematically in cut away view a section along a plane 0 - 0 which bisects the heat exchanger core of the fifth heat exchanger parallel to a main outer side surface of the heat exchanger core. Shown in Figure 67 along a main length of the heat exchanger core there are arranged fifteen individual fluid channels arranged side by side with each other across a main width of the heat exchanger core between first and second sidewalls, in a single layer of channels, with dividing walls separating the individual channels from their immediately adjacent neighbours, the dividing walls extending between the first and second side walls. The channels may be of differing cross-sectional areas to each other in order to optimise the heat transfer capacity at any region on the surface area of the outer surfaces of the side walls to suit any particular pattern of battery cell end surfaces. The objective of varying the channel cross sectional areas is to even out as much as possible the temperature over both the length and width of the core.

[0231] The plurality of channels are arranged into a first set of channels which carries fluid in a first direction parallel to the main length axis of the fifth heat exchanger core, and a plurality of second channels which carries heat exchange fluid in a second and opposite direction, also parallel to the main length axis of the fifth heat exchanger core. The divider walls and upper and lower end walls of the core each extend between the first and second sidewalls and form connecting walls which connect the first sidewall to the second sidewall. [0232] A first set of channels carries fluid between a first chamber in the first end housing at a first end of the heat exchanger core. A second set of channels carries heat exchange fluid between a first return chamber at the second end housing at the second end of the heat exchanger and a second return chamber of the first end housing at the first end of the heat exchanger. A third set of channels carries heat exchange fluid between the second return chamber at the first end housing at the first end of the heat exchanger and a second chamber at the second end housing at the second end heat exchanger, the overall flow path being from the first end housing to the second end housing, from the second end housing back to the first end housing, and back again from the first end housing to the second end housing.

[0233] The first fluid connection pipe is connected to the first chamber of the first end housing and the second fluid connection pipe is connected to the second chamber of the second end housing, the first and second fluid connection pipes connecting the heat exchanger to an external heat exchange fluid circuit.

[0234] If the connections to the external fluid circuit are reversed so that the overall flow direction is reversed, so that fluid enters the heat exchanger at the second end housing and outlets the heat exchanger at the first end housing, overall the flow path remains the same, but the flow directions in each of the core channels described herein above with reference to the fifth heat exchanger are reversed.

[0235] Referring to Figure 68 herein, there is illustrated schematically a first end housing 6302 of the fifth heat exchanger. The first end housing comprises first outer shell component 6801 ; second outer shell component 6802; internal partition plate 6803; and a fluid connection pipe 6304 for connecting fluid to the manifold.

[0236] Referring to Figure 69 herein, first outer shell casing 6801 and second outer shell casing 6802 close together to form a partially enclosed chamber there between. Central partition plate member 6803 which lies between the first and second outer shells in the chamber therein, divides the internal space between the first and second outer shells into a first chamber and a second chamber; said first and second chambers having openings defined by a wall structure 6804. The central plate member 6803 comprises a flat central plate 6805 having first and second sides; and along a front edge of said central plate there is provided said wall structure 6804 which has end faces which correspond with and mirror the end faces of the outer sidewalls of the heat exchange plate and the end faces of the dividing walls of the heat exchanger core so that when the first manifold is fitted over one end of the fourth heat exchanger core, the end faces of the wall structure 6804 meet and abut with the end faces of the outer sidewalls, upper end walls and lower end walls and dividing walls of the heat exchanger core. The dividing walls of the partition member 6803 comprise a first set of end faces 6806 - 6810 lying on a plane perpendicular to a main plane bisecting the partition member 6803, said first set of end faces lying on a first plane parallel to and offset from said plane bisecting the partition member; a second set of end faces 681 1 - 6815 lying on said plane parallel to and offset from said plane bisecting the partition member, said second set of end faces lying on a second plane offset from said plane bisecting said partition member; and a third set of end faces 6816 - 6826, said third set of end faces lying on said plane perpendicular to said plane bisecting the partition member and extending in a direction substantially perpendicular to a main length direction of said first end faces and said second end faces. The main length of each of the plurality of first end faces lie parallel to the main length of each of the plurality of second end faces and perpendicular to the main lengths of each of the third set of end faces.

[0237] The core of the fifth heat exchanger is similar to the heat exchanger core of the second heat exchanger as hereinbefore described, but has a higher number of channels. The first end housing 6302 in combination with the second end housing 6303 divides the plurality of fifteen channels of the fifth embodiment heat exchanger core into at least three sets of fluid channels as described herein above, which causes the fluid to flow in and overall“S” pattern to and fro across the main length of the heat exchanger core.

[0238] Referring to Figure 70 herein, there is illustrated schematically the second manifold 6303 of the fifth heat exchanger. The second manifold comprises first outer shell 7000; second outer shell 7001 ; and an internal partition member 7002. The first and second outer shells 7000, 7001 form an enclosed space which is divided by the internal partition member 7002, and which has a single large opening having an internal shape which corresponds to an external shape of the core of the fifth heat exchanger, so that the second manifold can slide over the end of the heat exchanger core.

[0239] Referring to Figure 71 , there is shown the second manifold of the fifth heat exchanger in exploded view. The internal partition member 7002 comprises a substantially flat partition plate 7003 having at one end a wall structure 7004. The substantially flat partition plate is defined between a first plane parallel to a first outer surface of the partition plate and the second plane parallel to a second outer surface of the partition plate. At the side of the partition wall a plurality of wall portions extend outwardly beyond the first and second parallel planes to form a plurality of inlet and outlet apertures when the partition plate is located inside the first and second outer shell members 7000, 7001. Each wall structure comprises an open box section of three sides defining an aperture within the main substantially rectangular aperture defined by the first and second outer shell members.

[0240] Numbering the central core channels 1 to 15 from top to bottom as shown in Figures 70 and 71 , a first dividing wall structure 7105 provides an aperture which, extends across first core channel 1. A second dividing wall structure 7106 forms a second aperture which extends across the ends of the second and third core channels 2 and 3. A third wall structure 7107 forms an aperture which extends across an open end of the fourth core channel 4. A fourth wall structure 7108 defines an aperture which extends across the open ends of the fifth and sixth core channels 5 and 6. A fifth wall structure 7109 forms an aperture which meets up with the open end of the seventh core channel 7. A sixth wall structure 7110 forms an aperture which spans across the open ends of the heat and ninth core channels 8, 9. A seventh wall structure 711 1 forms an aperture which coincides with an open end of a tenth core channel 10. An eighth wall structure 71 12 forms an aperture which spans across the open ends of an eleventh and twelfth core channels 11 , 12. A ninth wall structure 71 13 forms an aperture which coincides with and matches the open end of a thirteenth core channel 13. A tenth wall structure 7114 forms an aperture which spans across the open ends of the fourteenth and fifteenth core channels 14, 15.

[0241] The aperture defined by the first dividing wall structure 7105, the aperture defined by the third wall structure 7107, the aperture defined by the fifth wall structure 7109, the aperture defined by the seventh wall structure 7111 , and the aperture defined by the ninth wall structure 71 13 are each in communication with a second cavity or chamber 71 15 between the partition member and the second outer shell7001 ; and the apertures defined by the second wall structure 7106, the aperture defined by the fourth wall structure 7108, the aperture defined by the sixth wall structure 7110, and the aperture defined by the eighth wall structure 71 12, and the aperture defined by the tenth wall structure 71 14 are each in communication with a second chamber between the partition member 7002 and the first outer shell 7000.

[0242] The second chamber of the second end housing is in communication with a fluid connection tube 6305 to which an external fluid pipe network can be attached.

[0243] Referring to Figure 72 herein, there is illustrated schematically in view from one side a sixth heat exchanger 7200. The sixth heat exchanger comprises a first end housing 7201 ; a central heat exchanger core 7202; and a second end housing 7203.

[0244] The sixth heat exchanger has all of the technical features of the first heat exchanger described herein before with the exception that the heat exchanger core has ten enclosed fluid channels, and at each of an upper and a lower side of the heat exchanger core 7202, there is a respective first and second air cooled channel as shown in Figure 73 herein. The first end housing 7201 and the second end housing 7203 are adapted for a ten channel arrangement.

[0245] In the foregoing, only the differences in construction between the sixth heat exchanger and the first heat exchanger will be described and it will be understood by the skilled person that the construction and operation of the sixth heat exchanger is the same as for the first heat exchanger in other respects. [0246] Referring to Figure 73 herein, there is shown schematically the core of the sixth heat exchanger in view from a first end. As the core is symmetric, a view from the second end corresponds to the view from the first end. The core has a first end, a second end, a width between the first and second ends and a thickness.

[0247] The heat exchanger core comprises a first side wall plate 7300; a second side wall plate 7301 ; the first and second side wall plates being arranged parallel to each other and spaced apart from each other; a plurality of partition walls 7302-7312, each said partition wall extending in a direction between said first and second ends and extending along a thickness of said core. Each of said plurality of partition walls is spaced apart from its nearest neighbour, such that said partition walls form a plurality of channels lying across the width of the heat exchanger core.

[0248] The channels are divided into a plurality of innermost channels 7313- 7322 outer channels 7323, 7324. Each outermost channel 7323, 7324 is bounded by an inner surface area of the first sidewall, and inner surface area of the second side wall and an inner surface area of an outermost dividing wall 7302, 7312 respectively, and forms an open channel into which atmospheric air can pass. The end faces of the first and second sidewalls and the plurality of connecting and/or dividing walls form a ladder like shape as viewed from one end of the heat exchanger core.

[0249] Each said inner channel is bounded by an internal surface area of the first side wall, an internal surface area of the second side wall, an internal surface area of a first dividing wall and an internal surface area of a second dividing wall, such that each said inner channel forms a tubular passage or channel extending from one end of the heat exchanger core to the other. In the example shown, there are ten inner fluid channels and two outer air channels. In use, the fluid channels are filled with heat exchange liquid and the outer channels are open to atmospheric air.

[0250] In use, the inner channels 7313-7322 are arranged for liquid flow in a contra flow arrangement comprising at least a first set of channels in which heat exchange fluid flows in a first direction and a second set of channels in which heat exchange fluid flows in a second opposite direction. The first set of channels are interleaved and alternate with the second set of channels, so that each second channel is adjacent at least one first channel, which enables heat transfer between heat exchange fluid flowing in a first direction and heat exchange fluid flowing in said second direction via heat conduction through the dividing walls. Heat transfer between the fluid flowing in the first and second channels and an outer surface of the first sidewall is by heat conduction through the material of the first sidewall. Similarly, heat transfer between fluid flowing in the first and second channels and an outer surface of the second side wall is by heat conduction through the material of the second side wall.

[0251] For the inner channels 7313, 7322 which lie adjacent the outermost channels, there is heat transfer between the liquid flowing in those outer ones of the inner channels, and their neighbouring air cooled channels 7323, 7324 respectively through the respective outermost dividing walls 7302, 7312 and parts of the first and second sidewalls which bound the outer channels 7323, 7324.

[0252] In the core of the sixth heat exchanger, the outermost dividing walls 7302, 7312 are each curved in the shape of an arch so that in cross-sectional area as viewed along with the length of the core the outermost ones 7313, 7322 of the inner channels each have the shape of an arched window as viewed in a direction perpendicular to a main length axis of said channels.

[0253] In the localized area where the end housings 7201 and 7203 attach over the said ends of the heat exchange core 7202 the outer channels 7323 and 7324 are removed. This gives a more simple cross section of the ends of the heat exchanger core to interface into the end housings, as in all the previously described heat exchangers.

[0254] Now shown in Figures 74 to 78 herein there is illustrated schematically five different flow paths for heat exchange fluid, each of which are of the“U” shaped type in which both in and out fluid connections to external heat exchange fluid system connect to a heat exchanger at the same end, so that the heat exchange fluid enters the heat exchanger at a first end housing, travels to the second end, the flow path is returned at the second end housing, and the fluid travels from the second end to the first end to be outlet at the first end. [0255] Referring to Figure 74 herein, there is illustrated schematically a simple “U” shaped flow path along first and second channels 7401 , 7402 where fluid passes from the first end to the second end through the first channel, is returned at the second end by a return manifold, and travels from the second end to the first end where the fluid drains or outlets from the first end housing. This basic unit may be replicated across the width of a heat exchanger core. A return manifold at the second end can either pair up individual first and second channels, or can be an open cavity in which the fluid discharged from multiple first channels mixes in turbulent flow and re-enters multiple second channels.

[0256] Referring to Figure 75 herein, there is shown a second variation of a “U” flow path arrangement in which heat exchange fluid enters and is discharged from the heat exchanger core at a first end, in which there are two channels of a first set of channels in the outward or flow direction which send heat exchange fluid from the first and second, and the single return channel of the second set which returns heat exchange fluid from the second end to the first end, in a return flow direction from where it exits the heat exchanger. In such an arrangement, the two flow direction channels of the first set make each have a flow capacity of 50% of the flow capacity of the single return channel.

[0257] Referring to Figure 76 herein, there is shown a third variation of a“U” flow path arrangement in which heat exchange fluid enters and is discharged from the heat exchanger core at a first end, and in which there are two channels of the first set carrying fluid in a first flow direction, and two channels of a second set carrying fluid from the second and first end in a return flow direction. At the second end, a return manifold may comprise a single open cavity in which fluid arriving from either of the channels of the first set can flow on the return path via either channel of the second set. Alternatively, the return manifold may pair one single channel of the first set with one single channel of the second set so that each flow channel of the first set is assigned to a corresponding respective return channel of the second set. In the third variation, channels of the first set are interleaved with channels of the second set so that each first channel is bounded by at least one second channel, and at least one of the second channels is bounded by two first channels and at least one of the first channels is bounded by two second channels.

[0258] Referring to Figure 77 herein, there is shown a fourth variation of a“U” flow path arrangement in which heat exchange fluid enters and is discharged from the heat exchange core at a first end, and in which there are two flow channels of the first set which carry heat exchange fluid from the first end to the second end, and two return channels of the second set which carry heat exchange fluid from the second end to the first end.

[0259] In the arrangement of Figure 77, the two return channels of the second set are located innermost across the width of the core and the two flow channels of the first set are located as the outermost channels, each first channel being bounded on one side by a second channel and on its other side by air.

[0260] Referring to Figure 78 herein, there is shown a fifth variation of a“U” flow path arrangement in which heat exchange fluid enters and is discharged from the heat exchange core at a first end, and in which there are two flow channels of the first set which carry heat exchange fluid from the first end to the second end, and two return channels of the second set which carry heat exchange fluid from the second end to the first end.

[0261] In the arrangement of Figure 78, the two return channels of the second set are located outer most across the width of the core and the two flow channels of the first set are located as the innermost channels, each second channel being bounded on one side by a first channel and on its other side by air; and each first channel being bounded on one side by a second channel, and on another side by a first channel.

[0262] Referring to Figure 79 herein, there is illustrated schematically a further flow path variation which is a combination of reciprocating“S” shaped flow paths and straight through end to end flow paths in a heat exchanger core having ten individual channels. Numbering the channels 1 to 10 from top to bottom are shown in figure 79, where each individual channel is shown by a horizontal line, the first, second and third channels are arranged in a first“S” path as hereinbefore described, where heat exchange fluid enters a first channel and travels from first end to a second end, is returned at the second end to flow back in a second channel from the second first and, is returned again at the first end to flow from the second channel into a third channel and back from the first end to the second end, where the fluid exits the heat exchanger. The fourth, channel is used as a straight through end to end flow from the first end to the second end. The fifth, sixth and seventh channels are used as an“S” path flow with fluid entering the seventh channel, flowing from the first end to the second end, the flow being returned at the second end by a return manifold, and flowing in the sixth channel from the second end to the first end, being returned by a return manifold at the first end to be returned via the fifth channel from the first end to the second end of the core.

[0263] Similarly, the eighth to tenth channels are arranged in an“S” flow path, in which heat exchange fluid enters the tenth channel and travels from the first end the second end, is returned at the second end and fed into the ninth channel from which it returns from the second end to the first end, and is returned again at the first end and fed into the eighth channel from which the fluid travels from the first end to the second end.

[0264] In the flow pattern of figure 79, ten substantially parallel channels are arranged as three“S” shaped flow paths and one straight through flow path. Two of the“S” shaped channels have a flow from an outer side of the core towards the centre of the core, across the width of the core. A third”S” shaped flow path having fluid entered in the seventh channel has fluid flowing from a position within the central body of the core to a position which is nearer the centre of the core, that is, in a direction towards the geometric centre of the width of the core.

[0265] Referring to Figure 80 herein, there is illustrated schematically in view from one end the core of a seventh heat exchanger having fourteen individual fluid channels. The seventh heat exchanger core has all construction or features of the first heat exchanger core as described herein before, but has fourteen internal channels. The seventh heat exchanger core is suitable for regulating the temperature of a battery having at least one stack comprising seven layers or rows of individual circular cylindrical battery cells, arranged either in a log pile arrangement, or in an arrangement where the main central axis of each battery cell lies at the intersections of lines in a square grid pattern. Alternatively it is suitable for a wider prismatic battery cell.

[0266] Figure 81 herein illustrates schematically a plane G - G which bisects the seventh heat exchanger core equidistantly between an outer face of a first sidewall 8100 and an outer face of a second side wall 8102, bisecting each of the fourteen individual channels.

[0267] Referring to Figure 82 herein, there is illustrated schematically a sectional view of the core of the seventh heat exchanger configured in a hybrid multiple flow path arrangement in which some channels have a“straight through” end to end flow path and other channels have an“S” channel flow path.

[0268] Numbering the channels from top to bottom as seen in Figure 82, channels 1 to 3 follow a first“S” shaped flow path in which fluid enters the first channel at the first end, passes to the second end of the core, is directed by a return manifold at the second end into the second end of the second channel, returns through the second channel to the first end and is directed by a return manifold at the first end into the third channel and traverses the length of the core to exit at the second end of the third channel. The flow path therefore flows from the outer part of the width of the core towards the inner section of the core.

[0269] The fourth channel is a straight through flow from the first end of the court of the second end. Although the width of this channel is shown to be the same as the other channels, in practice, to optimize heat transfer it may be narrower to restrict flow.

[0270] The fifth, sixth and seventh channels form a second“S” shaped flow path, with fluid entering the fifth channel at the first end of the core, being directed at the second end of the fifth channel by a return manifold at the second end of the core into the second end of the sixth channel; flowing from the second end of the sixth channel to the first end of the sixth channel; being directed by a second return manifold at the first end of the core into the first end of the seventh channel and traversing from the first end of the seventh channel to the second end of the seventh channel to be outlet at the second end of the core.

[0271] The eight to tenth channels are a replication of the flow path of the fifth to seventh channels, but laid out in an adjacent area across the width of the core.

[0272] The eleventh to thirteenth channels are a replication of the flow path of the fifth to seventh channels, but laid out in another area across the width of the core, adjacent the tenth channel.

[0273] The fourteenth channel is a straight through first end to second end flow path. Although the width of this channel is shown to be the same as the other channels, in practice, to optimize heat transfer it may be narrower to restrict flow.

[0274] The fluid flow paths through the heat exchanger core of the seventh heat exchanger are determined by the configuration of a first end housing and a second end housing (not shown in figure 82). The first end housing comprises an inlet manifold which connects a fluid connection tube for connecting to an external heat exchange fluid circuit with the first, fourth, fifth, eighth , eleventh and fourteenth channels and provides a return manifold for returning fluid from the second, sixth, ninth, and twelfth channels and redirecting that fluid into the third, seventh, tenth, and thirteenth channels.

[0275] The second end housing comprises an outlet manifold for connecting a second fluid connection tube to the second ends of the third, fourth, seventh, tenth, thirteenth and fourteenth channels, and providing a return manifold for connecting the second ends of the first, fifth, eighth, and eleventh channels to the second ends of the second, sixth, ninth, and twelfth channels.

[0276] Referring to Figure 83 herein, there is illustrated schematically in cut away view along the plane G - G from one side the heat exchanger core of the seventh heat exchanger showing the flow directions along fourteen channels in relation to a plurality of footprint areas shown as circles, where an outer surface of a side wall of the heat exchanger core lies in thermal contact with a plurality of battery cell end surfaces. In this example, a stack of seven layers or rows of battery cells are arranged in a log pile arrangement in which the circular cylindrical battery cells are arranged together in an optimally compact arrangement, with a main central length axis of each battery cell lying at the centre of a hexagon. The plurality of channels are arranged so that for each circular footprint area on the outer surface of a side wall of the heat exchanger, which is in thermal contact with an anode of a corresponding respective battery cell, said footprint area coincides lies opposite at least two fluid channels, said fluid channels being on an opposite side of said side wall to said battery cell.

[0277] In the arrangement shown, some of the rows of footprint areas overlie a pair of channels which have fluid flow in opposite directions, whilst some of the rows of footprint areas overlie a pair of channels having fluid flow in a same direction, but one is first pass and one is third pass through the core. However every row of footprint areas overlies at least one channel which carries fluid from an inlet end to an outlet end of said heat exchanger.

[0278] Numbering the rows of footprint areas 1 to 7 starting at the top of Figure 83, the first row of footprint areas overlies the first and second channels which have fluid flow in opposite directions to each other. The second row of footprint areas overlies the third and fourth channels which have fluid flow in a same direction as each other from the first (inlet) end to the second (outlet) end. The third row of footprint areas overlies the fifth and sixth channels, which have opposite fluid flow directions to each other. The fourth row of footprint areas overlies the seventh and eighth channels which have parallel fluid flows in the same direction from the inlet end to the outlet end. The fifth row of footprint areas overlies the ninth and tenth channels which have fluid flow in opposite directions. The sixth row of footprint areas overlies the eleventh and twelfth channels which have fluid flow direction is opposite to each other. The seventh row of footprint areas overlies the thirteenth and fourteenth channels, each of which have a flow in the same direction as each other from the inlet end to the outlet end of the heat exchanger. In the seventh heat exchanger, each channel is bordered on at least one side by an adjacent channel which has an opposite fluid flow direction, with the exception of the one outermost peripheral channel on one side of the core (the fourteenth channel) which is bounded by an adjacent (thirteenth) channel which has a same fluid flow direction.

[0279] Referring to Figure 84 herein, there is shown in view from one end a heat exchanger core 8400 of an eighth heat exchanger. The eighth heat exchanger core has eighteen channels running in parallel across the width of the core, the channels being formed between first side wall 8401 , second side wall 8402, and a plurality of connecting walls 8403 extending between the first and second side walls. As described herein before with reference to other embodiments each channel has an internal surface comprising a portion of an inner wall of the first sidewall, a portion of an inner wall of the second side wall, a surface of a first connecting wall and a surface of a second connecting wall, wherein the first and second connecting walls lie on each side of said channel.

[0280] Referring to Figure 85 herein, there is illustrated schematically a section plane H - H which bisects the core of the eighth heat exchanger, said plane being parallel to an outer surface of the first sidewall 8401 and parallel to an outer surface of the second side wall 8402 and lying midway therebetween.

[0281] Referring to Figure 86 herein, there is illustrated schematically in cut away view along the plane H - H the core of the eighth heat exchanger showing heat exchange fluid flow direction through each of the channels. Across the width of the core, the plurality of channels are arranged into six sets of three channels each, wherein each set of three channels comprises an“S” flow path, having two channels which convey heat exchange fluid in a first direction between the first (inlet) end of the heat exchanger and a second (outlet) end of the heat exchanger and a single channel which returns heat exchange fluid from the second end back to the first end, creating a contra-flow arrangement.

[0282] Numbering the channels 1 - 18 from top to bottom in figure 86, fluid flows from the first end to the second end through channels 1 , 3, 4, 6, 7, 9, 10, 12, 13, 15, 16, and 18. Fluid flows in the opposite direction from the second end to the first end through channels 2, 5, 8, 1 1 , 14, and 17. [0283] Referring to Figure 87 herein, there is shown the core of the eighth heat exchanger in cut away view along the plane H - H, showing also the footprint areas corresponding to the anode ends of a plurality of individual battery cells arranged in six layers or rows in a log pile arrangement in which a main central length axis of each battery cell lies at the centre of a hexagon surrounded by up to six other battery cells.

[0284] On the outer surface of a side wall of the heat exchanger core, there are a plurality of substantially circular footprint areas which are in direct thermal contact with the ends of the battery cells as shown. Each footprint area overlies three channels and two connecting walls between the side walls of the heat exchanger core. Heat is transferred between a corresponding footprint area which encompasses the inner wall surfaces of each of three underlying channels, conducts through the material of the sidewall to the outer surface of the sidewall, and then in thermal contact with the ends of the battery cell. Heat is conducted between the end of each battery cell through the sidewall to each of three underlying fluid flows via the sidewall and via two connecting walls which coincide with the footprint area of the end of the battery cell.

[0285] Referring to Figure 88 herein, there is illustrated schematically a temperature map of the outer heat exchange surface of a heat exchanger core substantially as described herein before, for a ten channel heat exchanger, in which all channels extend between first and second ends of the heat exchanger core and in which heat exchange fluid enters the core at a first end, shown on the left -hand side in Figure 88 and exits the heat exchanger core at a second end, shown on the right - hand side in Figure 88. Heat exchange fluid flows in a straight through flow path in parallel along all channels, from the first end to the second end, in a flow direction and without any heat exchange fluid contraflow in the opposite direction. This is prior art.

[0286] The end surface of each battery cell has a thermal“footprint” on the outer surface of the heat exchanger core. The temperature of the thermal footprint is shown in Figure 88 herein, when the lithium ion battery cells are under high load, either charging or discharging rapidly at their highest rate.

[0287] The lighter shaded circles represent relatively lower temperatures at the end of individual circular cylindrical battery cells, and the darker shaded circles represent relatively higher temperatures. As shown in Figure 88, battery cells whose ends have locations adjacent the outer surface of the heat exchanger core nearer to the inlet end (first end) have a relatively lower temperature than the ends of battery cells which are furthest away from the heat exchange fluid inlet, at the second outlet end, with there being a progressive increase in temperature of the ends of the batteries adjacent the heat exchange surface of the core travelling from the first end to the second, the fluid becomes progressively warmer as it travels along the length of the heat exchanger core, so that for battery cells who have their end surfaces at the second heat exchanger core, the heat exchange fluid is relatively warmer and therefore absorbs less heat energy from those battery cells at the second end of the heat exchange core compared to the battery cells at the first and heat exchange core where the incoming heat exchange fluid is relatively cooler.

[0288] Referring to Figure 89 herein, there is illustrated schematically temperature plot for the temperature on the outer surface of the heat exchanger core immediately adjacent corresponding respective lithium ion battery cell ends for a heat exchanger core which is identical to that shown in Figure 88 herein, but in which the flow pattern of heat exchange fluid is arranged in a reciprocating“S” path in which the heat exchange fluid enters the heat exchanger at a first end as shown on the left- hand side of Figure 89, passes through a first set of channels from the first end to the second end, in a first pass of the core in the flow direction; is returned at the second end of the heat exchanger core to traverse from the second to the first end in a first return pass along a second set of channels; and is returned at the first end to flow in a third set of channels from the first entered the second end in a third pass of the heat exchanger core. The end surface of each battery cell has a thermal“footprint” on the outer surface of the heat exchanger core. The temperature of the thermal footprint is shown in figure 89 herein, when the battery cells are under high load, either charging or discharging rapidly at their highest rate.

[0289] As shown in Figure 89, the density of shading represents temperature at areas of the outer surface of the heat exchanger core immediately adjacent corresponding respective end surfaces of a plurality of battery cells, where a lighter shading represents a lower temperature and a darker shading represents a relatively higher temperature.

[0290] Referring to Figure 90 herein, there is illustrated schematically a temperature shading key for comparison of temperatures in Figures 88 and 89, in which a relatively lighter shading represents a relatively lower temperature and in which are relatively darker shading represents a relatively higher temperature. The temperature key of Figure 90 applies to both Figure 88 and 89, so as to enable direct comparison of temperatures for the different heat exchange fluid flow patterns of Figures 88 and 89 and to allow a direct comparison between a simple end-to-end flow and an“S” pattern contraflow arrangement. The temperature key of Figure 90 shows temperature on a linear scale of degrees centigrade from left to right.

[0291] Comparing the temperature distribution in Figure 88 with that of Figure

89, in Figure 90 the minimum temperature and maximum temperature in the“straight through” end-to-end single pass flow path of Figure 88 is shown as temperatures A in Figure 90, whereas the minimum temperature and maximum temperature experienced in the“S” flow path of Figure 89 is shown as temperatures B in Figure

90. Figures 88 and 89 give a direct comparison of temperatures in the same battery pack, and the same heat exchanger core, all other things being equal, apart from the flow path pattern, and the appropriate end housings and manifold connections to create the different flow path patterns.

[0292] By adopting an“S” pattern reciprocating flow path in which the heat exchange fluid flows in a first pass from first end to second end, returning the heat exchange fluid in a second pass in a contra - flow direction from second end first and, and then returning heat exchange fluid again in the first direction from first and second end in a third pass, there may be achieved a significant improvement in reducing the difference between the maximum temperature range and the minimum temperature range of the fluid from the first end to the second end in a third pass

[0293] By using the multi - pass flow path shown in Figure 89, an approximately 40% or greater improvement in temperature difference between the minimum temperature and maximum temperature can be achieved compared to the identical heat exchanger core operated in a single pass end to end flow path without any contra flow as shown in Figure 88 herein. The temperature range of the“S” flow path heat exchanger shown in figure 89 is approximately 60% or lower than the temperature range of the same heat exchanger core when operated with all channels in a straight through end-to-end flow path.

[0294] The same level of temperature range reduction can be obtained with a U path.

Dimensions of heat exchanger core

[0295] In the best mode embodiments, the heat exchanger cores may have dimensions as follows:

• Overall length of heat exchanger core, excluding manifolds and coolant inlet and outlet tubes - in the range 50 mm to 3,000mm, and preferably in the range 300mm to 2,000mm.

• Overall width of heat exchanger core in a direction transverse to the main overall length direction - in the range 10mm to 500mm and preferably in the range 40mm to 300mm.

• Overall thickness of heat exchanger core in a direction which is perpendicular to the length and perpendicular to the width - in the range 2mm to 20mm, and preferably in the range 4mm to 6mm

Heat exchange fluid

[0296] In the best mode embodiments described herein, the heat exchange fluid preferably comprises a liquid coolant, which is capable of withstanding the full range of temperature variations which a battery module may experience in any climate of any country in which the module is to be sold, which typically ranges from - 51 °C to + 60°C, so that the battery module can operate in almost all location in the world. In the best mode, the battery coolant may comprise ethylene glycol or an ethylene glycol-water mixture, but in the general case any liquid coolant which avoids freezing and boiling within the required operating range may be used.

[0297] In the embodiments described, the heat exchanger may operate with a forced fluid system in which the heat exchange fluid flow is pressurized. Using liquid coolant as the heat exchange fluid, when liquid coolant is pressurized above atmospheric pressure, the boiling point of the liquid coolant generally increases from its boiling point at atmospheric pressure. Typically, the heat exchanger will operate under liquid coolant pressures in the range 0 barg to 3 barg .

[0298] In the specific embodiments disclosed herein, the fluid pressure drop between fluid inlet and fluid outlet is typically in the range 1 mbar to 750 mbar.

Construction, materials and assembly

[0299] The above mentioned embodiments the end housings and heat exchanger core may be made of the same or different materials to each other, including:

• Steel

• Aluminium

• A relatively high thermally conductive plastics material

• A relatively high thermally conductive plastics material, which is also an electrical insulator.

[0300] The end housings and the core may be made of the same material. In other embodiments, the end housings may be made of a different material to that of the core.

[0301] In a hybrid material embodiment, the first and/or second end housings may be formed of a plastics material, and the heat exchanger core may be formed of an aluminium extrusion, or as a steel pressed material. Where the core is formed of aluminium, the core may be extruded or pultruded. In the hybrid embodiment, the end housings may be attached to the core using an epoxy adhesive, optionally with a set of retaining tabs or engaging lugs to retain the end housings to the respective ends of the core. The end housings may be made of individual components each of which are injection moulded.

[0302] In an embodiment formed fully of a high thermal conductivity plastics material, the end housings and the central heat exchanger core may be made of said plastics material. The end housings may be formed of injection moulded components. The end housings may be attached to the central core by an epoxy adhesive and/or using a set of engagement members to ensure that the central core remains attached to the end housings in a leak-proof manner at all temperatures within the design temperature range specification of the heat exchanger. The central core may be formed by injection moulding, extrusion or pultrusion.

[0303] In a further embodiment formed fully of high thermal conductivity plastics material, the heat exchanger may be constructed as two shell halves, each of which is formed by injection moulding, a connection surface between the two shell halves being located between the first and second side walls of the heat exchanger core, bisecting each of the channels of the core, and bisecting each end housing.

[0304] A first shell half may comprise one side of the first end housing, one side of the heat exchanger core, and one side of the second end housing. A second shell half may comprise another side of the first end housing, another side of the heat exchanger core, and another side of the second end housing. Internal partition members may be formed separately for each end and the whole heat exchanger may be held together and sealed using epoxy adhesive or welding. The shell halves and partition members may each be formed by injection moulding.

[0305] In various embodiments, the ends of the heat exchanger core may be machined so that the core has a substantially same cross-sectional profile in a plane perpendicular to the main length axis of the core for regions where the core lies adjacent a plurality of individual battery cells, but one or more ends of the core have a different cross-sectional profile due to machining of the end regions where the end regions connect with the end housings.

[0306] In yet a further embodiment in which the outer shells of the end housings and the core are all formed from a same material, each shell half may be formed as in the all plastics version described above comprising two half shells and additional partition members, except that the shell halves may be cast or pressed instead of injection moulded. This may be suitable where the material of the core and external shell of the one or more end housings are aluminium or other metal material suitable for casting and which can be attached together in a fluid tight and reliable manner using an adhesive, braze or solder.

[0307] In a variation of each of the embodiment heat exchangers as disclosed herein, the assembly of the first and second manifolds to the heat exchanger core may comprise a set of indents on the outer surface of the ends of the heat exchanger core, with a corresponding set of protrusions on the inner surface of the portion of the manifold which slides over the end of the heat exchanger core, with a shaped gasket or seal between the end wall of the heat exchanger core and the partition walls of the manifold creating a fluid tight seal between the end wall of the heat exchange core and the partition walls of the manifold so that the heat exchanger can be assembled by a clip - together construction with the manifolds clipping over the entrance of the heat exchanger core, in addition to any adhesive between the inner faces of the end manifolds and the outer surfaces of the heat exchanger core.

[0308] In use in a battery installation of an electric vehicle, typically a plurality of battery packs as described above may be arranged in an array on a floor pan of the vehicle, with a plurality of fluid tubes of an external heat exchange circuit lying between or above the array of battery cells, and with other components of the external heat exchanger including one or more fluid pumps, the control system, and the one or more air cooled heat exchangers (radiators).

[0309] In other embodiment the battery pack or packs may be provided for stationary power. For example as used in a domestic, retail or commercial battery power pack.

[0310] In the above described embodiments herein, the individual technical features of each of the embodiments described may be substituted and/or interchanged with the individual technical features of each other embodiment in any combination and/ or permutation, to create new variations of the above embodiments having new combinations and /or permutations of individual technical features selected from amongst the totality of technical features disclosed in the above individual embodiments.

Claims

1. A heat exchanger for regulating the temperature of a battery pack, said heat exchanger comprising:

a heat exchanger core said core comprising:

a first side wall

a second side wall

a first end

a second end

a plurality of connecting walls each extending between said first and second side walls, said connecting walls and said first and second side walls defining a plurality of elongate channels each extending between said first and second ends of said heat exchanger; and

an end housing comprising:

a first end housing side wall;

a second end housing side wall; and

2. The heat exchanger as claimed in claim 1 , wherein each first channel of said first set of channels is separated from a said second channel of said second set of channels by a said connecting wall, such that heat may transfer through said connecting wall between fluid flowing in said first channel in said first direction, and fluid flowing in said second channel in said second direction.

3. The heat exchanger as claimed in claim 1 or 2, having a maximum temperature range between a hottest temperature on a said outer heat exchange surface and a lowest temperature on said outer heat exchange surface which is 60% or less than a maximum temperature range of a corresponding hottest temperature on said outer heat exchange surface and a corresponding lowest temperature of said outer heat exchange surface where said same heat exchanger core is connected for a single pass end to end flow of said fluid in a single direction across said heat exchanger core.

4. The heat exchanger as claimed in any one of the preceding claims, wherein:

said first side wall comprises an end face;

said second side wall comprises an end face;

wherein said end faces of said internal wall of said end housing face opposite to said end faces of said first side wall, said second side wall and said plurality of connecting walls of the main heat exchange core.

5. The heat exchanger as claimed in any one of the preceding claims, wherein said heat exchanger core comprises an extruded component which has a same cross-sectional profile in a plane perpendicular to a main length direction, at all positions along a whole length of said heat exchanger core in the area that the battery cells contact.

6. The heat exchanger as claimed in any one of the preceding claims, wherein one end of said end housing fits over and around an outside of an end of said heat exchanger core.

7. The heat exchanger as claimed in any one of the preceding claims, comprising wherein said plurality of connecting walls and said side walls define a plurality of apertures, each said aperture communicating with a chamber within said end housing .

8. The heat exchanger as claimed in any one of preceding claims, wherein said heat exchanger core is formed of a metal and said end housings are formed of a plastics material.

9. The heat exchanger as claimed in any one of claims 1 to 7, wherein said heat exchanger core and said end housings are each formed of a plastics material.

10. The heat exchanger as claimed in any one of the preceding claims, wherein a said end housing is attached to a said end of said heat exchanger core by an epoxy adhesive.

11. A heat exchanger for regulating the temperature of a battery of electrical energy cells, said heat exchanger comprising:

a heat exchange core;

a first end housing having a fluid inlet tube; and

a second end housing having a fluid outlet tube;

said heat exchange core comprising a first side wall, a second side wall, and a plurality of channels positioned between said first and second side walls,

said heat exchange core having a first end and a second end;

said first end housing being arranged to connect said fluid inlet tube with said first plurality of channels to distribute fluid into said first plurality of channels; and

said second end housing being arranged to connect said third plurality of channels with said fluid outlet tube to transfer fluid from said third plurality of channels to said fluid outlet tube;

said second end housing and first end housing being arranged to connect said second plurality of channels wherein a fluid flow direction in said first plurality of channels is opposite to a flow direction in said second plurality of channels;

an outer surface of said first side wall of said heat exchange core comprises a plurality of projected outer partition areas, each said projected outer partition area corresponding to an end area of one end of a said electrical energy cell; and

an inner surface of said first side wall is partitioned into a plurality of inner partition areas;

each said inner partition area lying on an opposite side of a same said side wall as and coinciding with a corresponding respective said outer partition area,

wherein each said inner partition area comprises an inner wall of at least two channel types, of said first channel or said second channel.

12. The heat exchanger as claimed in claim 11 , wherein said first end housing comprises:

a first outer shell component;

a second outer shell component;

said partition member comprising a first plurality of wall formations for directing fluid between said first cavity and said first plurality of channels; and

said partition member comprising a second plurality of wall formations for directing fluid between said second plurality of channels and said second cavity.

13. The heat exchanger as claimed in claim 11 or 12, wherein said first plurality of wall formations are arranged to seal across a plurality of dividing walls extending between said first sidewall and said second sidewall of said heat exchanger core.

14. The heat exchanger as claimed in any one of claims 11 to 13, wherein said first end housing and said second end housing are formed by said first outer shell component, said second outer shell component and said partition member.

15. A heat exchanger for regulating the temperature of a battery of electrical energy cells, said heat exchanger comprising:

a first end housing comprising:

a first manifold for the inlet of a flow of heat exchange fluid, said first manifold including a heat exchange fluid inlet;

a second manifold for the outlet of a flow of heat exchange fluid, said second manifold including a heat exchange fluid outlet;

a second end housing;

a heat exchange core comprising:

a first sidewall and a second side wall;

a plurality of first fluid channels each extending between said first end housing and said second end housing, said first fluid channels for carrying heat exchange fluid in a first direction; and

a plurality of second fluid channels each extending between said second end housing and said first end housing, said second fluid channels for carrying heat exchange fluid in a second direction, wherein said second direction is opposite to said first direction;

a plurality of connecting walls each extending between said first side wall and said second side wall, said plurality of connecting walls partitioning a space between said first and second sidewalls into a said plurality of first channels and said plurality of second channels such that as viewed in a direction perpendicular to a main plane of a said first and/or second said side walls, said first and second channels are arranged side-by-side with respect to each other;

said first manifold comprising a plurality of passageways for distributing a flow of heat exchange fluid between said heat exchange inlet and said plurality of first fluid channels; and said second manifold comprising a plurality of passageways for distributing said flow of heat exchange fluid between said plurality of second fluid channels and said outlet.

16. The heat exchanger as claimed in claim 15, wherein said first manifold comprises:

a first outer shell defining a first cavity;

said inner wall comprising a plurality of first apertures defining said plurality of first channels and a plurality of second apertures defining said plurality of said second channels.

17. The heat exchanger as claimed in claim 16, wherein said first outer shell and said second outer shell are substantially identical to each other.

18. The heat exchanger as claimed in claim 16 or 17, wherein said inner wall component comprises a separate component to said first or second outer shell.

19. The heat exchanger as claimed in any one of claims 16 to 18, wherein said heat exchange core comprises:

a first side wall plate;

a second side wall plate;

said first side wall plate being spaced apart from and lying opposite from said second side wall plate; said plurality of connecting walls each extending between said first side wall plate and said second side wall plate, said plurality of connecting walls partitioning a space between said first and second sidewalls into said plurality of channels such that as viewed in a direction perpendicular to a main plane of a said first and/or second said side wall, said channels are arranged side-by-side with respect to each other.

20. The heat exchanger as claimed in any one of claims 16 to 19, wherein said heat exchanger core is formed as an extrusion.

21. A heat exchanger for regulating the temperature of a plurality of electrical energy cells, said heat exchanger comprising:

an outer surface of said first side wall of said heat exchange core comprises a plurality of outer areas, each said outer area corresponding to an end area of one end of a said electrical energy cell; and

an inner surface of said first side wall comprises a plurality of inner areas;

each said inner area lying on an opposite side of a same said side wall as and coinciding with a corresponding respective said outer area as viewed in a direction perpendicular to a main outer face of said side wall;

wherein each said inner area comprises an inner wall of at least one said first channel and an inner wall of at least one said second channel; and each said first flow channel lies immediately next to a said second flow channel, and is separated therefrom by a corresponding connecting wall extending between said first and second side walls.

22. The heat exchanger as claimed in claim 21 , wherein each said end area corresponds with the area occupied by an anode of a said electrical energy cell.

23. A battery apparatus comprising a battery pack and a heat exchanger; said battery pack comprising a first plurality of battery cells arranged in at least one row;

each said battery cell having a body, said body having first and second ends; each of said first ends lying on a first end plane, and each of said second ends lying on a second end plane such that a said first and/ or second end plane lies across a main length direction of each said battery cell;

said heat exchanger comprising:

a first end and a second end;

a plurality of first fluid channels each extending between said first and second ends, said first fluid channels carrying heat exchange fluid in a first direction from said first end to said second end;

a plurality of second fluid channels each extending between said first and second ends, said second fluid channels carrying heat exchange fluid in a second direction, wherein said second direction is opposite to said first direction;

each said first channel lies immediately next to a said second channel and is separated therefrom by a corresponding wall;

an outer heat exchange surface which lies substantially on a first plane;

wherein each said battery cell describes an area footprint projecting from a perimeter area of said end of said battery cell in a direction towards said heat exchanger, and which projects on to said outer heat exchange surface; wherein each said area footprint projects in a direction perpendicular to said first plane through at least one said first fluid channel and through at least one said second fluid channel.

24. A manifold for a heat exchanger comprising:

a first outer shell component;

a second outer shell component;

said second plurality of wall formations forming a second plurality of channels for directing fluid between said second cavity and said second plurality of apertures; wherein each said first channel lies immediately adjacent to at least one said second channel.

25. A heat exchanger as claimed in claim 1 with a heat exchanger core comprising:

a first side wall;

a second side wall;

said core having a first end and a second end; said first side wall, said second side wall, and each of said plurality of connecting walls extending fully between said first and second ends, such that each of said plurality of channels are open at said first end and are open at said second end.

26. The heat exchanger core as claimed in claim 25, wherein:

said first side wall comprises a first end face at said first end of said core;

said first side wall comprises a second end face at said second end of said core;

said second said wall comprises a first end face at said first end of said core; said second side wall comprises a second end face at said second end of said core;

each said connecting wall comprises a corresponding respective second end face and said second end of said core;

wherein each of said end faces lie on a plane which is perpendicular to a main plane which bisects each of said plurality of elongate channels.

27. The heat exchanger core as claimed in claim 25 or 26, wherein said plurality of channels are arranged in parallel in a single layer across a main width of said heat exchanger core;

28. The heat exchanger core as claimed in any one of claims 25 to 28, wherein at least one said connecting wall comprises one or a plurality of fins structures having a base portion attached to said at least one connecting wall, and a tip portion which extends into a cavity of a said elongate channel.

29. The heat exchanger as claimed in any one of the preceding claims, wherein said heat exchanger core comprises an extruded component which has a same cross-sectional profile in a plane perpendicular to a main length direction, at all positions along a whole length of said heat exchanger core.

30. A heat exchanger as claimed in any one of claims 1 to 29, wherein a said end housing and/ or a said heat exchanger core is formed of a high thermal conductivity plastics material.