Battery pack

Abstract

The present invention provides a battery pack equipped with a water jacket that can reduce temperature variations between multiple cell stacks. [Solution] The battery pack 1 comprises a plurality of battery modules 30, a battery case 10, and a water jacket 50. The plurality of battery modules 30 include a right-side battery module group 30R and a left-side battery module group 30L. The water jacket 50 has a branching section 56 that branches from an inlet 53 into a main flow 60 and a branch flow 70. Coolant flows through the main flow 60 in the order of the right-side battery module group 30R and then the left-side battery module group 30L, and coolant flows through the branch flow 70 in the order of the left-side battery module group 30L and then the right-side battery module group 30R.

Description

Technical Field

[0001] The present invention relates to a battery pack mounted on an electric vehicle or the like.

Background Art

[0002] In recent years, in order to enable more people to access affordable, reliable, sustainable, and advanced energy, research and development have been conducted on secondary batteries that contribute to energy efficiency.

[0003] High-output and large-capacity batteries are mounted on electric vehicles such as battery electric vehicles, plug-in hybrid vehicles, and fuel cell vehicles. Since the battery mounted on an electric vehicle generates a large amount of heat during charging and discharging, a cooling mechanism for cooling the battery is provided from the viewpoints of safety and prevention of battery deterioration.

[0004] For example, Patent Document 1 describes a cooling device provided below a heating element such as a battery and electronic components. The cooling device includes a metal cooling panel for cooling the heating element and a resin flow path joined to the metal cooling panel and for flowing a refrigerant. The resin flow path includes a first flow path unit and a second flow path unit. The flow path through which the refrigerant flowing in from the refrigerant inlet flows is branched at the refrigerant branch port into a flow path for guiding the refrigerant across the entire first flow path unit and a flow path for guiding the refrigerant from the first flow path unit to the second flow path unit.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the cooling device described in Patent Document 1, there was room for improvement because there could be large temperature variations between the heating element located upstream in the refrigerant flow direction in the first or second flow path unit and the heating element being cooled downstream.

[0007] The present invention provides a battery pack equipped with a water jacket that can reduce temperature variations between multiple cell stacks. [Means for solving the problem]

[0008] The present invention Multiple cell stacks, in which multiple battery cells are stacked, A battery case housing the aforementioned cell stack, A battery pack comprising a water jacket provided below the cell stack, through which a refrigerant for regulating the temperature of the cell stack flows, The plurality of cell stacks include a first cell stack group provided on one side in a predetermined direction and a second cell stack group provided on the other side. The water jacket has a branching section that branches from the inlet into at least a first channel and a second channel, The refrigerant flows through the first flow path in the order of the first cell stack group and the second cell stack group. The refrigerant flows through the second flow path in the order of the second cell stack group and the first cell stack group. [Effects of the Invention]

[0009] According to the present invention, temperature variations between multiple cell stacks can be reduced. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a perspective view of the battery pack 1 of the first embodiment, showing the case cover 12 removed from the case body 11. [Figure 2] Figure 2 is an exploded perspective view of the battery pack 1 of the first embodiment. [Figure 3] Figure 3 is a top view of a plurality of battery modules 30 housed in the case body 11. [Figure 4] Figure 4 is a front view of the battery cell 31. [Figure 5] Figure 5 shows a top view of the water jacket 50. [Figure 6] Figure 6 shows the flow path of the refrigerant in the water jacket 50. [Figure 7] Figure 7 is an enlarged top view of the branch portion 56. [Figure 8] Figure 8 is an enlarged top view of the corner region 66 on the rear end side of the main flow 60. [Figure 9] Figure 9 is a top view of a modified water jacket 50. [Figure 10] Figure 10 is a perspective view of the battery pack 2 according to the second embodiment, showing a state where the case cover 12 is removed from the case body 11. [Figure 11] Figure 11 is an exploded perspective view of the battery pack 2. [Figure 12] Figure 12 is a perspective view of the upper case body 20, the water jacket 50, and the upper water jacket 80. [Figure 13] Figure 13 shows the flow path of the refrigerant in the water jacket 50 and the upper water jacket 80. [Figure 14] Figure 14 is an enlarged perspective view of the portion surrounded by the two-dot chain line in FIG. 13. [Figure 15] Figure 15 is a cross-sectional view of the communication flow path 85 that connects the water jacket 50 and the upper water jacket 80. [Figure 16] (a) of Figure 16 is a perspective view of the upper end portion of the pipe member 86 provided with the rubber mount 91, and (b) of Figure 16 is a cross-sectional view thereof.

Embodiments for Carrying Out the Invention

[0011] Hereinafter, each embodiment of the battery pack of the present invention will be described based on the accompanying drawings. The drawings are to be viewed in the direction of the reference numerals. Also, in this specification and the like, for the sake of simplicity and clarity of explanation, in the drawings, the front of the vehicle is shown as Fr, the rear as Rr, the left as L, the right as R, the upper as U, and the lower as D.

[0012] [First Embodiment] FIG. 1 is a perspective view of the battery pack 1 of the first embodiment, showing a state in which the case cover 12 is removed from the case body 11. FIG. 2 is an exploded perspective view of the battery pack 1 of the first embodiment.

[0013] The battery pack 1 is attached to, for example, an electric vehicle such as a battery - powered electric vehicle, a plug - in hybrid vehicle, or a fuel - cell vehicle, and stores electric power to be supplied to a motor or the like that serves as a drive source of the electric vehicle. The battery pack 1 is attached under the floor of the electric vehicle.

[0014] The battery pack 1 includes a battery case 10 including a case body 11 and a case cover 12, a plurality of battery modules 30 housed in the battery case 10, an electric connection box 40 housed in the battery case 10 with various electrical components installed inside, a water jacket 50 provided below the battery modules 30 through which a refrigerant for adjusting the temperature of the battery modules 30 circulates, and an under - cover 19 formed of a heat - insulating material that covers the battery case 10 and the water jacket 50 from below.

[0015] The case body 11 of the battery case 10 has a bottom portion 13 and a side wall portion 14 surrounding the periphery of the bottom portion 13, and is configured in a tray shape. The case cover 12 covers the case body 11 in which the battery modules 30 and the electric connection box 40 and the like are housed from above via a sealing material 18, and seals the inside of the battery pack 1. Also, a plurality of cross - members 15 extending in the left - right direction are provided on the case body 11.

[0016] The case body 11 is formed from, for example, an aluminum alloy containing aluminum. Specifically, the case body 11 is formed by aluminum die casting. Aluminum die casting is formed by melting an aluminum alloy, filling it into a mold at high speed using a die casting machine, and then applying high pressure. By forming the case body 11 from an aluminum alloy, the weight of the battery pack 1 can be reduced.

[0017] The case body 11 has a pair of side frames 16 attached to both the left and right ends. The battery pack 1 is fixed to the body of the electric vehicle via the side frames 16.

[0018] Each battery module 30 has a roughly rectangular parallelepiped shape and is housed in the case body 11 with its longitudinal direction oriented left to right. In the first embodiment, thirteen battery modules 30 are placed on the upper surface 13a of the bottom 13 of the case body 11. Specifically, the battery modules 30 are arranged in two rows in the left-right direction. Seven battery modules 30 are arranged in the front-to-back direction in the right row, and six battery modules 30 are arranged in the front-to-back direction in the left row. A cross member 15 is provided between adjacent battery modules 30 in the front-to-back direction. Adjacent battery modules 30 are electrically connected to each other via busbars. The number and arrangement of the battery modules 30 can be arbitrarily set and are not limited to the example shown.

[0019] Figure 3 is a top view of multiple battery modules 30 housed in the case body 11. Each battery module 30 is composed of multiple battery cells 31 (dashed lines) stacked on top of each other. The battery cells 31 of each battery module 30 are stacked in the front-to-back direction. The battery cells 31 are, for example, lithium-ion batteries or nickel-metal hydride batteries.

[0020] Figure 4 is a front view of a battery cell 31. The battery cell 31 is, for example, a pouch-type cell. The battery cell 31 includes a positive electrode layer, a negative electrode layer, an electrolyte placed between the positive electrode layer and the negative electrode layer, and an outer casing 32 that houses these components. Each of the positive electrode layer and the negative electrode layer is provided with a terminal portion 33 exposed from the outer casing 32. Multiple battery cells 31 are electrically connected to each other via busbars 45 at the terminal portions 33. Note that the battery cell 31 is not limited to a pouch-type cell, but may also be, for example, a prismatic cell. Also, detailed illustrations of the terminal portion 33 are omitted in all figures except Figure 4.

[0021] The battery cell 31 has an elongated shape, and terminal portions 33 are provided at both ends in the longitudinal direction. When housed in the battery case 10, the battery cell 31 is arranged so that its longitudinal direction is left to right.

[0022] In the battery cell 31, the terminal region A1, where the terminal portion 33 is provided, is a region that generates a lot of heat in the longitudinal direction (left-right direction), while the central region A2 between the terminal portions 33 generates less heat than the terminal region A1. In Figure 3, the terminal region A1 is shown as the area enclosed by the dashed line.

[0023] Returning to Figures 1 and 2, there are two electrical junction boxes 40, one located near the front end and the other near the rear end of the battery pack 1. The electrical junction box 40 located near the front end of the battery pack 1 is positioned to straddle the top of the two battery modules 30 located in the front row. The electrical junction box 40 located near the rear end of the battery pack 1 is positioned on top of the battery module 30 located in the last row of the rightmost column. These two electrical junction boxes 40 are connected by high-voltage power lines (e.g., cables or busbars) not shown.

[0024] The electrical connection box 40 is equipped with, for example, power input / output circuits for the battery module 30, power input / output circuits for the drive unit mounted on the electric vehicle, power input / output circuits for the charger, power input / output circuits for auxiliary equipment, and a circuit breaker for cutting off power to the battery pack 1 in case of an abnormality.

[0025] The water jacket 50 is located in a space partitioned between a cover plate 51 located below the case body 11 and the lower surface 13b of the bottom 13 of the case body 11. A coolant (e.g., cooling water) flows through the water jacket 50, and the water jacket 50 cools the battery module 30 with the flowing coolant. The water jacket 50 can also heat the battery module 30 by preheating the flowing coolant using a heater (not shown) or the like. In this way, the water jacket 50 cools or heats the battery module 30 to regulate its temperature.

[0026] The cover plate 51 is joined to the lower surface 13b of the case body 11, for example, by friction stir welding (FSW). More specifically, the lower surface 13b of the case body 11 and the cover plate 51 each have irregularities. The lower surface 13b of the case body 11 has protrusions that project toward the cover plate 51 and recesses that are recessed on the opposite side of the protrusions from the cover plate 51, and the cover plate 51 has protrusions that project toward the case body 11 and recesses that are recessed on the opposite side of the protrusions from the case body 11. Friction stir welding is performed along the protrusions with the protrusions on the lower surface 13b of the case body 11 and the cover plate 51 in contact with each other. This creates a refrigerant flow path 55 in the water jacket 50. Note that either the lower surface 13b of the case body 11 or the cover plate 51 may be a flat surface without irregularities.

[0027] Since the water jacket 50 is provided on the lower surface 13b side of the bottom 13 of the case body 11, even if the water jacket 50 is damaged due to a collision with an electric vehicle or the like and refrigerant leaks out, it is possible to prevent the refrigerant from coming into contact with the battery module 30 housed in the case body 11.

[0028] Figure 5 shows a top view of the water jacket 50. Figure 6 shows the refrigerant flow path in the water jacket 50.

[0029] The water jacket 50 has an inlet 53 and an outlet 54 located in the center of the front end in the left-right direction, and a refrigerant flow path 55 through which the refrigerant flows. The inlet 53 is located slightly to the right in the center in the left-right direction, and the outlet 54 is located slightly to the left in the center in the left-right direction. The refrigerant is supplied to the water jacket 50 from the inlet 53, flows through the refrigerant flow path 55, and is discharged to the outside of the water jacket 50 from the outlet 54.

[0030] The water jacket 50 has a branch section 56 that branches off from the inlet 53 into two flow paths. The branch section 56 is located near the inlet 53 in the refrigerant flow path 55. These two flow paths include a main flow 60 provided along the terminal area A1 of each battery module 30 and a branch flow 70 provided along the central area A2 of each battery module 30. The main flow 60 and the branch flow 70 constitute the aforementioned refrigerant flow path 55. In Figure 6, the main flow 60 is shown by a thick solid arrow, and the branch flow 70 is shown by a thick dashed-dotted arrow.

[0031] The main stream 60 and tributary stream 70 of the water jacket 50 will be described in detail below. In the following description, among the multiple battery modules 30, the battery modules 30 located on the right side of the battery case 10 will be referred to as the right battery module group 30R, and the battery modules 30 located on the left side will be referred to as the left battery module group 30L (see Figure 3).

[0032] In the main flow 60, the refrigerant flows in the order of the right battery module group 30R, then the left battery module group 30L. More specifically, in the main flow 60, the refrigerant flows in the order of the right terminal area A1 of the right battery module group 30R (from front to back), the left terminal area A1 of the right battery module group 30R (from back to front), the right terminal area A1 of the left battery module group 30L (from front to back), and the left terminal area A1 of the left battery module group 30L (from back to front). In other words, the main flow 60 forms a meandering flow path along the terminal areas A1 of the left battery module group 30L and the right battery module group 30R, thereby regulating the temperature of the battery modules 30.

[0033] The main flow 60 has another branch 61 located downstream of the branch 56 in the flow direction. The branch 61 is located at the right front end of the water jacket 50 and further branches the main flow 60 into two channels. These two channels include an outer main flow 62 located along the outer edge of the water jacket 50, and an inner main flow 63 located inside the outer main flow 62 and along the outer main flow 62. The inner main flow 63 is located closer to the central region A2 of the terminal region A1 of each battery module 30 than the outer main flow 62.

[0034] Since the main flow 60 branches into an outer main flow 62 and an inner main flow 63, even if an object collides with the bottom surface of the battery pack 1 and the outer main flow 62 (or inner main flow 63) of the water jacket 50 becomes blocked, the flow of refrigerant in the main flow 60 can be maintained through the inner main flow 63 (or outer main flow 62).

[0035] The main flow 60 has a confluence section 64 where the outer main flow 62 and the inner main flow 63 merge. The confluence section 64 is located near the outlet 54. The confluence section 64 combines the refrigerant that has flowed through the outer main flow 62 and the inner main flow 63 and discharges it to the outside of the water jacket 50 from the outlet 54.

[0036] It is preferable that the branch section 61 and the merging section 64 are provided on the upstream side of the main flow 60 (closer to the inlet 53) and the downstream side of the main flow 60 (closer to the outlet 54), respectively. This enhances the effect of maintaining the flow of refrigerant in the main flow 60 even if either the outer main flow 62 or the inner main flow 63 becomes blocked.

[0037] The branch stream 70 is provided along the central region A2 of each battery module 30 and is located inside the main stream 60 which is provided along the terminal region A1 of each battery module 30.

[0038] Refrigerant flows through the branch 70 in the order of the left battery module group 30L and the right battery module group 30R. Specifically, the branch 70 has a left branch 71 provided along the central region A2 of the left battery module group 30L, and a right branch 72 provided downstream of the left branch 71 in the flow direction and provided along the central region A2 of the right battery module group 30R. The left branch 71 allows the refrigerant branched from the branching section 56 to flow towards the rear, then turns back at the rear end and flows towards the front. The left branch 71 and the right branch 72 are in communication at the front end of the water jacket 50. The right branch 72 allows the refrigerant that has flowed from the left branch 71 to flow towards the rear, then turns back at the rear end and flows towards the front.

[0039] The tributary 70 is located at the downstream end of the right-side tributary 72 and has a confluence section 73 where it joins the main stream 60. More specifically, the confluence section 73 joins the inner main stream 63 of the main stream 60. Since the tributary 70 joins the inner main stream 63, the channel structure can be simplified.

[0040] As described above, the water jacket 50 has a branch section 56, and the refrigerant flow path 55 of the water jacket 50 branches into a main flow 60 that regulates the temperature of the terminal region A1 of each battery module 30 and a branch flow 70 that regulates the temperature of the central region A2 of each battery module 30. Therefore, since the terminal region A1 and the central region A2 of each battery module 30 are temperature-regulated by separate flow paths, the temperature of each battery module 30 can be effectively regulated.

[0041] Furthermore, in the main flow 60, the refrigerant flows through the right battery module group 30R and then the left battery module group 30L, while in the branch flow 70, the refrigerant flows through the left battery module group 30L and then the right battery module group 30R. As a result, the refrigerant flowing through the main flow 60 and the refrigerant flowing through the branch flow 70 form a counterflow. Therefore, temperature variations between the right battery module group 30R and the left battery module group 30L are reduced, and the temperatures of the multiple battery modules 30 can be made more uniform.

[0042] The battery pack 1 can reduce temperature variations among multiple battery modules 30, thereby improving the temperature regulation performance of the battery modules 30. As a result, the performance of the battery modules 30 can be improved, and their degradation can be suppressed.

[0043] Figure 7 is an enlarged top view of the branch section 56. The branch section 56 is provided with a throttling structure 57 that reduces the flow rate of refrigerant flowing into the branch 70. The throttling structure 57 creates a flow rate difference between the refrigerant flowing through the main flow 60 and the branch 70. Specifically, the throttling structure 57 has the function of reducing the flow rate of refrigerant flowing into the branch 70 and adjusting the flow rate so that the flow rate of refrigerant flowing into the main flow 60 is greater than that of the branch 70.

[0044] The diaphragm structure 57 has a structure that narrows the flow path width at the connection point between the branch 56 and the tributary 70 compared to the flow path width at the connection point between the branch 56 and the main stream 60. Specifically, the diaphragm structure 57 is configured by narrowing the flow path width in the horizontal direction and / or by narrowing the flow path width in the vertical direction. More specifically, the diaphragm structure 57 is configured by narrowing the width and height of the aforementioned irregularities formed on the lower surface 13b of the cover plate 51 and / or the case body 11, that is, it is integrally formed on the lower surface 13b of the cover plate 51 and / or the case body 11.

[0045] By providing the throttling structure 57, the flow rate of the refrigerant circulating in the main flow 60 becomes greater than that of the branch flow 70. As mentioned above, the terminal region A1 of each battery module 30 corresponds to the terminal portion 33 of each battery cell 31, so the terminal portion 33 can be efficiently cooled by the main flow 60 with its high flow rate. In other words, the terminal region A1 is the area of ​​each battery module that generates the most heat, so the area of ​​each battery module 30 that generates the most heat can be efficiently cooled by the main flow 60 with its high flow rate.

[0046] Furthermore, the throttling structure 57 may be provided at the branching section 61 of the main flow 60. The throttling structure 57 provided at the branching section 61 can be used to adjust the flow rate so as to create a flow rate difference between the refrigerant flowing through the outer main flow 62 and the inner main flow 63, or to adjust the flow rate so that the flow rates are equal.

[0047] Returning to Figure 5, the refrigerant flow path 55 of the water jacket 50 is provided with fins 58 that extend along the direction of refrigerant flow. The fins 58 are erected from the lower surface 13b of the case body 11 or the cover plate 51 and are integrally formed with the lower surface 13b of the case body 11 or the cover plate 51. Note that the fins 58 are not shown in Figure 6.

[0048] The fins 58 are preferably provided in the refrigerant flow path 55 in areas where refrigerant tends to accumulate and stagnate. Specifically, the fins 58 are provided in the corner regions 66 of the refrigerant flow path 55 and in the confluence sections where branched flow paths merge (for example, the confluence section 64 of the branched outer main flow 62 and inner main flow 63). The corner region 66 is an area that includes, for example, a section where the flow path bends at approximately a right angle or a section where the flow path bends at an acute angle, where refrigerant may accumulate and stagnate. Note that the corner region 66 may also include sections where the flow path bends at an obtuse angle, as long as stagnation occurs in that section.

[0049] In one example shown in Figure 5, the fins 58 are provided in the corner regions 66 on the rear ends of both the left and right sides of the main stream 60 (outer main stream 62, inner main stream 63), the corner region 66 on the front end of the left side of the main stream 60 (outer main stream 62, inner main stream 63), and the confluence section 64.

[0050] Figure 8 is an enlarged top view of the corner region 66 at the rear end of the main stream 60. The detailed structure of the fins 58 provided in the corner region 66 at the rear end of the main stream 60 will be described below with reference to Figure 8. However, the fins 58 provided in the front-end corner region 66 on the left side of the main stream 60, and the fins 58 provided in the confluence 64, have similar structures and will therefore not be described.

[0051] If fins 58 were not provided, stagnation could occur in the corner end 66c, which is the portion of the corner region 66 where the flow path bends at approximately a right angle. In this embodiment, fins 58 extending along the direction of refrigerant flow are provided in the corner regions 66 of the outer main flow 62 and the inner main flow 63. Furthermore, the fins 58 are provided continuously across two adjacent corner regions 66 and extend in a roughly U-shape when viewed from above.

[0052] Since fins 58 are provided in the corner region 66, stagnation in the refrigerant flow at the corner end 66c can be suppressed. In other words, the fins 58 function as rectifiers, allowing the refrigerant to flow smoothly, and as a result, the temperature control efficiency of the battery module 30 can be improved.

[0053] Multiple fins 58 are provided in parallel in each corner region 66. In this case, two fins 58 are provided in parallel in each corner region 66. This further suppresses the occurrence of stagnation at the corner end 66c.

[0054] The fins 58 are installed in the main stream 60, one of the two tributaries 70. As mentioned above, the main stream 60 has a high flow rate and high flow velocity, so stagnation is likely to occur at the corner end 66c. Therefore, by installing the fins 58 in the corner region 66 of the main stream 60, it is easy to obtain the effect of suppressing the occurrence of stagnation.

[0055] The fins 58 are not limited to the positions shown in Figure 5, but may be provided in any corner area and / or junction in the refrigerant flow path 55. Furthermore, the fins 58 may be provided in the corner area of ​​the branch flow 70. Specifically, the fins 58 may be provided in other corner areas or junctions (e.g., junction 73) in the refrigerant flow path 55.

[0056] When the fins 58 are provided at the confluence section 64 or 73, it is preferable that the downstream end of the fins 58 extends in the direction of the combined refrigerant flow. This allows the combined refrigerant to flow smoothly and suppresses the occurrence of stagnation at the confluence section.

[0057] The fins 58 may be provided in locations other than corner regions and / or confluence areas, for example, along a straight-line flow path.

[0058] (modified version) Figure 9 is a top view of a modified water jacket 50. The modified water jacket 50 does not have a branch 61 in the main flow 60. That is, the main flow 60 is composed of a single flow path provided along the terminal area A1 of each battery module 30, and the refrigerant flows without branching from the branch 56 to the outlet 54. The branch 70 has a left branch 71 and a right branch 72, similar to the embodiment described above, and merges with the main flow 60 at a confluence 73 at the downstream end of the right branch 72. The branch 70 is provided along the central area A2 of each battery module 30, and the refrigerant flows through it.

[0059] In the modified water jacket 50, the refrigerant flows through the main stream 60 in the order of the right battery module group 30R followed by the left battery module group 30L, while the refrigerant flows through the tributary stream 70 in the order of the left battery module group 30L followed by the right battery module group 30R. In other words, the refrigerant flowing through the main stream 60 and the refrigerant flowing through the tributary stream 70 form a counterflow.

[0060] Furthermore, although not shown in the diagram, it is preferable that the refrigerant flow path 55 of the modified water jacket 50 also has fins 58 extending along the direction of refrigerant flow. The configuration of the fins 58 is the same as described above, and therefore no further explanation is provided.

[0061] Even with this modified version of the water jacket 50, the same effect as the water jacket 50 described above can be achieved.

[0062] [Second Embodiment] Next, the battery pack 2 of the second embodiment will be described. In the following description, components common to the battery pack 1 of the first embodiment will be referred to by the same reference numerals, and the description of the first embodiment may be used by reference.

[0063] Figure 10 is a perspective view of the battery pack 2 of the second embodiment, showing the case cover 12 removed from the case body 11. Figure 11 is an exploded perspective view of the battery pack 2.

[0064] Battery pack 2, like battery pack 1 in the first embodiment, is installed in electric vehicles such as battery-powered electric vehicles, plug-in hybrid vehicles, and fuel cell vehicles, and stores electricity to supply to motors and other power sources that drive the electric vehicles. Battery pack 2 is installed under the floor of the electric vehicle. Battery pack 2 comprises a battery case 10, a plurality of battery modules 30, an electrical connection box 40, a water jacket 50, and an under cover 19.

[0065] The battery pack 2 is provided above the battery module 30 housed in the case body 11 and further comprises an upper case body 20 that houses the battery module 30, and an upper water jacket 80 provided at the bottom 23 of the upper case body 20 through which a coolant that regulates the temperature of the battery module 30 flows. The battery pack 2 is configured with the battery modules 30 stacked in two layers in the vertical direction. In the description of the second embodiment, the battery module 30 housed in the case body 11 may also be referred to as the lower battery module 30, and the battery module 30 housed in the upper case body 20 may also be referred to as the upper battery module 30.

[0066] Battery pack 2 has a larger number of battery modules 30 than battery pack 1 in the first embodiment, and is configured as a battery pack with a larger capacity than battery pack 1. As a result, an electric vehicle equipped with battery pack 2 can achieve a longer driving range than an electric vehicle equipped with battery pack 1.

[0067] The battery case 10 of the battery pack 2 has a case body 11, an upper case body 20, and a case cover 12. The configuration of the case body 11 in the second embodiment is basically the same as in the first embodiment, but it differs from the first embodiment in that seven battery modules 30 are arranged in the front-to-back direction in each of the left and right rows, and a total of 14 battery modules 30 are housed in the case body 11. The battery cells 31 of each battery module 30 are stacked in the front-to-back direction.

[0068] The upper case body 20 is located at the rear end of the case body 11. Specifically, a portion of the upper case body 20 is positioned to overlap the lower battery module 30, which is located in the last row when viewed from above, and is positioned in contact with or slightly separated from the upper surface of the battery module 30. The upper case body 20 houses two battery modules 30 that are arranged side by side in the left-right direction.

[0069] The case cover 12 covers the case body 11 to which the upper case body 20 is attached from above via a sealing material 18. Specifically, the case cover 12 covers both the case body 11 and the upper case body 20 from above, facing the upper surface of the battery module 30 housed in the case body 11 and the upper surface of the battery module 30 housed in the upper case body 20. The portion of the case cover 12 that covers the battery module 30 housed in the upper case body 20 protrudes upward. By covering the case body 11 from above via the sealing material 18, the inside of the battery case 10 is sealed. In this way, since the case body 11 and the upper case body 20 are covered from above by a common case cover 12, the height dimension of the battery pack can be reduced and the weight can be reduced compared to the case body 11 and the upper case body 20 each having separate case covers.

[0070] The battery pack 2 has three electrical connection boxes 40: one is located near the front end of the battery pack 1, and the other two are located in the center in the front-to-back direction. The three electrical connection boxes 40 are housed in the case body 11 and are located in front of the upper case body 20.

[0071] Figure 12 is a perspective view of the upper case body 20, the water jacket 50, and the upper water jacket 80. In Figure 12, the branch flow 70 of the water jacket 50 is not shown. Figure 13 shows the refrigerant flow path in the water jacket 50 and the upper water jacket 80.

[0072] The water jacket 50 provided at the bottom 13 of the lower case body 11 has the same configuration as in the first embodiment. That is, refrigerant flows through the main flow 60 in the order of the right battery module group 30R and the left battery module group 30L, and refrigerant flows through the branch flow 70 in the order of the left battery module group 30L and the right battery module group 30R. In other words, the refrigerant flowing through the main flow 60 and the refrigerant flowing through the branch flow 70 form a counterflow. Furthermore, the water jacket 50 of the second embodiment may also have the same configuration as a modified example of the first embodiment.

[0073] Furthermore, although not shown in the illustration, it is preferable that the refrigerant flow path 55 of the water jacket 50 in the second embodiment also be provided with fins 58 that extend along the direction of refrigerant flow.

[0074] The upper case body 20 has a bottom portion 23 and upright walls 24 erected around the bottom portion 23, and is configured in a tray shape. The upper case body 20 is provided with a plate member 21 that seals and covers the upper surface 23a of the bottom portion 23 from above. Two battery modules 30 are placed on the plate member 21 side by side in the left-right direction. Each battery module 30 is placed on the plate member 21 such that the battery cells 31 are stacked in the front-back direction.

[0075] The upper case body 20 has a plurality of case fixing parts 25. Each case fixing part 25 extends outward from the upper case body 20. Each case fixing part 25 is provided with a bolt insertion hole that penetrates vertically, and fastening members B (see Figure 14) such as bolts are inserted through the bolt insertion holes and fastened to the case body 11, thereby fixing the upper case body 20 to the case body 11. The fixing parts on the case body 11 side are provided in highly rigid locations such as the side wall 14 and the cross member 15.

[0076] The upper water jacket 80 is provided in the space partitioned between the upper surface 23a of the bottom 23 of the upper case body 20 and the plate member 21. Specifically, the upper case body 20 has grooves forming a refrigerant flow path 83 on its upper surface 23a, and the upper water jacket 80 is partitioned by the plate member 21 covering these grooves. The plate member 21 is joined to the upper case body 20, for example, by welding. The grooves forming the refrigerant flow path 83 may be formed in the plate member 21.

[0077] The upper water jacket 80 is provided on the upper surface 23a side of the bottom 23 of the upper case body 20, and has a different configuration from the water jacket 50 provided on the lower surface 13b side of the bottom 13 of the case body 11. With these water jackets 50 and upper water jacket 80, even if the cover plate 51 or plate member 21 is damaged due to a collision with an electric vehicle or the like and refrigerant leaks out from the water jacket 50 and / or upper water jacket 80, waterproofing of the lower battery module 30 housed in the case body 11 can be ensured.

[0078] The upper water jacket 80 is connected to the water jacket 50. The refrigerant flowing through the water jacket 50 branches off and flows into the upper water jacket 80, and the refrigerant that has flowed through the upper water jacket 80 rejoins the water jacket 50. The inlet 81 of the upper water jacket 80 is located on the front right side of the upper water jacket 80, and the outlet 82 is located on the front left side of the upper water jacket 80.

[0079] The inlet-side communication channel 85a, which connects the water jacket 50 to the inlet 81 of the upper water jacket 80, and the outlet-side communication channel 85b, which connects the water jacket 50 to the outlet 82 of the upper water jacket 80, are composed of pipe members 86 that extend in the vertical direction (see Figure 15). The inlet-side communication channel 85a and the outlet-side communication channel 85b are provided inward from the left and right side walls 14 of the case body 11 in the left-right direction.

[0080] The inlet communication channel 85a is connected to the upstream side of the main flow 60 of the water jacket 50, and the refrigerant flowing through the main flow 60 branches off and flows into the upper water jacket 80. The outlet communication channel 85b is connected to the downstream side of the main flow 60 of the water jacket 50, and the refrigerant that has flowed through the upper water jacket 80 rejoins the water jacket 50. In the illustrated example, the inlet communication channel 85a and the outlet communication channel 85b are connected to the inner main flow 63 of the water jacket 50, but they may also be connected to the outer main flow 62. In the following explanation, when the inlet communication channel 85a and the outlet communication channel 85b are not distinguished, they may be collectively referred to as the communication channel 85.

[0081] The communication channel 85 is positioned so as to overlap the cross member 15 when viewed from above. Because the communication channel 85 is located on the highly rigid cross member 15, damage to the communication channel 85 can be suppressed, for example, even if the battery pack 2 is subjected to an external impact.

[0082] The refrigerant flow path 83 of the upper water jacket 80 extends in the left-right direction, repeatedly folding back and forth, and is formed in a meandering manner from the inlet 81 to the outlet 82. Specifically, the refrigerant flowing in from the inlet 81 flows from the right side to the left side of the upper water jacket 80, then folds back and flows from the left side to the right side, and then flows again from the right side to the left side before flowing out to the water jacket 50 from the outlet 82. This configuration makes it possible to reduce temperature variations between the two battery modules 30 housed in the upper case body 20.

[0083] Furthermore, the upper water jacket 80 may also be provided with fins 58 that extend along the direction of refrigerant flow as described above.

[0084] Figure 14 is an enlarged perspective view of the area enclosed by the dashed line in Figure 13. The area enclosed by the dashed line includes the case fixing part 25 located on the left rear side of the upper case body 20.

[0085] The upright walls 24 of the upper case body 20 are erected around the upper water jacket 80, specifically around the plate member 21, and constitute the side walls of the tray-shaped upper case body 20. If the plate member 21 is damaged due to a collision with an electric vehicle or the like, refrigerant may leak from the upper water jacket 80. The upright walls 24 are configured to catch the leaked refrigerant. This configuration prevents refrigerant from coming into contact with the lower battery module 30.

[0086] Furthermore, the upper case body 20 is provided with a discharge section 26 that discharges refrigerant leaking from the upper water jacket 80 to a specific location on the case body 11. The thick solid arrows in Figure 14 show how refrigerant leaking from the upper water jacket 80 is discharged from the discharge section 26. Since the upper case body 20 is provided with a discharge section 26, the accumulation of refrigerant in the upper case body 20 is suppressed, and it is possible to prevent the accumulated refrigerant from splashing onto the lower battery module 30.

[0087] The specific location on the case body 11 is, for example, a different location from the lower battery module 30 housed in the case body 11. This ensures that the refrigerant discharged from the discharge section 26 does not come into contact with the lower battery module 30. However, the specific location on the case body 11 does not necessarily have to be a different location from the lower battery module 30. For example, if a part of the lower battery module 30 is covered by a waterproofing member such as a plate, the discharge section 26 may discharge the refrigerant to the location of that lower battery module 30.

[0088] The discharge section 26 includes a discharge passage 27 extending from a notch 24a provided in the vertical wall 24, and a discharge port 28 provided in the discharge passage 27, which opens in a position that does not overlap with the lower battery module 30 when viewed from above.

[0089] Since a notch 24a is provided in the vertical wall 24, refrigerant leaking from the upper water jacket 80 can be guided to the discharge passage 27. The notch 24a is formed from the upper end to the lower end of the vertical wall 24, allowing the leaked refrigerant to be smoothly guided to the discharge passage 27.

[0090] The discharge port 28 opens into the space between the lower battery module 30 located in the last row and the side wall portion 14 of the case body 11, and discharges the refrigerant that has leaked into this space. With this configuration, the discharge section 26 guides the refrigerant leaking from the upper water jacket 80 through the discharge passage 27 to the discharge port 28, and ensures that it is discharged from the discharge port 28 to a position where it does not come into contact with the lower battery module 30.

[0091] The discharge section 26 is provided integrally with the case fixing section 25. Specifically, the discharge passage 27 is formed in the portion of the case fixing section 25 that extends to the outer circumference of the upper case body 20, and the discharge port 28 is formed in the case fixing section 25 near the bolt insertion hole. Since the discharge section 26 is provided integrally with the case fixing section 25, the discharge section 26 is located in a highly rigid area, preventing damage to the discharge section 26 from external impacts. Furthermore, compared to a case where the discharge section 26 is provided separately from the case fixing section 25, the upper case body 20 can be made smaller.

[0092] Preferably, the discharge section 26 is provided on some of the case fixing sections 25, but not on the others. In the illustrated example, the discharge section 26 is provided only on the case fixing sections 25 located on the left rear and right rear sides of the multiple case fixing sections 25. In the case fixing sections 25 without a discharge section 26, the notch 24a is not formed and the vertical wall 24 extends, thus ensuring the rigidity of the upper case body 20. In this way, by providing a discharge section 26 on some of the case fixing sections 25 and not providing one on the others, it is possible to achieve both the discharge of leaked refrigerant and the assurance of the rigidity of the upper case body 20.

[0093] Figure 15 is a cross-sectional view of the communication channel 85 connecting the water jacket 50 and the upper water jacket 80. The thick arrows in Figure 15 indicate the flow of refrigerant. Here, the inlet communication channel 85a is shown as the communication channel 85, but the outlet communication channel 85b has the same configuration except for the direction of refrigerant flow.

[0094] The communication channel 85 is composed of a pipe member 86 that extends in the vertical direction. The pipe member 86 is connected to a lower connection part 88 provided in the water jacket 50 and an upper connection part 89 provided in the upper water jacket 80.

[0095] The lower connection portion 88 has an insertion hole 88a through which the pipe member 86 is inserted. Specifically, the insertion hole 88a is formed in the bottom portion 13 of the case body 11 and the cross member 15, and is a cylindrical hole that supports the lower end of the inserted pipe member 86. An O-ring 90 is provided on the outer circumference of the lower end of the pipe member 86, and the lower end of the pipe member 86 is liquid-tightly connected to the lower connection portion 88 via the O-ring 90.

[0096] The upper connection portion 89 has a through hole 89a through which the pipe member 86 is inserted. Specifically, the through hole 89a is formed in the upper case body 20 at the position of the inlet 81 of the upper water jacket 80 and is a cylindrical hole that supports the upper end of the inserted pipe member 86. An O-ring 90 is provided on the outer circumference of the upper end of the pipe member 86, and the upper end of the pipe member 86 is liquid-tightly connected to the upper connection portion 89 via the O-ring 90.

[0097] A rubber mount 91, which is an example of an elastic member molded from rubber or the like, is provided on the outer circumference of the upper end of the pipe member 86. The rubber mount 91 rests on an annular flange portion 86a formed on the outer circumference of the upper end of the pipe member 86. When the pipe member 86 is connected to the water jacket 50 and the upper water jacket 80, the rubber mount 91 is pressed vertically against the lower end of the upper connection portion 89 and comes into contact with it.

[0098] The vertical reaction force of the rubber mount 91 restricts the vertical movement of the pipe member 86, for example, during the flow of refrigerant. Furthermore, even if a torque is applied to the pipe member 86 that rotates it, for example, the vertical reaction force of the rubber mount 91 suppresses the occurrence of axial misalignment of the pipe member 86.

[0099] Figure 16(a) is a perspective view of the upper end of the pipe member 86 on which the rubber mount 91 is provided, and Figure 16(b) is a cross-sectional view thereof.

[0100] The rubber mount 91 has a notch 92 provided on the part that is pressed against the upper connection portion 89 of the upper water jacket 80 (i.e., the upper surface of the rubber mount 91). Because the notch 92 is provided, during inspection after assembly of the battery pack 2, the damage to the O-ring 90 can be inspected by injecting compressed air (thick arrow in Figure 16(b)) into the pipe member 86 while it is connected to the upper water jacket 80. Specifically, as shown in Figure 16(b), if the O-ring 90 is damaged, the compressed air injected into the pipe member 86 will flow out of the flow path through the damaged part of the O-ring 90 and the notch 92 of the rubber mount 91.

[0101] Therefore, if compressed air is injected into the pipe member 86 and compressed air is detected near the rubber mount 91, it can be presumed that the O-ring 90 is damaged. The configuration with the notch 92 makes it possible to provide a battery pack 2 that sufficiently ensures the liquid tightness of the communication passage 85.

[0102] Although embodiments and modifications of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to these embodiments. It is clear to those skilled in the art that various variations or modifications can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of the present invention. Furthermore, the components of the above embodiments may be combined arbitrarily without departing from the spirit of the invention.

[0103] For example, in the embodiments described above, the multiple battery cells 31 housed in the battery case 10 were stacked to form a modularized battery module 30, but they may also be stacked without being modularized (i.e., a cell stack). Furthermore, the battery cells 31 housed in the battery case 10 are not limited to the pouch-type cells or prismatic cells described above, but may also be cylindrical cells.

[0104] Furthermore, although the embodiments described above show a configuration in which the flow path branches into two at branching sections 56 and 61, a configuration in which the flow path branches into three or more at branching sections 56 and 61 is also possible.

[0105] This specification includes at least the following: The components and other elements corresponding to those in the embodiments described above are shown in parentheses as examples, but are not limited thereto.

[0106] (1) Multiple cell stacks (battery module 30) in which multiple battery cells (battery cells 31) are stacked, A battery case (battery case 10) housing the aforementioned cell stack, A battery pack (battery packs 1, 2) comprising a water jacket (water jacket 50) provided below the cell stack, through which a refrigerant for regulating the temperature of the cell stack flows, The plurality of cell stacks include a first cell stack group (right-side battery module group 30R) provided on one side in a predetermined direction, and a second cell stack group (left-side battery module group 30L) provided on the other side. The water jacket has a branching section (branching section 56) that branches from the inlet (inlet 53) into at least a first channel (main channel 60) and a second channel (tributary channel 70), The refrigerant flows through the first flow path in the order of the first cell stack group and the second cell stack group. The refrigerant flows through the second flow path in the order of the second cell stack group and the first cell stack group. Battery pack.

[0107] According to (1), the refrigerant flows through the first channel branching from the inlet in the order of the first cell stack group followed by the second cell stack group, and through the second channel in the order of the second cell stack group followed by the first cell stack group. As a result, the refrigerant flowing through the first channel and the refrigerant flowing through the second channel form a counterflow, which reduces temperature variations between the first cell stack group and the second cell stack group. Therefore, the temperature control performance of the cell stack can be improved.

[0108] (2) The battery pack described in (1), The first channel is provided along the first region (terminal region A1) of each cell stack, The second channel is provided along a second region (central region A2) that is different from the first region of each cell stack. Battery pack.

[0109] According to (2), since the first and second regions of each cell stack are temperature-controlled by separate channels (first channel, second channel), the temperature of each cell stack can be effectively controlled.

[0110] (3) The battery pack described in (2), The first region of each cell stack is the terminal portion (terminal portion 33) of the battery cell, The second region of each cell stack is the central part of the battery cell. Battery pack.

[0111] According to (3), the terminal portion of the battery cell and the central portion of the battery cell are cooled by separate channels, so that each cell stack can be cooled effectively.

[0112] (4) The battery pack described in (2), The aforementioned region of each cell stack is a region of each cell stack that generates a large amount of heat. The second region of each cell stack is a region that generates less heat than the first region. Battery pack.

[0113] According to (4), since the regions of each cell stack that generate a lot of heat and the regions that generate little heat are cooled by separate channels, each cell stack can be cooled effectively.

[0114] (5) A battery pack as described in (3) or (4), The branch section is provided with a throttling structure (throttling structure 57) that reduces the flow rate of the refrigerant flowing into the second flow path. Battery pack.

[0115] According to (5), a throttling structure is provided at the branching point to reduce the flow rate of the refrigerant flowing into the second channel, so that a flow rate difference can be created between the first channel and the second channel. The areas where the battery cell terminals are located and the areas of each cell stack that generate a lot of heat are cooled by the first channel, which has a higher flow rate than the second channel, so that the cooling performance of the cell stack by the water jacket can be further improved.

[0116] (6) A battery pack as described in any of (1) to (5), The water jacket further has other branching sections (branching section 61) provided in the first flow path, The first channel includes a third channel (outer main channel 62) and a fourth channel (inner main channel 63) that branch off from the other branching section. Battery pack.

[0117] According to (6), even if an object collides with the bottom surface of the battery pack and the third (or fourth) channel of the water jacket becomes blocked, the flow of refrigerant in the first channel can be maintained through the fourth (or third) channel.

[0118] (7) The battery pack described in (6), The second flow path has a merging section (merging section 73) where the refrigerant flows through the second cell stack group and the first cell stack group in that order, and then merges with the third flow path or the fourth flow path. Battery pack.

[0119] According to (7), the second channel merges with the third or fourth channel included in the first channel, thus simplifying the channel structure.

[0120] (8) A battery pack as described in any of (1) to (7), At least one of the first flow path and the second flow path is provided with a fin (fin 58) that extends along the flow of the refrigerant. Battery pack.

[0121] According to (8), the presence of fins straightens the flow of the refrigerant and suppresses the formation of stagnation. As a result, the temperature control efficiency of the multiple cell stacks can be improved.

[0122] (9) The battery pack described in (8), The fins are provided in the corner region (corner region 66) and / or the confluence section (confluence section 64, 73) where branched channels merge in at least one of the first channel and the second channel. Battery pack.

[0123] According to (9), the presence of fins straightens the flow of refrigerant in the corner region and / or confluence, suppressing the occurrence of stagnation. As a result, the temperature control efficiency of the multiple cell stacks can be improved.

[0124] (10) The battery pack described in (9), The flow velocity of the refrigerant flowing through the first channel is greater than the flow velocity of the refrigerant flowing through the second channel. The fins are provided in the corner region and / or the confluence portion of the first flow path. Battery pack.

[0125] According to (10), although the first channel has a high flow velocity and is prone to stagnation, the formation of stagnation can be suppressed by providing fins. [Explanation of symbols]

[0126] 1 Battery Pack 2 Battery Packs 10 Battery Cases 30 Battery Modules (Cell Stacks) 30L left-side battery module group (2nd cell stack group) 30R Right-side battery module group (1st cell stack group) 31 battery cells 33 Terminal section 50 Water Jacket 53 Inlet 56 Branching point 58 fins 60 Main stream (first channel) 61 Branching point (other branching points) 62 Outer main channel (third channel) 63 Inner main channel (4th channel) 64 Confluence 66 Corner area 70 Tributary (Second channel) 73 Confluence A1 terminal area (first area) A2 central area (second area)

Claims

1. Multiple cell stacks, in which multiple battery cells are stacked, A battery case housing the aforementioned cell stack, A battery pack comprising a water jacket provided below the cell stack, through which a refrigerant for regulating the temperature of the cell stack flows, The plurality of cell stacks include a first cell stack group provided on one side in a predetermined direction and a second cell stack group provided on the other side. The water jacket has a branching section that branches from the inlet into at least a first channel and a second channel, The refrigerant flows through the first flow path in the order of the first cell stack group and the second cell stack group. The refrigerant flows through the second flow path in the order of the second cell stack group and the first cell stack group. Battery pack.

2. A battery pack according to claim 1, The first channel is provided along the first region of each cell stack, The second channel is provided along a second region that is different from the first region of each cell stack. Battery pack.

3. A battery pack according to claim 2, The first region of each cell stack is the terminal portion of the battery cell, The second region of each cell stack is the central part of the battery cell. Battery pack.

4. A battery pack according to claim 2, The first region of each cell stack is a region of each cell stack that generates a large amount of heat. The second region of each cell stack is a region that generates less heat than the first region. Battery pack.

5. A battery pack according to claim 3 or 4, The branching section is provided with a throttling structure that reduces the flow rate of the refrigerant flowing into the second flow path. Battery pack.

6. A battery pack according to any one of claims 1 to 4, The water jacket further has other branching portions provided in the first flow path, The first channel includes a third channel and a fourth channel that branch off from the other branching section. Battery pack.

7. A battery pack according to claim 6, The second flow path has a merging section where the refrigerant flows through the second cell stack group and the first cell stack group in that order, and then merges with the third flow path or the fourth flow path. Battery pack.

8. A battery pack according to any one of claims 1 to 4, At least one of the first flow path and the second flow path is provided with fins that extend along the flow of the refrigerant. Battery pack.

9. A battery pack according to claim 8, The fin is provided in the corner region and / or the confluence where branched channels meet in at least one of the first channel and the second channel. Battery pack.

10. A battery pack according to claim 9, The flow velocity of the refrigerant flowing through the first channel is greater than the flow velocity of the refrigerant flowing through the second channel. The fin is provided in the corner region and / or the confluence portion of the first flow path. Battery pack.

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