JP2019169390A - Battery module - Google Patents

Abstract

To provide a battery module that can reduce the temperature gradient of a plurality of battery cells.SOLUTION: A battery module includes a plurality of battery cells 10, a heat sink 20 having a mounting surface 40 on which the battery cells 10 are mounted, and a flow path member 30 attached to the heat sink 20 and through which a cooling water flows, and the heat sink 20 includes a first member 21 having a first mounting surface 41 that constitutes the mounting surface 40, and a second member 22 having a second mounting surface 42 that constitutes the mounting surface 40, and the first member 21 is provided with a flow path member 30, and the second member 22 is provided in a region between the first mounting surface 41 and the flow path member 30, and the second member 22 has thermal conductivity lower than that of the first member 21.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a battery module having a structure for making the temperature of a plurality of battery cells uniform.

  Hybrid vehicles and electric vehicles are equipped with a battery pack including a plurality of battery modules that serve as a power source for the motor. The battery module mounted on the electric vehicle is cooled by a cooling device because the temperature rises due to repeated charging and discharging of the battery cells as the vehicle travels (see, for example, Patent Document 1).

  Such a battery module has a structure in which a battery cell is placed on a heat sink disposed in a battery case, and a cooling pipe is attached to the heat sink. By flowing the cooling water through the cooling pipe, the battery cell is cooled via the heat sink.

  Since the temperature of each battery cell of the battery module having the above configuration is likely to decrease as it is closer to the cooling pipe, a temperature gradient is generated in the plurality of battery cells. When such a temperature gradient occurs, the battery cell far from the cooling pipe is not sufficiently cooled, and the deterioration proceeds faster than the battery cell close to the cooling pipe. Since the distance that can be traveled by the electric power charged in the battery module depends on the state of the battery cell that has been most deteriorated, it is desired to make the temperature of the plurality of battery cells uniform. Similar problems exist not only in the case of cooling but also in the case of heating the battery.

JP 2005-349955 A

  This invention is made | formed in view of such a situation, and it aims at providing the battery module which can reduce the temperature gradient of a some battery cell.

  A first aspect of the present invention that solves the above problem is that a plurality of battery cells, a heat conduction member having a placement surface on which the battery cells are placed, and a heat medium that is attached to the heat conduction member and circulates. A flow path member, and the heat conducting member includes a first member having a first placement surface that constitutes the placement surface, and a second placement surface that constitutes the placement surface. A second member having the flow path member attached to the first member, and the second member is disposed in a region between the first placement surface and the flow path member. The battery module is provided, wherein the second member has a lower thermal conductivity than the first member.

  In the first aspect, the battery cell placed on the second placement surface close to the flow path member is hardly absorbed and dissipated, and the battery cell placed on the first placement surface far from the flow path member is It is easy to absorb and dissipate heat. Therefore, the temperature difference between the battery cell close to the flow path member and the battery cell far from the flow path member is unlikely to increase. That is, the temperature gradient between battery cells can be reduced.

  According to a second aspect of the present invention, in the battery module according to the first aspect, the first member is provided with a third member on the side opposite to the first placement surface, In the battery module, the third member has a lower thermal conductivity than the first member.

  In the second aspect, heat to the battery cell can be blocked from the side opposite to the first placement surface of the heat conducting member.

  According to a third aspect of the present invention, in the battery module according to the first or second aspect, the flow path member is not attached to the second member.

  In the third aspect, the temperature difference between the battery cells placed on each of the first placement surface and the second placement surface can be further reduced.

  According to a fourth aspect of the present invention, in the battery module according to any one of the first to third aspects, the end of the battery cell on the flow path member side is within the second placement surface. It is in the battery module characterized by being located.

  In the fourth aspect, the battery cell protrudes from the second placement surface and is not in contact with the first member. According to such a configuration, the battery cell can be absorbed and radiated by the second member via the second placement surface. For this reason, it can suppress that the temperature of a battery cell falls too much and a temperature difference spreads, and can reduce the temperature difference between battery cells more reliably.

  ADVANTAGE OF THE INVENTION According to this invention, the battery module which can reduce the temperature gradient of a some battery cell is provided.

1 is an exploded perspective view of a battery module according to Embodiment 1. FIG. 3 is a side view of the battery module according to Embodiment 1. FIG. It is a figure which shows the temperature distribution of the conventional battery cell. It is a figure which shows the temperature distribution of the battery cell which concerns on Embodiment 1. FIG.

  Hereinafter, modes for carrying out the present invention will be described. In addition, description of embodiment is an illustration and this invention is not limited to the following description.

<Embodiment 1>
FIG. 1 is an exploded perspective view of the battery module, and FIG. 2 is a side view of the battery module. The battery module 1 according to the present embodiment includes a plurality of battery cells 10, a heat sink 20 that is an example of a heat conduction member, and a flow path member 30. Usually, a plurality of battery modules 1 are accommodated in a case (not shown) to form a battery pack, and the battery pack is mounted on an electric vehicle or a hybrid vehicle.

  A plurality (six in this embodiment) of battery cells 10 are arranged in parallel along one direction (X direction). Each battery cell is given a reference numeral 10a, 10b, 10c, 10d, 10e, 10f in order from the side closer to the flow path member 30. When not distinguishing the plurality of battery cells 10a to 10f, they are referred to as battery cells 10.

  Although there is no limitation in particular as the battery cell 10, For example, secondary batteries, such as a nickel-hydrogen battery and a lithium ion battery, can be used. Further, the battery cell 10 is provided with a terminal 11 at the top, and is connected in parallel or in series by a bus bar (not shown) to constitute a battery module.

  The heat sink 20 is a member on which the battery cell 10 is placed on the placement surface 40 on one side (the upper side in the Z direction in FIG. 2), and radiates and absorbs heat from the battery cell 10. In the present embodiment, the heat sink 20 is made of a rectangular flat plate member. The present invention includes a configuration in which the battery cell 10 is indirectly placed on the heat sink 20 via another member in addition to the configuration in which the battery cell 10 is directly placed on the heat sink 20. In the latter configuration, it is preferable that the intervening member has a high thermal conductivity (for example, equal to or higher than the thermal conductivity of the heat sink 20).

  The flow path member 30 is a tubular member through which cooling water flows as a heat medium. Although not particularly illustrated, the entire flow path member 30 is provided in a ring shape across the plurality of battery modules 1. In other words, the heat sink 20 of each battery module 1 is attached to a part of the annular flow path member 30. In the present embodiment, the flow path member 30 is attached along one side of the heat sink 20 (one side in the Y direction perpendicular to the X direction in which the battery cells 10 are arranged in parallel).

  Although not particularly shown, the flow path member 30 is provided with devices such as a radiator and a pump. With such a configuration, the cooling water cooled by the radiator is circulated through the flow path member 30 and cooled again by the radiator. The radiator, the pump, and the like are accommodated in a battery module case.

  The heat sink 20 includes a first member 21, a second member 22, and a third member 23. The first member 21, the second member 22, and the third member 23 are all formed of a rectangular flat plate member.

  The first member 21 has such a size that six battery cells 10 can be placed in a plan view viewed from the Z direction. A part of the surface of the first member 21 (the surface on which the battery cell 10 is placed) is a first placement surface 41. The first member 21 includes a recess 24 in which the second member 22 is provided between the first placement surface 41 and the flow path member 30.

  The second member 22 is provided in the recess 24 which is a region between the first placement surface 41 and the flow path member 30 in the surface of the first member 21. Specifically, the second member 22 has an outer shape that matches the opening shape of the recess 24, and has substantially the same thickness as the depth of the recess 24. Such a second member 22 is fitted in the recess 24.

  In the present embodiment, the entire surface of the second member 22 is the second placement surface 42. The second placement surface 42 is substantially flush with the first placement surface 41. The first mounting surface 41 and the second mounting surface 42 constitute a substantially flush mounting surface 40. The battery cell 10 is placed on the placement surface 40 so as not to straddle the first placement surface 41 and the second placement surface 42. Here, three battery cells 10 are placed on each of the first placement surface 41 and the second placement surface 42.

  The second member 22 has a lower thermal conductivity than the first member 21. In the present embodiment, the second member 22 is made of aluminum, and the first member 21 is made of copper. Of course, these members may be made of different materials. As materials for the first member 21 and the second member 22, in addition to aluminum and copper, metal materials such as iron and stainless steel, and oxides such as copper oxide and iron oxide can be used.

  The third member 23 is provided on the back surface (the surface opposite to the first placement surface 41) of the first member 21. In the present embodiment, the third member 23 has substantially the same outer shape as the first member 21. The third member 23 is made of a material having a lower thermal conductivity than that of the first member 21. Since the third member 23 is provided on the back surface of the first member 21, heat from the back surface side to the battery cell 10 can be blocked. The material of the third member 23 is not particularly limited, and a metal material, a metal oxide, a resin material, or the like can be used.

  The manufacturing method of the heat sink 20 including the first member 21, the second member 22, and the third member 23 is not described in detail because a known method can be applied. As an example, a concave portion 24 is provided in a flat copper plate to form the first member 21, and a second member 22 made of aluminum is joined to the concave portion 24 by welding. Furthermore, the heat sink 20 can be manufactured by adhering the third member 23 made of resin to the back surface of the first member 21 with an adhesive, or by fixing with a fastening means such as a bolt or a rivet.

  In the battery module 1 having the above-described configuration, in the plan view of the heat sink 20, the first placement surface 41 is separated from the flow path member 30 by the second placement surface 42. (Or in a cross-sectional view), the flow path member 30 is connected. Further, the second mounting surface 42 is not directly connected to the flow path member 30.

  With such a configuration, the battery cell 10 placed on the first placement surface 41 is radiated and absorbed by the cooling water of the flow path member 30 via the first member 21. On the other hand, the battery cell 10 placed on the second placement surface 42 is radiated and absorbed by the cooling water of the flow path member 30 via the second member 22 and the first member 21.

  As described above, the first member 21 has a higher thermal conductivity than the second member 22 and is directly attached to the flow path member 30. Further, the second member 22 has a lower thermal conductivity than the first member 21 and is not directly attached to the flow path member 30. That is, the battery cell 10 placed on the first placement surface 41 is more easily absorbed and radiated than the battery cell 10 placed on the second placement surface 42. Such a heat sink 20 can reduce a temperature difference (temperature gradient) between the battery cells 10.

  A mechanism that can reduce the temperature gradient of the battery cell 10 will be described with reference to FIGS. 3 and 4. FIG. 3 is a diagram showing a temperature distribution of a conventional battery cell, and FIG. 4 is a diagram showing a temperature distribution of the battery cell. In any of the figures, the horizontal axis represents the distance from the flow path member of each battery cell 10a to 10f, and the vertical axis represents the temperature of each battery cell 10a to 10f.

  First, a temperature gradient in a heat sink made of one member having thermal conductivity will be described with reference to FIG. Such a conventional heat sink has a uniform thermal conductivity. When such a heat sink is used, the temperature of the battery cell 10 closer to the flow path member 30 is more likely to decrease, and the temperature of the battery cell 10 farther from the flow path member 30 is less likely to decrease. That is, the temperature difference between the battery cell 10 close to the flow path member 30 and the battery cell 10 far from the flow path member 30 tends to increase.

  In the case of using a conventional heat sink made of one member, the temperatures of the battery cells 10a to 10f are Ta 'to Tf', respectively. A temperature difference between the temperature Ta ′ of the lowest battery cell 10a and the temperature Tf ′ of the highest battery cell 10f is defined as a temperature gradient TΔ ′.

  On the other hand, as shown in FIG. 4, in the heat sink 20 of the present invention, the battery cells 10 a to 10 c placed on the second placement surface 42 close to the flow path member 30 are difficult to absorb and dissipate heat, and the flow path member 30. The battery cells 10d to 10f placed on the first placement surface 41 far from the surface are likely to absorb heat and dissipate heat. Therefore, the temperature difference between the battery cells 10 a to 10 c close to the flow path member 30 and the battery cells 10 d to 10 f far from the flow path member 30 is difficult to increase.

  When the heat sink 20 of the present invention is used, the temperatures of the battery cells 10a to 10f are Ta to Tf, respectively. A temperature difference between the temperature Ta of the lowest battery cell 10a and the temperature Tf of the highest battery cell 10f is defined as a temperature gradient TΔ. According to the battery module 1 using such a heat sink 20, the temperature gradient TΔ between the battery cells 10 can be reduced more than the temperature gradient TΔ ′ between the battery cells 10 when a conventional heat sink is used.

  In the battery module 1 of the present embodiment, the flow path member 30 is not directly attached to the second member 22. For this reason, it can be set as the structure which is hard to absorb heat and to heat radiation rather than the structure which attaches the flow-path member 30 to the 2nd member 22 directly. Thereby, as above-mentioned, the temperature difference between the battery cells 10 mounted in each of the 1st mounting surface 41 and the 2nd mounting surface 42 can be reduced further.

  In the present invention, the second member 22 may be directly attached to the flow path member 30. In other words, the second member 22 provided on the surface of the first member 21 may be configured to contact the flow path member 30. Even in such a configuration, the second member 22 has a lower thermal conductivity than the first member 21, and thus exhibits the effect of reducing the temperature difference described above.

  Further, in the battery module 1 of the present embodiment, the end portion 12 (see FIG. 2) on the flow path member 30 side of the battery cell 10 a is located in the second placement surface 42. In other words, the battery cell 10 a protrudes from the second placement surface 42 and is not in contact with the first member 21. According to such a configuration, the battery cell 10 a can be absorbed and radiated by the second member 22 via the second placement surface 42. For this reason, it can suppress that the temperature of the battery cell 10a falls too much and a temperature difference spreads, and can reduce the temperature difference between the battery cells 10 mentioned above more reliably.

  In the present invention, the end 12 of the battery cell 10 a may protrude from the second placement surface 42 and contact the first member 21.

<Other embodiments>
Although the embodiments of the present invention have been described, of course, the present invention is not limited to the above-described embodiments, and additions, omissions, substitutions, and the like of configurations may be made without departing from the spirit of the present invention. Other changes are possible.

  In each said embodiment, although it was the structure which distribute | circulates cooling water to the flow-path member 30, it is not limited to this. The heat medium may be a fluid, and air may be used in addition to water. Moreover, in each said embodiment, although the cooling water was used in order to absorb and radiate heat from the battery cell 10, you may distribute | circulate the heat medium for heating the battery cell 10 to the flow path member 30. FIG. The present invention can also be applied to heat the battery cell 10 with such a heat medium and maintain it at a predetermined temperature.

  In the first embodiment, the first placement surface 41 and the second placement surface 42 are substantially flush, but the present invention is not limited to this. That is, the heights in the Z direction of the first placement surface 41 and the second placement surface 42 may be different. In this case, a member having good thermal conductivity that fills the gap between the battery cell 10 and the first placement surface 41 or the second placement surface 42 may be interposed.

  In the first embodiment, the battery cell 10 is disposed so as not to straddle the first placement surface 41 and the second placement surface 42, but is not limited thereto. You may arrange | position the battery cell 10 so that the 1st mounting surface 41 and the 2nd mounting surface 42 may be straddled. In this case, the temperature gradient in one battery cell 10 can be reduced.

DESCRIPTION OF SYMBOLS 1 ... Battery module 10, 10a-10f ... Battery cell, 20 ... Heat sink (heat conduction member), 21 ... 1st member, 22 ... 2nd member, 23 ... 3rd member, 30 ... Channel member, 40 ... placement surface, 41 ... first placement surface, 42 ... second placement surface

Claims (4)

A plurality of battery cells;
A heat conducting member having a mounting surface on which the battery cell is mounted;
A flow path member that is attached to the heat conducting member and through which the heat medium flows, and
The heat conductive member includes a first member having a first placement surface that constitutes the placement surface, and a second member having a second placement surface that constitutes the placement surface. ,
The flow path member is attached to the first member, and the second member is provided in a region between the first placement surface and the flow path member,
The battery module, wherein the second member has a thermal conductivity lower than that of the first member. The battery module according to claim 1,
The first member is provided with a third member on the side opposite to the first placement surface,
The battery module, wherein the third member has a lower thermal conductivity than the first member. The battery module according to claim 1 or 2,
The battery module, wherein the flow path member is not attached to the second member. In the battery module according to any one of claims 1 to 3,
An end of the battery cell on the flow path member side is located in the second placement surface. The battery module.

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