Battery pack

Abstract

To provide a battery pack that suppresses water ingress into the pack. [Solution] The battery pack 1 comprises an upper case 11 having an upper case body 11a and an upper case flange 11b provided at the end of the upper case body 11a, a lower case 12 having a lower case body 12a and a lower case flange 12b provided at the end of the lower case body 12a, and a lower case 12 disposed below the upper case 11, wherein the bending load at which the upper case flange 11b begins to deform is weaker than the peel strength at which the adhesive inserted into the gap 14 between the upper case flange 11b and the lower case flange 12b begins to peel off when fixing the upper case flange 11b and the lower case flange 12b.

Description

Technical Field

[0001] The present disclosure relates to a battery pack.

Background Art

[0002] In recent years, a battery pack in which a battery module combining a plurality of battery cells is stored in a case has been used. This case is formed by fastening a lower case and an upper case.

[0003] Patent Document 1 describes that a convex portion protruding toward the lower case side is provided on the flange of the upper case, and a sealing material made of a urethane resin adhesive is filled in the gap between the flange of the upper case and the flange of the lower case.

[0004] At this time, the sealing material is filled inside the battery case rather than the convex portion provided on the upper case, and adheres to each flange of the upper case and the lower case. Then, the gap between the flanges of the upper case and the lower case is sealed by the sealing material curing in a state of being adhered to each flange.

Prior Art Documents

Patent Documents

[0005] [[ID=�1]]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the battery case disclosed in Patent Document 1, the flanges provided on the upper and lower cases have high rigidity, meaning that flange deformation is not anticipated. Therefore, if an external force such as a collision occurs, it is conceivable that the adhesive will peel off in the gap between each flange, causing the bonded portion to break. In this case, in a battery pack, if there is moisture outside the pack, there is a risk of water seeping into the inside of the pack where the battery module and other equipment are located.

[0007] This disclosure provides a battery pack that suppresses water ingress into the pack. [Means for solving the problem]

[0008] The battery pack according to this disclosure comprises an upper case body, an upper case having an upper case flange provided at the end of the upper case body, a lower case body, and a lower case having a lower case flange provided at the end of the lower case body, and disposed below the upper case, wherein the bending load of the upper case flange is weaker than the peeling load of the adhesive inserted into the gap between the upper case flange and the lower case flange when fixing the upper case flange and the lower case flange. This prevents the flange itself from deforming and the bonded portion from breaking when an external force is applied, without the adhesive peeling off. [Effects of the Invention]

[0009] This disclosure makes it possible to provide a battery pack that suppresses water ingress into the pack. [Brief explanation of the drawing]

[0010] [Figure 1] This is a side view showing an example of the configuration of a battery pack according to Embodiment 1. [Figure 2] This is an enlarged side view of the flange portion according to Embodiment 1, showing the state in which an external force is applied. [Figure 3]This is a side view showing the upper case flange according to Embodiment 1 with a bent portion provided. [Figure 4] This is a side view of the battery pack with the EA material and reinforcement attached according to Embodiment 1. [Figure 5] This is a perspective view of the reinforcement according to Embodiment 1. [Figure 6] This is a side view of the battery pack in which an external force is applied to the EA material according to Embodiment 1. [Modes for carrying out the invention]

[0011] Embodiment 1 The battery pack according to this embodiment will be described below with reference to the drawings. Figure 1 is a schematic diagram showing an example of the configuration of the battery pack 1.

[0012] As shown in Figure 1, the battery pack 1 comprises an upper case 11 and a lower case 12. Here, as shown in Figure 1, the battery pack 1 is long in the X direction, and the upper case flange 11b and lower case flange 12b, which will be described later, are provided at the ends in the X direction. Furthermore, the upper case 11 is positioned on the upper side in the Z direction, and the lower case 12 is positioned on the lower side in the Z direction and joined together. Note that the X, Y, and Z directions are mutually orthogonal directions.

[0013] The upper case 11 comprises an upper case body portion 11a and an upper case flange 11b. The upper case flange 11b is formed at both ends of the upper case body portion 11a in the X direction.

[0014] The lower case 12 comprises a lower case body 12a and a lower case flange 12b. The lower case flange 12b is formed at both ends of the lower case body 12a in the X direction.

[0015] The upper case main body portion 11a is arranged to face the lower case main body portion 12a in the Z direction. Hereinafter, the upper case main body portion 11a and the lower case main body portion 12a are collectively referred to as the main body portion 21.

[0016] The upper case flange 11b is arranged to face the lower case flange 12b in the Z direction. Hereinafter, the upper case flange 11b and the lower case flange 12b are collectively referred to as the flange portion 22, and it is assumed that the flange portion 22 is provided at both ends of the main body portion 21 in the X direction. Also, in the X direction, the location where the vicinity of the tip of the upper case flange 11b and the vicinity of the tip of the lower case flange 12b are fastened is referred to as the fastening portion 23.

[0017] Furthermore, hereinafter, the space formed between the upper case main body portion 11a and the lower case main body portion 12a is referred to as the storage portion 13, and the space formed between the upper case flange 11b and the lower case flange 12b is referred to as the gap 14. The upper case flange 11b and the lower case flange 12b are joined and sealed with an adhesive 15 within the gap 14.

[0018] Note that the storage portion 13 and the gap 14 are an integral space. Therefore, the battery pack 1 can fasten the upper case flange 11b and the lower case flange 12b with the fastening portion 23 at the X-direction end of the flange portion 22 to prevent displacement, and can seal the storage portion 13 by closing the gap 14 using the adhesive 15.

[0019] The main body portion 21 has a sufficient length in the X direction, Y direction, and Z direction. Therefore, the storage portion 13, which is the space within the main body portion 21, is a space having a sufficient length in the X direction, Y direction, and Z direction, and can store devices such as battery modules and relays. Here, the main body portion 21 is substantially rectangular parallelepiped-shaped extending in the X direction, but an example of a detailed shape will be described later.

[0020] Further, the flange portion 22 is formed shorter than the main body portion 21 in each of the X direction, Y direction, and Z direction. Further, in the flange portion 22, it is formed longer in the X direction than in the Y direction and Z direction.

[0021] Here, the bending rigidity of the upper case flange 11b is made weaker than the peel strength of the adhesive 15. In other words, the bending load at which the upper case flange 11b starts to deform is made weaker than the peel strength at which the adhesive 15 starts to peel. Specifically, in the flange portion 22, the plate thickness forming the upper case flange 11b is sufficiently thinned to reduce the rigidity. Thereby, in the flange portion 22, it is possible to establish that the peel load due to the adhesion of the adhesive 15 > the bending load of the upper case 11.

[0022] In this state, when an external force is applied to the flange portion 22, the upper case flange 11b will follow the deformation of the lower case flange 12b. Therefore, in the flange portion 22, it is possible to suppress excessive force from being applied to the adhesive 15 filled in the gap 14, so that seal peeling of the adhesive 15 can be avoided. Note that the reduction of the rigidity of the upper case 11, the adhesive force of the adhesive 15, and the follow-up of deformation will be described in detail later.

[0023] Note that since the lower case 12 supports the lower parts of the battery module and devices stored in the storage portion 13, it is necessary to have high strength and high rigidity. On the other hand, since the upper case 11 covers the battery module and devices stored in the storage portion 13, the rigidity can be lowered. Therefore, in the upper case 11, it is possible to adopt a configuration in which the rigidities of both the upper case main body portion 11a and the upper case flange 11b are lowered.

[0024] Next, we will describe the specific state when an external force is applied to the flange portion 22. Figures 2(a) and 2(b) are enlarged views of the flange portion 22 showing the state when an external force of several tens of N is applied to the flange portion 22, causing it to deform along with the gap 14 provided inside. Here, Figure 2(a) is a battery pack 1 according to this disclosure in a state where the rigidity of the upper case 11 is reduced, and Figure 2(b) is an example of a related battery pack in a state where the rigidity of the upper case 11 is high. In both cases, adhesive 15 is inserted into the gap 14 inside the flange portion 22, and the adhesive 15 is bonded to the upper case flange 11b and the lower case flange 12b.

[0025] Here, we assume that the flange portion 22 shown in Figures 2(a) and 2(b) is subjected to a large load of several tens of kN due to a collision or the like. Here, the external force is assumed to be applied from the upper case flange 11b side to the lower case flange 12b side, i.e., downward.

[0026] As shown in Figure 2(b), if the upper case flange 11b has a bending rigidity higher than the peel strength of the adhesive 15, the gap 14 widens because the deformation states of the upper case flange 11b and the lower case flange 12b do not match. Therefore, typically the adhesive 15 peels off from either the upper case flange 11b or the lower case flange 12b.

[0027] On the other hand, as shown in Figure 2(a), the upper case flange 11b has a bending stiffness lower than the peel strength of the adhesive 15. Therefore, the upper case flange 11b easily deforms while following the lower case flange 12b. Consequently, the adhesive 15 can maintain its bonded state to the upper case flange 11b and the lower case flange 12b.

[0028] Next, with reference to Figures 3(a) and 3(b), an example in which a bent portion 31 is provided on the upper case flange 11b will be described.

[0029] As shown in Figure 3(a), the upper case flange 11b has a bent portion 31, a first flange portion 32, and a second flange portion 33. Here, the bent portion 31 is positioned between the first flange portion 32 and the second flange portion 33.

[0030] Specifically, the first flange portion 32 is located on the end side of the upper case flange 11b in the X direction, and is positioned so as to be close to the lower case flange 12b. On the other hand, the second flange portion 33 is located on the upper case body portion 11a side in the X direction, compared to the first flange portion 32. Here, the second flange portion 33 is positioned such that the distance between the second flange portion 33 and the lower case flange 12b is longer than the distance between the first flange portion 32 and the lower case flange 12b. Therefore, the upper case flange 11b can be said to be separated into the first flange portion 32 and the second flange portion 33 due to the presence of the bent portion 31.

[0031] In this way, the upper case flange 11b can have a bent portion 31, which is a section with a large radius (R), prepared in advance. This makes the upper case flange 11b more easily deformable when subjected to external forces.

[0032] Furthermore, the location where the adhesive 15 is injected is the gap 14 at the first flange portion 32. That is, in the flange portion 22, in the X direction, the location where the adhesive 15 is inserted to seal the gap 14 is on the outside compared to the bent portion 31. As a result, when an external force is applied to the flange portion 22 of the battery pack 1, the moment length from the main body portion 21 to the adhesive 15 becomes longer, making deformation easier.

[0033] Figure 3(b) is an enlarged view showing, as an example, the state in which an external force is applied to the flange portion 22, which has a bent portion 31 provided on the upper case flange 11b. In Figure 3(b), an example of the state without the bent portion 31 is shown with a solid line, and an example of the state with the bent portion 31 is shown with a dashed line.

[0034] The upper case 11 and lower case 12 are each formed from steel plates. As an example of dimensions, the thickness of the steel plate used for the upper case 11 is approximately t=0.6 mm, and the thickness of the steel plate used for the lower case 12 is approximately t=1.0 mm. Here, the thickness of the upper case 11 is configured to be reliably thinner than the thickness of the lower case 12.

[0035] The adhesive 15 is placed on the first flange portion 32 within the gap 14. For example, if the main body portion 21 is formed with a length of approximately 200 mm in the X direction, the adhesive 15 is applied at a location approximately 15 mm away from the adjacent end of the main body portion 21 in the X direction.

[0036] Here, a urethane adhesive 15 can be used, in which case the peel load is approximately 2.0 N / mm. The deformation load F of the upper case 11 is calculated by solving the equation 150 = F(N) × 15 / (1 / 6 × 1 × 0.6^2), assuming a yield stress of 150 MPa, which gives F = 0.6 N / mm.

[0037] In other words, the peel load required for the adhesive 15 to peel off is 2.0 N / mm, compared to the upper case bending load of 0.6 N / mm required to bend the upper case, meaning the peel load value is higher. For example, the peel load value is set to be at least twice the upper case bending load. Therefore, even if an external force such as a collision is applied to the flange portion 22 with a load of several kN or more, the adhesive 15 will not peel off, and the upper case 11 will follow the deformation of the lower case 12.

[0038] Furthermore, with reference to Figures 4 to 6, an example of a state in which an external force is applied to the battery pack 1 will be explained. Figure 4 shows the state in which an EA (Energy Absolution) material 2, formed from aluminum extrusion or the like, is attached to the battery pack 1. The battery pack 1 and the EA material 2 are connected via a connecting reinforcement 3. In this case, the battery pack 1 is used in a vehicle, and the rocker inner of the vehicle body is bonded to the EA material 2.

[0039] As shown in Figure 4, in this battery pack 1, the lower case flange 12b is provided to be longer than the upper case flange 11b. The upper case flange 11b and the lower case flange 12b are fastened together by a fastening portion 23, and the gap 14 inside the fastening portion 23 is sealed with adhesive 15.

[0040] Figure 5 shows an example of the appearance of the reinforcement 3. The upper part of the reinforcement 3 has a recess 3a that is partially recessed downwards, where fastening components such as nuts can be attached. In addition, the reinforcement 3 has multiple spot points 3b set at the lower end and multiple spot points 3c provided at the upper end in the Z direction.

[0041] Figure 4 shows an example in which the spot point 3b of the reinforcement 3 is joined to the lower part of the lower case body 12a, and the spot point 3c is joined to the lower part of the lower case flange 12b.

[0042] The joining of the EA material 2 and the reinforcement 3 will now be described. The EA material 2 has a shape that extends in the X direction and is joined to the reinforcement 3 at a position close to the main body 21. The EA material 2 is also joined to the reinforcement 3 by fastening components set in the recess 3a of the reinforcement 3, i.e., bolts, nuts, etc. Typically, the joining point between the EA material 2 and the reinforcement 3 is below the lower case flange 12b. The fastening part between the EA material 2 and the reinforcement 3 will be referred to as the reinforcement fastening part 41.

[0043] In other words, a portion of the reinforcement 3 is positioned between the EA material 2 and the lower case flange 12b, and is fastened using bolts that penetrate both the EA material 2 and the reinforcement 3.

[0044] Next, the joining of the EA material 2 and the rocker inner 4 will be described. The EA material 2 and the rocker inner 4 are joined in the X direction, with the rocker inner 4 positioned above the EA material 2, further towards the tip of the flange portion 22.

[0045] As an example, an EA material collar 2a is provided at the X-direction end of the EA material 2, and a long bolt passes through it in the Z-direction, reaching the lower part of the rocker inner 4 located above the EA material collar 2a and fastening it. This results in the EA material 2 and the rocker inner 4 being joined by a bolt and nut. The fastening portion between the EA material 2 and the rocker inner 4 is referred to as the rocker inner fastening portion 42.

[0046] Next, Figure 6 shows an example of a state in which an external force due to collision or the like is applied to the EA material 2. Here, there is a gap in height in the Z direction between the rocker inner fastening portion 42 and the EA material 2. Therefore, as shown by the arrow in Figure 6, when an external force is applied from the tip side in the X direction, the EA material 2 will be crushed while rotating counterclockwise.

[0047] The counterclockwise rotation of the EA material 2 causes a downward force to be applied to the reinforcement fastening portion 41 where the EA material 2 and the reinforcement 3 are fastened together. At the same time, downward forces are applied to the spot points 3b and 3c where the reinforcement 3 and the lower case 12 are joined. In particular, the spot point 3c where the reinforcement 3 and the lower case flange 12b are joined experiences a larger downward force compared to the spot point 3b where the reinforcement 3 and the lower case body 12a are joined. In this case, the lower case flange 12b deforms as if its tip is being pulled downwards.

[0048] Here, the upper case flange 11b is made of thin steel and is easily deformed. Therefore, the upper case flange 11b easily follows the downward deformation of the lower case flange 12b. This prevents the adhesive 15 from peeling off from the upper case flange 11b and the lower case flange 12b in the gap 14.

[0049] Furthermore, the upper case flange 11b and the lower case flange 12b can be pre-bent downwards at the tip where the fastening portion 23 is provided.

[0050] This allows the distance between the tip of the flange portion 22 and the EA material collar 2a to be increased. In other words, in the battery pack 1, when the EA material collar 2a moves closer to the flange portion 22 due to an external force, the distance at which it can operate without colliding with the flange portion 22 can be increased.

[0051] It should be noted that the present invention is not limited to the embodiments described above, and can be modified as appropriate without departing from the spirit of the invention. In other words, the above description has been omitted and simplified as appropriate for the sake of clarity, and those skilled in the art can easily change, add, and modify each element of the embodiments within the scope of the present invention. [Explanation of Symbols]

[0052] 1 Battery pack 2 EA material 2a EA material color 3 Reinforce 3a Recess 3b, 3c Spot hitting point 4 Rockin'na 11 Upper Case 11a Upper case main body 11b Upper case flange 12 lower cases 12a Lower case main body 12b Lower Case Flange 13 Storage Unit 14 gaps 15 Adhesives 21 Main body 22 Flange section 23 Fastening section 31. Bending section 32 First flange section 33 Second flange section 41 Reinforcement fastening section 42. Rocker inner fastening section

Claims

1. An upper case comprising an upper case body and an upper case flange provided at the end of the upper case body, It comprises a lower case body and a lower case having a lower case flange provided at the end of the lower case body, and positioned below the upper case. The bending load at which the upper case flange begins to deform is 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 fixing the upper case flange and the lower case flange together. Battery pack.

2. The aforementioned upper case flange is A first flange portion is provided on the end side of the upper case flange and is arranged so as to shorten the distance from the lower case flange, A second flange portion is provided on the upper case body side compared to the first flange portion, and is arranged such that the distance between it and the lower case flange is longer than the distance between the first flange portion and the lower case flange. The device comprises a first flange portion and a bent portion formed between the second flange portion, The battery pack according to claim 1.

3. The upper case is formed using steel plates. The lower case is formed using steel plates, The steel plate used in the upper case is thinner than the steel plate used in the lower case. The battery pack according to claim 2.

4. The aforementioned adhesive is made of urethane, The peel load value of the adhesive is at least twice the bending load value of the upper case. The battery pack according to claim 3.

5. The tip of the upper case flange and the tip of the lower case flange are each bent downwards in advance. The battery pack according to claim 4.

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