Energy storage apparatus

An energy storage apparatus includes: an outer case having a box-shaped outer case and a lid covering one side of the outer case body in a predetermined direction; and an inner lid disposed on one side of one end portion of the energy storage device on the one side in the predetermined direction. The outer case body includes a pair of first side walls facing each other, and a pair of first fixing portions that are respectively provided on the pair of first side walls and attach the inner lid. The inner lid includes a pair of second fixing portions that are respectively connected with the pair of first fixing portions and are arranged at a predetermined distance from each other. The outer case body and the inner lid are fixed by connecting the pair of first fixing portions and the pair of second fixing portions with each other.

TECHNICAL FIELD

The present invention relates to an energy storage apparatus.

BACKGROUND ART

An energy storage apparatus of Patent Document 1 includes an energy storage device and an outer case that accommodates the energy storage device. The outer case includes a box-shaped outer case body made of resin, and a lid mounted on the outer case body.

When this type of outer case body is injection-molded, the outer case body may be deformed so as to warp inward due to factors such as residual stress generated by pressure during injection molding or uneven volume contraction. When the outer case body is deformed in such a way, it becomes difficult to mount the lid on the outer case body, and thus the assemblability of the outer case deteriorates.

In Patent Document 1, the outer case body includes a pair of side walls facing each other and a partition plate that connects the pair of side walls, and the partition plate supports the side walls so as to suppress deformation of the side walls in forming the outer case body.

PRIOR ART DOCUMENTS

Patent Documents

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

However, in Patent Document 1, the partition plate is provided so as to divide the space inside the outer case body into a plurality of spaces, and the space for accommodating the energy storage device is reduced, so that the volume energy density lowers.

It is a first object of the present invention to provide an energy storage apparatus that prevents or suppresses deformation of an outer case body while ensuring the volume energy density of the energy storage apparatus.

Means for Solving the Problems

An energy storage apparatus according to an aspect of the present invention includes: an energy storage device; an outer case having a box-shaped outer case body that accommodates the energy storage device, and a lid that covers one side of the outer case body in a predetermined direction; and a substantially plate-shaped inner lid disposed on one side of an end of the energy storage device on the one side in the predetermined direction, in which the outer case body includes: a pair of first side walls facing each other; a pair of second side walls that face each other and connect the pair of first side walls to each other; and a pair of first fixing portions that are respectively provided on the pair of first sidewalls and attach the inner lid, the inner lid includes a pair of second fixing portions that are respectively connected with the pair of first fixing portions and are arranged at a predetermined distance from each other, the outer case body and the inner lid are fixed by connecting the pair of first fixing portions and the pair of second fixing portions to each other, and the inner lid and the energy storage device are bonded to each other.

Advantages of the Invention

It is possible with the present invention to prevent or suppress deformation of the outer case body while ensuring the volume energy density of the energy storage apparatus.

MODE FOR CARRYING OUT THE INVENTION

An energy storage apparatus according to an aspect of the present invention includes: an energy storage device; an outer case having a box-shaped outer case body that accommodates the energy storage device, and a lid that covers one side of the outer case body in a predetermined direction; and a substantially plate-shaped inner lid disposed on one side of an end of the energy storage device on the one side in the predetermined direction, in which the outer case body includes: a pair of first side walls facing each other; a pair of second side walls that face each other and connect the pair of first side walls to each other; and a pair of first fixing portions that are respectively provided on the pair of first sidewalls and attach the inner lid, the inner lid includes a pair of second fixing portions that are respectively connected with the pair of first fixing portions and are arranged at a predetermined distance from each other, and the outer case body and the inner lid are fixed by connecting the pair of first fixing portions and the pair of second fixing portions to each other.

According to this configuration, the distance between the pair of first fixing portions is defined by a predetermined distance between the pair of second fixing portions. Therefore, even if the pair of first side walls are deformed during injection molding, it is possible to prevent or suppress deformation of the pair of first side walls of the outer case body by appropriately maintaining the distance between the pair of first side walls. Since the inner lid is disposed on one side of one end of the energy storage device, the volume of the space for accommodating the energy storage devices in the outer case body can be ensured, and the volume energy density of the energy storage device can be ensured.

The outer case body may include a bottom wall having a substantially quadrangular shape and connected to the pair of first side walls and the pair of second side walls, and the pair of first side walls may be walls extending along the array direction of a plurality of the energy storage devices, or walls extending in a direction orthogonal to the array direction.

When the outer case body accommodates a plurality of energy storage devices, the first side walls may be long side surfaces depending on the array direction or the number of the energy storage devices, or the size of a case of the energy storage devices. In a case where the plurality of energy storage devices are arranged along the first side walls, the first side walls are walls extending along a direction in which the plurality of energy storage devices are arranged, and may be long side surfaces. Since the long side surfaces are more likely to be deformed during injection molding than the short side surfaces, it is possible to effectively prevent or suppress deformation of the pair of first side walls of the outer case body by appropriately maintaining the distance between the long side surfaces by the pair of first fixing portions and the pair of second fixing portions. In a case where the plurality of energy storage devices are arranged along the second side walls, the first side walls are walls extending along a direction orthogonal to the array direction of the plurality of energy storage devices, and may be short side surfaces. At this time, since the first fixing portions to be fixed to the inner lid are provided on the first side walls, it is possible to effectively prevent or suppress deformation of the first side walls pressed by the expanded energy storage devices.

The pair of first fixing portions may be respectively disposed at central portions of the pair of first side walls in a direction in which the pair of first side walls extend in a cross section intersecting the predetermined direction.

The central portions of the pair of first side walls are more likely to be deformed during injection molding than end portions connected respectively to the pair of second side walls. Therefore, it is possible to effectively prevent or suppress deformation of the pair of first side walls of the outer case body by appropriately maintaining the distance between the central portions of the pair of first side walls by the pair of first fixing portions and the pair of second fixing portions.

The outer case body may include a pair of extension portions respectively extending from inner surfaces of the pair of first side walls, and the pair of first fixing portions may be respectively provided in the pair of extension portions.

The pair of extension portions may be reinforcing ribs provided on the outer case body.

With this configuration where the pair of extension portions are constituted of reinforcing ribs, it is unnecessary to provide reinforcing ribs separately from the pair of extension portions, and space saving can be realized.

The outer case body and the lid may include a heat-welded joint portion. The pair of first fixing portions provided on the pair of first side walls and the pair of second fixing portions provided on the inner lid may form a fixing portion of the outer case body and the inner lid. In the predetermined direction, a position of the fixing portion on the lid side may be located closer to the energy storage device than the joint portion.

With this configuration where the position of the fixing portion on the lid side is located closer to the energy storage device than the joint portion in the predetermined direction, it is possible to prevent a hot plate used for heat-welding the outer case body and the lid from interfering with the fixed portion.

The inner lid and the energy storage device may be bonded to each other.

With this configuration where the inner lid is bonded to the energy storage device, it is possible to suppress warp deformation of the inner lid, and it is thus possible to appropriately maintain the distance between the pair of first side walls, and to effectively prevent or suppress deformation of the pair of first side walls of the outer case body.

One of the pair of first fixing portions and the pair of second fixing portions have a pin while the other have an insertion hole, and a tip portion of the pin may be heat-caulked with the pin penetrating the insertion hole.

According to this structure, a tip portion of a pin inserted into an insertion hole is heat-caulked, and accordingly the outer case body and the inner lid are coupled to each other. Therefore, the outer case body and the inner lid can be firmly coupled to each other, and the work for coupling is facilitated as compared with a case where the outer case body and the inner lid are coupled using bolts. Even when the outer case is provided with a plurality of combinations of pins and insertion holes, it is possible to heat-caulk the plurality of pins simultaneously or substantially simultaneously. Therefore, it is possible to improve the coupling force between the outer case body and the inner lid, and to efficiently manufacture an energy storage apparatus. The energy storage apparatus having the above structure is an energy storage apparatus with a simple configuration and high reliability.

The pair of second fixing portions having the insertion holes are formed in a peripheral edge of the inner lid, and the pair of first fixing portions having the pins may be formed at positions of the outer case body facing the peripheral edges of the inner lid so as to project toward the inner lid.

With this configuration, the tip of the pin can be heat-caulked from above with the pin of the outer case body penetrating the insertion hole of the inner lid. That is, the work of heat caulking can be easily performed. Accordingly, the accuracy of the work is improved, and as a result, the reliability of the energy storage apparatus is improved.

A plurality of the pins are provided on one of the pair of first fixing portions and the pair of second fixing portions, and the plurality of pins may be disposed at positions that do not have rotational symmetry with respect to the center of the one of the outer case body and the inner lid when viewing the one in plan.

According to this configuration, a plurality of the holes provided on the other of the first fixing portion and the second fixing portion are also disposed at positions that do not have rotational symmetry with respect to the center of the other. Accordingly, the one-to-one relationship between the plurality of pins and the plurality of insertion holes is uniquely determined, so that it is easy to determine the orientation (posture) of the inner lid with respect to the outer case body when the inner lid is disposed on the outer case body. That is, in a case where the shape of the inner lid in plan view is a rotationally symmetric shape such as a regular polygon, it is possible to reduce the possibility that the inner lid is disposed (misplacement) on the outer case body in an erroneous orientation (posture). Therefore, an event such as lowering of the manufacturing efficiency due to misplacement or damage to a member due to misplacement, which may cause lowering of the reliability of the energy storage apparatus, is unlikely to occur.

A plurality of the pins are provided on one of the pair of first fixing portions and the pair of second fixing portions, and the shape in plan view, the size, or the posture of one of the plurality of pins may be different from the shape in plan view, the size, or the posture of one or more other pins.

With this configuration where a combination of one of the plurality of pins and one of the plurality of insertion holes is uniquely determined, it is easy to determine the orientation (posture) of the inner lid with respect to the outer case body when the inner lid is disposed on the outer case body. That is, in a case where the shape of the inner lid in plan view is a rotationally symmetric shape such as a regular polygon, the possibility that the inner lid is disposed (misplacement) in an erroneous orientation (posture) on the outer case body is reduced. Therefore, an event such as lowering of the manufacturing efficiency due to misplacement or damage to a member due to misplacement, which may cause lowering of the reliability of the energy storage apparatus, is unlikely to occur.

The inner lid has a substantially rectangular shape in plan view, and one of the pair of first fixing portions and the pair of second fixing portions may be provided with N (N is a positive odd number) pins.

For example, assume that the shape of the inner lid in plan view is a shape that is recognized as a rectangle as a whole, and that three holes into which the pins of the outer case body are inserted are disposed at the peripheral edge of the inner lid. In this case, the inner lid has rotational symmetry at every 180°, while it is impossible to dispose the three pins on the outer case body so as to have rotational symmetry at every 180°. That is, the arrangement positions of the three pins at the outer case body are positions that do not have rotational symmetry at every 180°. Accordingly, misplacement of the inner lid with respect to the outer case body does not occur.

First Embodiment

[Configuration of Energy Storage Apparatus]

The following description will explain the first embodiment of the present invention with reference to the accompanying drawings. The embodiments and a modification example thereof described below are all comprehensive or specific examples. Numerical values, shapes, materials, components, arrangement positions of components, connection forms, and the like illustrated in the following embodiments and the modification example thereof are merely examples, and are not intended to limit the present invention. Among components in the following embodiments and the modification example thereof, components not described in independent claims are described as arbitrary components. In each figure, dimensions or the like are not strictly shown.

In the following description, the length direction, the width direction, and the height direction of an energy storage apparatus1of the present embodiment may be respectively referred to as the X direction, the Y direction, and the Z direction. Specifically, the alignment direction of the energy storage devices, the facing direction of a long side surface of a case of the energy storage devices, or the thickness direction of the case is defined as the X-direction. The alignment direction of electrode terminals in one energy storage device, or the facing direction of a short side surface of a case of the energy storage devices is defined as the Y direction. The alignment direction of the outer case body and the inner lid in the outer case of the energy storage apparatus, the alignment direction of the energy storage device and the bus bar, or the vertical direction is defined as the Z direction. The X direction, the Y direction, and the Z direction are directions that intersect with each other (orthogonally in the following embodiments and the modification example thereof). These directions indicate directions in the posture of the energy storage apparatus1illustrated in the accompanying drawings, and do not necessarily coincide with a direction in an actual use state.

With reference toFIG. 1, the energy storage apparatus1according to the present embodiment includes a plurality of (eight in the present embodiment) energy storage devices2(illustrated inFIG. 2), and a hollow outer case3that accommodates the plurality of energy storage devices2. The outer case3includes an outer case body10that accommodates the plurality of energy storage devices2, and a lid20that covers one side (upper side inFIG. 1) of the outer case body in the Z direction (predetermined direction). The outer case body10and the lid20of the present embodiment are fixed by heat welding as will be described later.

The energy storage apparatus1is an apparatus that can charge electricity from the outside and discharge electricity to the outside. For example, the energy storage apparatus1is a battery module used for power storage or power supply. Specifically, the energy storage apparatus1is used as, for example, a battery for driving or engine starting of a moving body including a motor vehicle such as an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), or a gasoline car, a motorcycle, a watercraft, a snowmobile, an agricultural machine, a construction machine, and an electric railway vehicle such as a train, a monorail, or a linear motor car, or as a stationary battery to be used for home use or for a generator.

With reference toFIG. 2, the energy storage apparatus1includes a substantially plate-shaped inner lid30provided on one side in the Z direction of an end of the energy storage device2on the one side (upper side inFIG. 2) in the Z direction. The energy storage apparatus1includes a plurality of bus bars40that electrically connect adjacent energy storage devices2to each other, and a bus bar cover50disposed to cover the bus bars40from one side in the Z direction. InFIG. 3, components (e.g., a circuit board) other than the energy storage device2, the inner lid30, the bus bar40, and the bus bar cover50are not shown.

Each energy storage device2of the present embodiment is a nonaqueous electrolyte secondary battery such as a lithium ion secondary battery, and is a prismatic battery. The plurality of energy storage devices2are aligned in the X direction and accommodated in the outer case body10. Each energy storage device2includes a positive electrode terminal2aand a negative electrode terminal2bon an end surface on one side in the Z direction. The shape of the energy storage device2, and the number of the energy storage devices2to be aligned are not limited. The energy storage device2is not limited to a nonaqueous electrolyte secondary battery, and may be a secondary battery other than a nonaqueous electrolyte secondary battery, or may be a capacitor. The energy storage device2may be a primary battery that can use stored electricity without the user having to charge electricity. The energy storage device2may be a battery that uses a solid electrolyte. The shape of the energy storage device2is not limited to a prismatic shape, and may be a cylindrical shape, an oblong cylindrical shape, a polygonal prism shape other than a rectangular parallelepiped shape, or the like.

The outer case body10is a box-shaped member obtained by injection-molding a resin. With reference also toFIG. 3, the outer case body10of the present embodiment includes a bottom wall11, a pair of first side walls12A and12B facing each other, and a pair of second side walls13A and13B that face each other and connect the pair of first side walls12A and12B with each other. The pair of first side walls12A and12B and the pair of second side walls13A and13B form an opening on one side of the outer case body10in the Z direction.

The outer case body10and the lid20of the outer case3are made of an insulating material such as, for example, polycarbonate (PC), polypropylene (PP), polyethylene (PE), polystyrene (PS), polyphenylene sulfide resin (PPS), polyphenylene ether (PPE (including modified PPE)), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyamide resin, polyether ether ketone (PEEK), tetrafluoroethylene-perfluoroalkyl vinyl ether (PFA), polytetrafluoroethylene (PTFE), polybutylene terephthalate (PBT), polyether sulfone (PES), ABS resin, or a composite material thereof. Accordingly, the outer case3prevents the energy storage device2or the like from coming into contact with an external metal member or the like.

The bottom wall11has a substantially quadrangular shape and is disposed on a plane (XY plane) perpendicular to the Z direction. Specifically, the bottom wall11of the present embodiment has a substantially rectangular shape and includes a pair of long sides extending in the X direction and a pair of short sides extending in the Y direction.

The pair of first side walls12A and12B of the present embodiment have a substantially rectangular shape, and are disposed on a plane (XZ plane) perpendicular to the Y direction. That is, the pair of first side walls12A and12B are walls extending along the array direction (X direction) of the energy storage devices2. The pair of first side walls12A and12B are continuous with the long sides of the bottom wall11. That is, the pair of first side walls12A and12B of the present embodiment are long side surfaces of the outer case body10. The outer case body10of the present embodiment includes an extension portion14A extending from the inner surface of the first side wall12A toward the first side wall12B, and an extension portion14B extending from the inner surface of the first side wall12B toward the first side wall12A.

The extension portion14A of the present embodiment is composed of a plurality of ribs15formed integrally with the first side wall12A of the outer case body10. Similarly, the extension portion14B of the present embodiment is composed of a plurality of ribs15that are formed integrally with the first side wall12B of the outer case body10.

Each rib15is a rib for reinforcing the outer case body10. The ribs15respectively project in the Y direction from the inner surfaces of the pair of first side walls12A and12B, and extend in the Z direction. The ribs15are arranged at predetermined intervals from each other in the X direction.

The extension portion14A of the first side wall12A is provided with a first fixing portion16A, and the extension portion14B of the second side wall13B is provided with a first fixing portion16B. The pair of first fixing portions16A and16B are arranged at a predetermined distance L1from each other in the Y direction. The first fixing portion16A of the present embodiment is composed of a plurality of pins projecting from the ribs15provided on the first side wall12A to one side in the Z direction. Specifically, the first fixing portion16A includes two first pins17provided in a central portion A1of the first side wall12A, and two second pins18provided in side portions A2of the first side wall12A in the X direction. Similarly, the first fixing portion16B is composed of a plurality of pins projecting from the ribs15provided on the first side wall12B to one side in the Z direction. The first fixing portion16B includes two first pins17provided in the central portion A1of the first side wall12B, and two second pins18provided in the side portions A2of the first side wall12B in the X direction. The central portion A1of the pair of first side walls12A and12B is a region that is located at the center of three regions when the pair of first side walls12A and12B are equally divided into the three regions in a direction (X direction in the present embodiment) in which each of the pair of first side walls12A and12B extends in a cross section orthogonal to the Z direction. The side portions A2of the pair of first side walls12A and12B are regions that are located beside the central portion A1in a direction (X direction in the present embodiment) in which each of the pair of first side walls12A and12B extends in a cross section orthogonal to the Z direction.

The pair of second side walls13A and13B of the present embodiment have a substantially rectangular shape, and are disposed on a plane (YZ plane) perpendicular to the X direction. The pair of second side walls13A and13B are continuous with the short sides of the bottom wall11. That is, the pair of second side walls13A and13B of the present embodiment are the short side surfaces of the outer case body10.

With reference toFIGS. 2 and 4, the inner lid30has a substantially plate shape and a substantially rectangular shape with an outer shape of a similar figure smaller than the inner shape of the outer case body10, and is bonded to an end on one side of the energy storage device2in the Z direction. The inner lid30of the present embodiment includes a second fixing portion31A mechanically connected to a first fixing portion16A provided on the first side wall12A of the outer case body10, and a second fixing portion31B mechanically connected with a first fixing portion16B provided on the first side wall12B of the outer case body10. The pair of second fixing portions31A and31B are arranged at a predetermined distance L2from each other in the Y direction. As with the outer case3, the inner lid30may be formed of an insulating material such as PC, PP, PE, PS, PPS, PPE (including modified PPE), polyamide resin, PET, PBT, PEEK, PFA, PTFE, PES, ABS resin, or a composite material thereof.

The second fixing portion31A of the present embodiment is composed of a plurality of insertion holes through which the plurality of pins17and18provided on the first side wall12A can be inserted. Specifically, the second fixing portion31A includes two first insertion holes32through which two first pins17of the first side wall12A can be inserted, and two second insertion holes33through which two second pins18of the first side wall12A can be inserted. Similarly, the second fixing portion31B of the present embodiment is composed of a plurality of insertion holes through which the plurality of pins17and18provided on the first side wall12B can be inserted. Specifically, the second fixing portion31B includes two first insertion holes32through which two first pins17of the first side wall12B can be inserted, and two second insertion holes33through which the second pins18of the first side wall12B can be inserted.

The bus bar40is a plate-shaped member made of a conductive material such as metal including copper, copper alloy, aluminum, aluminum alloy, and the like. Each bus bar40electrically connects positive electrode terminals2aof the energy storage devices2adjacent to each other in the X direction with each other, negative electrode terminals2bwith each other, or a positive electrode terminal2aand a negative electrode terminal2bwith each other. The bus bars40are welded and joined to the positive electrode terminals2aor the negative electrode terminals2bof the energy storage devices2.

With reference toFIGS. 2 and 5, the bus bar cover50of the present embodiment includes two third insertion holes51through which two first pins17can be inserted, and two notches52provided at positions corresponding to two second pins18.

With reference toFIG. 6, the first fixing portion16A and the second fixing portion31A are mechanically connected with each other, and the first fixing portion16B and the second fixing portion31B are connected with each other, so that the inner lid30and the bus bar cover50are fixed to the outer case body10. Each first pin17includes an umbrella-shaped head17aat an end on one side (upper side inFIG. 6) in the Z direction, and the inner lid30and the bus bar cover50are sandwiched between an end surface of the head17aof the first pin17on the other side in the Z direction, and an end surface of a rib15on the one side in the Z direction.

Similarly, each second pin18includes an umbrella-shaped head18aat an end on one side in the Z direction, and the inner lid30is sandwiched between an end surface of the head18aof the second pin18on the other side in the Z direction, and an end surface of a rib15on the one side in the Z direction. Each notch52of the bus bar cover50is configured so that a head18aof a second pin18and the bus bar cover50do not interfere with each other.

In other words, the first fixing portion16A provided on the outer case body10and the second fixing portion31A provided on the inner lid30, and the first fixing portion16B provided on the outer case body10and the second fixing portion31B provided on the inner lid30form a fixing portion60of the outer case body10and the inner lid30.

As described above, a peripheral edge of the opening of the outer case body10, and a peripheral edge of the lid20are heat-welded. Specifically, the energy storage apparatus1of the present embodiment includes a joint portion70in which the outer case body10and the lid20are heat-welded in the cross section illustrated inFIG. 6. In the Z direction, the position of the fixing portion60on the lid20side (position of an end portion of the head17aof the first pin17on the one side in the Z direction in the present embodiment) Z1is located closer to the energy storage device2than the position of the joint portion70on the energy storage device2side (position of an end portion of the joint portion70on the other side in the Z direction in this embodiment) Z2.

The following description will explain a method of manufacturing the energy storage apparatus1according to the present embodiment.

First, the energy storage device2is disposed inside the outer case body10. Next, the inner lid30having an adhesive applied to a surface to be put into contact with the energy storage device2is prepared, and the first pins17and the second pins18provided on the outer case body10are respectively disposed through the first insertion holes32and the second insertion holes33of the inner lid30.

In this state, an end portion of each second pin18on the one side in the Z direction is heated and pressed to form a head18aof a second pin18and fix the inner lid30to the outer case body10. Generally, this construction method is called “heat caulking”, and, in the present invention, the same construction method is used not only to form the heads18aof the second pins18but also to form the heads17aof the first pins17to be described later. The fixing method of the present invention is not limited only to heat caulking, and, for example, a heat welding method of melting and joining both the heads18aof the second pins18and the inner lid30that are to be joined can be also used. The head18aof each second pin18can be irradiated with a laser to form the head18alike heat caulking, or a portion of the head18aof each second pin18and a portion of the inner lid30which are in contact with each other can be melted and integrated.

Then, the bus bar40is disposed on the positive electrode terminal2aor the negative electrode terminal2bof the energy storage device2, and the bus bar40is welded to the positive electrode terminal2aor the negative electrode terminal2bof the energy storage device2.

Furthermore, the bus bar cover50is disposed so as to cover the bus bar40from one side in the Z direction by passing the first pins17provided on the outer case body10through the third insertion holes51provided at the bus bar cover50. In this state, an end portion of each first pin17on the one side in the Z direction is heated and pressed to form the head17aof the first pin17, and the inner lid30and the bus bar cover50are fixed to the outer case body10.

Finally, as illustrated inFIG. 7, an attachment portion20aof the lid20on the other side in the Z direction, and an end portion10aof the outer case body10on the one side in the Z direction are heat-welded using a hot plate80. An attachment portion20aof the lid20, and an end portion10aof the outer case body10are melted using a hot plate80, and the melted parts are held in a state of being abutted with each other and cooled while being pressed, so that the lid20and the outer case body10are fixed to each other.

According to this configuration, since the first fixing portion16A and the second fixing portion31A are connected with each other and the first fixing portion16B and the second fixing portion31B are connected with each other, a distance L1between the pair of first fixing portions16A and16B is defined by a predetermined distance L2between the pair of second fixing portions31A and31B. Therefore, even if the pair of first side walls12A and12B are deformed during injection molding, it is possible to prevent or suppress deformation of the pair of first side walls12A and12B of the outer case body10by appropriately maintaining the distance between the pair of first side walls12A and12B. Since the inner lid30is disposed on one side of an end of the energy storage device2on the one side, the volume of the space for accommodating the energy storage devices2in the outer case body10can be ensured, and the volume energy density of the energy storage device2can be ensured.

Since the long side surface is more likely to be deformed during injection molding than the short side surface, the distance between the pair of first side walls12A and12B, which are the long side surfaces, is appropriately maintained by the pair of first fixing portions16A and16B, and the pair of second fixing portions31A and31B. Accordingly, deformation of the pair of first side walls12A and12B of the outer case body10can be effectively prevented or suppressed.

The central portion A1of the first side wall12A is more likely to be deformed during injection molding than the side portions A2where the first side wall12A is connected with the pair of second side walls13A and13B. Similarly, the central portion A1of the first side wall12B is more likely to be deformed during injection molding than the side portions A2where the first side wall12B is connected with the pair of second side walls13A and13B. Therefore, it is possible to effectively prevent or suppress deformation of the pair of first side walls12A and12B of the outer case body10by appropriately maintaining the distance between the central portions Al of the pair of first side walls12A and12B by the pair of first fixing portions16A and16B, and the pair of second fixing portions31A and31B.

Since the extension portion14A of the energy storage apparatus1is constituted of the reinforcing ribs15, and the extension portion14B is constituted of the reinforcing ribs15, it is unnecessary to provide the reinforcing ribs separately from the pair of extension portions14A and14B, and space saving can be realized.

In the Z direction, the position on the lid20side of the fixing portion60of the inner lid30and the outer case body10is located closer to the energy storage device2than the joint portion70in which the outer case body10and the lid20are heat-welded. Therefore, it is possible to prevent the hot plate80used for heat-welding the outer case body10and the lid20from interfering with the fixing portion60.

Since the inner lid30is bonded to the energy storage devices2, warp deformation of the inner lid30can be suppressed, and thus the distance L2between the pair of second fixing portions31A and31B can be appropriately maintained, and deformation of the pair of first side walls12A and12B of the outer case body10can be effectively prevented or suppressed.

Although the present invention has been described above with reference to the suitable first embodiment, the present invention is not limited to a specific embodiment, and various changes can be made within the scope of the gist of the present invention described in the claims.

For example, the bus bar cover50does not have to be fixed to the outer case body10.

The pair of first fixing portions16A and16B may be insertion holes, and the pair of second fixing portions31A and31B may be pins.

Both the pair of first fixing portions16A and16B, and the pair of second fixing portions31A and31B may be insertion holes, or pins separate from these may be prepared.

Furthermore, the pair of second side walls13A and13B may include a pair of first fixing portions such as a plurality of pins.

Although the first side walls12A and12B are specified to be the long side surfaces of the outer case body10in the first embodiment described above, embodiments of the present invention are not limited to this and include a case where the first side walls12A and12B are the short side surfaces of the outer case body10. For example, which surfaces the long side surfaces and the short side surfaces of the outer case body10become can be changed depending on a direction in which the energy storage devices2are arranged. Specifically, when eight energy storage devices2are arranged in the Y direction unlike the first embodiment described above, the first side walls12A and12B disposed in the XZ plane become the short side surfaces of the outer case body10, and the second side walls13A and13B disposed on the YZ plane become the long side surfaces of the outer case body10.

As described above, when the array direction of the energy storage devices2is the Y direction, the pair of first side walls12A and12B are walls extending in a direction orthogonal to the array direction of the energy storage devices2and become the short side surfaces of the outer case body10. That is, the pair of first fixing portions16A and16B provided on the pair of first side walls12A and12B are disposed on one side and the other side of the outer case body10in the Y direction (array direction of the energy storage devices2).

The case of the energy storage devices2may expand over time, and the outer case body10of the energy storage apparatus1may be deformed under the influence thereof. In particular, in a case where the electric storage devices2have a prismatic shape as in the first embodiment described above, the Y direction in which the electric storage devices2are arranged (stacked) coincides with a direction in which the energy storage devices2are likely to expand. Therefore, the pair of first side walls12A and12B, which are walls extending in a direction orthogonal to the array direction of the energy storage devices2, may be most affected under the influence and deform outward in the Y direction. In this aspect, as described above, the pair of first fixing portions16A and16B fixed to the inner lid30are provided on the pair of first side walls12A and12B, and are disposed on one side and the other side of the outer case body10in the Y direction (array direction of the energy storage device2). As a result, the force of the plurality of energy storage devices2attempting to deform outward in the Y direction is consumed as a force for pulling the inner lid30outward in the Y direction, and thus it is possible to suppress deformation of the pair of first side walls12A and12B outward in the Y direction.

In the aspect described above, the short side surfaces and the long side surfaces of the outer case body10have been described by taking a direction in which the energy storage devices2are arranged as an example. However, the short side surfaces and the long side surfaces of the outer case body10may be interchanged by changing the number of the energy storage devices2to be arranged, or changing the case size of the energy storage devices2. Also in this case, by providing the pair of first fixing portions16A and16B for attaching the inner lid30to the pair of first side walls12A and12B, the effects described above are exhibited in each of a case where the pair of first side walls12A and12B become the long side surfaces and a case where the pair of first side walls12A and12B become the short side surfaces.

Further speaking, in a case where the area of the long side surface of the case of one energy storage device2is equal to the total area of the short side surfaces of the cases of the plurality of energy storage devices gathered together, the area of the first side walls12A and12B and the area of the second side walls13A and13B become equal. In this case, although the concept of a short side surface and a long side surface is eliminated, the effect of suppressing deformation of the outer case body, which is the effect of the present invention, is exhibited without a change.

Second Embodiment

Next, the second embodiment will be described in detail, focusing on a coupling structure of an outer case body and an inner lid in an outer case.

Conventionally, an energy storage apparatus including an energy storage device and an outer case is known. For example, Patent Document 2 discloses a power supply device provided with a storage case that accommodates a power supply device body including an assembled battery having a plurality of battery cells aligned. Specifically, the storage case has a case body that accommodates the power supply device body, and a lid that closes an opening of the case body. The lid and the case body are fastened by screws respectively inserted into through holes provided at four corners of the lid. That is, the lid is coupled to the case body by the plurality of screws.

Like the storage case in the conventional power supply device, it is possible to firmly couple the inner lid and the outer case body in the outer case having a structure in which the outer case body and the member (inner lid) disposed in the opening of the outer case body are coupled using a plurality of screws (bolts). However, since the bolts and nuts are generally made of metal, when the number of bolts is increased in order to more firmly couple the inner lid and the outer case body, for example, problems such as an increase in the number of parts or an increase in the weight of the energy storage apparatus may occur. Since the work of turning the bolts (or nuts) is sequentially performed for each of the plurality of bolts, more firmly coupling the inner lid and the outer case body may lead to lowering of the manufacturing efficiency of the energy storage apparatus.

The present invention has been made by the inventor of the present application by newly focusing on the above problems, and it is a second object to provide an energy storage apparatus having an energy storage device and an outer case, which has a simple configuration and high reliability.

An energy storage apparatus according to an aspect of the present invention is an energy storage apparatus including an energy storage device and an outer case, in which the outer case has an outer case body that accommodates the energy storage device, and an inner lid that is disposed above the energy storage device, one of the outer case body and the inner lid has a pin, the other has a hole, and a tip portion of the pin is heat-caulked with the pin penetrating the hole.

According to this structure, the tip portion of the pin inserted into the hole is heat-caulked, and accordingly the outer case body and the inner lid are coupled to each other. Therefore, for example, the outer case body and the inner lid are firmly coupled to each other while the work for the coupling is facilitated as compared with a case where the outer case body and the inner lid are coupled using bolts. For example, even when the outer case is provided with a plurality of combinations of pins and holes, it is possible to heat-caulk the plurality of pins simultaneously or substantially simultaneously. Therefore, it is possible to improve the coupling force between the outer case body and the inner lid, and to efficiently manufacture an energy storage apparatus. As described above, the energy storage apparatus of this aspect is an energy storage apparatus with a simple configuration and high reliability.

The hole may be formed at a peripheral edge of the inner lid, and the pin may be formed at a position of the outer case body facing the peripheral edge of the inner lid so as to project toward the inner lid.

According to this configuration, the tip of the pin can be heat-caulked from above with the pin of the outer case body penetrating the hole of the inner lid. That is, the work of heat caulking can be easily performed. Accordingly, for example, the accuracy of the work is improved, and as a result, the reliability of the energy storage apparatus is improved.

The outer case body may be erected on an inner surface located beside the energy storage device and have a rib extending in an alignment direction of the inner lid and the outer case body, and the pin may be erected on an end portion of the rib on the inner lid side.

According to this configuration, the rib improves the strength of the outer case body, and the rib forms a structure that supports at least a part of the inner lid. Therefore, the inner lid is more stably supported by the outer case body. This contributes to improvement of the reliability of the energy storage apparatus.

A plurality of the pins may be provided on one of the outer case body and the inner lid, and the plurality of pins may be disposed at positions that do not have rotational symmetry with respect to the center of one of the outer case body and the inner lid when viewing the one in plan.

According to this configuration, the plurality of holes provided at the other of the outer case body and the inner lid are also disposed at positions that do not have rotational symmetry with respect to the center of the other. Accordingly, the one-to-one relationship between the plurality of pins and the plurality of holes is uniquely determined, so that it is easy to determine the orientation (posture) of the inner lid with respect to the outer case body when the inner lid is disposed on the outer case body. That is, in a case where the shape of the inner lid in plan view is a rotationally symmetric shape such as a regular polygon, the possibility that the inner lid is disposed (misplacement) in an erroneous orientation (posture) on the outer case body is reduced. Therefore, an event such as lowering of the manufacturing efficiency due to misplacement or damage to a member due to misplacement, which may cause lowering of the reliability of the energy storage apparatus, is unlikely to occur.

A plurality of the pins are provided on one of the outer case body and the inner lid, and the shape in plan view, the size, or the posture of one of the plurality of pins may be different from the shape in plan view, the size, or the posture of one or more other pins.

With this configuration where a combination of one of the plurality of pins and one of the plurality of holes is uniquely determined, it is easy to determine the orientation (posture) of the inner lid with respect to the outer case body when the inner lid is disposed on the outer case body. That is, in a case where the shape of the inner lid in plan view is a rotationally symmetric shape such as a regular polygon, the possibility that the inner lid is disposed (misplacement) in an erroneous orientation (posture) on the outer case body is reduced. Therefore, an event such as lowering of the manufacturing efficiency due to misplacement or damage to a member due to misplacement, which may cause lowering of the reliability of the energy storage apparatus, is unlikely to occur.

The inner lid may have a substantially rectangular shape in plan view, and one of the outer case body and the inner lid may be provided with N (N is a positive odd number) pins.

For example, assume that the shape of the inner lid in plan view is a shape that is recognized as a rectangle as a whole, and that three holes into which the pins of the outer case body are inserted are disposed at the peripheral edge of the inner lid. In this case, the inner lid has rotational symmetry at every 180°, while it is impossible to dispose the three pins on the outer case body so as to have rotational symmetry at every 180°. That is, the arrangement positions of the three pins at the outer case body are positions that do not have rotational symmetry at every 180°, and accordingly misplacement of the inner lid with respect to the outer case body does not occur.

With the present invention, it is possible to provide an energy storage apparatus with a simple configuration and high reliability.

The following description will explain an energy storage apparatus according to a second embodiment of the present invention and a modification example thereof with reference to the drawings.

In the following description, for example, a plus side in the X direction indicates a side of the X axis represented by the arrow direction, and a minus side in the X direction indicates a side opposite to the plus side in the X direction. The same applies to the Y direction and the Z direction.

[General description of energy storage apparatus1a]

The basic structure of an energy storage apparatus1aaccording to the present embodiment is common to the basic structure of the energy storage apparatus1according to the first embodiment. Hereinafter, in the description of the energy storage apparatus1a,description of items common to the energy storage apparatus1according to the first embodiment may be omitted. Since there is no significant difference in appearance between the energy storage apparatus1aand the energy storage apparatus1, an external perspective view of the energy storage apparatus1ais omitted.

A general description of the energy storage apparatus1aaccording to the second embodiment will be given with reference toFIG. 8.FIG. 8is an exploded perspective view illustrating each component of a case where the energy storage apparatus1aaccording to the second embodiment is disassembled.

As illustrated inFIG. 8, the energy storage apparatus1aincludes an energy storage device2, and an outer case110that accommodates the energy storage device2. In the present embodiment, the outer case110accommodates eight energy storage devices2. The outer case110has an outer case body112that accommodates the plurality of energy storage devices2, and an inner lid117that is disposed above the plurality of energy storage devices2. In the present embodiment, the outer case110further has a lid111disposed so as to cover an upper side of the inner lid117. Inside the outer case110, a plurality of bus bars133held on the inner lid117, bus bar covers160and170, and a connection unit180including a control circuit or the like are accommodated in addition to the plurality of energy storage devices2.

The outer case110is a rectangular (box-shaped) case (module case) that constitutes an outer case of the energy storage apparatus1a.That is, the outer case110is a member that fixes the plurality of energy storage devices2, the inner lid117, and the like at predetermined positions and protects these elements from an impact or the like.

The lid111of the outer case110is a rectangular member that closes the opening of the outer case body112and has an external terminal91on the positive electrode side and an external terminal92on the negative electrode side. The external terminals91and92are electrically connected with the plurality of energy storage devices2via the connection unit180and bus bars133, and the energy storage apparatus1acharges electricity from the outside or discharges electricity to the outside via the external terminals91and92. The external terminals91and92are formed of, for example, a conductive member made of metal such as aluminum or aluminum alloy. The outer case body112is a bottomed rectangular tubular housing (cabinet) provided with an opening and accommodates the energy storage devices2and the like.

Each energy storage device2has a flat rectangular parallelepiped shape (prismatic shape), and eight energy storage devices2are arranged in the X direction in the present embodiment.

Specifically, each energy storage device2includes a case21made of metal, and electrode terminals22(positive electrode terminal and negative electrode terminal) made of metal are provided on a lid part of the case21. The electrode terminals22(positive electrode terminal and negative electrode terminal) are each an electrode terminal that is disposed so as to project from the lid part of the case21toward the inner lid117(upward, that is, toward the plus side in the Z direction). The electrode terminals22are connected with the external terminals91and92via at least one bus bar133and the connection unit180, so that the energy storage apparatus1acan charge electricity from the outside or discharge electricity to the outside. The lid part of the case21may be provided with an electrolyte solution filling part or the like for electrolyte solution filling. Inside the case21, an electrode assembly (also referred to as an energy storage element or a power generating element), a current collector (positive electrode current collector and negative electrode current collector), and the like are disposed, and an electrolyte solution (nonaqueous electrolyte) or the like is enclosed, though detailed description is omitted.

Each bus bar133is a rectangular plate-shaped member that is disposed on at least two energy storage devices2in a state held by the inner lid117and is electrically connected with the electrode terminals22of the at least two energy storage devices2. In the present embodiment, five bus bars133are used for each connecting two storage devices2in parallel to form four sets of energy storage device groups, and the four sets of energy storage device groups are connected in series.

The connection unit180is a unit having a plurality of bus bars, a control board, and the like, and connects the energy storage device groups including eight energy storage devices2with the external terminals91and92. In the present embodiment, the connection unit180is fixed to the inner lid117. The detection circuit and the control circuit may be formed on separate substrates. The connection unit180may not have a control board. In this case, for example, a control device disposed outside the energy storage apparatus1amay control charging and discharging of each energy storage device2.

The inner lid117is an example of an inner lid to be disposed above the plurality of energy storage devices2(on a side where the electrode terminals22are disposed), and is a member that holds the bus bars133in the present embodiment. More specifically, the inner lid117is a member that can hold the plurality of bus bars133, the connection unit180, other wirings (not shown), and the like, and can restrict the positions of these members or the like. The inner lid117is provided with a plurality of bus bar openings117athat hold each of the plurality of bus bars133and expose a part of each of the plurality of bus bars133toward the plurality of energy storage devices2. The inner lid117is fixed to the outer case body112by a method to be described later, and thus also has a role of restricting upward (plus side in the Z direction) movement of the plurality of energy storage devices2, for example.

The inner lid117disposed above the plurality of energy storage devices2may be called, for example, a “bus bar frame”.

Each of the bus bar covers160and170is a member made of resin that covers the plurality of bus bars133from above, and has a role of electrically insulating the plurality of bus bars133and the connection unit180from each other, for example.

[Coupling structure of Bus Bar Plate and Outer Case Body]

In the energy storage apparatus1aconfigured as described above, the inner lid117is coupled to the outer case body112of the outer case110by heat caulking. Hereinafter, the coupling structure of the inner lid117and the outer case body112according to the present embodiment will be described with reference toFIGS. 9 to 11.

FIG. 9is a perspective view illustrating the structural relationship between the outer case body112, the inner lid117, and the bus bar covers160and170according to the second embodiment.FIG. 10Ais a plan view of the outer case body112according to the second embodiment.FIG. 10Bis a plan view of the inner lid117according to the second embodiment.FIG. 10Cis a plan view of the bus bar covers160and170according to the second embodiment.FIG. 11is a cross-sectional perspective view illustrating a coupling portion of the outer case body112and the inner lid117according to the second embodiment.FIG. 11illustrates a perspective view of the energy storage apparatus1acut along the YZ plane passing through line V-V inFIG. 10A, and other elements such as the energy storage devices2are not shown.

In the present embodiment, the outer case body112of the outer case110is provided with a plurality of pins115as illustrated inFIGS. 9 and 10A. Specifically, eight pins115denoted by symbols115ato115hinFIG. 10Aare provided on the outer case body112. The pin115is an example of a pin provided at the pair of first fixing portions or the pair of second fixing portions. In the present embodiment, the pins115ato115dcorrespond to the first fixing portion16A in the first embodiment, and the pins115eto115hcorrespond to the first fixing portion16B in the first embodiment.

Each of these pins115is inserted into a hole118provided at the inner lid117, and a tip portion of the pin115is heat-caulked. Specifically, inFIG. 10B, eight holes118denoted by symbols118ato118hare provided at the inner lid117, and a pin115denoted by the same alphabet as one of the eight holes118is inserted into this hole. For example, the pin115ais inserted into the hole118a,and the pin115bis inserted into the hole118b.Furthermore, a tip portion of each pin115is heat-caulked with the pin115penetrating a hole118. Each hole118is an example of an insertion hole provided at the pair of first fixing portions or the pair of second fixing portions. In the present embodiment, the holes118ato118dcorrespond to the second fixing portion31A in the first embodiment, and the holes118eto118hcorrespond to the second fixing portion31B in the first embodiment.

That is, a tip portion of each pin115is heated and melted, and then cooled and solidified, so that a head116is formed at the tip portion of the pin115(pin115binFIG. 11) as illustrated inFIG. 11. Here, the head116is a part integrally provided with the pin115and has a larger outer diameter than a part of the pin115between the base and the head116. Since the head116is a part formed by melting and then solidifying, the head116is formed in a shape in close contact with the object to be coupled (bus bar cover170inFIG. 11). Alternatively, the head116is formed in a state of being fused together with the object to be coupled. Accordingly, the inner lid117is firmly coupled to the outer case body112.

In the present embodiment, the bus bar cover160or170is fixed to the outer case body112together with the inner lid117at four of the eight heat-caulking portions on the outer case110. Specifically, as illustrated inFIG. 10C, the bus bar cover160is provided with holes165fand165g,and the bus bar cover170is provided with holes175band175c.Into each of these holes165f,165g,175b,and175c,a pin115penetrating the hole118of the inner lid117disposed at a corresponding position is inserted, and the tip portion of the pin115is heat-caulked in this state. In this way, the bus bar covers160and170are coupled to the outer case body112by heat caulking together with the inner lid117, so that the manufacturing efficiency of the energy storage apparatus1acan be improved, and the bus bar covers160and170can be firmly fixed to the outer case body112.

At the bus bar cover160, openings166hand166eare arranged on the same line with the holes165gand165f.Heads116of pins115hand115ethat are heat-caulked without penetrating the bus bar cover160are disposed in these openings166hand166e.At the bus bar cover170, openings176aand176dare arranged on the same line with the holes175band175c.Heads116of pins115aand115dthat are heat-caulked without penetrating the bus bar cover170are disposed in these openings176aand176d.

Here, in the present embodiment, the outer case body112has the pins115, and the inner lid117has the holes118into which the pins115are inserted. However, the arrangement positions of the pins115and the holes118are not limited to this, and one of the outer case body112that accommodates an energy storage device2, and the inner lid (inner lid117in the present embodiment) that is disposed above the energy storage device2may have the pins115, while the other may have the holes118. For example, a flange that spreads outward is provided on the periphery of the upper opening of the outer case body112, and a hole118is formed at the flange. Apart facing the flange may be provided at the peripheral edge of the inner lid117, and a pin115projecting downward may be provided at that part. Even in this case, the outer case body112that accommodates the energy storage device2, and the inner lid117serving as an inner lid disposed above the energy storage device2can be firmly coupled by utilizing heat caulking.

As described above, the energy storage apparatus1aaccording to the present embodiment is an energy storage apparatus1aincluding the energy storage device2and the outer case110, and the outer case110has the outer case body112that accommodates the energy storage device2, and the inner lid117disposed above the energy storage device2. One of the outer case body112and the inner lid117has a pin115while the other has a hole118, and the tip portion of the pin115is heat-caulked with the pin115penetrating the hole.

According to this configuration, the tip portion of the pin115inserted into the hole118is heat-caulked, and accordingly the outer case body112and the inner lid117are coupled to each other. Therefore, for example, the outer case body112and the inner lid117can be firmly coupled. The work for coupling is facilitated in comparison with a case where the outer case body112and the inner lid117are coupled using bolts. For example, even when the outer case110is provided with a plurality of combinations of the pins115and the holes118as in the present embodiment, a plurality of pins115can be heat-caulked simultaneously or substantially simultaneously by using a device for performing heat caulking. Therefore, it is possible to improve the coupling force between the outer case body112and the inner lid117, and to efficiently manufacture the energy storage apparatus1a.As described above, the energy storage apparatus1aaccording to the present embodiment is an energy storage apparatus1awith a simple configuration and high reliability

If a bolt is used to couple the outer case body112and the inner lid117, it is necessary to provide a hole at one of the outer case body112and the inner lid117, and to embed a bolt head or a nut in the other. Consequently, a region for embedding the head of a screw or a nut is essential in the other side, when viewed from the axial direction of the bolt. This may waste the space inside the outer case110, for example. In this regard, the energy storage apparatus1aaccording to the present embodiment may be provided with a convex pin115at one of the outer case body112and the inner lid117toward the other side. Therefore, it is unnecessary to provide an extra region at the base part of the pin115. For example, even if the energy storage apparatus1ais subjected to an excessive impact and the pin115made of resin is scattered, the scattered pin115is unlikely to damage other members.

The heat caulking is advantageous in that, for example, a waiting time for curing adhesive is not required in comparison with a case where an adhesive is used instead of heat caulking for coupling the outer case body112and the inner lid117.

More specifically, in the energy storage apparatus1aaccording to the present embodiment, the holes118are formed at the peripheral edge of the inner lid117as illustrated inFIG. 10B, for example. As illustrated inFIG. 10A, for example, the pins115are formed at positions of the outer case body112facing the peripheral edge of the inner lid117so as to project toward the inner lid117.

According to this configuration, the tip of each pin115can be heat-caulked from above with the pin115of the outer case body112penetrating a hole118of the inner lid117. That is, the work of heat caulking can be easily performed. Accordingly, for example, the accuracy of the work is improved, and as a result, the reliability of the energy storage apparatus1ais improved.

In the energy storage apparatus1aaccording to the present embodiment, a plurality of ribs113are provided on the inner surface112aof the outer case body112as illustrated inFIGS. 9 and 10A, for example. The pins115are provided on the upper end of a part of the plurality of ribs113. That is, in the present embodiment, the outer case body112is erected on the inner surface112alocated beside the energy storage devices2, and has ribs113extending in the alignment direction (Z direction in the present embodiment) of the inner lid117and the outer case body112. The pins115are erected on an end portion of the ribs113on the inner lid117side. The plurality of ribs113in the present embodiment are an example of the extension portion.

By providing the ribs113on the inner surface112aof the outer case body112in this manner, the strength of the outer case body112is improved. In this way, the pin115is provided on an upper end of the ribs113extending in a direction parallel to the projecting direction of the pins115, so that the inner lid117is supported by the ribs113. Therefore, the inner lid117is more stably supported by the outer case body112. This contributes to improvement of the reliability of the energy storage apparatus1a.

In the energy storage apparatus1aaccording to the present embodiment, the plurality of pins115are provided on the outer case body112, and the plurality of pins115are disposed at positions that do not have rotational symmetry with respect to the center of the outer case body112when viewing the outer case body112in plan. Specifically, in a substantially rectangular outer case body112in plan view as illustrated inFIG. 10A, the eight pins115(pins115ato115hinFIG. 10A) are disposed at positions that do not have rotational symmetry with respect to a center point Pa of the outer case body112. In other words, the positions of the eight pins115coincide before and after rotation only when the outer case body112is rotated about the center point Pa by an integral multiple of 360°. Consequently, the same applies to the eight holes118into which the eight pins115are inserted. That is, in the substantially rectangular inner lid117in plan view as illustrated inFIG. 10B, the eight holes118(holes118ato118hinFIG. 10B) are disposed at positions that do not rotational symmetry with respect to a center point Pb of the inner lid117. In other words, the positions of the eight holes118coincide before and after the rotation only when the inner lid117is rotated about the center point Pb by an integral multiple of 360°.

In the present embodiment, the inner lid117has a substantially rectangular shape in plan view as described above. Therefore, when disposing the inner lid117at the outer case body112having the posture illustrated inFIG. 10A, for example, it is not easy to immediately determine whether the inner lid117is to be disposed in the orientation (posture) illustrated inFIG. 10Bor to be disposed in the orientation (posture) rotated by 180° about the center point Pb, focusing on the outer shape of the inner lid117. That is, in a case where the shape of the inner lid in plan view to be disposed on the outer case body112is a shape that is rotationally symmetric by a predetermined angle (e.g., 360°/N (N is an integer of 2 or more)) such as a rectangle, a regular polygon, or an ellipse, the outer shape makes it difficult to determine in which orientation (posture) the inner lid is to be disposed on the outer case body112. Furthermore, in the present embodiment, the inner lid disposed on the outer case body112is the inner lid117that holds the plurality of bus bars133, and the positions of the plurality of electrode terminals22provided at the plurality of energy storage devices2are also rotationally symmetric positions at every 180° as with the inner lid117. That is, even when the inner lid117is rotated 180° about the center point Pb from the normal posture, two or more joinable electrode terminals22exist immediately below each of the bus bars133. Consequently, if the inner lid117in a state rotated 180° from the normal posture is disposed on the outer case body112(that is, if misplacement occurs), the work of joining the bus bar133and the electrode terminal22becomes possible, and accordingly a manufacturing error may occur. Consequently, suppression of misplacement of the inner lid117is important from the viewpoint of improving the production efficiency of the energy storage apparatus1a.

In this regard, in the present embodiment, the one-to-one relationship between the plurality of pins115of the outer case body112and the plurality of holes118of the inner lid117is uniquely determined. That is, by comparing the arrangement layout of the plurality of holes118in the inner lid117with the arrangement layout of the plurality of pins115in the outer case body112, it is possible to easily determine in which orientation (posture) the inner lid117is to be disposed on the outer case body112. That is, the possibility of misplacement of the inner lid117with respect to the outer case body112is reduced. Therefore, an event such as lowering of the manufacturing efficiency due to misplacement or damage to a member due to misplacement, which may cause lowering of the reliability of the energy storage apparatus1a,is unlikely to occur.

The above effects are similarly obtained when the outer case body112has a plurality of holes118and the inner lid117has a plurality of pins115. That is, in a case where the plurality of pins115are provided on the inner lid117and the plurality of pins115are disposed at positions that do not have rotational symmetry with respect to the center of the inner lid117in plan view, the possibility of misplacement of the inner lid117with respect to the outer case body112is reduced.

In the present embodiment, two bus bar covers160and170are disposed corresponding to the plurality of bus bars133aligned in two rows as illustrated inFIG. 8, for example, and both of these two bus bar covers160and170have long and similar shapes. Consequently, for example, it is not easy to determine which of the bus bar covers160and170is to be disposed on the plus side (or minus side) in the Y direction in the outer case body112in the posture illustrated inFIG. 10A, for example, based on the outer shape of the bus bar covers160and170. However, the arrangement layout of the holes165gand165fin the bus bar cover160and the arrangement layout of the holes175band175cin the bus bar cover170are obviously different. Specifically, the holes175band175cin the bus bar cover170are disposed relatively close to each other, while the holes165gand165fin the bus bar cover160are disposed relatively far from each other. Therefore, comparing the arrangement layout of the plurality of holes in each of the bus bar covers160and170with the arrangement layout of the plurality of pins115in the outer case body112, it can be easily judged that the bus bar cover170is to be disposed on the plus side in the Y direction. That is, the possibility of misplacement of the bus bar covers160and170with respect to the outer case body112is reduced. Therefore, an event such as lowering of the manufacturing efficiency due to misplacement or damage to a member due to misplacement, which may cause lowering of the reliability of the energy storage apparatus1a,is unlikely to occur.

Although the energy storage apparatus1aaccording to the second embodiment has been described above, the outer case110provided in the energy storage apparatus1amay include a pin or a hole of a form different from the form illustrated inFIGS. 9 to 11. Thus, the following description will explain a modification example of a pin and a hole for coupling the outer case body and the inner lid in the outer case110, focusing on differences from the above second embodiment.

MODIFICATION EXAMPLE

FIG. 12Ais a plan view of an outer case body212of an outer case according to a modification example of the second embodiment.FIG. 12Bis a plan view of an inner lid217of the outer case according to the modification example of the second embodiment. In order to clearly show the arrangement positions and shapes of the pins and holes, illustrations other than the structures related to the pins and holes are omitted, and the overall shapes of the outer case body212and the inner lid217are schematically illustrated inFIGS. 12A and 12B. InFIG. 12B, dots are drawn at the regions of the plurality of holes formed at the inner lid217.

The outer case body212illustrated inFIG. 12Ais a member that accommodates a plurality of energy storage devices2as with the outer case body112according to the second embodiment, and the inner lid217illustrated inFIG. 12Bis an example of an inner lid disposed above the plurality of energy storage devices2as with the inner lid117according to the second embodiment. That is, the outer case110according to the present modification example includes the outer case body212and the inner lid217.

In the present modification example, the outer case body212has four pins215ato215d,and each of these four pins215ato215dis disposed at the upper end of ribs213. The inner lid217has four holes218ato218d.A pin denoted by the same alphabet as one of these four holes218ato218dis inserted into this hole. For example, the pin215ais inserted into the hole218a,and the pin215bis inserted into the hole218b.Furthermore, a tip portion of each pin is heat-caulked with the pin penetrating a hole.

These four pins215ato215dare disposed at positions that have rotational symmetry in plan view. That is, the four holes218ato218dcorresponding to the four pins215ato215dare similarly disposed at positions of the inner lid217that have rotational symmetry in plan view. However, in this modification example, the shape of the pin215aamong the pins215ato215dis different from the other pins215bto215d.That is, the shape of the hole218acorresponding to the pin215ais different from the other holes218bto218d.Consequently, when disposing the inner lid217on the outer case body212, it is easy to associate the pin215aand the hole218awith each other, and as a result, it is also possible to determine the orientation (posture) of the inner lid217with respect to the outer case body212.

As described above, in this modification example, the outer case body212is provided with the plurality of pins215ato215d,and the shape of one pin215aamong the plurality of pins215ato215din plan view is different from the shape of the other pins215bto215din plan view.

With this configuration where a combination of one of the plurality of pins and one of the plurality of holes is uniquely determined, it is easy to determine the orientation (posture) of the inner lid217with respect to the outer case body212when the inner lid217is disposed on the outer case body212. That is, in a case where the shape of the inner lid217in plan view is a shape having rotational symmetry at every predetermined angle as illustrated inFIG. 12B, the possibility of misplacement of the inner lid217is reduced. Therefore, an event such as lowering of the manufacturing efficiency due to misplacement or damage to a member due to misplacement, which may cause lowering of the reliability of the energy storage apparatus1a,is unlikely to occur.

The size or the posture of one pin215aamong the plurality of pins215ato215din plan view may be different from the size or the posture of the other pins215bto215d.For example, assume that all of the plurality of pins215ato215dhave an equilateral triangle shape in plan view as with the pin215a.In this case, it is easy to identify the combination of the pin215aand the hole218awhen the posture of the pin215ais such that the vertices of the equilateral triangle in plan view face the plus side in the Y direction, and the postures of the other pins215bto215dare such that the vertices of the equilateral triangle in plan view face the minus side in the Y direction. The same applies when the size of the pin215adiffers from the size of the other pins215bto215din plan view.

The shape in plan view, the size, or the posture of one pin215aamong the plurality of pins215ato215ddoes not have to be different from the shape in plan view, the size, or the posture of all of the other pins215bto215d.For example, the shape of the pin215ain plan view may be the same as the shape of the pin215bor215din plan view, and may be different from the shape of the other two pins in plan view. In this case, it is also easy to determine the orientation (posture) of the inner lid217with respect to the outer case body212.

The shape of each of the plurality of pins215ato215din plan view may be different from all other pins. That is, each of the plurality of pins215ato215dmay have a unique shape in plan view. In this case, it is also easy to determine the orientation (posture) of the inner lid217with respect to the outer case body212.

(Other Embodiments Related to Second Embodiment)

The energy storage apparatus according to the present invention has been described above based on the second embodiment and a modification example thereof. However, the present invention is not limited to the above second embodiment and modification example. Without departing from the gist of the present invention, forms obtained by applying various changes that can be made by those skilled in the art to the above second embodiment or modification, and forms constructed by combining a plurality of the above-described components may also be included in the scope of the present invention.

In the second embodiment, the inner lid117may also be bonded to the plurality of energy storage devices2as in the first embodiment. Accordingly, the inner lid117functions as a member that restrains the plurality of energy storage devices2. This is significant when the plurality of energy storage devices2aligned in the outer case body112are not restrained in the alignment direction. The inner lid117is temporarily fixed to the outer case body112by inserting pins115of one of the inner lid117and the outer case body112into holes118of the other. Consequently, when the inner lid117and the plurality of energy storage devices2are bonded to each other, the inner lid117can be temporarily fixed without using a jig until the adhesive is solidified.

Although there are a plurality of combinations of pins and holes that couple the outer case body and the inner lid in the second embodiment and the modification example, only one combination may be provided. For example, in a case where only one pin is provided on the outer case body and only one hole is provided on the inner lid and the position of the pin is a position other than the center of the outer case body in plan view, the position of the pin is surely a position that does not have rotational symmetry with respect to the center of the outer case body. The position of the hole at the inner lid is also surely a position that does not have rotational symmetry with respect to the center of the inner lid. Consequently, even when the shape of the inner lid in plan view has rotational symmetry at every predetermined angle (other than 360°), misplacement of the inner lid with respect to the outer case body does not occur. In this case, regarding a part different from the arrangement position of the pin and the hole, the outer case body and the inner lid may be coupled by predetermined means such as bonding, fitting, welding, or screwing.

For example, in a case where the inner lid has a substantially rectangular shape in plan view and the number of combinations of pins and holes is an odd number, misplacement of the inner lid with respect to the outer case body does not occur. That is, the inner lid has a substantially rectangular shape in plan view, and N (N is a positive odd number) pins may be provided on one of the outer case body and the inner lid. To give a specific example, for example, assume that the shape of the inner lid in plan view is a shape that is recognized as a rectangle as a whole, and the peripheral edge of the inner lid has three holes into which the pins of the outer case body are inserted. That is, assume that only three pins are disposed at positions of the outer case body facing the peripheral edge of the inner lid. In this case, the inner lid has rotational symmetry at every 180°, while it is impossible to dispose the three pins on the outer case body so as to have rotational symmetry at every 180°. That is, the arrangement positions of the three pins at the outer case body are positions that do not have rotational symmetry at every 180°, and accordingly misplacement of the inner lid with respect to the outer case body does not occur.

Although the plurality of pins are disposed in a distributed manner only at peripheral edges of the outer case body on the plus side and the minus side in the Y direction (i.e., peripheral edges parallel to the X direction) in plan view in the second embodiment and the modification example, the arrangement position of the pin is not limited to this. For example, one or more pins may be disposed only on a peripheral edge on any one of the plus side and the minus side of the outer case body in the Y direction in plan view. For example, one or more pins may be disposed on each of a peripheral edge of the outer case body on any one of the plus side and the minus side in Y direction, and a peripheral edge of the outer case body on any one of the plus side and the minus side in the X direction. For example, only one pin may be provided on each of peripheral edges of the outer case body on the plus side and the minus side in the Y direction (or the plus side and the minus side in the X direction). That is, only two sets of combinations of pins and holes may be used to couple the outer case body and the inner lid, and, in this case, these two sets may be disposed at positions facing each other in plan view. Accordingly, for example, the stability of the inner lid with respect to the outer case body is improved.

That is, the position of the combination of the pin and the hole disposed on the outer case body and the inner lid may be appropriately determined in consideration of, for example, the stability after the inner lid and the outer case body are coupled, the ease of heat caulking work, or the like. As described above, the arrangement positions of the combinations of one or more pins and holes is judged in consideration of matters such as arranging a plurality of pins at positions that do not have rotational symmetry in plan view, so that an effect of suppressing misplacement of the inner lid with respect to the outer case body can be obtained.

In the second embodiment and the modification example, the inner lid coupled to the outer case body by the combination of the pin and the hole is a bus bar plate. However, the inner lid coupled to the outer case may be a member different from the bus bar plate as long as the member extends over the opening of the outer case body.

In the second embodiment, the lid111disposed above the inner lid117may be realized as an inner lid that is coupled to the outer case body by the combination of pins and holes. That is, a pin provided on one of the outer case body112and the lid111is penetrated through a hole provided on the other and a tip portion is heat-caulked, so that the lid111can be coupled to the outer case body112.

A tray or a frame that does not hold the plurality of bus bars133and holds electric devices such as a control board may be treated as an inner lid that is coupled to the outer case body using a combination of a pin and a hole. A member that does not have a role of holding any member and is disposed above the plurality of energy storage devices2to restrict upward movement of the plurality of energy storage devices2may be treated as an inner lid. That is, an inner lid that is coupled to the outer case body using a combination of a pin and a hole does not have to have a shape that completely covers the plurality of energy storage devices2. For example, any member that extends from one end to the other end of an opening of an outer case body, which is located above the plurality of energy storage devices2, in a predetermined direction in plan view can be treated as an inner lid that is coupled to the outer case body using a combination of a pin and a hole. In other words, any member that is disposed across the space of a region facing the plurality of energy storage devices2above the plurality of energy storage devices2can be treated as an inner lid that is coupled to the outer case body using a combination of a pin and a hole. That is, it is possible to obtain a highly reliable energy storage apparatus by providing a pin on one of the member and the outer case body, and heat-caulking a tip portion of the pin with the pin penetrating a hole provided on the other.

The outer case provided at the energy storage apparatus1adoes not have to have a box shape that covers the plurality of energy storage devices2from the entire circumference. For example, the outer case body of the outer case may be composed of end plates disposed on both sides in the array direction of the plurality of energy storage devices2(X direction in the second embodiment), and a connecting member that connects these end plates. In this case, for example, a plurality of pins are provided on an upper end of the connecting member, and a plurality of holes are provided at the bus bar plate. Furthermore, the tip portion is heat-caulked with each of the plurality of pins penetrating a hole. By such a process, it is also possible to firmly couple the bus bar plates as the inner lid disposed above the plurality of energy storage devices2to the outer case body (combination of the pair of end plates and the connecting member).

A form constructed by arbitrarily combining the components included in the first and second embodiments and modification example thereof is also included in the scope of the present invention.

INDUSTRIAL APPLICABILITY

The present invention can be applied to an energy storage apparatus including an energy storage device such as a lithium ion secondary battery.

DESCRIPTION OF REFERENCE SIGNS

1: energy storage apparatus

2: energy storage device

3,110: outer case

10,112,212: outer case body

11: bottom wall

12a,12b:first side wall

13A,13B: second side wall

17: first pin

18: second pin

32: first insertion hole

33: second insertion hole

40,133: bus bar

50,160,170: bus bar cover

51: third insertion hole

70: joint portion

80: hot plate

91,92: external terminal

117a:bus bar opening

180: connection unit