JP2022053879A - Battery case and battery for electrically power-assisted bicycle - Google Patents

Abstract

To suppress a case from opening wide when the cell inside a battery case expands by preventing a first case and a second case from being separated from each other.SOLUTION: A battery case in one example of an embodiment includes a first case and a second case each having an opening. Interior space for accommodating cells is formed by overlapping the first case and the second case. The battery case includes: a fixing part that fixes the first case and the second case; and an engagement part that maintains the connection state of the first case and the second case in a state where the interior space has expanded more than it is fixed at the fixing part.SELECTED DRAWING: Figure 4

Description

The present disclosure relates to a battery case and a battery for an electrically power assisted bicycle provided with the case.

Conventionally, an electrically assisted bicycle that assists a user in pedaling force by a motor is widely known. The electrically power assisted bicycle is equipped with a battery for supplying electric power to the motor. The battery generally includes a battery case and a cell housed in the case, and is detachably attached to a battery mounting portion provided on a bicycle frame (see, for example, Patent Documents 1 and 2). ). The battery case is, for example, a resin case including a first case and a second case fixed to each other, and a plurality of secondary batteries such as a laminated cell and a cylindrical cell are housed in the internal space thereof.

Japanese Unexamined Patent Publication No. 2012-104501 JP-A-2015-143035

By the way, the cell housed in the battery case may be greatly expanded due to, for example, a gas generated by deterioration. If the cell expands significantly, it is assumed that the battery case will be damaged, and the first case and the second case may be separated and the case may be wide open to expose the cell.

An object of the present disclosure is to prevent the first case and the second case from separating from each other and widening the case, for example, when the cell in the battery case expands. It should be noted that a method of suppressing damage to the case by providing a space for absorbing the expansion of the cell in the case is conceivable, but in this case, there is a problem that the battery becomes large.

The battery case according to one aspect of the present disclosure includes a first case and a second case having openings, respectively, and a battery case in which an internal space for accommodating a cell is formed by superimposing the first case and the second case. The engagement between the fixed portion for fixing the first case and the second case and the engaged state for maintaining the connected state between the first case and the second case in a state where the internal space is expanded more than the state fixed by the fixed portion. It is characterized by having a part.

The battery for an electrically assisted bicycle according to one aspect of the present disclosure includes the above battery case and a cell housed in the battery case, and the battery case is a battery of a charger and an electrically assisted bicycle in a state where the internal space is expanded. It is configured so that it does not fit into the installation part.

According to one aspect of the present disclosure, for example, when a cell in a battery case expands, it is possible to prevent the first case and the second case from separating and widening the case. In the battery case which is one aspect of the present disclosure, even if the cell expands and the fixed portion is disengaged, the internal space is expanded by the engaging portion as compared with the state where the fixed portion is fixed. The connected state of the second case is maintained. Therefore, damage to the case where the cell is largely exposed is suppressed.

It is a figure which shows the electric assist bicycle which is an example of an embodiment. It is a side view of the battery for electric assist bicycle which is an example of embodiment. It is a vertical sectional view of the battery for electric assist bicycle which is an example of embodiment. It is a cross-sectional view (not shown) of the battery for the electric assist bicycle which is an example of embodiment. It is an enlarged view of the engaging part which is an example of an embodiment. It is a side view of the battery for the electric assist bicycle which is an example of an embodiment, and shows the state which the case is expanded by the expansion of a cell. It is a cross-sectional view (not shown) of the battery for the electric assist bicycle which is an example of an embodiment, and shows the state which the case expanded by the expansion of a cell. It is an enlarged view of the engaging part which is an example of an embodiment, and shows the state which the case is expanded by the expansion of a cell. It is a figure which shows the battery case for the electric assist bicycle which is another example of an embodiment. It is a figure which shows the battery case for the electric assist bicycle which is another example of an embodiment.

Hereinafter, an embodiment of the battery case according to the present disclosure and the battery for an electrically power assisted bicycle provided with the battery case will be described in detail with reference to the drawings. The embodiments described below are merely examples, and the present disclosure is not limited to the following embodiments. Further, it is assumed from the beginning that a plurality of embodiments and modifications described below are selectively combined.

In the following, a battery case applied to a battery for an electrically power assisted bicycle will be illustrated, but the battery case according to the present disclosure is not limited to this, and is applied to, for example, a battery for an automobile, a battery for a mobile device, a battery for a power storage system, and the like. You can also do it.

FIG. 1 is a diagram showing an electrically assisted bicycle 1 which is an example of an embodiment. The electrically assisted bicycle of the present disclosure is not limited to the city cycle as illustrated in FIG. 1, and may be, for example, a sports cycle, a foldable bicycle, or the like.

As shown in FIG. 1, the electrically assisted bicycle 1 includes a battery 10 and a motor unit 11 driven by electric power supplied from the battery 10. Further, the electrically assisted bicycle 1 includes a frame 2, a front wheel 3a, a rear wheel 3b, a handle 4, a saddle 5, a crank arm 6, a pedal 7, a chain 8, and a headlight 9 like a general bicycle. The electrically assisted bicycle 1 is a bicycle that assists the force of the user stepping on the pedal 7 by a motor built in the motor unit 11.

The frame 2 is a frame for connecting the front wheels 3a, the rear wheels 3b, the handle 4, the saddle 5, and the like, and is configured by welding a plurality of pipes. In the present embodiment, as a plurality of pipes, a head pipe 2a, a front fork 2b, a down pipe 2c, a seat pipe 2d, a chain stay 2e, a seat stay 2f, and a bottom bracket (not shown) are provided. The bottom bracket is a pipe that connects the down pipe 2c, the seat pipe 2d, and the chain stay 2e.

The battery 10 is detachably attached to the battery mounting portion 12 provided on the frame 2. The battery installation unit 12 has, for example, a structure in which the lower portion of the battery 10 can be set. Further, a plurality of terminals to be inserted into the battery 10 are arranged in the battery installation unit 12. Generally, the battery 10 is removed from the battery installation unit 12 when the amount of charge becomes low, and is charged using a predetermined charger. The seat pipe 2d may be provided with a lock device for fixing the battery 10.

Hereinafter, the battery 10 as an example of the embodiment will be described in detail with reference to FIGS. 2 to 8. 2 to 5 are views showing an initial state of the battery 10 (a state in which the cell 50 is not expanded). 6 to 8 are views showing a state in which the battery case 13 is expanded due to the expansion of the cell 50.

In the following, for convenience of explanation, terms indicating directions such as up / down, left / right (horizontal), front / back, etc. are used. Specifically, the direction along the longitudinal direction of the battery 10 is the vertical direction, the direction in which the first case 20 and the second case 30 are lined up is the front-rear direction (front of the first case 20 side), and orthogonal to the vertical direction and the front-rear direction. The direction to do is the horizontal direction.

FIG. 2 is a side view of the battery 10, and FIG. 3 is a vertical sectional view of the battery 10. As shown in FIGS. 2 and 3, the battery 10 includes a battery case 13 and a cell 50 housed in the battery case 13. A secondary battery such as a lithium ion battery is used for the cell 50. The battery 10 includes, for example, a plurality of cells 50 connected in series and a protective substrate 51. The protective substrate 51 is generally called a BMS substrate, monitors the state of the cell 50, and realizes optimum charge / discharge control of the cell 50.

The cell 50 contains a group of electrodes and an electrolyte contained in the outer body. The structure of the cell 50 is not particularly limited, but a preferred example thereof includes a laminated cell, a cylindrical cell, and the like. The laminated cell comprises an exterior body made of a laminated sheet containing a metal layer such as aluminum. The cylindrical cell comprises a bottomed cylindrical metal exterior. It is preferable that the plurality of cells 50 are housed in the internal space 14 of the battery case 13 in a state of being integrated with an adhesive, an adhesive tape, a package, or the like, or stored in a predetermined holder.

For example, the cell 50 may gradually deteriorate due to long-term use, and may expand due to decomposition of an electrolyte or the like to generate gas. In particular, in a laminated cell, volume expansion due to deterioration is likely to occur. As will be described in detail later, according to the battery case 13, damage to the case where the first case 20 and the second case 30 are separated and the cell 50 is greatly exposed is suppressed when the cell 50 is greatly expanded. .. Further, when an abnormality occurs in the cell 50, it is assumed that gas is ejected from the cell 50 into the battery case 13, and the battery case 13 can cope with such a situation.

The battery case 13 includes a first case 20 and a second case 30 having openings, respectively, and has an internal space 14 capable of accommodating a plurality of cells 50. In the battery case 13, the internal space 14 isolated from the outside is formed by superimposing the first case 20 and the second case 30. The first case 20 and the second case 30 have a shape in which the peripheral edges of the openings can be overlapped with each other, and the closed internal space 14 is formed by the overlapping.

The battery case 13 may be a metal case, but is preferably a resin case from the viewpoint of light weight, moldability, and the like. The battery case 13 is generally opaque and conceals the cell 50 and the like housed in the internal space 14. In the present embodiment, the lower portion of the battery case 13 is thinner than the upper portion, and the narrowed lower portion is inserted into the battery mounting portion 12 and the charger. On the other hand, as will be described in detail later, when the cell 50 is expanded and the battery case 13 is expanded, the lower portion of the battery case 13 cannot be inserted into the battery mounting portion 12 and the charger.

At the lower part of the battery case 13, for example, two convex portions 24 protruding to the left and right are formed. The battery installation portion 12 and the charger are provided with a concave portion into which the convex portion 24 fits. Further, a handle 25 used for carrying the battery 10, for example, is formed on the upper portion of the battery case 13. In the example shown in FIG. 2, the convex portion 24 and the handle 25 are formed in the first case 20, but these may be formed in the second case 30.

As described above, the battery case 13 is configured by connecting the first case 20 and the second case 30. The first case 20 includes a substantially rectangular front surface portion 20A long in the vertical direction, two side surface portions 20B, an upper surface portion 20C, and a lower surface portion 20D, and an opening is formed at a position facing the front surface portion 20A. Has a structure that has been made. The side surface portion 20B, the upper surface portion 20C, and the lower surface portion 20D are formed, for example, substantially perpendicular to the front surface portion 20A. Similarly, the second case 30 includes a rear surface portion 30A, a side surface portion 30B, an upper surface portion 30C, and a lower surface portion 30D, and has a structure in which an opening is formed at a position facing the rear surface portion 30A.

The battery case 13 includes a fixing portion 40 for fixing the first case 20 and the second case 30. For example, two fixing portions 40 are provided at the upper portion and the lower portion of the battery case 13, for a total of four fixing portions 40. The fixing portions 40 are arranged one on each of the left and right sides side by side in the upper part of the battery case 13, and similarly, one on each of the left and right sides in the lower part of the battery case 13. The fixed portion 40 is formed in the internal space 14, and a plurality of cells 50 are arranged between the upper and lower fixed portions 40.

FIG. 4 is a cross-sectional view of the battery 10 in the horizontal direction (cell 50 and the like are not shown). In the present embodiment, the fixing portion 40 and the engaging portion 41 described later are not formed side by side in the lateral direction, but for convenience of explanation, both cross-sectional shapes are shown in FIG. As shown in FIG. 4, the fixing portion 40 is preferably configured to fasten the first case 20 and the second case 30 using screws 42.

The fixing portion 40 includes a boss portion 21 formed in the first case 20, a screw insertion portion 31 formed in the second case 30, and a screw 42 inserted into the screw insertion portion 31 and fastened to the boss portion 21. including. The fixing method of the two cases is not limited to screwing, and may be fixed by, for example, rivets or welding. It should be noted that the fixing portion 40 is detached (broken) before the other parts of the case are damaged when the cell 50 is greatly expanded or when an abnormality occurs in the cell 50 and gas is ejected from the cell 50. It is preferable that it is designed to.

The boss portion 21 extends from the front surface portion 20A of the first case 20 toward the opening side (rear), and is formed in a cylindrical shape into which the shaft of the screw 42 can be inserted. Further, a screw groove is formed in the cylinder of the boss portion 21. The boss portion 21 is formed, for example, substantially perpendicular to the inner surface of the front surface portion 20A, and extends to or near the opening of the first case 20. Alternatively, the boss portion 21 may extend beyond the opening to the inside of the second case 30.

The screw insertion portion 31 is formed in a cylindrical shape into which a screw 42 can be inserted at a position facing the boss portion 21 of the second case 30. The screw insertion portion 31 extends from the rear surface portion 30A of the second case 30 to the opening or its vicinity, and is formed substantially perpendicular to the rear surface portion 30A. Further, the screw insertion portion 31 is open toward the rear. That is, an opening of the screw insertion portion 31 is formed in the rear surface portion 30A.

In the present embodiment, the tip of the screw insertion portion 31 is in contact with the tip of the boss portion 21. A hole through which the shaft of the screw 42 passes is formed at the tip of the screw insertion portion 31. This hole has a size that allows the shaft of the screw 42 to pass through and does not allow the head to pass through. The screw 42 inserted into the cylinder of the screw insertion portion 31 from the opening of the rear surface portion 30A is locked in a state where the shaft extends from this hole and the head is caught on the edge of the hole. Then, the shaft of the screw 42 extending from the screw insertion portion 31 is fastened to the boss portion 21, so that the first case 20 and the second case 30 are screwed together.

FIG. 5 is an enlarged view of the engaging portion 41. As shown in FIGS. 4 and 5, the battery case 13 further includes an engaging portion 41 for fixing the first case 20 and the second case 30. The engaging portion 41 has a function of maintaining a connected state between the first case 20 and the second case 30 in a state where the internal space 14 is expanded more than the state fixed by the fixing portion 40. The engaging portion 41 is formed on both the left and right sides of the battery case 13 in another portion separated from the fixing portion 40.

Here, "when the fixing portion 40 comes off" means, for example, when the screw 42 comes off from the boss portion 21, or when the boss portion 21 or the like is broken as shown in FIG. 7, the two cases are fixed by the fixing portion 40. Means when can no longer be maintained. The engaging portion 41 secures a connected state between the first case 20 and the second case 30 when the fixing portion 40 is disengaged and the battery case 13 expands in the front-rear direction, and the two cases are separated and the case is wide open. Prevent that.

The engaging portion 41 is formed on the side surface portion of the battery case 13. In this case, the engaging portion 41 may be formed at a position laterally aligned with the cell 50. For example, two engaging portions 41 are provided at the upper portion and the lower portion of the battery case 13, for a total of four engaging portions 41. The engaging portions 41 are arranged one on each of the left and right sides side by side in the upper part of the battery case 13, and similarly, one on each of the left and right sides in the lower part of the battery case 13. The number of engaging portions 41 may be larger than the number of fixed portions 40.

The engaging portion 41 includes a claw 22 formed on the side surface portion 20B of the first case 20 and a tongue piece portion 32 formed on the side surface portion 30B of the second case 30. The claw 22 is a convex portion protruding inward of the case from the inner surface of the side surface portion 20B. The tongue piece portion 32 extends from the end of the side surface portion 30B toward the first case 20, and is arranged inside the case with respect to the side surface portion 20B. Further, the tongue piece portion 32 is formed with an opening 33 as a receiving portion into which the claw 22 is inserted. The tongue piece portion 32 is arranged along the inner surface of the side surface portion 20B, and the claw 22 is inserted into the opening 33 from the outside.

In the engaging portion 41, the claw 22 is locked to the edge portion of the opening 33 when the fixed portion 40 is disengaged in a state where the internal space 14 is expanded, for example, when the fixing portion 40 is disengaged due to the expansion of the cell 50. As a result, even if the fixing portion 40 is disengaged, the connected state of the first case 20 and the second case 30 is maintained. The protruding length of the claw 22 is set to a length that is firmly hooked on the edge of the opening 33 and does not easily come off. For example, the protruding length of the claw 22> the thickness of the tongue piece portion 32, and the claw 22 protrudes inside the case beyond the inner surface of the tongue piece portion 32.

The claw 22 has a front end that is hooked on the edge of the opening 33 and a rear end that is opposite the front end. The front end portion of the claw 22 is formed, for example, substantially perpendicular to the inner surface of the side surface portion 20B. In this case, the claw 22 is likely to be caught on the edge of the opening 33. On the other hand, the rear end portion of the claw 22 is inclined so that the claw 22 has a tapered shape, for example. When the first case 20 and the second case 30 are overlapped with each other, the rear end of the claw 22 comes into contact with the tip of the tongue piece 32, gets over the tip of the tongue piece 32, and is inserted into the opening 33. Will be done. Therefore, by making the rear end portion of the claw 22 a slope, the claw 22 can be smoothly inserted into the opening 33.

As described above, the tongue piece portion 32 extends forward from the end of the side surface portion 30B and is arranged along the inner surface of the side surface portion 20B. The opening 33 is long in the anteroposterior direction in which the tongue piece portion 32 extends, and is formed in a size such that the claw 22 can move in the anterior-posterior direction in the opening 33. The anteroposterior length of the opening 33 is, for example, 1.5 to 5 times the anteroposterior length of the claw 22. On the other hand, the vertical length of the opening 33 is preferably close to the vertical length of the claw 22 within the range in which the claw 22 can be inserted into the opening 33.

In the present embodiment, the claw 22 is located on the rear end side of the opening 33 in a state where the cell 50 is not inflated. Then, there is a predetermined gap between the front end of the claw 22 and the front end of the opening 33. The length L along the front-rear direction of this gap serves as an expansion allowance for the battery case 13 when the cell 50 expands and the fixed portion 40 comes off. If the length L is too short, it is assumed that the engaging portion 41 is broken by the force due to the expansion of the cell 50. On the other hand, if the length L is too long, the battery case 13 will open wide, and it is necessary to set an appropriate length in consideration of these points. An example of a suitable length L is 1 to 30 mm.

It is preferable that the first case 20 is provided with an extension portion 23 that extends to the side of the second case 30 and overlaps with the second case 30 to hide the internal space 14 in a state where the internal space 14 is expanded. The extending portion 23 is formed at least at the end portion of the side surface portion 20B, and is formed, for example, with a constant width from the upper end portion to the lower end portion of the side surface portion 20B along the vertical direction. The extending portion 23 may be further formed at the ends of the upper surface portion 20C and the lower surface portion 20D, or may be formed in a frame shape so as to surround the opening of the first case 20.

The length of the extending portion 23 in the front-rear direction is, for example, substantially the same as the length L which is the expansion allowance of the battery case 13. In this case, when the cell 50 expands and the battery case 13 expands in the front-rear direction, the exposure of the internal space 14 can be prevented. The length of the extending portion 23 in the front-rear direction may be longer than the length L. The extending portion 23 is formed on the outer side of the case so as not to interfere with the tongue piece portion 32 on the side surface portion of the battery case 13.

The extending portion 23 may extend so as to cover the outer surface of the second case 30, but is preferably inserted into the wall of the second case 30. In the present embodiment, the groove 34 is formed at the end of the side surface portion 30B of the second case 30. When the extending portion 23 is formed in a frame shape surrounding the opening of the first case 20, a groove 34 into which the extending portion 23 is inserted is also formed at the ends of the upper surface portion 30C and the lower surface portion 30D. Is preferable.

6 is a side view of the battery 10, FIG. 7 is a lateral sectional view of the battery 10 (cell 50 and the like are not shown), and FIG. 8 is an enlarged view of the engaging portion 41. 13 indicates an enlarged state.

As shown in FIGS. 6 to 8, when the cell 50 housed in the internal space 14 of the battery case 13 expands significantly, the fixed portion 40 is disengaged and the battery case 13 expands in the front-rear direction. FIG. 7 shows a case where the boss portion 21 is broken due to the expansion of the cell 50 and the fixing by the fixing portion 40 is released. As described above, the engaging portion 41 is configured such that when the fixing portion 40 is disengaged due to the expansion of the cell 50, the claw 22 is caught by the edge portion of the opening 33 and locked.

The engaging portion 41 has a gap of length L between the front end of the claw 22 and the front end of the opening 33 in a state where the cell 50 is not expanded. Therefore, the battery case 13 can be expanded by the length L in the front-rear direction, and when the cell 50 expands, the claw 22 moves from the rear to the front of the opening 33, and the front end of the claw 22 has the opening 33. It is hooked on the front end and locked. By setting this length L to an appropriate range, the battery case 13 can be expanded to the extent that the cell 50 is not largely exposed, and the connected state of the first case 20 and the second case 30 can be maintained.

Further, since the first case 20 is provided with an extension portion 23 that overlaps with the second case 30, when the battery case 13 expands in the front-rear direction, the extension portion 23 causes the extension portion 23 to become the first case 20. The gap of the second case 30 is covered, and the exposure of the internal space 14 is suppressed. In the present embodiment, as the battery case 13 expands, the entire extension portion 23 comes out of the groove 34, and the extension portion 23 covers the periphery of the internal space 14.

The battery case 13 is preferably configured so as not to fit into the charger and the battery mounting portion 12 when the cell 50 is expanded and the internal space 14 is expanded. The lower part of the battery case 13 is inserted into the charger and the battery installation unit 12, but the case may be expanded to a state where this insertion is not possible. In this case, it is possible to prevent the battery 10 from being used continuously. Specifically, the length L, which is an expansion allowance, is set so that the length in the front-rear direction of the battery case 13 is longer than the length of the portion where the case of the charger and the battery installation portion 12 is inserted.

Alternatively, the battery case 13 may be configured to fit into the charger and the battery mounting portion 12 even when the cell 50 is expanded and the internal space 14 is expanded. It is assumed that the battery case 13 expands while the battery 10 is installed in the charger or the battery installation unit 12, but in this case, the restraint on the lower part of the case is relaxed, so that the expansion of the case becomes smooth. .. In order to prevent continuous use of the battery 10, it is preferable to separately provide a means for prohibiting charging / discharging of the cell 50 triggered by the expansion of the battery case 13.

As described above, according to the battery 10 having the above configuration, when the cell 50 housed in the internal space 14 of the battery case 13 is greatly expanded, the first case 20 and the second case 30 are separated into cases. Can be suppressed from opening wide. Even if the cell 50 is greatly expanded and the fixing portion 40 is disengaged, the engaging portion 41 maintains the connected state of the two cases while allowing the expansion of the internal space 14. Therefore, damage to the battery case 13 such that the cell 50 is largely exposed is suppressed. Further, according to the battery case 13, it is not necessary to provide an extra space in the case for absorbing the expansion of the cell 50, and the battery 10 can be miniaturized.

The design of the above embodiment can be appropriately changed as long as the object of the present disclosure is not impaired. For example, in the above embodiment, the claw 22 which is a convex portion is formed in the first case 20, and the opening 33 which is a receiving portion of the convex portion is formed in the second case 30, but the convex portion is formed in the second case 30. A receiving portion may be formed in the first case 20. Further, in the above embodiment, the extension portion 23 is formed only in the first case 20, but the extension portion may be formed in both of the two cases.

FIG. 9 is a diagram showing a battery case 60, which is another example of the embodiment, and shows an enlarged view of the fixing portion 61 and the engaging portion 62. The battery case 60 shown in FIG. 9 is common to the battery case 13 in that the two cases are fixed by using the screws 63. A boss portion 64 is formed in the first case, and a tubular screw insertion portion 65 is formed in the second case, and the screw 63 inserted in the cylinder of the screw insertion portion 65 is fastened to the boss portion 64. Two cases are fixed. On the other hand, the battery case 60 is different from the battery case 13 in that one screw insertion portion 65 is provided with a fixing portion 61 and an engaging portion 62.

In the example shown in FIG. 9, the fixing portion 61 is formed in the intermediate portion of the screw insertion portion 65 away from the tip of the screw insertion portion 65. As shown in FIG. 9A, the fixing portion 61 is a convex portion protruding inward from the inner peripheral surface of the screw insertion portion 65, and locks the head of the screw 63. Similarly, the engaging portion 62 is a convex portion protruding inward from the inner peripheral surface of the screw inserting portion 65, and is formed on the tip end side of the screw inserting portion 65 with respect to the fixing portion 61. As shown in FIG. 9B, when the fixing portion 61 is broken due to the expansion of the cell 50, the head of the screw 63 is caught by the engaging portion 62 and locked.

According to the battery case 60, when the fixed portion 61 is disengaged due to the expansion of the cell 50, the internal space 14 is expanded more than the state fixed by the fixed portion 61 due to the function of the engaging portion 62. The connected state of the case is maintained. In this case, the distance between the fixing portion 61 and the engaging portion 62 in the cylinder of the screw inserting portion 65 serves as an expansion allowance for the battery case 60.

In addition, two openings arranged in the front-rear direction may be formed in the tongue piece portion 32, and the rear opening may form a fixing portion and the front opening may form an engaging portion. Alternatively, two types of tongue pieces are provided, each of which has a first opening and a second opening (length in the front-back direction: first opening <second opening) having different lengths in the front-rear direction, and the first opening serves as a fixed portion. , The second opening may each constitute an engaging portion.

FIG. 10 is a diagram showing a battery case 70, which is another example of the embodiment, and shows an enlarged connection portion between the first case 71 and the second case 72. FIG. 10A shows a normal state in which the internal pressure of the battery case 70 does not rise, and FIG. 10B shows a state in which the internal pressure of the battery case 70 rises and gas is exhausted from the case.

As shown in FIG. 10, the battery case 70 is provided with an exhaust portion 73 that elastically deforms outward to open the internal space 14 when the pressure in the internal space 14 rises and exceeds a predetermined threshold value. ing. In the example shown in FIG. 10, the exhaust unit 73 is provided in the first case 71, but may be provided in both cases.

When an abnormality occurs in the cell 50, it is assumed that gas is ejected from the cell 50 into the battery case 13 and the internal pressure rises. However, according to the battery case 70, the gas from the exhaust unit 73 in such a case. The damage of the case can be suppressed by letting go. Further, the exhaust unit 73 opens to the outside to exhaust the gas, then returns to the original shape and closes the internal space 14, so that the inflow of air into the battery case 70 can be suppressed, and the cell 50 is ignited and continuously. Burning can be prevented.

The exhaust portion 73 is, for example, an end portion of the first case 71 and is formed in a part of a connection portion with the second case 72. A plurality of exhaust units 73 may be provided. The exhaust portion 73 is a portion where the wall thickness of the case is thinner than the other portions, and is preferentially deformed when the internal pressure of the battery case 70 rises. Further, it is preferable that the exhaust portion 73 has flexibility and is elastically deformable.

In the example shown in FIG. 10, the tip portion of the exhaust portion 73 overlaps the outside of the second case 72. In this case, since the exhaust portion 73 is supported from the inside of the case by the second case 72, the strength of the exhaust portion 73 against external force is increased. Further, a recess 74 into which the tip end portion of the exhaust portion 73 fits is formed at the end portion of the second case 72. By fitting the tip of the exhaust portion 73 into the recess 74, the outer surface of the case becomes flat and the closedness of the internal space 14 is improved.

1 Electric assisted bicycle, 2 frame, 2a head pipe, 2b front fork, 2c down pipe, 2d seat pipe, 2e chain stay, 2f seat stay, 3a front wheel, 3b rear wheel, 4 handle, 5 saddle, 6 crank arm, 7 Pedal, 8 chain, 9 headlight, 10 battery, 11 motor unit, 12 battery installation part, 13 battery case, 20 first case, 20A front part, 20B, 30B side part, 20C, 30C top surface part, 20D, 30D Bottom surface, 21 boss, 22 claws, 23 extension, 24 convex, 25 handle, 30 second case, 30A rear surface, 31 screw insertion part, 32 tongue piece part, 33 opening, 34 groove, 40 fixing part , 41 Engagement, 42 Screws, 50 Cell, 51 Protective Board

Claims (5)

A battery case including a first case and a second case having openings, respectively, in which an internal space for accommodating a cell is formed by superimposing the first case and the second case.
A fixing portion for fixing the first case and the second case,
An engaging portion that maintains a connected state between the first case and the second case in a state where the internal space is expanded more than the state fixed by the fixing portion.
Equipped with a battery case. According to claim 1, the first case is provided with an extension portion that extends toward the second case side, overlaps with the second case, and hides the internal space in a state where the internal space is expanded. Described battery case. The engaging portion is
The convex portion formed on one of the first case and the second case,
A receiving portion formed on the other of the first case and the second case into which the convex portion is inserted, and a receiving portion.
The battery case according to claim 1 or 2, wherein the convex portion is locked to the receiving portion in a state where the internal space is expanded. At least one of the first case and the second case is provided with an exhaust portion that elastically deforms outward to open the internal space when the pressure in the internal space exceeds a predetermined threshold value. , The battery case according to any one of claims 1 to 3. The battery case according to any one of claims 1 to 4, and the battery case.
The cell housed in the battery case and
It is a battery for electrically power assisted bicycles equipped with
The battery case is a battery for an electrically assisted bicycle, which is configured so as not to fit into a charger and a battery installation portion of the electrically assisted bicycle when the internal space is expanded.

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