Battery pack structure

Abstract

The present application provides a battery pack structure capable of suppressing corrosion in a battery case. In a battery, a flange portion of an upper case and a flange portion of a lower case overlap with a seal member interposed therebetween to form a joint portion in a battery case that houses the battery pack. Also, in the joint portion, a nut is fastened by being screwed with a bolt. In a heat insulating member, the joint portion is inserted in a groove portion, and the heat insulating member is placed on a head portion of the bolt to form a prescribed gap between the joint portion and a side wall. Thus, in the battery case, water droplets are suppressed from adhering to the heat insulating member that covers the joint portion, and thus corrosion caused by contact of the heat insulating member to which the water droplets adhere is suppressed.

Description

Technical Field

[0001] This invention relates to a battery pack structure. Background Technology

[0002] Patent Document 1 discloses a sealing structure for a battery casing with a venting mechanism. In this battery casing, the peripheral portions of the lower casing component and the upper casing component overlap at their joint portions and are joined using bolts and nuts. Furthermore, a sealing member is disposed between the joint portions of the lower casing component and the upper casing component in the battery casing.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2024-060207 Summary of the Invention

[0004] In addition, vehicles equipped with an electric motor as a driving source are provided with a battery pack for storing the electricity supplied to the electric motor, and the battery pack casing (battery box) is mounted under the floor at the rear of the vehicle.

[0005] On the other hand, in vehicles that have an engine in addition to an electric motor as a driving source, the exhaust pipe extending from the engine to the rear of the vehicle is positioned near the battery casing, where the sealing components are prone to temperature rise. Therefore, a heat insulation component is provided at the joint between the upper and lower casings in the battery casing to prevent the sealing components from being heated by heat from the engine or exhaust pipe.

[0006] However, because the battery pack is located under the vehicle's floor, water droplets can easily adhere to the battery casing. These water droplets can then adhere to the heat insulation components, increasing the risk of rust forming inside the battery casing.

[0007] The present invention was made in view of the above circumstances, and its object is to provide a battery pack structure that can suppress corrosion such as rust in the battery casing.

[0008] To achieve the above objectives, the battery pack structure according to the first method includes: a battery housing, wherein a box-shaped upper housing opening downward and a box-shaped lower housing opening upward are joined at a joint where flanges protruding outward from each other's sidewalls over an overlapping portion, and the battery pack is housed internally; a sealing member, which is located between the flanges at the joint; a fastening member, which is provided at a predetermined interval at the joint and fastens the upper housing and the lower housing by screwing nuts with bolts inserted into the joint from above; and a heat insulation member, which, when disposed at the joint, has a predetermined gap between itself and the sidewall of the battery housing and covers the joint by contacting at least the head face of the bolt.

[0009] In the battery pack structure according to the first method, there is a battery housing for accommodating the battery pack. The battery housings are respectively box-shaped, and the upper housing and the lower housing are provided with flanges that protrude outward from the side wall all the way around the circumference, and are joined at the joint where the flanges overlap with each other through a sealing member.

[0010] Furthermore, fastening parts are arranged at predetermined intervals in the joint, and the fastening parts fasten the flange of the upper housing and the flange of the lower housing by screwing a nut into a bolt inserted from above into the joint.

[0011] Here, a heat-insulating component is disposed at the joint, the heat-insulating component having a predetermined gap between itself and the side wall of the battery casing, and at least contacting the head surface of the bolt to cover the joint. Therefore, even if water droplets enter between the battery casing and the heat-insulating component, water droplets can be prevented from adhering to the heat-insulating component, thereby inhibiting corrosion of the battery casing caused by water droplets adhering to the heat-insulating component.

[0012] The battery pack structure involved in the second method, in the first method, includes: a groove formed in the heat insulation component, the groove having a groove width equal to the total length of the bolt, and the bolt abutting against the bottom surface by being inserted into the engagement portion.

[0013] In the battery pack structure of the second method, a groove is formed in the heat insulation component, the width of which is the same as the total length of the bolt. The bolt abuts against the bottom surface by being inserted into the engagement portion. Therefore, since the movement of the heat insulation component toward the side wall of the battery casing is restricted, the adhesion of water droplets between the heat insulation component and the battery casing is effectively suppressed.

[0014] Invention Effects

[0015] According to the present invention, the following effects can be achieved: since the heat insulation component is mounted on the head of the bolt of the fastening part, it is possible to suppress the adhesion of water droplets or other moisture on the upper shell to the heat insulation component, thereby suppressing the decrease in durability caused by rust formation in the battery casing due to moisture adhering to the heat insulation component. Attached Figure Description

[0016] Figure 1 This is a perspective view showing the main parts of the general structure of the battery involved in this embodiment.

[0017] Figure 2 This is a cross-sectional view showing the main parts of the battery casing involved in this embodiment.

[0018] Figure 3 This indicates that the battery casing involved in this embodiment is related to... Figure 1 Sectional views of the different main parts. Detailed Implementation

[0019] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0020] In this embodiment, battery 10, which is a storage battery mounted in a vehicle, will be used as an example for explanation. Figure 1 The diagram shows a general outline of the main parts of battery 10 in a three-dimensional view. Figure 2 The diagram shows a general outline of the main components of the battery 10 in a side-view sectional view of the vehicle. Figure 3 In the middle, a cross-sectional view of the vehicle from the side shows the battery 10 and... Figure 2 A general overview of the different main parts. Additionally, in the accompanying diagram, the front of the vehicle is indicated by arrow FR, the right side in the vehicle width direction by arrow HR, and the top by arrow UP.

[0021] The vehicle equipped with battery 10 (illustration omitted) has an electric motor (electric motor) as a driving source, and battery 10 outputs DC power to drive the electric motor. Furthermore, the vehicle may also be equipped with an engine as a driving source. Hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs) are applicable to such vehicles. Additionally, battery electric vehicles (BEVs) are also applicable. In the vehicle described in this embodiment, hybrid electric vehicles (which may be plug-in hybrid electric vehicles) that have an engine in addition to an electric motor as a driving source are applicable.

[0022] like Figure 1 As shown, the battery 10 includes a battery housing 12 and a battery pack 14, with the battery pack 14 housed within the battery housing 12. In this embodiment, a battery pack structure is used within the battery housing 12 that houses the battery pack 14.

[0023] like Figure 2 and Figure 3 As shown, a floor panel 16 serving as the floor of the passenger compartment is provided in the vehicle. The battery housing 12 is disposed on the rear side of the vehicle, below the floor panel 16, and is mounted on the vehicle body (not shown). Additionally, a lower guard plate (not shown) may be provided on the underside of the battery housing 12 in the vehicle.

[0024] like Figures 1 to 3As shown, the battery housing 12 is a generally 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 side being the left side in the vehicle width direction. The battery housing 12 includes an upper housing 20 and a lower housing 22, which are respectively made of metal (e.g., steel plate).

[0025] The upper housing 20 has a top plate 24 that is generally rectangular when viewed from above. Side walls 26 protrude downwards from the outer periphery of the top plate 24, extending approximately the entire circumference of the top plate 24. Furthermore, the upper housing 20 has a flange 28 that bends outwards from the front (lower) end of the side wall 26, protruding in both the longitudinal and width directions of the vehicle. Thus, the upper housing 20 is a generally box-shaped structure with a bottom and an opening in the downward direction. Moreover, in the upper housing 20, the side walls 26 are inclined such that the opening widens, and the opening widens as the side walls move downwards (away from the top plate 24).

[0026] The lower housing 22 has a base plate 30 that is generally rectangular when viewed from above. Side walls 32 extend from the outer periphery of the base plate 30 and are formed over approximately the entire circumference of the base plate 30. Furthermore, in the lower housing 22, a flange 34 with an outwardly bent shape is formed at the front end (upper end) of the side wall 32, protruding in both the longitudinal and width directions of the vehicle. Thus, the lower housing 22 is designed as a generally box-shaped structure with a bottom and an opening at the top. Moreover, in the lower housing 22, the side wall 32 is inclined such that the opening side widens, and the side wall 32 is inclined such that the opening narrows as it approaches the base plate 30.

[0027] And, as Figure 2 and Figure 3 As shown, in the lower housing 22, a stepped portion 36 is formed in the flange portion 34 (in Figure 1 (Illustration omitted) The upper surface of the stepped portion 36 on the side wall 32 of the flange portion 34 is lower than the upper surface of the front end of the flange portion 34.

[0028] In the battery housing 12, the flange portion 34 of the lower housing 22 overlaps with the lower side of the flange portion 28 of the upper housing 20. In the battery housing 12, the flange portion 28 of the upper housing 20 and the flange portion 34 of the lower housing 22 form a joint portion 12A, which is formed throughout the circumference of the battery housing 12.

[0029] Furthermore, in the battery casing 12, fastening portions 38 are provided at multiple locations on the joint portions 12A (flange portions 28, 34). Figure 1 (Illustration omitted) Fasteners 38 are arranged at predetermined intervals on each of the joint portions 12A along the vehicle width direction and the vehicle front-to-back direction.

[0030] like Figure 2 and Figure 3 As shown, in the fastening part 38, a bolt 40 and a nut 42 are used as fastening components. In the fastening part 38, the shaft portion (threaded portion, neck) 40A of the bolt 40 is inserted from above into the through hole 44 formed in the vertical direction in each of the flange portions 28 and 34, and the nut 42 is screwed into the shaft portion 40A protruding from the through hole 44.

[0031] Thus, in the battery housing 12, in each of the fastening portions 38, the flange portions 28 and 34 are fastened by bolts 40 and nuts 42, and the upper housing 20 and lower housing 22 are fixed, with an appearance of a generally rectangular box shape. Furthermore, in the following description, the outer surfaces of the sidewalls 26 and 32 in the battery housing 12 are sometimes referred to as side surfaces.

[0032] In the battery housing 12, when the flange portion 34 of the lower housing 22 overlaps the flange portion 28 of the upper housing 20, a sealing member 46 is disposed on the stepped portion 36 of the lower housing 22. That is, in the battery housing 12, the sealing member 46 is located between the joint portions 12A. Thus, in the battery housing 12, the flange portions 28 and 34 are fastened by bolts 40 and nuts 42, and the internal space is tightly sealed by the sealing member 46.

[0033] like Figure 1 As shown, in the battery 10, the battery pack 14 is housed within the internal space of the battery casing 12. The battery pack 14 is composed of multiple (or one) battery modules 18, each of which has multiple battery cells stacked on top of it (illustration omitted).

[0034] In the battery pack 14, multiple battery modules 18 are arranged in the longitudinal and transverse directions of the vehicle. In the battery pack 14, for example, multiple battery modules 18 are connected in parallel or in series to enable the input and output (charging and discharging) of DC power at the required voltage.

[0035] In the vehicle, the battery pack 14 is connected to an inverter (not shown), which outputs power to the electric motor (during discharge) and charges the battery pack 14 (during charging) using the power input from the inverter. Furthermore, various sensors (not shown) are installed in the battery pack 14, and the charging and discharging states are controlled based on information detected by these sensors. Moreover, known structures can be used for this battery pack 14 and battery module 18.

[0036] On the other hand, in the battery 10, a heat insulation member 50 is provided at the joint portion 12A of the battery housing 12. The heat insulation member 50 is elongated, and its length direction is circumferential to the battery housing 12, and it is arranged to cover approximately the entire circumference of the upper housing 20. In addition, the heat insulation member 50 only needs to be provided at least on the front side of the battery housing 12 and on both sides in the vehicle width direction.

[0037] like Figure 2 As shown, the heat insulation member 50 has a generally rectangular cross-section, and a groove 52 is formed along the length direction on the surface of the battery housing 12 side of the heat insulation member 50. The heat insulation member 50 is disposed on the battery housing 12 by inserting the joint portion 12A into the groove 52, thereby covering the joint portion 12A.

[0038] In the heat insulation component 50, the groove width w along the vertical direction in the groove portion 52 is approximately the same as the total length L of the bolt 40 installed on the fastening portion 38. Furthermore, the total length L of the bolt 40 is expressed as the sum of the height dimension k of the head 40B (head height) and the nominal length l (thread length, neck length) which is the length dimension of the shaft portion 40A (w=L=k+l). For example, if an M8 bolt is used in the bolt 40, the head height k is set to approximately 6 mm (k≈6 mm), and the nominal length l is set to the required length.

[0039] In the heat insulation component 50, a recessed portion 54A and an embedded portion 54B are formed on the bottom surface 54 of the groove portion 52. The recessed portion 54A is formed such that when a bolt 40 and a nut 42 that engages with the bolt 40 are disposed in the groove portion 52, the head 40B of the bolt 40 and the nut 42 are embedded. Furthermore, the embedded portion 54B is formed such that when a joint portion 12A of the battery casing 12, which is fastened by the bolt 40 and the nut 42, is inserted into the groove portion 52 of the heat insulation component 50, the front end of the joint portion 12A is inserted (embedded) at the bottom of the recessed portion 54A.

[0040] In the heat insulation component 50, when the joint portion 12A covering the battery casing 12 is inserted (embedded) into the embedded portion 54B, the head 40B of the bolt 40 enters the recessed portion 54A, and the shaft portion 40A of the bolt 40 abuts against the bottom surface 54. In addition, a buffer component 16A is disposed between the heat insulation component 50 and the floor panel 16, and vibrations (vertical movement, especially upward movement) during vehicle operation, etc., in the heat insulation component 50 are suppressed by the buffer component 16A.

[0041] In this heat insulation component 50, the dimension from the opening end of the groove 52 to the bottom surface 54 is set to a predetermined depth (depth dimension) d. Furthermore, in the heat insulation component 50, the dimension between the depth d and the outer peripheral end of the through hole 44 in the joint portion 12A (the outer end of the shaft portion 40A of the bolt 40 inserted into the through hole 44) is smaller than the protrusion dimension D (d < D). Therefore, in the heat insulation component 50, when the joint portion 12A is covered by the groove 52, a predetermined gap (for example, a gap of approximately 6 mm) is formed between it and the battery casing 12.

[0042] Furthermore, in the heat insulation member 50, at the end on the battery housing 12 side, the upper side of the groove 52 is inclined along the side wall 26 of the upper housing 20, and the lower side of the groove 52 is inclined along the side wall 32 of the lower housing 22. Thus, when the groove 52 covers the joint portion 12A, the heat insulation member 50 separates from the side surface of the battery housing 12 (the outer side surface of the side wall 26 and the side wall 32) by forming the same gap (for example, a gap of about 6 mm).

[0043] On the other hand, wiring for connecting the battery pack 14 and the inverter, etc., is led out from the battery casing 12. Figure 3 The diagram shows a schematic structure of the wiring leads in the battery housing 12.

[0044] like Figure 3 As shown, in the battery housing 12, on the front side of the vehicle, the side wall 32 of the lower housing 22 is provided with a die-cast connector block 60. The connector block 60 is fastened to the lower housing 22 by bolts 56 that pass through the side wall 32 at multiple locations on its periphery.

[0045] Furthermore, a connector hole 62 is formed through the central portion of the connector block 60. Also, a through hole 32A is formed through the lower housing 22 at a position on the side wall 32 that overlaps with the connector hole 62. In the connector block 60, a connector 64, inserted into the through hole 32A of the side wall 32, is inserted and installed within the connector hole 62. A wiring 64A (one end connected to the battery pack 14) is connected to the connector 64.

[0046] Furthermore, in the connector block 60, a sealing member 66A is disposed between it and the side wall 32 to surround the entire circumference of the through hole 32A, and a sealing member 66B is disposed within the connector hole 62 to surround the entire circumference of the connector 64. Thus, the through portion of the connector 64 in the battery housing 12 is tightly sealed.

[0047] In battery 10, connector 68 is installed on connector 64 mounted on lower housing 22. Vehicle-side (inverter-side) wiring 68A is connected to connector 68. Furthermore, a fixing part 70 is formed protruding on connector 68, and connector 68 is fixed to connector block 60 by bolt 72 passing through fixing part 70 and screwed into connector block 60, and connected to connector 64.

[0048] On the other hand, when the heat insulation member 50 is disposed in the wiring lead-out portion of the battery housing 12, the lower part of the groove 52 is removed, and the portion including the recessed portion 54A and the embedded portion 54B in the bottom surface 54 of the groove 52 is also removed. As a result, the cross-section of the heat insulation member 50 (hereinafter, this part is referred to as heat insulation member 50A) is formed into an approximately L-shaped (inverted L-shaped) form by the base 74A, which is further outward than the groove 52 (on the side opposite to the battery housing 12), and the upper part 74B on the upper side of the groove 52.

[0049] In the heat insulation component 50A, the upper part 74B is placed on the head 40B of the bolt 40, thereby covering the bolt 40 and the joint portion 12A fastened by the bolt 40 from above. Furthermore, in the heat insulation component 50A, a limiting hole 76 is provided on the base 74A side of the upper part 74B, and the limiting hole 76 is formed through the upper part 74B in a vertical direction on the side of the upper part 74B closer to the base 74A than the joint portion 12A covered by the upper part 74B.

[0050] A protrusion 78 is formed on the connector block 60. The protrusion 78 protrudes from the connector block 60 toward the front side of the vehicle (opposite to the battery housing 12) above the connector hole 62, and the protruding front end extends upward. Furthermore, in the connector block 60, the front end of the protrusion 78 is inserted into the limiting hole 76 of the heat insulation member 50A. Therefore, in the heat insulation member 50A, the movement of the upper part 74B toward the battery housing 12 is restricted by the protrusion 78 of the connector block 60, and a predetermined gap (e.g., about 6 mm) is formed between the upper part 74B and the side wall 26 of the upper housing 20.

[0051] In the battery 10 configured as described above, a connector block 60 is mounted on the battery housing 12 (lower housing 22), and the connector block 60 connects the connector 64 on the battery pack 14 side to the connector 68 on the inverter side. Thus, in the battery 10, the battery pack 14 housed in the battery housing 12 is connected to the vehicle's inverter, etc., via wiring 64A, connectors 64 and 68, and wiring 68A, and the power from the battery pack 14 can be used to drive the electric motor.

[0052] In this type of vehicle, the heat from the engine located at the front of the vehicle flows along the floor panel 16 to the rear of the vehicle. Furthermore, in this vehicle, an exhaust pipe (not shown) is arranged from the engine to the rear of the vehicle, passing near the battery housing 12. Therefore, the battery housing 12 (especially the joint portion 12A) is easily heated by heat from the engine or heat released from the exhaust pipe.

[0053] In the battery casing 12, a sealing member 46 is disposed between the joint portion 12A (flange portion 28 and flange portion 34) on the side. If the sealing member 46 is unnecessarily heated, the sealing performance may be reduced.

[0054] Here, in the battery casing 12, a heat insulation member 50 is provided at the joint portion 12A on the side, and the heat insulation member 50 covers the joint portion 12A. Therefore, in the battery casing 12, it is possible to suppress the heating of the sealing member 46.

[0055] On the other hand, in the battery 10, the battery casing 12 is disposed on the underside of the floor panel 16, whereby water splashed from the road surface easily adheres to it during vehicle operation. In the battery casing 12, for example, water droplets adhering to the upper casing 20 flow along the sidewall 26 to the flange 28.

[0056] Typically, a method for mounting a heat insulation component to the battery casing 12 involves attaching double-sided tape or applying adhesive to the sidewalls 26 and 32 of the heat insulation component to bond it to the battery casing 12. In this case, if the joint of the heat insulation component deteriorates over time, the joint may peel off, creating a gap between the heat insulation component and the battery casing 12. Water droplets adhering to the battery casing 12 can then flow into this gap and adhere to the heat insulation component that contacts the flanges 28 and 34. If water droplets come into contact with the heat insulation component within the battery casing 12, rust can easily form, leading to corrosion.

[0057] In the heat insulation member 50 of this embodiment, a groove 52 is formed, the width w of which is the same as the total length L of the bolt 40 used for the engagement portion 12A. Furthermore, the bolt 40 and nut 42 (fastening portion 38) are arranged at predetermined intervals in the engagement portion 12A. Therefore, in the heat insulation member 50, when covering the engagement portion 12A of the battery housing 12 inserted into the groove 52, a gap can be formed between the head 40B of the bolt 40 and the engagement portion 12A (flange portions 28, 34).

[0058] Therefore, in the heat insulation component 50, contact with the joint portion 12A of the battery housing 12 is suppressed, and in the battery housing 12, even if water droplets that fall onto the joint portion 12A grow to a height of approximately 4 mm, they will not adhere. Thus, in the battery housing 12, corrosion caused by water droplets adhering to the heat insulation component 50 at the joint portion 12A is suppressed.

[0059] Furthermore, in the heat insulation member 50, a predetermined gap is provided between it and the battery housing 12, and the side surface of the battery housing 12 is separated from the side surface of the battery housing 12. Also, in the heat insulation member 50, when the mating portion 12A is inserted into the groove 52, the head 40B of the bolt 40 or the nut 42 abuts against the bottom of the recess 54A, or the shaft portion 40A of the bolt 40 abuts against the bottom surface 54. Therefore, in the heat insulation member 50, movement toward the side surfaces (side walls 26, 32) of the battery housing 12 is restricted by the bottom surface 54, etc.

[0060] Thus, for example, water droplets are prevented from adhering to the heat insulation component 50 and flowing down the sidewall 26. Therefore, corrosion caused by water droplets flowing along the sidewall 26 and so on adhering to the heat insulation component 50 is suppressed in the battery housing 12.

[0061] On the other hand, in the heat insulation member 50 (50A) disposed on the lead-out portion of the wiring, a limiting hole 76 is formed on the base 74A side of the upper part 74B, and the protrusion 78 of the connector block 60 is inserted into the limiting hole 76. Therefore, in the heat insulation member 50A, the movement of the upper part 74B toward the side (side wall 26) of the battery housing 12 is restricted, and contact between the upper part 74B and the side of the battery housing 12 is suppressed.

[0062] Thus, for example, water droplets are prevented from adhering to the heat insulation component 50A and flowing down the sidewall 26. Therefore, in the battery housing 12, even at the wiring lead-out points, corrosion caused by water droplets flowing along the sidewall 26 and so on adhering to the heat insulation component 50A is suppressed.

[0063] Furthermore, in the embodiment described above, the battery casing 12 that houses the battery pack 14 within the battery 10 was used as an example. However, the structure according to the present invention can be applied to any structure in which a heat-insulating member covers the joint between the upper and lower casings.

[0064] Symbol Explanation

[0065] 10-Battery, 12-Battery casing, 12A-Jointing part, 14-Battery pack, 18-Battery module, 20-Upper casing, 22-Lower casing, 26, 32-Side wall, 28, 34-Flange, 38-Fastening part, 40-Bolt, 42-Nut, 46, 66A, 66B-Sealing part, 50, 50A-Heat insulation part, 52-Groove, 54-Bottom surface, 60-Connector block, 64, 68-Connector, 76-Limiting hole, 78-Protrusion.

Claims

1. A battery pack structure, characterized in that, include: The battery casing has a box-shaped upper casing that opens downwards and a box-shaped lower casing that opens upwards, which are joined at a joint where flanges that protrude outwards from each other's side walls all around the circumference overlap, and the battery pack is housed inside. A sealing component, which is located between the flange portions at the engagement location; Fastening portions, which are provided at predetermined intervals in the engagement portion, secure the upper housing and the lower housing by engaging nuts with bolts inserted from above into the engagement portion; and A heat-insulating component, when disposed at the joint, has a predetermined gap between itself and the sidewall of the battery housing, and at least contacts the head surface of the bolt to cover the joint.

2. The battery pack structure according to claim 1, characterized in that, include: A groove is formed in the heat insulation component, the groove having a groove width equal to the total length of the bolt, and the bolt abuts against the bottom surface by being inserted into the engagement portion.

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