Electrical mounting element for a vehicle thermally regulated by heat pipes

Description

[0001] The invention relates to an electrical storage device for a vehicle, configured to power at least one electric traction motor of the vehicle, thermally controlled using heat pipes. The invention finds a particularly advantageous, but not exclusive, application with motor vehicles.

[0002] It is well known in the field of electrical storage that the thermal management of batteries plays an important role in their development. Indeed, the operation, efficiency and lifespan of an electric cell are directly influenced by its temperature. It is also known that the temperature of a battery must be maintained in a range of around 15°C to 35°C and more specifically between 20°C and 30°C.

[0003] This temperature maintenance must be ensured during the driving phase of the vehicle equipped with electric cells, but also during the stopping phases and, in particular, during the charging phases of the electric cells. In addition, rapid charging of the electric cells generally causes an increase in heat within them. It is then necessary to cool these electric cells in order to preserve their lifespan. Similarly, climatic conditions or geographical location can strongly influence the temperature of the electric cells. In cold climatic conditions where the temperature of the electric cells can drop below a determined threshold, it is recommended to warm the electric cells to remain within the optimal operating temperature ranges stated above.

[0004] Due to the particularly high cost of electric cells compared to the total cost of the vehicle, it is essential to ensure efficient temperature control of the latter. In addition, the notion of size and weight plays an important role in the dimensioning of electric cells, so as to improve the ratio between performance and cost.

[0005] In this context, it is known to place against one face of an electric cell a heat pipe thermally connected to a heat exchanger, in order to perfect the heat transfer from the electric cell to the heat exchanger.

[0006] However, a thermal gradient forms within the electric cell. Indeed, since the heat pipe is placed against a single face of the electric cell, the cooling of the electric cell is inhomogeneous. The other faces of the electric cell are therefore not cooled in the same way. This disadvantage becomes all the more important since a new technique for charging the electric storage device has recently appeared. It consists of charging this electric storage device under a high voltage and amperage, so as to charge the electric storage device in a maximum time of a few tens of minutes. This rapid charging involves heating the electric storage device beyond a critical threshold for the electric storage device.

[0007] It must therefore be noted that the known system, although allowing better thermal adjustment of the thermal cell, does not fully address the dual problem of temperature homogeneity within the electric cell and its cooling under critical conditions.

[0008] Documents FR 3056829 A1, CN 107403976 A and US 2010 / 216004 A1 describe relevant prior art electrical storage devices.

[0009] The invention therefore aims to effectively overcome the drawbacks of the prior art by harmonizing temperature control over a larger contact area between the electric cell and the heat pipe. Thus, the lifespan and operation of the latter are improved.

[0010] To this end, the invention relates to an electrical storage device according to claim 1.

[0011] The expression "parallelepiped section" provides information on the shape of the electric cell. In fact, what is meant here is that the electric cell has the shape of a rectangular parallelepiped or a cube, seen along a section plane passing through the electric cell and parallel to an upper face of the latter from which electrical connection pads emerge.

[0012] The heat exchanges between the electrical storage device and the heat exchanger are reversible. Indeed, the heat pipe providing the thermal connection between the electric cell and the heat exchanger can operate in a "cooling" mode for the electric cell or in a "heating" mode for the latter.

[0013] This positioning of the heat pipe on at least two sides of the electric cell creates a large heat exchange surface with the electric cell. In addition, this positioning allows the heat exchanges to be distributed over a larger contact area, further homogenizing the temperature throughout the entire electric cell.

[0014] In addition to improving temperature homogeneity, the invention promotes the drainage of a greater quantity of calories towards the heat exchanger, which is well suited for a rapid charging situation where the electric cell tends to heat up.

[0015] According to the invention, the heat pipe is thermally coupled with at least three faces of the same electric cell.

[0016] According to one feature, the heat pipe is thermally coupled with at least four faces of the same electric cell.

[0017] According to one feature, the heat pipe is thermally coupled with at least five faces of the same electric cell.

[0018] By increasing the number of faces of the electric cell thermally coupled to the heat pipe, the heat exchange is improved due to the increase in the exchange surface, which directly improves the thermal capacity of the electrical storage device. Furthermore, increasing the number of faces of the electric cell thermally coupled to the heat pipe improves the temperature homogenization capacity throughout the electric cell, which considerably improves the capacities of the electrical storage device and makes it more reliable.

[0019] According to one feature, the walls of the heat pipe are made of rigid material.

[0020] According to one feature, the walls of the heat pipe are made of flexible material.

[0021] Here, the term "rigid material" or "flexible material" means that the walls of the heat pipe can have different thicknesses. Indeed, the same material can have its physical properties modified according to its dimensions, and in particular its thickness. For example, the walls of the heat pipe can be composed of Aluminum, or an aluminum alloy, or even Copper and can be described as flexible when the thickness is small or rigid when the thickness is significant. The expressions flexible and rigid are thus to be interpreted in relation to each other.

[0022] In the case of heat pipe walls made of rigid material, the heat pipe forms a mechanical protection for the face of the electrical cell concerned.

[0023] In the case of heat pipe walls made of flexible material, the heat pipe can easily conform to the shape of the electric cell and be easily installed on it, in particular by threading it around the electric cell.

[0024] According to one characteristic, a section of the heat pipe is complementary to the parallelepiped section of the electric cell.

[0025] The "section complementarity", that is to say the geometric resemblance between the inner volume of the heat pipe and the outer periphery of the electric cell, both of parallelepiped shape, improves the heat exchange surfaces and increases the heat transfer capacity of the heat pipe with respect to the electric cell.

[0026] According to one characteristic, the heat pipe comprises a first wall separated from a second wall by a hermetic volume filled with a two-phase fluid.

[0027] In fact, during the transfer of calories between the electric cell and the heat exchanger via the heat pipe, due to the thermodynamic cycle which takes place in the heat pipe, the fluid contained inside the heat pipe can be in a liquid phase or in a gaseous phase.

[0028] According to one feature, the heat pipe comprises at least one spacing device arranged between the first wall and the second wall.

[0029] The hermetic volume, within which the two-phase fluid moves, must be constant to allow the two-phase fluid to perform a thermodynamic cycle under good conditions. In this sense, the spacer device continuously generates and maintains this space between the two walls of the heat pipe creating the hermetic volume of constant thickness.

[0030] According to the invention, the electrical storage device comprises a plurality of electrical cells, each provided with an individual heat pipe thermally coupled with at least the two faces of the same electrical cell.

[0031] According to the invention, the heat pipes surrounding the electric cells are arranged in contact with each other. According to an example not falling within the scope of the invention, the heat pipes surrounding the electric cells are arranged so as to leave a space between each heat pipe. In this second case, there is an air gap between each heat pipe.

[0032] According to one feature, the heat exchanger comprises a plurality of flat tubes on which the plurality of electrical cells rest. The heat exchanger may be configured to be traversed by a heat transfer fluid or by a refrigerant fluid, in particular a phase change fluid.

[0033] Other characteristics, details and advantages of the invention will emerge more clearly on reading the description given below for information purposes in relation to drawings in which: there figure 1 is a general perspective view of the electrical storage device comprising an electrical cell provided with a heat pipe thermally coupled on two of the faces of the electrical cell, the figure 2 is a general perspective view of the electrical storage device comprising an electrical cell provided with a heat pipe thermally coupled on three of the faces of the electrical cell, the figure 3 is a general perspective view of the electrical storage device comprising an electrical cell provided with a heat pipe thermally coupled on three of the faces of the electrical cell according to a second configuration mode, the figure 4 is a general perspective view of the electrical storage device comprising an electrical cell provided with a heat pipe thermally coupled on four of the faces of the electrical cell, the figure 5 is a general perspective view of the electrical storage device comprising an electrical cell provided with a heat pipe thermally coupled on five of the faces of the electrical cell, the figure 6 represents a schematic view of an electrical stage device comprising several electrical cells, each equipped with an individual heat pipe carrying out thermal exchanges with the heat exchanger, the figure 7 represents an overall view of an electrical storage device not falling within the scope of the invention comprising a plurality of electrical cells each provided with their respective heat pipe in thermal relation with a heat exchanger.

[0034] It should first be noted that the figures set out the invention in detail to implement the invention, said figures can of course be used to better define the invention where appropriate.

[0035] In the different figures, identical elements bear the same reference numbers.

[0036] There figure 1 represents a general view, in perspective, of the electrical storage device 1 comprising an electrical cell 2 provided with a heat pipe 3 thermally coupled on two of the faces of the electrical cell 2.

[0037] The electrical cell 2, due to its parallelepiped shape, comprises two large faces 21, two small faces 22, a lower face 23 and an upper face 24 from which emerge electrical connection pads 241, the latter serving to electrically connect the electrical cell 2 to a network.

[0038] The electrical storage device 1 also comprises the heat pipe 3 consisting of two walls 302 delimiting a sealed volume. Each of the walls 302 of the heat pipe 3 comprises an inner surface 303 and an outer surface 307, connected by edges 308. The walls 302 of the heat pipe 3 comprise on their inner surface 303 spacers 304 ensuring an adequate distance between the two walls 302. Between the two walls 302, the heat pipe 3 comprises the sealed volume of two-phase fluid 305, the latter being capable of undergoing a thermodynamic cycle of evaporation and condensation which implements a transport of calories from the electric cell to the heat exchanger.

[0039] According to the invention, the heat pipe 3 is thermally coupled, for example, to one of the two large faces 21 of the electric cell 2 and to one of the two small faces 22 of the electric cell 2 via the external surface 307 of one of the two walls 302 of the heat pipe 3.

[0040] The electrical storage device 1 further comprises a heat exchanger 4, comprising a plurality of flat tubes 42 and a fluid supply portion of the flat tubes 42. In addition, the heat pipe 3 is thermally coupled to the flat tubes 42 of the heat exchanger 4 via the edges 308. The flat tubes 42 delimit a circuit traversed by a fluid or a heat transfer liquid. These flat tubes 42 have an oblong cross-section and are provided with several channels. The flat nature of the tubes 42 makes it possible to rest the electric cell 2 so that it is in direct contact with the flat tube 42, in indirect contact via a wall 302 of the heat pipe 3 interposed between the electric cell 2 and the flat tube 42 of the heat exchanger 4.

[0041] There figure 2 is a general and perspective view of the electrical storage device 1 according to one embodiment, comprising an electrical cell 2 provided with a heat pipe 3 thermally coupled on three faces of the electrical cell 2.

[0042] Similar to the description set out in the figure 1 , the electrical storage device 1 comprises a heat pipe 3 of which only a large face 21 of the electric cell 2 and the two small faces 22 of the electric cell 2 are thermally coupled with the external surface 307 of one of the two walls 302 of the heat pipe 3.

[0043] The heat pipe 3 and the heat exchanger 4 comprise the same components and characteristics as stated in the description of the figure 1 and we will refer to this for their execution.

[0044] An alternative of the electrical storage device 1 comprising an electrical cell 2 provided with a heat pipe 3 thermally coupled on three faces of the electrical cell 2 is described in figure 3 .

[0045] The electrical storage device 1 here comprises a heat pipe 3 of which the two large faces 21 of the electrical cell 2 and only one small face 22 of the electrical cell 2 are thermally coupled with the external surface 307 of one of the two walls 302 of the heat pipe 3.

[0046] Heat pipe 3 and heat exchanger 4 include the same components and characteristics as stated in the description of the figures 1 et 2 and we will refer to this for their execution.

[0047] There figure 4 presents, according to another embodiment, an electrical storage device 1 comprising an electrical cell 2 provided with a heat pipe 3 thermally coupled on four faces of the electrical cell 2.

[0048] The electrical storage device 1 thus comprises a heat pipe 3 of which the two large faces 21 of the electrical cell 2 and the two small faces 22 of the electrical cell 2 are thermally coupled with the external surface 307 of one of the two walls 302 of the heat pipe 3.

[0049] Heat pipe 3 and heat exchanger 4 include the same components and characteristics as stated in the description of the figures 1 à 3 and we will refer to this for their execution.

[0050] There figure 5 presents, according to another embodiment, an electrical storage device 1 comprising an electrical cell 2 provided with a heat pipe 3 thermally coupled on five faces of the electrical cell 2.

[0051] The electrical storage device 1 comprises a heat pipe 3 of which the two large faces 21 of the electric cell 2, the two small faces 22 of the electric cell 2 and the lower face 23 of the electric cell 2 are thermally coupled with the external surface 307 of one of the two walls 302 of the heat pipe 3.

[0052] Heat pipe 3 and heat exchanger 4 include the same components and characteristics as stated in the description of the figures 1 à 4 and we will refer to this for their execution.

[0053] There figure 6 represents a schematic view of an electrical storage device 1 comprising several electrical cells 2, each provided with an individual heat pipe 3 carrying out a thermal transfer 5 with the flat tubes 42 of the heat exchanger 4. The figure 6 shows two examples of embodiment: on the left, the electric cell 2 is in direct contact with the flat tube 42, while on the right, a wall 302 of the heat pipe 3 is interposed between the lower face 23 of the electric cell 2 and the flat tube 42.

[0054] The electric cells 2, as well as their individual heat pipe 3, rest on the flat tubes 42, improving the heat transfer and the temperature homogeneity of the electric cell 2, between its lower face 23 and its upper face 24.

[0055] From a dynamic point of view, the heat transfer 5 between the electric cell 2 and the heat exchanger 4 is carried out in several stages: the calories produced by the electric cell 2 are transmitted to the heat pipe 3, via its large faces 21 and small faces 22 which are thermally coupled with the external surface 307 of one of the two walls 302. These calories are then transferred to a flat tube 42 of the heat exchanger 4 via the edges 308 of the heat pipe 3, or by these edges 308 and by the wall 307 of the heat pipe 3 which is interposed between the lower face of the electric cell 2 and a flat portion of the flat tube 42.

[0056] According to the embodiment described during the figure 5 and on the left part of the figure 6 , the transfer of calories also takes place between the lower face 23 of the electric cell 2 and the external surface 307 of a first wall 302 of the heat pipe 3.

[0057] There figure 7 represents an overall view of the electrical storage device 1 comprising a plurality of electrical cells 2 each provided with their individual heat pipe 3 in thermal relation with a heat exchanger 4 via flat tubes 42.

[0058] The electric cells 2, accompanied by their multi-face heat pipe 3, are therefore aligned along their large faces 21 and along their small faces 22, thus forming a linear and columnar arrangement of the electric cells 2. Furthermore, it is observed that the heat exchanger 4 comprises the plurality of flat tubes 42 and a supply portion 41 of these flat tubes 42. The fluid or heat transfer liquid enters the heat exchanger 4 through this supply portion and is distributed to each flat tube 42.

[0059] A housing 7 holds the electrical storage device 1 by delimiting a receiving space available for each electrical cell 2 accompanied by its heat pipe 3. This housing 7 is composed of a base 72 against which the flat tubes 42 rest and sides 73 delimiting the receiving space for the electrical storage device 1. The housing 7 comprises at least one wedging device 71 for the electrical cells 2 which partitions the receiving space into rows of several electrical cells 2. This wedging device 71 participates in the fixing of the electrical cells 2 and their heat pipe in the housing 7.

[0060] In the embodiment not falling within the definition of the invention illustrated in the figure 7 , an air gap is provided between two adjacent heat pipes 3, and in particular between all the heat pipes 3. This air gap is present between two large faces of two adjacent cells and between two small faces of two other concomitant cells.

[0061] To have a better understanding of the figure 7 , electric cells 2 and their individual heat pipe 3 have been removed from the figure, as well as part of the bottom 72 and sides 73 of the housing 7.

Claims

1. An electric storage device (1) for a vehicle configured to power at least one electric traction motor of the vehicle, the electric storage device (1) comprising a plurality of electric cells (2) of parallelepipedal section delimited by at least two faces (21-23), the electric storage device (1) comprising at least one heat exchanger (4) thermally coupled to the electric cell (2), each of the cells being provided with an individual heat pipe (3) being thermally coupled with the electric cell (2) and thermally coupled to the heat exchanger (4), characterized in that the individual heat pipe (3) is thermally coupled with at least three faces (21-23) of the same electric cell (2), the heat pipes enveloping the electric cells being arranged in contact with each other.

2. The electric storage device (1) according to claim 1, characterized in that the heat pipe (3) is thermally coupled with at least four faces (21-23) of the same electric cell (2).

3. The electric storage device (1) according to claim 2, characterized in that the heat pipe (3) is thermally coupled with at least five faces (21-23) of the same electric cell (2).

4. The electric storage device (1) according to claim 1, characterized in that the walls (302) of the heat pipe (3) are composed of rigid material.

5. The electric storage device (1) according to claim 1, characterized in that the walls (302) of the heat pipe (3) are composed of flexible material.

6. The electric storage device (1) according to claim 1, wherein a section of the heat pipe (3) is complementary to the parallelepipedal section of the electric cell (2).

7. The electric storage device (1) according to claim 4, characterized in that the heat pipe (3) comprises a first wall (302) separated from a second wall (302) by a hermetic volume filled with a two-phase fluid (305).

8. The electric storage device (1) according to claim 7, characterized in that the heat pipe (3) comprises at least one spacing device (304) arranged between the first wall (302) and the second wall (302).

9. The electric storage device (1) according to any one of the preceding claims, wherein the heat exchanger (4) comprises a plurality of flat tubes (42) on which the plurality of electric cells (2) rests.