WO2013133740A1

WO2013133740A1 - A heat exchanger arrangement for a vehicle and a method for providing adaptive heat dissipation for a vehicle

Info

Publication number: WO2013133740A1
Application number: PCT/SE2012/050256
Authority: WO
Inventors: Erik Hjerpe; David Sturk; Kyriakos Vavalidis; Heath Knight-Newbury
Original assignee: Autoliv Development Ab
Priority date: 2012-03-07
Filing date: 2012-03-07
Publication date: 2013-09-12

Abstract

The present invention relates to a heat exchanger arrangement (4) arranged to be mounted to a vehicle (1). The heat exchanger arrangement (4) is arranged to conduct heat from at least one component (2, 3) in the vehicle (1) to ambient air. The heat exchanger arrangement (4) is arranged to be expandable from a first state (S1) to a second state (S2). Furthermore, the heat exchanger arrangements volume and heat conductivity is increased when the heat exchanger arrangement (4) is expended from the first state (S1) to the second state (S2).The present invention also relates to a corresponding method.

Description

A HEAT EXCHANGER ARRANGEMENT FOR A VEHICLE AND A METHOD FOR PROVIDING ADAPTIVE HEAT DISSIPATION FOR A VEHICLE

DESCRIPTION OF THE INVENTION

The present invention relates to a heat exchanger arrangement in a vehicle, the heat exchanger arrangement being arranged to conduct heat from at least one component in the vehicle to ambient air.

Today, vehicles comprise different electrical systems which handle large electrical currents, and in particular for electrically powered vehicles, some components can during certain conditions radiate a large amount of heat which needs to be dissipated.

As an example, if the battery system of an electrically powered vehicle is damaged, there is a risk that it starts to generate excessive amounts of heat, e.g. as a consequence of a short. As another example, for certain failure circumstances such as a collision, the battery system needs to be rapidly emptied of its electrical capacity by leading electrical current through a resistive load. However, a conventional heat exchanger needs large surfaces so as to maximize its potential to establish heat gradients and thus promote effective heat transfer away from the heat source. This results in bulky constructions, and there may be a need for dissipating more heat from a vehicle component than what is possible for an existing heat exchanger system. In the case of an additional heat exchanger being present for emergency situations as mentioned above, they require additional volume. This is not desired in vehicles today, where the available volume is limited. It is an object of the present invention to provide a heat exchanger arrangement that has the capacity of dissipating heat from a vehicle component but that adds less volume to the vehicle construction than prior heat exchanger arrangements during normal conditions, i.e. when the heat exchanger arrangement is not in use.

Said object is achieved by means of a heat exchanger arrangement arranged to be mounted to a vehicle. When mounted, the heat exchanger arrangement is arranged to conduct heat from at least one component in the vehicle to ambient air. The heat exchanger arrangement is arranged to be expandable from a first state to a second state. Furthermore, the heat exchanger arrangement's volume and heat conductivity is increased when the heat exchanger arrangement is expended from the first state to the second state.

According to an example, the component includes a resistive arrangement through which an electrical current is fed when at least one certain occurrence occur.

According to another example, the heat exchanger arrangement comprises at least one unit. According to an alternative, said unit comprises at least two metal sheets which are attached to each other in such a way that when gas is inserted between the metal sheets, a honeycomb structure is formed.

According to another alternative, said unit comprises at least one cooling fin, each cooling fin comprising a moveable part that is erectable. When the heat exchanger arrangement is expended from the first state to the second state, an angle between said moveable part and a base plate is increased.

Other examples are disclosed in the dependent claims. Said object is also achieved by means of a method for providing adaptive heat dissipation for a vehicle, the method comprising the steps of:

detecting that at least one component in a vehicle needs more heat dissipation than presently is available; and

expanding a heat exchanger arrangement from a first state to a second state. The heat exchanger arrangement's volume and heat conductivity is increased when the heat exchanger arrangement is expended from the first state to the second state, such that heat from said component is transferred to ambient air.

A number of advantages are provided by means of the present invention. Mainly, an enhanced capacity for dissipating heat is provided, with a relatively small added space during normal conditions .

The present invention is applied in a situation where the existing cooling system is not capable of handling a rising heat level, for example generated during battery drainage in an emergency situation. The heat exchanger arrangement according to the present invention will offer capabilities to handle such a rising heat level without normally occupying much space, in contrast to conventional heat exchangers.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described more in detail with reference to the appended drawings, where

Figure 1 shows a schematical side view of a first example of a vehicle equipped with the expandable heat exchanger arrangement according to the present invention in a first state; Figure 2 shows a schematical side view of the first example the vehicle equipped with the expandable heat exchanger arrangement according to the present invention in a second state;

Figure 3 shows a schematical side view of a second and third example of a vehicle equipped with the expandable heat exchanger arrangement according to the present invention in a first state;

Figure 4 shows a schematical side view of the second and third example the vehicle equipped with the expandable heat exchanger arrangement according to the present invention in a second state;

Figure 5 shows a schematical perspective view of a first example of an expandable heat exchanger arrangement according to the present invention in a first state;

Figure 6 shows a schematical perspective view of a first example of an expandable heat exchanger arrangement according to the present invention in a second state; Figure 7 shows a schematical perspective view of a second example of an expandable heat exchanger arrangement according to the present invention in a first state;

Figure 8 shows a schematical perspective view of a second example of an expandable heat exchanger arrangement according to the present invention in a second state; and Figure 9 shows a flowchart for a method according to the present invention.

DETAILED DESCRIPTION

With reference to Figure 1, showing a first example, there is a vehicle 1 which is electrically powered by means of a battery system 2 which is positioned at the lower part of the vehicle 1. Below the battery system 2 is a resistive discharge component 3 placed, through which the battery system 2 may be discharged if necessary. Adjacent the resistive discharge component 3, a heat exchanger arrangement 4 is positioned since the resistive discharge component 3 radiates heat when a discharge takes place. According to the present invention, with reference also to Figure 2, the heat exchanger arrangement 4 is arranged to be expandable from a first state SI to a second state S2, the heat exchanger arrangement volume and heat conductivity being increased when the heat exchanger arrangement 4 is expended from the first state SI to the second state S2. The states SI, S2 are indicated in the examples illustrated in Figure 3-6.

In this way, when there is no need for the heat exchanger arrangement 4 to conduct heat, i.e. during normal conditions, it is in the first state SI and then occupies a relatively small space. When the need for conducting heat arises, the heat exchanger arrangement 4 is expanded to the second state S2.

Such a need may for example be that the battery system 2 has to be discharged through the resistive discharge component 3 at an emergency situation such as a failure. According to another example, the battery system 2 may be damaged such that it starts to generate excessive amounts of heat itself, e.g. as a consequence of shorts. The heat will then be conducted to the heat exchanger arrangement 4 via the resistive discharge component 3. If a risk of such a generation of excessive amounts of heat in the battery system 2 is detected, the battery system 2 may be determined to be rapidly emptied through the resistive discharge component 3 before any failure occurs in the battery system 2. The causes of the situations above may vary, and may occur when running the vehicle as well as during a post-crash period, i.e. after a collision.

As these scenarios normally are applied in an emergency situation when the present cooling conditions are not capable of handling the heat generated during drainage, the expandable heat exchanger arrangement 4 will offer sufficient cooling capabilities without occupying much space when not needed. As shown in Figure 1, the heat exchanger arrangement 4 is located under the floor 5 of the vehicle 1 and is mainly constituted by a relatively flat unit which does not have any influence regarding a normal vehicle ground clearance Gl . In the event of a failure mode causing excessive amounts of heat to be generated beyond what the ordinary cooling system is capable of handling when driving the vehicle, a warning system will alert the driver who, at that point, is recommended to slow down or stop the vehicle 1. The heat exchanger arrangement 4 will be expanded when this can be done without imposing a negative effect on the driving capabilities, since the normal vehicle ground clearance Gl is reduced to a reduced vehicle ground clearance G2, shown in Figure 2, when the heat exchanger arrangement 4 is expended from the first state SI to the second state S2. In this context, the term vehicle ground clearance should be considered to be constituted by the shortest distance between the lower side of a stationary vehicle and the ground 7, where the ground 7 is flat. The wheels 8, 9, which normally are in contact with the ground 7, should not be considered, but only those parts that are positioned between the respective wheel- pairs . With reference to Figure 3 and Figure 4, showing to a second example, the heat exchanger arrangement 4' is positioned directly below the battery system 2. In this example the heat exchanger arrangement 4' is only arranged to be expanded when excessive amounts of heat are generated in the battery system 2. No resistive discharge component is used in this example. This arrangement enables a more efficient heat dissipation from the battery system 2 since there is no resistive discharge component between the battery system 2 and the heat exchanger arrangement 4'.

According to a third example with renewed reference to Figure 3 and Figure 4, in addition to a first heat exchanger arrangement 4' corresponding to the heat exchanger arrangement disclosed in the second example, a second heat exchanger arrangement 4'', marked with dotted lines is positioned at a resistive discharge component 3'', also marked with dotted lines are comprised in the vehicle 1. The resistive discharge component 3' ' is positioned a certain distance from the battery system 2 and connected to the battery system 2 by means of a suitable conductor 6.

Thus, in the third example, there are two different heat exchanger arrangements 4', 4'' that are adapted for different situations; the first heat exchanger arrangement 4' is expanded if excessive amounts of heat are generated in the battery system 2, and the second heat exchanger 4'' arrangement is expanded if it is determined that the battery system 2 should be rapidly emptied through the resistive discharge component 3' ' . In certain situations, both heat exchanger arrangements 4', 4'' may have to be expanded; if both excessive amounts of heat are generated in the battery system 2 and the battery system 2 should be rapidly emptied through the resistive discharge component 3' ' at the same time.

For all examples above, in order to control the heat exchanger arrangement 4, 4', 4'', a control unit 10 is placed in the vehicle. The control unit 10 is also arranged to control possible rapid emptying of the battery system 2 through the resistive discharge component 3, 3' ' . The control unit 10 also comprises, or alternatively is connected to, diagnose means 11 that are arranged to provide basis for decisions regarding expansion of heat exchanger arrangements 4, 4', 4'' and/or rapid emptying of the battery system 2. Communication between the control unit 10 and other components such for example as the battery system 2 and the heat exchanger arrangements 4, 4', 4'' may take place via a data bus 12. The control unit 10 and/or the diagnose means 11 may be comprised in the heat exchanger arrangement 4, 4', 4'^'.

In the following, two examples of how a heat exchanger arrangement according to the above may be configured are disclosed .

With reference to Figure 5, a first example of a flat unit 13 mainly constituting the heat exchanger arrangements 4, 4', 4'' discussed above is shown. The flat unit 13 comprises a first metal sheet 14, a second metal sheet 15, a third metal sheet 16 and a fourth metal sheet 17, where the metal sheets 14, 15, 16, 17 are attached to each other by means of strings 18, 19, 20, 21, 22, 23, 24, 25 of an adhesive compound such as glue, and together have a first height HI. For increased clarity, only the strings 18, 19, 20, 21, 22, 23, 24, 25 of adhesive compound between the first metal sheet 14 and the second metal sheet 15 are shown, although such strings are positioned between the second metal sheet 15 and the third metal sheet 16 as well as between the third metal sheet 16 and the fourth metal sheet 17.

The strings positioned between the second metal sheet 15 and the third metal sheet 16 are shifted positions along an extensions perpendicular to the main extension of the strings such that one less string is present between the second metal sheet 15 and the third metal sheet 16. This special arrangement is both obvious and necessary in order to achieve the result disclosed below. Furthermore, with reference to Figure 5 and Figure 6, a manifold 26 is connected to outer apertures 27, 28, 29, 30, 31, 32, 33 in the first sheet 14. In Figure 6, the manifold 26 is excluded to more clearly show the outer apertures 27, 28, 29, 30, 31, 32, 33. By means of the manifold 26, when the flat unit 13 is about to be expanded to the second state S2, expanding gas from a detonated pyrotechnical charge device 34 is directed into the flat unit 13. By means of inner apertures (not shown) , suitably positioned in the inner metal sheets 15, 16, i.e. the second metal sheet 15 and the third metal sheet 16, the expanding gas is distributed within the flat unit 13. The flat metal sheets 14, 15, 16, 17 are attached to each other by means of said strings 18, 19, 20, 21, 22, 23, 24, 25 of adhesive compound in such a way that the gas, which forces itself between the sheets 14, 15, 16, 17 via the apertures, expands the metal sheets 14, 15, 16, 17 in a honeycomb structure, as shown in Figure 6, having a second height H2 which exceeds the first height HI. Figure 5 thus shows the first state SI and Figure 6 shows the second state S2.

In practice, the second height H2 is many times larger than the first height HI.

In the channels formed, air may flow. It is to be noted, that the flat unit 13 comprises gables 35, 36, shown de-attached in Figure 5 with dash-dotted arrows Al, A2 schematically indicating their intended mounting, in order to contain the inserted gas such that the metal structure is deformed to the honeycomb structure. Since those edges where the gables are intended to be placed are deformed, the gables 35, 36 should, at least to a certain extent, be deformable. In any way, the gables 35, 36 should be arranged to be de-attached from the honeycomb structure before it is completely formed. Since the distance between the outer apertures 27, 28, 29, 30, 31, 32, 33 in the first sheet 14 will decrease as the honeycomb structure is formed, the manifold 26 should be made flexible in order to adapt to this change. The manifold may furthermore be arranged to be de-attached from the honeycomb structure before it is completely formed.

It is also conceivable to dispense with the gables. In that case, the inserted gas creates a pulse of such a force, expanding through the inner apertures and acting on the fourth metal sheet 17, pressing it downwards such that the honeycomb structure is formed.

With reference to Figure 7, a second example of a flat unit 37 mainly constituting the heat exchanger arrangements 4, 4', 4'' discussed above is shown. The flat unit 37 comprises a base plate 38 and a first cooling fin 39, second cooling fin 40 and third cooling fin 41, each cooling fin 39, 40, 41 having a corresponding attachment part 42, 43, 44 that is attached to the base plate 38 and a corresponding moveable part 45, 46, 47 that can be bent upwards. The flat unit 37 further comprises a first expandable element 48, second expandable element 49 and third expandable element 50. In the first state SI, each expandable element 48, 49, 50 is deflated and positioned between a corresponding moveable part 45, 46, 47 and the base plate 38. Each expandable element 48, 49, 50 is partly attached to a corresponding moveable part 45, 46, 47 and partly attached to the base plate 38. A pyrotechnical charge device 51 is connected to the expandable elements 48, 49, 50 by means of a manifold 52.

By means of the manifold 52, when the flat unit 37 is about to be expanded to the second state S2 as shown in Figure 8, expanding gas from the pyrotechnical charge device 51 is directed into the expandable elements 48, 49, 50 such that the expandable elements 48, 49, 50 are inflated and expand such that the moveable parts 45, 46, 47 of the cooling fins 39, 40, 41 are lifted away from the base plate 38. The expandable elements 48, 49, 50 thus work as balloons which are rapidly filled with gas such that they exert a moving force on the respective moveable parts 45, 46, 47.

With reference to Figure 9, the present invention also relates to a method for providing adaptive heat dissipation for a vehicle. The method comprises the steps of:

53: detecting that at least one component in a vehicle needs more heat dissipation than presently is available; and

54: expanding a heat exchanger arrangement from a first state SI to a second state S2. The heat exchanger arrangement's volume and heat conductivity is increased when the heat exchanger arrangement is expended from the first state SI to the second state S2, such that heat from said component is transferred to ambient air.

The step of detecting that at least one component in a vehicle needs more heat dissipation than presently is available comprises detecting the need for drainage of electric capacity since the need for drainage of electric capacity implies that at least one component in the vehicle needs more heat dissipation than presently is available.

The present invention is not limited to the examples above, but may vary within the scope of the appended claims. For example, the heat exchanger arrangement may alternatively comprise more than one flat unit. In the case of several flat units being comprised in the heat exchanger arrangement, these may be activated consecutively or section-wise in order to develop temperature gradients, which may induce a "chimney- effect" which in turn will develop a streaming of air, convectively cooling the structure of the heat exchanger arrangement .

Furthermore, in order to improve the circulation in the heat exchanger arrangement, a fan may be used to assist the flow cooling air. In this case, where the vehicle is equipped with a battery system, the use of the fan may not only provide assisting flow of the cooling air, but also add to the capability of the emergency system to drain the electric capacity of the battery system.

The heat exchanger arrangement may be constituted of honeycomb or cooling fins or any other type of structure capable of expanding from a relatively flat structure to a structure providing a large surface for heat exchanging capabilities.

The number of metal sheets in the first example of a flat unit 13 may vary, but in order to acquire a honeycomb structure in the expanded second state S2, there should be at least two metal sheets. Instead of using an adhesive compound, other adhering techniques are of course conceivable such as welding or riveting.

The pyrotechnical charge device 34, 51 may be any type of suitable gas generator or pressurized gas container with a release valve. The number of moveable parts 45, 46, 47 with cooling fins 39, 40, 41 in the second example of a flat unit 37 may of course vary. It is furthermore conceivable that the cooling fins 39, 40, 41 are erected in some other suitable way. For example, they may be spring-loaded, where a lock is released when the cooling fins 39, 40, 41 are to be erected. Alternatively, they may be erected by means of an electric motor. In such a case the movement of the moveable parts could be reversed so that the heat exchanger returned to its pre-activated dimensions. In the case of pyrotechnical inflation, multiple pyrotechnic devices could be used instead of a single device and manifold as described above.

Generally, when the flat unit 37 is expended from the first state SI to the second state S2, an angle β between each moveable part 45, 46, 47 and the base plate 38 is increased.

The flat unit or flat units comprised in the heat exchanger arrangement are generally constituted by units of any shape, which are expandable from a first state SI to a second state SI as described above.

The diagnose means 11 may be comprised in the heat exchanger arrangement .

For different reasons, it may not be desired to have a rapid emptying of the battery system 2, but a slower emptying of the battery system 2, for example to avoid thermal runaway in the battery cells of the battery system 2. The properties of the emptying of the battery system 2 may be adjusted by means of adjusting the resistive discharge component 3, 3' ' .

Generally, the resistive discharge component 3, 3' ' is constituted by a resistive arrangement.

The number of outer apertures 27, 28, 29, 30, 31, 32, 33 in the first sheet 14 may vary, and the manifold is adapted to the number of outer apertures present. In its least complicated form, it is conceivable that there is only one outer aperture that is connected to a gas generator of some sort. A gas pulse would then be fed through said outer aperture and fed through at least one inner aperture in each of the second metal sheet 15 and the third metal sheet 16. Preferably, in this case, there are no gables, but the gas pulse acting on the fourth metal sheet 17 makes the honeycomb structure unfold.

Instead of a battery system, the vehicle 1 may alternatively comprise a fuel cell system, which also may need the heat exchanger arrangement according to the present invention.

The vehicle may have any type of propulsion, and a possible emerging need for heat dissipation which is provided by means o f the heat exchanger arrangement according to the present invention .

Claims

CLAIMS 1. A heat exchanger arrangement (4) arranged to be mounted to a vehicle (1), the heat exchanger arrangement (4) being arranged to conduct heat from at least one component (2, 3) in the vehicle (1) to ambient air when mounted to the vehicle, characterized in that the heat exchanger arrangement (4) is arranged to be expandable from a first state (SI) to a second state (S2), the heat exchanger arrangements volume and heat conductivity being increased when the heat exchanger arrangement (4) is expended from the first state (SI) to the second state (S2) .

2. A heat exchanger arrangement according to claim 1, characterized in that said component includes a resistive arrangement (3, 3'') through which an electrical current is fed when at least one certain occurrence occur.

3. A heat exchanger arrangement according to any one of the claims 1 or 2, characterized in that said component includes a battery system (2) .

4. A heat exchanger arrangement according to any one of the claims 1 or 2, characterized in that said component includes a fuel cell system.

5. A heat exchanger arrangement according to any one of the previous claims, characterized in that the heat exchanger arrangement (4) comprises at least one unit (13) which in turn comprises at least two metal sheets (14, 15, 16, 17) which are attached to each other in such a way that when gas is inserted between said metal sheets (14, 15, 16, 17), a honeycomb structure is formed.

6. A heat exchanger arrangement according to any one of the claims 1-4, characterized in that the heat exchanger arrangement comprises at least one unit (37) which in turn comprises at least one cooling fin (39, 40, 41), each cooling fin (39, 40, 41) comprising a moveable part (45, 46, 47) that is erectable such that when the heat exchanger arrangement is expended from the first state (SI) to the second state (S2), an angle (β) between said moveable part (45, 46, 47) and a base plate (38) is increased.

7. A heat exchanger arrangement according to any one of the previous claims, characterized in that it is arranged to be mounted to the vehicle (1) such that a normal vehicle ground clearance (Gl) is reduced to a reduced vehicle ground clearance (G2) when the mounted heat exchanger arrangement (4, 4', 4'') is expended from the first state (SI) to the second state (S2) .

8. A heat exchanger arrangement according to any one of the previous claims, characterized in that a control unit (10) is arranged to control expansion of heat exchanger arrangements (4, 4', 4'') and/or dissipating electrical energy through a resistive discharge component (3, 3' ' ) .

9. A heat exchanger arrangement according to claim 8, characterized in that the control unit (10) is arranged to control emptying of the battery system (2) through the resistive discharge component (3, 3'')

10. A method for providing adaptive heat dissipation for a vehicle, the method comprising the step: (53) detecting that at least one component in a vehicle needs more heat dissipation than presently is available ;

characterized in that the method further comprises the step:

(54) expanding a heat exchanger arrangement from a first state (SI) to a second state (S2), the heat exchanger arrangement's volume and heat conductivity being increased when the heat exchanger arrangement is expended from the first state (SI) to the second state (S2), such that heat from said component is transferred to ambient air.