Battery module

Abstract

To provide a battery module that can equalize the surface pressure of battery cells. [Solution] The battery module 1 comprises a battery cell stack 100 in which a plurality of battery cells 10 are stacked, a pair of end plates 110 provided at both ends of the stacking direction 1001 of the battery cell stack 100, and a fluid cushion 20 disposed between the stacked battery cells 10. The module further comprises a fluid tank 2010 connected to the fluid cushion 20, a compressor 2012 connected to the fluid tank 2010, and a control unit 2050. The control unit 2050 controls the operation of the compressor 2010 so that the pressure inside the fluid cushion 20 becomes uniform in response to at least one of the expansion and contraction of the fluid cushion 20.

Description

Technical Field

[0001] The present invention relates to a battery module.

Background Art

[0002] In recent years, efforts toward realizing a low-carbon society or a decarbonized society have intensified, and research and development related to battery modules have been conducted in vehicles as well to reduce CO2 emissions and improve energy efficiency. Regarding battery modules, for example, Patent Document 1 discloses a technique of providing a fluid supply device between a plurality of stacked battery cells.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0004] Meanwhile, in a battery module, in order to stabilize battery performance and improve the durability of the battery cells included in the battery module, it is preferable to equalize the surface pressure of the battery cells and further keep the temperature of the battery cells constant. However, up to now, particularly in battery modules in which a plurality of battery cells are stacked, a technique for ensuring the pressure equalization property and temperature equalization property of each battery cell has not been sufficiently established.

[0005] The present application aims to provide a battery module capable of equalizing the surface pressure of battery cells in order to solve the above problems. Furthermore, the present application aims to provide a battery module capable of equalizing the temperature of battery cells. This in turn contributes to the improvement of energy efficiency.

Means for Solving the Problems

[0006] (1) The battery module comprises a battery cell stack in which a plurality of battery cells are stacked, a pair of end plates provided at both ends of the stacking direction of the battery cell stack, and a fluid cushion disposed between the stacked battery cells, and further comprises a fluid tank connected to the fluid cushion, a compressor connected to the fluid tank, and a control unit, wherein the control unit controls the operation of the compressor so that the pressure in the fluid cushion becomes uniform in response to at least one of the expansion and contraction of the fluid cushion.

[0007] Such a battery module makes it possible to maintain uniform surface pressure across the battery cells. In particular, it makes it easier to maintain pressure equality across each battery cell in a battery module where multiple battery cells are stacked.

[0008] (2) The battery module further comprises a liquid, a liquid tank connected to the fluid cushion as a fluid tank, a water pump connected to the fluid tank as a compressor, and a control unit, wherein the control unit controls the operation of the compressor in accordance with at least one of the expansion and contraction of the fluid cushion so that the pressure inside the fluid cushion becomes uniform.

[0009] Such a battery module makes it possible to coordinate the expansion and contraction of the fluid, even when it is a liquid, without placing an inappropriate load on the battery cells and fluid cushion.

[0010] (3) The battery module further comprises an air tank as a fluid tank connected to the fluid cushion, a compressor connected to the air tank, and a control unit, wherein the control unit controls the operation of the compressor in accordance with at least one of the expansion and contraction of the fluid cushion so that the pressure inside the fluid cushion becomes uniform.

[0011] Such a battery module makes it possible to coordinate expansion and contraction of the fluid, even when it is a gas, without placing an inappropriate load on the battery cells and fluid cushion.

[0012] (4) In the battery module, the fluid contained in the fluid cushion is a liquid, and the battery cells may be cooled by the fluid cushion.

[0013] With such a battery module, the fluid cushion can cool the battery cells in addition to providing coordinated control over expansion and contraction.

[0014] (5) In the battery module, the fluid contained in the fluid cushion is a liquid, and the module further comprises a cushion connecting portion that connects the fluid cushion, and the fluid cushion and the cushion connecting portion together are defined as a pressurized structure, and the pressurized structure may branch off the vehicle cooling passage of the vehicle on which the battery cell is mounted.

[0015] With this type of battery module, the battery cells can be cooled by the liquid flowing through the vehicle's cooling channels via a fluid cushion. This enables efficient cooling of the battery cells.

[0016] (6) The battery module may have a pressurized structure that branches off the vehicle cooling channel through a water jacket that cools the battery cell stack.

[0017] With this type of battery module, the battery cells can be cooled by a fluid flowing through a water jacket via a fluid cushion. This enables efficient cooling of the battery cells.

[0018] (7) The battery module further comprises a tank sensor unit that detects at least one of the expansion and contraction of the fluid tank, and the control unit may determine the charge state of the battery cell based on the result detected by the tank sensor unit.

[0019] Such battery modules allow for a more accurate determination of the charge state of the battery cells.

[0020] (8) In the battery module, the fluid cushion includes cell fixing parts for positioning adjacent battery cells in the stacking direction.

[0021] Such a battery module allows for the fixing of battery cells in desired positions while suppressing the increase in the size of the battery module. Specifically, by providing a section on the fluid cushion side for positioning the stacked battery cells and the fluid cushion, the positioning can be maintained while coordinating control of at least one of the expansion and contraction of individual battery cells and the expansion and contraction of the fluid cushion. Furthermore, even when the battery module is miniaturized, while ensuring a flow path with other fluid cushions, the energy density can be increased, ultimately enabling the realization of a small, high-capacity battery module.

[0022] (9) In the battery module, the fluid cushion includes a flange portion, and the flange portion may include a recess having a shape that conforms to the shape of the end of the battery cell as the cell fixing portion.

[0023] According to such a battery module, the recess enables reliable positioning of the battery cells with a simple configuration. ADVANTAGEOUS EFFECTS OF INVENTION

[0024] According to the present invention, it is possible to provide a battery module capable of fixing battery cells at desired positions while suppressing an increase in the size of the battery module. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] [Figure 1] Figure 1 is a cross-sectional view of a battery module according to an embodiment of the present invention. [Figure 2] Figure 2 is an enlarged view showing the framed region 1101 in Figure 1. [Figure 3] Figure 3 is a perspective view of a fluid cushion. [Figure 4] Figure 4 is a cross-sectional view taken along line 1200-1200 in Figure 3. [Figure 5] Figure 5 is a diagram showing a state in which fluid cushions and battery cells are stacked. [Figure 6] Figure 6 is a perspective view of the stacked fluid cushions. [Figure 7] Figure 7 is a cross-sectional view corresponding to the cross-section taken along line 1210-1210 in Figure 5. [Figure 8] Figure 8 is a cross-sectional view corresponding to Figure 7 in the prior art. [Figure 9] Figure 9 is a diagram of the fluid cushions and battery cells shown in Figure 6, viewed along the stacking direction. [Figure 10] Figure 10 is a cross-sectional view schematically showing the connection between a fluid flow passage portion and a flange portion. [Figure 11] Figure 11 is a perspective view of a fluid cushion according to an embodiment of the present invention. [Figure 12] Figure 12 is a perspective view of a flange portion. [Figure 13]Figure 13 is a cross-sectional view that models the cross-sectional view shown in Figure 10, with an increased number of battery cells and fluid cushion layers, illustrating the connection between the fluid flow channel and the flange. [Figure 14] Figure 14 is a cross-sectional view showing an overview of the connection between the fluid flow channel and the flange, illustrating a modified example of the example shown in Figure 13 with a different material. [Figure 15] Figure 15 is a cross-sectional view showing an overview of the connection between the fluid flow channel and the flange, illustrating a modified example in which a holder has been added to the example shown in Figure 13. [Figure 16] Figure 16 shows a modified example in which a welded holding section has been added to the example shown in Figure 13, and is a cross-sectional view corresponding to the section taken along line 1222-1222 in Figure 17. [Figure 17] Figure 17 shows a view of the fluid cushion with the welded holding section added, along the stacking direction. [Figure 18] Figure 18 shows an example of the stacking of flange sections. [Figure 19] Figure 19 is an exploded perspective view of the power unit. [Figure 20] Figure 20 shows the fluid flow between the power unit and the vehicle body. [Figure 21] Figure 21 shows a power unit and other components that are further equipped with pressure sensors. [Figure 22] Figure 22 shows a vehicle body and other components further equipped with a tank sensor unit. [Figure 23] Figure 23 shows a power unit with an additional water jacket. [Figure 24] Figure 24 shows a power unit with the water jacket omitted. [Figure 25] Figure 25 shows an overview of an example of a vehicle cooling system. [Modes for carrying out the invention]

[0026] (Battery module) Embodiments for carrying out the present invention will be described with reference to the drawings. The embodiments shown below are illustrative of the present invention. The present invention is not limited to what is described below.

[0027] Figure 1 is a cross-sectional view of a battery module 1 according to an embodiment of the present invention. Figure 2 is an enlarged view of the framed area 1101 in Figure 1. As shown in Figures 1 and 2, the battery module 1 comprises a battery cell stack 100 and an end plate 110.

[0028] The battery cell stack 100 comprises battery cells 10 and a fluid cushion 20. Multiple battery cells 10 are stacked in the battery cell stack 100. The direction in which the battery cells 10 are stacked is called the stacking direction 1001. The fluid cushion 20 is positioned between the stacked battery cells 10.

[0029] The end plates 110 are positioned at both ends of the battery cell stack 100 in the stacking direction 1001. Figure 1 shows only the end plate 110 positioned at one end of the battery cell stack 100.

[0030] Figure 1 shows the flow path direction 1002. The flow path direction 1002 is the direction along which the fluid flows in the fluid cushion 20. The flow path direction 1002 is perpendicular to the stacking direction 1001.

[0031] As shown in Figures 1 and 2, the fluid cushion 20 comprises a fluid channel section 22 and flange sections 50. The fluid channel section 22 is a form of cooling channel. The flange sections 50 are provided at both ends of the fluid channel section 22 in the flow direction 1002.

[0032] The flange portion 50 is stacked in the stacking direction 1001 at both ends of the flow path direction 1002 of the battery cell stack 100.

[0033] The battery cell 10 includes a cell terminal portion 12 and a tab lead 14. The cell terminal portion 12 and the tab lead 14 are provided at both ends in the flow direction 1002. The cell terminal portion 12 is drawn out on both sides in the flow direction 1002 of the battery cell stack 100 through the stacked flange portions 50. The tab lead 14 is formed continuously with the cell terminal portion 12. The battery cell 10 is connected to the bus bar 3 via the tab lead 14.

[0034] (Fluid cushion) The fluid cushion 20 will be described with reference to Figure 3. Figure 3 is a perspective view of the fluid cushion 20. Figure 3 shows one of several fluid cushions 20 included in the battery cell stack 100. The direction perpendicular to the stacking direction 1001 and the flow path direction 1002 is called the width direction 1003.

[0035] The shape of the fluid channel section 22 is rectangular when viewed along the stacking direction 1001. In the cross-section of the fluid channel section 22 in the width direction 1003, a space is formed that serves as a fluid channel. Flange sections 50 are provided at both ends of the fluid channel section 22 in the flow direction 1002. The flange sections 50 are formed to cover the entire width direction 1003 at the ends of the fluid channel section 22 in the flow direction 1002.

[0036] The fluid channel section 22 can be a laminate of, for example, resin and metal. An example of such a laminate is a polypropylene-aluminum-polypropylene laminate.

[0037] The flange portion 50 can be made of, for example, a molded resin. An example of a resin that makes up the flange portion 50 is polypropylene.

[0038] The portion where the fluid channel section 22 and the flange section 50 are fixed is called the cell fixing portion. In this embodiment, the fluid channel section 22 and the flange section 50 are fixed by welding. The portion where the fluid channel section 22 and the flange section 50 are welded together is called the welded portion 80. The welded portion 80 is a form of the cell fixing portion.

[0039] When welding the fluid channel section 22 and the flange section 50, the welding can be, for example, heat welding. However, the type of welding is not limited to heat welding. The welding may also be high-frequency welding, ultrasonic welding, or laser welding. The fixing of the fluid channel section 22 and the flange section 50 will be described later.

[0040] The fluid channel section 22 is formed of a laminate body 24. Figure 4 is a cross-sectional view taken along the line 1200-1200 in Figure 3.

[0041] The portion that defines the outer shape of the fluid channel section 22 is called the laminate body 24. The laminate body 24 has a closed shape in the 1200-1200 line cross-section. The cavity surrounded by the laminate body 24 becomes the flow path. The fluid flows through the flow path.

[0042] In the fluid flow channel section 22, fluid flows along the flow channel direction 1002, from one end of the flow channel direction 1002 to the other end.

[0043] (Function of fluid cushion) The volume of the battery cell 10 changes depending on the charging and discharging of the battery cell 10. The fluid channel section 22 has the function of absorbing the volume of the battery cell 10. For example, when the battery cell 10 is charged and expands, the amount of fluid flowing through the channel decreases. When the amount of fluid decreases, the cross-sectional area of ​​the channel decreases. In this way, the fluid channel section 22 absorbs the increase in the volume of the battery cell 10.

[0044] On the other hand, when the battery cell 10 discharges and shrinks, the amount of fluid flowing through the channel increases. When the amount of fluid increases, the cross-sectional area of ​​the cavity surrounded by the laminate 24 increases. As a result, the fluid channel section 22 absorbs the decrease in volume of the battery cell 10. In this way, the fluid channel section 22 absorbs the volume pulsation of the battery cell 10, making it easier to maintain a constant volume of the battery cell stack 100.

[0045] The fluid flow channels 22 are provided between each of the battery cells 10. Therefore, the fluid flow channels 22 can coordinately respond to the expansion and contraction of each battery cell 10.

[0046] Furthermore, the fluid cushion 20 can cool the battery cells 10. The temperature of the battery cells 10 rises during charging. By circulating fluid within the fluid cushion 20, heat exchange can occur between the battery cells 10 and the fluid. As a result of this heat exchange, the temperature of the battery cells 10 can be reduced.

[0047] (Flange structure) Referring to Figure 3, the configuration of the flange portion 50 will be described. As shown in Figure 3, the flange portion 50 comprises a flange extension portion 53, a first laminated portion 51, and a second laminated portion 52. The first laminated portion 51 is provided at one end of the flange extension portion 53 in the width direction 1003. The second laminated portion 52 is provided at the other end of the flange extension portion 53 in the width direction 1003.

[0048] The flange extension portion 53 is the part that covers most of the end of the fluid flow channel portion 22 in the flow direction 1002. The flange extension portion 53 has an elongated shape in the width direction 1003.

[0049] The first laminated portion 51 and the second laminated portion 52 are the parts where adjacent fluid cushions 20 in the laminated direction 1001 come into contact when multiple fluid cushions 20 are laminated. The laminated portions will be described with reference to Figures 5 and 6.

[0050] Figure 5 shows how the fluid cushion 20 and the battery cell 10 are stacked. Figure 6 is a perspective view of the stacked fluid cushion 20. Figures 5 and 6 show portions of the fluid cushion 20 and the battery cell 10.

[0051] Figure 5 shows the stacking direction 1220. The stacking direction 1220 is the direction in which the fluid cushion 20 and battery cells 10 are stacked in sequence. The stacking direction 1220 is parallel to the stacking direction 1001.

[0052] Figure 5 shows the upward direction 1011 and the downward direction 1012. The upward direction 1011 and the downward direction 1012 are parallel to the stacking direction 1001. The upward direction 1011 and the downward direction 1012 represent opposite directions. In the following description, "up and down" refers to the upward direction 1011 and the downward direction 1012.

[0053] The two fluid cushions 20 are stacked in the direction indicated by the stacking direction 1220, with the battery cell 10 sandwiched between them. The two fluid cushions 20 are stacked such that their first stacking portions 51 are stacked together in the stacking direction 1001, and their second stacking portions 52 are stacked together in the stacking direction 1001.

[0054] In the example shown in Figure 5, the upper surface 61 of the first laminated portion 51 is provided with a fitting projection 55. The lower surface 62 of the first laminated portion 51 is provided with a fitting recess (not shown). When the two first laminated portions 51 are stacked, the fitting projection 55 on the upper surface 61 of the lower first laminated portion 51 is fitted into the fitting recess on the lower surface 62 of the upper first laminated portion 51.

[0055] Furthermore, a fitting recess 56 is provided on the upper surface 61 of the second laminated portion 52. A fitting projection (not shown) is provided on the lower surface 62 of the second laminated portion 52. When the two second laminated portions 52 are stacked, the fitting projection on the lower surface 62 of the upper second laminated portion 52 is fitted into the fitting recess 56 on the upper surface 61 of the lower second laminated portion 52.

[0056] By stacking the fluid cushion 20 such that the first stacked sections 51 fit together and the second stacked sections 52 fit together, the fluid cushion 20 can be stacked in an accurate position without any misalignment.

[0057] Figure 6 shows how the first stacked sections 51 are fitted together and stacked. Note that in the example shown in Figure 6, the top-bottom relationship between the fitting recess and fitting protrusion is reversed compared to the example shown in Figure 5. In the example shown in Figure 6, contrary to the example shown in Figure 5, a fitting recess 56 is provided on the upper surface 61 of the first stacked section 51, and a fitting protrusion (not shown) is provided on the lower surface 62 of the first stacked section 51. As shown in Figure 6, by stacking the first stacked sections 51 so that the fitting protrusion fits into the fitting recess 56, the fluid cushion 20 can be stacked in the correct position.

[0058] O-rings (not shown) may be placed between the stacked first stacked portions 51 and between the stacked second stacked portions 52.

[0059] (Misalignment of fluid flow channels and battery cells) The positional misalignment of the fluid channel section 22 and the battery cell 10 will be explained. Figure 7 is a cross-sectional view of the fluid channel section 22, etc., corresponding to the 1210-1210 line section in Figure 5. Figure 8 is a cross-sectional view of the conventional fluid channel section 22, etc., corresponding to Figure 7. Figures 7 and 8 show cross-sections of the fluid channel section and battery cell stacked together.

[0060] Figures 5 and 7 show the first positioning line 1231 and the second positioning line 1232. The first positioning line 1231 is a line indicating the position of the end of the first laminated section 51 in the width direction 1003. The second positioning line 1232 is a line indicating the position of the end of the second laminated section 52 in the width direction 1003.

[0061] Figure 7 shows the first fluid flow channel end line 1241 and the second fluid flow channel end line 1242. The first fluid flow channel end line 1241 and the second fluid flow channel end line 1242 are lines that indicate the positions of the ends of the fluid flow channel 22 in the width direction 1003.

[0062] As explained with reference to Figure 6, the first stacked portions 51 and the second stacked portions 52 are stacked in precise positions without any misalignment. Therefore, as shown in Figure 7, the ends of the two stacked flange portions 50 are aligned with the first positioning line 1231 and the second positioning line 1232.

[0063] In the fluid cushion 20 of this embodiment, the fluid channel section 22 is fixed to the flange section 50 in advance. Therefore, when the flange section 50 is aligned, the fluid channel section 22 is also aligned. As shown in Figure 7, the ends of the two stacked fluid channel sections 22 are aligned with the end line 1241 of the first fluid channel section and the end line 1242 of the second fluid channel section.

[0064] This allows for precise and accurate pressurization of the desired area within the battery cell 10 without any misalignment. As a result, the desired battery performance can be achieved.

[0065] In contrast, conventional technology does not include a flange portion in the fluid cushion. Therefore, as shown in Figure 8, the ends of the stacked fluid flow channels 22 are not aligned. As a result, the pressurized position of the battery cell 10 is shifted from the desired position. Consequently, the desired battery performance cannot be achieved.

[0066] (Positioning of battery cells) The positioning of the battery cells 10 will be explained with reference to Figures 6 and 9. Figure 9 is a view of the fluid cushion 20 and battery cells 10 shown in Figure 6 along the stacking direction 1001. The fluid cushion 20 in this embodiment is provided with cell fixing parts 70 for positioning adjacent battery cells 10 in the stacking direction 1001. Specifically, the cell fixing parts 70 are provided on the flange portion 50 of the fluid cushion 20. More specifically, the cell fixing parts 70 are provided on the stacking portion of the flange portion 50. The cell fixing parts 70 will be explained below using the first stacking portion 51 as an example. The matters described below also apply to the second stacking portion 52.

[0067] (Cell fixing part) As shown in Figures 6 and 9, the shape of the first laminated portion 51 is approximately rectangular when viewed along the lamination direction 1001. When viewed along the lamination direction 1001, the first laminated portion 51 has a shape in which one corner of the rectangular shape is cut off. In other words, the first laminated portion 51 has a stepped shape due to the cut-off corner.

[0068] In the first laminated section 51, the portion where the corner is cut off is called a recess. In the examples shown in Figures 6 and 9, the cell fixing section 70 is a recess.

[0069] (End of battery cell) The shape of the end of the battery cell 10 will be described with reference to Figures 6 and 9. The end of the battery cell 10 is called the cell end 16. The portion of the flange portion 50 at the cell end 16 that corresponds to the cell fixing portion 70 has a shape that follows the cell fixing portion 70. In other words, the shape of the cell fixing portion 70 of the flange portion 50 follows the shape of the cell end 16.

[0070] A positioning portion 18 is provided in the portion of the flange portion 50 at the cell end 16 that corresponds to the cell fixing portion 70. In the examples shown in Figures 6 and 9, the positioning portion 18 is the portion of the battery cell 10 that has been cut out at the corner. When viewed along the stacking direction 1001, the positioning portion 18 has a shape that aligns with the cell fixing portion 70.

[0071] Furthermore, the statement that the cell fixing portion 70 and the positioning portion 18 have shapes aligned with each other does not merely mean that the shapes of the cell fixing portion 70 and the positioning portion 18 coincide when viewed along the stacking direction 1001.

[0072] Figures 6 and 9 show the positioning shape line 1250. The positioning shape line 1250 is a line that shows the approximate shape of the positioning part 18. The statement that the cell fixing part 70 and the positioning part 18 have shapes aligned with each other means that the shape of the cell fixing part 70 is approximately the same as the positioning shape line 1250.

[0073] In the battery module 1 of this embodiment, the fluid cushion 20 is equipped with a cell fixing portion 70, which allows for accurate positioning of the battery cells 10. When stacking the fluid cushion 20 and the battery cells 10, they are stacked so that the cell fixing portion 70 and the positioning portion 18 engage with each other. By stacking them in this manner, the battery cells 10 can be accurately positioned in the flow path direction 1002 and the width direction 1003.

[0074] In the battery module 1 of this embodiment, even when stacking a large number of battery cells 10, such as about 30, the battery cells 10 can be accurately positioned.

[0075] Furthermore, the dimensions of the battery cell 10 change as the battery cell 10 is charged and discharged. In other words, the dimensions of the battery cell 10 pulsate. In the battery module 1 of this embodiment, even when the dimensions of the battery cell 10 pulsate, displacement of the battery cell 10 is suppressed, and the battery cell 10 can be positioned in the correct location.

[0076] Note that the concave shape of the cell fixing portion 70 shown in Figures 6 and 9 is illustrative. The shape of the cell fixing portion 70 is not limited to a shape with cut-out corners. The concave shape may be other shapes. Also, the shape of the cell fixing portion 70 is not limited to a concave shape. The shape of the cell fixing portion 70 may be convex, or a concave-convex shape combining concave and convex parts.

[0077] Furthermore, the cell fixing portion 70 is not limited to a configuration in which a recess or protrusion is formed on the flange portion 50 when viewed along the stacking direction 1001, such as by cutting out a part of the flange portion 50. The cell fixing portion 70 may be, for example, a notch formed in the flange portion 50, particularly in the stacking portion, extending in at least one of the flow direction 1002 and the width direction 1003. If the cell fixing portion 70 is a notch, the battery cell 10 can be accurately positioned by inserting the cell end 16 into the notch.

[0078] Furthermore, the cell fixing portion 70 may be provided such that a gap is formed between the cell end portion 16 and the flange portion 50 in at least one of the flow direction 1002 and the width direction 1003. By forming a gap, the stacked state of the battery cell 10 and the fluid cushion 20 can be properly maintained even if the dimensions of the battery cell 10 change due to charging and discharging.

[0079] (Connection between the fluid flow channel and the flange) The connection between the fluid channel section 22 and the flange section 50 will now be described. Figure 10 is a cross-sectional view showing an overview of the connection between the fluid channel section 22 and the flange section 50. Figure 11 is a perspective view of the fluid cushion 20 according to one embodiment of the present invention. Figure 12 is a perspective view of the flange section 50. Figure 12 shows the flange section 50 before the fluid channel section 22 is connected. By connecting the fluid channel section 22 to the flange section 50 shown in Figure 12, the fluid cushion 20 shown in Figure 11 is formed.

[0080] Figure 10 corresponds to the cross-sectional view along line 1201-1201 in Figure 11. Note that, unlike Figure 11, Figure 10 depicts battery cells 10 on both sides of the fluid flow channel 22 in the stacking direction 1001.

[0081] Note that the fluid cushion 20 shown in Figure 11 has a slightly different configuration from the fluid cushion 20 shown in Figure 3 and other figures. The following explanation will focus on the connection between the fluid flow channel 22 and the flange 50. The fluid cushion 20 of the present invention also includes a fluid cushion 20 that combines the configuration of the fluid cushion 20 shown in Figure 11 and the configuration of the fluid cushion 20 shown in Figure 3.

[0082] Referring to Figure 10, the forces acting on the fluid channel section 22 and the flange section 50 will be explained. The dimensions of the battery cell 10 change with charging and discharging. Also, the temperature of the battery cell 10 changes with charging and discharging. The fluid channel section 22 is sandwiched between the battery cell 10. Therefore, various forces act on the fluid channel section 22. The flange section 50 is connected to the fluid channel section 22. Therefore, various forces also act on the flange section 50.

[0083] The configuration of the flange portion 50 shown in Figure 10 will now be described. The flange portion 50 comprises a flange body 65 and a flange connection portion 66. The flange connection portion 66 is a portion that protrudes from the flange body 65 toward the fluid flow path portion 22 in order to facilitate connection between the flange portion 50 and the fluid flow path portion 22. The fluid flow path portion 22 is connected to the flange portion 50 at the flange connection portion 66. The flange connection portion 66 has a cylindrical shape. A flange flow path portion 67 for the flow of fluid is formed inside the flange portion 50. The flange flow path portion 67 is formed through the flange connection portion 66 and the flange body 65.

[0084] Figure 10 shows the connection region 1301, the boundary region 1302, and the flow path region 1303. The connection region 1301 is the region where the fluid flow path section 22 and the flange section 50 are connected. The connection region 1301 corresponds to the welded section 80. The boundary region 1302 is the boundary region between the flange body 65 and the flange connection section 66. The flow path region 1303 is the region of the inner wall of the flange flow path section 67.

[0085] The load acting on the fluid cushion 20 will now be explained. A load is mainly generated by applying internal pressure to the fluid, or more specifically, by applying pressure to the cells due to the internal pressure. In addition, there is also a load due to the effect of thermal expansion, which will be explained below. When pressure is applied to the fluid in the fluid channel section 22, a force acts on the fluid channel section 22 in a direction that expands the channel. This force is called the peeling force 1311. When the peeling force 1311 acts on the connection region 1301, it causes separation between the laminate body 24 and the flange connection section 66.

[0086] The forces acting on the boundary region 1302 will now be explained. For example, if the materials of the flange body 65 and the flange connection portion 66 are different, a force will be generated in the boundary region 1302 that will cause the flange body 65 and the flange connection portion 66 to separate. If the thermal expansion coefficients of the material of the flange body 65 and the material of the flange connection portion 66 are different, a change in the temperature of the boundary region 1302 will cause a force due to the difference in thermal expansion coefficients to act on the boundary region 1302. This force will cause the flange body 65 and the flange connection portion 66 to separate.

[0087] Furthermore, a shear force, or force acting in the shear direction, is also generated in the boundary region 1302. This shear force also causes separation between the flange body 65 and the flange connection portion 66.

[0088] The forces acting on the flow path region 1303 are described below. A force acts on the flow path region 1303 that attempts to deform the flange flow path portion 67 in a direction that expands it. This force is called the deformation force 1312. The deformation force 1312 is caused by the pressure and movement of the fluid as it passes through the flange flow path portion 67. The deformation force 1312 is the cause of deformation of the flange flow path portion 67.

[0089] As described above, the portion where the fluid channel section 22 and the flange section 50 are connected is subjected to peeling forces and shear forces in response to changes in temperature and pressure. These forces can affect the reliability and durability of the portion where the fluid channel section 22 and the flange section 50 are connected. Therefore, it is important to consider these forces during the design phase.

[0090] Regarding the reliability of the connection between the fluid flow channel section 22 and the flange section 50, the separation force generated by the internal pressure of the fluid flow channel between the fluid flow channel section 22 and the flange section 50 is a particular problem.

[0091] The temperature of the battery cell 10 changes as it charges and discharges. This temperature change also causes temperature changes in the fluid flow channel 22 and the flange 50. Typically, the thermal expansion coefficients of the fluid flow channel 22 and the flange 50 are different.

[0092] As explained earlier, the fluid channel section 22 is a laminate formed by laminating, for example, a resin layer and a metal layer. Furthermore, the fluid channel section 22 is formed to be expandable and contractible.

[0093] On the other hand, the flange portion 50 is rigidly formed, for example, from resin. Unlike the fluid flow channel portion 22, the flange portion 50 is formed to minimize dimensional changes.

[0094] Due to the difference in physical properties between the fluid flow channel section 22 and the flange section 50, it is important to ensure connection reliability between the fluid flow channel section 22 and the flange section 50.

[0095] Incidentally, one requirement for the battery module 1 is that it be small. For example, each part included in the battery module 1 may have a scale of several millimeters. Therefore, even if one tries to make the connection between the fluid flow channel section 22 and the flange connection section 66 in the connection area 1301 firm, it is difficult to fix them using screws or the like. Thus, it is necessary to make the connection between the fluid flow channel section 22 and the flange connection section 66 compact and firm without being bulky. Below, the configuration of the part connecting the fluid flow channel section 22 and the flange connection section 66 will be described from the viewpoint of suppressing separation between the fluid flow channel section 22 and the flange connection section 66.

[0096] (welded part) Figure 13 is a cross-sectional view showing an overview of the connection between the fluid channel section 22 and the flange section 50, modeled after the cross-sectional view shown in Figure 10, with an increased number of layers for the battery cell 10 and fluid cushion 20. As mentioned above, the main cause of separation between the fluid channel section 22 and the flange section 50 is the internal pressure of the channel 26. Figure 13 shows the peeling load 1332. The peeling load 1332 is a load acting on the portion where the laminate body 24 and the flange connection section 66 are connected. The peeling load 1332 acts in a direction that separates the laminate body 24 and the flange connection section 66. The peeling load 1332 is mainly caused by the pressure inside the fluid channel section 22.

[0097] The connection between the laminate body 24 and the flange connection portion 66 preferably has sufficient strength to absorb the peel load 1332. In the battery module 1 of this embodiment, the laminate body 24 and the flange connection portion 66 are connected and fixed by welding. The portion where the laminate body 24 and the flange connection portion 66 are connected and fixed by welding is called the welded portion 80. In other words, the battery module 1 of this embodiment is provided with a welded portion 80. Furthermore, the welded portion 80 has sufficient strength to absorb the peel load 1332.

[0098] The welded portion 80 is formed by welding the portion of the laminate body 24 that contacts the flange connection portion 66 to the portion of the flange connection portion 66 that contacts the laminate body 24. Therefore, at least a part of the welded portion 80 is part of the laminate body 24, and at least a part of the welded portion 80 is part of the flange connection portion 66. In other words, the welded portion 80 includes the welded portion 80 as part of the laminate body 24 and the welded portion 80 as part of the flange connection portion 66.

[0099] In this embodiment, the battery module 1 is provided with a welded portion 80, which ensures the connection strength between the fluid flow path portion 22 and the flange portion 50. Furthermore, the welded portion 80 is less bulky compared to other fastening means, such as screws. Therefore, providing the welded portion 80 makes it easier to adapt to requirements for miniaturization and thinning of the battery module 1. As a result, even when the battery module 1 is miniaturized, the energy density can be increased. Ultimately, a small, high-capacity battery module 1 can be realized.

[0100] To increase the strength of the welded joint 80, it is possible to use the same material for the laminate body 24 and the flange connection part 66. Even if the materials of the laminate body 24 and the flange connection part 66 are not the same, the laminate body 24 and the flange connection part 66 can still be welded together. However, if the materials of the laminate body 24 and the flange connection part 66 are the same, the strength of the welded joint 80 can be increased even further. As explained earlier, the laminate body 24 can be, for example, a polypropylene-aluminum-polypropylene laminate. Therefore, by using polypropylene for the material of the flange connection part 66, the strength of the welded joint 80 can be increased even further.

[0101] However, polypropylene generally has low material strength. Therefore, if the flange connection portion 66, and by extension the entire flange portion 50, is formed from polypropylene, there is a concern that the flange portion 50 may be damaged by fluid pressure, especially hydraulic pressure. Thus, it is conceivable to form the flange portion 50 not from a single material, but from two or more materials, each with a different function. This will be explained with reference to Figure 14.

[0102] (Flange Type 2 Material) Figure 14 is a cross-sectional view showing an example of the connection between the fluid channel section 22 and the flange section 50, illustrating a modified example in which the material of the flange section 50 shown in Figure 13 has been changed. In the example shown in Figure 13, the flange section 50 was formed from a single type of material, such as polypropylene. Furthermore, it was preferable that this material be the same as the material on the inner surface of the laminate body 24.

[0103] In contrast, the flange portion 50 shown in Figure 14 is made of two types of materials. Specifically, the flange connection portion 66 is made of two types of materials. The flange connection portion 66 has a two-layer structure. The portion corresponding to the inner layer is called the inner flange connection portion 661. The portion corresponding to the outer layer is called the outer flange connection portion 662. The inner surface of the inner flange connection portion 661 faces the flange flow channel portion 67. The laminate body 24 is welded to the outer surface of the outer flange connection portion 662.

[0104] The inner flange connection portion 661 and the outer flange connection portion 662 are made of different materials. The inner flange connection portion 661 is made of the same material as the flange body 65. The outer flange connection portion 662 is made of the same material as the inner surface of the laminate body 24. By using high-strength materials to form the inner flange connection portion 661 and the flange body 65, it is possible to ensure the strength of the flange portion 50 while ensuring the welding strength between the laminate body 24 and the flange portion 50. In other words, two types of materials are used functionally. One material ensures the welding strength, and the other material ensures the overall strength of the flange portion 50.

[0105] Examples of specific materials are as follows: The material of the outer flange connection portion 662 can be the same material as the inner surface of the laminate body 24, for example, polypropylene. The material of the inner flange connection portion 661 and the flange body 65 can be a material with higher strength than the material of the outer flange connection portion 662, for example, polyphenylene sulfide. Note that the above materials are examples. To improve peel strength, the welding layer of the laminate can be made of polyethylene terephthalate, which has high material strength, and the outer flange connection portion 662 can also be made of the same material, polyethylene terephthalate. In this case, the inner flange connection portion 661 can also be made of polypropylene. The materials can be appropriately selected according to the material of the laminate body 24 and the function and strength required of the flange portion 50.

[0106] The outer flange connection portion 662 may also be formed by coating the inner flange connection portion 661 with the material that will form the outer flange connection portion 662.

[0107] In the configuration shown in Figure 14, a portion of the flange portion 50 is formed from the same material as the fluid flow channel portion 22. At least a portion of the flange portion 50 formed from the same material as the fluid flow channel portion 22 is welded to the fluid flow channel portion 22 to form at least a portion of the welded portion 80. In other words, the welded portion 80 in the flange portion 50 is formed from the same material as the fluid flow channel portion 22. At least a portion of the outer flange connection portion 662 becomes the welded portion 80 in the flange portion 50. Furthermore, in the configuration shown in Figure 14, the portion of the flange portion 50 other than the welded portion 80 can be formed from a material other than the same material as the fluid flow channel portion 22.

[0108] (Welding support member) Referring to Figure 15, a configuration for improving the strength of the welded portion 80 will be described. Figure 15 is a cross-sectional view showing an overview of the connection between the fluid flow path portion 22 and the flange portion 50, which is a modified example in which a holder 91 is added to the battery module 1 shown in Figure 13. The holder 91 is an example of a welding auxiliary member.

[0109] The holder 91 is positioned to cover the laminate 24 in the welded portion 80. The holder 91 maintains the weld between the flange portion 50 and the fluid flow channel portion 22. In other words, the holder 91 reinforces the welded portion 80.

[0110] The holder 91 can be formed from, for example, resin. The method for forming the holder 91 is not particularly limited.

[0111] The holder 91 may be a pre-molded product, for example, a cap-shaped molded product. If the holder 91 is a molded product, the holder 91 can be provided in the welded portion 80 by positioning the holder 91 in the desired position before welding the flange portion 50 and the fluid flow path portion 22, or after welding the flange portion 50 and the fluid flow path portion 22. In this case, it is preferable that the material of the holder 91 be the same as the material of the laminate 24 or the flange portion 50. In other words, it is preferable that the material of the holder 91 be the same as the material of the welded portion 80.

[0112] This allows the holder 91 to physically fix the welded portion 80, thereby offsetting the peeling load applied to the welded portion 80 by the internal pressure of the fluid passage 22, and suppressing the generation of a peeling force between the holder 91 and the welded portion 80.

[0113] Furthermore, if the holder 91 is placed before welding, the strength of the welded portion 80 can be further increased by welding at least a part of the holder 91 to the laminate body 24.

[0114] Alternatively, the holder 91 may be provided in the welded portion 80 in an unmolded resin state. In this case, the resin is cured after being provided in the welded portion 80. The curing method is not particularly limited, but UV curing can be used, for example.

[0115] The holder 91 may be provided to fill the gap in the lamination direction 1001 between the laminate body 24 at the welded portion 80 and the cell terminal portion 12 of the adjacent battery cell 10. By filling the gap between the laminate body 24 and the cell terminal portion 12 with the holder 91, the separation of the fluid flow channel portion 22 and the flange portion 50 can be further suppressed.

[0116] When the holder 91 is placed on the welded portion 80 in an unmolded resin state, it becomes easier to fill the gap between the laminate body 24 and the cell terminal portion 12 with the holder 91. This is because the holder 91 can be formed by filling the gap with uncured resin and then curing it.

[0117] (Auxiliary structure for welded part) Referring to Figures 16 and 17, other configurations for improving the strength of the welded portion 80 will be described. Figure 16 is a cross-sectional view showing a modified example in which a welded holding portion 92 is added to the battery module 1 shown in Figure 13. Figure 17 is a view of the fluid cushion 20 with the added welded holding portion 92 in the stacking direction 1001. Figure 16 corresponds to the cross-sectional view along line 1222-1222 in Figure 17. The welded holding portion 92 is an example of an auxiliary structure for the welded portion.

[0118] The welding holding portion 92 is a component that covers at least a part of the welding portion 80 and at least a part of the flange portion 50. By covering at least a part of the welding portion 80, the welding holding portion 92 holds the welding portion 80 and reinforces the welding between the flange portion 50 and the fluid flow path portion 22.

[0119] The welded holding portion 92 is a resin molded part having an overmolded structure. Overmolding means enclosing. The welded holding portion 92 holds the welded portion 80 so as to enclose at least a part of it.

[0120] The form of the welded holding portion 92 is not particularly limited. For example, as shown in Figure 17, if flange portions 50 are provided at both ends in the width direction 1003 at the end of the fluid cushion 20 in the flow direction 1002, the welded holding portion 92 may be in a form that covers the two flange portions 50 with a single component. Alternatively, the welded holding portion 92 may be in a form that covers the two flange portions 50 separately, unlike the example shown in Figure 17.

[0121] The welded holding portion 92 is a pre-formed part before being provided on the welded portion 80. The welded holding portion 92 is positioned on the welded portion 80 after the flange portion 50 and the fluid flow path portion 22 have been welded together, so as to cover at least a part of the welded portion 80. In this way, the welded holding portion 92 reinforces the welded portion 80.

[0122] The welded holding portion 92 is pre-formed into a desired shape. Therefore, the welded holding portion 92 can be positioned, for example, by fitting it into the flange portion 50. By forming the welded holding portion 92 into a shape that fits into the flange portion 50, the reinforcement of the welded portion 80 by the welded holding portion 92 can be made stronger.

[0123] The material used to form the welded holding portion 92 is not particularly limited. For example, the welded holding portion 92 can be formed using a thermosetting resin or the like.

[0124] (Surface roughness of the flange) As described above, the flange portion 50 and the fluid flow channel portion 22 are fixed by welding. In the flange portion 50, it is preferable that the surface of the portion welded to the fluid flow channel portion 22 has a rougher surface than the surface of other parts of the flange portion 50. For example, in the configuration shown in Figure 13 described earlier, the surface roughness of the outer surface of the flange connection portion 66 is made rougher than, for example, the surface roughness of the flange body 65. Also, for example, in the configuration shown in Figure 14 described earlier, the surface roughness of the outer surface of the outer flange connection portion 662 is made rougher than, for example, the surface roughness of the flange body 65.

[0125] In this way, the surface roughness of the portion of the flange 50 that is welded to the fluid flow channel 22 is made rough. This makes it possible to strengthen the welding between the flange 50 and the fluid flow channel 22. This is because the contact area between the flange 50 and the fluid flow channel 22 can be increased.

[0126] The method for roughening the surface is not particularly limited. For example, the surface can be roughened by blasting.

[0127] (Flange holding part) The flange retaining portion 5 will be described with reference to Figure 13. Figure 13 shows the flange-side end 101 of the battery cell 10. The flange-side end 101 is the end of the battery cell 10 that faces the flange portion 50 in the flow direction 1002. Also, Figure 13 shows the cell-side end 501 of the flange portion 50. The cell-side end 501 is the end of the flange portion 50 that faces the battery cell 10 in the flow direction 1002. The portion between the flange-side end 101 and the cell-side end 501 in the flow direction 1002 is called the flange retaining portion 5. The flange retaining portion 5 is the portion in the fluid flow path 22 that is continuous with the welded portion 80 and does not come into contact with the battery cell 10. The length of the flange retaining portion 5 in the flow direction 1002 is called the clearance 1401.

[0128] The clearance 1401 is preferably of an appropriate length, and in particular, as short as possible. Shortening the clearance 1401 makes it easier to ensure the strength of the fluid flow channel 22 in the flange holding portion 5.

[0129] An internal pressure 1331 is generated in the fluid passage. In the flange holding portion 5, there are no components such as battery cells 10 that come into contact with the laminate 24 on the outside in the stacking direction 1001 of the laminate 24. Therefore, if the clearance 1401 is long, the laminate 24 may not be able to withstand the internal pressure 1331 and may break. To address this, the clearance 1401 is optimized by adjusting the shape of the flange portion 50. By shortening and optimizing the clearance 1401, it becomes easier to ensure the strength of the fluid passage portion 22 in the flange holding portion 5.

[0130] (Flow rate control) Referring to Figure 18, the fluid flow at the end of the battery module in the flow direction 1002 will be explained. Figure 18 shows an example of how the flange portions 50 are stacked at the end of the battery module in the flow direction 1002.

[0131] At the end of the battery module, the flange portions 50 are stacked in the stacking direction 1001. An end flow channel 68 is formed inside the stacked flange portions 50. The end flow channel 68 is formed when the flow channels inside each flange portion 50 are connected to each other as the stacked flange portions 50 are connected. Fluid that has flowed through the flange flow channel portion 67 of each flange portion 50 flows into the end flow channel 68.

[0132] Figure 18 shows the pre-confluence flow direction 1411 and the post-confluence flow direction 1412. The pre-confluence flow direction 1411 is the direction in which the fluid flows in the flange channel section 67. The post-confluence flow direction 1412 is the direction in which the fluid flows in the end channel section 68. In the example shown in Figure 18, the end channel section 68 extends along the stacking direction 1001. The post-confluence flow direction 1412 extends in a direction intersecting the direction in which the flange channel section 67 extends.

[0133] Note that the forward flow direction 1411 and the backward flow direction 1412 of the confluence in Figure 18 show the fluid flow when the fluid flows out of the fluid cushion. When the fluid flows into the fluid cushion, the direction of the fluid flow is opposite to the direction shown by the forward flow direction 1411 and the backward flow direction 1412 of the confluence.

[0134] Furthermore, when stacking the flange portions 50, an O-ring 69 may be placed between the flange portions 50.

[0135] (Power unit) Figure 19 is an exploded perspective view of a power unit 1500, showing an example of a power unit 1500 incorporating a battery module 1. In the example shown in Figure 19, the power unit 1500 comprises two battery modules 1. The power unit 1500 is formed by sandwiching and fixing the battery modules 1 from both sides with plate-shaped members in the stacking direction 1001, the flow direction 1002, and the width direction 1003.

[0136] The four side plate-like members 1511 shown in Figure 19 are members that sandwich the battery module 1 in the stacking direction 1001 and the flow direction 1002. The bottom plate-like member 1521 and the top plate-like member 1522 are members that sandwich the battery module 1 in the width direction 1003. The bottom plate-like member 1521 is in contact with a water jacket (not shown) which serves as a cooling circuit located on its underside. The cooling circuit is a component that cools the battery module 1 and the like. The bottom plate-like member 1521 is positioned opposite the top plate-like member 1522 and functions as a bottom plate-like member.

[0137] In Figure 19, the flange portion 50 is depicted in a simplified form, showing multiple flanges stacked on top of each other.

[0138] Figure 19 shows the back internal flow direction 1421 and the module end flow direction 1422. The back internal flow direction 1421 is the direction in which the fluid flows within the fluid flow channel section 22. The module end flow direction 1422 is the direction in which the fluid flows at the end of the battery module 1, for example, through the cushion connection section 1531. The back internal flow direction 1421 is the direction along the flow channel direction 1002. The module end flow direction 1422 is the direction along the stacking direction 1001. The back internal flow direction 1421 in Figure 19 corresponds to the pre-confluence flow direction 1411 in Figure 18. The module end flow direction 1422 in Figure 19 corresponds to the post-confluence flow direction 1412 in Figure 18.

[0139] (Relationship with the vehicle body) Referring to Figure 20, the coordination between the power unit 1500 and the fluid tank 2010 and other components provided in the vehicle body 2000 will be explained. Figure 20 is a diagram showing the fluid flow between the power unit 1500 and the vehicle body 2000. As shown in Figure 20, the vehicle body 2000 includes a fluid tank 2010, a safety relief valve 2011, a compressor 2012, and a control unit 2050.

[0140] The fluid tank 2010 is a tank that stores the fluid flowing through the fluid cushion 20. The fluid may be either a gas or a liquid. If the fluid is a gas, the fluid tank 2010 is called a gas tank. If the gas is air, the gas tank is called an air tank. If the fluid is a liquid, the fluid tank 2010 is called a liquid tank. The fluid tank 2010 is connected to each fluid cushion 20 via the tank line 2021.

[0141] The safety relief valve 2011 is a relief valve designed to reduce the internal pressure of the fluid tank 2010, for example, when the internal pressure rises to a dangerous level. The safety relief valve 2011 is installed in the fluid tank 2010.

[0142] Compressor 2012, or compressor, is a device for increasing the internal pressure of fluid tank 2010. When the fluid is a liquid, compressor 2012 is configured as a water pump. Compressor 2012 is connected to fluid tank 2010 via compressor line 2022.

[0143] The control unit 2050 controls various parts of the vehicle body 2000. The control unit 2050 may also determine the charge status of the battery cell 10.

[0144] The control unit 2050 receives detection results from detection devices such as sensors. The control unit 2050 also controls the operation of various parts, such as the compressor 2012 and valves installed in the lines connecting these parts.

[0145] Figure 20 shows the cushion inflow direction 1431 and the cushion outflow direction 1432. The cushion inflow direction 1431 is the direction in which fluid flows from the fluid tank 2010 towards the fluid cushion 20. The cushion outflow direction 1432 is the direction in which fluid flows out from the fluid cushion 20 towards the fluid tank 2010.

[0146] For example, when the battery cell 10 is charged and its volume increases, the fluid flows from the fluid cushion 20 towards the fluid tank 2010 to reduce the volume of the fluid cushion 20. In other words, the fluid flows in the direction of cushion outflow 1432.

[0147] In contrast, if, for example, the battery cell 10 discharges and its volume decreases, the fluid flows from the fluid tank 2010 towards the fluid cushion 20 in order to increase the volume of the fluid cushion 20. In other words, the fluid flows in the direction of cushion inflow 1431.

[0148] Furthermore, Figure 20 shows the tank pressurization direction 1433. The tank pressurization direction 1433 indicates that the fluid in the fluid tank 2010 is pressurized via the compressor line 2022 when the compressor 2012 is activated. As mentioned above, when the fluid is a liquid, the compressor 2012 is configured as a water pump. When the fluid is a liquid, the tank pressurization direction 1433 indicates that the fluid in the fluid tank 2010 is pressurized by the water pump.

[0149] Even if the operation of the compressor 2012 causes the battery cell 10 to expand or contract, and consequently the fluid cushion 20 to expand or contract, it becomes easier to maintain, for example, the internal pressure of the fluid cushion 20 at a uniform pressure. The compressor 2012 may also operate to maintain the internal pressure of the fluid tank 2010 at a uniform pressure.

[0150] (Battery cell charge status) The detection of the State of Charge (SOC) of the battery cell 10 will be explained with reference to Figure 21. Figure 21 shows a power unit 1500 in which a pressure sensor 1510 is further provided in addition to the power unit 1500 shown in Figure 20. As explained earlier, the volume of the battery cell 10 changes according to the charge and discharge state of the battery cell 10. When the volume of the battery cell 10 changes, the pressure between the battery cell 10 and the fluid cushion 20 changes. Normally, when the volume of the battery cell 10 increases, the pressure between the battery cell 10 and the fluid cushion 20 increases. Conversely, when the volume of the battery cell 10 decreases, the pressure between the battery cell 10 and the fluid cushion 20 decreases. Therefore, a pressure sensor 1510 is provided between the battery cell 10 and the fluid cushion 20. The control unit 2050 and the like can determine the charge state of the battery cell 10 by the pressure detected by the pressure sensor 1510.

[0151] In the example shown in Figure 21, one pressure sensor 1510 is provided in the power unit 1500. However, the number of pressure sensors 1510 provided in the power unit 1500 is not limited to one. The pressure sensors 1510 may be provided, for example, between multiple battery cells 10 and fluid cushions 20. Alternatively, multiple pressure sensors 1510 may be provided between the battery cells 10 and fluid cushions 20 at different positions in at least one of the flow path direction 1002 and the width direction 1003.

[0152] Based on the pressure detected by the pressure sensor 1510, the charge status of the battery cell 10 can be determined. Furthermore, based on the detected pressure, the fluid exchange between the fluid cushion 20 and the fluid tank 2010 can be controlled. Additionally, based on the detected pressure, the operation of the compressor 2012 can be controlled.

[0153] (Condition of the fluid tank) The detection of the charge state of the battery cell 10 via the fluid tank 2010 will be described with reference to Figure 22. Figure 22 shows a vehicle body 2000 in which a tank sensor unit 2031 is further provided in addition to the vehicle body 2000 shown in Figure 21. The tank sensor unit 2031 can be, for example, a sensor that detects the volume of the fluid tank 2010.

[0154] The volume of the fluid tank 2010 changes according to the charge and discharge state of the battery cell 10. As explained earlier, when the battery cell 10 is charged, a flow in the cushion outflow direction 1432 is generated in the tank line 2021. As a result, the volume of the fluid tank 2010 increases. Conversely, when the battery cell 10 is discharged, a flow in the cushion inflow direction 1431 is generated in the tank line 2021. As a result, the volume of the fluid tank 2010 decreases.

[0155] Therefore, the tank sensor unit 2031 detects the volume of the fluid tank 2010. In other words, the tank sensor unit 2031 detects at least one of the expansion and contraction of the fluid tank 2010. In particular, when the compressor 2012 is not provided, or when the compressor 2012 is not operating, the charge state of the battery cell 10 can be determined based on the volume of the fluid tank 2010 detected by the tank sensor unit 2031.

[0156] By combining the detection results from the pressure sensor 1510 with the detection results from the tank sensor unit 2031 to determine the charge status of the battery cell 10, a more accurate determination of the charge status becomes possible.

[0157] Furthermore, if the tank sensor unit 2031 is provided, the pressure sensor 1510 does not necessarily have to be provided. This is because it is possible to determine the charge state of the battery cell 10 based solely on the detection result of the tank sensor unit 2031.

[0158] Furthermore, the tank sensor unit 2031 is not limited to being a sensor that detects changes in the volume of the fluid tank 2010. For example, the tank sensor unit 2031 may be configured to detect the internal pressure of the fluid tank 2010, or the direction of the fluid flowing through the tank line 2021. The charge state of the battery cell 10 can also be determined by the internal pressure of the fluid tank 2010 and the direction of the fluid in the tank line 2021.

[0159] Furthermore, when detecting the direction of the fluid flowing through tank line 2021, the detection device can be installed in tank line 2021. In other words, the device for detecting the direction of the fluid flowing through tank line 2021 does not necessarily have to be installed in fluid tank 2010.

[0160] (Water jacket) The water jacket 1550 will be described with reference to Figures 23 and 24. Figure 23 shows a power unit 1500 in which the water jacket 1550 is further added to the power unit 1500 shown in Figure 20. Figure 24 shows a power unit 1500 in which the water jacket 1550 is omitted from the power unit 1500 shown in Figure 23.

[0161] The water jacket 1550 is provided to cool the battery cells 10 and the like, as previously explained with reference to Figure 19. The water jacket 1550 is positioned, for example, branching off from the vehicle's cooling channel. This allows the water jacket 1550 to cool the battery cells 10 as part of the vehicle's cooling system. The vehicle's cooling system will be explained later.

[0162] Incidentally, the battery module 1 of this embodiment includes a fluid cushion 20. A fluid flows inside the fluid cushion 20. Here, if the fluid is a liquid, the fluid cushion 20 can perform at least part of the function of the water jacket 1550. In addition to mitigating the effects of volume changes in the battery cells 10, the fluid cushion 20 can cool the battery cells 10. This can reduce the load on the vehicle's cooling system.

[0163] Furthermore, since the fluid cushion 20 performs at least part of the function of the water jacket 1550, the water jacket 1550 can be omitted, as shown in Figure 24.

[0164] (Vehicle cooling system) The vehicle cooling system 3000 will be described with reference to Figure 25. Figure 25 is a diagram illustrating an overview of an example of the vehicle cooling system 3000. The cooling system 3000 comprises a vehicle cooling passage 3001, a radiator 3010, and a water pump 3020. The vehicle cooling passage 3001 is a passage through which a cooling liquid flows. Figure 25 shows the flow direction 3002 of the passage. The flow direction 3002 is the direction in which the liquid flows in the vehicle cooling passage 3001.

[0165] A cooling device is connected to the vehicle cooling channel 3001. The cooling device is a device that is cooled by the liquid flowing through the vehicle cooling channel 3001. Figure 25 illustrates five cooling devices: the first cooling device 3031, the second cooling device 3032, the third cooling device 3033, the fourth cooling device 3034, and the fifth cooling device 3035.

[0166] Examples of devices that require cooling include motors, transmissions, and batteries.

[0167] The device to be cooled is connected to the vehicle cooling passage 3001. In other words, the device to be cooled branches off from the vehicle cooling passage 3001.

[0168] The cooling devices are connected to the vehicle cooling channel 3001 in various ways. Examples of connection configurations include the following: The first cooling device 3031 and the second cooling device 3032 are connected to a bypass channel 3003, which is a channel formed to bypass the vehicle cooling channel 3001. Alternatively, the first cooling device 3031 and the second cooling device 3032 are arranged in series in the bypass channel 3003.

[0169] The third cooled device 3033 is directly connected to the vehicle cooling channel 3001. The fourth cooled device 3034 and the fifth cooled device 3035 are connected to the vehicle cooling channel 3001 in parallel. Note that the configuration in which the cooled devices are connected to the vehicle cooling channel 3001 is not limited to the example shown in Figure 25.

[0170] Furthermore, a valve may be provided in at least one of the parts where the vehicle cooling passage 3001 branches off and the part upstream of the device being cooled. By adjusting the valve, the flow rate of the liquid flowing through the vehicle cooling passage 3001, and consequently the flow rate of the liquid flowing to the device being cooled, can be adjusted.

[0171] If the battery module 1 of this embodiment is equipped with a water jacket 1550, the water jacket 1550 (cooling circuit located on the underside of plate 1521) may be connected to the vehicle cooling passage 3001 as a device to be cooled.

[0172] In the battery module 1 of this embodiment, the fluid flowing through the vehicle cooling channel 3001 may flow through the fluid cushion 20. Here, a plurality of fluid cushions 20 and their corresponding cushion connecting parts 1531 are collectively referred to as a pressurized structure. The pressurized structure may branch off from the vehicle cooling channel 3001. In other words, the pressurized structure may be connected to the vehicle cooling channel 3001. This allows the liquid in the vehicle cooling channel 3001 to flow through the fluid cushion 20.

[0173] Furthermore, in the battery module 1 of this embodiment, the pressurizing structure may be a branch of the vehicle cooling channel 3001, which is provided with the water jacket 1550. In other words, the pressurizing structure may be provided in the vehicle cooling channel 3001 that flows liquid into the water jacket 1550. For example, in the example shown in Figure 25, either the first cooled device 3031 or the second cooled device 3032 may be the pressurizing structure, and the other may be the water jacket 1550.

[0174] In this embodiment, the battery module can be positioned using the four corners of the flange, making it easy to adjust the pressurized range and thus stabilizing battery performance. Furthermore, by setting fluid flow paths in the corners of the flange, the volumetric energy density of the battery module can be maximized.

[0175] Furthermore, in the battery module of this embodiment, the shape of the flange portion allows for the adjustment of the appropriate clearance between the portion to be pressurized within the battery cell stack and the portion that fixes each component, in accordance with the shape of the surrounding components such as the battery cells. As a result, the durability of the fluid cushion, particularly the fluid flow path portion, can be improved. In addition, the strength of the welded portion can be improved by the use of auxiliary members or auxiliary structures.

[0176] Furthermore, in the battery module of this embodiment, when assembling the battery cell stack, if the battery cells and fluid cushion are stacked alternately, the alignment of the tab leads of the battery cells with the busbars of the battery module becomes easier at the flange portion, improving assembly efficiency. Also, stacking via the flange portion makes assembly easier without the use of special height adjustment jigs.

[0177] The embodiments of the present invention have been described above. The present invention is not limited to the embodiments described above, and various modifications, variations, and combinations are possible. [Explanation of Symbols]

[0178] 1 Battery Module 10 battery cells 20 Fluid cushions 100 Battery Cell Stack 110 End Plate 2010 Fluid Tank 2012 Compressor 2050 Control Unit

Claims

1. A battery cell stack in which multiple battery cells are stacked, A pair of end plates provided at both ends of the stacking direction of the battery cell stack, The battery comprises stacked battery cells and a fluid cushion disposed between the battery cells, A fluid tank connected to the aforementioned fluid cushion, A compressor connected to the aforementioned fluid tank, The control unit further comprises, The control unit controls the operation of the compressor so that the pressure within the fluid cushion becomes uniform in response to at least one of the expansion and contraction of the fluid cushion. Battery module.

2. The fluid contained in the aforementioned fluid cushion is a liquid. A liquid tank, which serves as a fluid tank, is connected to the aforementioned fluid cushion, A water pump, which acts as a compressor, is connected to the aforementioned fluid tank. The control unit further comprises, The control unit controls the operation of the compressor so that the pressure within the fluid cushion becomes uniform in response to at least one of the expansion and contraction of the fluid cushion. The battery module according to claim 1.

3. The fluid contained in the aforementioned fluid cushion is a gas. An air tank, which serves as a fluid tank, is connected to the aforementioned fluid cushion, A compressor connected to the aforementioned air tank, The control unit further comprises, The control unit controls the operation of the compressor so that the pressure within the fluid cushion becomes uniform in response to at least one of the expansion and contraction of the fluid cushion. The battery module according to claim 1.

4. The fluid contained in the aforementioned fluid cushion is a liquid. The battery cell is cooled by the fluid cushion. The battery module according to claim 1 or 2.

5. The fluid contained in the aforementioned fluid cushion is a liquid. The system further comprises a cushion connecting portion that connects the aforementioned fluid cushions, The fluid cushion and the cushion connecting portion together are defined as a pressurized structure. The pressurized structure branches the vehicle cooling passage of the vehicle on which the battery cell is mounted. The battery module according to claim 1 or 2.

6. The pressurized structure branches the vehicle cooling channel through the water jacket that cools the battery cell stack, The battery module according to claim 5.

7. The tank sensor unit further comprises a unit that detects at least one of the expansion and contraction of the fluid tank. The control unit determines the charge state of the battery cell based on the results detected by the tank sensor unit. The battery module according to claim 2 or 3.

8. The fluid cushion includes a cell fixing portion for positioning adjacent battery cells in the stacking direction. The battery module according to claim 1 or 2.

9. The fluid cushion comprises a flange portion, The flange portion includes a recess, which has a shape that conforms to the shape of the end of the battery cell, as the cell fixing portion. The battery module according to claim 8.

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