Battery pack

Abstract

To provide a battery pack which can freely control cooling efficiency of each battery cell, in cooling design to more uniformly cool a plurality of battery cells.SOLUTION: A battery pack includes a plurality of battery cells (11) to be laminated, and a plate member (31) which is thermally connected to the plurality of battery cells (11). The plate member (31) includes an inner wall (47) for defining and forming a refrigerant passage (40). The refrigerant passage (40) is configured to flow a refrigerant from a refrigerant inlet to a refrigerant outlet in the plate member (31) while meandering. In the inner wall (47), an uneven part (46) whose shape changes in a flow direction of the refrigerant in the refrigerant passage (40) is provided. The opening constituted by the refrigerant passage (40) includes a first opening region (91) where the uneven part (46) is arranged, and a second opening region (92) positioned on a side opposite to the plurality of battery cells (11) while sandwiching the first opening region (91).SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a battery pack. [Background technology]

[0002] For example, International Publication No. 2019 / 150705 (Patent Document 1) discloses a power supply device including a battery unit consisting of multiple battery cells and a cooling plate that is thermally coupled to the battery cells and dissipates the thermal energy of the battery cells. A refrigerant passage is provided inside the cooling plate to circulate a refrigerant.

[0003] Furthermore, JP 2017-534143 A (Patent Document 2) discloses a flat cooling plate for a secondary battery. The cooling plate for a secondary battery has a plurality of cooling sections arranged along its longitudinal direction and spaced apart from one another. The inner surfaces of the cooling sections are provided with a plurality of reinforcing ribs.

[0004] In addition, Chinese Utility Model Publication No. 213816250 (Patent Document 3) discloses a battery core heat dissipation module equipped with a water-cooled plate, which has at least one passageway formed therein and a plurality of heat dissipation teeth installed in the passageway. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2019 / 150705 [Patent Document 2] Special Publication No. 2017-534143 [Patent Document 3] China Utility Model Publication No. 213816250 Summary of the Invention [Problem to be solved by the invention]

[0006] As disclosed in the above-mentioned Patent Documents 1 to 3, there are known battery packs equipped with a cooling mechanism in which a cooling plate is connected to a cell stack consisting of multiple stacked battery cells and a refrigerant passage is provided within the cooling plate. However, it is difficult to uniformly cool multiple battery cells due to various factors such as the stacking position of the battery cells in the cell stack, the position of the battery cells in the direction of the refrigerant flow, and the temperature environment around the battery cells. Therefore, a method for freely controlling the cooling efficiency of each battery cell is required.

[0007] Therefore, an object of the present invention is to solve the above-mentioned problems and to provide a battery pack that can freely control the cooling efficiency of each battery cell in a cooling design that aims to cool multiple battery cells more evenly. [Means for solving the problem]

[0008] [1] A battery pack comprising: a plurality of stacked battery cells; and a plate member thermally connected to the plurality of battery cells, the plate member including an inner wall that defines a refrigerant passage through which a refrigerant flows; the refrigerant passage is configured so that the refrigerant flows in a serpentine manner from a refrigerant inlet to a refrigerant outlet in the plate member; the plurality of battery cells and the inner wall are provided with uneven portions that are concave and / or convex with respect to an opening formed by the refrigerant passage and whose shape changes in the direction of refrigerant flow in the refrigerant passage; the opening formed by the refrigerant passage includes a first opening area in which the uneven portions are arranged, and the second opening area located on the opposite side of the first opening area from the plurality of battery cells.

[0009] [1] A battery pack comprising a plurality of stacked battery cells and a plate member thermally connected to the plurality of battery cells, the plate member including an inner wall that defines a refrigerant passage through which a refrigerant flows, the inner wall having a concave and / or convex portion that is concave and / or convex relative to an opening of the refrigerant passage and whose shape changes in the direction of refrigerant flow in the refrigerant passage.

[0010] In a battery pack configured in this manner, the inner walls that define the refrigerant passages are provided with unevenness, and the shape of the unevenness is changed in the direction of refrigerant flow to change the contact area between the refrigerant flowing through the refrigerant passages and the inner walls. This allows for flexible control of the cooling efficiency of each battery cell in a cooling design that aims to more evenly cool multiple battery cells.

[0011] [2] The battery pack described in [1], wherein the refrigerant passage includes a first passage region and a second passage region located downstream of the first passage region in the refrigerant flow, and the uneven portion is arranged so that the surface area of the inner wall in the second passage region is larger than the surface area of the inner wall in the first passage region per unit distance in the refrigerant flow direction in the refrigerant passage.

[0012] In a battery pack configured in this manner, the second passage region is located downstream of the first passage region in the refrigerant flow direction, so a relatively high-temperature refrigerant flows through the second passage region, and a relatively low-temperature refrigerant flows through the first passage region. In this case, by providing the concave-convex portion so that the surface area of the inner wall in the second passage region is larger than the surface area of the inner wall in the first passage region, the cooling efficiency of the battery cells facing the second passage region can be improved.

[0013] [3] The battery pack according to [1] or [2], further comprising a cell stack constituted by a plurality of the battery cells stacked in a predetermined direction, wherein the refrigerant passage includes a third passage region facing an end of the cell stack in the predetermined direction and a fourth passage region facing an intermediate portion of the cell stack in the predetermined direction, and the uneven portion is arranged so that the surface area of the inner wall in the fourth passage region is larger than the surface area of the inner wall in the third passage region per unit distance in the flow direction of the refrigerant in the refrigerant passage.

[0014] In a battery pack configured in this manner, the battery cells located in the middle of the cell stack have a harder time dissipating heat than the battery cells located at the ends of the cell stack, and therefore become hotter. In this case, by providing the concave-convex portion so that the surface area of the inner wall in the fourth passage region facing the middle of the cell stack is larger than the surface area of the inner wall in the third passage region facing the ends of the cell stack, the cooling efficiency of the middle of the cell stack can be improved.

[0015] [4] A battery pack according to any one of [1] to [3], comprising: a case body having a side portion; an electronic component unit housed in the case body; a first cell stack constituted by a plurality of stacked battery cells and housed in the case body at a position adjacent to the side portion; and a second cell stack constituted by a plurality of stacked battery cells and housed in the case body at a position adjacent to the electronic component unit, wherein the refrigerant passage includes a fifth passage region facing the first cell stack and a sixth passage region facing the second cell stack, and the uneven portion is arranged so that the surface area of the inner wall in the sixth passage region is larger than the surface area of the inner wall in the fifth passage region per unit distance in the flow direction of the refrigerant in the refrigerant passage.

[0016] In a battery pack configured in this manner, the second cell stack is positioned adjacent to the electronic component unit, which is a heat-generating body, and therefore has a relatively high temperature, while the first cell stack is positioned adjacent to the side of the case body and therefore has a relatively low temperature. In this case, by providing the concave-convex portion so that the surface area of the inner wall in the sixth passage region facing the second cell stack is larger than the surface area of the inner wall in the fifth passage region facing the first cell stack, the cooling efficiency of the second cell stack can be improved.

[0017] [5] A battery pack described in any one of [1] to [4], wherein the refrigerant passage includes a plurality of passage areas extending parallel to each other and connected in a line from the upstream side to the downstream side of the refrigerant flow, and the shape of the uneven portion does not change in the flow direction of the refrigerant in each of the passage areas in the refrigerant passage, and is different from one another among the plurality of passage areas.

[0018] In the battery pack configured in this manner, the plate member can be easily provided with refrigerant passages including a plurality of passage areas with varying concave and convex shapes by using extrusion molding.

[0019] [6] The battery pack according to any one of [1] to [5], wherein the uneven portion is provided along the direction of flow of the refrigerant in the refrigerant passage. [Effects of the Invention]

[0020] As described above, according to the present invention, it is possible to provide a battery pack that is capable of freely controlling the cooling efficiency of each battery cell in a cooling design that aims to cool multiple battery cells more evenly. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 2 is an exploded view of the battery pack according to the first embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view showing a battery cell that constitutes the battery pack in FIG. [Figure 3] FIG. 2 is a cross-sectional view showing the battery pack in FIG. [Figure 4] 2 is another cross-sectional view showing the battery pack in FIG. 1. [Figure 5] 5 is a cross-sectional view showing a modified example of the uneven portion provided on the plate member in FIG. [Figure 6] FIG. 10 is a cross-sectional view showing a battery pack in accordance with a second embodiment of the present invention. [Figure 7] 7 is a cross-sectional view showing the battery pack as seen in the direction of the arrows on line VII-VII in FIG. 6. [Figure 8]8 is a cross-sectional view showing the battery pack as seen in the direction of the arrows on line VIII-VIII in FIG. 6. [Figure 9] 9 is a cross-sectional view showing the battery pack as seen in the direction of the arrows on line IX-IX in FIG. 6. [Figure 10] FIG. 10 is a cross-sectional view showing a battery pack in accordance with a third embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the accompanying drawings, in which the same or corresponding elements are designated by the same reference numerals.

[0023] (Embodiment 1) Fig. 1 is an exploded view of a battery pack according to a first embodiment of the present invention. Fig. 2 is a perspective view showing battery cells constituting the battery pack in Fig. 1. Figs. 3 and 4 are cross-sectional views showing the battery pack in Fig. 1. The cross section of the battery pack shown in Fig. 3 corresponds to the cross section of the battery pack seen in the direction of the arrows on line III-III in Fig. 1, and the cross section of the battery pack shown in Fig. 4 corresponds to the cross section of the battery pack seen in the direction of the arrows on line IV-IV in Fig. 3.

[0024] 1 to 4, a battery pack 100 is used as a power source for driving a vehicle such as a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), or a battery electric vehicle (BEV).

[0025] In this specification, for the convenience of explaining the structure of the battery pack 100, the stacking direction of the multiple battery cells 11 (described later) and the axis extending horizontally are referred to as the "Y axis," the direction perpendicular to the Y axis and extending horizontally are referred to as the "X axis," and the axis extending vertically are referred to as the "Z axis."

[0026] First, the overall structure of the battery pack 100 will be described. The battery pack 100 has a plurality of battery cells 11. The plurality of battery cells 11 are stacked in the Y-axis direction. The battery cells 11 are lithium-ion batteries. The battery cells 11 are rectangular and have the shape of a thin rectangular parallelepiped plate. The plurality of battery cells 11 are stacked so that the Y-axis direction is the thickness direction of the battery cells 11.

[0027] The battery cell 11 has an exterior body 12. The exterior body 12 is made of a rectangular parallelepiped housing and forms the exterior of the battery cell 11. The exterior body 12 contains an electrode assembly and an electrolyte.

[0028] Exterior body 12 has a first side surface 13, a second side surface 14, a top surface 15, and a bottom surface 16. Each of first side surface 13 and second side surface 14 is a plane perpendicular to the Y axis. First side surface 13 and second side surface 14 face opposite each other in the Y axis direction. Each of first side surface 13 and second side surface 14 has the largest area among the multiple side surfaces that exterior body 12 has.

[0029] Top surface 15 and bottom surface 16 each consist of a plane perpendicular to the Z axis. Top surface 15 faces upward. Bottom surface 16 faces downward. Top surface 15 is provided with gas exhaust valve 17 for exhausting gas to the outside of exterior body 12 when the internal pressure of exterior body 12 exceeds a predetermined value due to gas generated inside exterior body 12.

[0030] The battery cell 11 further has electrode terminals 18, each of which is a pair of a positive terminal 18P and a negative terminal 18N. The electrode terminals 18 are provided on the top surface 15. The positive terminal 18P and the negative terminal 18N are provided spaced apart from each other in the X-axis direction. The positive terminal 18P and the negative terminal 18N are provided on either side of the gas release valve 17 in the X-axis direction.

[0031] The multiple battery cells 11 are stacked such that the first side surfaces 13 face each other and the second side surfaces 14 face each other between adjacent battery cells 11 in the Y-axis direction. As a result, the positive electrode terminals 18P and negative electrode terminals 18N are arranged alternately in the Y-axis direction in which the multiple battery cells 11 are stacked. Between adjacent battery cells 11 in the Y-axis direction, the positive electrode terminals 18P and negative electrode terminals 18N arranged in the Y-axis direction are connected to each other by a bus bar (not shown). The multiple battery cells 11 are electrically connected to each other in series.

[0032] A cell stack 10 (10A, 10B) is made up of multiple battery cells 11 stacked in the Y-axis direction. The cell stack 10 has a rectangular parallelepiped shape. As a typical example, the length of the cell stack 10 in the Y-axis direction is greater than the length of the cell stack 10 in the Z-axis direction, and greater than the length of the cell stack 10 in the X-axis direction. The cell stack 10A and the cell stack 10B are arranged side by side in the X-axis direction with a gap between them.

[0033] The battery pack 100 further includes a case body 21. The case body 21 is a box having an overall rectangular parallelepiped appearance. A plurality of battery cells 11 are housed inside the case body 21 (internal space 70).

[0034] The case body 21 has a plate member 31, a case side portion 23, a case top portion 24, and a case bottom portion 22. The plate member 31, together with the case side portion 23 and the case top portion 24, defines an internal space 70. The case bottom portion 22 is disposed at the bottom of the case body 21.

[0035] The plate member 31 is made of a plate material extending parallel to the X-axis-Y plane, with the thickness direction being in the Z-axis direction. The case side portion 23 rises upward from the upper surface of the plate member 31 and forms an opening at its tip. The case top portion 24 faces the plate member 31 in the Z-axis direction, with the internal space 70 sandwiched between them. The case top portion 24 closes the opening formed by the upper end of the case side portion 23.

[0036] The case body 21 is made of metal. The plate member 31 is made of a different type of metal from the case side portions 23 and the case bottom portion 22. The thermal conductivity of the metal that forms the plate member 31 is greater than the thermal conductivity of the metal that forms the case side portions 23 and the case bottom portion 22. As an example, the plate member 31 is made of aluminum, and the case side portions 23 and the case bottom portion 22 are made of (steel plate).

[0037] The plurality of battery cells 11 are placed on a plate member 31. The plate member 31 is thermally connected to the plurality of battery cells 11. The plate member 31 is connected to the plurality of battery cells 11 so as to enable heat transfer between the plurality of battery cells 11 and the plate member 31. A heat transfer member 25 is interposed between the bottom surface 16 of the battery cell 11 and the plate member 31. The heat transfer member 25 may be made of an adhesive material (adhesive) or a non-adhesive material.

[0038] The battery cells 11 are restrained at both ends in the Y-axis direction by the case side portions 23. The case side portions 23 apply a restraining force (compressive force) to the battery cells 11 in the Y-axis direction.

[0039] The case body 21 may be configured so that the internal space 70 is defined by the case side portions 23, the case top portion 24, and the case bottom portion 22. In this case, the plate member 31 may be connected to the case bottom portion 22 from outside the internal space 70.

[0040] Heat generated in the plurality of battery cells 11 is dissipated to the outside via the coolant flowing inside the plate member 31. The structure of the plate member 31 will be described in more detail below.

[0041] The plate member 31 has an inner wall 47. The inner wall 47 defines a refrigerant passage 40 through which a refrigerant flows. The refrigerant is a fluid that can transfer heat generated in the battery cells 11 to the outside, and may be a liquid or a gas. The refrigerant passage 40 extends within the plane in which the plate member 31 extends (the X-axis-Y-axis plane). The refrigerant passage 40 extends opposite the multiple battery cells 11 in the vertical direction.

[0042] The refrigerant passage 40 includes multiple passage regions 41 (41p, 41q, 41r, 41s). The passage region 41p, the passage region 41q, the passage region 41r, and the passage region 41s are arranged in the listed order from upstream to downstream of the refrigerant flow in the refrigerant passage 40. Each of the passage regions 41, namely, the passage region 41p, the passage region 41q, the passage region 41r, and the passage region 41s, extends in the Y-axis direction. The passage region 41p, the passage region 41q, the passage region 41r, and the passage region 41s meander along the X-axis direction while extending alternately in the +Y-axis direction and the −Y-axis direction.

[0043] The passage region 41p and the passage region 41q face the cell stack 10A in the vertical direction, and the passage region 41r and the passage region 41s face the cell stack 10B in the vertical direction.

[0044] The inner wall 47 is provided with an uneven portion 46. The uneven portion 46 has a concave and convex shape relative to the opening of the refrigerant passage 40. The uneven portion 46 is provided to increase the surface area of the inner wall 47. The uneven portion 46 is provided on the upper surface of the inner wall 47 that forms the refrigerant passage 40. The refrigerant passage 40 is located on the opposite side of the uneven portion 46 from the multiple battery cells 11 (internal space 70) in the Z axis direction. When the plate member 31 is cut along a plane (X-axis-Z axis plane) perpendicular to the refrigerant flow in the refrigerant passage 40, the uneven portion 46 has a comb-like shape. The uneven portion 46 is composed of multiple ribs that are spaced apart from each other in the X axis direction. Each rib forms a convex shape that protrudes in the -Z axis direction and extends in the Y axis direction, and between adjacent ribs in the X axis direction, a concave shape that is recessed in the +Z axis direction and extends in the Y axis direction is formed.

[0045] The shape of the uneven portion 46 changes in the direction of refrigerant flow in the refrigerant passage 40. This configuration changes the contact area between the refrigerant flowing through the refrigerant passage 40 and the inner wall 47 on which the uneven portion 46 is provided, making it possible to adjust the efficiency of heat transfer from the plate member 31 to the refrigerant. This makes it possible to freely control the cooling efficiency of each battery cell 11 in a cooling design that aims to cool multiple battery cells 11 more evenly.

[0046] More specifically, the shape of the uneven portion 46 changes at the boundary between the passage region 41p and a passage region 41q located downstream of the passage region 41p in the refrigerant flow of the refrigerant passage 40, changes at the boundary between the passage region 41q and a passage region 41r located downstream of the passage region 41q in the refrigerant flow of the refrigerant passage 40, and changes at the boundary between the passage region 41r and a passage region 41s located downstream of the passage region 41r in the refrigerant flow of the refrigerant passage 40. The shape of the uneven portion 46 does not change in each of the passage regions 41p, 41q, 41r, and 41s.

[0047] The uneven portion 46 is arranged so that the surface area of the inner wall 47 in the passage region 41 located downstream of the refrigerant flow in the refrigerant passage 40 is larger per unit distance in the refrigerant flow direction than the surface area of the inner wall 47 in the passage region 41 located upstream of the refrigerant flow in the refrigerant passage 40.

[0048] The number of ribs forming the uneven portion 46 in the passage region 41q is greater than the number of ribs forming the uneven portion 46 in the passage region 41p. As a result, the surface area of the inner wall 47 in the passage region 41q per unit distance in the refrigerant flow direction in the refrigerant passage 40 is greater than the surface area of the inner wall 47 in the passage region 41p. The number of ribs forming the uneven portion 46 in the passage region 41r is greater than the number of ribs forming the uneven portion 46 in the passage region 41q. As a result, the surface area of the inner wall 47 in the passage region 41r per unit distance in the refrigerant flow direction in the refrigerant passage 40 is greater than the surface area of the inner wall 47 in the passage region 41q. The number of ribs forming the uneven portion 46 in the passage region 41s is greater than the number of ribs forming the uneven portion 46 in the passage region 41r. As a result, the surface area of the inner wall 47 in the passage region 41s per unit distance in the refrigerant flow direction in the refrigerant passage 40 is larger than the surface area of the inner wall 47 in the passage region 41r.

[0049] The refrigerant receives heat from the multiple battery cells 11 as it flows through the refrigerant passage 40. For this reason, the refrigerant temperature increases as it moves from the upstream to the downstream side of the refrigerant flow in the refrigerant passage 40, which may result in the battery cells 11 not being cooled evenly. To address this issue, the unevenness 46 is provided so that the surface area of the inner wall 47 in the passage region 41 located downstream of the refrigerant flow is larger than the surface area of the inner wall 47 in the passage region 41 located upstream of the refrigerant flow. This promotes heat transfer from the plate member 31 to the refrigerant flowing through the refrigerant passage 40 in the passage region 41 located downstream of the refrigerant flow. This allows the multiple battery cells 11 to be cooled more evenly.

[0050] Furthermore, the shape of the uneven portion 46 does not change in the direction of refrigerant flow in the refrigerant passage 40 in each of the passage regions 41p, 41q, 41r, and 41s, and is different among the passage regions 41p, 41q, 41r, and 41s. This configuration allows the plate member 31 to be made of an extruded metal such as aluminum.

[0051] The battery pack 100 in this embodiment includes a plurality of stacked battery cells 11 and a plate member 31 thermally connected to the plurality of battery cells 11. The plate member 31 includes an inner wall 47 that defines a refrigerant passage 40 through which a refrigerant flows. The refrigerant passage 40 is configured so that the refrigerant flows in a serpentine manner from a refrigerant inlet to a refrigerant outlet in the plate member 31. The plurality of battery cells 11 and the inner wall 47 are provided with uneven portions 46 that are concave and / or convex with respect to the opening of the refrigerant passage 40 and whose shape changes in the direction of refrigerant flow in the refrigerant passage 40. The opening of the refrigerant passage 40 includes a first opening region 91 in which the uneven portions 46 are arranged, and a second opening region 92 located on the opposite side of the first opening region 91 from the plurality of battery cells 11.

[0052] Fig. 5 is a cross-sectional view showing a modified example of the concave-convex portion provided on the plate member in Fig. 4. Referring to Fig. 5, in this modified example, concave-convex portion 46 has an arc-shaped recessed shape relative to the opening of refrigerant passage 40. The curvature of the arc forming concave-convex portion 46 in passage region 41q is greater than the curvature of the arc forming concave-convex portion 46 in passage region 41p. As a result, the surface area of inner wall 47 in passage region 41q per unit distance in the refrigerant flow direction in refrigerant passage 40 is greater than the surface area of inner wall 47 in passage region 41p.

[0053] Even with this configuration, heat transfer from the plate member 31 to the refrigerant flowing through the refrigerant passage 40 can be further promoted in the passage region 41q located downstream in the refrigerant flow.

[0054] In this embodiment, the shape of the uneven portion 46 changes intermittently (at regular intervals along the direction of refrigerant flow in the refrigerant passage 40), but this is not limiting, and the shape of the uneven portion in the present invention may change continuously in the direction of refrigerant flow in the refrigerant passage. Also, in a cooling design aimed at more evenly cooling multiple battery cells, the opening area of the refrigerant passage may be further adjusted in addition to the surface area of the inner wall.

[0055] (Embodiment 2) Fig. 6 is a cross-sectional view showing a battery pack in accordance with embodiment 2 of the present invention. Fig. 6 corresponds to Fig. 3 in embodiment 1. Fig. 7 is a cross-sectional view showing the battery pack as seen in the direction of the arrows on line VII-VII in Fig. 6. Fig. 8 is a cross-sectional view showing the battery pack as seen in the direction of the arrows on line VIII-VIII in Fig. 6. Fig. 9 is a cross-sectional view showing the battery pack as seen in the direction of the arrows on line IX-IX in Fig. 6.

[0056] The battery pack of the present embodiment has a structure basically similar to that of battery pack 100 of Embodiment 1. Hereinafter, description of the overlapping structure will not be repeated.

[0057] 6 to 9, the battery pack in this embodiment has a plurality of battery cells 11 and plate members 31 (31A, 31B, 31C). The plurality of battery cells 11 stacked in the Y-axis direction constitute a cell stack 10. The plate members 31A, 31B, and 31C are aligned in the Y-axis direction, and adjacent plate members 31 in the Y-axis direction are connected to each other. Each of the plate members 31A, 31B, and 31C is made of an extruded metal such as aluminum.

[0058] A refrigerant passage 40 extending in the Y-axis direction is formed in the plate member 31 (31A, 31B, 31C). The refrigerant passage 40 includes a plurality of passage regions 42 (42p, 42q, 42r). The passage region 42p, the passage region 42q, and the passage region 42r correspond to sections of the refrigerant passage 40 formed in the plate member 31A, the plate member 31B, and the plate member 31C, respectively. The passage region 42p, the passage region 42q, and the passage region 42r are arranged in this order from the upstream side to the downstream side of the refrigerant flow in the refrigerant passage 40. The passage region 42p and the passage region 42r face both ends of the cell stack 10 in the Y-axis direction in the up-down direction. The passage region 42q faces the middle portion of the cell stack 10 in the Y-axis direction in the up-down direction.

[0059] The shape of the uneven portion 46 changes at the boundary between the passage region 42p and the passage region 42q, and changes at the boundary between the passage region 42q and the passage region 42r. The shape of the uneven portion 46 does not change in each of the passage regions 42p, 42q, and 42r.

[0060] The uneven portion 46 is provided so that, per unit distance in the refrigerant flow direction in the refrigerant passage 40, the surface area of the inner wall 47 in the passage region 42q facing the middle portion of the cell stack 10 in the Y-axis direction is larger than the surface area of the inner wall 47 in each of the passage regions 42, the passage regions 42p and 42r facing both end portions of the cell stack 10 in the Y-axis direction. The number of ribs forming the uneven portion 46 in the passage region 42q is larger than the number of ribs forming the uneven portion 46 in each of the passage regions 42, the passage regions 42p and 42r.

[0061] With this configuration, heat transfer from the battery cells 11 to the refrigerant flowing through the passage area 42q is promoted in the middle of the cell stack 10, where heat dissipation is more difficult, than at both ends of the cell stack 10, where heat dissipation is easier, thereby making it possible to cool the multiple battery cells 11 more evenly.

[0062] The uneven portion 46 is provided so that the surface area of the inner wall 47 in the passage region 42r located downstream of the refrigerant flow in the refrigerant passage 40 is larger per unit distance in the refrigerant flow direction in the refrigerant passage 40 than the surface area of the inner wall 47 in the passage region 42p located upstream of the refrigerant flow in the refrigerant passage 40. The number of ribs forming the uneven portion 46 in the passage region 42r is larger than the number of ribs forming the uneven portion 46 in the passage region 42p.

[0063] This configuration also makes it possible to suppress variations in cooling efficiency caused by differences in refrigerant temperature between the upstream and downstream sides of the refrigerant flow.

[0064] (Embodiment 3) Fig. 10 is a cross-sectional view showing a battery pack according to embodiment 3 of the present invention, which corresponds to Fig. 4 in embodiment 1.

[0065] The battery pack of the present embodiment has a structure basically similar to that of battery pack 100 of Embodiment 1. Hereinafter, description of the overlapping structure will not be repeated.

[0066] Referring to FIG. 10, the battery pack in this embodiment includes a plurality of battery cells 11, a plate member 31, and an electronic component unit 81. A cell stack 10 (10C, 10D, 10E) is formed by a plurality of battery cells 11 stacked in the Y-axis direction. The cell stack 10C, the cell stack 10D, and the cell stack 10E are spaced apart from one another and aligned in the listed order in the X-axis direction. The cell stack 10E is positioned adjacent to the case side portion 23 in the X-axis direction. The cell stack 10D is positioned between the cell stack 10C and the cell stack 10E in the X-axis direction.

[0067] The electronic component unit 81 includes a main relay, a shunt resistor, a cement resistor, a bus bar, a current sensor, etc., as well as a case that houses these electronic components. The electronic component unit 81 is housed in a case body 21. The cell stack 10C is disposed adjacent to the electronic component unit 81 in the X-axis direction. The cell stack 10C is disposed between the cell stack 10D and the electronic component unit 81 in the X-axis direction.

[0068] A refrigerant passage 40 is formed in the plate member 31. The refrigerant passage 40 includes multiple passage regions 43 (43p, 43q, 43r). The passage region 43p, the passage region 43q, and the passage region 43r are arranged in the listed order from upstream to downstream of the refrigerant flow in the refrigerant passage 40. Each of the passage regions 43p, the passage region 43q, and the passage region 43r extends in the Y-axis direction. The passage region 43p, the passage region 43q, and the passage region 43r meander along the X-axis direction while extending alternately in the +Y-axis direction and the −Y-axis direction. The passage region 43p, the passage region 43q, and the passage region 43r face the cell stack 10C, the cell stack 10D, and the cell stack 10E in the up-down direction.

[0069] The shape of the uneven portion 46 changes at the boundary between the passage region 43p and the passage region 43q, and changes at the boundary between the passage region 43q and the passage region 43r. The shape of the uneven portion 46 does not change in each of the passage regions 43p, 43q, and 43r.

[0070] The uneven portion 46 is provided so that the surface area of the inner wall 47 in the passage region 43p facing the cell stack 10C in the vertical direction is larger than the surface area of the inner wall 47 in the passage region 43r facing the cell stack 10E in the vertical direction per unit distance in the refrigerant flow direction in the refrigerant passage 40. The number of ribs forming the uneven portion 46 in the passage region 43p is larger than the number of ribs forming the uneven portion 46 in the passage region 43r.

[0071] With this configuration, in the cell stack 10C, which is more susceptible to heat dissipation from the electronic component unit 81 than the cell stack 10E, which is more susceptible to heat dissipation through the case side portion 23, heat transfer from the battery cells 11 to the refrigerant flowing through the passage area 43p is promoted, thereby making it possible to cool the multiple battery cells 11 more evenly.

[0072] The uneven portion 46 is provided so that the surface area of the inner wall 47 in the passage region 43q is smaller than the surface area of the inner wall 47 in the passage region 43p and larger than the surface area of the inner wall 47 in the passage region 43r per unit distance in the refrigerant flow direction in the refrigerant passage 40. The number of ribs forming the uneven portion 46 in the passage region 43q is smaller than the number of ribs forming the uneven portion 46 in the passage region 43p and is larger than the number of ribs forming the uneven portion 46 in the passage region 43r.

[0073] With this configuration, in cell stack 10D, which is less susceptible to heat dissipation from the electronic component unit 81 than cell stack 10C but less susceptible to heat dissipation through the case side portion 23 than cell stack 10E, the heat transfer efficiency from the battery cells 11 to the refrigerant flowing through passage region 43q can be adjusted to a ratio between the heat transfer efficiency from the battery cells 11 to the refrigerant flowing through passage region 43p and the heat transfer efficiency from the battery cells 11 to the refrigerant flowing through passage region 43r, thereby making it possible to cool the multiple battery cells 11 more evenly.

[0074] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0075] 10, 10A, 10B, 10C, 10D, 10E cell stack, 11 battery cell, 12 exterior body, 13 first side, 14 second side, 15 top surface, 16 bottom surface, 17 gas release valve, 18 electrode terminal, 18N negative electrode terminal, 18P positive electrode terminal, 21 case body, 22 case bottom, 23 case side, 24 case top, 25 heat transfer member, 31, 31A, 31B, 31C plate member, 40 refrigerant passage, 41, 41p, 41q, 41r, 41s, 42, 42p, 42q, 42r, 43, 43p, 43q, 43r passage area, 46 uneven portion, 47 inner wall, 70 internal space, 81 electronic component unit, 91 first opening area, 92 second opening area, 100 Battery pack.

Claims

1. A plurality of stacked battery cells; a plate member thermally connected to the plurality of battery cells; the plate member includes an inner wall that defines a refrigerant passage through which the refrigerant flows, the refrigerant passage is configured so that the refrigerant flows in a serpentine manner from a refrigerant inlet to a refrigerant outlet in the plate member, The inner wall is provided with an uneven portion that has a concave and / or convex shape relative to an opening of the refrigerant passage and that changes shape in the flow direction of the refrigerant in the refrigerant passage, the opening of the refrigerant passage includes a first opening region in which the uneven portion is arranged, and a second opening region located on the opposite side of the plurality of battery cells with the first opening region in between.

2. the refrigerant passage includes a first passage region and a second passage region located downstream of the first passage region in the refrigerant flow direction, 2. The battery pack according to claim 1, wherein the uneven portion is provided so that a surface area of the inner wall in the second passage region is larger than a surface area of the inner wall in the first passage region per unit distance in a flow direction of the refrigerant in the refrigerant passage.

3. a cell stack constituted by a plurality of the battery cells stacked in a predetermined direction, the refrigerant passage includes a third passage region facing an end portion of the cell stack in the predetermined direction and a fourth passage region facing an intermediate portion of the cell stack in the predetermined direction; 3. The battery pack according to claim 1, wherein the uneven portion is provided so that a surface area of the inner wall in the fourth passage region is larger than a surface area of the inner wall in the third passage region per unit distance in a flow direction of the refrigerant in the refrigerant passage.

4. a case body having a side portion; an electronic component unit housed in the case body; a first cell stack configured by a plurality of stacked battery cells and housed in the case body at a position adjacent to the side portion; a second cell stack configured by a plurality of stacked battery cells and housed in the case body at a position adjacent to the electronic component unit; the refrigerant passage includes a fifth passage region facing the first cell stack and a sixth passage region facing the second cell stack; 3. The battery pack according to claim 1, wherein the concave-convex portion is provided so that a surface area of the inner wall in the sixth passage region is larger than a surface area of the inner wall in the fifth passage region per unit distance in a flow direction of the refrigerant in the refrigerant passage.

5. the refrigerant passage includes a plurality of passage regions extending parallel to one another and connected to one another in order from the upstream side to the downstream side in the refrigerant flow direction; 3 . The battery pack according to claim 1 , wherein the shape of the concave and convex portions does not change in the flow direction of the refrigerant in the refrigerant passage in each of the passage regions and differs among the plurality of passage regions.

6. The battery pack according to claim 1 , wherein the concave and convex portions are provided along a direction in which the refrigerant flows in the refrigerant passage.

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