Battery pack structure

Abstract

To provide a battery pack structure that can suppress corrosion in the battery case. [Solution] In the battery 10, the battery case 12 that houses the battery pack has a joint portion 12A formed by overlapping the flange portion 28 of the upper case 20 and the flange portion 34 of the lower case 22 via a sealing member 46. The joint portion 12A is fastened by screwing a nut 42 onto a bolt 40. The heat insulating member 50 has a groove 52 into which the joint portion 12A is inserted and rests on the head 40B of the bolt 40, forming a predetermined gap between the joint portion 12A and the side walls 26 and 32. As a result, in the battery case 12, the adhesion of water droplets to the heat insulating member 50 covering the joint portion 12A is suppressed, and corrosion caused by contact with the heat insulating member 50 with water droplets attached is suppressed.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a seal structure of a battery case with a ventilation mechanism. In this battery case, a lower case member and an upper case member are joined together with a peripheral edge portion of one being overlapped with that of the other, and bolts and nuts are used for joining. Further, a seal member is disposed between the joining portion of the lower case member and the joining portion of the upper case member in the battery case.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a vehicle equipped with an electric motor (motor) as a driving source for running, a battery pack for storing electric power supplied to the electric motor is provided, and a battery case (battery enclosure) of the battery pack is mounted under the floor at the rear of the vehicle or the like.

[0005] On the other hand, in a vehicle equipped with an engine in addition to an electric motor as a driving source for running, an exhaust pipe extending from the engine to the rear of the vehicle is arranged to pass near the battery case. In the battery case, the temperature of the seal member is likely to rise. For this reason, a heat insulating member is disposed at the joint portion between the upper case and the lower case of the battery case so as to suppress the seal member from being heated by the heat of the engine, the exhaust pipe, or the like.

[0006] However, with battery packs, because they are located under the vehicle floor, water droplets and other substances are more likely to adhere to the battery case. In battery packs, these water droplets can adhere to the insulating material, increasing the risk of rust forming on the battery case.

[0007] This invention was made in view of the above facts, and aims to provide a battery pack structure that can suppress corrosion such as rust from occurring in the battery case. [Means for solving the problem]

[0008] To achieve the above objective, the battery pack structure according to the first embodiment includes a battery case in which a battery pack is housed, the upper case being a box-shaped body opening downward and the lower case being a box-shaped body opening upward, the upper case being joined at a joint where flange portions projecting outward from the side walls of each other around the entire circumference overlap, the upper case being a box-shaped body opening downward and the lower case being joined at a joint, the upper case being a box-shaped body opening downward and the lower case being joined at a joint, the upper case being a box-shaped body opening and the lower case being joined at a joint, and a heat insulating member that, when positioned at the joint, provides a predetermined gap between itself and the side wall of the battery case, and covers the joint, making surface contact with at least the head of the bolt.

[0009] The battery pack structure according to the first embodiment includes a battery case in which the battery pack is housed. The battery case is box-shaped and consists of an upper case and a lower case, each with flanges protruding outward from the side walls around the entire circumference, and the flanges of the two cases are joined at a joint where they are overlapped with a sealing member interposed between them.

[0010] Furthermore, fastening parts are arranged at predetermined intervals at the joint, and the flange portion of the upper case and the flange portion of the lower case are fastened together by screwing nuts onto bolts that are inserted from above at the joint.

[0011] Here, an insulating material is placed at the joint, and a predetermined gap is provided between the insulating material and the side wall of the battery case, and the insulating material covers the joint by making surface contact with at least the head of the bolt. As a result, even if water droplets enter between the battery case and the insulating material, it is possible to suppress the water droplets from adhering to the insulating material, thereby suppressing corrosion of the battery case caused by water droplets adhering to the insulating material.

[0012] The battery pack structure according to the second embodiment includes, in the first embodiment, a groove portion formed in the heat insulating member having a groove width similar to the total length of the bolt, into which the bolt abuts against the bottom surface when the joining portion is inserted.

[0013] In the battery pack structure according to the second embodiment, a groove is formed in the heat insulating member, and the groove width is the same as the total length of the bolt, so that the bolt comes into contact with the bottom surface when the joint portion is inserted. As a result, the movement of the heat insulating member toward the side wall of the battery case is restricted, so that the adhesion of water droplets that get between the heat insulating member and the battery case is effectively suppressed. [Effects of the Invention]

[0014] According to the present invention, since the heat insulating material is placed on the head of the bolt of the fastening part, it is possible to suppress moisture such as water droplets adhering to the upper case from adhering to the heat insulating material, and thus suppress the reduction in durability caused by rust forming on the battery case due to moisture adhering to the heat insulating material. [Brief explanation of the drawing]

[0015] [Figure 1] This is a perspective view of the main parts showing the schematic configuration of the battery according to this embodiment. [Figure 2] This is a cross-sectional view showing the main part of the battery case according to this embodiment. [Figure 3] This is a cross-sectional view showing a different main part of the battery case according to this embodiment than the one shown in Figure 1. [Modes for carrying out the invention]

[0016] Embodiments of the present invention will be described in detail below with reference to the drawings. In this embodiment, a battery 10 mounted on a vehicle will be used as an example. Figure 1 shows a schematic perspective view of the main part of the battery 10, Figure 2 shows a schematic cross-sectional view of the main part of the battery 10 from the side of the vehicle, and Figure 3 shows a schematic cross-sectional view of a different main part of the battery 10 from Figure 2 from the side of the vehicle. In the drawings, the front of the vehicle is indicated by the arrow FR, the right side in the vehicle width direction is indicated by the arrow HR, and the top is indicated by the arrow UP.

[0017] A vehicle (not shown) equipped with battery 10 is equipped with an electric motor as a drive source for driving, and battery 10 outputs DC power to drive the electric motor. The vehicle may also be equipped with an engine as a drive source for driving. Hybrid vehicles (HEV) and plug-in hybrid vehicles (PHEV) can be applied to such vehicles. Alternatively, electric vehicles (BEV) and the like may be applied. In this embodiment, a hybrid vehicle (which may also be a plug-in hybrid vehicle) equipped with an engine in addition to an electric motor as a drive source for driving is applied.

[0018] As shown in Figure 1, the battery 10 comprises a battery case 12 and a battery pack 14, and in the battery 10, the battery pack 14 is housed inside the battery case 12. In this embodiment, a battery pack structure is applied to the battery case 12 that houses the battery pack 14.

[0019] As shown in Figures 2 and 3, the vehicle has a floor panel 16 as the floor of the passenger compartment, and the battery case 12 is located at the rear of the vehicle, below the floor panel 16, and is attached to the vehicle body (not shown). The vehicle may also have an under cover (not shown) located below the battery case 12.

[0020] As shown in FIGS. 1 to 3, the battery case 12 has a substantially rectangular box shape, with one side being the front side of the vehicle, one of the two sides adjacent to this side being the right side in the vehicle width direction and the other being the left side in the vehicle width direction. The battery case 12 includes an upper case 20 and a lower case 22, each made of metal (for example, steel plate).

[0021] The upper case 20 includes a top plate 24 having a substantially rectangular shape in plan view, and side walls 26 project downward from the outer peripheral portion of the top plate 24. The side walls 26 are formed over substantially the entire circumference from the outer peripheral portion of the top plate 24. Further, in the upper case 20, a flange portion 28 having a shape bent outward from the tip (lower end) of the side wall 26 is formed, and the flange portion 28 projects in the vehicle longitudinal direction and the vehicle width direction. Thereby, the upper case 20 has a bottomed substantially box shape opened downward. Also, in the upper case 20, the side wall 26 is inclined so that the opening side is widened, and the side wall 26 is inclined so that the opening widens as it goes downward (away from the top plate 24).

[0022] The lower case 22 includes a bottom plate 30 having a substantially rectangular shape in plan view, and side walls 32 stand upright from the outer peripheral portion of the bottom plate 30. The side walls 32 are formed over substantially the entire circumference from the outer peripheral portion of the bottom plate 30. Further, in the lower case 22, at the tip (upper end) of the side wall 32, a flange portion 34 having a shape bent outward is formed, and the flange portion 34 projects in the vehicle longitudinal direction and the vehicle width direction. Thereby, the lower case 22 has a bottomed and open upper side substantially box shape. Also, in the lower case 22, the side wall 32 is inclined so that the opening side is widened, and the side wall 32 is inclined so that the opening narrows as it goes toward the bottom plate 30 side.

[0023] Also, as shown in FIGS. 2 and 3, in the lower case 22, a stepped portion 36 (not shown in FIG. 1) is formed on the flange portion 34, and the upper surface of the stepped portion 36 is lower than the upper surface of the tip side of the flange portion 34 on the side wall 32 side of the flange portion 34.

[0024] In the battery case 12, the flange portion 34 of the lower case 22 is superimposed on the lower side of the flange portion 28 of the upper case 20. In the battery case 12, the flange portion 28 of the upper case 20 and the flange portion 34 of the lower case 22 form a joint portion 12A, and this joint portion 12A is formed around the entire circumference of the battery case 12.

[0025] Furthermore, the battery case 12 has fastening parts 38 (not shown in Figure 1) arranged at multiple locations on the joint portion 12A (flange portions 28, 34), and the fastening parts 38 are arranged at predetermined intervals along each of the joint portion 12A that runs in the vehicle width direction and the vehicle longitudinal direction.

[0026] As shown in Figures 2 and 3, a bolt 40 and a nut 42 are used as fastening members in the fastening portion 38. In the fastening portion 38, the shaft portion (threaded portion, under the head) 40A of the bolt 40 is inserted from above into a through hole 44 formed vertically through each of the flange portions 28 and 34, and a nut 42 is screwed onto the shaft portion 40A that protrudes from the through hole 44.

[0027] As a result, in the battery case 12, the flange portion 28 and flange portion 34 are fastened together by bolts 40 and nuts 42 at each of the fastening portions 38, fixing the upper case 20 and the lower case 22, and giving the external appearance a roughly rectangular box shape. In the following description, the outer surfaces of the side walls 26 and 32 of the battery case 12 may be referred to as the sides.

[0028] In the battery case 12, when the flange portion 28 of the upper case 20 is superimposed on the flange portion 34 of the lower case 22, a sealing member 46 is positioned on the stepped portion 36 of the lower case 22. In other words, in the battery case 12, a sealing member 46 is interposed at the joint portion 12A. As a result, in the battery case 12, when the flange portions 28 and 34 are fastened with bolts 40 and nuts 42, the internal space is tightly sealed by the sealing member 46.

[0029] As shown in Figure 1, the battery 10 has a battery pack 14 housed in the internal space of the battery case 12. The battery pack 14 is composed of multiple (or one) battery modules 18, each of which has multiple battery cells (not shown) stacked on top of each other.

[0030] The battery pack 14 has multiple battery modules 18 arranged in the vehicle's front-rear direction and vehicle width direction (longitudinal and lateral directions). In the battery pack 14, for example, multiple battery modules 18 are connected in parallel or in series, enabling input and output (charging and discharging) of DC power at the required voltage.

[0031] In the vehicle, the battery pack 14 is connected to an inverter (not shown). The battery pack 14 outputs power to the motor via the inverter (during discharge) and is charged by the power input via the inverter (during charging). The battery pack 14 is also equipped with various sensors (not shown), and the charging and discharging state of the battery pack 14 is controlled based on the information detected by the sensors. Known configurations can be applied to such a battery pack 14 and battery module 18.

[0032] On the other hand, the battery 10 is provided with a heat insulating member 50 at the joint portion 12A of the battery case 12. The heat insulating member 50 is elongated, and its longitudinal direction is oriented in the circumferential direction of the battery case 12, so that it is arranged around almost the entire circumference of the upper case 20. Note that the heat insulating member 50 only needs to be arranged on both sides of the battery case 12, at least on the front side of the vehicle and in the vehicle width direction.

[0033] As shown in Figure 2, the heat insulating member 50 has a substantially rectangular cross-section, and a groove 52 is formed along the longitudinal direction on the side facing the battery case 12. The heat insulating member 50 covers the joint portion 12A by inserting the joint portion 12A into the groove 52 and placing it on the battery case 12.

[0034] The heat insulating member 50 is such that the opening width w, which is the groove width along the vertical direction in the groove portion 52, is substantially the same as the total length L of the bolt 40 attached to the fastening portion 38. Note that the total length L of the bolt 40 is expressed as the sum of the height dimension (head height) k of the head portion 40B and the nominal length (thread portion length, length below the neck) l which is the length dimension of the shaft portion 40A (w = L = k + l). Further, for the bolt 40, for example, an M8 bolt is used, the head height k is set to be approximately 6 mm (k ≒ 6 mm), and the nominal length l is set to the required length.

[0035] In the heat insulating member 50, a recessed fitting portion 54A and a fitting portion 54B are formed on the bottom surface 54 of the groove portion 52. The recessed fitting portion 54A is formed such that when the bolt 40 and the nut 42 screwed onto the bolt 40 are arranged in the groove portion 52, the head portion 40B of the bolt 40 and the nut 42 can fit therein. Further, the fitting portion 54B is formed at the bottom of the recessed fitting portion 54A such that when the joining portion 12A of the battery case 12 fastened by the bolt 40 and the nut 42 is inserted into the groove portion 52 of the heat insulating member 50, the tip of the joining portion 12A is inserted (fitted) and arranged.

[0036] When the heat insulating member 50 covers the joining portion 12A of the battery case 12, the joining portion 12A is inserted (fitted) into the fitting portion 54B, the head portion 40B of the bolt 40 enters the recessed fitting portion 54A, and the shaft portion 40A of the bolt 40 abuts against the bottom surface 54. Note that a buffer member 16A is arranged between the heat insulating member 50 and the floor panel 16, and the heat insulating member 50 is suppressed from vibrating (vertical movement, particularly upward movement) by the buffer member 16A during vehicle travel or the like.

[0037] For this heat insulating member 50, the dimension from the open end to the bottom surface 54 of the groove portion 52 is set to a predetermined depth (depth dimension) d. Further, in the heat insulating member 50, the depth d is such that the dimension between the outer peripheral end of the through hole 44 in the joining portion 12A (the outer end of the shaft portion 40A of the bolt 40 inserted into the through hole 44) is smaller than the protruding dimension D (d < D). Thereby, in the heat insulating member 50, when the joining portion 12A is covered by the groove portion 52, a predetermined gap (for example, a gap of about 6 mm) is formed between the heat insulating member 50 and the battery case 12.

[0038] Furthermore, at the end of the heat insulating member 50 on the battery case 12 side, the upper side of the groove 52 is inclined to follow the side wall 26 of the upper case 20, and the lower side of the groove 52 is inclined to follow the side wall 32 of the lower case 22. As a result, when the heat insulating member 50 covers the joint portion 12A with the groove 52, a similar gap (for example, a gap of about 6 mm) is formed between it and the side surface of the battery case 12 (the outer surface of the side wall 26 and the side wall 32), creating a separation.

[0039] Meanwhile, wiring for connecting the battery pack 14 to the inverter and the like is drawn out from the battery case 12, and Figure 3 shows a schematic configuration of the wiring outlet portion in the battery case 12.

[0040] As shown in Figure 3, in the battery case 12, a die-cast connector block 60 is positioned on the side wall 32 of the lower case 22 at the front of the vehicle. The connector block 60 is fastened and fixed to the lower case 22 by bolts 56 that are screwed through the side wall 32 at multiple points on its peripheral edge.

[0041] Furthermore, a connector hole 62 is formed through the central part of the connector block 60. In addition, a through hole 32A is formed through the side wall 32 of the lower case 22 at a position overlapping with the connector hole 62. A connector 64, which is inserted into the through hole 32A of the side wall 32, is inserted into the connector hole 62 and mounted on the connector block 60. A wiring 64A from the battery pack 14 side (one end of which is connected to the battery pack 14) is connected to the connector 64.

[0042] Furthermore, a sealing member 66A is positioned between the connector block 60 and the side wall 32 so as to surround the entire circumference of the through hole 32A, and a sealing member 66B is positioned within the connector hole 62 so as to surround the entire circumference of the connector 64. As a result, the battery case 12 is tightly sealed at the through portion of the connector 64.

[0043] In the battery 10, connector 68 is attached to connector 64 mounted on the lower case 22. The vehicle side (inverter side) wiring 68A is connected to connector 68. In addition, a fixing part 70 is formed to protrude from connector 68, and connector 68 is fixed to the connector block 60 and connected to connector 64 by a bolt 72 that passes through the fixing part 70 and is screwed into the connector block 60.

[0044] On the other hand, when the heat insulating member 50 is placed in the wiring outlet portion of the battery case 12, the lower portion of the groove 52 is removed, and the portion of the bottom surface 54 of the groove 52 that includes the recessed fitting portion 54A and the fitted portion 54B is removed. As a result, the heat insulating member 50 (hereinafter referred to as heat insulating member 50A) has a cross-section that is approximately L-shaped (inverted L-shaped) due to the base portion 74A on the outside of the groove 52 (opposite side from the battery case 12) and the upper portion 74B above the groove 52.

[0045] The insulating member 50A has an upper part 74B that rests on the head 40B of the bolt 40, thereby covering the bolt 40 and the joint 12A fastened by the bolt 40 from above. In addition, the insulating member 50A has a regulating hole 76 on the base 74A side of the upper part 74B, and the regulating hole 76 is formed to penetrate vertically through the upper part 74B on the base 74A side of the joint 12A that is covered by the upper part 74B.

[0046] The connector block 60 has a projection 78 formed on it. The projection 78 protrudes from the connector block 60 towards the front of the vehicle (opposite side from the battery case 12) above the connector hole 62, and the tip of the projection extends upward. In addition, the tip of the projection 78 of the connector block 60 is inserted into the regulating hole 76 of the heat insulating member 50A. As a result, the movement of the upper part 74B of the heat insulating member 50A toward the battery case 12 is restricted by the projection 78 of the connector block 60, and a predetermined gap (for example, about 6 mm) is formed between the upper part 74B and the side wall 26 of the upper case 20.

[0047] In the battery 10 configured in this way, a connector block 60 is attached to the battery case 12 (lower case 22), and the connector block 60 connects the connector 64 on the battery pack 14 side to the connector 68 on the inverter side. As a result, in the battery 10, the battery pack 14 housed in the battery case 12 is connected to the vehicle's inverter, etc., via wiring 64A, connectors 64, 68, and wiring 68A, and the electric motor can be driven by the power of the battery pack 14.

[0048] In such vehicles, heat from the engine located at the front of the vehicle flows to the rear of the vehicle along the floor panel 16. In addition, the vehicle has an exhaust pipe (not shown) that runs from the engine to the rear of the vehicle, and this exhaust pipe passes near the battery case 12. As a result, the battery case 12 (especially the connection area 12A) is easily heated by the heat from the engine and the heat emitted from the exhaust pipe.

[0049] In the battery case 12, a sealing member 46 is positioned between the side joint portion 12A (flange portion 28 and flange portion 34), and if the sealing member 46 is unnecessarily heated, a decrease in sealing performance is likely to occur.

[0050] In this configuration, the battery case 12 is provided with a heat insulating member 50 at the joint portion 12A on its side, and the heat insulating member 50 covers the joint portion 12A. Therefore, the battery case 12 can suppress the heating of the sealing member 46.

[0051] On the other hand, in the battery 10, the battery case 12 is located below the floor panel 16, making it easier for water splashed up from the road surface during vehicle operation to adhere to it. In the battery case 12, for example, water droplets adhering to the upper case 20 flow down the side wall 26 to the flange portion 28.

[0052] Generally, one method for attaching an insulating material to the battery case 12 is to attach the insulating material to the battery case 12 by applying double-sided tape or adhesive to the side wall 26 side and the side wall 32 side of the insulating material. In this case, if deterioration occurs over time at the joint of the insulating material, the joint may peel off, creating a gap between the insulating material and the battery case 12. Water droplets adhering to the battery case 12 will flow down this gap and adhere to the insulating material in contact with the flange portions 28 and 34. In the battery case 12, if the part of the insulating material to which water droplets have adhered is in contact, rust is likely to occur and corrosion will progress.

[0053] In this embodiment, the heat insulating member 50 has a groove 52 formed therein, and the groove width w of the groove 52 is the same as the total length L of the bolt 40 used in the joint portion 12A. The bolt 40 and nut 42 (fastening portion 38) are arranged at predetermined intervals in the joint portion 12A. Therefore, when the heat insulating member 50 covers the joint portion 12A of the battery case 12 inserted into the groove 52, it rests on the head 40B of the bolt 40, so a gap can be formed between it and the joint portion 12A (each of the flange portions 28 and 34).

[0054] As a result, the heat insulating member 50 is prevented from coming into contact with the joint portion 12A of the battery case 12, and water droplets that have flowed down to the joint portion 12A will not adhere to the battery case 12, even if they grow to a height of approximately 4 mm. Therefore, corrosion caused by water droplets from the joint portion 12A adhering to the heat insulating member 50 is suppressed in the battery case 12.

[0055] Furthermore, the heat insulating member 50 has a predetermined gap between it and the battery case 12, so that the surface facing the battery case 12 is separated from the side surface of the battery case 12. In addition, when the joint portion 12A is inserted into the groove portion 52 of the heat insulating member 50, the head 40B of the bolt 40 or the nut 42 comes into contact with the bottom of the recessed fitting portion 54A, or the shaft portion 40A of the bolt 40 comes into contact with the bottom surface 54. As a result, the movement of the heat insulating member 50 toward the side surface (side walls 26, 32) of the battery case 12 is restricted by the bottom surface 54, etc.

[0056] As a result, the adhesion of water droplets, for example, that flow down the side wall 26 to the heat insulating member 50 is suppressed. Therefore, corrosion caused by water droplets flowing down the side wall 26 and the like adhering to the heat insulating member 50 in the battery case 12 is suppressed.

[0057] On the other hand, the heat insulating member 50 (50A) positioned at the wiring outlet has a regulating hole 76 formed on the base 74A side of the upper part 74B, into which the projection 78 of the connector block 60 is inserted. As a result, the movement of the upper part 74B toward the side (side wall 26) of the battery case 12 is restricted in the heat insulating member 50A, preventing the upper part 74B from coming into contact with the side of the battery case 12.

[0058] As a result, the adhesion of water droplets, for example, that flow down the side wall 26 to the heat insulating member 50A is suppressed. Therefore, in the battery case 12, corrosion caused by water droplets flowing down the side wall 26 etc. and adhering to the heat insulating member 50A is suppressed even at the wiring outlet area.

[0059] In the embodiment described above, the battery case 12 housing the battery pack 14 was used as an example in the battery 10. However, the configuration according to the present invention can be applied to any configuration in which the joint between the upper case and the lower case is covered with a heat insulating material. [Explanation of symbols]

[0060] 10 batteries 12 Battery Cases 12A Joint site 14 Battery Pack 18 Battery Modules 20 Upper Cases 22 Lower Cases 26, 32 side wall 28, 34 Flange section 38 Fastening section 40 volts 42 nuts 46, 66A, 66B sealing members 50, 50A insulation material 52 Groove 54 Bottom 60 Connector Blocks 64, 68 connectors 76 Restriction holes 78 Protrusion

Claims

1. A battery case is formed by joining a box-shaped upper case with an opening facing downwards and a box-shaped lower case with an opening facing upwards at a joint where flange portions that protrude outwards from the side walls of each other around the entire circumference overlap, and a battery pack is housed inside. A sealing member interposed between the flange portions at the joint, A fastening portion is provided at predetermined intervals in the aforementioned joint portion, and a nut is screwed onto a bolt inserted into the aforementioned joint portion from above, thereby fastening the upper case and the lower case together. When positioned at the aforementioned joint, a predetermined gap is provided between it and the side wall of the battery case, and a heat insulating member is provided that covers the joint and is in surface contact with at least the head of the bolt. A battery pack structure that includes this.

2. The battery pack structure according to claim 1, wherein the heat insulating member has a groove width similar to the total length of the bolt, and the bolt abuts against the bottom surface when the joint portion is inserted.

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