Battery pack

Abstract

To provide a battery pack that suppresses the spread of fire in the event of a fire.SOLUTION: A battery pack 20 includes an upper case 22 made of synthetic resin and having an upper case body 23, an upper flange 24 protruding outward from the outer periphery of the upper case body along a horizontal plane, and protrusions 25, 26, 27, 28, 29 protruding upward from at least one of the upper case body and the upper flange, a lower case 42 having a lower case body 43 and a lower flange 44 protruding outward from the outer periphery of the lower case body along the horizontal plane and arranged to face the upper flange from below, and a storage unit 51 arranged in a storage space S1 formed by the upper case body and the lower case body.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] 2. Description of the Related Art Conventionally, battery packs in which a power storage unit is disposed in a case are known (see, for example, Patent Documents 1 and 2).

[0003] The case includes an upper case and a lower case. The upper case has an upper case body formed in a cylindrical shape with a top and an upper flange protruding outward from the outer periphery of the lower end of the upper case body, while the lower case has a lower case body formed in a cylindrical shape with a bottom and a lower flange protruding outward from the outer periphery of the upper end of the lower case body. The upper flange of the upper case is disposed opposite the lower flange of the lower case. The power storage unit stores a predetermined amount of electric power and is disposed within the upper case body and the lower case body. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2014 / 109243 [Patent Document 2] JP 2020-40385 A Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, it has been considered to form the case from a synthetic resin. The battery pack is used in electric vehicles and the like. For example, if an electric vehicle collides with a vehicle that runs on the combustion of gasoline (hereinafter referred to as a gasoline vehicle), a fire may break out due to gasoline leaking from the gasoline vehicle, and the battery pack may burn as a result of this fire. The inventors have studied the fire spread suppression performance in the battery packs of Patent Documents 1 and 2 and have found that there is room for improvement in the fire spread suppression performance.

[0006] The present invention has been made in consideration of the above problems, and has an object to provide a battery pack that suppresses the spread of fire in the event of a fire. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention proposes the following means. (1) Aspect 1 of the present invention is a battery pack comprising an upper case made of synthetic resin, the upper case having an upper case body, an upper flange protruding outward from the outer periphery of the upper case body along a horizontal plane, and a convex portion protruding upward from at least one of the upper case body and the upper flange; a lower case body, and a lower flange protruding outward from the outer periphery of the lower case body along the horizontal plane and positioned so as to face the upper flange from below; and a storage unit positioned in a storage space formed by the upper case body and the lower case body.

[0008] In this aspect of the invention, the upper flange and the lower flange are disposed opposite each other, so that the power storage unit is held in the storage space formed between the upper case body and the lower case body. For example, a flame that occurs below the battery pack spreads from the outside of the upper flange and the lower flange, enveloping the battery pack. The flame spreads upward from at least one of the upper case body and the upper flange, and the flame that burns the protrusion spreads upward at the protrusion. However, no other components of the battery pack are located above the protrusion. Therefore, the flame that burns the upper end of the protrusion cannot spread. Therefore, the spread of fire to the battery pack in the event of a fire can be suppressed.

[0009] (2) A second aspect of the present invention may be a battery pack as described in (1), wherein the upper case body has an upper side wall formed in a cylindrical shape and a top wall covering an opening formed at an upper end of the upper side wall. In this aspect of the invention, the power storage unit can be accommodated in a part of the accommodating space formed in the upper side wall.

[0010] (3) A third aspect of the present invention may be the battery pack according to (2), in which the protrusion includes a first protrusion disposed on an outer periphery of the top wall. As a result of careful consideration, the inventors of this invention found that in the event of a fire, flames often spread upward along the upper side wall. By arranging the first convex portion on the outer periphery of the top wall, i.e., near the upper end of the upper side wall, it is possible to prevent the flames that spread upward along the upper side wall and further along the first convex portion from spreading beyond the first convex portion to the top wall, etc.

[0011] (4) A fourth aspect of the present invention may be the battery pack according to (3), wherein the convex portion includes a second convex portion disposed on the top wall more inward than the first convex portion. In this invention, it is possible to prevent a fire that has spread beyond the first convex portion along the top wall from spreading beyond the second convex portion to the top wall or the like located more inward than the second convex portion.

[0012] (5) A fifth aspect of the present invention may be the battery pack according to (3) or (4), in which the first protrusion is disposed around the entire outer periphery of the top wall. In this invention, the spread of flames that have spread upward along the upper side wall beyond the first convex portion to the top wall, etc. can be suppressed over the entire outer periphery of the top wall.

[0013] (6) A sixth aspect of the present invention may be the battery pack described in (4), in which the first protrusions are arranged in a plurality of spaces apart from each other along the outer circumferential edge of the top wall, and the inside of a gap formed between a pair of adjacent first protrusions along the outer circumferential edge of the top wall is blocked by the second protrusions. In this invention, the spread of fire that spreads inward along the top wall through the gap formed between the pair of first protrusions can be suppressed by the second protrusions.

[0014] (7) A seventh aspect of the present invention may be the battery pack according to any one of (1) to (6), in which the protrusion includes a flange protrusion disposed on an outer circumferential edge of the upper flange. In this invention, the flame that wraps around from the outside of the upper flange and burns the outer end of the upper flange can be prevented from spreading beyond the flange convex portion and toward the inside of the upper flange. Effect of the Invention

[0015] In the battery pack of the present invention, the spread of fire can be suppressed in the event of a fire. [Brief description of the drawings]

[0016] [Figure 1] 1 is a cross-sectional side view of a main portion of an electric vehicle in which a battery pack according to an embodiment of the present invention is used. [Diagram 2] FIG. 2 is a plan view of the battery pack. [Diagram 3]FIG. 11 is a cross-sectional side view illustrating a state in which an experiment was conducted to burn the battery pack. [Figure 4] FIG. 2 is a plan view of a battery pack according to a first modified example of an embodiment of the present invention. [Diagram 5] FIG. 11 is a cross-sectional side view of a battery pack according to a second modified example of one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an electric vehicle using an embodiment of a battery pack according to the present invention will be described with reference to FIGS. 1 to 5. FIG. As shown in FIG. 1, the electric vehicle 1 includes a chassis 10, tires 15, and a battery pack 20 of the present embodiment. For example, the chassis 10 of this embodiment constitutes a part of the framework of the electric vehicle 1. The chassis 10 extends along a horizontal plane. Here, "A is along B" means that the angle between A and B is 30 degrees or less. It is more preferable that this angle is 15 degrees or less. For example, A corresponds to the chassis 10, and B corresponds to the horizontal plane. The chassis 10 supports a motor (not shown). An opening 10a that penetrates in the vertical direction is formed in the chassis 10. A plurality of through holes (reference numbers omitted) that penetrate in the vertical direction are formed on the periphery of the opening 10a in the chassis 10.

[0018] The battery pack 20 is supported by the chassis 10. Electric power is stored in the battery pack 20. The battery pack 20 supplies the stored electric power to the motor based on an instruction from an operator of the electric vehicle 1. The battery pack 20 will be described in detail later. The tire 15 is rotatably supported by the chassis 10 via a suspension (not shown). The motor rotates the tire 15 in a predetermined direction.

[0019] 1 and 2, the battery pack 20 includes a case 21, a power storage unit 51, and a fixing unit 56. The case 21 has an upper case 22 and a lower case . The upper case 22 has an upper case main body 23, an upper flange 24, a first convex portion 25, a second convex portion 26, a third convex portion 27, a fourth convex portion 28, and a flange convex portion 29. The first convex portion 25, the second convex portion 26, the third convex portion 27, the fourth convex portion 28, and the flange convex portion 29 each correspond to a convex portion. The upper case body 23 is formed in a cylindrical shape with a top. That is, the upper case body 23 has an upper side wall 32 and a top wall 33. The upper side wall 32 is formed in a square tube shape (cylindrical shape) with a rectangular edge when viewed in the vertical direction. In the following, a direction along one outer edge (short side) of the upper side wall 32 when viewed in the vertical direction is referred to as a first direction X. The first direction X is a direction along a horizontal plane. In the following, a direction perpendicular to the vertical direction and perpendicular to the first direction X is referred to as a second direction Y.

[0020] The shape of the upper side wall 32 is not limited to this, and may be formed into a cylindrical shape with a triangular edge, a pentagon or more sided edge, or a circular edge when viewed from above and below. The top wall 33 closes an opening formed at the upper end of the upper side wall 32. Hereinafter, the central axis of the top wall 33 will be referred to as the axis O1. For example, the axis O1 passes through the center of gravity of the top wall 33 and extends in the up-down direction.

[0021] The upper flange 24 protrudes along a horizontal plane from the outer circumferential edge of the lower end of the upper sidewall 32 of the upper case body 23 toward the outside of the upper sidewall 32. The term "outside" as used here refers to the direction away from the axis O1. The upper flange 24 protrudes over the entire circumference of the upper sidewall 32. Note that the upper flange 24 may protrude only partly in the circumferential direction of the upper sidewall 32 (partly around the axis O1). A plurality of through holes (reference numbers omitted) penetrating in the up-down direction are formed in the upper flange 24. The plurality of through holes are arranged around the upper side wall 32 at intervals. The first convex portion 25, the second convex portion 26, the third convex portion 27, and the fourth convex portion 28 are formed in the shape of a rib protruding upward from the top wall 33 of the upper case body 23. In this example, the first convex portion 25, the second convex portion 26, the third convex portion 27, and the fourth convex portion 28 have the same protruding length (height). For example, the height of the first convex portion 25 is about 1 to 2 mm. The first convex portion 25, the second convex portion 26, the third convex portion 27, and the fourth convex portion 28 each have a rectangular outer peripheral edge shape when viewed from above.

[0022] The first protrusion 25 is disposed on the outer periphery of the top wall 33. The first protrusion 25 is disposed around the entire outer periphery of the top wall 33. That is, as shown in FIG. 1, a pair of first walls 25a of the first protrusion 25 extend along the first direction X. The pair of first walls 25a are disposed at an interval from each other in the second direction Y. The pair of second walls 25b of the first protrusion 25 extend along the second direction Y and are connected to both ends of the pair of first walls 25a in the first direction X. The first protrusion 25 may be disposed on only a portion of the outer periphery of the top wall 33. The second convex portion 26 is disposed on the inner side (toward the axis O1) of the first convex portion 25 on the top wall 33. The third convex portion 27 is disposed on the inner side of the second convex portion 26 on the top wall 33. The fourth convex portion 28 is disposed on the inner side of the third convex portion 27 on the top wall 33. The second convex portion 26, the third convex portion 27, and the fourth convex portion 28 have a pair of first walls and a pair of second walls (symbols omitted) configured in the same manner as the pair of first walls 25a and the pair of second walls 25b of the first convex portion 25.

[0023] As shown in FIG. 2, the upper case 22 further has two connecting protrusions 36 and two connecting protrusions 37 provided on the top wall 33. The connecting protrusions 36 and 37 each protrude upward from the top wall 33 . The two connecting protrusions 36 extend diagonally across the top wall 33 in a plan view. That is, each connecting protrusion 36 extends from one corner to the other corner of the second protrusion 26. The two connecting protrusions 36 are X-shaped in the plan view of FIG. The two connecting protrusions 37 extend in the first direction X. The two connecting protrusions 37 are disposed in the second direction Y with a gap between them. These connecting protrusions 36 and 37 do not connect the first protrusion 25 and the second protrusion 26 together.

[0024] 1 and 2, the flange protrusion 29 protrudes upward from the upper flange 24. The flange protrusion 29 is disposed on the outer circumferential edge of the upper flange 24. The height of the flange protrusion 29 is approximately the same as the height of the first protrusion 25. When viewed from above, the flange protrusion 29 has a rectangular outer circumferential edge shape.

[0025] The upper case 22 has an upper case body 23, an upper flange 24, a first protrusion 25, a second protrusion 26, a third protrusion 27, a fourth protrusion 28, and a flange protrusion 29 which are integrally formed from synthetic resin.

[0026] Examples of resins used in the synthetic resin include thermoplastic resins, thermosetting resins, and elastomer resins. Examples of thermoplastic resins include polyolefin resins such as polypropylene resin, polyethylene resin, poly(1-)butene resin, and polypentene resin, polyester resins such as polyethylene terephthalate, polystyrene resin, acrylonitrile-butadiene-styrene (ABS) resin, polyvinyl acetal resin, ethylene vinyl acetate copolymer (EVA) resin, polyvinyl alcohol resin, polycarbonate resin, polyphenylene ether resin, acrylic resin, polyamide resin, polyvinyl chloride resin (PVC), novolac resin, polyurethane resin, and polyisobutylene. Examples of thermosetting resins include epoxy resin, vinyl ester resin, urethane resin, phenol resin, urea resin, melamine resin, unsaturated polyester resin, and polyimide. Examples of elastomer resins include acrylonitrile butadiene rubber, ethylene-propylene-diene rubber (EPDM), ethylene-propylene rubber, natural rubber, polybutadiene rubber, polyisoprene rubber, styrene-butadiene block copolymers, hydrogenated styrene-butadiene block copolymers, hydrogenated styrene-butadiene-styrene block copolymers, hydrogenated styrene-isoprene block copolymers, and hydrogenated styrene-isoprene-styrene block copolymers.

[0027] The synthetic resin from which the upper case 22 is made can be, for example, a composition obtained by imparting flame retardancy to the above-mentioned resin. In addition, the upper case 22 may be a resin fiber composite material (fiber reinforced material) in which fibers are mixed with a synthetic resin. For example, a composition in which a synthetic resin contains fibers such as glass fibers or carbon fibers may be used, or fibers such as glass fibers or carbon fibers may be impregnated with a synthetic resin.

[0028] As shown in FIG. 2, the lower case 42 has a lower case body 43 and a lower flange 44. The lower case body 43 is formed in a cylindrical shape with a bottom. That is, the lower case body 43 has a lower side wall 47 and a bottom wall . The lower side wall 47 is formed in a square cylindrical shape having a rectangular edge when viewed in the vertical direction, similar to the upper side wall 32. The bottom wall 48 closes an opening formed in the lower end portion of the lower side wall 47.

[0029] The lower flange 44 protrudes outward along a horizontal plane from the outer peripheral edge of the lower side wall 47 of the lower case body 43. The lower flange 44 is disposed so as to face the upper flange 24 from below the upper flange 24. "A facing B" as referred to here does not only mean that A and B face each other with a gap between them, but also means that A and B come into contact with each other. A plurality of through holes (reference numbers omitted) penetrating in the up-down direction are formed in the lower flange 44. The plurality of through holes are arranged around the lower side wall 47 at intervals.

[0030] The lower case 42 has a lower case body 43 and a lower flange 44 which are integrally formed from the same synthetic resin material as that forming the upper case 22 . The lower case 42 may be made of iron, aluminum, or the like. It is preferable that a sealing member made of rubber or the like is disposed between the upper flange 24 and the lower flange 44 .

[0031] The power storage unit 51 is a known secondary battery. The power storage unit 51 stores a predetermined amount of power and supplies the power to the outside. For example, the power storage unit 51 is a lithium ion battery. The power storage unit 51 is disposed in an accommodation space S1 defined by the upper case body 23 and the lower case body 43. By arranging the upper flange 24 and the lower flange 44 so as to face each other, the electricity storage unit 51 is held in the accommodation space S1 formed between the upper case body 23 and the lower case body 43.

[0032] For example, the fixing portion 56 includes a plurality of bolts 57 and a plurality of nuts 58 . The head of bolt 57 contacts upper flange 24 of upper case 22 from above upper flange 24. The shaft of bolt 57 passes through the through hole of upper case 22, the through hole of lower case 42, and the through hole of chassis 10, respectively. The nut 58 contacts the lower flange 44 of the lower case 42 from below the lower flange 44. The nut 58 fits onto the shaft of the bolt 57. The head of the bolt 57 and the nut 58 sandwich the flanges 24, 44 and the chassis 10 in the vertical direction.

[0033] Next, a state in which an experiment was conducted in which the battery pack 20 configured as above was burned will be described. The experiment was carried out using the battery pack 20 alone. 3, a flame source 100 is disposed below the battery pack 20. For example, the flame source 100 is a tray containing gasoline. In the battery pack 20 of this embodiment, the flame 101 generated from the flame source 100 spreads from the outside of the upper flange 24 and the lower flange 44 so as to envelop the battery pack 20. For example, the flame 101 spreads upward from the upper case body 23 and the upper flange 24, and burns the first protrusion 25 and the flange protrusion 29, and then spreads upward in the first protrusion 25 and the flange protrusion 29. However, no other members of the battery pack 20 are disposed above the first protrusion 25 and the flange protrusion 29. For this reason, the flame 101 that has burned the upper ends of the first protrusion 25 and the flange protrusion 29 cannot spread. Therefore, in the event of a fire, the spread of fire to the battery pack 20 can be suppressed.

[0034] Upper case body 23 has an upper side wall 32 and a top wall 33. Therefore, the power storage unit 51 can be accommodated in a part of accommodating space S1 formed within upper side wall 32. The battery pack 20 has a first protrusion 25 as a protrusion. As a result of intensive research, the inventors have found that in the event of a fire, flame 101 often spreads upward along the upper side wall 32. By arranging the first protrusion 25 on the outer periphery of the top wall 33, i.e., in the vicinity of the upper end of the upper side wall 32, it is possible to prevent the flame 101, which spreads upward along the upper side wall 32 and further along the first protrusion 25, from spreading beyond the first protrusion 25 to the top wall 33, etc.

[0035] The battery pack 20 has the second protrusion 26 as a protrusion. Therefore, it is possible to prevent the flame 101, which has spread beyond the first protrusion 25 along the top wall 33, from spreading beyond the second protrusion 26 to the top wall 33 and the like located inside the second protrusion 26. The first convex portion 25 is disposed around the entire outer periphery of the top wall 33. For this reason, the flame 101 that spreads upward along the upper side wall 32 can be prevented from spreading beyond the first convex portion 25 to the top wall 33 and the like around the entire outer periphery of the top wall 33.

[0036] The battery pack 20 has a flange protrusion 29 as a protrusion. Therefore, it is possible to prevent the flame 101, which wraps around from the outside of the upper flange 24 and burns the outer end of the upper flange 24, from spreading beyond the flange protrusion 29 toward the inside of the upper flange 24.

[0037] The configuration of the battery pack 20 of this embodiment can be modified in various ways, as described below. 4 has an upper case 67 instead of the upper case 22 in each configuration of the battery pack 20 of the present embodiment. The upper case 67 has a plurality of first protrusions 68 and a plurality of second protrusions 69 instead of the first protrusion 25 and the second protrusion 26 of the upper case 22.

[0038] The multiple first protrusions 68 are arranged so as to be spaced apart from each other along the outer circumferential edge of the top wall 33. Between a pair of adjacent first protrusions 68 along the outer circumferential edge of the top wall 33, a gap S4 is formed. The inner side along the upper surface of the top wall 33 with respect to the gap S4 is blocked by the second convex portion 69. For example, the inner side along the upper surface of the top wall 33 with respect to the gap S4 means the axis O1 side along the upper surface of the top wall 33 with respect to the gap S4. The height of the multiple first protrusions 68 and the height of the multiple second protrusions 69 are approximately the same as the height of the first protrusions 25 .

[0039] In the battery pack 65 of the first modified example configured as described above, the second protrusion 69 can suppress the spread of fire caused by the flame 101 that spreads inward along the top wall 33 through the gap S4 formed between a pair of first protrusions 68. Note that the battery pack 65 of the first modified example may have a second protrusion 26 instead of the multiple second protrusions 69. In this case, the height of the inner portion of the second protrusion 26 along the upper surface of the top wall 33 relative to the first protrusion 68 may be lower than the height of the inner portion of the second protrusion 26 along the upper surface of the top wall 33 relative to the gap S4.

[0040] A battery pack 75 of a second modified example shown in FIG. 5 has an upper case 77 instead of the upper case 22 in each configuration of the battery pack 20 of this embodiment. The upper case 77 has an upper case body 78 instead of the upper case body 23 in each configuration of the upper case 22 . Upper case body 78 is formed in a flat plate shape. No storage space is formed in upper case 77, and storage space S7 in which power storage unit 51 is disposed is formed only in lower case 42. The battery pack 75 of the second modified example can also achieve the same effects as the battery pack 20 of the present embodiment.

[0041] Although one embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and the present invention also includes modifications, combinations, deletions, etc. of the configuration within the scope of the gist of the present invention. Furthermore, it goes without saying that the modified configurations shown in this embodiment can be used in appropriate combinations. For example, in the above-described embodiments, upper case 22, 67, 77 may have at least one of protrusions 25, 26, 27, 28, 29, 68, 69, and may not have the others. The number of protrusions that upper case 22, 67, 77 has is not limited as long as it is one or more. [Explanation of symbols]

[0042] 20,65,75 Battery Pack 22,67,77 Upper case 23,78 Upper case body 24 Upper flange 25,68 First convex part (convex part) 26,69 Second convex part (convex part) 27 Third convex part (convex part) 28 4th convex part (convex part) 29 Flange convex part (convex part) 32 Upper side wall 33 Ceiling Wall 42 Lower case 43 Lower case body 44 Lower flange 51 Power storage unit S1, S7 Storage Space

Claims

1. an upper case made of synthetic resin, the upper case having an upper case body, an upper flange protruding outward along a horizontal plane from an outer periphery of the upper case body, and a convex portion protruding upward from at least one of the upper case body and the upper flange; a lower case including a lower case body and a lower flange that protrudes outward from an outer periphery of the lower case body along a horizontal plane and is disposed so as to face the upper flange from below; a power storage unit disposed in an accommodation space defined by the upper case body and the lower case body; A battery pack comprising:

2. The upper case body includes: A cylindrically formed upper side wall; a top wall that closes an opening formed at an upper end of the upper side wall; 10. The battery pack of claim 1, comprising:

3. The battery pack according to claim 2 , wherein the protrusion includes a first protrusion disposed on an outer circumferential edge of the top wall.

4. The battery pack according to claim 3 , wherein the convex portion includes a second convex portion disposed on the top wall more inward than the first convex portion.

5. The battery pack according to claim 3 , wherein the first protrusion is disposed around an entire outer periphery of the top wall.

6. The first protrusions are arranged in a plurality of portions spaced apart from each other along the outer circumferential edge of the top wall, 5. The battery pack according to claim 4, wherein an inner side along an upper surface of the top wall, with respect to a gap formed between a pair of the first protrusions adjacent to each other along the outer circumferential edge of the top wall, is blocked by the second protrusion.

7. The battery pack according to claim 1 , wherein the protrusion comprises a flange protrusion disposed on an outer circumferential edge of the upper flange.

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