JP2021051883A - Battery unit - Google Patents

Abstract

To provide a battery unit capable of appropriately cooling a battery block.SOLUTION: A battery unit comprises: a battery block 30 in which a plurality of battery cells 31 are aligned; and a cooler 40 which is provided in a manner facing each of the plurality of battery cells 31, and which has a coolant passage 41 for flowing a coolant in a direction traversing the plurality of battery cells 31. The coolant passage 41 is provided in such a manner that a passage cross-sectional area may vary in a coolant circulation direction. In a passage region traversing a battery cell 31C with a lower air cooling degree, the passage cross-sectional area is smaller than that in passage regions traversing battery cells 31A and 31B with a higher air cooling degree.SELECTED DRAWING: Figure 2

Description

The present invention relates to a battery unit.

In order to increase the capacity of the storage battery, a plurality of battery cells are connected in series or in parallel to form a battery unit. In such a battery unit, in order to prevent each battery cell from becoming excessively high temperature, a cooler is provided in a state of being in contact with each battery cell, and each battery cell is cooled by this cooler. For example, the assembled battery of Patent Document 1 is provided with a cooler for cooling the assembled battery. On the outward path side and the return path side of the cooling passage provided in the cooler, the temperature of the refrigerant on the return path side rises due to heat reception, so that the outward path side is more likely to be cooled than the return path side. In order to adjust the cooling difference between the outward path and the return path, an electronic component that generates heat is provided near the storage battery on the outward path side.

Japanese Unexamined Patent Publication No. 2010-15788

By the way, in each battery cell, air cooling is performed by heat dissipation from the outer surface to the atmosphere. In the battery block in which the battery cells are arranged, the amount of heat radiated by the air cooling is different between the inner battery cell and the outer battery cell. Therefore, the temperature of the battery cell is lower toward the outside and the temperature of the battery cell is higher toward the inside. If there is such a variation in temperature within the battery block, deterioration due to temperature and difference in characteristics due to temperature occur, which is not desirable.

The present invention has been made in view of the above problems, and a main object thereof is to provide a battery unit capable of appropriately cooling a battery block.

The first means is a cooler having a battery block provided by arranging a plurality of battery cells and a refrigerant passage provided in a state of facing each of the plurality of battery cells and flowing a refrigerant in a direction crossing the plurality of battery cells. The refrigerant passages are provided so as to have different passage cross-sectional areas in the refrigerant flow direction, and cross a battery cell having a large degree of air cooling in a passage region that crosses a battery cell having a small degree of air cooling. The passage cross-sectional area is smaller than the passage area.

In the cooler of the battery unit, the refrigerant passages are provided so that the passage cross-sectional area differs depending on the refrigerant flow direction, and in the passage region that crosses the battery cell with a small degree of air cooling, it crosses the battery cell with a large degree of air cooling. The passage cross-sectional area is smaller than the passage area. As a result, the speed of the refrigerant in the passage region crossing the battery cell having a small degree of air cooling becomes faster than the speed of the refrigerant in the passage region crossing the battery cell having a high degree of air cooling, and in the battery cell having a small degree of air cooling. , Heat dissipation to the cooler is promoted as compared with a battery cell having a large degree of air cooling. That is, by increasing the amount of heat radiated from the battery cell having a small degree of air cooling to the cooler, it is possible to suppress the variation in the temperature of each battery cell.

The second means is that in the refrigerant passage, the passage cross-sectional area is reduced at the intermediate portion between the passage inlet and the passage outlet.

In a battery block in which a plurality of battery cells are arranged, the degree of air cooling is small in the battery cells in the middle portion in the direction in which the battery cells are arranged, that is, in the refrigerant flow direction, and heat tends to be trapped. Therefore, the cross-sectional area of the passage is small in the middle part of the refrigerant passage in which the battery cells in the middle part come into contact with each other. This promotes heat dissipation to the cooler in the battery cell in the middle portion where the degree of air cooling is small and heat tends to be trapped. Therefore, by increasing the amount of heat radiated to the cooler in the battery cells in the intermediate portion, it is possible to suppress variations in the temperature of each battery cell.

The third means is that the cooler has a first wall portion on the battery block side and a second wall portion facing the first wall portion, and the refrigerant passage is formed between them. The second wall portion is provided with a protruding portion that projects toward the first wall portion, and the projecting portion narrows the cross-sectional area of the passage.

Of the first wall portion and the second wall portion provided across the refrigerant passage, a protrusion is provided on the second wall portion, and the passage cross-sectional area is narrowed by this protrusion. As a result, in the refrigerant passage, the refrigerant flows on the first wall side, that is, on the battery block side due to the protrusion provided on the second wall side. Therefore, in each battery cell, it is possible to have a difference in the refrigerant effect in each battery cell while keeping the distance between the refrigerant passage and the cell end face the same.

In the fourth means, the passage cross-sectional area is narrowed in the direction orthogonal to the refrigerant flow direction in the facing surface facing the plurality of battery cells.

The refrigerant passage has a narrow passage cross-sectional area in the direction orthogonal to the refrigerant flow direction in the facing surface facing the plurality of battery cells. As a result, the passage cross-sectional area can be made different even when the passage cross-sectional area cannot be narrowed in the direction across the plurality of battery cells.

Fifth means, the cooler has a cross-sectional area variable member that makes the passage cross-sectional area of the refrigerant passage variable, and the cross-sectional area variable member is deformable according to temperature, and the high temperature battery. It is deformed so that the passage cross-sectional area of the passage region corresponding to the cell is narrow and the passage cross-sectional area of the passage region corresponding to the low temperature battery cell is wide.

If the passage cross-sectional area is different in the refrigerant flow direction, there is a concern of pressure loss in a place where the passage cross-sectional area becomes narrow. Further, when the current flowing through the battery unit is small, the amount of heat generated by each battery cell is small, and a temperature difference between the battery cells due to air cooling is unlikely to occur. In such a case, it is not necessary to change the heat dissipation to the cooler depending on the location.

Therefore, the cooler is provided with a cross-sectional area variable member that makes the passage cross-sectional area of the refrigerant passage variable. The variable cross-sectional area member is deformed so that the passage cross-sectional area of the passage region corresponding to the high-temperature battery cell is narrow and the passage cross-sectional area of the passage region corresponding to the low-temperature battery cell is wide. As a result, in a state where a temperature difference occurs between the battery cells, the passage cross-sectional area of the passage region corresponding to the battery cells in which the degree of air cooling is small and the temperature of the battery cells is high becomes relatively narrow. On the other hand, when there is no temperature difference, that is, when a high temperature battery cell does not occur, all the battery cells become low temperature in the refrigerant flow direction, and the passage cross-sectional area does not change in the refrigerant flow direction. Therefore, it is possible to balance the necessity of changing the speed of the refrigerant and the pressure loss.

The sixth means includes a plurality of battery modules having the battery block and the cooler, and the plurality of battery modules are configured such that the refrigerant passages of the respective coolers are connected in series. The average passage cross-sectional area of the battery module on the upstream side of the plurality of battery modules is larger than the average passage cross-sectional area of the battery module on the downstream side of the plurality of battery modules.

When the refrigerant passages of the plurality of battery modules are connected in series, the temperature of the refrigerant in the battery module on the downstream side rises as compared with the battery module on the upstream side, and the cooling efficiency decreases. Therefore, the average passage cross-sectional area of the battery module on the upstream side is made larger than the average passage cross-sectional area of the battery module on the downstream side. As a result, the average speed of the refrigerant in the battery module on the downstream side becomes faster than the average speed of the battery module on the upstream side. Therefore, the temperature variation between the battery modules can be suppressed.

The seventh means includes a plurality of battery modules having the battery block and the cooler, and the plurality of battery modules are configured such that the refrigerant passages of the respective coolers are connected in series. The dimension in the refrigerant flow direction of the region where the passage cross-sectional area of the battery module on the upstream side of the plurality of battery modules is small is the passage cross-sectional area of the battery module on the downstream side of the plurality of battery modules. Is smaller than the dimension in the refrigerant flow direction in the region where is small.

When the refrigerant passages of the plurality of battery modules are connected in series, the temperature of the refrigerant in the battery module on the downstream side rises as compared with the battery module on the upstream side, and the cooling efficiency decreases. Therefore, the dimension in the refrigerant flow direction in the region where the passage cross-sectional area of the battery module on the upstream side is small is made smaller than the dimension in the refrigerant flow direction in the region where the passage cross-sectional area of the battery module on the downstream side is small. is there. As a result, the region where the heat radiation of the battery module on the downstream side to the refrigerant becomes large becomes longer than that of the battery module on the upstream side. Therefore, the temperature variation between the battery modules can be suppressed.

Schematic configuration of the battery unit Schematic configuration of the battery module The figure which shows the heat dissipation state in the conventional battery module The figure which shows the refrigerant rate in the battery module of this embodiment The figure which shows the heat dissipation state in the battery module of this embodiment Schematic configuration of the battery module in another embodiment Schematic configuration of the battery module in another embodiment Schematic configuration of the battery module in another embodiment Schematic configuration of the battery module in another embodiment Schematic configuration of the battery module in another embodiment Schematic configuration of the battery module in another embodiment

<Embodiment>
Hereinafter, embodiments embodying the present invention will be described with reference to the drawings. In the present embodiment, for example, in a vehicle traveling by using a motor such as an electric vehicle or a PHV or HV as a drive source, the battery unit is embodied as an in-vehicle power source that supplies electric power to various devices such as the motor of the vehicle. There is. In addition, it may be embodied as a battery unit which is an in-vehicle power source of a vehicle traveling by using an engine as a drive source. Further, in the following description, the upper side of FIG. 2, that is, the battery block 30 side is the upper side, and the lower side of FIG. 2, that is, the cooler 40 side is the lower side. Further, the left side of FIG. 2, that is, the upstream side in the direction in which the refrigerant flows is the front side, and the right side of FIG. 2, that is, the downstream side is the rear side. Then, the direction orthogonal to the vertical direction and the front-back direction is defined as the width direction.

FIG. 1 is a schematic configuration diagram of the battery unit 10. The battery unit 10 has a plurality of battery modules 20. Each battery module 20 includes a battery block 30 in which a plurality of battery cells 31 are arranged side by side, and a cooler 40 provided in contact with the plurality of battery cells 31.

The plurality of battery modules 20 are configured so that the refrigerant passages 41 in the cooler 40 of each battery module 20 are connected in series. Then, the rows of the plurality of battery modules 20 in which the refrigerant passages 41 are connected in series are arranged so as to be parallel to each other. Further, the refrigerant passage 41 is supplied with the refrigerant from the cooling mechanism 60.

The cooling mechanism 60 includes a circulation pump 61 that circulates the refrigerant and a heat radiating unit 62 that dissipates heat from the refrigerant. The circulation pump 61 circulates cooling water, which is a refrigerant, in a circulation path including a refrigerant passage 41 and a heat radiating portion 62 in the cooler 40. The heat radiating unit 62 is, for example, a radiator or a chiller that dissipates heat from the refrigerant by a fan. The refrigerant may be a fluid such as a liquid or a gas.

The circulation pump 61 and the heat radiating unit 62 are controlled and driven by the control device 70. The control device 70 is composed of a microcomputer including a CPU, a ROM, a RAM, an input / output interface, and the like. Further, the control device 70 is connected to a higher-level ECU or the like, which is a higher-level control device. The control device 70 is connected to a host ECU or the like by a communication network such as CAN so that it can communicate with each other, and various data can be shared with each other.

The control device 70 drives the circulation pump 61 and the heat radiating unit 62 based on the temperature of the battery cell 31 detected by the temperature sensor 71 provided on the surface of the battery cell 31. It is desirable that the temperature sensor 71 is provided in each battery module 20. Further, the circulation pump 61 and the heat radiating unit 62 may be driven based on not only the temperature of the battery cell 31 detected by the temperature sensor 71 but also the charge current and the discharge current of the battery unit 10.

The battery block 30 is composed of a plurality of battery cells 31. Each battery cell 31 is a secondary battery such as a lithium ion storage battery. Each battery cell 31 constitutes a battery block 30 by arranging a plurality of the battery cells 31 (six in the present embodiment) in the stacking direction, that is, in the front-rear direction. Further, each battery cell 31 has a rectangular parallelepiped shape having a thin thickness in the front-rear direction. Each battery cell 31 is provided with a terminal 32 on the upper surface thereof. Each battery cell 31 has its terminal 32 connected in series or in parallel to an adjacent battery cell 31. The battery cell 31 may have a cylindrical shape instead of a rectangular parallelepiped shape.

A cooler 40 is provided under the battery block 30 in a state of facing each of the plurality of battery cells 31. That is, the cooler 40 is in contact with the lower surface of the battery block 30. It should be noted that each battery cell 31 does not have to be in direct contact with the cooler 40. In this case, it is sufficient that heat can be transferred from each battery cell 31 to the cooler 40. That is, each battery cell 31 and the cooler 40 need only be in thermal contact with each other.

The cooler 40 has a refrigerant passage 41 for flowing a refrigerant in a direction across the plurality of battery cells 31, that is, in a front-rear direction. The refrigerant passages 41 of each battery module 20 are connected in series to the refrigerant passages 41 of the battery modules 20 adjacent to each other in the front-rear direction via a pipe 42. The connecting pipe 42 connects the refrigerant passages 41 of the coolers 40 adjacent to each other in the front-rear direction. The connecting pipe 42 has the same width as the cooler 40 at the connecting portion with the refrigerant passage 41, and the passage is narrowed once in the middle and expanded to the width of the refrigerant passage 41 again. The connecting pipe 42 may have the same width as the cooler 40 over its entire length.

FIG. 2 is a schematic cross-sectional view of the battery module 20. The cooler 40 of the battery module 20 is made of metal such as aluminum and has a hollow square cylinder shape that opens in the front-rear direction. The cooler 40 has a first wall portion 51 on the upper side (battery block 30 side) and a second wall portion 52 on the lower side facing the first wall portion 51, and a hollow portion between them is formed. It is a refrigerant passage 41 through which the refrigerant flows. The widthwise dimension of the cooler 40 is the same as or slightly larger than the widthwise dimension of the battery block 30. Further, the dimensions of the cooler 40 in the front-rear direction are the same as or slightly larger than the dimensions of the battery block 30 in the front-rear direction. That is, the upper surface of the cooler 40 in contact with the battery block 30 is larger than the lower surface of the battery block 30. As a result, the lower surface of each battery cell 31 comes into contact with the cooler 40 on the entire surface.

A connecting portion 43 for connecting the connecting pipe 42 is provided at the front end portion (passage inlet 53 side) and the rear end portion (passage outlet 54 side) of the cooler 40. The connecting portion 43 is adapted to enter the inside of the connecting pipe 42. The connecting portion 43 may cover the outside of the connecting pipe 42, and the connecting pipe 42 may enter the inside of the connecting portion 43.

In the refrigerant passage 41, the passage cross-sectional area is narrow (small) at the intermediate portion 55 between the passage inlet 53 and the passage outlet 54. In the intermediate portion 55 of the refrigerant passage 41, a protruding portion 56 is provided on the second wall portion 52. By providing the protruding portion 56, the passage cross-sectional area of the intermediate portion 55 of the refrigerant passage 41 is narrowed. As a result, in the refrigerant passage 41, the refrigerant flows on the first wall portion 51 side, that is, on the battery block 30 side by the protruding portion 56 provided on the second wall portion 52 side. The passage cross-sectional area is the area of the surface orthogonal to the flow direction (front-back direction) of the refrigerant.

The protruding portion 56 has a protruding dimension that increases toward the center of the refrigerant passage 41. Specifically, the protruding portion 56 is provided over the entire width direction, so that the protruding amount gradually increases toward the downstream side and the protruding amount gradually decreases after exceeding the top. It has an arcuate protruding shape. The surface of the protrusion 56 on the refrigerant passage 41 side is a curved surface. The front-rear dimension L1 of the protrusion 56 is smaller than the front-rear dimension of the battery block 30. Specifically, it is desirable that the protruding portion 56 is not provided in a certain area of the battery cell 31A at the front end and the battery cell 31B at the rear end of the battery block 30. Further, it is desirable that the maximum protruding dimension H1 of the protruding portion 56 is such that the pressure loss does not become too large.

Next, the effect when the protruding portion 56 is provided as in the present embodiment will be described. FIG. 3 is a diagram showing a heat dissipation state in a conventional battery module. The arrows in FIG. 3 indicate how heat is transferred, and the larger the arrow, the larger the amount of heat dissipated from the conventional battery module.

The conventional battery module is different from the present embodiment in that the cooler C is not provided with a protrusion and the passage cross-sectional area of the refrigerant passage is the same over the entire length in the front-rear direction. Regarding the configuration of the battery block 30 and the like, the conventional battery module is the same as that of the present embodiment.

When a current flows through the battery block 30 during charging or discharging, the temperature of each battery cell 31 rises. When the temperature of each battery cell 31 rises and a difference occurs between the ambient (atmosphere) temperature and the temperature of the battery cell 31, heat is dissipated from each battery cell 31 to the atmosphere. At this time, in the battery cell 31A at the front end, heat can be dissipated from the outer surface on the front side thereof. Similarly, the battery cell 31B at the rear end can also dissipate heat from the outer surface on the rear side. That is, the outer (front end and rear end) battery cells 31A and 31B have a higher degree of air cooling than the other battery cells 31. Then, the battery cells 31 adjacent to the outer battery cells 31A and 31B transfer heat to the outer battery cells 31A and 31B, and the temperature thereof drops to some extent. That is, due to heat dissipation to the atmosphere, the temperature of the battery cell 31 outside the battery block 30 is the lowest, and the temperature of the battery cell 31C in the middle portion is the highest. In the following description, the degree of heat dissipation to the atmosphere (air cooling) and the degree of heat transfer to adjacent cells due to air cooling are combined to determine the degree of air cooling.

On the other hand, each battery cell 31 is in contact with the cooler C in the same manner. Further, there is no difference in heat dissipation conditions such as speed in the refrigerant passage of the cooler C. Therefore, the amount of heat radiated from each battery cell 31 to the cooler C is almost the same.

Therefore, conventionally, the difference in the degree of air cooling of each battery cell 31 directly becomes the difference in the amount of heat radiated from each battery cell 31. Since the amount of heat radiated from each battery cell 31 is different, the temperature of each battery cell 31 is different. Specifically, the temperature of the battery cell 31C in the middle portion is high, and the temperature of the outer battery cells 31A and 31B is low. Then, since the current is limited according to the battery cell 31C in the intermediate portion where the temperature is high, the charging current and the discharging current of the entire battery module are limited. Further, the battery cell 31C in the intermediate portion has a high temperature, so that deterioration is accelerated. Since the usage range of the battery block 30 is determined according to the deterioration of the battery cell 31C in the intermediate portion, the usage range of all the battery cells 31 is narrowed.

On the other hand, in the present embodiment, the passage cross-sectional area in the refrigerant passage 41 is narrowed at the intermediate portion 55. FIG. 4 is a diagram showing the refrigerant speed in the refrigerant passage 41 of the present embodiment. The arrow in FIG. 4 indicates the speed of the refrigerant, and the larger the size, the faster the speed of the refrigerant.

In the present embodiment, since the passage cross-sectional area of the refrigerant passage 41 differs depending on the location, the speed of the refrigerant in the refrigerant passage 41 differs depending on the location. That is, in the refrigerant passage 41, the speed of the refrigerant changes depending on the location. Specifically, the narrower the cross-sectional area of the passage, the faster the speed of the refrigerant. In the intermediate portion 55 having a narrow passage cross-sectional area, the speed of the refrigerant is higher than that in the vicinity of the passage inlet 53 and the passage outlet 54 having a wide passage cross-sectional area.

FIG. 5 is a diagram showing a heat dissipation state in the battery module 20 of the present embodiment. Similar to the arrow of FIG. 3, the arrow of FIG. 5 indicates how heat is transferred, and the larger the arrow, the larger the amount of heat dissipated from the conventional battery module 20.

When a current flows through the battery block 30 during charging or discharging, the temperature of each battery cell 31 rises. When the temperature of each battery cell 31 rises and a difference occurs between the ambient (atmosphere) temperature and the temperature of the battery cell 31, heat is dissipated from each battery cell 31 to the atmosphere. At this time, as in the conventional case, the outer battery cells 31A and 31B have a higher degree of air cooling than the other battery cells 31. Therefore, heat is dissipated toward the outside of the battery block 30, and the heat is most stored in the battery cell 31C in the middle portion.

On the other hand, the amount of heat radiated from each battery cell 31 to the cooler 40 differs depending on the location because the passage cross-sectional area of the refrigerant passage 41 differs depending on the location. Specifically, the smaller the passage cross-sectional area and the faster the speed of the refrigerant, the larger the amount of heat dissipated to the refrigerant. Therefore, the amount of heat radiated from the battery cell 31C in the intermediate portion corresponding to the region where the passage cross-sectional area is narrow to the cooler 40 is promoted. Further, although the passage cross-sectional area is narrowed by the protruding portion 56, the protruding portion 56 is provided on the second wall portion 52 side and does not hinder heat dissipation from each battery cell 31 to the refrigerant. That is, since the projecting portion 56 is provided on the second wall portion 52 side, in each battery cell 31, each battery cell 31 has the same separation distance between the refrigerant passage 41 and the cell end surface (lower surface). It is possible to have a difference in the refrigerant effect.

Therefore, the amount of heat radiated to the cooler 40 is larger in the battery cell 31C in the middle portion where the degree of air cooling is smaller than in the outer battery cells 31A and 31B where the degree of air cooling is large. That is, the speed of the refrigerant in the passage region across the battery cell 31 (battery cell 31C in the middle portion) having a small degree of air cooling crosses the battery cell 31 (outer battery cells 31A, 31B) having a high degree of air cooling. Faster than the rate of refrigerant in the region. Then, in the battery cell 31C in the intermediate portion, heat dissipation to the cooler 40 is promoted as compared with the outer battery cells 31A and 31B.

Further, the difference in the degree of air cooling between the outer battery cells 31A and 31B and the intermediate battery cell 31C is the difference in the amount of heat radiated to the cooler 40 between the outer battery cells 31A and 31B and the intermediate battery cell 31C. It is desirable that it is about the same as. As a result, the total of the degree of air cooling and the amount of heat radiated to the cooler 40 becomes about the same between the battery cells 31. Therefore, the temperature of each battery cell 31 is equalized, and it is possible to prevent the current and the range of use from being limited by some of the high temperature battery cells 31.

When the refrigerant passages 41 of the plurality of battery modules 20 are connected in series as in the present embodiment, the temperature of the refrigerant of the battery module 20 on the downstream side rises as compared with the battery module 20 on the upstream side. .. Therefore, the temperature difference between the battery block 30 and the refrigerant becomes small, and the cooling efficiency on the downstream side is lower than that on the upstream side.

Therefore, it is desirable that the average passage cross-sectional area of the refrigerant passage 41 of the battery module 20 on the upstream side is larger than the average passage cross-sectional area of the refrigerant passage 41 of the battery module 20 on the downstream side. Specifically, the maximum protrusion dimension H1 of the protrusion 56 is smaller on the upstream side than on the downstream side. As a result, the average speed of the refrigerant in the battery module 20 on the downstream side becomes faster than the average speed of the battery module 20 on the upstream side. Therefore, the temperatures of the battery module 20 on the upstream side and the battery module 20 on the downstream side can be made about the same. Further, even if the temperature of the refrigerant rises and the cooling efficiency decreases, the difference in heat dissipation efficiency to the cooler 40 can be secured by increasing the maximum protruding dimension H1 of the protruding portion 56, and the inside of the battery module 20 on the downstream side can be secured. The temperature difference can be reduced. The passage cross-sectional area of the battery module 20 on the downstream side may be smaller than the passage cross-sectional area of the refrigerant passage 41 of the battery module 20 on the upstream side as a whole. That is, the passage cross-sectional area at the location corresponding to the same position of the refrigerant passage 41 may be smaller on the downstream side than on the upstream side.

Further, the dimension L1 in the front-rear direction of the region where the passage cross-sectional area of the battery module 20 is small is the front-rear direction of the region where the passage cross-sectional area of the battery module 20 on the downstream side of the plurality of battery modules 20 is small. It is desirable that the size is smaller than L1. Specifically, the dimension L1 in the front-rear direction of the region where the protrusion 56 is provided is smaller on the upstream side than on the downstream side. As a result, the region where the heat radiation of the battery module 20 on the downstream side to the refrigerant becomes large becomes longer than that of the battery module 20 on the upstream side. Therefore, the temperatures of the battery module 20 on the upstream side and the battery module 20 on the downstream side can be made about the same.

According to the present embodiment described in detail above, the following excellent effects can be obtained.

In the cooler 40 of the battery unit 10, the refrigerant passage 41 is provided so that the passage cross-sectional area differs depending on the refrigerant flow direction (front-rear direction), and air is provided in the passage region crossing the battery cell 31 where the degree of air cooling is small. The passage cross-sectional area is smaller than the passage region that crosses the battery cell 31 having a large degree of cooling. As a result, the amount of heat radiated from the battery cell 31 having a small degree of air cooling to the cooler 40 increases, so that the temperature variation of each battery cell 31 can be suppressed.

Heat dissipation to the cooler 40 in the battery cell 31C in the middle portion where the degree of air cooling is small and heat tends to be trapped is promoted. Therefore, the amount of heat radiated to the cooler 40 in the battery cell 31C in the intermediate portion increases, so that the temperature variation of each battery cell 31 can be suppressed.

In the refrigerant passage 41, the protruding portion 56 provided on the second wall portion 52 side allows the refrigerant to flow on the first wall portion 51 side, that is, on the battery block 30 side. Therefore, in each battery cell 31, it is possible to have a difference in the refrigerant effect in each battery cell 31 while keeping the distance between the refrigerant passage 41 and the cell end face the same.

When the refrigerant passages 41 of the plurality of battery modules 20 are connected in series, the temperature of the refrigerant in the battery module 20 on the downstream side rises as compared with the battery module 20 on the upstream side, and the cooling efficiency decreases. Therefore, the average passage cross-sectional area of the battery module 20 on the upstream side is made larger than the average passage cross-sectional area of the battery module 20 on the downstream side. As a result, the average speed of the refrigerant in the battery module 20 on the downstream side becomes faster than the average speed of the battery module 20 on the upstream side. Therefore, the temperature variation between the battery modules 20 can be suppressed.

When the refrigerant passages 41 of the plurality of battery modules 20 are connected in series, the temperature of the refrigerant in the battery module 20 on the downstream side rises as compared with the battery module 20 on the upstream side, and the cooling efficiency decreases. Therefore, the dimension L1 in the front-rear direction of the region where the passage cross-sectional area of the battery module 20 on the upstream side is small is smaller than the dimension L1 in the front-rear direction of the region where the passage cross-sectional area of the battery module 20 on the downstream side is small. It is done. As a result, the region where the heat radiation of the battery module 20 on the downstream side to the refrigerant becomes large becomes longer than that of the battery module 20 on the upstream side. Therefore, the temperature variation between the battery modules 20 can be suppressed.

<Other Embodiments>
The present invention is not limited to the above embodiment, and may be implemented as follows, for example. Incidentally, the configuration of the following alternative example may be applied individually to the configuration of the above embodiment, or may be applied in any combination.

FIG. 6 is a schematic configuration diagram of the battery module 120 in another embodiment. In FIG. 6, the passage cross-sectional area is changed by the cross-sectional area variable member 156. If the passage cross-sectional area is different in the front-rear direction, there is a concern of pressure loss in a place where the passage cross-sectional area becomes narrow. Further, when the current flowing through the battery unit 10 is small, the amount of heat generated by each battery cell 31 is small, and a temperature difference between the battery cells 31 due to air cooling is unlikely to occur. In such a case, it is not necessary to change the degree of heat dissipation from each battery cell 31 to the cooler 40 depending on the location.

Therefore, the cooler 40 is provided with a cross-sectional area variable member 156 that makes the passage cross-sectional area of the refrigerant passage 141 variable. The cross-sectional area variable member 156 is made of, for example, a temperature-sensitive material that changes to a memorized shape depending on the temperature, such as a shape memory alloy. The cross-sectional area variable member 156 has a narrow passage cross-sectional area in the passage region (intermediate portion 155) corresponding to the battery cell 31C in the intermediate portion where the temperature becomes high, and a passage in the passage region corresponding to the outer battery cells 31A and 31B which becomes low in temperature. It is deformed so that the cross-sectional area becomes wider. Specifically, the cross-sectional area variable member 156 is provided on the second wall portion 52, and projects into a stored shape according to the temperature of each battery cell 31 in contact with the cooler 40 to partially reduce the passage cross-sectional area. Narrow to.

As a result, in a state where a temperature difference occurs between the battery cells 31, the passage cross-sectional area of the passage region (intermediate portion 155) corresponding to the battery cell 31C in the intermediate portion where the degree of air cooling is small and the temperature becomes high becomes large. It becomes relatively narrow. On the other hand, when there is no temperature difference, that is, when some of the battery cells 31 do not become hot, all the battery cells 31 become cold in the front-rear direction, and the passage cross-sectional area does not change in the front-rear direction. Therefore, it is possible to partially change the speed only when necessary and suppress the occurrence of pressure loss when it is not necessary.

-The shape for narrowing the cross-sectional area of the passage may be another shape. For example, as shown in FIG. 7, the protrusion 256A that narrows the passage cross-sectional area may be linear. The linear shape facilitates molding. Further, as shown in FIG. 8, the passage cross-sectional area may be different for each position corresponding to each battery cell 31. Specifically, the dimensions between the first wall portion 51 and the protruding portion 256B may be different for each region corresponding to each battery cell 31 in the refrigerant passage 241. This makes it easier to adjust the amount of heat released from each battery cell 31. Further, as shown in FIG. 9, in order to reduce the pressure loss, the corner portion of the protruding portion 256C may have an R shape.

As shown in FIG. 10, the refrigerant passage 341 of the cooler 340 has a partially narrow passage cross-sectional area in a direction orthogonal to the refrigerant flow direction (front-rear direction) in the facing surface facing the plurality of battery cells 31. It may be. Specifically, the refrigerant passage 341 is narrowed in the width direction at the intermediate portion 355. As a result, the passage cross-sectional area can be changed even when the passage cross-sectional area cannot be narrowed in the vertical direction. It is desirable that the width of the cooler 340 is larger than the width of the battery block 30 so that all the battery cells 31 are in contact with the cooler 340 even at the narrowest position in the width direction. Further, an obstacle having an airfoil cross section may be provided in the refrigerant passage 341 to narrow the passage cross-sectional area in the width direction. The passage cross-sectional area can be narrowed in the direction across the plurality of battery cells 31 (front-back direction), and the passage cross-sectional area can be made different in the orthogonal direction (width direction).

As shown in FIG. 11, when there is a heat source H such as a junction board or a DC / DC converter near the battery module 20, and some battery cells 31 receive heat from the heat source H, the cooler 440 The cross-sectional area of the refrigerant passage 441 in the vicinity of the heat source H may be narrowed.

-In the above embodiment, a plurality of battery modules 20 are connected in series to form the battery unit 10, but one battery module 20 may form the battery unit 10. Further, the battery units 10 may be configured by connecting the battery modules 20 in parallel.

-In the above embodiment, the refrigerant passages 41 of the plurality of battery modules 20 are connected in series, and the refrigerant that has passed through the upstream battery module 20 flows into the downstream battery module 20, but each battery module The refrigerant may be supplied to and discharged from 20. For example, a supply pipe for supplying a refrigerant is provided to each of the plurality of battery modules 20 arranged in a row, and the refrigerant is supplied from the supply pipe to each refrigerant passage 41. Then, a discharge pipe for flowing the refrigerant discharged from each refrigerant passage 41 may be provided, and the refrigerant may flow from the discharge pipe to the circulation pump 61.

10 ... Battery unit, 30 ... Battery block, 31 ... Battery cell, 40 ... Cooler, 41 ... Refrigerant passage.

Claims (7)

A battery block (30) provided by arranging a plurality of battery cells (31),
A cooler (40, 140, 240, 340) provided with each of the plurality of battery cells facing each other and having a refrigerant passage (41,141,241,341) for flowing a refrigerant in a direction crossing the plurality of battery cells. And with
The refrigerant passages are provided so that the cross-sectional areas of the passages differ in the refrigerant flow direction, and in the passage region crossing the battery cell (31C) having a small degree of air cooling, the battery cells (31A, 31B) having a large degree of air cooling ) Is smaller than the passage area across the passage area (10). The battery unit according to claim 1, wherein in the refrigerant passage, the passage cross-sectional area is reduced at an intermediate portion (55,155,355) between the passage inlet (53) and the passage outlet (54). The cooler has a first wall portion (51) on the battery block side and a second wall portion (52) facing the first wall portion, and the refrigerant passage is formed between them. Ori,
The first or second aspect of the present invention, wherein the second wall portion is provided with a projecting portion (56,256) projecting toward the first wall portion, and the passage cross-sectional area is narrowed by the projecting portion. Battery unit. The invention according to any one of claims 1 to 3, wherein the refrigerant passage has a narrow passage cross-sectional area in a direction orthogonal to the refrigerant flow direction in the facing surface facing the plurality of battery cells. Battery unit. The cooler has a cross-sectional area variable member (156) that makes the passage cross-sectional area of the refrigerant passage variable.
The cross-sectional area variable member can be deformed according to the temperature, the passage cross-sectional area of the passage region corresponding to the high temperature battery cell is narrow, and the passage cross-sectional area of the passage region corresponding to the low temperature battery cell is wide. The battery unit according to any one of claims 1 to 4, which is deformed as described above. A plurality of battery modules (20) having the battery block and the cooler are provided.
The plurality of battery modules are configured such that the refrigerant passages of the respective coolers are connected in series.
One of claims 1 to 5, wherein the average passage cross-sectional area of the battery module on the upstream side of the plurality of battery modules is larger than the average passage cross-sectional area of the battery module on the downstream side of the plurality of battery modules. The battery unit described in item 1. A plurality of battery modules (20) having the battery block and the cooler are provided.
The plurality of battery modules are configured such that the refrigerant passages of the respective coolers are connected in series.
The dimension in the refrigerant flow direction of the region where the passage cross-sectional area of the battery module on the upstream side of the plurality of battery modules is small is such that the passage cross-sectional area of the battery module on the downstream side of the plurality of battery modules is small. The battery unit according to any one of claims 1 to 5, which is smaller than the dimension in the refrigerant flow direction in the region.

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