Battery pack

Abstract

The present invention provides a battery pack capable of suppressing a phenomenon in which a gas venting tube sinks into a gas passage cover and damages safety valves, even if an external force is applied due to collision of the gas venting tube with a worktable or the ground.　Provided is a battery pack in which are stacked a plurality of unit cells each having a safety valve. The battery pack includes: a gas passage cover which is formed from a synthetic resin, disposed facing the safety valves, and in which is formed a gas passage to carry gas vented from the safety valves of the plurality of unit cells; and a gas venting tube integrally formed with the gas passage cover and extending in a direction away from the unit cells to dispose of gas in the gas passage to the outside. The gas venting tube is structured so as not to sink into the gas passage cover when an external force is applied, or the gas venting tube is set to a length that does not reach the safety valves even if the gas venting tube sinks into the gas passage cover when an external force is applied.

Description

battery pack

[0001] The present invention relates to a battery pack configured by connecting a plurality of unit cells, and to a battery pack in which the unit cells are provided with safety valves (gas release valves).

[0002] For example, electrolyte batteries (hereinafter referred to as lithium ion batteries) including a positive electrode layer capable of absorbing / desorbing lithium ions and a negative electrode layer are widely used as high-energy density batteries in various fields such as electric vehicles, hybrid vehicles, and power storage devices. Known lithium ion batteries include those that use a liquid electrolyte and those that use a solid electrolyte.

[0003] A secondary battery using a lithium-ion battery is composed of a battery pack consisting of multiple lithium-ion cells. This battery pack can generate a large amount of power by electrically connecting the cells with electrode members (hereinafter referred to as bus bars) made of conductive metals such as aluminum, copper, and iron.

[0004] A lithium-ion battery includes, for example, a wound electrode assembly and a battery can that houses the wound electrode assembly. The battery can includes an exterior body that is a box-shaped container with an opening on one side, and a battery lid that closes the opening of the exterior body. Furthermore, in this type of lithium-ion battery, a safety valve is provided on the battery lid to improve safety.

[0005] This safety valve is a battery component designed to open at a predetermined pressure to discharge the gas inside the battery can when gas is suddenly generated inside the battery can.

[0006] For example, the battery pack described in JP 2007-73298 A (Patent Document 1) includes a gas exhaust passage through which gas discharged from the cells flows, and a gas exhaust pipe for discharging the gas that has flowed through the gas exhaust passage to the outside. Furthermore, the gas exhaust pipe is connected to, for example, a gas exhaust hose, and is configured to exhaust the gas discharged from the cells to any desired location.

[0007] JP 2007-73298 A

[0008] The gas exhaust pipe is located on the opposite side of the bus bar from the cell side (equivalent to the upper side if the cell side is considered the lower side), that is, formed in a gas passage cover located above the bus bar. The gas passage cover is equipped with a gas exhaust passage through which gas flows and the gas exhaust pipe. The gas exhaust passage is shaped to face the safety valve and is configured to guide gas exhausted from the safety valve to the gas exhaust pipe.

[0009] Furthermore, if the battery pack is inadvertently dropped while being transported, for example, it is required to prevent the gas exhaust pipe from affecting surrounding components.

[0010] An object of the present invention is to provide a highly safe battery pack that minimizes the impact of a gas exhaust pipe on surrounding components even if the gas exhaust pipe collides with a workbench or the ground and an external force is applied.

[0011] The present invention provides a battery pack in which a plurality of cells each having a safety valve are stacked, the battery pack comprising: a gas passage cover made of synthetic resin, disposed opposite the safety valve, and having a gas exhaust passage formed therein for flowing gas exhausted from the safety valves of the plurality of cells; and a gas exhaust pipe formed integrally with the gas passage cover, extending in a direction away from the cells, for discharging gas in the gas exhaust passage to the outside, the gas exhaust pipe having a collapse prevention function portion formed therein that prevents the gas exhaust pipe from collapsing inside the gas passage cover when an external force is applied.

[0012] The present invention also provides a battery pack in which a plurality of cells each having a safety valve are stacked, the battery pack comprising: a gas passage cover made of synthetic resin, disposed opposite the safety valve, and having formed therein a gas exhaust passage for passing gas exhausted from the safety valves of the plurality of cells; and a gas exhaust pipe formed integrally with the gas passage cover, extending in a direction away from the cells, for discharging gas in the gas exhaust passage to the outside, the gas exhaust pipe being set to a length such that the gas exhaust pipe will not reach the safety valve even if it collapses inside the gas passage cover when an external force is applied.

[0013] According to the present invention, it is possible to provide a highly safe battery pack in which the effects on surrounding components are suppressed even if the gas exhaust pipe collides with a workbench or the ground and an external force is applied.

[0014] 1 is an external perspective view of a battery pack according to an embodiment of the present invention; FIG. 2 is a top view of the battery pack of FIG. 1 with a gas passage cover removed, as viewed from above; FIG. 3 is an external perspective view of the battery pack of FIG. 1 disassembled, with a plurality of cells and a holding unit, with some of the components of the holding unit disassembled in the width direction Y and the stacking direction X, as viewed from obliquely above; FIG. 4 is an external perspective view of the battery pack of FIG. 1 with a first side plate, a second side plate, and fastening bolts removed, with the components of the cells and the holding unit disassembled in the stacking direction X, as viewed from obliquely above; FIG. 5 is an external perspective view of a bus bar unit, a voltage detection unit, and a temperature measurement unit, as viewed from obliquely above; FIG. 6 is an external perspective view of a gas passage cover and a gas discharge pipe for explaining problems with a conventional gas passage cover and gas discharge pipe; FIG. 7 is a longitudinal sectional view of a connection portion between a gas passage cover and a gas discharge pipe according to a first embodiment of the present invention; FIG. 8 is an external perspective view of a connection portion between a gas passage cover and a gas discharge pipe according to a second embodiment of the present invention; FIG. 9 is a side view of the gas discharge pipe shown in FIG. 1; FIG. 10 is a longitudinal sectional view of the connection portion between a gas passage cover and a gas discharge pipe shown in FIG. 8; FIG. 11 is a longitudinal sectional view of the gas discharge pipe shown in FIG. 8; Fig. 14 is a longitudinal sectional view of a gas exhaust pipe showing a modified example of the gas exhaust pipe shown in Fig. 8. Fig. 15 is a side view of a connection portion of a gas exhaust pipe according to a third embodiment of the present invention. Fig. 16 is a longitudinal sectional view of the gas exhaust pipe shown in Fig. 13. Fig. 17 is a longitudinal sectional view of a connection portion of a gas passage cover and a gas exhaust pipe according to a fourth embodiment of the present invention.

[0015] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiment, and various modifications and application examples within the technical concept of the present invention are also included within its scope.

[0016] In the drawings, the size and proportions of components may be exaggerated, and the same components are denoted by the same reference numerals in the drawings.

[0017] In each drawing, the stacking direction X, width direction Y, and height direction Z of the battery pack are indicated by arrows. However, in each drawing, the stacking direction X, width direction Y, and height direction Z of the battery pack indicate the relative positional relationship within the same drawing.

[0018] That is, when the battery pack 1 is rotated 180 degrees and placed with the top and bottom surfaces reversed, or when the battery pack 1 is rotated 90 degrees and placed with the top surface facing sideways, the stacking direction X, width direction Y, and height direction Z of the battery pack change.

[0019] First, the configuration of the battery pack 1 will be described with reference to FIGS.

[0020] Fig. 1 shows a battery pack according to an embodiment of the present invention, viewed from diagonally above. Fig. 2 shows the battery pack of Fig. 1 viewed from above, with the gas passage cover removed. Fig. 3 shows a plurality of cells and a holding unit, with some of the components of the holding unit disassembled in the width direction Y and the stacking direction X, viewed from diagonally above. Fig. 4 shows a battery pack and holding unit disassembled in the stacking direction X, with the first side plate, second side plate, and fastening bolts removed, viewed from diagonally above. Fig. 5 shows a bus bar unit, voltage detection unit, and temperature measurement unit viewed from diagonally above.

[0021] 1, the battery pack 1 is configured as a power source for operating, for example, an electric motor for propelling a vehicle. The battery pack 1 may also be configured as a power source for operating, for example, electrical equipment mounted on the vehicle.

[0022] 1 , the battery pack 1 includes a plurality of cells 100, a holding unit 200 that holds the plurality of cells 100, and a bus bar unit 300 that electrically connects the plurality of cells 100. The battery pack 1 also includes a voltage detection unit 400 that detects the voltage of the cells 100, and a temperature measurement unit 500 that measures the temperature of the cells 100. The components included in the battery pack 1 will be described below.

[0023] <Configuration of Cell 100> The cells 100 shown in Figs. 1 to 4 are stacked in a stacking direction X via a holding unit 200. As shown in Fig. 2, for example, 20 cells 100 are stacked. The cells 100 are, for example, lithium ion secondary batteries.

[0024] The cell 100 includes a current collector and an electrolyte. As shown in Fig. 4, the cell 100 includes a container 101, a lid 102, a positive electrode terminal 103, a negative electrode terminal 104, and a safety valve 105. The components included in the cell 100 will be described below.

[0025] The unit cell 100 is formed in a rectangular parallelepiped shape as shown in Fig. 4. A positive electrode terminal 103 and a negative electrode terminal 104 are provided on an upper surface 100a of the unit cell 100 along the stacking direction X.

[0026] The upper surface 100a corresponds to the upper surface of the cell 100 in Fig. 4. The upper surface 100a is formed in a rectangular shape. The length of the upper surface 100a along the width direction Y of the cell 100 is longer than the length of the upper surface 100a along the stacking direction X of the cell 100. The upper surface 100a faces the busbar unit 300 shown in Fig. 1.

[0027] Two side surfaces 100b along the stacking direction X of the battery 100 are perpendicular to and face the top surface 100a. The side surfaces 100b are formed in a rectangular shape. The length of the side surfaces 100b along the height direction Z of the battery 100 is longer than the length of the side surfaces 100b along the stacking direction X of the battery 100. Two main surfaces 100c facing the stacking direction X of the battery 100 are in contact with the cell spacers 202 of the holding unit 200, etc.

[0028] The current collector of the cell 100 corresponds to a charge / discharge element for inputting and outputting electric power. The current collector of the cell 100 is configured by winding or stacking a positive electrode and a negative electrode with a separator interposed therebetween. The container 101 contains the current collector and an electrolyte. The lid 102, together with the container 101, seals the current collector and the electrolyte.

[0029] The lid 102 is joined to the container 101. The positive electrode terminal 103 and the negative electrode terminal 104 relay input and output of electric power between the current collector and the electrical device. The positive electrode terminal 103 and the negative electrode terminal 104 are attached to the lid 102. The positive electrode terminal 103 of one cell 100 and the negative electrode terminal 104 of the other cell 100 that are adjacent along the stacking direction X face each other in the stacking direction X, as shown in FIG.

[0030] The safety valve 105 bursts outward from the cell 100 when the internal pressure of the cell 100 exceeds a predetermined value. The safety valve 105 is also called a burst valve. The safety valve 105 is provided on the lid 102, for example.

[0031] 1 to 4, the holding unit 200 holds a plurality of cells 100. As shown in FIG. 4, the holding unit 200 includes a first end spacer 201, a cell spacer 202, and a second end spacer 203.

[0032] The holding unit 200 also includes a first end block 211, a second end block 212, an insulating member 221, and an insert nut 222. As shown in Fig. 3, the holding unit 200 also includes a first side plate 231, a second side plate 232, and a fastening bolt 241. The components included in the holding unit 200 will be described below.

[0033] As shown in Fig. 4 , the first end spacer 201 is provided between the first end block 211 and the cell 100. The first end spacer 201 contacts the first cell 100 located at one end of the 20 stacked cells 100. This cell 100 corresponds to the cell 100 located at the left end in Fig. 2 . The first end spacer 201 insulates the first end block 211 from the cell 100.

[0034] The first end spacer 201 covers each side surface of the first end block 211 and the cell 100 along the width direction Y. The first end spacer 201 covers a portion of the side surface 100b along the stacking direction X of the cell 100. The thickness of the first end spacer 201 along the stacking direction X is sufficiently thinner than the thickness of the cell 100 along the stacking direction X. The first end spacer 201 is made of an insulating material.

[0035] As shown in FIG. 4 , the cell spacers 202 are provided between adjacent cells 100. The cell spacers 202 hold and insulate the adjacent cells 100. The cell spacers 202 cover the main surfaces 100c of the adjacent cells 100 along the width direction Y and a portion of the side surfaces 100b of the adjacent cells 100 along the stacking direction X. The thickness of the cell spacers 202 along the stacking direction X is sufficiently thinner than the thickness of the cells 100 along the stacking direction X. The cell spacers 202 are made of an insulating material.

[0036] As shown in Fig. 4 , the second end spacer 203 is provided between the cell 100 and the second end block 212. The second end spacer 203 contacts the twentieth cell 100 located at the other end of the stack of 20 cells 100. This cell 100 corresponds to the cell 100 located at the right end in Fig. 2 . The second end spacer 203 insulates the cell 100 from the second end block 212.

[0037] The second end spacer 203 covers each side surface of the first end block 211 and the cell 100 along the width direction Y. The second end spacer 203 covers a portion of the side surface 100b along the stacking direction X of the cell 100. The thickness of the second end spacer 203 along the stacking direction X is sufficiently thinner than the thickness of the cell 100 along the stacking direction X. The second end spacer 203 is formed from an insulating material.

[0038] 4 , the first end block 211 is stacked with the first cell 100 located at one end of the 20 stacked cells 100 via a first end spacer 201. The first end block 211 extends along a width direction Y that intersects with the stacking direction X of the cells 100.

[0039] The first end block 211 is adjacent to the cell 100 located at the end along the stacking direction X and supports the cell 100. The first end block 211 is formed in a rectangular parallelepiped shape extending in the width direction Y. Fastening bolts 241 are screwed into a plurality of screw holes 211m formed in the side surface of the first end block 211 along the width direction Y as shown in FIG. 3. The first end block 211 is fixed to the first side plate 231 by the fastening bolts 241, as shown in FIG. 1.

[0040] Similarly, the first end block 211 is fixed to the second side plate 232 by fastening bolts 241. The first end block 211 has insertion holes 211n formed therein for inserting bolts or the like for fastening the battery pack 1. The first end block 211 is made of, for example, metal or resin.

[0041] 4 , the second end block 212 is stacked with the twentieth cell 100 located on the other end side of the stacked 20 cells 100 via a second end spacer 203. The second end block 212 extends along the width direction Y of the cell 100.

[0042] The second end block 212 is adjacent to the cell 100 located at the end along the stacking direction X and supports the cell 100. The second end block 212 is formed in a rectangular parallelepiped shape extending in the width direction Y. Fastening bolts 241 are screwed into a plurality of screw holes formed in the side surface of the second end block 212 along the width direction Y as shown in FIG. 3. The second end block 212 is fixed to the first side plate 231 by the fastening bolts 241, as shown in FIG. 1.

[0043] Similarly, the second end block 212 is fixed to the second side plate 232 by fastening bolts 241. The second end block 212 is formed with insertion holes 212n for inserting bolts or the like for fastening the battery pack 1. The second end block 212 is formed of, for example, metal or resin.

[0044] 4, the insulating member 221 is inserted into the first end block 211. The insulating member 221 is also inserted into the second end block 212. The insulating member 221 is formed, for example, in a rectangular parallelepiped shape. The insulating member 221 is made of an insulating material.

[0045] The insulating member 221 may be configured as follows. That is, the insulating member 221 may be molded integrally with the first end spacer 201, or may be molded separately from the first end spacer 201 and then joined to the first end spacer 201. In such a case, the first end block 211 has a recess on the surface facing the first end spacer 201 that accommodates the insulating member 221 along the stacking direction X.

[0046] Similarly, the insulating member 221 may be molded integrally with the second end spacer 203, or may be molded separately from the second end spacer 203 and then joined to the second end spacer 203. In such a case, the second end block 212 has a recess on the surface facing the second end spacer 203 that accommodates the insulating member 221 along the stacking direction X.

[0047] 3, the insert nut 222 is embedded in a recess formed in the upper surface of the insulating member 221. A fastening bolt is anchored to the insert nut 222 via a bus bar that is electrically connected to an external control device, for example.

[0048] 1 , the first side plate 231 is arranged along the stacking direction X of the stacked plurality of unit cells 100 at one end in the width direction Y of the plurality of unit cells 100. The first side plate 231 holds the plurality of unit cells 100 along the stacking direction X. Both ends of the first side plate 231 extending along the stacking direction X are bent toward the width direction Y.

[0049] 3, the first side plate 231 has a plurality of insertion holes 231m formed on a side surface along the width direction Y, into which fastening bolts 241 are inserted. As shown in FIG. 1, the first side plate 231 is fixed to the first end block 211 and the second end block 212 by the fastening bolts 241.

[0050] 1 , the second side plate 232 is arranged along the stacking direction X of the stacked cells 100 at the other end of the cells 100 in the width direction Y. The second side plate 232 holds the cells 100 along the stacking direction X. Both ends of the second side plate 232 extending along the stacking direction X are bent toward the width direction Y.

[0051] 3, the second side plate 232 has a plurality of insertion holes 232m formed on a side surface along the width direction Y, into which fastening bolts 241 are inserted. As shown in FIG. 1, the second side plate 232 is fixed to the first end block 211 and the second end block 212 by the fastening bolts 241.

[0052] 2, the fastening bolts 241 fasten the first side plate 231 to the first end block 211, and the first side plate 231 to the second end block 212. Also, the fastening bolts 241 fasten the second side plate 232 to the first end block 211, and the second side plate 232 to the second end block 212, as shown in FIG.

[0053] <Configuration of Busbar Unit 300> The busbar unit 300 shown in Figures 1, 2, and 5 electrically connects a plurality of cells 100. As shown in Figure 5, the busbar unit 300 includes a first end busbar 301, a plurality of busbars 302, a second end busbar 303, and a busbar holder 311. The components included in the busbar unit 300 will be described below.

[0054] As shown in Fig. 2 , the first end bus bar 301 is joined to the positive electrode terminal 103 of the battery cell 100 that is closest to the first end block 211 among the 20 stacked battery cells 100. As shown in Fig. 5 , the first end bus bar 301 includes a plate-shaped first joint portion 301a, a plate-shaped second joint portion 301b, a curved connecting portion 301c, and an insertion hole 301d.

[0055] The first joint portion 301a is joined to a bus bar that is electrically connected to an external control device. The second joint portion 301b is joined to the positive electrode terminal 103 of the battery 100. The connecting portion 301c connects the first joint portion 301a and the second joint portion 301b. The insertion hole 301d is formed in the first joint portion 301a.

[0056] A fastening bolt is inserted into the insertion hole 301d. The first joint portion 301a and the bus bar that is electrically connected to an external control device are joined by the fastening bolt. The first end bus bar 301 is made of, for example, aluminum. When the first end bus bar 301 is made of a clad material, for example, the first joint portion 301a is made of copper and the second joint portion 301b is made of aluminum.

[0057] If the negative electrode terminal 104 of the battery cell 100 is configured such that copper is converted to aluminum, the first end bus bar 301 may be configured such that the first joint portion 301a and the second joint portion 301b are integrally formed from aluminum.

[0058] As shown in FIG. 2 , the bus bar 302 electrically connects one cell 100 to another cell 100 that are adjacent to each other along the stacking direction X. As shown in FIG. 2 , the bus bar 302 is joined to the positive electrode terminal 103 of one cell 100 that are adjacent to each other along the stacking direction X and the negative electrode terminal 104 of the other cell 100 that are adjacent to each other along the stacking direction X. As shown in FIG. 5 , the bus bar 302 includes a plate-shaped first joint portion 302a, a plate-shaped second joint portion 302b, and a curved connecting portion 302c. The first joint portion 302a is joined to the negative electrode terminal 104 of one adjacent cell 100. The second joint portion 302b is joined to the positive electrode terminal 103 of the other adjacent cell 100. The connecting portion 302c connects the first joint portion 302a and the second joint portion 302b. The bus bar 302 is formed from, for example, a clad material in which copper and aluminum are bonded together, copper, or aluminum.

[0059] When the bus bar 302 is made of a clad material, for example, the first joint portion 302a is made of copper and the second joint portion 302b is made of aluminum. When the negative electrode terminal 104 of the battery 100 is configured such that copper is converted to aluminum, the bus bar 302 may be configured such that the first joint portion 302a, the second joint portion 302b, and the connecting portion 302c are integrally formed of aluminum.

[0060] As shown in FIG. 2 , the second end bus bar 303 is joined to the negative electrode terminal 104 of the cell 100 that is closest to the second end block 212 among the 20 stacked cells 100 .

[0061] 5, the second end bus bar 303 includes a plate-shaped first joint portion 303a, a plate-shaped second joint portion 303b, a curved connecting portion 303c, and an insertion hole 303d. The first joint portion 303a is joined to the negative electrode terminal 104 of the cell 100. A bus bar that is electrically connected to an external control device is joined to the second joint portion 303b.

[0062] The connecting portion 303c connects the first joint portion 303a and the second joint portion 303b. The insertion hole 303d is formed in the second joint portion 303b. A fastening bolt is inserted into the insertion hole 303d. The second joint portion 303b and the bus bar that is electrically connected to an external control device are joined by the fastening bolt. The second end bus bar 303 is made of, for example, copper.

[0063] 1, the bus bar holder 311 integrally holds the first end bus bar 301, the plurality of bus bars 302, and the second end bus bar 303. The bus bar holder 311 also covers and insulates the stacked plurality of unit cells 100. As shown in FIG. 5, the bus bar holder 311 is formed in a plate shape.

[0064] A plurality of openings 311a are formed in the bus bar holder 311. Each opening 311a exposes the first joint portion or the second joint portion of the first end bus bar 301, the plurality of bus bars 302, and the second end bus bar 303 toward the side of the unit cells 100. Each opening 311a is larger than the first joint portion or the second joint portion of the corresponding bus bar.

[0065] A plurality of holding portions 311b are formed on the bus bar holder 311. Each holding portion 311b holds an end portion of the first joint portion or the second joint portion of the first end bus bar 301, the plurality of bus bars 302, and the second end bus bar 303. Each holding portion 311b is formed on the edge of the opening 311a.

[0066] Each holding portion 311b has a linear groove along the surface of the bus bar holder 311. An end of the first joint portion or the second joint portion of the corresponding bus bar is inserted into the groove provided in each holding portion 311b. The bus bar holder 311 is formed with a plurality of insertion portions 311c. Electric wires 502 of the temperature measurement unit 500 are inserted into the insertion portions 311c.

[0067] <Configuration of voltage detection unit 400> The voltage detection unit 400 shown in Figures 1, 2 and 5 detects the voltage of the cell 100 based on control by, for example, an external control device. As shown in Figure 5, the voltage detection unit 400 includes a voltage detection terminal 401 and an electric wire 402. The configuration included in the voltage detection unit 400 will be described below.

[0068] 5, the voltage detection terminal 401 is conductive and formed in a plate shape. The voltage detection terminal 401 is joined to the first end bus bar 301, the plurality of bus bars 302, and the second end bus bar 303 of the bus bar unit 300, respectively.

[0069] 5, the electric wire 402 is joined to the voltage detection terminal 401. The electric wire 402 provides electrical continuity between the voltage detection terminal 401 and an external control device.

[0070] <Configuration of Temperature Measurement Unit 500> The temperature measurement unit 500 shown in Figures 1, 2 and 5 measures the temperature of the battery 100 based on control by, for example, an external control device. As shown in Figure 2, the temperature measurement unit 500 includes a temperature sensor 501 and an electric wire 502. The configuration included in the temperature measurement unit 500 will be described below.

[0071] The temperature sensors 501 measure the temperatures of the cells 100. As shown in Fig. 2 , for example, the temperature sensors 501 are joined to the lids 102 of the seventh and fourteenth cells 100 from the first end block 211 to the second end block 212.

[0072] 2, the electric wire 502 is attached to the temperature sensor 501. The electric wire 502 provides electrical continuity between the temperature sensor 501 and an external control device.

[0073] 1, the battery pack 1 includes a gas exhaust unit 600 that moves gas exhausted from the cells 100. A brief description will be given below.

[0074] <Configuration of Gas Exhaust Unit 600> The gas exhaust unit 600 exhausts gas exhausted from the safety valve 105 of the cell 100 to the outside of the battery pack 1. As shown in Fig. 1 , the gas exhaust unit 600 includes a gas passage cover 601 and a fastening bolt 602. The configuration included in the gas exhaust unit 600 will be described below.

[0075] 1, the gas passage cover 601 includes a gas exhaust passage 601a, a gas exhaust pipe 601b, and a fixing portion 601c. The gas exhaust passage 601a is formed inside the gas passage cover 601 and extends along the stacking direction X. The gas exhaust passage 601a is shaped like a rectangular parallelepiped and has an internal space through which gas flows along the longitudinal direction. The gas passage cover 601 is integrally formed from synthetic resin, but may also be integrally formed with a metal frame or the like for reinforcement.

[0076] The gas exhaust pipe 601b is fluidly connected to the gas exhaust passage 601a and has the function of exhausting the gas flowing through the gas exhaust passage 601a. ​​The gas exhaust pipe 601b and the gas passage cover 601 are integrally formed by injection molding synthetic resin. It is also possible to form the gas exhaust pipe 601b and the gas passage cover 601 separately and then integrally form them by using an adhesive, friction welding, or other techniques.

[0077] The gas discharge passage 601a faces the safety valves 105 of the 20 stacked cells 100 via an internal space. The gas discharge passage 601a covers the safety valves 105 of the 20 stacked cells 100 and moves the gas discharged from the safety valves 105 toward the gas discharge pipe 601b.

[0078] 1, the gas exhaust pipe 601b opens at one end of the gas exhaust passage 601a in the longitudinal direction. The gas exhaust pipe 601b is formed in a cylindrical shape. The gas exhaust pipe 601b exhausts gas accumulated in the gas exhaust passage 601a to the outside. The gas exhaust pipe 601b is configured to be connected to an exhaust hose that exhausts the gas.

[0079] 7, the fixing portions 601c are formed at both ends of the gas discharge passage 601a in the longitudinal direction. The pair of fixing portions 601c are formed in a plate shape. The pair of fixing portions 601c are formed with holes into which the fastening bolts 602 are inserted.

[0080] 1, the fastening bolts 602 fix the gas passage cover 601 to the first end block 251 via the fixing portions 601c. Similarly, the fastening bolts 602 fix the gas passage cover 601 to the second end block 252 via the fixing portions 601c.

[0081] As shown in Figure 2, the gas passage cover 601, indicated by the dashed line, is disposed near the center of the battery pack 1 in a direction perpendicular to the longitudinal direction (stacking direction of the cells) so as to cover the safety valve 105. Therefore, the gas exhaust pipe 601b formed in the gas passage cover 601 is located above the safety valve 105. The gas exhaust pipe 601b is formed near the cell 100 on the end side of the battery pack 1, but is not limited to this position and may be located at any cell 100 position. However, the gas exhaust passage 601a needs to be disposed in a position along the row of the safety valves 105 of each cell 100.

[0082] <Configuration of Busbar Unit 300> The busbar unit 300 includes a first end busbar 301, a plurality of busbars 302, a second end busbar 303, and a busbar holder 311. To avoid interference with the gas passage cover 601, the busbar holder 311 is configured by removing a central portion of the busbar holder 311 shown in Fig. 5 along the stacking direction X. In other words, the busbar holders 311 are configured in pairs so as to be located at both ends in the width direction Y. However, a pair of busbar holders 311 can also be joined together to form a single plate-shaped busbar holder.

[0083] The phenomenon in which the gas exhaust pipe collapses and damages the safety valve in a battery pack configured as described above will be briefly explained using Figure 6. Note that since Figure 6 and subsequent figures have been partially changed from the configuration described above, new reference numerals will be used in the following explanation.

[0084] 6 shows the vicinity of the gas passage cover 11 in the battery pack 10 cut vertically toward the bottom surface of the cell 12 and viewed obliquely from above. Furthermore, the safety valve 105 (see FIG. 2) is not shown in FIG. 6 because it is located in front of the cut surface.

[0085] The cells 12 are stacked and arranged along the longitudinal direction (direction of arrow Ld) of the gas passage cover 11. A bus bar holder 13 is arranged between the cells 12 and the gas passage cover 11. Here, the bus bar holder 13 extends to the vicinity of the gas exhaust pipe 14. In addition, a bus bar holder cover 17 is arranged on the upper surface of the bus bar holder 13. The bus bar holder covers 17 are provided on both sides of the gas passage cover 11. The configuration of this part is different from that in FIG. 1.

[0086] Each cell 12 is provided with a safety valve, which is not shown in Fig. 6 due to the cross-sectional view. In reality, however, as shown in Fig. 2, the safety valve is located directly below the gas exhaust pipe 14. The gas exhaust pipe 14 and the gas passage cover 11 are integrally formed by injection molding using synthetic resin. When the safety valve 105 (see Fig. 2) of a certain cell 12 is ruptured to release gas, the gas flows through the space in the gas exhaust passage 15 of the gas passage cover 11 and is exhausted from the gas exhaust pipe 14.

[0087] In the case of the battery pack 10 having such a configuration, if the battery pack is inadvertently dropped, it may fall with the gas exhaust pipe 14 on the bottom. If the gas exhaust pipe 14 hits a workbench or the ground and an external force is applied to the gas exhaust pipe 14, the connection portion 16 between the gas exhaust pipe 14 and the gas passage cover 11 is broken, and the gas exhaust pipe 14 sinks inside the gas passage cover 11 (on the side of the single cells 12).

[0088] When the connecting portion 16 is broken, the gas exhaust pipe 14 collapses and moves toward the cell 12, as shown by the arrow Aw. This causes a collision between the inner tip 14E of the gas exhaust pipe 14 and the safety valve 105 (see FIG. 2). When the gas exhaust pipe 14 collapses inside the gas passage cover 11 in this way, the safety valve 105 (see FIG. 2) is ultimately damaged.

[0089] In order to solve these problems, the present invention proposes a battery pack equipped with a gas exhaust unit having the following configuration: Several embodiments of the present invention will be described below with reference to the drawings.

[0090] The first embodiment of the present invention is characterized in that a fragile portion, which is a portion with a collapse prevention function, is formed in a portion of the gas exhaust pipe 14 that protrudes outward from the gas passage cover 11. This fragile portion has less strength or rigidity than the connecting portion, and the gas exhaust pipe 14 is separated from the gas passage cover 11 before the connecting portion breaks. This prevents the gas exhaust pipe from collapsing.

[0091] 7 shows a first embodiment of the present invention. The gas exhaust pipe 14 and the gas passage cover 11 are integrally formed from synthetic resin. The gas exhaust pipe 14 has a cylindrical portion 14B that extends vertically outward (toward the opposite side from the cells 12) from the front surface 11S of the gas passage cover 11. The cylindrical portion 14B extends from the front surface 11S of the gas passage cover 11 to the outer tip portion 14P.

[0092] In addition, a large-diameter portion 14L is formed near the outer tip 14P of the tubular portion 14B of the gas exhaust pipe 14. This large-diameter portion 14L has a function of preventing the exhaust hose from coming off when inserted from the outside. Furthermore, it may also have a collapse prevention function as in the fourth embodiment described below (this will be described later).

[0093] The thickness (L1) of the gas passage cover 11 and the thickness (L2) of the cylindrical portion 14B of the gas exhaust pipe 14 are formed to be approximately the same thickness. Therefore, the connecting portion 16 that connects the gas passage cover 11 and the gas exhaust pipe 14 also has approximately the same thickness.

[0094] Meanwhile, a fragile portion 18A serving as a depression suppression function, which is a feature of this embodiment, is provided at the base of the cylindrical portion 14B of the gas exhaust pipe 14 connected to the front surface 11S of the gas passage cover 11. The fragile portion 18A may be formed at any position on the cylindrical portion 14B, but in this embodiment, it is formed directly above the front surface 11S of the gas passage cover 11. This fragile portion 18A is configured as an annular groove formed by cutting out a predetermined shape from the outer periphery of the gas exhaust pipe 14. Hereinafter, the annular groove will also be referred to as "18A." Herein, the annular groove is described as a continuous groove, but grooves formed at intervals, for example, also fall within the category of annular grooves.

[0095] The annular groove 18A is formed as a groove extending from the outer peripheral surface of the gas exhaust pipe 14 toward the inner peripheral surface thereof, and is formed in a shape that is approximately parallel to the front surface 11S of the gas passage cover 11 or along the front surface 11S.

[0096] In this embodiment, the groove is formed in a triangular shape that tapers toward the inner periphery. Therefore, the thickness (L3) of the cylindrical portion 14B of the gas exhaust pipe 14 where the annular groove 18A is formed is thinner than the thickness (L2) of the cylindrical portion 14B of the gas exhaust pipe 14 other than the portion where the annular groove 18A is formed and the thickness (L1) of the gas passage cover 11. In other words, the relationship "L3 < L1 ≒ L2" holds. The annular groove 18A can also be referred to as a reduced diameter portion.

[0097] Therefore, the annular groove 18A has a thinner wall thickness than other parts of the cylindrical portion 14B of the gas exhaust pipe 14, so that the mechanical strength or rigidity is reduced, and furthermore, because of its cutout shape, the structure is prone to stress concentration.

[0098] Next, the function and effect of providing the fragile portion 18A having such a shape will be described. Suppose that the battery pack 10 is inadvertently dropped so that the gas exhaust pipe 14 is on the bottom. The gas exhaust pipe 14 then hits a workbench or the ground, and an external force is applied to the gas exhaust pipe 14.

[0099] In this state, the external force applied to the gas exhaust pipe 14 is mainly exerted on the gas exhaust pipe 14 and the connecting portion 16, but because the thickness (L3) of the annular groove that constitutes the fragile portion 18A is thin and stress is concentrated therein, when an external force is applied, the fragile portion 18A of the gas exhaust pipe 14 breaks first, as if bending, relative to the connecting portion 16.

[0100] Therefore, the broken gas exhaust pipe 14 dissipates outside the battery pack 10 and does not sink into the interior of the gas passage cover 11, thereby preventing damage to the safety valve 105 (see FIG. 2).

[0101] Thus, according to this embodiment, even if the gas exhaust pipe 14 collides with a workbench or the ground and an external force is applied, the phenomenon in which the gas exhaust pipe 14 collapses inside the gas passage cover 11 and damages the safety valve 105 (see Figure 2) can be prevented.

[0102] Here, the groove shape of the annular groove that constitutes the fragile portion 18A is triangular, but it may also be rectangular or arc-shaped. Even with these shapes, the thickness of the portion where the annular groove 18A is formed can be made thinner, and the notch effect can be used to increase stress concentration.

[0103] Furthermore, although the annular groove 18A is formed parallel to the front surface 11S of the gas passage cover 11, the fragile portion 18B may be formed at an angle relative to the front surface 11S. Even with this shape, as described above, the thickness (L3) of the annular groove forming the fragile portion 18B is thin and stress is concentrated therein, so that when an external force is applied, the fragile portion 18B of the gas exhaust pipe 14 breaks before the connecting portion 16. Therefore, the broken gas exhaust pipe 14 does not collapse into the interior of the gas passage cover 11, and damage to the safety valve 105 (see FIG. 2) can be avoided.

[0104] In this way, even if the gas exhaust pipe 14 of the gas passage cover 11 breaks, the safety valve of the cell 12 is not damaged, so the cell 12 can be used as is. Therefore, in this case, if the gas passage cover 11 is replaced with a new one, a new battery pack 10 can be manufactured.

[0105] Next, a second embodiment of the present invention will be described with reference to Figures 8 to 11. The second embodiment is characterized in that the base side of the tubular portion 14B of the gas exhaust pipe 14, which protrudes vertically outward from the gas passage cover 11, has a predetermined thickness (thick-walled region), and the tip side is formed to have a thickness (thin-walled region) thinner than the thickness of the base side, and the boundary between the thick-walled region and the thin-walled region is formed so as to be obliquely inclined with respect to the axis of the gas exhaust pipe 14.

[0106] 8 and 9 show the appearance of the gas exhaust pipe 14 according to this embodiment, and FIGS. 10 and 11 show the longitudinal cross section of the gas exhaust pipe 14 shown in FIGS.

[0107] 8 and 9, the gas exhaust pipe 14 has a cylindrical portion 14B that rises vertically from the front surface 11S of the gas passage cover 11. A thick-walled portion 19 is formed over a predetermined distance from the base side of the cylindrical portion 14B (near the connecting portion 16). The thickness of this thick-walled portion 19 is (L2), as shown in FIG. 11, and is approximately the same as the thickness (L1) of the gas passage cover 11.

[0108] On the other hand, a thin-walled portion 20 is formed from the thick-walled portion 19 of the gas exhaust pipe 14 to the outer tip end portion 14P, and the thickness of this thin-walled portion 20 is a thickness (L3) as shown in FIG. 11 , which is thinner than the thick-walled portion 19. In other words, there is a relationship of "L3 < L1 ≒ L2." As a result, a step 21 is formed at the boundary between the thick-walled portion 19 and the thin-walled portion 20. In this embodiment, this step 21 functions as a fragile portion. Hereinafter, the step 21 may also be referred to as the fragile portion 21.

[0109] 9, in a side view of the gas exhaust pipe 14 relative to the axis (C), the boundary line (the step line) between the thick-walled portion 19 and the thin-walled portion 20 is inclined so as to form a predetermined inclination angle (θ1) with respect to the axis (C). Here, the inclination angle (θ1) is the inclination angle with respect to the front surface 11S of the gas passage cover 11.

[0110] In this way, as in the first embodiment, the step 21 between the thick-walled portion 19 and the thin-walled portion 20 is formed at an angle to serve as a depression prevention function, so that when an external force is applied, the gas exhaust pipe 14 breaks by falling in a direction along the front surface 11S. This prevents the broken gas exhaust pipe 14 from entering the inside of the gas exhaust cover 11, and prevents damage to the safety valve of the single cell 12.

[0111] Here, the inclination angle (θ1) of the step 21 between the thick portion 19 and the thin portion 20 can be any angle, but in this embodiment it is set in the range of 10° to 15°.

[0112] Next, the function and effect of providing the fragile portion 21 having such a shape will be described. Suppose that the battery pack 10 is inadvertently dropped so that the gas exhaust pipe 14 is on the bottom. Then, the gas exhaust pipe 14 hits a workbench or the ground, and an external force is applied to the gas exhaust pipe 14.

[0113] In this state, the external force acting on the gas exhaust pipe 14 is mainly exerted on the gas exhaust pipe 14 and the connecting portion 16, but because the thickness (L3) of the thin-walled portion 20 constituting the fragile portion 21 is thin and the connecting portion of the boundary between the thick-walled portion 19 and the thin-walled portion 20 of the step portion 21 is nearly at a right angle, the shape is prone to a notch effect and stress is concentrated, so when an external force is applied, the fragile portion 21 of the gas exhaust pipe 14 breaks before the connecting portion 16.

[0114] Furthermore, the step 21 at the boundary between the thick portion 19 and the thin portion 20 is formed at an angle with respect to the axis (C). This allows the gas exhaust pipe 14 to break by falling in a direction along the front surface 11S when an external force is applied. Therefore, the broken gas exhaust pipe 14 does not enter the inside of the gas exhaust cover 11, and damage to the safety valve of the cell 12 can be avoided.

[0115] In this way, even in this embodiment, even if the gas exhaust pipe 14 collides with a workbench or the ground and an external force is applied, the phenomenon in which the gas exhaust pipe 14 collapses inside the gas passage cover 11 and damages the safety valve 105 (see Figure 2) can be prevented.

[0116] Even if the gas exhaust pipe 14 of the gas passage cover 11 is damaged, the safety valve of the cell 12 is not damaged, so the cell 12 can be used as is. Therefore, in this case, if the gas passage cover 11 is replaced with a new one, a new battery pack 10 can be manufactured.

[0117] 11, an annular groove 22, as shown in FIG. 7, can be formed above the boundary between the thick-walled portion 19 and the thin-walled portion 20. The provision of this annular groove 22 makes it even easier to break the gas exhaust pipe 14. <Modifications> FIG. 12 shows a modification of the embodiment shown in FIGS. 8 to 11. In this modification, the base side of the tubular portion 14B of the gas exhaust pipe 14 protruding outward from the gas passage cover 11 is formed as a thick-walled portion 19 having a predetermined thickness, and the tip side is formed as a thin-walled portion 20 that is thinner than the base side. The boundary between the thick-walled portion 19 and the thin-walled portion 20 is formed as a fragile portion 21A, and the fragile portion 21A is formed parallel to the front surface 11S of the gas passage cover 11.

[0118] 12, the gas exhaust pipe 14 rises vertically from the gas passage cover 11, and has a thick-walled portion 19 formed over a predetermined distance from the base side (near the connecting portion 16). The thickness of this thick-walled portion 19 is (L2), which is approximately the same as the thickness (L1) of the gas passage cover 11.

[0119] Meanwhile, a thin-walled portion 20 is formed from the thick-walled portion 19 of the gas exhaust pipe 14 to the outer tip end 14P, and the thickness of this thin-walled portion 20 is (L3), which is thinner than the thick-walled portion 19. Therefore, the boundary between the thick-walled portion 19 and the thin-walled portion 20 becomes a weak portion 21A. Furthermore, since the connection portion of this boundary is nearly a right angle, it has a shape that is prone to the notch effect (stress concentration). In this case, as in the first embodiment, by making the boundary between the thick-walled portion 19 and the thin-walled portion 20 the weak portion 21A, it functions as a depression suppression portion.

[0120] In this modification, an annular groove as shown in Fig. 7 can also be formed above the boundary between the thick-walled portion 19 and the thin-walled portion 20. Providing this annular groove makes it even easier to break the gas exhaust pipe 14.

[0121] In this way, because the thin-walled portion 20 forming the fragile portion 21A is thin and stress is concentrated therein, when an external force is applied, the fragile portion 21A of the gas exhaust pipe 14 breaks before the connecting portion 16. Therefore, the broken gas exhaust pipe 14 does not collapse into the interior of the gas passage cover 11, and damage to the safety valve 105 (see FIG. 2) can be avoided.

[0122] Next, a third embodiment of the present invention will be described with reference to Figures 13 and 14. The third embodiment is characterized in that the tip of the outer tip portion 14P of the gas exhaust pipe 14, which protrudes vertically outward from the gas passage cover 11, is formed so as to be inclined obliquely with respect to the axis of the gas exhaust pipe 14.

[0123] FIG. 13 shows the external appearance of the side of the gas exhaust pipe 14 according to this embodiment, and FIG. 14 shows a vertical cross section of FIG.

[0124] 13 and 14, the gas exhaust pipe 14 rises vertically from the front surface 11S of the gas passage cover 11, and a straight tubular section 14B is formed over a predetermined distance from the base side (near the connecting portion 16). A large-diameter section 14L is formed midway along the tubular section 14B, and has the function of preventing the exhaust hose from coming off when inserted from the outside.

[0125] In this embodiment, an inclined surface 14i inclined in an oblique direction is formed on the outer tip end 14P. This inclined surface 14i is inclined at a predetermined inclination angle (θ2) with respect to the axis (C) of the gas exhaust pipe 14. In this embodiment, this inclined surface 14i functions as a depression suppression function part.

[0126] The inclined surface portion 14i has a tip portion 14T that is the farthest point of the inclined surface portion 14i from the front flat surface 11S. Therefore, when the gas exhaust pipe 14 is dropped with the tip portion 14T facing downwards, it will hit a workbench or the ground, and the inclined surface portion 14i on which the tip portion 14T is formed will be subjected to a lateral force upon impact.

[0127] Therefore, the gas exhaust pipe 14 does not collapse toward the cell 12, but collapses and breaks. This prevents the gas exhaust pipe 14 from collapsing inside the gas passage cover 11 and damaging the safety valve 105 (see FIG. 2). In this embodiment, the inclined surface portion is described as having a continuous slope, but is not limited to this and may be a stepped portion having a stepped slope.

[0128] Even if the gas exhaust pipe 14 of the gas passage cover 11 is damaged, the safety valve of the cell 12 is not damaged, so the cell 12 can be used as is. Therefore, in this case, if the gas passage cover 11 is replaced with a new one, a new battery pack 10 can be manufactured.

[0129] Next, a fourth embodiment of the present invention will be described with reference to Fig. 15. The fourth embodiment is characterized in that, even if the gas exhaust pipe 14 is depressed inside the gas passage cover 11 when an external force is applied to the gas exhaust pipe 14, the length of the inner tip 14E of the gas exhaust pipe 14 is set so that it does not reach the safety valve 105.

[0130] 15, the outer diameter (D1) of the depressed region 14C between the large-diameter portion 14L and the front-side flat surface 11S in the tubular portion 14B of the gas discharge pipe 14 is shorter than the outer diameter (D2) of the large-diameter portion 14L. Therefore, if the connecting portion 16 of the gas discharge pipe 14 breaks and the gas discharge pipe 14 collapses, the large-diameter portion 14L can engage with the depression in the front-side flat surface 11S and prevent the gas discharge pipe 14 from collapsing.

[0131] On the other hand, the axial length of the recessed region 14C is set to a recessed region length (L4). This recessed region length (L4) is the length from the rear flat surface 11R of the gas passage cover 11 to the surface of the large-diameter portion 14L on the side of the front flat surface 11S. Furthermore, the length from the inner tip 14E to the outer tip 14P of the gas exhaust pipe 14 is the exhaust pipe length (L5).

[0132] The length from the front surface 11S of the gas passage cover 11 to the surface of the safety valve 105 of the battery cell 12 is set to the gap length (L6). The relationship between the recessed area length (L4), the exhaust pipe length (L5), and the gap length (L6) is "L4<L5<L6."

[0133] Next, the function and effect of providing the fragile portion 18A having such a shape will be described. Suppose that the battery pack 10 is inadvertently dropped so that the gas exhaust pipe 14 is on the bottom. The gas exhaust pipe 14 then hits a workbench or the ground, and an external force is applied to the gas exhaust pipe 14.

[0134] In this state, the external force acting on the gas exhaust pipe 14 is mainly at the gas exhaust pipe 14 and the connecting portion 16, and the application of the external force causes the connecting portion 16 of the gas exhaust pipe 14 to break. The broken gas exhaust pipe 14 then collapses toward the cell 12, but because the outer diameter (D2) of the large-diameter portion 14L of the gas exhaust pipe 14 is longer than the outer diameter (D1) of the collapsed region of the gas exhaust pipe 14, the large-diameter portion 14L of the gas exhaust pipe 14 engages with the collapsed hole in the front-side flat surface 11S of the gas passage cover 11, and the collapse of the gas exhaust pipe 14 is stopped (collapse prevention function).

[0135] At this time, since the length (L4) of the recessed region of the gas exhaust pipe 14 is shorter than the length (L6) of the gap between the gas passage cover 11 and the safety valve 105 of the battery 12, the inner tip 14E of the gas exhaust pipe 14 does not reach the safety valve 105. Therefore, even if the broken gas exhaust pipe 14 recesses into the inside of the gas passage cover 11, it does not reach the safety valve 105, so that damage to the safety valve 105 can be avoided.

[0136] On the other hand, it is also conceivable that the large diameter portion 14L of the gas exhaust pipe 14 breaks through a depression in the front flat surface 11S of the gas passage cover 11, causing the gas exhaust pipe 14 to sink into the gas passage cover 11.

[0137] In this case, the length (L5) of the gas exhaust pipe 14 is shorter than the gap length (L6) between the gas passage cover 11 and the safety valve 105 of the battery 12, so the inner tip 14E of the gas exhaust pipe 14 does not reach the safety valve 105. Therefore, even if the entire broken gas exhaust pipe 14 collapses into the interior of the gas passage cover 11, it does not reach the safety valve 105, so damage to the safety valve 105 can be avoided.

[0138] Even if the gas exhaust pipe 14 of the gas passage cover 11 is damaged, the safety valve of the cell 12 is not damaged, so the cell 12 can be used as is. Therefore, in this case, if the gas passage cover 11 is replaced with a new one, a new battery pack 10 can be manufactured.

[0139] In some of the above-described embodiments, the following configuration can be additionally adopted. For example, the bus bar holder 13 can be configured to extend beyond the gas exhaust pipe 14 toward the safety valve 105. In this case, it is necessary to provide a gas exhaust hole in the extended portion where the safety valve 105 is located.

[0140] By adding such a configuration, even if the broken gas exhaust pipe 14 collapses inside the gas passage cover 11, the gas exhaust pipe 14 is prevented from collapsing by the bus bar holder 13, and damage to the safety valve 105 can be avoided.

[0141] As described above, the present invention is characterized in that an assembled battery in which a plurality of cells each having a safety valve are stacked includes a gas passage cover made of synthetic resin, disposed opposite the safety valve and having a gas exhaust passage formed therein for flowing gas exhausted from the safety valves of the plurality of cells, and a gas exhaust pipe formed integrally with the gas passage cover and extending in a direction away from the cells for discharging gas in the gas exhaust passage to the outside, the gas exhaust pipe being structured so as not to collapse inside the gas passage cover when an external force is applied thereto.

[0142] The present invention also provides a battery pack in which a plurality of cells each having a safety valve are stacked, the battery pack comprising: a gas passage cover made of synthetic resin, disposed opposite the safety valve, and having formed therein a gas exhaust passage for passing gas exhausted from the safety valves of the plurality of cells; and a gas exhaust pipe formed integrally with the gas passage cover, extending in a direction away from the cells, for discharging gas in the gas exhaust passage to the outside, the gas exhaust pipe being set to a length such that the gas exhaust pipe will not reach the safety valve even if it collapses inside the gas passage cover when an external force is applied.

[0143] This prevents the gas exhaust pipe from colliding with a workbench or the ground and being subjected to an external force, thereby preventing the gas exhaust pipe from sinking inside the gas passage cover and damaging the safety valve.

[0144] The present invention is not limited to the above-described embodiments, but includes various modifications. The above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace other configurations with respect to the configuration of each embodiment.

[0145] 1... battery pack, 100... single cell, 101... container, 102... lid, 103... positive electrode terminal, 104... negative electrode terminal, 105... safety valve, 200... holding unit, 201... first end spacer, 203... second end spacer, 211... first end block, 212... second end block, 231... first side plate, 232... second side plate, 300... bus bar unit, 311... bus bar holder, 400... voltage detection unit, 500... temperature measurement unit, 600... gas exhaust unit, 601... gas duct, 601a... gas movement passage, 601b... gas exhaust pipe.

Claims

1. An assembled battery in which a plurality of cells each having a safety valve are stacked, comprising: a gas passage cover disposed opposite the safety valve and having a gas exhaust passage formed therein through which gas exhausted from the safety valves of the plurality of cells flows; and a gas exhaust pipe provided on the gas passage cover and extending in a direction away from the cells for exhausting gas in the gas exhaust passage to the outside, wherein the gas exhaust pipe is formed with a collapse prevention function portion that prevents it from collapsing inside the gas passage cover when an external force is applied.

2. The battery pack according to claim 1, wherein the depression prevention function portion is a fragile portion formed in a part of a cylindrical portion that forms the gas exhaust pipe.

3. The battery pack according to claim 2, wherein the fragile portion is an annular groove formed on the outer periphery of the cylindrical portion.

4. The battery pack according to claim 3, wherein the annular groove is one of a triangular, rectangular or arc-shaped cross section formed on the outer periphery of the cylindrical portion.

5. A battery pack according to claim 2, wherein the fragile portion is an annular step formed between a thick portion formed on the side of the gas passage cover formed on the cylindrical portion and a thin portion formed between the thick portion and the tip of the cylindrical portion.

6. The battery pack according to claim 5, wherein the annular step is formed at an angle with respect to the axis of the gas exhaust pipe when viewed from the side of the cylindrical portion.

7. The battery pack according to claim 5, wherein the annular step is formed in a direction along the front surface of the gas passage cover when viewed from the side of the cylindrical portion.

8. The battery pack according to claim 1, wherein the depression prevention function portion is an inclined surface portion or a stepped portion formed at the tip of a cylindrical portion forming the gas exhaust pipe, and inclined relative to the axis of the gas exhaust pipe when viewed from the side of the cylindrical portion.

9. An assembled battery in which a plurality of cells each having a safety valve are stacked, comprising: a gas passage cover made of synthetic resin, disposed opposite the safety valve, and having formed therein a gas exhaust passage for allowing gas exhausted from the safety valves of the plurality of cells to flow; and a gas exhaust pipe attached to the gas passage cover, extending in a direction away from the cells, for exhausting gas in the gas exhaust passage to the outside, wherein the length of the gas exhaust pipe is determined so that it will not reach the safety valve if an external force is applied and the gas exhaust pipe collapses inside the gas passage cover.

10. The battery pack according to claim 9, wherein the length (L5) of the gas exhaust pipe is set to be shorter than the gap length (L6) from the safety valve of the cell to the gas passage cover.

11. A battery pack according to claim 10, wherein the exhaust pipe length (L5) of the gas exhaust pipe is the length from the inner tip to the outer tip of the gas exhaust pipe, and the gap length (L6) is the length from the safety valve of the cell to the front flat surface of the gas passage cover.

12. The battery pack according to any one of claims 1 to 11, wherein a bus bar holder for holding a bus bar is disposed on the gas passage cover side of the safety valve, the bus bar holder extends to a position beyond at least the gas exhaust pipe, and a gas exhaust hole is formed in the portion where the safety valve is located.

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