Battery pack

Abstract

Provided is a battery pack wherein an external output terminal that is exposed from an exterior case in which a battery assembly is accommodated is fixed to an output bus bar. The external output terminal is composed of a clinching member, and the clinching member is fixed to the output bus bar in a perpendicular orientation by press-fitting a fixing end of the clinching member into a connection port in the output bus bar. A terminal insertion port for passing the clinching member through a fixing-receiving portion to which the external output terminal is fixed is opened in the exterior case. A chamfered portion is provided to one among the opening edge of the connection port and the opening edge of the terminal insertion port, which face each other, and an annular rubber-like elastic body is disposed on the chamfered portion. In a state in which the output bus bar is fixed to the fixing-receiving portion, a seal is formed by the rubber-like elastic body, which is press-fitted between the chamfered portion and the outer peripheral surface of the clinching member, thereby fixing the external output terminal to the exterior case using a waterproof structure.

Description

Battery pack

[0001] The present invention relates to a battery pack having a large number of battery cells housed in an outer case, and more particularly to a battery pack in which external output terminals exposed from the outer case are arranged on the outer case in a waterproof structure.

[0002] Battery packs have been developed that house a large number of rechargeable battery cells housed in an exterior case. Such battery packs are used as power sources for electric vehicles, or for electric heavy machinery, forklifts, and the like. Some of these power supply devices have external output terminals exposed on the exterior case for connection to an external device to charge and discharge the built-in battery cells. For example, in battery packs used outdoors, the external output terminals located on the exterior case are required to be waterproof and fixed to the exterior case to prevent rainwater from entering.

[0003] JP 2011-103259 A

[0004] An object of the present invention is to provide a battery pack in which external output terminals exposed from an outer case can be fixed to the outer case simply and easily with a waterproof structure while reducing manufacturing costs.

[0005] A battery pack according to one aspect of the present invention includes a battery pack including a plurality of battery cells, an outer case housing the battery pack, an external output terminal positioned outside the outer case, and an output bus bar having the external output terminal fixed to a first end thereof and connecting the output terminal of the battery pack to a second end thereof. The external output terminal is formed of a clinching member having a cylindrical outer shape, and the output bus bar has a connecting port opened at the first end thereof, with a fixed end of the clinching member press-fitted into the connecting port, thereby fixing the clinching member in a vertical position and closing the fixed end side of the clinching member. The outer case has a surface plate that defines a fixed portion to which the external output terminal is fixed, and a terminal insertion port, through which the tubular main body portion passes, opened in the fixed portion. At least one of the opening edges of the connecting port and the terminal insertion port, which face each other, is provided with a chamfered portion along the opening edge. Furthermore, an annular rubber-like elastic body through which the clinching member is inserted is disposed at the opening edge of the connecting port of the output bus bar, at the boundary with the clinching member, and when the clinching member is inserted into the terminal insertion port and the output bus bar is fixed to the fixed portion, a seal is formed between the opening edge of the connecting port, the opening edge of the terminal insertion port, and the outer peripheral surface of the clinching member via the elastically deformable rubber-like elastic body, thereby fixing the external output terminal to the outer case in a waterproof structure.

[0006] The battery pack of the present invention has a simple structure without requiring special processing of the clinching member, and yet has the advantage that the output bus bar to which the clinching member is fixed can be fixed to the outer case to ensure waterproofing.

[0007] 1. A perspective view of a battery pack according to an embodiment of the present invention. 1. An exploded perspective view of the battery pack shown in FIG. 1. 2. A rear perspective view of the battery pack shown in FIG. 2, seen from below. 3. An exploded perspective view of the battery pack assembly of the battery pack shown in FIG. 2. 4. A block diagram of the battery pack shown in FIG. 1. 5. A plan view of the battery pack shown in FIG. 1. 6. A cross-sectional view of the lid case of the battery pack shown in FIG. 6, taken along line VII-VII. 7. A cross-sectional view of the lid case of the battery pack shown in FIG. 6, taken along line VIII-VIII. 8. An exploded cross-sectional view of the lid case and output bus bar shown in FIG. 7. 9. A perspective view of an output bus bar to which a clinching member is fixed. 10. An enlarged cross-sectional view showing an O-ring being disposed on the clinching member and the output bus bar. 11. An enlarged cross-sectional view showing an O-ring waterproofing the clinching member, the output bus bar, and the fixed portion. 12. An exploded cross-sectional view showing an O-ring being press-fitted into the connecting port of the output bus bar. 13. An enlarged cross-sectional view showing another example of an O-ring waterproofing the clinching member, the output bus bar, and the fixed portion. 14. An exploded cross-sectional view of the waterproof structure shown in FIG. 15. 16. An enlarged cross-sectional view showing another example of an external output terminal. 17 is an enlarged cross-sectional view showing an example of a waterproof structure for an external output terminal of a battery pack according to a comparative example;

[0008] First, we will explain one of the key features of the present invention. Some battery packs, which house a battery pack having a large number of battery cells housed in an outer case, have external output terminals that are fixed to the outer case in a waterproof structure so that the external output terminals are exposed from the outer case. For such battery packs, a structure using clinching nuts for the external output terminals has been developed. An example of a waterproof structure for the external output terminals in this battery pack is shown in Figures 17 and 18.

[0009] The waterproof structure shown in these figures has a clinching nut 95 press-fitted into a connecting port 92 provided in the output bus bar 91 and fixed therein, and an outer case 93 has a through hole 94 opened therein for guiding the clinching nut 95. To arrange the clinching nut 95 in the outer case 93 in a waterproof structure, the clinching nut 95 shown in the figures has a ring-shaped outer circumferential groove 96 formed along its outer circumferential surface, and an O-ring 97 is arranged in this outer circumferential groove 96. The O-ring 97 arranged on the outer circumferential surface of the clinching nut 95 abuts against the open end face of a through hole 94 provided in the outer case 93 while fixing the output bus bar 91 to the inner surface of the outer case 93, and elastically deforms to seal the contact portion with the open end face of the through hole 94, thereby achieving a waterproof structure.

[0010] In the above structure, the clinching nut 95 needs to be machined into a special shape, which necessitates a custom-made clinching nut 95, resulting in high manufacturing costs. Furthermore, in the structure shown in Figures 17 and 18, an O-ring 97 is placed in an outer circumferential groove 96 provided on the outer circumferential surface of the clinching nut 95, and this O-ring 97 cannot be elastically deformed while being strongly pressed against the outer circumferential surface of the clinching nut 95 and the opening end face of the through-hole 94 of the outer case 93, resulting in the problem that a strong, tightly sealed seal cannot be achieved. The present invention was developed to solve these problems.

[0011] A battery pack according to one embodiment of the present invention includes a battery assembly including a plurality of battery cells, an outer case housing the battery assembly, an external output terminal positioned outside the outer case, and an output bus bar having the external output terminal fixed to a first end thereof and an output terminal of the battery assembly connected to a second end thereof. The external output terminal is formed of a clinching member having a cylindrical outer shape, and the output bus bar has a connecting port opened at the first end thereof, with a fixed end of the clinching member press-fitted into the connecting port, thereby fixing the clinching member in a vertical position, and the fixed end side of the clinching member is closed. The outer case has a surface plate that serves as a fixed portion to which the external output terminal is fixed, and a terminal insertion port through which the clinching member passes is opened in the fixed portion, and at least one of the opposing opening edges of the connecting port and the terminal insertion port is provided with a chamfered portion along the opening edge. Furthermore, an annular rubber-like elastic body through which the clinching member is inserted is disposed at the border of the opening edge of the connection port of the output bus bar, at the boundary with the clinching member. With the clinching member inserted into the terminal insertion port and the output bus bar fixed to the fixed portion, a seal is formed between the opening edge of the connection port, the opening edge of the terminal insertion port, and the outer peripheral surface of the clinching member via the elastically deformable rubber-like elastic body, thereby fixing the external output terminal to the exterior case in a waterproof structure.

[0012] The above configuration has the advantage that the output bus bar with the clinching member fixed thereto can be fixed to the exterior case with simple processing using a general-purpose clinching member without any special processing of the clinching member. In particular, the above structure provides a chamfered portion on at least one of the opening edges of the connecting port of the output bus bar and the opening edge of the terminal insertion port of the fixed portion. This allows the annular rubber-like elastic body sandwiched between the opening edges of the connecting port and the opening edge of the terminal insertion port to be positioned and pressed against the outer surface of the clinching member along the chamfered portion, thereby creating a reliable seal with the rubber-like elastic body. Therefore, the above configuration has the advantage that a reliable waterproof structure can be achieved while reducing manufacturing costs with a simple and easy structure.

[0013] In a battery pack according to another embodiment of the present invention, the clinching member is a nut member having a closed bottom and a fixed end, and the female thread portion of the nut member serves as an external connection portion for the external output terminal.

[0014] According to the above configuration, the clinching member is a blind-type nut member with a closed bottom and a fixed end, and the female screw portion of the nut member is a female terminal that serves as the external connection portion of the external output terminal, so that external connection can be made simply and easily by connecting the connection terminal via a bolt or the like having a male screw portion.

[0015] In a battery pack according to another embodiment of the present invention, the clinching member is a nut member with an open fixed end, and a bolt member is screwed into the nut member from the fixed end side to close the fixed end, and the male thread portion of the bolt member protrudes from the nut member, and the male thread portion of the bolt member serves as an external connection portion for an external output terminal.

[0016] According to the above configuration, the clinching member is a through-type nut member with an open fixed end, and a bolt member is screwed into this clinching member from the fixed end side to close the fixed end, and the male threaded portion of the screwed bolt member is made into a male terminal as the external connection portion of the external output terminal, so that external connection can be made simply and easily by connecting the connection terminal via a nut or the like having a female threaded portion.

[0017] In a battery pack according to another embodiment of the present invention, the rubber-like elastic material is an O-ring, and the width of the chamfered portion can be made larger than the radius of the O-ring in cross section, and the depth of the chamfered portion can be made smaller than the diameter of the O-ring in cross section.

[0018] According to the above configuration, the O-ring, which is a rubber-like elastic body, can be reliably elastically deformed while being guided into the chamfered portion, so that the clinching member and the output bus bar can be reliably fixed to the fixed portion while maintaining a waterproof structure.

[0019] In a battery pack according to another embodiment of the present invention, the rubber-like elastic material is an O-ring, and the area of ​​the chamfered region in the cross section of the chamfered portion can be smaller than the cross-sectional area of ​​the O-ring in the cross section.

[0020] According to the above configuration, the O-ring, which is a rubber-like elastic body, can be reliably elastically deformed and pressed while being guided into the chamfered portion, so that the external output terminal and the output bus bar can be fixed to the outer case while ensuring a waterproof structure.

[0021] In a battery pack according to another embodiment of the present invention, the exterior case may have a recess in the surface thereof in which the external output terminal is arranged, and the bottom surface of the recess may serve as the fixed portion.

[0022] According to the above configuration, the output bus bar is fixed to the bottom surface of the recess provided on the case surface of the outer case, and the connecting portion of the output bus bar is positioned inside the case surface, thereby protecting the connecting portion with the external output terminal.

[0023] In a battery pack according to another embodiment of the present invention, the depth of the recess can be made larger than the amount of protrusion of the external output terminal from the fixed portion.

[0024] According to the above configuration, the depth of the recess provided in the outer case is made greater than the amount of protrusion of the external output terminal protruding from the fixed portion, so that the external output terminal is disposed inside the recess without protruding from the surface of the case, thereby protecting the external output terminal and achieving a beautiful appearance.

[0025] (Embodiment 1) A battery pack according to one embodiment of the present invention is shown in Figures 1 to 10. In these figures, Figure 1 is a perspective view of the battery pack, Figure 2 is an exploded perspective view of the battery pack shown in Figure 1, Figure 3 is an exploded rear perspective view of the battery pack shown in Figure 2, seen from below, Figure 4 is an exploded perspective view of the battery pack, Figure 5 is a block diagram of the battery pack, Figure 6 is a plan view of the battery pack, Figures 7 and 8 are cross-sectional views taken along lines VII-VII and VIII-VIII in Figure 6, and Figure 9 is an exploded cross-sectional view of Figure 7. The battery pack shown in these figures includes a battery pack 2 including a plurality of battery cells 1, an exterior case 3 that houses the battery pack 2, an external output terminal 8 that is positioned to protrude from the exterior case 3, and an output bus bar 81 that has the external output terminal 8 fixed to a first end 81A and connects an output terminal 15 of the battery pack 2 to a second end 81B.

[0026] (Battery assembly 2) As shown in Figures 2 to 4, the battery pack 100 contains a plurality of battery cells 1 housed in an exterior case 3 as a battery assembly 2. The battery cells 1 are grouped in a predetermined arrangement to form battery blocks 10, and the battery blocks 10 are connected to form the battery assembly 2. The battery pack 100 shown in the figures is formed by stacking and connecting two battery blocks 10 in an upright position in the front-to-rear direction in the figures to form the battery assembly 2. The battery assembly 2 can connect the two battery blocks 10 stacked front-to-rear via a connecting member (not shown).

[0027] (Battery Cell 1) Battery cell 1 is a non-aqueous electrolyte secondary battery cell such as a lithium-ion battery. However, the present invention does not limit battery cell 1 to a lithium-ion battery; all currently used and future-developed secondary batteries, including other non-aqueous electrolyte secondary batteries and nickel-metal hydride batteries, can be used. Battery cell 1 in FIG. 4 is a cylindrical battery with electrode end faces at both ends. However, the battery pack of the present invention does not limit the battery to a cylindrical battery. This is because rechargeable prismatic batteries and other types of batteries can also be used for battery cell 1. A cylindrical battery contains electrodes and electrolyte in a cylindrical metal case. The metal case has a sealed structure in which a sealing plate is airtightly fixed to the opening of an outer can that closes the bottom. The outer can is manufactured by pressing a metal plate. The sealing plate is airtightly fixed to the periphery of the opening of the outer can by crimping via an insulating packing. A prismatic battery has insulated positive and negative electrode terminals attached to the sealing plate that closes the opening of the metal case.

[0028] (Battery Block 10) In the battery block 10, multiple battery cells 1 are arranged parallel to one another, with the electrode end faces of each battery cell 1 positioned on the same plane. In the battery block 10, multiple battery cells 1 are positioned in fixed positions using a plastic battery holder 12. The battery block 10 shown in Figure 4 houses 154 cylindrical batteries in the battery holders 12, with 11 battery cells 1 arranged in one row. In the battery block 10, each battery cell 1 is arranged parallel to the other, with the electrode end faces of the battery cells 1 positioned on the same plane, and lead plates 11 connected to the electrode end faces on the same plane.

[0029] (Lead Plates 11) The battery block 10 connects multiple battery cells 1 in parallel with each other using multiple lead plates 11. The lead plate 11 shown in FIG. 4 has a laminated structure consisting of connection lead plates 11A with connection portions that connect to the electrode end surfaces of multiple battery cells 1, and current-carrying lead plates 11B that reduce electrical resistance between battery cells 1 connected in parallel or in series. The connection lead plates 11A are connected to the electrode end surfaces using methods such as laser welding, spot welding, or ultrasonic welding. Furthermore, the battery block 10 connects the multiple battery cells 1 connected in parallel with each other in series via bus bars 14 located on the side of the battery holder 12. The battery block 10 shown in FIG. 4 has 154 battery cells 1 connected in 22 parallel and 7 series configurations. However, the number and connection state of the multiple battery cells in the battery block are not limited to these. The number and connection state of the connected battery cells can be varied in various ways.

[0030] (Battery Holder 12) The battery holder 12 in Figure 4 is designed to hold multiple battery cells 1 in fixed positions. The battery holder 12 in Figure 4 is molded from insulating plastic and has a cylindrical insertion section 13 for multiple battery cells 1 molded integrally therewith. The insertion section 13 holds the battery cells 1 set therein in fixed positions. The battery holder 12 in the figure uses cylindrical batteries, and the insertion section 13 is shaped to insert cylindrical batteries and hold them in fixed positions. The battery holder 12 in the figure arranges 154 battery cells 1 in 14 vertical rows, with 11 batteries per row in the left-right direction, and the battery cells 1 positioned above and below are arranged in the gaps between adjacent battery cells 1 on the left and right, similar to a rice bale stack.

[0031] As shown in Figure 4, the battery holder 12 is formed as a pair of separate cell holders 12A, 12B. Each of the cell holders 12A, 12B that make up the battery holder 12 has an insertion tube portion 13 into which a battery cell 1 is inserted in a parallel position. The insertion tube portion 13 is open at both ends, exposing the electrode end surfaces of the inserted cylindrical battery so that lead plates 11 can be connected to the electrode end surfaces. The insertion tube portions 13 of the cell holders 12A, 12B are long enough to insert approximately half of a battery cell 1. Each battery cell 1 is positioned in a fixed position in the battery holder 12 by inserting half into one cell holder 12A and the other half into the other cell holder 12B. The battery holder 12 constructed as described above has the advantage of being able to securely hold multiple battery cells 1 in fixed positions by inserting the battery cells 1 into the insertion tube portions 13 of the two separate cell holders 12A, 12B.

[0032] As shown in FIGS. 2 to 5 , the battery pack 2 described above has two battery blocks 10 connected in series, one behind the other. The two battery blocks 10 are connected in series via a connecting bus bar 16 located on the underside of the battery pack 2 in the figures. The connecting bus bar 16 is connected to the output lead 11b, which is one of the output lead portions 11a and 11b extending from the lead plates 11 connected to the positive and negative output sides of the battery cells 1 connected in series, extending to the lower side of the battery block 10, and is thus connected to the two battery blocks 10. Furthermore, the battery pack 2 has positive and negative output terminals 15 located on the upper side of the battery pack 2 in the figures. The positive and negative output terminals 15 are metal plates laminated on the output lead portion 11a extending to the upper side of the battery block. The positive and negative output terminals 15 of the battery pack 2 are connected to the external output terminals 8 via an output bus bar 81.

[0033] Furthermore, although not shown, the battery pack may also include a circuit board. The circuit board can be positioned in a fixed position in the exterior case via a board holder. The board holder can be positioned, for example, between the top surface of the battery pack and the exterior case, with the circuit board positioned inside. The circuit board can mount electronic components (not shown) that are connected to the battery cells and implement a battery cell protection circuit. The protection circuit can be a circuit that prevents overcharging or overdischarging of the battery cells, a circuit that prevents overcurrent, or a circuit that cuts off current when the temperature rises abnormally.

[0034] (External Case 3) The external case 3 has a rectangular box shape. This external case 3 is made of a material with excellent insulating properties, such as a resin such as polycarbonate or PC-ABS alloy. The external case 3 shown in FIGS. 2 and 3 is divided into two parts at the top and bottom midpoint: a main case 3A and a lid case 3B. The main case 3A and the lid case 3B are container-shaped, with main plates 41 and side plates 42 provided as peripheral walls 40 around end plates 43, forming a storage compartment 34 inside which the battery pack 2 can be stored. The main case 3A and the lid case 3B have different heights for the peripheral walls 40A, 40B connected to the end plates 43, making the main case 3A deeper than the lid case 3B. The main body case 3A and the lid case 3B are formed into a cylindrical shape by connecting the main surface plate 41 and the side plate 42 at both side edges, and an end surface plate 43 is connected to one end surface, and the other end surface is formed as an opening, forming a deep container shape.

[0035] The exterior case 3 shown in FIGS. 1 to 3 has multiple rows of grooves 44 formed on the surfaces of the main plate 41 and side plate 42, which make up the peripheral wall 40. The multiple grooves 44 are parallel to one another and extend in the height direction of the peripheral wall 40. The exterior case 3 shown in the figures has grooves 44 formed throughout the entire peripheral wall 40, reducing the overall weight of the exterior case 3 and increasing the surface area, thereby improving the heat dissipation characteristics of the exterior case 3. The main case 3A and the lid case 3B have multiple rows of grooves 44 formed from the end plate 43 toward the opening, but do not have grooves 44 on the edge of the opening; instead, flanges 45, 46 are formed along the edge of the opening. The main case 3A and the lid case 3B are connected to each other by connecting the opposing flanges 45, 46 via set screws 18. As shown in FIG. 3, the cover case 3B has a flange portion 46 provided with an insertion hole 46a for inserting the set screw 18, and the main body case 3A has a flange portion 45 serving as a boss into which the set screw 18 is screwed.

[0036] Furthermore, the main case 3A and the lid case 3B are connected at the opposing opening edges via a packing member 19 to provide a waterproof structure. The packing member 19 shown in Fig. 2 is a rubber packing having a predetermined thickness and a generally rectangular shape in plan view that fits along the opening end surfaces of the main case 3A and the lid case 3B, and is disposed along a vertical groove 47 provided in the opening end surface of the main case 3A. The main case 3A and the lid case 3B are connected by a set screw 18 at a position facing a groove 44 provided in the peripheral wall 40. Therefore, the packing member 19 shown in Fig. 2 has a U-shaped detour portion 19A on the inside at a position facing the groove 44, i.e., at the position where the set screw 18 is inserted. This allows the set screw 18 to be threaded on the outside of the packing member 19, preventing water from entering the screwed portion. The main case 3A and the lid case 3B are connected in a watertight structure by placing a packing member 19 in a vertical groove 47 on the open end face of the main case 3A and sandwiching the packing member 19 on the open end face of the lid case 3B, and by threading a setscrew 18 inserted into an insertion hole 46a in a flange portion 46 of the lid case 3B into the flange portion 45 of the main case 3A. A groove 44 with a short overall length formed in the lid case 3B also serves as a tool gap to guide a screwdriver when screwing in the setscrew 18.

[0037] (Recess 20) Furthermore, the exterior case 3 has exposed external output terminals 8 for outputting the positive and negative outputs of the built-in battery pack 2 to the outside. The exterior case 3 shown in FIG. 1 has the external output terminals 8 exposed on the top surface of the lid case 3B. The exterior case 3 has a recess 20 recessed inward from the case surface, and the external output terminals 8 are disposed inside this recess 20. As shown in FIGS. 1, 6, and 7, the recess 20 has a rectangular prism shape and a depth (h) sufficient to completely accommodate the external output terminals 8 protruding from the bottom surface. That is, the recess 20 is formed so that its depth (h) is greater than the amount of protrusion of the external output terminals 8 protruding from the bottom surface. This structure allows the external output terminals 8 to protrude from the case surface, resulting in a neat and beautiful appearance. Furthermore, storing the external output terminals 8 inside the recess 20 also has the advantage of protecting the external output terminals 8. However, it is not necessary to provide a recess on the surface of the outer case and place the external output terminal in this recess; the external output terminal can also be fixed to the surface plate that forms the surface of the case. The external output terminal 8 is fixed to the outer case 3 in a waterproof structure. The waterproof structure of this part will be described in detail below.

[0038] (Fixed Portion 21) In the outer case 3, a portion of the surface plate serves as the fixed portion 21 to which the external output terminal 8 is fixed. In the outer case 3 shown in Figures 7 to 9, the bottom surface of the recess 20 serves as the fixed portion 21 to which the external output terminal 8 is fixed. The fixed portion 21 is provided with a terminal insertion opening 22 through which the cylindrical clinching member 80, which is the external output terminal 8, is inserted. The terminal insertion opening 22 has a circular shape that conforms to the outer shape of the clinching member 80, and the inner diameter of the terminal insertion opening 22 is approximately equal to or slightly larger than the outer diameter of the clinching member 80. However, if the inner diameter of the terminal insertion opening 22 is too large, the gap between the opening edge of the terminal insertion opening 22 and the outer peripheral surface of the clinching member 80 becomes large, making waterproofing difficult. Therefore, the gap between the opening edge of the terminal insertion opening 22 and the outer peripheral surface of the clinching member 80 is preferably 1 mm or less, and more preferably 0.1 mm or less.

[0039] Furthermore, the fixed portion 21 has female threaded holes 24 on its underside into which fixing screws 26 that pass through the output bus bar 81 are screwed in order to fix the output bus bar 81. The female threaded holes 24 are formed deep by providing protrusions 25 that protrude from the upper surface of the fixed portion 21 so that the fixing screws 26 can be screwed deep into the fixed portion 21 without penetrating the fixed portion 21 and tightened. The female threaded holes 24 are provided at four locations around the terminal insertion opening 22, at equal intervals.

[0040] (External Output Terminal 8) The external output terminal 8 is composed of a clinching member 80 having a cylindrical outer shape. In this specification, the clinching member 80 refers to a member that is fixed by press-fitting one end into a through-hole formed in a metal plate, and examples include nut members called clinching nuts and clinching spacers. However, the present invention does not specify the clinching member 80 as described above, and other members that can be press-fitted to the output bus bar 81 for fixation can be used. The shape and fixing method of clinching members vary depending on the manufacturer, but in the present invention, regardless of these specifications, a commonly used clinching member is used for the external output terminal and fixed to the exterior case in a waterproof structure.

[0041] The cylindrical clinching member 80 is fixed in a vertical position to a connecting port 82 opened in the output bus bar 81. Furthermore, the clinching member 80 has a fixed end 80x fixed to the output bus bar 81 closed. The clinching member 80 shown in the figure is a nut member having a cylindrical outer shape, and is a bottomed nut member 80A that closes the fixed end 80x fixed to the output bus bar 81. For example, a blind-type clinching nut can be used as such a clinching member. The clinching member 80 is made of stainless steel, for example, SUS304. However, the clinching member may be made of a metal other than stainless steel. The metal clinching member 80 is press-fitted and fixed into the connecting port 82 opened in the metal output bus bar 81. In the external output terminal 8 having the above structure, the clinching member 80 is a bottomed nut member 80A with a closed fixed end 80x, and the female thread portion 80a of the nut member 80A serves as the external connection portion of the external output terminal 8. The external output terminal 8 having this shape serves as a female terminal to which an external connection line is connected via a bolt or the like having a male thread portion.

[0042] (Output Bus Bar 81) As shown in FIG. 7 , the output bus bar 81 is disposed inside the exterior case 3 and connects the output terminal 15 of the battery pack 2 to the external output terminal 8. The output bus bar 81 is a conductive metal plate having a predetermined thickness, for example, 1 to 2 mm. The external output terminal 8 is fixed to one end, a first end 81A, and the other end, a second end 81B, is connected to the output terminal 15 of the battery pack 2. For example, a nickel-plated aluminum plate or copper plate can be used as this metal plate. The output bus bar 81 shown in FIGS. 7 and 10 has an overall crank-like shape, with the first end 81A and the second end 81B bent in opposite directions relative to an intermediate portion 81C. This output bus bar 81 has the advantage that the first end 81A and the second end 81B, which are bent in opposite directions, are connected via the intermediate portion 81C, allowing the first end 81A and the second end 81B to be connected while being spaced apart vertically. Furthermore, the output bus bar 81 shown in the figure has a U-shaped bend in the middle section 81C to form an elastically deforming section 86. This elastically deforming section 86 has the advantage of being able to absorb, by elastic deformation, any tolerance or misalignment between the first end 81A fixed to the inner surface of the lid case 3B and the second end 81B connected to the output terminal 15 of the battery pack 2. However, the elastically deforming section may have a structure other than the U-shaped bend.

[0043] As shown in FIGS. 7 to 9 , the output bus bar 81 has a first end 81A to which the clinching member 80 is fixed, and a connecting port 82 for press-fitting the clinching member 80. The connecting port 82 has an inner diameter large enough to press-fit the fixed end 80x of the clinching member 80. Furthermore, the output bus bar 81 shown in FIGS. 10 to 13 has a chamfered portion 83 formed by chamfering the opening edge of the connecting port 82 along the opening edge on the surface facing the fixed portion 21. The chamfered portion 83 is cut out to provide an inclined surface 83A, and the chamfered area (shown by gray hatching in FIG. 11 ) has a substantially triangular cross-sectional shape. As shown in FIGS. 11 and 12 , the chamfered portion 83 formed on the opening edge of the connecting port 82 serves to position the annular rubber-like elastic body 70 sandwiched between the output bus bar 81 and the fixed portion 21. In this way, the structure in which a chamfered portion 83 is provided on the opening edge of the connecting port 82 opened in the output bus bar 81 is advantageous because it makes it possible to provide the chamfered portion 83, which serves as a positioning portion for the annular rubber-like elastic body 70, while removing metal burrs that occur on the opening edge during the process of opening the connecting port 82 in the metal plate.

[0044] 10 , the output bus bar 81 has insertion holes 84 formed around the connecting port 82, through which the fixing screws 26 pass to fix the first end 81A, to which the clinching member 80 is fixed, to the fixed portion 21. These insertion holes 84 are positioned opposite the female screw holes 24 formed in the fixed portion 21, and are provided at four locations around the connecting port 82 at equal intervals.

[0045] Furthermore, the output bus bar 81 has a connection hole 85 formed at a second end 81B, through which a connection bolt 27 is inserted for connection to the output terminal 15 of the battery pack 2. Fig. 7 shows the output bus bar 81 connected to the negative output terminal 15 of the battery pack 2, and this output bus bar 81 is connected to the output terminal 15 of the battery pack 2 via a current interruption element 17. As shown in Fig. 10, the connection hole 85 is formed as an elongated hole to allow for misalignment of the connection portion.

[0046] (Rubber-like elastic body 70) In order to fix the output bus bar 81, to which the clinching member 80 is fixed, to the fixed portion 21 in a watertight structure, an annular rubber-like elastic body 70 is arranged along the outer circumferential surface of the clinching member 80 between the output bus bar 81 and the fixed portion 21. As such a rubber-like elastic body 70, for example, an O-ring 71 made of silicone rubber or nitrile rubber can be used. As shown in Fig. 12 , when the output bus bar 81 is fixed to the fixed portion 21 while being arranged outside the clinching member 80, the rubber-like elastic body 70, which is the O-ring 71, is sandwiched between the output bus bar 81 and the fixed portion 21 and elastically deforms, thereby sealing the clinching member 80 against the terminal insertion opening 22 of the fixed portion 21 in a watertight structure.

[0047] At this time, the O-ring 71 is positioned by the chamfered portion 83 provided on the edge of the opening of the connecting port 82 of the output bus bar 81 and, while placed in a fixed position, is pressed against the edge of the opening of the terminal insertion port 22 of the fixed part 21 and elastically deformed. In this way, the O-ring 71 placed on the chamfered portion 83 of the connecting port 82 is crushed along the inclined surface 83A of the chamfered portion 83 and pressed toward the outer surface of the clinching member 80, thereby achieving an ideal seal. This is because when the O-ring 71 pressed by the fixed part 21 presses against the inclined surface 83A of the chamfered portion 83, the O-ring 71 receives a reaction force from the inclined surface 83A, which acts to press the outer surface of the clinching member 80 inward. In this way, the rubber-like elastic body 70, which is the O-ring 71, elastically deforms when pressed against the opening edge of the terminal insertion port 22 of the fixed part 21, the inclined surface 83A of the chamfered part 83, and the outer surface of the clinching member 80, thereby ideally sealing these parts and connecting them in a watertight structure.

[0048] As described above, in order to ideally elastically deform the O-ring 71 to achieve a seal, the width (w) of the chamfered portion 83 is preferably greater than the radius (r) of the cross section of the O-ring 71, and the depth (d) is preferably less than the diameter (2r) of the cross section of the O-ring 71. For example, the width (w) of the chamfered portion 83 can be r≦w≦2r, and the depth (d) can be r≦d≦2r. By shaping the chamfered portion 83 as described above, the O-ring 71, which is pressed against the opening edge of the terminal insertion port 22 of the fixed portion 21, can be reliably guided and positioned inside the chamfered portion 83, while also being appropriately elastically deformed along the chamfered portion 83, thereby reliably pressing against the outer peripheral surface of the clinching member 80.

[0049] The chamfered surface of the chamfered portion 83 formed as described above can be an inclined surface 83A. However, the chamfered surface of the chamfered portion may also be a curved surface, such as a convex or concave surface. Furthermore, as shown in the enlarged cross-sectional view of FIG. 11 , the area of ​​the chamfered region (shown by gray hatching in the drawing) in the cross section of the chamfered portion 83 is set to be smaller than the cross-sectional area of ​​the O-ring 71 in the non-elastically deformed cross section. This allows the O-ring 71, which is pressed against the chamfered portion 83 of the output bus bar 81, the outer peripheral surface of the clinching member 80, and the opening edge of the terminal insertion port 22 of the fixed portion 21, to elastically deform while pressed against the respective contact surfaces, thereby reliably sealing the respective contact portions.

[0050] As shown in Fig. 11 , the O-ring 71 to be placed in the chamfered portion 83 of the connecting port 82 can be placed in the chamfered portion 83 by inserting the clinching member 80 into the clinching member 80 after the clinching member 80 is fixed to the connecting port 82 of the output bus bar 81. However, as shown in Fig. 13 , the O-ring can also be placed in the chamfered portion 83 in the process of press-fitting the clinching member 80 into the connecting port 82 of the output bus bar 81. Fig. 13 shows the process of placing the O-ring 71 in the chamfered portion 83 with the output bus bar 81 placed on a support base 78, which is a jig, and then inserting the clinching member 80 inside the O-ring 71 and pressing it with a press part 79 to press-fit the clinching member 80 into the connecting port 82. According to this method, in the process of press-fitting the clinching member 80 into the connecting port 82, the O-ring 71, which has been placed in advance on the chamfered portion 83, can be sandwiched between the outer circumferential surface of the clinching member 80 and the inclined surface 83A of the chamfered portion 83 and placed in a fixed position, with the O-ring 71 being wrapped around the clinching member 80. With this output bus bar 81, the O-ring is also fixed in a fixed position when the clinching member 80 is press-fitted and fixed in the connecting port 82. Note that, although the illustrated example uses an O-ring 71 as the annular rubber-like elastic body 70, it is not limited to an O-ring, and any rubber-like elastic body having a similar cross-sectional shape, such as a triangular or polygonal cross-section, that is slightly larger than the cross-sectional shape of the chamfered portion 83 can also be used.

[0051] The external output terminals 8 of the battery pack 100 are fixed to the exterior case 3 in a waterproof structure by the following steps: (1) A connecting port 82 is opened at a predetermined position on the first end 81A of the output bus bar 81. The connecting port is opened by punching or the like. (2) The edge of the opening of the connecting port 82 opened in the output bus bar 81 is chamfered to provide a chamfered portion 83. This step can also serve as a step for removing metal burrs that may have occurred on the opening edge when the connecting port 82 was opened. (3) A clinching member 80 is press-fitted into the connecting port 82 of the output bus bar 81 to fix it. The clinching member 80 is fixed in a vertical position relative to the output bus bar 81. In this step, an O-ring 71 can also be fixed in a predetermined position at the chamfered portion 83, as shown in FIG. 13 . (4) As shown in FIG. 9 , the O-ring 71 is inserted into the clinching member 80 fixed to the output bus bar 81 and placed in the chamfered portion 83. (5) Furthermore, as shown in FIG. 9 , while guiding the clinching member 80 into the terminal insertion opening 22 opened in the fixed portion 21 of the outer case 3, the output bus bar 81 is placed on the underside of the fixed portion 21. (6) The output bus bar 81 placed on the underside of the fixed portion 21 is fixed to the fixed portion 21 with the fixing screws 26. The fixing screws 26 pass through the insertion holes 84 of the output bus bar 81 and are threaded into the female threaded holes 24 of the fixed portion 21, thereby fixing the output bus bar 81 to the underside of the fixed portion 21. (7) In this state, as shown in FIG. 12 , the O-ring placed on the chamfered portion 83 is sandwiched and pressed between the output bus bar 81 and the fixed portion 21, which are relatively close to each other, thereby elastically deforming and sealing the chamfered portion 83 of the output bus bar 81, the opening edge of the terminal insertion opening 22 of the fixed portion 21, and the outer peripheral surface of the clinching member 80.

[0052] In this manner, the output bus bar 81 is fixed in a predetermined position inside the lid case 3B. The lid case 3B is then coupled to the main case 3A and secured with the set screws 18, after which the second end 81B of the output bus bar 81 is connected to the output terminal 15 of the battery pack 2. In the process of connecting the output bus bar 81 to the output terminal 15, as shown in FIG. 7 , the connection bolt 27 is inserted and screwed through a cylindrical opening 48 that is formed integrally with the end plate 43 of the lid case 3B and opens into the case surface. After the output bus bar 81 is connected to the output terminal 15 via the connection bolt 27, the opening of the cylindrical opening 48 is watertightly sealed with a sealing member 49.

[0053] The exterior case 3 shown in FIGS. 1, 2, and 6 has recesses 20 in two locations on the cover case 3B to expose the positive and negative external output terminals 8, where the positive and negative external output terminals 8 are located. The positive and negative external output terminals 8 are basically fixed using the same structure, but the clinching members 80 have different diameters for the positive and negative external output terminals 8. This allows the user to correctly connect the positive and negative external output terminals 8 without incorrectly connecting them. In the battery pack 100 shown in FIG. 6, the positive external output terminal 8 (shown in the lower left of FIG. 6 ) connected to the positive output terminal 15 of the assembled battery 2 is provided with a nut member having an inner diameter of 12 mm, and the negative external output terminal 8 (shown in the upper right of FIG. 6 ) connected to the negative output terminal 15 of the assembled battery 2 is provided with a nut member having an inner diameter of 8 mm.

[0054] Furthermore, a current interruption element 17 is connected between the negative external output terminal 8 and the output terminal 15 of the battery pack 2. The current interruption element 17 shown in Figures 2 and 7 is a fuse that melts to interrupt the current when an overcurrent flows through the battery pack 2. However, a circuit breaker or the like can also be used instead of a fuse. The current interruption element 17 in Figure 7 has lead portions 17B on both sides of an element body 17A. One lead portion 17B is connected to the second end 81B of the output bus bar 81 via a connecting bolt 27, and the other lead portion 17B is connected to the output terminal 15 of the battery pack 2 via the connecting bolt 27.

[0055] (Another Example of Waterproof Structure) In the above waterproof structure, the opening edge of the connecting port 82 in the output bus bar 81 is chamfered to provide the chamfered portion 83. However, the chamfered portion can also be provided by chamfering the opening edge of the terminal insertion port in the fixed portion 21. This waterproof structure is shown in FIGS. 14 and 15. In the waterproof structure shown in these figures, the opening edge of the connecting port 82 in the output bus bar 81 to which the clinching member 80 is fixed is not chamfered, but a chamfered portion is provided on the opening edge of the terminal insertion port 22 in the fixed portion 21. The fixed portion 21 shown in the figures has a chamfered portion 23 formed by chamfering the opening edge of the terminal insertion port 22 along the opening edge on the surface facing the output bus bar 81. The chamfered portion 23 is cut out to provide an inclined surface 23A, and its dimensions and shape can be similar to those of the chamfered portion 83 provided in the output bus bar described above.

[0056] In the above waterproof structure, the O-ring 71 is positioned by the chamfered portion 23 provided on the opening edge of the terminal insertion port 22 of the fixed portion 21 and is pressed against the output bus bar 81 and elastically deformed when placed in a fixed position. In this way, the O-ring 71 placed on the chamfered portion 23 of the terminal insertion port 22 is crushed along the inclined surface 23A of the chamfered portion 23 and pressed against the outer circumferential surface of the clinching member 80, thereby achieving an ideal seal. This is because when the O-ring 71 pressed by the output bus bar 81 presses against the inclined surface 23A of the chamfered portion 23, the O-ring 71 receives a reaction force from the inclined surface 23A, which acts to press the outer circumferential surface of the clinching member 80 inward. In this waterproof structure, the rubber-like elastic body 70, which is the O-ring 71, elastically deforms when pressed against the chamfered portion 23 provided on the opening edge of the terminal insertion port 22 of the fixed portion 21, the output bus bar 81, and the outer circumferential surface of the clinching member 80, thereby ideally sealing these components and connecting them in a watertight structure. Furthermore, in the battery pack of the present invention, chamfered portions can be provided on both the output bus bar and the fixed portion.

[0057] (Another Example of External Output Terminal) The above-described external output terminal 8 is configured with a clinching member 80, which is a bottomed nut member 80A, and a female screw portion 80a provided on the inner surface of the nut member 80A serves as the external connection portion of the external output terminal 8. Furthermore, in the present invention, the external output terminal may have a structure shown in FIG.

[0058] 16 , the clinching member 80 is a nut member 80B with an open fixed end 80x, and a bolt member 87 is screwed into this nut member 80B from the side of the fixed end 80x to close the fixed end 80x with the head of the bolt member 87, with the male thread portion 87a of the bolt member 87 protruding from the nut member 80B and serving as an external connection portion. In the external output terminal 8 with this structure, the clinching member 80 is a through-type nut member 80B with an open fixed end 80x, and the bolt member 87 is screwed into this nut member 80B from the side of the fixed end 80x to serve as the external connection portion of the external output terminal 8. The external output terminal 8 with this shape serves as a male terminal, and a line to be connected to an external connection terminal is connected via a nut or the like with a female thread portion.

[0059] In consideration of the load on the O-ring, the process of screwing bolt member 87 into nut member 80B with an open fixed end 80x from the fixed end 80x side is preferably performed before fixing nut member 80B to fixed portion 21. Furthermore, in the process of screwing bolt member 87 into nut member 80B to fix it, a sealing material such as sealing tape is preferably used to reliably seal open fixed end 80x of nut member 80B with bolt member 87. In the structure shown in Figure 16, chamfered portion 83 for positioning O-ring 71 is provided on the edge of the opening of connection port 82 of output bus bar 81, but as described above, it may also be provided on the edge of the opening of terminal insertion port 22 of fixed portion 21.

[0060] The present invention is a battery pack used as a power source for electric vehicles or electric heavy machinery, forklifts, etc., and is particularly effective for battery packs that house a large number of battery cells in an exterior case.

[0061] DESCRIPTION OF SYMBOLS 100...Battery pack 1...Battery cell 2...Battery assembly 3...External case 3A...Main body case 3B...Cover case 8...External output terminal 10...Battery block 11...Lead plate 11A...Connection lead plate 11B...Current-carrying lead plate 11a...Output lead portion 11b...Output lead portion 12...Battery holder 12A, 12B...Cell holder 13...Insertion tube portion 14...Bus bar 15...Output terminal 16...Connecting bus bar 17...Current interrupting element 17A...Element body 17B...Lead portion 18...Set screw 19...Packing member 19A...Detour portion 20...Recess 21...Fixed portion 22...Terminal insertion port 23...Chamfered portion 23A...Inclined surface 24...Female threaded hole 25...Protrusion 26...Fixing screw 27...Connecting bolt 34...Storage portion 40, 40A, 40B... Peripheral wall 41... Main surface plate 42... Side plate 43... End surface plate 44... Groove portion 45... Flange portion 46... Flange portion 46a... Insertion hole 47... Vertical groove 48... Opening cylindrical portion 49... Closing member 70... Rubber-like elastic body 71... O-ring 78... Support base 79... Press portion 80... Clinching member 80A, 80B... Nut member 80a... Female thread portion 81... Output bus bar 81A... First end portion 81B... Second end portion 82... Connection port 83... Chamfered portion 83A... Inclined surface 84... Insertion hole 85... Connection hole 86... Elastic deformation portion 87... Bolt member 87a... Male thread portion 91... Output bus bar 92... Connection port 93... Outer case 94... Through hole 95... Clinching nut 96...Outer circumferential groove 97...O-ring 98...Fixing screw

Claims

1. A battery pack comprising: an assembled battery having a plurality of battery cells; an exterior case housing the assembled battery; an external output terminal arranged to protrude from the exterior case; and an output bus bar having a first end to which the external output terminal is fixed and a second end to which an output terminal of the assembled battery is connected, wherein the external output terminal is formed of a clinching member having a cylindrical outer shape, the clinching member is fixed vertically by a fixed end of the output bus bar being press-fitted into a connecting port opened at the first end, and the fixed end of the clinching member is closed, the exterior case has a part of a surface plate as a fixed portion to which the external output terminal is fixed, and a terminal insertion port through which the clinching member passes is opened in the fixed portion, and at least one of the opening edge of the connecting port and the opening edge of the terminal insertion port facing each other is provided with a chamfered portion along the opening edge, Furthermore, a ring-shaped rubber-like elastic body through which the clinching member is inserted is disposed at the opening edge of the connecting port of the output bus bar, at the boundary with the clinching member, and when the clinching member is inserted into the terminal insertion port and the output bus bar is fixed to the fixed portion, a seal is formed between the opening edge of the connecting port, the opening edge of the terminal insertion port, and the outer peripheral surface of the clinching member via the rubber-like elastic body, which elastically deforms, thereby fixing the external output terminal to the outer case in a waterproof structure.

2. A battery pack as described in claim 1, wherein the clinching member is a bottomed nut member whose fixed end is closed, and the female threaded portion of the bottomed nut member serves as the external connection portion of the external output terminal.

3. A battery pack as described in claim 1, wherein the clinching member is a nut member with an open fixed end, a bolt member is screwed into the open nut member from the side of the fixed end to close the fixed end, and the male thread portion of the bolt member is caused to protrude from the open nut member, and the male thread portion of the bolt member serves as an external connection portion for the external output terminal.

4. A battery pack as claimed in any one of claims 1 to 3, wherein the rubber-like elastic body is an O-ring, the width of the chamfered portion is greater than the radius of the O-ring in cross section, and the depth of the chamfered portion is smaller than the diameter of the O-ring in cross section.

5. A battery pack as claimed in any one of claims 1 to 3, wherein the rubber-like elastic body is an O-ring, and the area of ​​the chamfered region in the cross section of the chamfered portion is smaller than the cross-sectional area of ​​the O-ring in the cross section.

6. A battery pack as described in claim 1, wherein the exterior case has a recess in a surface thereof in which the external output terminal is disposed, and the bottom surface of the recess serves as the fixed portion.

7. A battery pack as described in claim 6, wherein the depth of the recess is greater than the amount of protrusion of the external output terminal from the fixed portion.

8. A battery pack comprising: an assembled battery having a plurality of battery cells; an exterior case housing the assembled battery; an external output terminal arranged to protrude from the exterior case; and an output bus bar having a first end to which the external output terminal is fixed and a second end to which an output terminal of the assembled battery is connected, wherein the external output terminal is a clinching member having a cylindrical outer shape, the output bus bar has a fixed end which is press-fitted into a connecting port which opens into the first end and is fixed vertically by the clinching member, and the fixed end of the clinching member is closed, a part of the surface of the exterior case serves as a fixed portion to which the external output terminal is fixed, and a terminal insertion port which penetrates the clinching member opens into the fixed portion, and at least one of the opening edges of the connecting port and the opening edges of the terminal insertion port which face each other is provided with a chamfered portion along the opening edge, Furthermore, a ring-shaped rubber-like elastic body through which the clinching member is inserted is disposed near the boundary between the opening edge of the connecting port of the output bus bar, the opening edge of the terminal insertion port, and the clinching member, and when the clinching member is inserted into the terminal insertion port and the output bus bar is fixed to the fixed portion, the battery pack is sealed via the rubber-like elastic body which elastically deforms between the opening edge of the connecting port, the opening edge of the terminal insertion port, and the outer peripheral surface of the clinching member.

9. A battery pack as described in claim 8, wherein the clinching member is a bottomed nut with the fixed end closed, and the female thread of the bottomed nut serves as a female terminal of the external output terminal.

10. A battery pack as described in claim 8, wherein the clinching member is a nut with an open fixed end, the fixed end being closed by a head of a bolt fastened to the open nut, the male thread of the bolt protruding from the open nut member, and the male thread of the bolt serving as a male terminal of the external output terminal.

11. A battery pack as described in any one of claims 8 to 10, wherein the cross-sectional shape of the chamfered area in the cross-section of the chamfered portion is approximately triangular, the rubber-like elastic body is an O-ring, and in the cross-section, the width of the chamfered portion is greater than the radius of the O-ring in the cross-section and the depth of the chamfered portion is smaller than the diameter of the O-ring in the cross-section.

12. A battery pack as claimed in any one of claims 8 to 11, wherein the rubber-like elastic body is an O-ring, and the cross-sectional area of ​​the O-ring in a transverse cross section is greater than the area of ​​the chamfered region in the transverse cross section of the chamfered portion.

13. A battery pack as described in claim 8, wherein the exterior case has a recess on the surface of the case, the external output terminal is disposed in the recess, and the fixed portion is the bottom surface of the recess.

14. A battery pack as described in claim 13, wherein the depth of the recess is greater than the amount of protrusion of the external output terminal from the fixed portion.