GB2553537A

GB2553537A - Battery box

Info

Publication number: GB2553537A
Application number: GB1615190.4A
Authority: GB
Inventors: Simonavicius Matas; Jardine Ben
Original assignee: Arrival Ltd
Current assignee: Arrival UK Ltd
Priority date: 2016-09-07
Filing date: 2016-09-07
Publication date: 2018-03-14
Anticipated expiration: 2036-09-07
Also published as: GB2553537B; GB201615190D0

Abstract

A battery box 25 for a battery pack of an electric vehicle includes a base 34, side walls 35 and a lid 27. At least one of the base, side walls and lid includes a composite panel comprising a core with cavities and skins bonded to opposite sides of the core. The core may be a honeycomb structure (29 fig.3) with the skins (31 fig.3) being glass fibre reinforced sheets. A floor panel 36 with inlet vent 39 may be provided under the base with vent holes 38 and an outlet vent 40 in a side wall. An airtight seal may be formed between the base and side panels, which may be integrally formed, and a seal may be used between the walls and the lid. RFI shielding 33 may be included in/on the box in the form of embedded wires or conductive paint with panels being electrically bonded in order to provide electromagnetic compatibility.

Description

(71) Applicant(s):

Arrival Limited

Unit 2, Southam Road, Banbury, Oxfordshire, OX16 2DJ, United Kingdom (72) Inventor(s):

Matas Simonavicius Ben Jardine (74) Agent and/or Address for Service:

Venner Shipley LLP

200 Aldersgate, LONDON, EC1A4HD,

United Kingdom (51) INT CL:

B60K 1/04 (2006.01) BOOL 11/18 (2006.01)

H01M 2/10 (2006.01) (56) Documents Cited:

CN 103730616 A DE 102013015837 A1

FR 002986374 A1 (58) Field of Search:

INT CL B32B, B60K, B60L, H01M Other: WPI, EPODOC, TXTA.

(54) Title of the Invention: Battery box

Abstract Title: A battery box of composite sandwich construction with EMI shielding for an electric vehicle (57) A battery box 25 for a battery pack of an electric vehicle includes a base 34, side walls 35 and a lid 27. At least one of the base, side walls and lid includes a composite panel comprising a core with cavities and skins bonded to opposite sides of the core. The core may be a honeycomb structure (29 fig.3) with the skins (31 fig.3) being glass fibre reinforced sheets. A floor panel 36 with inlet vent 39 may be provided under the base with vent holes 38 and an outlet vent 40 in a side wall. An airtight seal may be formed between the base and side panels, which may be integrally formed, and a seal may be used between the walls and the lid. RFI shielding 33 may be included in/on the box in the form of embedded wires or conductive paint with panels being electrically bonded in order to provide electromagnetic compatibility.

FIG. 2

33b

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4/8

5/8

7/8

8/8

14/15

•siBattery Box

Technical Field

The present invention relates to a battery box and, in particular, to a box for containing 5 a plurality of battery modules as a battery pack for use in an electric vehicle.

Background

The drive for more fuel efficient and environmentally friendly transport solutions is seeing an increasing level of development in the field of electric vehicles. Such vehicles include not only passenger vehicles for personal transport, but also commercial vehicles such as buses and trucks. Such electric vehicles (EVs) include pure battery electric vehicles (BEVs) powered by batteries alone, and range extender electric vehicles (REEVs) which also include a small internal combustion engine (ICE) to generate electricity to supplement the battery power source. All such EVs include battery packs for supplying electrical power to the electric drive motor(s). Such battery packs typically comprise a number of connected battery modules contained within a battery box, conventionally a metallic battery box, for example made of steel or aluminium.

In passenger car EVs, the battery packs are contained within the body of the vehicle and so are generally not exposed to ambient conditions such as temperature fluctuations, rain, dirt and dust or impact from debris thrown up from the road. However, in commercial vehicles, such as delivery trucks, the battery packs may be mounted to the vehicle chassis rails and so may be at least partially exposed to such environmental factors in vehicle use.

Summary

In accordance with embodiments of the invention, there is provided a battery box for a battery pack of an electric vehicle comprising a box portion comprising a base and a plurality of side walls defining an interior space and an upper opening, a lid secured over the upper opening to close the box portion, wherein at least one of the base wall, side walls and lid comprises a composite panel comprising a core having a plurality of cavities therein and first and second skins respectively bonded to first and second opposite sides of the core.

All of the base, side walls and lid may comprise the composite panels. The core may comprise a honeycomb structure. The honeycomb core maybe made of polypropylene and the skins may comprise glass fibre reinforced polypropylene sheets.

At least two out of the base and side walls may be integrally formed from a single composite panel.

The battery box may further comprise a floor panel parallel to and spaced from the base panel to define a passage between the floor panel and the base panel.

The floor panel may include a plurality of apertures extending therethrough to fluidly communicate the passage with the remaining interior space of the box portion.

A side wall of the box portion may include an outlet vent aperture extending therethrough proximate an upper portion thereof, and an inlet vent aperture extending therethrough proximate a lower portion thereof.

The inlet vent may communicate with the passage between the floor panel and the base panel, and the outlet vent communicates with the remaining interior space of the box portion.

The area of the outlet vent aperture maybe substantially the same as the area of the inlet vent aperture.

The side walls panels, base panel and lid of the battery box may include an EMC shielding. The EMC shielding may comprise a lining of woven fabric of metallic fibres, and/or may comprise a coating of conductive metallic paint. The EMC shielding may comprise a lining on the inside surfaces of the side wall panels, base panel and lid. The EMC shielding may comprise a layer of material embedded within at least one of the side wall panels, base panel and lid. The EMC shielding may be provided between the core and at least one of the skins of the composite panel(s), or may be embedded within the core, or embedded within one of the skins. The EMC shielding provided on the lid maybe electrically conductively connected to the EMC shielding provided on the side wall panels and the base.

-3A conductive connecting element maybe connected to the lid and a side wall panel to electrically conductively connect the EMC shielding provided on the lid and side wall panels and the base.

An airtight seal may be formed at the junction where each side panel, base panel and the lid abut.

The battery box may comprise a sealing element disposed between the box portion and the lid to form an air-tight seal between the box portion and the lid.

A closure element may extend from the lid to the box portion to secure the lid to the box portion. The closure element may be formed integrally with the lid. The closure element may extend around substantially the entire perimeter of the lid and box portion. The closure element may depend from a perimeter edge of the lid.

The present invention also provides a method of manufacturing a battery box for a battery pack of an electric vehicle comprising forming a box portion comprising a base and a plurality of side walls defining an interior space and an upper opening, and a lid for securing over the upper opening to close the box portion, at least one of the base wall, side walls and lid comprising a composite panel comprising a core having a plurality of cavities therein and first and second skins respectively bonded to first and second opposite sides of the core.

The method may comprise forming all of the base, side walls and lid from the composite panels.

The method may comprise forming at least two out of the base and side walls are integrally from a single composite panel.

The method may further providing a floor panel parallel to and spaced from the base panel to define a passage between the floor panel and the base panel.

The method may comprise providing a plurality of apertures extending through the floor panel to fluidly communicate the passage with the remaining interior space of the box portion.

-4The method may comprise providing an outlet vent aperture extending through a side wall of the box portion proximate an upper portion thereof, and an inlet vent aperture extending through the side wall of the box portion proximate a lower portion thereof.

The method may comprise providing the inlet vent communicating with the passage between the floor panel and the base panel, and the outlet vent communicating with the remaining interior space of the box portion.

The method may comprise forming the area of the outlet vent aperture as substantially 10 the same as the area of the inlet vent aperture.

The method may comprise providing an EMC shielding on the inside surfaces of the side walls panels, base panel and lid. The EMC shielding may comprise of a lining of woven fabric of metallic fibres, and/or a coating of conductive metallic paint.

The method may comprise providing the EMC shielding on the lid being in electrical conductive connection with the EMC shielding provided on the side wall panels and the base.

The method may comprise providing a conductive connecting element connected to the lid and a side wall panel to electrically conductively connect the EMC shielding provided on the lid and side wall panels and the base.

The method may comprise forming an airtight seal at the junction where each side panel, base panel and the lid abut.

The method may comprise providing a sealing element disposed between the box portion and the lid to form an air-tight seal between the box portion and the lid.

The method may comprise providing a closure element extending from the lid to the box portion to secure the lid to the box portion, and may comprise forming the closure element integrally with the lid.

Brief Description of the Drawings

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

-5Fig. l shows a schematic view of a chassis and drive train of a commercial electric vehicle including a battery box of an embodiment of the invention;

Fig.2 shows a perspective view of a battery box of an embodiment of the invention with a lid shown detached and spaced from the box body;

Fig. 3 shows an exploded perspective view of a composite panel comprising the walls of the battery box of Fig. 2;

Fig. 4 shows a cross-sectional view of the battery box of Fig. 2 taken along the line X-X shown in Fig. 2, but with the lid secured to the box body;

io Fig. 5 shows a cross-sectional view of an edge portion another exemplary battery box of an embodiment of the invention;

Fig. 6 shows a cross-sectional view of an edge portion yet another exemplary battery box of an embodiment of the invention;

Fig. 7 shows a perspective view of a battery pack including the battery box of Fig. 2;

Fig. 8 shows a cross-sectional view of the battery pack of Fig. 7 taken along the line Y-Y shown in Fig. 7, but with the lid secured to the box body; and Fig. 9 shows a schematic system diagram of the battery pack of Figs. 7 and 8.

Detailed Description

Fig. 1 shows a chassis 10 of an exemplary commercial REEV, and comprises a pair of chassis rails 11 to which are mounted a front drivetrain module 12, a rear drivetrain module 13, first and second high voltage battery packs 14,15 and a range extender unit

16.

The front drivetrain module 12 comprises an electric motor 17 and a gearbox 18 which drive front wheels 19 mounted on suspension arms 20. Similarly, the rear drivetrain module 13 comprises an electric motor and a gearbox (not shown - although these are advantageously the same components and configuration as those of the front drivetrain module) which drive rear wheels 23 mounted on suspension arms 24.

The first high voltage battery pack 14 is mounted between the chassis rails 11 and the second high voltage battery pack 15 is mounted on a side of the chassis 10 on an outside of a right chassis rail 11. The range extender unit 16 is mounted on an opposite side of the chassis 10 to the second battery pack 15, on an outside of a left chassis rail 11.

-6Fig 2 shows a battery box 25 of the high voltage battery packs 14,15 and comprises a box body 26 and a box lid 27. The battery box 25 is constructed of a plurality of composite sandwich panels 28, shown in more detail in Fig. 3. Each panel 28 comprises a core 29 formed as a honeycomb structure defining a plurality of cavities

30. Skins 31 are bonded to the major surface on either side of the core 29. The core 29 is formed of polypropylene. The skins 31 are formed of fibreglass fibres embedded in polypropylene.

The lid 27 is secured to the body 26 by mechanical fasteners (not shown), such as 10 threaded bolts, which may be received in threaded inserts (not shown) embedded within the respective box panel 28. In the exemplary embodiment shown, a sealing element 32 is advantageously provided between the box body 26 and the lid 27 to make a seal between the body 26 and the lid 27 when the lid 27 is secured to the body 26. The sealing element 32 may comprise a gasket and may be made of any suitable material, such as a compressible material such as rubber.

A portion of the battery box 25 is advantageously provided with an EMC protective shielding 33. This may be provided as an EMC protective lining and may be provided on an inner surface of the battery box 25. In the exemplary embodiment shown, this comprises a woven fabric sheet of metallic fibres, such as fine steel fibres. However, other forms of EMC lining maybe provided within the scope of the invention, such as a coating of conductive paint, or a plasma zinc coating inner surface of the battery box.

In use, the EMC protective lining serves to shield any electromagnetic fields generated by battery modules within the battery box to stop them affecting any other electronic components in the rest of the vehicle. Both the box body 26 and lid 27 comprise such EMC protective lining 33, which may be provided on their inner surfaces. In order for the EMC protective lining 33 to be optimally effective, and to optimally act as a faraday cage, an EMC protective lining 33a on the box body 26 is electrically conductively connected to an EMC protective lining 33b provided on the inner surface of the lid 27.

It can be seen from the cross-sectional view of Fig. 4 that the box body 26 comprises a base panel 34 and side wall panels 35. It can also be seen that the box body 26 includes a floor panel 36 parallel to and spaced from the base panel 34 which defines a passage 37 between the base panel 34 and the floor panel 36. The floor panel 36 includes a plurality of vent holes 38 communicating the passage 37 with the remaining interior space of the box body 26. The floor panel 36 is preferably made of the same sandwich

-Ίpanel 28 material as the base panel 34 and side wall panels 35 described above with reference to Fig. 3.

One side wall panel 35 includes an inlet aperture 39 near the bottom edge which 5 communicates with the passage 37, and an outlet aperture 40 towards the top edge.

Vent holes 38 and the inlet and outlet apertures 39,40 are to enable air circulation within the battery box 25 as will be described hereafter. The inlet and outlet apertures 39, 40 may be the same shape or different shapes (as shown in Fig. 2) within the scope of the invention. Advantageously, both the inlet and outlet apertures 39,40 are of substantially the same area, that is the same “surface” area, occupying the substantially the same area of the respective side wall panel 35 in which they are provided. This is to help towards preventing an imbalance or undesirable restrictions in air flow out of and into the battery box, as will be described hereafter.

An advantage of constructing the battery box 25 of an embodiment of the invention of composite panels 28 comprising a polypropylene core 29 with polypropylene fibre reinforced skins 31, as described above, is that the panels 28 maybe easily shaped during manufacture. This can be done by heating the panel 28 to soften the polypropylene and then the panel 28 can be bent to the desired angle and held in position until the panel 28 cools and the polypropylene hardens again. As such, a plurality of the side wall panels 35 and/or the base panel 34 may be formed as a single composite panel 28. For example, all side wall panels 35 may be made from one single composite panel 28 with a separate composite panel 28 for the base panel 34 bonded to the bottom edge of the side wall panels 35. Alternatively, two opposite site wall panels

35 and the base panel 34 may be made from one single composite panel 28 with separate composite panels 28 for the two remaining side wall panels 35 bonded to the side edges of the integral base and side wall panel component.

An advantage of forming at least two of the box panels from one integral composite panel is that the number of panel joins is reduced. This helps in ensuring the resulting battery box 25 is effectively sealed from ambient conditions as it reduces the number of joins where the seal between separate panels may leak and compromise the box integrity. Prevention of ingress of moisture and dust into the battery box 25 is advantageous as such ingress can be detrimental to sensitive electrical and electronic components of the battery pack 14,15 (described in more detail below). This is particularly relevant to the use of the battery box in a commercial vehicle in which, as

-8described above, the battery box 25 is on the outside of the vehicle chassis 10 and so is exposed to such environmental conditions. Also, maintaining a substantially contaminant-free environment within the battery box 25 helps in controlling the temperature and humidity within the battery box 25 when part of a battery pack having a thermal control unit (described in more detail below) as it helps towards preventing cooler or hotter ambient air entering the battery box and affecting the internal temperature. It also helps towards preventing moisture in ambient air affecting the humidity within the battery box 25. Such construction also means the number of cutting steps, and separate components used in the box manufacture is reduced, simplifying manufacture and thereby reducing manufacturing cost and time. Such panels, constructed of a polypropylene honeycomb core with fibreglass polypropylene reinforced skins, are also a relatively cost-effective material from which to construct the battery boxes, compared to other known lightweight materials such as carbon fibre for example. Also, carbon fibre is much more difficult to use in manufacture and to shape.

A further advantage of the above-described composite panel battery box 25 construction is that the composite panel 28 material includes a large number of cavities 30 within the core 29 which makes the composite panels good thermal insulators. This further helps in temperature control within the battery box 25 when part of a battery pack as it reduces the impact of ambient temperature affecting the internal battery box 25 temperature. This has yet further importance in colder climates since EV batteries are generally unable to be as effectively charged when below zero degrees Celsius and so a thermally insulating box construction is beneficial in helping avoid excessively low battery temperature.

A further advantage of the above-described composite panel battery box 25 construction is that the composite panel 28 material is of a lighter weight than conventional battery boxes made from, for example, metal such as steel. For example, a battery box of approximate dimensions 1200mm (length) x 600mm (width) x 400mm (height) made from conventional grade sheet steel would weigh around 70 kg, whereas an equivalent size battery box of an embodiment of the invention made of composite panels 28 as described above, would weigh around 15 kg, a weight difference of almost 80%. The composite panel 28 weighs around 5kg per square metre. Weight reduction is a key factor in increasing fuel economy of vehicles and is particularly important in the context of EVs to maximise vehicle efficiency and vehicle range on a given battery charge, and in reducing the battery power needed to propel the vehicle.

-9A yet further advantage of the above-described composite panel battery box 25 construction is that the composite panel 28 material is easy to repair if physical damage is sustained in use. This is beneficial since, as mentioned above, in use in a commercial vehicle, the battery box 25 is often mounted on the outside of the vehicle chassis 10 and so is exposed to debris which may be thrown up from the road. Damage to the skins 31 can be repaired by filling using a polypropylene gun, or if a section of the composite panel 28 needs replacing, a section can be cut out and a replacement section cut to size and bonded in place using a polypropylene gun or other suitable bonding agent.

Fig. 5 shows a cross-section through a portion of another exemplary battery box 25 of an embodiment of the invention, showing another exemplary means of securing the lid 27 to the box body 26. Like features with the battery box shown in Figs. 2 and 4 retain the same reference numerals. In the embodiment shown in Fig. 5, the sealing element

32 is provided around the top edge of the side wall panel 35 and the lid 27. A closure element in the form of an angle bracket 49 is secured around the join between the edge of the lid 27 and the upper edge of the side wall panel 35 to secure the lid 27 to the box body 26. Mechanical fasteners (not shown) may secure the angle bracket 49 in place to the box body 26 and/or lid 27. In order to ensure an electrical connection between the

EMC protective lining 33a of the box body 26 and the EMC protective lining 33b provided on the lid 27 (particularly in the exemplary embodiment shown in which a sealing element 32 is disposed between the box body 26 and lid 27 which may be electrically insulating), at least one electrically conductive connecting strip 50 may be provided extending between the inner surface of the box body 26 and the inner surface of the lid 27. The connecting strip 50 may be mechanically connected to the box body 26 and lid 27 by appropriate mechanical fasteners 51. The connecting strip may comprise any suitable conductive material within the scope of the invention.

Fig. 6 shows a cross-section through a portion of yet another exemplary battery box 25 of an embodiment of the invention, showing yet another exemplary means of securing the lid 27 to the box body 26. Like features with the battery box shown in Figs. 2 and 4 retain the same reference numerals. In the alternative configuration of Fig. 6, the EMC protective lining 33a on the side wall panels 35 extends across the top edge of the side wall panels 35. The EMC protective lining 33b on the lid 27 extends sufficiently towards the perimeter edge of the lid 27 so that when the lid 27 is placed on the box body 26, the two EMC protective linings 33a, 33b are in contact and so are electrically

- 10 connected. This contact is also facilitated by the sealing element 32 not being disposed between the box body 26 and lid 27 at the upper edge of the of the side wall panels 35.

The lid 27 includes a closure element in the form of an integral securing skirt 52 5 depending downwards around the edge of the lid 27. The securing skirt 52 may be a polypropylene component bonded, welded or melted using a heat gun, onto the lid panel 27. Thereby, the closure element, in the exemplary body a securing skirt 52, may be integrally formed with the lid 27. The lid 27 is secured to the box body 26 by mechanical fasteners (not shown) extending through the securing skirt 52 into the side wall panels 35. In the exemplary embodiment shown in Fig. 6, a sealing element 32 is provided between the securing skirt 52 and the box body 26/lid 27 over the join between the box body 26 and lid 27. Although advantageous, the sealing element 32 is not an essential element however.

It should be appreciated that the features of the battery boxes 25 shown in Figs. 5 and 6 are interchangeable within the scope of the invention. For example, the angle bracket 49 of Fig. 5 could be omitted and replaced with the securing skirt of Fig. 6, and vice versa. Also, as discussed above, the sealing element 32 maybe omitted. An acceptable level of prevention of dust/contaminant ingress into the battery box 25 maybe achieved by the angle bracket 49/securing skirt 52 being secured to the battery box 25, holding the lid 27 securely in place on the box body 26, and covering the join between the box body 26 and lid 27. It will be appreciated that other configurations of securing elements may be provided within the scope of the invention to secure the lid 27 to the box body 26, in addition or alternatives to the angle bracket 49 and securing skirt 52.

Also, the angle bracket 49 and/or securing skirt may extend around the entire perimeter of the battery box 25, or may be provided at discrete locations around the perimeter of the battery box 25. Extending around the entire perimeter may advantageously provide enhanced contaminant ingress prevention. Being provided at discrete locations may facilitate ease of manufacture and reduce cost of materials and manufacture.

The second high voltage battery pack 15 comprises the exemplary battery box 25 of an embodiment of the invention of Fig. 2, and is shown in Fig. 7, again with the lid 27 detached for illustrative purposes, and in cross-section in Fig. 8. A schematic system diagram of the battery pack 15 is shown in Fig. 9. Within the interior of the box 26 is provided a plurality of battery modules 41, which are spaced from each other to define

- 11 air flow passages 42 between the battery modules 41. Each battery module 41 comprises a plurality of connected cells with appropriate control and balancing electronics (not shown). The battery modules 41 are supported on the floor panel 36, as can be seen more clearly in Fig. 8. The battery modules 41 are positioned on the floor panel 36 such that at least some of the air flow passages 42 between the battery modules 41 align with at least some of the vent holes 38 in the floor panel 36.

A thermal control unit 43 is provided on the side wall panel 35 which includes the inlet and outlet apertures 39, 40. The thermal control unit 43 comprises a housing 44 containing a fan 45 and an air conditioning unit 46. The thermal control unit 43 extends over the inlet and outlet apertures 39,40 and includes an exhaust port 47 aligned with the inlet aperture 39 of the battery box 26 and an intake port 48 aligned with the outlet aperture 40 of the battery box 26. At least one sealing member 53 (see Fig. 8) is advantageously provided between the thermal control unit 43 and the side wall 35 of the battery box 26. A single sealing member 53 may be provided between the thermal control unit 43 and the side wall 35 of the battery box 25. Alternatively, or in addition, a first sealing member 53 may be provided around the exhaust port 47 and the inlet aperture 39 of the battery box 26, and a second sealing member 53 may be provided around the intake port 48 and the outlet aperture 40 of the battery box 26.

Therefore, the interior space of the battery box 25 is effectively sealed from the ambient atmosphere. The thermal control unit 43 may be detachably mounted to the side wall panel 35 of the battery box 25, for example by any known releasable attachment elements. This may advantageously enable easy detachment of the thermal control unit 43 from the battery box 25, for example for maintenance or replacement, or to be attached to a different battery pack.

A temperature sensor 54 (see Fig. 9) is advantageously provided within the interior space of the battery box 25 and is connected to a controller 55 to control operation of the air conditioning unit 46 and fan 45. The controller 55 may comprise a vehicle controller for the REEV to which the battery pack 15 is connected. Alternatively, the controller 55 may comprise a separate dedicated battery pack controller. The controller 55 may comprise a processor and a memory, and the memory may have stored various parameters for controlling operation of the thermal control unit. For example, the memory may store upper and lower threshold temperatures for which the thermal control unit may be turned on or off, or at which the thermal control unit may be controlled to heat or cool the interior space of the battery box 26.

- 12 The battery pack 15 also comprises a battery management system (BMS) 56 which comprises a controller connected to each battery module 41 and to the controller 55. Referring still to Fig. 9, the battery pack 15 includes positive and negative power output connectors 57,58. The battery modules 41 are electrically connected in series with one battery module 41 at the positive end of the series connected battery modules 41 connected to the positive power output connector 57 via a positive contactor 59. The battery module 41 at the negative end of the series connected battery modules 41 is connected to the negative power output connector 58 via a negative contactor 60. The positive and negative contactors 59, 60 are connected to the BMS 56 and are controllable by the BMS to open and close the connections to the positive and negative power output connectors 57,58 respectively. In an alternative embodiment, the controller 55 may be connected directly to the positive and negative contactors 59, 60 to control opening and closing of the connections to the positive and negative power output connectors 57,58 respectively.

In use, the fan 45 causes air to circulate within the battery pack 14,15, to generate a circulating air flow shown by arrows F in Fig. 8. The fan 45 draws air from the interior space of the battery box 25, through the outlet aperture 40, into the thermal control unit 43 and blows the air through the air conditioning unit 46 where the air is cooled or heated as necessary, before continuing through the inlet aperture 39 and into the passage 37 beneath the battery modules 41. The air then flows through the vent holes 38 in the floor panel 36, through the air flow passages 42 between the battery modules

41 and back to the interior space of the battery box 25. As such, the battery modules 41 can be maintained at a desired optimum operating temperature by passing cooling air flow between the modules 41. In colder conditions, the heat generated by the battery modules 41 may be insufficient to maintain the battery modules 41 at the optimum operating temperature, in which case the controller 55, in response to a temperature signal from the temperature sensor 54, would control the air conditioning unit 46 to heat the circulating air flow F to additionally heat the battery modules 41.

Alternatively, in hotter conditions, the heat generated by the battery modules 41 may be cause the interior of the battery box 26 to rise to a temperature above the optimum operating temperature of the battery modules 41, in which case the controller 55, in response to a temperature signal from the temperature sensor 54, would control the air conditioning unit 46 to cool the circulating air flow F to cool the battery modules 41.

-13The battery pack 15 may include additional or alternative temperature sensors connected to the controller 55, as shown in dashed lines in Fig. 9. A first additional temperature sensor 61 may be provided at or within the inlet aperture 39 to measure air temperature flowing into the battery box 26. A second additional temperature sensor 62 may be provided at or within the outlet aperture 40 to measure air temperature flowing out of the battery box 26. The controller 55 may control operation of the fan 45 and the air conditioning unit 46 in dependence upon temperature signals received from one or both of the first and second additional temperature sensors 61, 62. For example, the controller 55 may compare a temperature difference At between a temperature measured at the inlet aperture 39 and a temperature measured at the outlet aperture 40. For example, the controller 55 may control the thermal control unit 43 to operate whilst the outlet temperature remains a predetermined temperature difference above or below a predetermined threshold temperature value or temperature range. In addition, or alternatively, the controller 55 may control the thermal control unit 43 to operate if a temperature difference At between a temperature measured at the inlet aperture 39 and a temperature measured at the outlet aperture 40 is greater than a predetermined threshold temperature range, that is a threshold size of At.

Each battery module 41 preferably includes within its own control electronics, its own temperature sensor. As mentioned above, each battery module 41 may advantageously be connected to the BMS 56 which in turn is connected to the controller 55. The controller 55 may therefore control operation of the thermal control unit 43 by comparing the detected temperature from the battery modules 41 with the detected temperature within the battery box 25 from one of the temperature sensors 54, 61, 62 and heating or cooling the circulating air to heat or cool the battery modules 41 as necessary. The thermal control unit 43 may, for example, be controlled such that a difference between the detected temperature from the battery modules 41 and the detected temperature within the battery box 25 from one of the temperature sensors 54,

61, 62 is maintained at or lower than a predetermined temperature difference.

Although the battery box 25 is described above as being constructed of composite panels 28 comprising a polypropylene core 29 with fibre-reinforced polypropylene skins 31, the invention is not limited to this particular configuration of composite panel

28. For example, the invention may alternatively comprise a composite panel made of other materials, such as other plastic forming the core with a plurality of air spaces

-14formed therein. Also the panel skins 31 maybe of other configurations within the scope of the invention, such as other plastic, with or without fibre reinforcement. Examples include glass fibre reinforced plastic (GFRP) and carbon fibre reinforced plastic (CFRP) materials.

The core maybe of other configurations other than a honeycomb structure, provided the core still comprises a plurality of air cavities therein to provide the advantageous light weight and thermal insulating properties described above. For example, the core may comprise a foam material.

In the exemplary embodiment shown, a sealing element 32 such as a gasket is advantageously provided between the box body 26 and the lid 27. However, the invention is not intended to be limited to this configuration and in an alternative exemplary embodiment, as described above, a sealing gasket may be omitted.

In the exemplary embodiments illustrated, the EMC shielding is provided as a lining on an inner surface of the battery box 25. However, the invention is not intended to be limited to such configuration, and in an alternative embodiment, an EMC shielding maybe provided as a lining embedded within the composite sandwich panels 28. For example, the EMC lining may be provided between the core 29 and one of the skins 31. Alternatively, the EMC lining may be embedded within the core 29, or may be formed integrally within one of the skins 31. For example, the skins may be formed of fibreglass fibres and a layer of EMC shielding material, such as woven metallic fibres, embedded in polypropylene. In any such alternative configuration of EMC shielding, it will be appreciated that the EMC shielding material in the box body 26 may be electrically connected to the EMC shielding material in the lid 27. Any such connection means or configuration described above may be used for such electrical connection.

The embodiments of the invention shown in the drawings and described above are exemplary embodiments only and are not intended to limit the scope of the invention, which is defined by the claims hereafter. It is intended that any combination of nonmutually exclusive features described herein are within the scope of the present invention.

Claims

Claims

1. A battery box for a battery pack of an electric vehicle comprising:

a box portion comprising a base and a plurality of side walls defining an interior 5 space and an upper opening;

a lid secured over the upper opening to close the box portion;

wherein at least one of the base wall, side walls and lid comprises a composite panel comprising a core having a plurality of cavities therein and first and second skins respectively bonded to first and second opposite sides of the core.

io
2. A battery box according to claim l wherein all of the base, side walls and lid comprise the composite panels.
3. A battery box according to claim l or claim 2 wherein the core comprises a 15 honeycomb structure.
4. A battery box according to claim 3 wherein the honeycomb core is made of polypropylene and the skins comprise glass fibre reinforced polypropylene sheets.

20 5. A battery box according to any preceding claim wherein at least two out of the base and side walls are integrally formed from a single composite panel.

6. A battery box according to any preceding claim, further comprising a floor panel parallel to and spaced from the base panel to define a passage between the floor panel

25 and the base panel.

7. A battery box according to claim 6 wherein the floor panel includes a plurality of apertures extending therethrough to fluidly communicate the passage with the remaining interior space of the box portion.

8. A battery box according to any preceding claim wherein a side wall of the box portion includes an outlet vent aperture extending therethrough proximate an upper portion thereof, and an inlet vent aperture extending therethrough proximate a lower portion thereof.

-ι69. A battery box according to claim 8 when dependent on claim 7 wherein the inlet vent communicates with the passage between the floor panel and the base panel, and the outlet vent communicates with the remaining interior space of the box portion.
5 10. A battery box according to claim 8 or claim 9 wherein the area of the outlet vent aperture is substantially the same as the area of the inlet vent aperture.

11. A battery box according to any preceding claim wherein the side wall panels, base panel and lid include an EMC shielding.

12. A battery box according to claim 11 wherein the EMC shielding comprises a lining of woven fabric of metallic fibres.

13. A battery box according to claim 11 wherein the EMC shielding comprises a

15 coating of conductive metallic paint.

14. A battery box according to any of claims 11 to 13 wherein the EMC shielding comprises a lining on the inside surfaces of the side wall panels, base panel and lid.

20 15. A battery box according to any of claims 11 to 13 wherein the EMC shielding comprises a layer of material embedded within at least one of the side wall panels, base panel and lid.

16. A battery box according to any of claims 11 to 15 wherein the EMC shielding

25 provided on the lid is electrically conductively connected to the EMC shielding provided on the side wall panels and the base.

17. A battery box according to claim 16 wherein a conductive connecting element is connected to the lid and a side wall panel to electrically conductively connect the EMC

30 shielding provided on the lid and side wall panels and the base.

18. A battery box according to any preceding claim wherein an airtight seal is formed at the junction where each side panel, base panel and the lid abut.

-1719· A battery box according to any preceding claim comprising a sealing element disposed between the box portion and the lid to form an air-tight seal between the box portion and the lid.

5 20. A battery box according to any preceding claim wherein a closure element extends from the lid to the box portion to secure the lid to the box portion.

21. A battery box according to claim 20 wherein the closure element is formed integrally with the lid.

22. A battery box according to claim 20 or claim 21 wherein the closure element extends around substantially the entire perimeter of the lid and box portion.

23. A battery box according to any of claims 20 to 22 wherein the closure element

15 depends from a perimeter edge of the lid.

24. A battery box substantially as herein described with reference to the accompanying drawings.

20 25. A method of manufacturing a battery box for a battery pack of an electric vehicle comprising forming a box portion comprising a base and a plurality of side walls defining an interior space and an upper opening, and a lid for securing over the upper opening to close the box portion, at least one of the base wall, side walls and lid comprising a composite panel comprising a core having a plurality of cavities therein

25 and first and second skins respectively bonded to first and second opposite sides of the core.

26. A method according to claim 25 comprising forming all of the base, side walls and lid from the composite panels.

27. A method according to claim 25 or claim 26 comprising forming at least two out of the base and side walls are integrally from a single composite panel.

28. A method according to any of claims 25 to 27, further comprising providing a

35 floor panel parallel to and spaced from the base panel to define a passage between the floor panel and the base panel.

-1829. A method according to claim 28 comprising providing a plurality of apertures extending through the floor panel to fluidly communicate the passage with the remaining interior space of the box portion.

30. A method according to any of claims 25 to 29 comprising providing an outlet vent aperture extending through a side wall of the box portion proximate an upper portion thereof, and an inlet vent aperture extending through the side wall of the box portion proximate a lower portion thereof.

31. A method according to claim 30 when dependent on claim 29 comprising providing the inlet vent communicating with the passage between the floor panel and the base panel, and the outlet vent communicating with the remaining interior space of the box portion.

32. A method according to claim 30 or claim 31 comprising forming the area of the outlet vent aperture as substantially the same as the area of the inlet vent aperture.

33. A method according to any of claims 25 to 32 comprising providing the side wall 20 panels, base panel and lid with an EMC shielding.

34. A method according to claim 33 comprising forming the EMC shielding of a lining of woven fabric of metallic fibres.

25 35· A method according to claim 33 comprising forming the EMC shielding of a coating of conductive metallic paint.

36. A method according to any of claims 33 to 35, comprising providing the EMC shielding as a lining on the inside surfaces of the side wall panels, base panel and lid.

37. A method according to any of claims 33 to 35, comprising providing the EMC shielding as a layer of material embedded within at least one of the side wall panels, base panel and lid.

-1938. A method according to any of claims 33 to 37 comprising providing the EMC shielding on the lid being in electrical conductive connection with the EMC shielding provided on the side wall panels and the base.

5 39. A method according to claim 38 comprising providing a conductive connecting element connected to the lid and a side wall panel to electrically conductively connect the EMC shielding provided on the lid and side wall panels and the base.

40. A method according to any of claims 25 to 39 comprising forming an airtight
10 seal at the junction where each side panel, base panel and the lid abut.

41. A method according to any of claims 25 to 40 comprising providing a sealing element disposed between the box portion and the lid to form an air-tight seal between the box portion and the lid.

42. A method according to any of claims 25 to 41 comprising providing a closure element extending from the lid to the box portion to secure the lid to the box portion.

43. A method according to claim 42 comprising forming the closure element 20 integrally with the lid.

44. A method of manufacturing a battery box for a battery pack of an electric vehicle substantially as herein described with reference to the accompanying drawings.

Intellectual

Property

Office

Application No: GB1615190.4 Examiner: Mr Tony Walbeoff