Battery pack

Abstract

The invention provides a battery pack capable of suppressing water immersion into the battery pack. The battery pack includes: an upper case body; the upper shell is provided with an upper shell flange arranged at the end part of an upper shell main body part; and a lower case disposed below the upper case and having a lower case flange provided at an end portion of a lower case main body portion, the bending load at which the upper case flange begins to deform being weaker than the peel strength at which the adhesive inserted into the gap between the upper case flange and the lower case flange begins to peel when the upper case flange and the lower case flange are fixed.

Description

Technical Field

[0001] This invention relates to battery packs. Background Technology

[0002] In recent years, battery packs have been developed that house battery modules containing multiple battery cells within a housing. This housing is formed by connecting a lower housing and an upper housing.

[0003] Patent document 1 describes the following: a protrusion protruding to the lower housing side is provided on the flange of the upper housing, and a sealing material made of polyurethane resin adhesive is filled in the gap between the flange of the upper housing and the flange of the lower housing.

[0004] At this point, the sealing material is filled at a position closer to the inside of the battery housing than the protrusions on the upper housing, making close contact with each flange of the upper and lower housings. Then, the sealing material cures while bonded to each flange, sealing the gaps between the flanges of the upper and lower housings.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2023-046615

[0006] In the battery casing disclosed in Patent Document 1, the flanges provided on the upper and lower casings have high rigidity, meaning that flange deformation is not anticipated. Therefore, in the event of an external force such as a collision, it is assumed that the adhesive will peel off and the bonded portion will be destroyed in the gaps between the flanges. In this case, in an environment where moisture exists outside the battery pack, there is a possibility that water could seep into the inside of the battery pack where the battery modules or devices are located. Summary of the Invention

[0007] This invention provides a battery pack that inhibits water from seeping into the battery pack.

[0008] The battery pack of the present invention comprises: an upper housing having an upper housing body portion and an upper housing flange disposed at an end of the upper housing body portion; and a lower housing disposed below the upper housing and having a lower housing body portion and a lower housing flange disposed at an end of the lower housing body portion, wherein the bending load of the upper housing flange is weaker than the peeling load of the adhesive inserted in the gap between the upper housing flange and the lower housing flange when the upper housing flange and the lower housing flange are fixed.

[0009] Therefore, when an external force is applied, it can prevent the adhesive from peeling off while the flange itself deforms and the bonded part is damaged.

[0010] According to the present invention, a battery pack that inhibits water ingress into the battery pack can be provided. Attached Figure Description

[0011] The above-mentioned objects, other objects, features and advantages of this disclosure will be more fully understood through the detailed description and accompanying drawings provided below.

[0012] Figure 1 This is a side view showing a structural example of the battery pack according to Embodiment 1.

[0013] Figure 2A This is an enlarged side view showing the state of an external force applied to the flange according to Embodiment 1.

[0014] Figure 2B This is an enlarged side view showing the state of an external force applied to the flange according to Embodiment 1.

[0015] Figure 3A This is a side view showing the state in which a curved portion is provided on the upper housing flange according to Embodiment 1.

[0016] Figure 3B This is a side view showing the state in which a curved portion is provided on the upper housing flange according to Embodiment 1.

[0017] Figure 4 This is a side view of the battery pack with the EA component and reinforcement involved in Embodiment 1 installed.

[0018] Figure 5 This is a perspective view of the reinforcement component involved in Implementation Method 1.

[0019] Figure 6 This is a side view of the battery pack in the state where an external force has been applied to component EA of Embodiment 1. Detailed Implementation

[0020] Implementation Method 1

[0021] The battery pack of this embodiment will be described below with reference to the accompanying drawings. Figure 1 This is a schematic diagram illustrating a structural example of battery pack 1.

[0022] like Figure 1 As shown, the battery pack 1 includes an upper housing 11 and a lower housing 12. Here, as... Figure 1 As shown, the battery pack 1 is positioned relatively long in the X direction. The upper housing flange 11b and lower housing flange 12b, described later, are respectively located at their ends in the X direction. Furthermore, the case where the upper housing 11 is positioned on the upper side in the Z direction and the lower housing 12 is positioned on the lower side in the Z direction, and they are joined together, will be explained. The X, Y, and Z directions are mutually orthogonal.

[0023] The upper housing 11 includes an upper housing body portion 11a and an upper housing flange 11b. The upper housing flange 11b is formed at both ends in the X direction of the upper housing body portion 11a.

[0024] The lower housing 12 has a lower housing body portion 12a and a lower housing flange 12b. The lower housing flange 12b is formed at both ends in the X direction of the lower housing body portion 12a.

[0025] The upper housing body 11a is disposed opposite to the lower housing body 12a in the Z direction. In the following text, the upper housing body 11a and the lower housing body 12a are referred to together as the body 21.

[0026] The upper housing flange 11b is disposed opposite to the lower housing flange 12b in the Z direction. Furthermore, in the following description, the upper housing flange 11b and the lower housing flange 12b together constitute a flange portion 22, which is provided at both ends of the main body portion 21 in the X direction. Additionally, in the X direction, the portions near the front ends of the upper housing flange 11b and the lower housing flange 12b that are fastened together constitute fastening portions 23.

[0027] Furthermore, in the following text, the space formed between the upper housing body portion 11a and the lower housing body portion 12a is referred to as the receiving portion 13, and the space formed between the upper housing flange 11b and the lower housing flange 12b is referred to as the gap 14. In addition, the upper housing flange 11b and the lower housing flange 12b are joined and sealed within the gap 14 by an adhesive 15.

[0028] Furthermore, the receiving portion 13 and the gap 14 are an integral space. Therefore, at the X-direction end of the flange portion 22 of the battery pack 1, the upper housing flange 11b and the lower housing flange 12b are fastened by the fastening portion 23 to prevent positional displacement, and the gap 14 is sealed by the adhesive 15, thereby enabling the receiving portion 13 to be in a sealed state.

[0029] The main body 21 has sufficient length in the X, Y, and Z directions. Therefore, the storage section 13, which serves as the space within the main body 21, has sufficient length in the X, Y, and Z directions to accommodate devices such as battery modules and relays. Here, the main body 21 is a roughly rectangular parallelepiped extending along the X direction, but a detailed example of its shape will be described later.

[0030] Furthermore, the flange portion 22 is shorter than the main body portion 21 in the X, Y, and Z directions, respectively. Moreover, the flange portion 22 is longer in the X direction than in the Y and Z directions.

[0031] Here, the bending stiffness of the upper housing flange 11b is weaker than the peel strength of the adhesive 15. In other words, the bending load at which the upper housing flange 11b begins to deform is weaker than the peel strength at which the adhesive 15 begins to peel off. Specifically, in the flange portion 22, the plate thickness forming the upper housing flange 11b is sufficiently thinned to reduce stiffness. Thus, in the flange portion 22, the condition can be satisfied that the peel load generated by the adhesion of the adhesive 15 is greater than the bending load of the upper housing 11.

[0032] In this state, when an external force is applied to the flange portion 22, the upper housing flange 11b deforms in accordance with the deformation of the lower housing flange 12b. Therefore, excessive force can be suppressed on the adhesive 15 filling the gap 14 in the flange portion 22, thus preventing the adhesive 15 from peeling off. It should be noted that the reduction in rigidity of the upper housing 11, the adhesive force of the adhesive 15, and the following deformation will be described in detail below.

[0033] Furthermore, since the lower housing 12 is a component that supports the lower part of the battery module and other equipment housed in the housing 13, it requires high strength and high rigidity. On the other hand, since the upper housing 11 covers the battery module and other equipment housed in the housing 13, its rigidity can be reduced. Therefore, the upper housing 11 can have a structure that reduces the rigidity of both the upper housing body 11a and the upper housing flange 11b.

[0034] Next, the specific state when an external force is applied to the flange 22 will be explained. Figure 2A and Figure 2B This is an enlarged view showing the flange 22 in a state where an external force of tens of N is applied to it, causing it to deform according to the gap 14 provided inside. Figure 2A The battery pack 1 of the present invention is an example of a state in which the rigidity of the upper housing 11 is reduced. Figure 2B This is an example of a battery pack with a high degree of rigidity in the upper housing 11. In either case, an adhesive 15 is inserted into the gap 14 within the flange portion 22, and the adhesive 15 is bonded to the upper housing flange 11b and the lower housing flange 12b.

[0035] Here, we assume that due to collisions, etc. Figure 2A and Figure 2B A large load of tens of kN is applied to the flange portion 22 shown. Here, the external force is applied from the upper housing flange 11b side to the lower housing flange 12b side, that is, downward.

[0036] like Figure 2BAs shown, if the upper housing flange 11B has a bending stiffness higher than the peel strength of the adhesive 15, the gap 14 widens because the deformation states of the upper housing flange 11B and the lower housing flange 12B are inconsistent. Therefore, typically, the adhesive 15 is in a state of peeling off from one of the upper housing flange 11B and the lower housing flange 12B.

[0037] On the other hand, such as Figure 2A As shown, the upper housing flange 11b has a lower bending stiffness than the peel strength of the adhesive 15. Therefore, the upper housing flange 11b easily deforms following the lower housing flange 12b. Thus, the adhesive 15 can maintain its bond to both the upper housing flange 11b and the lower housing flange 12b.

[0038] Next, refer to Figure 3A and Figure 3B An example in which a curved portion 31 is provided on the upper housing flange 11B will be described.

[0039] like Figure 3A As shown, the upper housing flange 11b has a bent portion 31, a first flange portion 32, and a second flange portion 33. Here, the bent portion 31 is disposed between the first flange portion 32 and the second flange portion 33.

[0040] Specifically, the first flange portion 32 is provided on the end side of the upper housing flange 11b in the X direction, and is configured such that the distance between it and the lower housing flange 12b is shorter. On the other hand, the second flange portion 33 is provided in the X direction closer to the upper housing body portion 11a than the first flange portion 32. Here, the second flange portion 33 is configured such that the distance between the second flange portion 33 and the lower housing flange 12b is longer than the distance between the first flange portion 32 and the lower housing flange 12b. Therefore, in the upper housing flange 11b, by having the bend portion 31, it can be said that the first flange portion 32 and the second flange portion 33 are separated.

[0041] In this way, a portion with a larger radius (R), i.e., a bending portion 31, can be prepared in advance in the upper shell flange 11b. As a result, the upper shell flange 11b is more easily deformed when subjected to external forces.

[0042] Furthermore, the adhesive 15 is injected into the gap 14 of the first flange portion 32. That is, in the flange portion 22, in the X direction, the portion where the adhesive 15 is inserted and the gap 14 is sealed is on the outer side compared to the bent portion 31. As a result, in the battery pack 1, when an external force is applied to the flange portion 22, the torque length from the main body portion 21 to the adhesive 15 becomes longer, and deformation becomes easier.

[0043] Figure 3BThis is an enlarged view illustrating, as an example, the state in which an external force is applied to the flange portion 22, where a bending portion 31 is provided on the upper housing flange 11B. Figure 3B In the diagram, a solid line indicates an example where the bend 31 is not provided, and a dotted line indicates an example where the bend 31 is provided.

[0044] Furthermore, the upper shell 11 and the lower shell 12 are each formed of steel plate. As an example of dimensions, the thickness of the steel plate used for the upper shell 11 is approximately t = 0.6 mm, and the thickness of the steel plate used for the lower shell 12 is approximately t = 1.0 mm. Here, the thickness of the upper shell 11 is reliably less than the thickness of the lower shell 12.

[0045] Adhesive 15 is disposed on the first flange portion 32 within the gap 14. As an example, when the length of the main body portion 21 in the X direction is formed to be about 200 mm, adhesive 15 is applied to a portion at a distance of about 15 mm from the end of the main body portion 21 in the X direction.

[0046] Here, adhesive 15 can be a polyurethane adhesive, and the peel load is approximately 2.0 N / mm. The deformation load F of the upper shell 11 is based on a yield stress of 150 MPa. Therefore, if we solve the equation 150 = F(N) × 15 / (1 / 6 × 1 × 0.6^2), then F = 0.6 N / mm.

[0047] That is, relative to the bending load of 0.6 N / mm required for the upper shell to bend, the peel load required for the adhesive 15 to peel off is 2.0 N / mm, which means the peel load is higher than the bending load of the upper shell. As an example, the peel load is at least twice the bending load of the upper shell. Therefore, even when a load of several kN or more is applied relative to the flange 22 caused by external forces such as impact, the adhesive 15 will not peel off, and the upper shell 11 will deform in accordance with the lower shell 12.

[0048] Further reference Figures 4-6 This illustrates an example of a state in which an external force is applied to battery pack 1. Figure 4 This diagram shows the state in which the EA (Energy Absorption) component 2, formed of aluminum extrusion material or the like, is mounted on the battery pack 1. Furthermore, the battery pack 1 and the EA component 2 are connected via a connecting fastener 3. In this case, the battery pack 1 is used in a vehicle, and the EA component 2 is joined to the door sill interior of the vehicle body.

[0049] like Figure 4As shown, in battery pack 1, the lower housing flange 12b is made longer than the upper housing flange 11b. The upper housing flange 11b and the lower housing flange 12b are fastened by fastening part 23, and the gap 14 inside the fastening part 23 is sealed by adhesive 15.

[0050] Here, Figure 5 This is an example showing the appearance of the reinforcement member 3. A partially recessed recess 3a is formed in the upper part of the reinforcement member 3, where fastening components such as nuts can be installed. In addition, multiple spot weld points 3b are provided at the lower end and multiple spot weld points 3c are provided at the upper end in the Z direction on the reinforcement member 3.

[0051] Figure 4 An example is shown where spot weld 3b of the reinforcement 3 is joined to the lower part of the lower housing body 12a and spot weld 3c is joined to the lower part of the lower housing flange 12b.

[0052] Here, the engagement of EA part 2 and reinforcement part 3 will be described. EA part 2 is shaped to extend along the X direction and engages with reinforcement part 3 near the main body 21. Furthermore, EA part 2 is engaged using a fastening member, such as a bolt or nut, provided in the recess 3a of reinforcement part 3. Typically, the engagement point of EA part 2 and reinforcement part 3 is below the lower housing flange 12b. Moreover, the fastening part between EA part 2 and reinforcement part 3 is reinforcement fastening part 41.

[0053] That is, a portion of the reinforcement 3 is configured to be clamped between the EA part 2 and the lower housing flange 12b, and fastened by bolts passing through the EA part 2 and the reinforcement 3.

[0054] Next, the connection between EA part 2 and the door sill inner part 4 will be described. With the door sill inner part 4 positioned above EA part 2, EA part 2 and door sill inner part 4 are connected in the X direction at a point further forward than the flange 22.

[0055] As an example, an EA part collar 2a is provided at the front end of EA part 2 in the X direction. A bolt that is long in the Z direction passes through the EA part collar 2a and is fastened when it reaches the lower part of the door sill inner component 4, which is positioned above the EA part collar 2a. Thus, EA part 2 and door sill inner component 4 are engaged with each other by bolts and nuts. Furthermore, the fastening part between EA part 2 and door sill inner component 4 is door sill inner component fastening part 42.

[0056] then, Figure 6 This diagram illustrates an example of a state where an external force is applied to EA part 2 due to a collision, etc. Here, there is a gap in the Z-direction height between the door sill inner component fastener 42 and EA part 2. Therefore, as... Figure 6As shown by the arrow, when an external force is applied from the front end in the X direction, EA part 2 is crushed while rotating counterclockwise.

[0057] By rotating EA 2 counterclockwise, a downward force is applied to the fastening part 41 of the fastener that secures EA 2 and the fastener 3 together. At this time, the downward force is applied to the spot welds 3b and 3c that join the fastener 3 and the lower housing 12. In particular, the spot weld 3c that joins the fastener 3 and the lower housing flange 12b is subjected to a greater downward force than the spot weld 3b that joins the fastener 3 and the lower housing body 12a. In this case, at the lower housing flange 12b, the front end deforms by being pulled downward.

[0058] Here, the steel plate of the upper housing flange 11b is thin and easily deformed. Therefore, the upper housing flange 11b easily follows the downward deformation of the lower housing flange 12b. As a result, it is possible to prevent the adhesive 15 from peeling off from the upper housing flange 11b and the lower housing flange 12b in the gap 14.

[0059] In addition, the front ends of the upper housing flange 11b and the lower housing flange 12b, which are provided with fastening parts 23, can be bent downwards in advance.

[0060] This allows for a longer distance between the front end of the flange 22 and the EA sleeve 2a. In other words, in the battery pack 1, when the EA sleeve 2a moves close to the flange 22 due to an external force, the distance at which it can move without colliding with the flange 22 can be further increased.

[0061] Based on the foregoing disclosure, it should be understood that the embodiments of this disclosure can be modified in various ways. Such modifications should not be considered as departing from the spirit and scope of this disclosure, and all modifications that can be reasonably inferred by those skilled in the art based on common technical knowledge are within the protection scope of the appended claims.

Claims

1. A battery pack, wherein the battery pack is provided with: an upper case having an upper case main body portion and an upper case flange provided at an end portion of the upper case main body portion; and a lower case disposed below the upper case and having a lower case main body portion and a lower case flange provided at an end portion of the lower case main body portion, a bending load at which the upper case flange starts to deform is weaker than a peeling strength at which an adhesive inserted into a gap between the upper case flange and the lower case flange starts to peel off when the upper case flange and the lower case flange are fixed.

2. The battery pack according to claim 1, wherein the upper case flange is provided with: a first flange portion provided at an end portion side of the upper case flange and configured to be closer to the lower case flange; a second flange portion provided at the upper case main body portion side compared to the first flange portion and configured to be farther from the lower case flange than the first flange portion is from the lower case flange; and a bent portion formed between the first flange portion and the second flange portion.

3. The battery pack according to claim 2, wherein the upper case is formed using a steel sheet, the lower case is formed using a steel sheet, the steel sheet used for the upper case is thinner than the steel sheet used for the lower case.

4. The battery pack according to claim 3, wherein the adhesive is polyurethane, a peeling load value of the adhesive is at least twice or more than the bending load value of the upper case.

5. The battery pack according to claim 4, wherein a front end of the upper case flange and a front end of the lower case flange are respectively bent downward in advance. ​

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