FR3019688A1 - "MOTOR VEHICLE BATTERY EQUIPPED WITH A DRIVING HEAT PUMP LINE SEPARATED FROM BATTERY ELEMENTS BY FLEXIBLE PARTITION" - Google Patents

Abstract

The invention proposes a battery (10) of a motor vehicle, in particular a traction battery for an electric or hybrid vehicle, comprising: - at least one housing (12) comprising at least one pipe (32) of heat transfer fluid separated in a sealed manner from the interior of the housing (12) by at least one heat exchange partition (34); at least one prismatic electrical energy storage element (18, 20) which is housed in the housing (12) and which is in contact with a planar wafer (30) with a planar face of said partition (34) d heat exchange; characterized in that the heat exchange partition (34) is formed by a membrane of flexible material perfectly matching the wafer (30) of the battery element (18, 20) under the effect of the coolant pressure circulating in contact with said heat exchange partition (34).

Description

FIELD OF THE INVENTION The invention relates to a motor vehicle battery comprising a heat transfer fluid circuit.

TECHNICAL BACKGROUND OF THE INVENTION The invention relates more particularly to a motor vehicle battery, in particular a traction battery for an electric or hybrid vehicle, comprising: at least one housing comprising at least one heat-transfer fluid line separated in a sealed manner from the interior of the housing by at least one heat exchange partition; at least one prismatic electrical energy storage element which is housed in the housing and which is in contact with a flat wafer with a planar face of said heat exchange partition. A motor vehicle of electric or hybrid type is moved, at least in part, by an electric traction motor which is supplied with electricity by a traction battery. Such a battery generally comprises a housing or tray in which are arranged accumulators of electricity, also called battery cells, which are connected in series and / or in parallel. The performance of the traction battery is likely to vary greatly depending on the temperature of the cells. When the battery is subjected to very cold temperatures, for example negative, the cells lose their energy capacity. A fast recharge of the battery can then be prohibited. It is therefore necessary to warm the battery before recharging. Similarly, the use of battery cells produces heat. When the battery is already overheated, either because of a high ambient temperature, or because of alternating too fast discharges and refills, it may be necessary to prohibit the use of the battery to preserve the cells. This generally implies that the vehicle is immobilized while the battery is cooling down to an acceptable operating temperature. To solve these problems, it is known to equip the battery with temperature control means to maintain the battery cells in an optimal operating temperature range.

It has been proposed to equip the battery with a coolant circuit that allows, as needed, to cool or heat the battery cells. The heat transfer fluid is generally a liquid formed of a mixture of water and antifreeze. The known heat transfer fluid circuits have a good ability to convey heat. It is also already known to manufacture battery cells that conduct the heat very well to allow its evacuation via an external face. However, the thermal bridge between the battery cells and the heat transfer fluid circuit does not yet have a sufficiently high conductance to allow the thermal regulation means of the battery to be fully effective. The performance of the battery is affected. In addition, the coolant used is electrically conductive. It is therefore important to ensure that the coolant is electrically isolated from the battery cells to prevent electrical leakage.

Moreover, an electric or hybrid motor vehicle has many organs to be housed in a relatively small space. As a result, the space allocated to the traction battery is reduced. It is therefore preferable that such a battery and equipped with a heat transfer fluid circuit remains compact enough not to unnecessarily clutter the vehicle. BRIEF SUMMARY OF THE INVENTION The invention proposes to solve these problems by proposing a battery of the type described above which is easier to assemble and inexpensive to manufacture. The battery according to the invention is thus characterized in that the heat exchange partition is formed by a membrane of flexible material perfectly matching the edge of the battery element under the effect of the heat transfer fluid pressure flowing in contact. of said heat exchange partition. According to other features of the battery: - the battery comprises a stack of a plurality of battery elements whose contact slots are arranged in a generally coplanar manner, the contact section of all the battery cells of the stack being in contact with a common heat exchange partition; - The coolant pipe is formed in the bottom of the housing and the heat exchange wall is interposed between the bottom of the housing and the battery cells; - The coolant pipe is made in a face of a rigid plate which is covered in a sealed manner and continuous by the heat exchange wall; - A network of at least one heat transfer fluid line travels the face of the rigid plate; - The heat exchange partition is fixed to the plate by gluing, a continuous adhesive bead framing the heat exchange partition; - The heat exchange partition is fixed on the plate 5 by welding, a weld bead framing the heat exchange wall; - The heat exchange partition is fixed by mechanical clamping between a frame and the plate; - The heat exchange wall is made of 10 material with a plate-shaped pocket in which circulates the coolant and which is arranged at the bottom of the housing; each battery element is formed by a cassette which comprises two battery cells which are housed in a metal case which comprises the contact wafer with the heat exchange partition; - The slice of the case is perforated with orifices for heat exchange by direct conduction between the cells and the heat exchange partition. BRIEF DESCRIPTION OF THE FIGURES Other features and advantages of the invention will become apparent upon reading the following detailed description for the understanding of which reference will be made to the accompanying drawings in which: FIG. in longitudinal section along the section plane 1-1 of Figure 2 which shows a motor vehicle traction battery comprising a heat transfer fluid circuit made according to a first embodiment of the invention; FIG. 2 is a view from above of a bottom plate of the battery case of FIG. 1; - Figure 3 is a detail view on a larger scale in longitudinal section which shows the bonding of the periphery of the heat exchange wall on the bottom of the housing of Figure 1; - Figure 4 is a view similar to that of Figure 3 which shows an alternative embodiment in which the heat exchange partition is fixed by welding on the bottom of the housing; - Figure 5 is a view similar to that of Figure 3 which shows an alternative embodiment in which the heat exchange wall is fixed by mechanical clamping against the bottom of the housing; - Figure 6 is a longitudinal sectional view similar to that of Figure 1 which shows a motor vehicle traction battery comprising a heat transfer fluid circuit made according to a second embodiment of the invention. DETAILED DESCRIPTION OF THE FIGURES In the rest of the description, elements having an identical structure or similar functions will be designated by the same references. In the remainder of the description, the longitudinal, vertical and transverse orientations indicated by the "L, V, T" trihedron of the figures will be adopted without limitation. The vertical direction is used as a purely geometrical landmark unrelated to the direction of gravity. There is shown in Figure 1 a traction battery 10 which is intended to equip a motor vehicle mu at least partly by an electric motor. This is for example a vehicle called "hybrid" or a vehicle called "electric". The traction battery 10 is able to supply electrical energy to the electric motor of the vehicle.

The traction battery 10 comprises a housing 12 which is for example made of rigid plastic. The housing 12 has at least one lower bottom 14 and a top cover 16. The bottom 14 is formed by a thick plate of rigid plastic which extends in a horizontal plane. The housing 12 thus comprises a housing delimited between the cover 16 and the bottom 14, in which at least one prismatic element for storing electrical energy is arranged. In general, the battery 10 comprises a plurality of prismatic elements which are stacked longitudinally, as is the case in the example shown in the figures. The prismatic elements are all identical. Each prismatic element is here formed by an assembly containing several cells 20, here two prismatic battery cells. Because of its shape, this assembly will be designated by the term "cassette 18". A battery prismatic cell 20 generally has a flattened rectangular parallelepipedal shape which has two opposite faces 22 and four thin slices 24.

Each face 22 extends here in transverse vertical plane, while one of the slices 24 said lower slice 24 extends orthogonally to the faces 22 in a longitudinal transverse plane. The lower edge 24 of the prismatic cell 20 is intended to be arranged facing an upper face of the base 14. Each battery cell 20 forms an accumulator of electricity. In the embodiment shown in FIG. 1, the battery cells 20 comprise an envelope manufactured by welding two metal sheets against each other so that each wafer 24 of the battery cell 20 has a junction between the two cells. two leaves. The slices 24 thus have a weld bead that surrounds the cell 20.

The two battery cells 20 of a cassette 18 are housed, already stacked longitudinally against each other, in a metal case 26. The metal case 26 itself has two opposite transverse vertical walls 28 connected by a lower edge 30. The lower wafer has a planar shape which extends in a transverse longitudinal plane. Battery cells tend to swell when in use. In known manner, these walls 28 can be deformed to absorb swelling of the cells, thus avoiding deterioration of the battery cells. The metal case 26 is for example made by folding a metal sheet so that the walls 28 enclose the two battery cells 20 longitudinally against each other. Thus, the heat emitted by the cells 20 is capable of being transferred by conduction to the associated case 26 thanks to the large contact area between these two elements. The wall 28 of the case 26 conducts this heat in particular to the lower edge of the case 26. The lower slices 24 of the battery cells 20 are thus arranged in contact with, or at least in the immediate vicinity of, the wafer. 30 of the case 26 thus directly leading the heat emanating from the battery cell 20 to the lower edge of the case 26. Each cassette 18 thus forms an accumulator itself composed of two battery cells 20. A plurality of cassettes 18 are stacked longitudinally against each other in the housing 12. The battery cells 20 of a stack are electrically connected to each other in series or in parallel. The cassettes 18 are arranged so that their flat bottom edge 30 is placed on the plane bottom 14 of the housing 12. The prismatic cassettes 18 are thus stacked longitudinally so that the lower slices are generally coplanar.

For this purpose, a rack 31 for positioning the cassettes 18 is arranged on the bottom 14 of the housing 12. As shown in Figures 1 and 6, the grid 31 is formed of several transverse bars which are spaced longitudinally. The lower edge of each cassette 18 is received in one of these spaces. Each bar of the grid 31 thus forms a spacer between two adjacent cassettes 18. In addition, a shoulder of each cassette 18 is received in vertical support on an associated bar of the grid 31. Thus, this grid 31 makes it possible to support the weight of the cassettes 18 and to keep a regular distance between the cassettes 18. The cover 16 and the bottom 14 have at each of their longitudinal ends opposed vertical wings 33, 35 which are intended to bear longitudinally against the two end cassettes 18 of the stack. Thus, the metal cases 26, the grid 31 and the two opposite wings 33, 35 of the cover 16 and the bottom 14 make it possible to hold the cells 20 longitudinally in the casing 12. In addition, the battery elements 18 are longitudinally pressed together. against the others by the wings 33, 35 of the cover 16 and the bottom 14 and they are held in position by the grid 31 to contain the swelling of the cells. The housing 12 is also equipped with a heat transfer fluid circuit comprising at least one pipe 32 of heat transfer fluid which is sealed from the inside of the housing 12 by a partition 34 of heat exchange. This coolant circuit is intended to regulate the temperature of the battery cells. To allow efficient heat exchange by conduction between the coolant and prismatic battery elements, the partition 34 heat exchange is made of a material considered a good conductor of heat. A first planar face of said heat exchanger partition 34 is in contact with the flat bottom wafer of each prismatic battery member 18, while a second opposing lower face of said heat exchange baffle 34 is directly in contact with each other. contact with the coolant.

As an alternative to the invention, each battery cell is made so that its lower edge is generally flat and free of weld bead. Thus, the lower edge of each battery cell is closer to the heat exchange partition.

According to another variant of the invention, which can advantageously be combined with the preceding variant, the contact section of the case of a battery element is perforated with orifices which allow direct contact between the exchange partition of the battery. heat and battery cells, without going through the slice of the holster. According to yet another variant, each battery cell is arranged individually in the housing, without the use of a case. Thus, the lower edge of each battery cell forms a contact wafer that is directly in contact with the heat exchange partition. In the embodiments shown in the figures, the pipe 32 of coolant is formed in the bottom 14 of the housing 12, and the partition 34 of heat exchange is interposed between the bottom 14 of the housing 12 and the battery elements, formed Here, by the cassettes 18. According to the teachings of the invention, the heat exchange partition 34 is formed by a membrane of flexible and elastically deformable material perfectly matching the edge 30 of the cassette 18 under the effect of the pressure of heat transfer fluid circulating in contact with said heat exchange partition 34. This makes it possible to guarantee that the heat exchange partition 34 is in direct contact with almost the entire surface of the contact wafer of each battery element 18, whatever the surface defects. This also makes it possible to compensate for the misalignment of the slices 30 of the cassettes 18.

The partition 34 of heat exchange is, moreover, advantageously made of an electrically insulating material heat transfer fluid 18 battery elements. Such a flexible material, elastic, electrical insulator and good heat conductor is formed by an elastomeric material, for example by silicone. To improve the heat conduction properties, without altering the other properties of the heat exchange partition 34, the addition of additives to the silicone, such as metal powder, can be provided.

Similarly, to improve the mechanical properties of the heat exchange partition 34, the silicone can be loaded with mechanical reinforcing fibers. By way of example, the heat exchange partition 34 is obtained from a mixture of aluminum powder, silicone polymer and viscous paste catalyst. This paste is injected into a flat mold in which the heat exchange partition 34 is formed by vulcanization at room temperature under the action of the catalyst. A first embodiment of the invention is shown in Figures 1 and 2. In this first embodiment of the invention, the heat transfer fluid circuit comprises at least one pipe 32 which is formed in an upper face of the rigid plate forming the bottom 14 of the housing. As represented in FIG. 2, a network of at least one heat transfer fluid pipe 32 forms a groove in the upper face of the bottom 14. In other words, the heat transfer fluid pipe 32 is etched in the upper face of the bottom. 14, the pipe 32 of heat transfer fluid being open vertically upwards. As shown in FIG. 2, the pipe 32 of the circuit forms convolutions so as to cover almost the entire surface of the bottom 14. Parallel parallel sections of the pipe are thus separated by walls 36 whose end face upper portion forms a portion of the upper face of the bottom 14. The grid 31 is supported on these walls 36 to support the weight of the cells 20.

The heat exchange partition 34 has a contour of rectangular shape complementary to that of the upper face of the bottom 14. The heat exchange partition 34 is laid flat against the upper face of the bottom 14 to cover continuously the all of said face, closing vertically upwardly each pipe 32 of fluid and covering the walls 36. Thus, the heat transfer fluid can enter the pipe 32 only through a lateral inlet orifice 38, and exit only through a hole 40 lateral exit. This thus forces the heat transfer fluid to traverse the entire line 32 between the inlet orifice 38 and the outlet orifice 40, without the possibility of interfering between the upper face of the walls 36 and the exchange partition 34 of heat, and without the possibility of escaping towards the housing of the housing 12. In variant not shown of the invention, the upper face of the bottom comprises an array of several heat transfer fluid conduits, the bottom then being equipped with a plurality of inlet and outlet ports. All pipes are closed by a common heat exchange wall which continuously covers the entire bottom.

According to another variant not shown of the invention, the bottom comprises a plurality of conduits, each conduit forming convolutions for traversing an associated portion of the upper face of the bottom, for example a rectangular portion.

Each of said top-face portions is sealingly and continuously covered by an associated complementary shape heat exchange partition of complementary shape. Each heat exchange partition is thus likely to close up the associated pipe by also covering the associated walls. In this way, the various heat exchange partitions form a tiling of the bottom of the housing. To avoid any leakage of heat transfer fluid into the housing 12 housing the battery elements 18, the periphery of the partition 34 heat exchange is sealingly attached to the bottom 14 by gluing. A bead 42 of continuous adhesive framing the heat exchange partition 34 is then interposed between the bottom 14 and the heat exchange partition 34, as shown in FIG. 3.

According to another embodiment of waterproof fastening shown in Figure 4, the partition 34 of heat exchange is fixed on the bottom plate 14 by welding. A weld bead 44 flanking the heat exchange partition 34 is formed between an edge 46 of the bottom 14 which surrounds the heat exchange partition 34 and the periphery of the heat exchange partition 34. According to yet another embodiment of leakproof fastening shown in FIG. 5, the heat exchange partition 34 is fixed to the bottom 14 by mechanical clamping between an attached frame 48 and the bottom 14 so as to grip the periphery of the partition 34 vertically. heat exchange, for example by means of clamping screws 50. During the assembly of the battery 10, the bottom 14 is first covered by its partition 34 of heat exchange. Then, the grid 31 is placed on the bottom 14 before receiving the cassettes 18 so that their lower portion 30 supports the partition 34 heat exchange against the bottom 14. The cover 16 is then placed on the cassettes 16 to allow holding cassettes 18 in position.

The mounting of such a battery is particularly easy. Indeed, the positioning and attachment of a single partition 34 heat exchange plane on the bottom 14 carrying the pipe network 32 is very fast and requires only one operation. The pipes are indeed already made rigidly directly in the bottom 14. When using the battery 10, the circuit is supplied with heat transfer fluid under pressure through the inlet port 38. The heat transfer fluid is for example injected into the pipe 32 by means of a pump. The heat transfer fluid thus travels the pipe 32 to the outlet port 40. In doing so, the heat transfer fluid under pressure elastically deforms the heat exchange partition 34 to support it vertically against the contact strips 30 of cassettes 18 located just above. The heat exchange partition 34 thus perfectly fits the surface of the lower wafer of each cassette 18, expelling the air present between the cassette 18 and the partition 34. The contact surface between the lower wafer of the cassettes 18 and the heat exchange partition 34 is thus increased, compared to a contact with a rigid partition, which promotes the exchange of heat between the heat transfer fluid and the battery cells 20. According to a second embodiment of the invention which is shown in FIG. 6, the heat transfer fluid line 32 is made in a flexible pocket 52 which is formed in a piece integral with the heat exchange partition 34. . The pocket 52 is thus made of the same material as the partition 34 of heat exchange. The pocket 52 has a generally flattened rectangular shape which is equipped with at least one side heat transfer fluid inlet port 38 and a side heat transfer fluid outlet port 40. Each orifice has a cross section smaller in size than the cross section of the pocket 52. A single pocket 52 is used to cool several adjacent cassettes 18 of a stack.

The pocket 52 is interposed between the bottom 14 of the housing and the stack of cassettes 18. For this purpose, the bottom 14 of the housing 12 has in its upper face a housing 54 for receiving the pocket 52 of heat transfer fluid. When pressurized heat transfer fluid feeds the bag 52, the bag "swells" so as to perfectly match the surface of the contact strips 30 of cassettes 18 located just above. Such a pipe 32 of heat transfer fluid is easy to position and fix in the housing 12 of the battery 10 in a single operation.

Claims (11)

REVENDICATIONS1. Motor vehicle battery (10), in particular a traction battery for an electric or hybrid vehicle, comprising: s - at least one housing (12) comprising at least one heat-transfer fluid line (32) sealed from the inside of the housing (12) by at least one heat exchange partition (34); at least one prismatic electrical energy storage element (18, 20) which is housed in the housing (12) and which is in contact with a planar wafer (30) with a planar face of said partition (34) heat exchange; characterized in that the heat exchanging partition (34) is formed by a flexible material membrane 15 perfectly matching the wafer (30) of the battery member (18, 20) under the effect of fluid pressure. coolant circulating in contact with said partition wall (34) for heat exchange. 2. Battery (10) vehicle according to the preceding claim, characterized in that it comprises a stack 20 of a plurality of battery elements (18, 20) whose contact slices (30) are arranged globally coplanar, the wafer (30) of contact of all the battery elements (18, 20) of the stack being in contact with a partition (34) common heat exchange. 25 Vehicle battery (10) according to one of the preceding claims, characterized in that the heat transfer fluid line (32) is formed in the bottom (14) of the housing (12) and the partition (34) of heat exchange is interposed between the bottom (14) of the housing (12) and the battery elements (18, 20). 30 4. Battery (10) vehicle according to any one of the preceding claims, characterized in that the conduit (32) of heat transfer fluid is formed in a face of a plate (14) which is rigidly sealed and continuous by the partition (34) of heat exchange. 5. Battery (10) vehicle according to the preceding claim, characterized in that a network of at least one pipe (32) of heat transfer fluid travels the face of the plate (14) rigid. 6. Battery (10) of a vehicle according to any one of claims 4 or 5, characterized in that the partition (34) of heat exchange is fixed on the plate (14) by gluing, a bead (42) of continuous adhesive framing the partition (34) of heat exchange. Vehicle battery (10) according to one of claims 4 or 5, characterized in that the heat exchange partition (34) is fixed to the plate (14) by welding, a cord (44) of soldering flanking the heat exchange partition (34). Vehicle battery (10) according to one of claims 4 or 5, characterized in that the heat exchange partition (34) is mechanically clamped between a frame (48) and the plate (14). . 9. Battery (10) of a vehicle according to claim 3, characterized in that the partition (34) of heat exchange is made integrally with a pocket (52) in the form of a plate in which circulates the coolant and which is arranged at the bottom (14) of the housing (12). 10. Vehicle battery (10) according to any one of the preceding claims, characterized in that each battery cell is formed by a cassette (18) which comprises two battery cells (20) which are housed in a case (26). ) which comprises the wafer (30) of contact with the wall (34) of heat exchange. 11. Battery (10) of the vehicle according to the preceding claim, characterized in that the wafer (30) of the case (26) is perforated with orifices for heat exchange by direct conduction between the cells (20) and the partition (34) for heat exchange.5