Battery pack construction

Abstract

A battery pack structure includes a battery module configured to include a plurality of battery cells arranged side by side in a prescribed direction and an end plate arranged outside the arrangement direction of the plurality of battery cells, a lower case that houses a lower portion of the battery module, and a module bracket that fixes the end plate to the lower case in a manner that forms a gap between the module bracket and an inner wall surface of the lower case, has a bending point that bends toward the end plate at a portion opposite the end plate, and further has an abutting surface that extends from the bending point along the end plate and opposes the end plate.

Description

Technical Field

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

[0002] An example of a battery module fixing structure is disclosed in Japanese Patent Application Publication No. 2018-073542.

[0003] To put it simply, in this battery module fixing structure, by studying the shape of the end plate and side plate, the load variation caused by the temperature change of the individual cells and the expansion and contraction caused by years of deterioration is not transmitted to the module fixing point. Summary of the Invention

[0004] However, the technology described in Japanese Patent Application Publication No. 2018-073542 has room for improvement in the following aspects. Specifically, while it is necessary to effectively utilize the load in the stacking direction of the modules to simplify the energy absorption mechanism during a collision, the connection between the lower housing and the module becomes low-rigidity in this configuration. That is, the connection from the module's mounting point to the individual cells is low-rigidity. Therefore, it is difficult to transfer external collision loads to the module.

[0005] The present invention takes into account the above facts and aims to obtain a battery pack structure that can connect the battery module to the lower housing with low rigidity when the battery is in use and connect the battery module to the lower housing with high rigidity in the event of a collision.

[0006] The battery pack structure of the present invention described in Scheme 1 includes: a battery module comprising a plurality of battery cells arranged side by side in a predetermined direction, and an end plate disposed outside the arrangement direction of the plurality of battery cells; a lower housing housing the lower part of the battery module; and a module bracket that fixes the end plate to the lower housing in such a way that a gap is formed between the bracket and the inner wall surface of the lower housing, and has a bending point that bends toward the end plate in the portion opposite to the end plate, and also forms an abutment surface that extends from the bending point along the end plate and opposes the end plate.

[0007] According to the invention described in Scheme 1, the end plate of the battery module is fixed to the lower housing via a module bracket, and a bending point is provided on the opposing portion of the module bracket opposite to the end plate, bending towards the end plate side. Therefore, during normal use of the battery pack, load variations caused by the expansion and contraction of individual battery cells are absorbed through the displacement of the bending point, making it difficult to transmit to the fixing point between the module bracket and the lower housing. That is, the fixing structure of the battery module is made less rigid.

[0008] On the other hand, the portion of the module bracket opposite the end plate has an abutment surface extending from the bending point along the end plate and opposing it. Therefore, if an impact load is input from the module bracket side to the end plate side during a collision, the abutment surface first abuts against the end plate, thereby rigidly connecting the battery module and the lower housing via the module bracket and rapidly generating a reaction force relative to the impact load. That is, the state of rigid connection between the battery module and the lower housing can be reproduced during a collision.

[0009] In the battery pack structure of the present invention described in Scheme 2, in the invention described in Scheme 1, a protrusion protruding toward the lower housing is provided in the end plate at a position opposite to the lower housing.

[0010] According to the invention described in Scheme 2, since a protrusion protruding towards the lower housing is provided in the end plate at a position opposite to the lower housing, the lower housing deforms and comes into contact with the protrusion upon impact. Therefore, a reaction force can be generated from the end plate towards the lower housing via the protrusion. As a result, a reaction force can be rapidly generated at the protrusion in addition to the contact surface.

[0011] In the battery pack structure of the present invention described in Scheme 3, in the invention described in Scheme 2, a protrusion protruding toward the end plate side is provided in the lower housing at a position opposite to the protrusion.

[0012] According to the invention described in Scheme 3, a protrusion protruding towards the end plate is provided in the lower housing at a position opposite to the protrusion provided on the end plate. Therefore, the distance between the protrusion and the protrusion is shorter than in the part without the protrusion. Thus, upon impact, the protrusion of the lower housing and the protrusion of the end plate quickly come into contact, generating a reaction force. Therefore, upon impact, a collision reaction force can be rapidly generated outside the battery pack. For example, if an energy-absorbing member is disposed outside the lower housing, the reaction force can be rapidly applied to the energy-absorbing member, causing it to undergo plastic deformation.

[0013] In the battery pack structure of the present invention described in Scheme 4, and in the invention described in Scheme 3, a reinforcing rib is provided on the opposing surface of the end plate that is opposite to the lower housing, and the reinforcing rib connects the fixing part that fixes the end plate and the lower housing to the protrusion.

[0014] According to the invention described in Scheme 4, since a reinforcing rib connecting the fixing part and the protrusion is provided on the opposing surface of the end plate opposite to the lower housing, the impact load input during the collision is distributed to the whole end plate through the reinforcing rib.

[0015] As described above, the battery pack structure of the present invention described in Scheme 1 has the following excellent effects: it can connect the battery module to the lower housing with low rigidity when the battery is in use, and connect the battery module to the lower housing with high rigidity in the event of a collision.

[0016] The battery pack structure described in Scheme 2 has the following excellent effects: it can increase the portion that generates reaction force during a collision, thereby enhancing the high rigidity characteristics required during a collision.

[0017] The battery pack structure described in Scheme 3 of the present invention has the following excellent effect: it can improve the energy absorption performance during collision.

[0018] The battery pack structure described in Scheme 4 has the following excellent effect: it can quickly generate a collision reaction force while suppressing the input of collision loads to the battery cell side. Attached Figure Description

[0019] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, in which the same reference numerals denote the same elements, and wherein:

[0020] Figure 1 This is a schematic longitudinal sectional view showing the overall structure of the battery pack structure involved in this embodiment cut along the vehicle width direction;

[0021] Figure 2 yes Figure 1 An enlarged cross-sectional view of the main components of the battery pack structure shown;

[0022] Figure 3 yes Figure 1 An enlarged front view of the end plate shown; and

[0023] Figure 4 It means to Figure 2 The main components of the battery pack shown are shown in a cross-sectional view along line 4-4. Detailed Implementation

[0024] The following uses Figures 1 to 4 The battery pack structure involved in this embodiment will be described. Furthermore, in these figures, arrow UP appropriately indicates the upper side of the vehicle, arrow LH indicates the left side in the vehicle width direction, and arrow FR indicates the front side of the vehicle.

[0025] Overall structure of the battery pack

[0026] Figure 1This is a schematic longitudinal sectional view showing the overall structure of the battery pack according to this embodiment, cut along the vehicle width direction. As shown in the figure, a battery pack 12, which is generally rectangular in shape when viewed from above, is disposed on the lower side of the vehicle compartment (the side below the vehicle floor). Furthermore, an elongated energy-absorbing member 14, with its length along the vehicle's longitudinal direction, is disposed on the outer side of the battery pack 12 in the vehicle width direction. Additionally, in... Figure 1 The diagram only shows the energy absorption member 14 on the left side of the battery pack 12 in the vehicle width direction, but the same energy absorption member is also provided on the right side of the battery pack 12 in the vehicle width direction. The energy absorption member 14 has a rectangular closed cross-sectional shape and forms two partition walls inside. As an example, the energy absorption member 14 is made of extruded material.

[0027] like Figure 1 and Figure 2 As shown, the battery pack 12 includes a plurality of battery modules 20, each battery module 20 comprising a plurality of battery cells 16 stacked in a predetermined direction and an end plate 18 disposed at the end of the stacking direction.

[0028] The aforementioned multiple battery modules 20 are housed in the housing 22. The housing 22 is configured to include a lower housing 26 with a cap-shaped cross-section forming the lower part of the housing 22, and an upper housing (not shown) fitted into the lower housing 26 and forming the upper part of the housing 22.

[0029] Furthermore, the lower housing 26 is configured to include a main body portion 26A with a cap-shaped cross-section and a reinforcing member 26B with a generally Z-shaped cross-section formed by a rectangular closed cross-section structure with a side wall portion 26A1 and a bottom wall portion 26A2 located outside the vehicle width direction of the main body portion 26A.

[0030] The main components of the battery pack structure

[0031] The aforementioned battery module 20 is mounted to the reinforcing member 26B of the lower housing 26 via the module bracket 24. Specifically, as... Figure 2 As shown, the module bracket 24 is L-shaped when viewed in the vehicle's longitudinal direction, and consists of a transverse wall portion 24A extending along the vehicle's width direction, and a longitudinal wall portion 24B that bends from the inner end of the transverse wall portion 24A toward the vehicle's upper side and extends in the vehicle's vertical direction. The transverse wall portion 24A is fastened to the horizontal flange portion 26B1 of the reinforcing member 26B by a first bolt 30A and a weld nut (not shown). Furthermore, the longitudinal wall portion 24B is fastened to the boss 31 formed on the side of the end plate 18 by a second bolt 30B.

[0032] Here, the longitudinal wall portion 24B of the aforementioned module bracket 24 is temporarily bent obliquely downward toward the end plate 18 at a predetermined position at its lower part, and then bends downward along the side of the end plate 18 toward the bottom wall portion 26A2 of the lower housing 26. Hereinafter, the endpoint of the aforementioned oblique downward bend will be referred to as the "bending point 32", and the inner wall surface that bends downward from this bending point 32 will be referred to as the "abutment surface 34". The abutment surface 34 is positioned opposite the center portion of the side of the end plate 18 with a small gap between them.

[0033] In addition, such as Figures 1 to 3 As shown, a plurality of cylindrical protrusions 36 are integrally formed at predetermined intervals on the lower part of the outer side of the end plate 18 in the vehicle width direction. The protrusions 36 are preferably solid, but can also be hollow. Furthermore, the shape of the protrusions 36 is not limited to cylindrical; they can also be prismatic. In this embodiment, protrusions 36 are formed at a total of three locations: the front and rear end sides and the central side of the end plate 18. The protrusion height of the protrusions 36 is set to be the same as that of the boss 31, and their size is also set to be approximately the same.

[0034] Furthermore, a generally lattice-shaped reinforcing rib 38 extending longitudinally and laterally is integrally formed on the outer side of the end plate 18 in the vehicle width direction. Three protrusions 36 are interconnected by the reinforcing ribs 38. In addition, four bosses 31 are also interconnected by the reinforcing ribs 38. That is, multiple protrusions 36 and bosses 31 are interconnected by the reinforcing ribs 38.

[0035] like Figure 4 As shown, the vertical wall 26B2 of the reinforcing member 26B in the lower housing 26 is formed into a concave-convex shape when viewed in a top cross-sectional view. Consequently, a protrusion 42 is positioned close to the protrusion 36 in the vehicle width direction on the vertical wall 26B2. A small gap 44 is provided between the top of the protrusion 42 and the end face of the protrusion 36. However, the gap 44 is set wider than the gap between the abutment surface 34 and the end plate 18.

[0036] Functions and effects

[0037] Next, the function and effects of the battery pack structure involved in this embodiment will be explained.

[0038] According to this embodiment, the end plate 18 of the battery module 20 is fixed to the lower housing 26 via the module bracket 24, and a bending point 32 is provided in the part of the module bracket 24 opposite to the end plate 18, which bends toward the end plate 18.

[0039] Therefore, during normal use of the battery pack 12, the load variations caused by the expansion and contraction of the battery cells 16 are absorbed through the displacement of the bending point 32 and are difficult to transmit to the first bolt 30A between the module bracket 24 and the lower housing 26. That is, the fixing structure of the battery module is made less rigid.

[0040] On the other hand, the portion of the module bracket 24 opposite to the end plate 18 has an abutment surface 34 extending from the bend point 32 along the end plate 18 and opposite to the end plate 18.

[0041] Therefore, if the collision load F is input from the module bracket 24 side to the end plate 18 side during the collision, the contact surface 34 will first contact the end plate 18. Figure 3 The reinforcing ribs 38 (represented by dots) abut against each other, thereby rigidly connecting the battery module 20 and the lower housing 26 via the module bracket 24, rapidly generating a reaction force relative to the collision load F1. That is, in the event of a collision, the state of the battery module and the lower housing being rigidly connected can be reproduced.

[0042] As explained above, the battery pack structure of this embodiment can connect the battery module 20 to the lower housing 26 with low rigidity when the battery is in use, and connect the battery module 20 to the lower housing 26 with high rigidity when a collision occurs.

[0043] Furthermore, in this embodiment, a protrusion 36 protruding towards the lower housing 26 is provided in the end plate 18 at a position opposite to the lower housing 26. Therefore, upon impact, the lower housing 26 deforms and contacts the protrusion 36, and an impact load F2 is input. This allows a reaction force to be generated from the end plate 18 towards the lower housing 6 via the protrusion 36. As a result, in addition to the contact surface 34, a reaction force can also be rapidly generated at the protrusion 36. Consequently, the battery pack structure according to this embodiment increases the portion that generates a reaction force upon impact, enhancing the high rigidity characteristics required during impact.

[0044] Furthermore, in this embodiment, a protrusion 42 protruding toward the end plate 18 is provided in the lower housing 26 at a position opposite to the protrusion 36 provided on the end plate 18, so the distance between the protrusion 42 and the protrusion 36 is shorter than that in the part without the protrusion 42.

[0045] Therefore, upon impact, the protrusion 42 of the lower housing 26 rapidly abuts against the protrusion 36 of the end plate 18, generating a reaction force. Thus, a collision reaction force can be rapidly generated outside the battery pack 12 upon impact. For example, if an energy absorption member 14 is disposed outside the lower housing 26, the reaction force can rapidly act on the energy absorption member 14, causing it to undergo plastic deformation. As a result, the battery pack structure of this embodiment improves energy absorption performance upon impact.

[0046] Furthermore, in this embodiment, a reinforcing rib 38 is provided on the opposing surface of the end plate 18 opposite to the lower housing 26, connecting the boss 31 and the protrusion 36. Therefore, the impact load F input during a collision is dispersed along the entire surface of the end plate 18 via the reinforcing rib 38. As a result, the battery pack structure according to this embodiment can quickly generate a collision reaction force while suppressing the input of the impact load F to the battery cell 16 side.

[0047] Supplementary Description of Implementation Methods

[0048] Furthermore, in the above-described embodiment, the bending point 32 and the contact surface 344 formed on the module bracket 24 are formed at one place, but it is not limited to this. The bending point can be formed at multiple places on the module bracket, or multiple bending points can be provided on one contact surface.

[0049] In addition, in this embodiment, the protrusion 36 is formed in three cylindrical locations on the end plate 18, but it is not limited to this. The protrusion may be formed in multiple locations other than one or three, and the shape may be other than cylindrical as described above.

[0050] Furthermore, in this embodiment, the reinforcing rib 38 is set in a grid shape, but it is not limited to this and can also be formed in a beveled shape or a honeycomb shape.

Claims

1. A battery pack structure having: A battery module is configured to include a plurality of battery cells arranged side by side in a predetermined direction and an end plate disposed outside the arrangement direction of the plurality of battery cells. The lower housing, which houses the lower part of the battery module; and The module bracket secures the end plate to the lower housing in such a way that it forms a gap with the inner wall surface of the lower housing, and has a bending point that bends toward the end plate in the portion opposite to the end plate, and also forms an abutment surface that extends from the bending point along the end plate and is opposite to the end plate.

2. The battery pack structure according to claim 1, wherein, A protrusion is provided in the end plate at a position opposite to the lower housing, protruding toward the lower housing.

3. The battery pack structure according to claim 2, wherein, A protrusion protruding toward the end plate side is provided in the lower housing at a position opposite to the protrusion.

4. The battery pack structure according to claim 3, wherein, A reinforcing rib is provided on the opposing surface of the end plate opposite to the lower housing. The reinforcing rib connects the fixing part that fixes the end plate and the lower housing to the protrusion.

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