JP7002271B2 - Battery pack - Google Patents

Description

The present invention relates to a battery core pack having a plurality of battery cells held in a cell holder, and a battery pack including a case for accommodating the battery core pack.

For example, as described in Patent Document 1, a battery core pack having a plurality of battery cells held in a cell holder as a battery pack that is detachably mounted on an electric vehicle such as an electrically assisted bicycle or an electric motorcycle. Those provided with a case for accommodating the battery core pack are known.

The case has an outer shell case that covers the side surface of the battery core pack, a bottom case that is attached to the lower end of the outer shell case and covers the bottom surface of the battery core pack, and a top case that covers the upper surface of the battery core pack. The top case is provided with a handle that can be gripped when carrying the battery pack.

Special Table 2016-534518

By the way, in this type of battery pack, it is assumed that the handle provided on the top case is gripped and attached / detached to / from an electric vehicle or the like as described above. Impact load is likely to be applied by colliding with the ground. If this impact load is transmitted from the bottom case to the battery core pack, there is a concern that a load exceeding the withstand load will be applied to the battery cell or the like of the battery core pack.

The present invention has been made to solve the above-mentioned problems, and provides a battery pack having improved durability by suppressing transmission of an impact load from the bottom case to the battery core pack.

In order to achieve the above object, the present invention is a battery pack including a battery core pack having a plurality of battery cells held in a cell holder and a case for accommodating the battery core pack, wherein the case is the same. It has an outer shell case that covers the side surface of the battery core pack and a bottom case that covers the bottom surface of the battery core pack. Inside the outer shell case, a battery core pack frame that supports the battery core pack is fixed. The bottom of the bottom case is provided with a fixing convex portion having a hollow shape protruding toward the battery core pack frame and having a fixing end face portion on the protruding end side, and is provided with the fixing end face portion. The battery core pack frame is characterized in that it is fixed by a fastening member with a countersunk spring interposed between the battery core pack frame.

In this battery pack, since a disc spring is interposed between the battery core pack frame and the fixing end face portion, even if an impact load is applied from the bottom case side due to the battery pack falling or the like, the impact is applied. The load can be absorbed by the disc spring. As a result, it is possible to prevent the above-mentioned impact load from being transmitted from the bottom case to the battery core pack, so that it is possible to prevent a load exceeding the withstand load from being applied to the battery cell or the like of the battery core pack. As a result, the durability of the battery pack can be improved.

In the above battery pack, the fastening member has a bolt, a nut, and a collar including a head and a shaft portion, and the shaft portion includes the battery core pack frame, the disc spring, and the fixing end face portion. The nut is inserted into at least the disc spring and the fixing end face portion along the laminating direction of the laminated portion, and the nut is attached to the tip end side of the shaft portion inside the hollow of the fixing convex portion. Is interposed between the outer peripheral surface of the shaft portion and the disc spring and the fixing end face portion, and the collar and the fixing end face portion can move relatively along the axial direction of the collar. There is.

In this case, the fixing end face portion can move along the axial direction of the collar on the outer peripheral surface side of the collar. Therefore, when an impact load is applied from the bottom case side, the fixing end face portion and the battery core pack frame can be smoothly brought into close contact with each other, and the disc spring can be satisfactorily elastically deformed between them. .. That is, the above impact load can be efficiently absorbed by the disc spring. As a result, it is possible to effectively suppress the transmission of the impact load to the battery core pack and improve the durability of the battery pack.

In the above battery pack, it is preferable that a surface pressure reducing portion is interposed between the fixing end face portion and the disc spring. In this case, when the above impact load is applied, the surface pressure generated between the fixing end face portion and the disc spring can be reduced by the surface pressure reducing portion, so that the bottom of the fixing convex portion or the like can be reduced. It is possible to prevent the case from being damaged. As the surface pressure reducing portion, a washer, a spacer with a flange that can hold the position of the disc spring and can reduce the surface pressure in the same manner as the washer can be used.

In the above battery pack, the fixing protrusions are provided at the four corners of the rectangular bottom of the bottom case, respectively . As a result, the impact load can be absorbed by the disc spring regardless of the direction in which the impact load is applied to the bottom case, so that the durability of the battery pack can be effectively improved. Can be done.

According to the battery pack of the present invention, it is possible to suppress the transmission of the impact load from the bottom case to the battery core pack and improve the durability.

It is a schematic perspective view of the battery pack which concerns on embodiment of this invention. It is a schematic perspective view of a bottom case. It is sectional drawing of the main part of the bottom case, the lower battery core pack frame, and a part of the lower end side of the outer shell case. It is explanatory drawing explaining the disc spring in the state which the impact load is not applied to the bottom case. It is explanatory drawing explaining the disc spring when an impact load is applied to a bottom case. It is an exploded perspective view of a battery core pack.

A preferred embodiment of the battery pack according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic perspective view of the battery pack 10 according to the present embodiment. In FIG. 1, the outer shell case 12 is shown by a two-dot chain line for easy understanding, and the components arranged inside the outer shell case 12 are shown.

The battery pack 10 can be suitably applied as, for example, a portable battery pack 10 that is detachably mounted on an electric vehicle (not shown) such as an electric assist bicycle or an electric motorcycle. Therefore, an example in which the battery pack 10 is mounted on an electric vehicle will be described below, but the present invention is not particularly limited to this, and the battery pack 10 can be applied to various devices requiring electric power. .. Further, the vertical direction of the battery pack 10 is based on the vertical direction (directions of arrows X1 and X2 in FIG. 1) when the battery pack 10 is mounted on the electric vehicle.

As shown in FIG. 1, the battery pack 10 includes a case 14, a connecting body 18 connecting two battery core packs 16a and 16b, a battery management device (Battery Management Unit: BMU) 24, and a connector (not shown). Mainly equipped with a department. The case 14 can be formed of, for example, a metal such as aluminum, a resin (including a fiber reinforced resin), or the like. Further, the case 14 has a bottom case 26 that covers the bottom surface of the connecting body 18, an outer shell case 12 that is attached to the upper end portion of the bottom case 26 and covers the side surface of the connecting body 18, and an upper end portion of the outer shell case 12. It has a top case 28 which is attached to and covers the upper surface of the connecting body 18.

As also shown in FIGS. 2 and 3, the bottom case 26 is a housing having an opening at the upper end portion, and a connector portion or the like is housed therein. The connector portion is exposed to the outside of the case 14 through, for example, a notch 26a (see FIG. 2) formed in the bottom wall of the bottom case 26, and charges the power supply port of the electric vehicle or the connecting body 18. It is possible to connect to the charging device for charging. Both the power supply port and the charging device are not shown. By connecting the connector portion to the power supply port or the charging device, the power supply port or the charging device and the connecting body 18 can be electrically connected via the BMU 24 by a lead wire or the like (not shown).

Fixing protrusions 30 are provided at the four corners of the rectangular bottom of the bottom case 26, respectively. The details of the fixing convex portion 30 will be described later.

As shown in FIGS. 2 and 3, the peripheral wall of the bottom case 26 is provided with a thin-walled portion 26b on the upper end side thereof, and a thick-walled portion 26c is provided on the lower end side of the thin-walled portion 26b. The thickness of the thin portion 26b is smaller than the thickness of the thick portion 26c. Due to these differences in thickness, a stepped surface 26d is formed between the thin portion 26b and the thick portion 26c.

The outer shell case 12 is provided with openings at both ends in the vertical direction. A part of the thin portion 26b of the bottom case 26 on the upper end side is inserted into the opening on the lower end side of the outer shell case 12. That is, the dimension of the thin portion 26b and the dimension of the opening on the lower end side of the outer shell case 12 so that the clearance 27 is formed between the lower end surface of the outer shell case 12 and the stepped surface 26d of the bottom case 26. Is set.

A lower fixing groove 34 is formed along the circumferential direction of the outer shell case 12 on the inner wall of the outer shell case 12 above the upper end of the thin wall portion 26b of the bottom case 26 inserted into the outer shell case 12. There is. A lower battery core pack frame 36 that supports the connecting body 18 from below is fixed to the lower fixing groove 34.

Specifically, as shown in FIGS. 1 and 3, the lower battery core pack frame 36 has a flange portion 40, a contact portion 42, and a connection portion 44. The flange portion 40 extends from the outer peripheral edge portion on the lower end side of the connecting portion 44 toward the outside in the horizontal direction, and is inserted into the lower fixing groove 34. The contact portion 42 has a frame plate shape in which the lower end surface of the connecting body 18 partially contacts. Further, the contact portion 42 is provided with a reinforcing portion 46 so as to cross substantially the center in the horizontal direction, and openings 48 are provided on both sides in a direction orthogonal to the extending direction of the reinforcing portion 46. The outer peripheral edge portion of the abutting portion 42 is arranged at a distance from the inner surface of the outer shell case 12.

The lower end of the connecting portion 44 is connected to the flange portion 40, and the upper end is connected to the abutting portion 42. It is a plate shape that inclines in a direction that increases the distance from the inner surface of the.

As also shown in FIGS. 4 and 5, the fixing convex portion 30 has a hollow shape protruding from the bottom of the bottom case 26 toward the abutting portion 42 of the lower battery core pack frame 36. A fixing end face portion 38 is provided on the protruding end (upper end) side of the fixing convex portion 30. The fixing end face portion 38 and the lower battery core pack frame 36 are fixed by a fastening member 52 with a plurality of laminated disc springs 50 interposed between each other.

A cylindrical portion 39 may be provided on the outer peripheral edge portion of the fixing end surface portion 38 so as to project upward. In this case, by arranging the lower end side of the laminated disc spring 50 inside the tubular portion 39, the positioning of the disc spring 50 and the fixing convex portion 30 can be facilitated.

In the present embodiment, as shown in FIG. 4 and the like, four disc springs 50 stacked in the vertical direction are arranged between the fixing end face portion 38 and the lower battery core pack frame 36. However, the number of disc springs 50 is not particularly limited, and can be appropriately set according to the elastic force, dimensions, and the like of the disc springs 50. A washer 51 (surface pressure reducing portion) is provided between the disc spring 50 arranged at the lower end and the fixing end surface portion 38.

The fastening member 52 has a bolt 54, a nut 56, and a collar 58. The head 60 of the bolt 54 is arranged on the upper surface side of the lower battery core pack frame 36 in the laminated portion 62 in which the fixing end face portion 38, the disc spring 50, and the lower battery core pack frame 36 are laminated. The head 60 of the bolt 54 and the lower battery core pack frame 36 may be joined by welding or the like.

The shaft portion 64 of the bolt 54 includes a through hole 36a provided in the lower battery core pack frame 36 and a through hole 50a provided in the disc spring 50 so as to penetrate the laminated portion 62 along the laminating direction. It is inserted into a through hole 38a provided in the fixing end face portion 38. The nut 56 is attached to the tip end side of the shaft portion 64 at the hollow inner portion 30a of the fixing convex portion 30.

The collar 58 has a cylindrical shape interposed between the outer peripheral surface of the shaft portion 64 and the disc spring 50 and the fixing end surface portion 38. The upper end surface of the collar 58 abuts on the lower surface of the lower battery core pack frame 36. Further, a flange portion 66 is provided at the lower end of the collar 58, and the flange portion 66 is interposed inside the hollow interior 30a of the fixing convex portion 30 between the lower surface of the fixing end face portion 38 and the nut 56.

The collar 58 and the fixing end face portion 38 are relatively movable along the axial direction of the collar 58. That is, the outer diameter of the collar 58 is smaller than the diameter of the through hole 38a of the fixing end face portion 38 and the diameter of the through hole 50a of the disc spring 50.

As shown in FIG. 1, a part of the lower end side of the top case 28 is inserted into the opening on the upper end side of the outer shell case 12. An upper fixing groove 74 is formed on the inner wall of the outer shell case 12 below the lower end of the top case 28 inserted into the outer shell case 12. The upper battery core pack frame 76 that abuts on the upper end surface of the connecting body 18 is fixed to the upper fixing groove 74. The upper battery core pack frame 76 may have substantially the same shape as the lower battery core pack frame 36, and may be fixed to the upper fixing groove 74 in a state where the lower battery core pack frame 36 is turned upside down in the vertical direction. can. The connecting body 18 is sandwiched between the upper battery core pack frame 76 fixed to the outer shell case 12 and the lower battery core pack frame 36 as described above.

The top case 28 is a housing having an opening at the lower end, and a handle 78 that can be gripped when carrying the battery pack 10 is provided on the upper end surface. Further, inside the top case 28, a convex portion protruding toward the upper battery core pack frame 76 is provided, and the convex portion and the upper battery core pack frame 76 are fixed by bolts or the like (neither is possible). Illustrated).

The two battery core packs 16a and 16b constituting the connecting body 18 are configured in substantially the same manner as each other. Therefore, the components corresponding to each other of the two battery core packs 16a and 16b are designated by the same reference numerals and will be described in common. When the two battery core packs 16a and 16b are not distinguished from each other, they are also collectively referred to as the battery core pack 16.

The battery core pack 16 has a plurality of battery cells 80 (see FIG. 6) and a cell holder 82. As shown in FIG. 1, in the present embodiment, the battery core pack 16 is formed between the battery core pack 16 and the connector portion to form a space 83 (see FIGS. 1 and 3) for accommodating wiring and the like (not shown). Has a shape in which a part of the lower end side thereof is cut out.

As shown in FIG. 6, the battery cell 80 has, for example, a cylindrical shape, and positive electrode terminals 84 and negative electrode terminals 86 are provided at both ends in the axial direction, respectively. Preferable types of the battery cell 80 include, but are not limited to, a lithium ion secondary battery, and for example, a secondary battery such as a nickel hydrogen battery or a nickel cadmium battery may be used.

The cell holder 82 is configured by combining a positive electrode side holder 82a and a negative electrode side holder 82b, and has a holding portion 90 for holding a plurality of battery cells 80, a holding plate portion 93 provided with an exposed portion 92, a holding portion 90, and an exposed portion. It has a peripheral wall portion 94 surrounding the portion 92. The positive electrode terminal 84 is exposed from the exposed portion 92 of the positive electrode side holder 82a, and the negative electrode terminal 86 is exposed from the exposed portion 92 of the negative electrode side holder 82b.

In the following, regarding the cell holder 82, the above-mentioned vertical direction (hereinafter, also referred to as X direction), the axial direction of the battery cell 80 (the arrows Y1, Y2 direction in FIG. 1, hereinafter, also referred to as Y direction), and the vertical direction. And the direction orthogonal to both the axial direction (the arrows Z1 and Z2 directions in FIG. 1, hereinafter also referred to as the Z direction) will be described as a reference.

The holding portion 90 has a plurality of insertion holes 96, and holds the battery cell 80 in a state of being inserted into the insertion holes 96, respectively. The insertion hole 96 extends along the Y direction, and exposes the positive electrode terminal 84 or the negative electrode terminal 86 of the battery cell 80 from the openings at both ends in the extending direction. The diameter of the insertion hole 96 is a size corresponding to the outer diameter of the battery cell 80. In the plurality of battery cells 80 held in the holding portion 90, the positive electrode terminals 84 are arranged flush with each other, and the negative electrode terminals 86 are arranged flush with each other. Further, a potting material (not shown) made of an insulating resin or the like may be filled between the peripheral surfaces of the plurality of battery cells 80 held by the holding portion 90.

The holding plate portions 93 are provided on both ends of the holding portion 90 in the Y direction, and through holes are provided as exposed portions 92 at positions corresponding to the openings of the insertion holes 96. The positive electrode terminal 84 and the negative electrode terminal 86 (hereinafter, collectively referred to as electrode terminals) are exposed to the outside of the cell holder 82 via the opening of the insertion hole 96 and the exposed portion 92. Further, a plurality of bus bar plates 100 (see FIG. 1) are attached to the holding plate portion 93 so as to cover each of the exposed portion 92 that exposes the positive electrode terminal 84 and the exposed portion 92 that exposes the negative electrode terminal 86. The pressing plate portion 93 is provided with a ridge portion 102 that is interposed between the bus bar plates 100 and insulates each other.

The two battery core packs 16a and 16b are connected to form a connector 18 so that the negative electrode terminal 86 side of one battery core pack 16a and the positive electrode terminal 84 side of the other battery core pack 16b face each other. Has been done.

The positive electrode terminal 84 side of one battery core pack 16a and the negative electrode terminal 86 side of the other battery core pack 16b, in other words, the side surfaces of the connecting body 18 on both sides in the Y direction face the inner surface side of the outer shell case 12.

As shown in FIG. 1, each of the plurality of bus bar plates 100 connects the positive electrode terminals 84 to each other or the negative electrode terminals 86 to each other in parallel by a predetermined number, and enters the exposed portion 92 to come into contact with the electrode terminals. The protruding portion 104 is provided by, for example, embossing. The bus bar plate 100 is provided with a connection end portion 108 to be inserted into a groove 106 provided on the end surface of the peripheral wall portion 94, respectively. By connecting the connection end portion 108 and the above-mentioned lead wire or the like, a plurality of bus bar plates 100 are connected to the connector portion via the BMU 24 in a state of being connected in series with each other.

It is preferable to interpose a heat dissipation sheet (not shown) between the bus bar plate 100 and the inner surface of the outer shell case 12. In this case, the heat generated in the battery cell 80 can be effectively dissipated through the heat radiating sheet, so that the temperature rise of the connecting body 18 can be suppressed.

The upper end of the positive electrode side holder 82a of the battery core pack 16a in the Y direction (arrow Y2 side in FIG. 1) and the other end side of the negative electrode side holder 82b of the battery core pack 16b in the Y direction (arrow Y1 side in FIG. 1). A protruding wall 110 that protrudes upward is provided at the upper end portion of the above. The upper battery core pack frame 76 abuts on the upper end surface of the protruding wall 110. As a result, a space 112 is formed between the connecting body 18 and the upper battery core pack frame 76, and the BMU 24 is arranged in the space 112 (see FIG. 1).

The BMU 24 has, for example, a control unit that controls charging and discharging of the battery core pack 16, a communication unit that communicates with an electric vehicle and a charging device, and a state of the battery core pack 16 detected from the temperature, voltage, and the like of the battery cell 80. It has a storage unit for storing (all not shown).

The battery pack 10 according to the present embodiment is basically configured as described above. In the battery pack 10, for example, the battery cell 80 can be charged by grasping the handle portion 78, carrying the battery pack 10 in the vicinity of the charging device, and connecting the connector portion and the charging device. On the other hand, for example, the battery cell 80 can be discharged by mounting the battery pack 10 carried by gripping the handle portion 78 on the electric vehicle and connecting the connector portion and the power supply port.

In the battery pack 10, it is assumed that the handle portion 78 provided on the top case 28 is gripped and carried in a state where the bottom case 26 side is arranged on the lower side in the vertical direction. Therefore, the impact load is likely to be applied by colliding with the ground from the bottom case 26 side due to dropping or the like during attachment / detachment work to the electric vehicle or the like.

In the battery pack 10 according to the present embodiment, as described above, the disc spring 50 is interposed between the lower battery core pack frame 36 and the fixing end face portion 38. Therefore, even if an impact load is applied from the bottom case 26 side due to the battery pack 10 falling or the like, the impact load can be absorbed by the disc spring 50.

Specifically, as shown in FIG. 4, when the above-mentioned impact load is applied from the state where the above-mentioned impact load is not applied, as shown in FIG. 5, the fixing end face portion 38 becomes the lower battery core. Approach the pack frame 36. As a result, the disc spring 50 interposed between the fixing end face portion 38 and the lower battery core pack frame 36 is elastically deformed in the direction of compression. As a result, the above impact load can be absorbed.

At this time, as described above, the collar 58 and the fixing end face portion 38 are relatively movable along the axial direction of the collar 58. Therefore, the fixing end face portion 38 can move on the outer peripheral surface side of the collar 58 along the axial direction of the collar 58. Therefore, when the above impact load is applied, the fixing end face portion 38 and the lower battery core pack frame 36 can be smoothly brought into close contact with each other, and the disc spring 50 can be satisfactorily elastically deformed between them. become. That is, the impact load can be efficiently absorbed by the disc spring 50.

Further, a washer 51 is interposed between the fixing end face portion 38 and the disc spring 50. Therefore, by applying the above impact load, the surface pressure generated between the fixing end surface portion 38 and the disc spring 50 can be reduced by the washer 51. As a result, it is possible to prevent the bottom case 26 such as the fixing convex portion 30 from being damaged.

As described above, by forming a clearance 27 (see FIG. 3) between the lower end surface of the outer shell case 12 and the stepped surface 26d of the bottom case 26, the bottom case 26 is applied when the above impact load is applied. And the outer shell case 12 can be easily brought close to each other. That is, the fixing end face portion 38 of the bottom case 26 and the lower battery core pack frame 36 fixed to the outer shell case 12 can be easily brought close to each other. As a result, the disc spring 50 interposed between the fixing end face portion 38 and the lower battery core pack frame 36 can be elastically deformed satisfactorily in the compression direction, and the above impact load can be effectively absorbed. become. Further, since the clearance 27 is formed as described above, the impact load transmitted from the bottom case 26 to the outer shell case 12 can be reduced, and damage to the bottom case 26, the outer shell case 12, and the like can be suppressed.

Further, as described above, since the fixing convex portions 30 are provided at the four corners of the rectangular bottom of the bottom case 26, when the above impact load is applied to the bottom case 26 from any direction. However, the impact load can be absorbed by the disc spring 50.

From the above, in this battery pack 10, since the impact load can be effectively suppressed from being transmitted from the bottom case 26 to the connecting body 18, it is possible that a load exceeding the withstand load is applied to the battery cell 80 or the like of the connecting body 18. It can be avoided. As a result, it becomes possible to improve the durability of the battery pack 10.

The present invention is not particularly limited to the above-described embodiment, and various modifications can be made without departing from the gist thereof.

For example, in the battery pack 10 according to the above embodiment, the fixing convex portions 30 are provided at the four corners of the rectangular bottom of the bottom case 26, respectively. However, the location and number of the fixing protrusions 30 are not particularly limited. As an example, the fixing convex portion 30 may be provided so as to project toward the reinforcing portion 46 of the lower battery core pack frame 36.

In the above embodiment, the washer 51 is interposed between the fixing end face portion 38 and the disc spring 50, but the present invention is not particularly limited to this. The washer 51 may not be interposed between the fixing end face portion 38 and the disc spring 50. Further, a spacer with a flange (not shown) or the like may be interposed between the fixing end face portion 38 and the disc spring 50 as a surface pressure reducing portion instead of the washer 51. The flanged spacer can hold the disc spring 50 in a positioned state, and can reduce the surface pressure generated between the fixing end face portion 38 and the disc spring 50, similarly to the washer 51. Not limited to the washer 51 and the spacer with a flange, a configuration capable of reducing the surface pressure generated between the fixing end face portion 38 and the disc spring 50 can be interposed.

In the above embodiment, the head 60 of the bolt 54 is arranged on the upper surface side of the lower battery core pack frame 36, and the shaft portion 64 of the bolt 54 is the through hole 36a of the lower battery core pack frame 36 and the dish. It was decided to be inserted into the through hole 50a of the spring 50 and the through hole 38a of the fixing end face portion 38. However, for example, the lower battery core pack frame 36 may not be provided with the through hole 36a, and the head portion 60 may be joined to the lower surface of the lower battery core pack frame 36 by welding or the like. In this case, the shaft portion 64 is inserted into the through hole 50a of the disc spring 50 and the through hole 38a of the fixing end surface portion 38, and the upper end surface of the collar 58 abuts on the head 60.

The battery pack 10 according to the above embodiment includes a connecting body 18 in which two battery core packs 16a and 16b are connected. However, the battery pack 10 may include only one battery core pack, or may include a connector (not shown) in which three or more battery core packs are connected.

In the battery pack 10 according to the above embodiment, the lower battery core pack frame 36 has a flange portion 40, an abutting portion 42, and a connecting portion 44, but the present invention is not particularly limited thereto. The lower battery core pack frame 36 may have a configuration capable of supporting the connecting body 18 (battery core pack 16) inside the outer shell case 12. The same applies to the upper battery core pack frame 76.

10 ... Battery pack 12 ... Outer shell case 14 ... Case 16, 16a, 16b ... Battery core pack 18 ... Connecting body 26 ... Bottom case 28 ... Top case 30 ... Fixing convex part 30a ... Hollow inside 36 ... Lower battery core pack Frame 38 ... Belleville spring 52 ... Fastening member 54 ... Bolt 56 ... Nut 58 ... Collar 60 ... Head 62 ... Laminated part 64 ... Shaft 66 ... Flange 80 ... Battery cell 82 ... Cell holder

Claims (3)

A battery pack including a battery core pack having a plurality of battery cells held in a cell holder and a case for accommodating the battery core pack.
The case has an outer shell case that covers the side surface of the battery core pack and a bottom case that covers the bottom surface of the battery core pack.
A battery core pack frame that supports the battery core pack is fixed inside the outer shell case.
The bottom of the bottom case is provided with a fixing convex portion having a hollow shape protruding toward the battery core pack frame and having a fixing end face portion on the protruding end side.
The fixing end face portion and the battery core pack frame are fixed by a fastening member with a disc spring interposed between them.
The fastening member has a bolt, a nut, and a collar including a head and a shaft portion.
The shaft portion is inserted into at least the disc spring and the fixing end face portion along the stacking direction of the laminated portion of the battery core pack frame, the disc spring, and the fixing end face portion.
The nut is attached to the tip end side of the shaft portion inside the hollow of the fixing convex portion.
The collar is interposed between the outer peripheral surface of the shaft portion and the disc spring and the fixing end surface portion.
A battery pack characterized in that the collar and the fixing end face portion are relatively movable along the axial direction of the collar . A battery pack including a battery core pack having a plurality of battery cells held in a cell holder and a case for accommodating the battery core pack.
The case has an outer shell case that covers the side surface of the battery core pack and a bottom case that covers the bottom surface of the battery core pack.
A battery core pack frame that supports the battery core pack is fixed inside the outer shell case.
The bottom of the bottom case is provided with a fixing convex portion having a hollow shape protruding toward the battery core pack frame and having a fixing end face portion on the protruding end side.
The fixing end face portion and the battery core pack frame are fixed by a fastening member with a disc spring interposed between them.
The battery pack is characterized in that the fixing convex portions are provided at the four corners of the rectangular bottom portion of the bottom case, respectively. In the battery pack according to claim 1 or 2.
A battery pack characterized in that a surface pressure reducing portion is interposed between the fixing end surface portion and the disc spring.

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