Pressure relief valve for energy storage device

Abstract

Provided is a pressure relief valve for a power storage device, the pressure relief valve configured so as to be easily made compact by keeping the axial direction length thereof short. This pressure relief valve 10 for a power storage device comprises: a housing 15; a valve element 60; and a biasing spring 5. The housing 15 has a first seal surface 28 abutting against a peripheral edge part of a case opening 3. The valve element 60 has a second seal surface 82a abutting against a peripheral edge part of a vent 44. The biasing spring 5 is arranged between the housing 15 and the valve element 60. The housing 15 is fixed to the case opening 3. In a state where the vent 44 has been closed off with the valve element 60, the first seal surface 28 and the second seal surface 82a are arranged between one end 5a and another end 5b of the biasing spring 5 when viewed from a direction orthogonal to the axial direction of the valve element 60.

Description

Technical Field

[0001] The present invention relates to a pressure relief valve for a power storage device that is attached to a case in which a power storage device is housed and releases the pressure inside the case.

Background Art

[0002] For example, in hybrid vehicles and electric vehicles, power storage devices such as batteries and capacitors are used, and these power storage devices are housed and arranged in a case installed inside the vehicle. And when the power storage device is a battery such as a lithium ion battery, for example, gas may be generated by a chemical reaction of the electrolytic solution, and the pressure inside the case may increase. In this case, in order to reduce the pressure inside the case, a pressure relief valve is attached to the case opening.

[0003] For example, Patent Document 1 below describes a pressure regulating valve that is installed in a housing and regulates its internal pressure, and includes a pressure regulating portion that discharges the gas in the housing when the internal pressure is equal to or higher than a certain pressure to regulate the pressure, and a cover portion that contacts the housing and maintains the pressure regulating portion in a sealed state.

[0004] The pressure regulating portion has a base portion attached to the opening of the housing. This base portion has a cylindrical portion provided with a leg portion inserted and fixed into the opening of the housing and a bearing portion disposed inside thereof, and an annular valve seat portion extending from the upper outer periphery of the cylindrical portion. The space between the back side of the valve seat portion and the front side of the housing is sealed by an O-ring. On the other hand, the cover portion has a shaft portion and an umbrella-shaped portion, and an O-ring is fixed to the back side of the umbrella-shaped portion. Further, the shaft portion is inserted and supported by the bearing portion of the cylindrical portion of the base portion, and a spring is disposed on its outer periphery. The upper end of this spring is supported by the bearing portion of the base portion, while the lower end is supported by a stopper fixed to the lower end of the shaft portion of the cover portion.

[0005] In the above pressure regulating valve, normally, the cover part is biased by the spring, the O-ring on the back side of the umbrella-shaped part abuts against the front side of the valve seat part, and the upper opening of the cylindrical part of the base part is blocked (see FIG. 1 of Patent Document 1). In this state, O-rings are arranged on both the front and back sides of the valve seat part across the valve seat part, and the upper end of the spring overlaps the O-ring on the back side of the valve seat part. When the pressure inside the housing rises, against the biasing force of the spring, the umbrella-shaped part rises, the O-ring on its back side separates from the front side of the valve seat part, and the upper opening of the cylindrical part of the base part opens (see FIG. 2 of Patent Document 1).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] In the case of the pressure regulating valve of the above Patent Document 1, when the cover part is closed, as shown in FIG. 1 of Patent Document 1, since two O-rings are arranged on both the front and back sides of the valve seat part, the axial length of the pressure regulating valve becomes relatively large, the pressure regulating valve becomes large in the axial direction, and restrictions are likely to occur in the mounting location of the pressure regulating valve.

[0008] Therefore, an object of the present invention is to provide a pressure relief valve for a power storage device that can suppress the axial length to be small and is easily made compact in the axial direction.

Means for Solving the Problems

[0009] In order to achieve the above object, the present invention provides a pressure relief valve for a power storage device, which is attached to a case in which the power storage device is housed, and is inserted and fixed into a case opening formed in the case, and communicates the internal space and the external space of the case. A vent hole, and a housing having a valve seat provided at its peripheral portion; a valve body slidable with respect to the housing and opening and closing the vent hole; and a biasing spring biasing the valve body toward the valve seat. The housing has a first sealing surface that abuts against a peripheral portion of the case opening, the valve body has a second sealing surface that abuts against a peripheral portion of the vent hole, and the biasing spring is disposed between the housing and the valve body, one end of which is supported by the housing and the other end presses the valve body. The housing is fixed to the case opening, and when viewed from a direction orthogonal to the axial direction of the valve body in a state where the vent hole is closed by the valve body, the first sealing surface and the second sealing surface are configured to be disposed between one end and the other end of the biasing spring.

Advantages of the Invention

[0010] According to the present invention, in a state where the housing is fixed to the case opening and the vent hole is closed by the valve body, when viewed from a direction orthogonal to the axial direction of the valve body, the first sealing surface and the second sealing surface are disposed between one end and the other end of the biasing spring. Therefore, in the axial direction of the valve body, the first sealing surface and the second sealing surface overlap with the biasing spring, so that the length of the pressure relief valve in the valve axis direction (the direction along the axial direction of the valve body) can be kept small, and the pressure relief valve can be made compact in the valve axis direction.

Brief Description of the Drawings

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Mode for Carrying Out the Invention

[0012] (One Embodiment of the Pressure Relief Valve for the Storage Device) Hereinafter, with reference to the drawings, one embodiment of the pressure relief valve for the storage device according to the present invention will be described.

[0013] As shown in FIGS. 10 and 11, this pressure relief valve 10 for the storage device (hereinafter, also simply referred to as "relief valve 10") is attached to a case 1 in which a storage device (not shown) is housed, and when the pressure inside the case rises, it is for releasing (lowering) that pressure.

[0014] Examples of the energy storage device include batteries (such as lithium-ion batteries), capacitors, and capacitators, which are used in hybrid vehicles including plug-in hybrid vehicles and electric vehicles. However, any device capable of storing electrical energy is acceptable and not particularly limited.

[0015] As shown in FIG. 1, a case opening 3 in the shape of a circular hole is formed in wall portions such as the ceiling wall and side walls of the case 1. Further, as shown in FIG. 10, the internal space of the case 1 (the space below in FIG. 10 with the wall portion of the case 1 as the boundary) is defined as the case internal space R1, and the external space of the case 1 (the space above in FIG. 10 with the wall portion of the case 1 as the boundary) is defined as the case external space R2.

[0016] As shown in FIG. 10, in this embodiment, the relief valve 10 is inserted into and fixed to the case opening 3, and has a housing 15 having a vent hole 44 that communicates the case internal space R1 and the case external space R2, and a valve seat 45 provided at its peripheral edge. The relief valve 10 also has a valve body 60 that is slidable relative to the housing 15 and opens and closes the vent hole 44, and a biasing spring 5 that biases the valve body 60 toward the valve seat 45.

[0017] As shown in FIG. 10, the housing 15 has a first sealing surface 28 that abuts against the peripheral edge of the case opening 3. The valve body 60 has a second sealing surface 82a that abuts against the peripheral edge of the vent hole 44. The biasing spring 5 is disposed between the housing 15 and the valve body 60, with one end 5a supported by the housing 15 and the other end 5b configured to press the valve body 60.

[0018] Further, as shown in FIGS. 1 and 10, the housing 15 of this embodiment has a first seal surface 28 that abuts against the peripheral edge of the case opening 3, a first seal member 20 fixed to the case opening 3, a cover member 30 that is mounted outside the first seal member 20 and covers the portion disposed on the front side of the case opening 3 of the first seal member 20, and a base member 40 that is inserted and disposed inside the cover member 30 and the first seal member 20 and temporarily engages and permanently engages with the first seal member 20, and a cap member 50 mounted on the base member 40.

[0019] Further, as shown in FIG. 7, in this embodiment, the first assembly 16 is formed by assembling four components: the cap member 50, the valve body 70, the second seal member 80, and the biasing spring 5. Also, as shown in FIG. 8, the second assembly 17 is formed by further assembling the base member 40 to the first assembly 16, and the third assembly 18 is formed by assembling the first seal member 20 and the cover member 30. Note that the biasing spring 5 in this embodiment is a coil spring formed by winding a wire rod having a predetermined diameter with a predetermined pitch.

[0020] In the following description, unless otherwise specified, the "back side" and "rear surface side" of each member of the housing 15 and each member of the valve body mean the side close to the case 1, and the "front side" and "front surface side" mean the side opposite to the "back side" and "rear surface side" (the side away from the case 1). Also, in the following description, as shown in FIG. 9, the insertion direction F of the relief valve 10 into the case opening 3 is simply referred to as the "insertion direction". The "insertion direction of the housing into the case opening" in the present invention is also the "insertion direction F" in the same manner. Note that the insertion direction of the first assembly 16 with respect to the base member 40 shown in FIG. 7 and the insertion direction of the second assembly 17 with respect to the third assembly 18 shown in FIG. 8 are also the "insertion direction F" in the same manner.

[0021] First, referring to FIGS. 1 and 8, the first seal member 20 will be described.

[0022] The first seal member 20 of this embodiment is formed of an elastic material such as rubber or elastic elastomer, and has a substantially cylindrical main body portion 21. The peripheral wall 41 of the base member 40 is inserted and disposed inside the main body portion 21 in the radial direction (see FIG. 9). An annular thin-walled flange-shaped seal flange portion 22 that elastically contacts the front peripheral edge of the case opening 3 extends from the outer periphery of the base end portion (the end portion on the insertion direction F side) of the main body portion 21. Further, a pressing portion 23 having an annular protrusion shape protrudes from the outer periphery of the main body portion 21 on the tip side in the axial direction rather than the seal flange portion 22. As shown in FIG. 8, the cover member 30 is attached to the outside of the first seal member 20 by sandwiching the locking portion 34a of the cover member 30 between the seal flange portion 22 and the pressing portion 23.

[0023] Furthermore, a retaining portion 25 that can be elastically deformed extends obliquely inward from the base end portion of the main body portion 21 in the insertion direction F. An engaging portion 25a that engages with the rear peripheral edge of the case opening 3 is provided on the outer periphery of the retaining portion 25. Further, as shown in FIG. 10, in a state where the engaging portion 25a of the retaining portion 25 engages with the rear peripheral edge of the case opening 3, the base end portion 25b in the extending direction abuts against the inner peripheral edge of the case opening 3. Further, an annular protrusion-shaped temporary engaging portion 26 and a main engaging portion 27 protrude from the inner periphery of the tip end portion and the inner periphery of the base end portion of the main body portion 21.

[0024] Then, as shown in FIG. 9, the engaging portion 46 of the base member 40 engages with the temporary engaging portion 26, so that the base member 40 is temporarily engaged with the first seal member 20 so as not to be located inside the retaining portion 25. In this state, the retaining portion 25 can be elastically deformed inward in the radial direction of the first seal member 20 and can be inserted into the case opening 3.

[0025] From the above state, as shown in the insertion direction F in FIG. 9, when the first seal member 20 is inserted from the front side of the case opening 3, the seal flange portion 22 abuts against the peripheral edge portion on the front side of the case opening 3, and the engaging portion 25a engages with the peripheral edge portion on the back side of the case opening 3. Further, the base end portion 25b of the retaining portion 25 abuts against the inner peripheral edge portion of the case opening 3 (see FIG. 10). That is, the back surface of the seal flange portion 22, the opposing surface of the engaging portion 25a with the peripheral edge portion on the back side of the case opening 3, and the outer surface of the base end portion 25b of the retaining portion 25 form a first seal surface 28 that abuts against the peripheral edge portion of the case opening 3. In addition, the first seal surface 28 in this embodiment is such that the back surface of the seal flange portion 22 and the opposing surface of the engaging portion 25a with the peripheral edge portion on the back side of the case opening 3 are parallel to each other, and the outer surface of the base end portion 25b of the retaining portion 25 is orthogonally arranged with respect to these two surfaces, so it is substantially U-shaped (see FIG. 8).

[0026] Furthermore, from the above state, when the base member 40 is pushed into the insertion direction F with respect to the first seal member 20, as shown in FIG. 10, the base member 40 is positioned inside the retaining portion 25, restricting the bending deformation of the retaining portion 25 inward, and the engaging portion 46 of the base member 40 engages with the main engaging portion 27. As a result, the first seal member 20 and the base member 40 are main-engaged, and the first seal member 20 and the base member 40 are fixed to the case opening 3.

[0027] Next, with reference to FIGS. 3 and 8, the cover member 30 will be described.

[0028] The cover member 30 of this embodiment has an outer peripheral wall 31 having a substantially cylindrical shape. Inside this outer peripheral wall 31 and on the tip side in the thickness direction of the cover member 30 (the end portion away from the case 1 and opposite to the insertion direction F), an inner peripheral wall 32 having an axial length shorter than that of the outer peripheral wall 31 is connected via a ceiling wall 31a. Inside the inner peripheral wall 32 in the radial direction, the ceiling plate 52 of the cap member 50 is inserted and arranged (see FIG. 10). Further, a plurality of connecting portions 33 having a substantially L shape extend from the base end of the inner peripheral wall 32. A gap 33a is defined among the above-mentioned outer peripheral wall 31, ceiling wall 31a, inner peripheral wall 32, and connecting portion 33. This gap 33a communicates with the internal space (the space on the radially inner side) of the cover member 30.

[0029] Furthermore, inside the outer peripheral wall 31 and on the base end side in the thickness direction of the cover member 30 (the end portion close to the case 1 and on the insertion direction F side), an annular portion 34 having an annular shape is arranged, and this annular portion 34 is connected to and supported by the above-mentioned plurality of connecting portions 33. Note that the main body portion 21 of the first seal member 20 can be inserted inside the annular portion 34 in the radial direction. Further, a lower opening 35 that opens in a direction close to the case opening 3 is formed between the annular portion 34 and the base end portion of the outer peripheral wall 31, and it communicates with the gap 33a. Therefore, the external space and the internal space of the cover member 30 communicate with each other through the gap 33a and the lower opening 35.

[0030] Also, a plurality of locking portions 34a having ridges project from the inner circumference of the annular portion 34 at equal intervals in the circumferential direction (here, three). As shown in FIG. 8, the seal flange portion 22 abuts against the back side of each locking portion 34a, and the pressing portion 23 locks to the front side. By sandwiching each locking portion 34a between the first seal flange portion 22 and the pressing portion 23, the cover member 30 is mounted on the outside of the first seal member 20.

[0031] Further, a slit 36a having a substantially U-shape is formed in the inner peripheral wall 32 and the ceiling wall 31a, and a plurality of deflectable cap pressing pieces 36 are provided at predetermined intervals in the circumferential direction of the inner peripheral wall 32 via the slit 36a (here, four). As shown in FIG. 2, these cap pressing pieces 36 are engaged with the stepped portion 52a of the cap member 50 to hold down the protrusion of the cap member 50 from the upper opening of the cover member 30 (the opening inside the inner peripheral wall 32).

[0032] Next, with reference to FIGS. 4 and 7, the base member 40 will be described.

[0033] The base member 40 of this embodiment has a peripheral wall 41 having a substantially cylindrical shape, and a tip portion 43 having an annular flange shape is provided radially inward from the inner periphery of the tip end in the extending direction of the peripheral wall 41. The peripheral wall 51 of the cap member 50 is inserted and disposed inside the radial direction of the peripheral wall 41 (see FIG. 8). The tip portion 43 forms the "tip portion of the housing in the insertion direction into the case opening" in the present invention. Further, the outer surface of the tip portion 43, that is, the surface close to the case 1 and facing the insertion direction F side forms an end surface 43a.

[0034] Furthermore, a circular vent hole 44 is formed radially inside the tip portion 43, and a valve seat 45 having an annular protrusion shape projects from the outer peripheral edge portion of the vent hole 44 on the inner surface side of the tip portion 43. As shown in FIGS. 10 and 11, the second seal surface 82a of the second seal member 80 externally mounted on the valve body 60 comes into contact with and separates from the valve seat 45 to open and close the vent hole 44.

[0035] In addition, an engaging portion 46 having an annular protrusion shape projects from the outer periphery of the peripheral wall 41 at an intermediate position in the axial direction. By engaging the engaging portion 46 with the temporary engaging portion 26 of the first seal member 20, the base member 40 is held in a temporarily engaged state with respect to the first seal member 20 (see FIG. 9), and by engaging with the main engaging portion 27 of the first seal member 20, the first seal member 20 and the base member 40 are main-engaged (see FIG. 10).

[0036] Furthermore, a plurality (here, four) of locking pieces 47 are erected at predetermined intervals in the circumferential direction from the end face of the tip portion in the extending direction of the peripheral wall 41 (the end portion away from the case 1 and on the side opposite to the insertion direction F). Each locking piece 47 is formed with a locking hole 47a having an elongated hole shape. As shown in FIG. 8, the locking piece 56 of the cap member 50 is locked to the locking hole 47a, so that the cap member 50 is attached to the base member 40. Further, a ridge portion 47b projects from the outer periphery of the tip portion of each locking piece 47 in the erected direction, facilitating the gripping of the base member 40 when attaching the cap member 50 to the base member 40.

[0037] Next, the cap member 50 will be described with reference to FIGS. 1, 5, and 7.

[0038] The cap member 50 of this embodiment has a peripheral wall 51 having a substantially cylindrical shape and a ceiling plate 52 having a substantially disc shape connected to one end of the peripheral wall 51. Further, the ceiling plate 52 projects a predetermined length from the outer periphery of the peripheral wall 51, and a stepped portion 52a having a stepped shape is formed at the outer peripheral edge portion thereof. The cap pressing piece 36 of the cover member 30 can be locked to the stepped portion 52a (see FIG. 2), restricting the protrusion of the cap member 50 from the upper opening of the cover member 30.

[0039] Also, a circular opening 53a is formed at the radial center of the ceiling plate 52. From the rear peripheral edge of this opening 53a, a cylindrical portion 53 having a substantially cylindrical shape extends with a length shorter than the axial length of the peripheral wall 51. Inside the cylindrical portion 53 in the radial direction, the shaft portion 72 of the valve body 70 is inserted and arranged so as to be axially slidable. On the outside of the cylindrical portion 53 in the radial direction, a biasing spring 5 is externally mounted (see FIGS. 10 and 11). And on the back side of the ceiling plate 52, a spring support portion 54 that supports one end 5a of the biasing spring 5 is formed at the outer peripheral edge portion of the base end portion of the cylindrical portion 53 (see FIG. 7). Further, the opening 53a located on the base end side in the extending direction of the cylindrical portion 53 forms the other end opening of the cylindrical portion 53 opposite to one end facing the valve body 60 side. As shown in FIG. 11, when the valve body 60 opens from the vent hole 44, the tip portion in the extending direction of the cylindrical portion 53 abuts against the spring support portion 73 of the valve body 70, and the opening amount of the valve body 60 with respect to the vent hole 44 is regulated.

[0040] Furthermore, a valve locking portion 55 projects from the inner circumference of the tip portion in the extending direction of the cylindrical portion 53. As shown in FIG. 7, by locking the locking projection 76 of the valve body 60 to the inner surface of this valve locking portion 55, the valve body 60 is prevented from coming off from the cap member 50. Further, a pair of notches 55a, 55a are formed at positions facing each other in the radial direction of the valve locking portion 55 (see FIG. 5).

[0041] Also, a slit 56a having a substantially U-shape is formed in the peripheral wall 51. Through this slit 56a, a plurality of locking pieces 56 that can be elastically deformed are provided at predetermined intervals in the circumferential direction of the peripheral wall 51 (here, four). By each locking piece 56 locking to the corresponding locking hole 47a of the base member 40, the cap member 50 is attached to the base member 40 (see FIG. 8).

[0042] Furthermore, in the peripheral wall 51, a plurality of laterally opening portions 57 each having a substantially rectangular shape are formed at predetermined intervals in the circumferential direction between the locking pieces 56, 56 adjacent to each other in the circumferential direction (here, four). Each laterally opening portion 57 communicates the external space and the internal space of the peripheral wall 51 with each other. Also, on the back surface side of the ceiling plate 52, rib portions 58 each having a thin and long plate shape extend radially from the radial center thereof toward the outer peripheral edge portion (see FIG. 5), and the rigidity of the ceiling plate 52 is improved.

[0043] Next, with reference to FIGS. 1, 6, and 7, the valve body 60 will be described.

[0044] The valve body 60 of this embodiment has a valve main body 70 and a second seal member 80 attached to the outer periphery of the valve main body 70. Note that the second seal member 80 forms the "seal member" in the present invention.

[0045] The valve main body 70 has a base portion 71 having a circular outer periphery and a stepped cross section, and a shaft portion 72 having a substantially cylindrical shape that extends from the radial center thereof by a predetermined length on the surface side of the base portion 71.

[0046] The base portion 71 has a spring support portion 73 that supports the other end 5b of the biasing spring 5, an enlarged diameter portion 74 that expands from the outer peripheral edge portion of the spring support portion 73 via a stepped portion 74a, and an outer peripheral edge portion 75 that spreads from the outer peripheral edge portion of the enlarged diameter portion 74 via a stepped portion 75a. The surface of the spring support portion 73 forms a support surface 73a that supports the other end 5b of the biasing spring 5. Note that the surface 73b on the side opposite to the support surface 73a forms the "surface on the side opposite to the support surface of the biasing spring of the spring support portion" in the present invention. Also, an annular protrusion 75b that protrudes at a minute height projects from the circumferential edge on the back surface side of the outer peripheral edge portion 75.

[0047] Furthermore, at the tip end portion in the extending direction of the shaft portion 72, a pair of locking protrusions 76, 76 project from positions facing each other in the radial direction. By inserting these pair of locking protrusions 76, 76 into a pair of notches 55a, 55a provided in the cylindrical portion 53 of the cap member 50 and rotating the shaft portion 72 with respect to the cylindrical portion 53, the pair of locking protrusions 76, 76 can be locked to the valve locking portion 55 of the cylindrical portion 53, and the shaft portion 72 is prevented from coming off from the one end opening (the opening on the side opposite to the opening 53a) of the cylindrical portion 53 facing the valve body side. As a result, the valve body 70 is retained against the cap member 50 so as to be slidably prevented from coming off in the axial direction of the valve body 60 via the cylindrical portion 53 and the shaft portion 72.

[0048] Also, as shown in FIG. 11, the shaft portion 72 is configured so as not to protrude from the surface of the housing 15 when the valve body 60 is fully opened from the vent hole 44. More specifically, FIG. 10 shows a state in which the housing 15 is fixed to the case opening 3 and the vent hole 44 of the housing 15 is closed by the valve body 60. From this state, when the pressure in the internal space R1 of the case 1 rises and the valve body 60 is fully opened from the vent hole 44 against the biasing force of the biasing spring 5 as shown in FIG. 11, the tip end portion in the extending direction of the shaft portion 72 is configured so as not to protrude from the surface of the ceiling plate 52 of the cap member 50 constituting the housing 15. Here, when the valve body 60 is fully opened from the vent hole 44, the end face of the tip end portion of the shaft portion 72 substantially coincides with the surface of the ceiling plate 52 of the cap member 50.

[0049] Also, as shown in FIG. 11, in a state where the relief valve 10 is attached to the case 1 (a state where the relief valve 10 is fixed to the case opening 3), when the valve body 60 is fully opened from the vent hole 44, the amount of protrusion T2 of the shaft portion 72 from the case opening 3 (the length from the surface 1a of the wall portion of the case 1 in which the case opening 3 is formed (see the two-dot chain line in FIG. 11) to the end face in the extending direction of the shaft portion 72) is configured not to exceed the maximum amount of protrusion T1 of the housing 15 from the case opening 3 (the length from the surface 1a of the wall portion of the case 1 in which the case opening 3 is formed to the surface of the housing 15, here the surface of the ceiling plate 52 of the cap member 50).

[0050] Furthermore, from a position on the outer periphery of the base end portion in the extending direction of the shaft portion 72, which is orthogonal to the pair of locking protrusions 76, 76, a pair of rotation restricting ribs 77, 77 extending along the extending direction of the shaft portion 72 are provided. These pair of rotation restricting ribs 77, 77 are in a position that aligns with the pair of notches 55a, 55a of the cylindrical portion 53 when the pair of locking protrusions 76, 76 are locked to the valve locking portion 55 of the cylindrical portion 53. As a result, when the valve body 60 slides as shown in FIG. 11, the pair of rotation restricting ribs 77, 77 enter into the pair of notches 55a, 55a, and the rotation of the valve body 60 is restricted.

[0051] On the other hand, the second seal member 80, similar to the first seal member 20, is formed of an elastic material such as rubber or elastic elastomer, for example, and has a cylindrical portion 81 having a substantially cylindrical shape. This cylindrical portion 81 is formed to be larger than the outer diameter of the outer peripheral edge portion 75 of the valve body 70 and is slidably inserted and disposed on the inner periphery of the peripheral wall 51 of the cap member 50 (see FIGS. 10 and 11).

[0052] Also, a seal portion 82 is provided at an end portion of the second seal member 80 facing the vent hole 44 side of the housing 15. Further, a second seal surface 82a is provided on the end surface of this seal portion 82 facing the vent hole 44 side. Specifically, a seal portion 82 protruding annularly inward in the radial direction is provided from the inner periphery of the base end portion (the end portion close to the case 1 and on the insertion direction F side) of the cylindrical portion 81, and the end surface of this seal portion 82 facing the vent hole 44 side (which can also be said to be the surface close to the case 1 and facing the insertion direction F side) forms the second seal surface 82a. And as shown in FIGS. 10 and 11, the second seal surface 82a of the seal portion 82 comes into contact with and separates from the valve seat 45 to open and close the vent hole 44.

[0053] Furthermore, from the inner circumference of the tip of the cylindrical portion 81 (the end portion away from the case 1 and on the side opposite to the insertion direction F), a pressing portion 83 having an annular protrusion shape that protrudes radially inward with a length shorter than that of the seal portion 82 protrudes. An annular groove 84 is formed between the pressing portion 83 and the seal portion 82. By fitting the outer peripheral edge portion 75 of the base portion 71 of the valve body 70 into this annular groove 84, the outer peripheral edge portion 75 is sandwiched between the seal portion 82 and the pressing portion 83, and the second seal member 80 is mounted on the outer circumference of the base portion 71 of the valve body 70 (see FIG. 7).

[0054] In this mounted state, an annular protrusion 75b provided on the back surface side peripheral edge of the outer peripheral edge portion 75 abuts against a part of the surface 82b of the seal portion 82 on the side opposite to the second seal surface 82a (see FIG. 7), so that the sealing performance between the outer peripheral edge portion 75 of the base portion 71 and the seal portion 82 is enhanced. Further, in the state where the second seal member 80 is mounted on the outer circumference of the base portion 71 of the valve body 70, the second seal surface 82a of the seal portion 82 is arranged on the same plane as the back surface of the enlarged diameter portion 74 of the base portion 71 (see FIG. 7).

[0055] Also, as shown in FIG. 10, the surface 73b of the spring support portion 73 constituting the base portion 71, which is opposite to the support surface 73a of the biasing spring 5, is configured not to protrude with respect to the end surface 43a of the tip portion 43 in the insertion direction F of the base member 40 constituting the housing 15 into the case opening 3.

[0056] Next, the relationship among the first seal surface 28, the second seal surface 82a, and the biasing spring 5 in this relief valve 10 will be described.

[0057] That is, in this relief valve 10, as shown in FIG. 10, with the housing 15 fixed to the case opening 3 and the vent hole 44 of the housing 15 closed by the valve body 60, when viewed from a direction orthogonal to the axial direction of the valve body 60 (the direction along the axis C of the valve body 60, which can also be called the valve axis direction), the first seal surface 28 and the second seal surface 82a are configured to be arranged between one end 5a and the other end 5b of the biasing spring 5.

[0058] FIG. 10 shows a cross-sectional view when the valve body 60 is cut parallel to its axial direction (it can be said that it is a cross-section in a direction orthogonal to the axial direction of the valve body 60 and when viewed from a direction orthogonal to the axial direction of the valve body 60). In this case, the biasing spring 5 is arranged in a state where its axial direction is compressed on the outer periphery of the cylindrical portion 53 of the cap member 50 and the outer periphery of the shaft portion 72 of the valve body 70. One end 5a thereof abuts against and is supported by the spring support portion 54 of the cap member 50, and the other end 5b abuts against and supports the support surface 73a of the spring support portion 73 of the valve body 70 and presses the valve body 60, thereby biasing the second seal member 80 mounted on the outer periphery of the valve body 70 toward the valve seat 45 provided on the base member 40 so as to close the vent hole 44 formed in the housing 15.

[0059] And in the state shown in FIG. 10, the first seal surface 28 and the second seal surface 82a are located between one end 5a and the other end 5b of the biasing spring 5 and on the other end 5b side of the biasing spring 5. The thickness direction (the direction along the axial direction of the valve body 60) of the first seal surface 28 and the second seal surface 82a overlaps (laps) with respect to the axial direction of the biasing spring 5.

[0060] Here, the first seal surface 28 is arranged at a position slightly biased toward the one end 5a side from the other end 5b of the biasing spring 5, and the second seal surface 82a is closer to the other end 5b of the biasing spring 5 than the first seal surface 28 and is arranged at a position that aligns with the end surface of the other end 5b of the biasing spring 5. The two seal surfaces 28 and 82a are displaced from each other in the axial direction of the biasing spring 5 (see FIG. 10).

[0061] Further, the first seal surface 28 and the second seal surface 82a are arranged so as to overlap in the axial direction of the biasing spring 5, but are arranged so as to be displaced in the radial direction of the housing 15. That is, as shown in FIG. 10, the second seal surface 82a is arranged on the outer side in the radial direction of the biasing spring 5, and the first seal surface 28 is arranged on the outer side in the radial direction of the second seal surface 82a. The two seal surfaces 28, 82a are arranged so as to be concentric with respect to the axis of the valve body 60, and the two seal surfaces 28, 82a are arranged so as to be displaced in the radial direction of the housing 15.

[0062] In the present invention, the phrase "the first seal surface and the second seal surface are arranged between one end and the other end of the biasing spring" shall include the case where each seal surface is arranged in alignment (coinciding in the axial direction) with the end surface of one end or the other end of the biasing spring.

[0063] (Modification example) In the embodiment described above, the case 1 has a configuration in which a case opening is provided directly in the wall portion. However, as the case, for example, a single or a plurality of recesses may be provided in the wall portion, and a case opening may be formed at the bottom thereof. Further, the shape of the case opening may be rectangular, angular, elliptical, or the like, as long as it is a shape capable of attaching the pressure relief valve.

[0064] Furthermore, the shape and structure of the housing, the first seal member constituting the housing, the cover member, the base member, the cap member, and further the valve body and the valve body main body and the second seal member constituting the valve body are not limited to the above-described aspects.

[0065] For example, the main body portion of the first seal member, the peripheral wall of the cover member, the peripheral wall of the base member, the peripheral wall of the cap member, and the cylindrical portion of the second seal member are all substantially cylindrical, but this portion may be elliptical cylindrical, rectangular cylindrical, or the like.

[0066] In addition, the valve seat 45 provided on the housing 15 has a circular protrusion shape, and correspondingly, the seal portion 82 and the second seal surface 82a are also annular. However, for example, the valve seat, the flange portion, and the second seal surface may be elliptical, rectangular, or the like, as long as the second seal surface can contact and separate from the valve seat to open and close the vent hole.

[0067] Furthermore, the first seal surface 28 in this embodiment is substantially U-shaped, consisting of the back surface of the seal flange portion 22, the opposing surface of the engaging portion 25a with the peripheral edge portion on the back side of the case opening 3, and the outer surface of the base end portion 25b of the retaining portion 25 (see FIG. 8). However, as the first seal surface, for example, it may contact only one location on each of the peripheral edge portions of the front side peripheral edge portion, the back side peripheral edge portion, and the inner side peripheral edge portion of the case opening, or may contact at two locations in an appropriate combination. As long as it contacts the peripheral edge portion of the case opening, its shape is not particularly limited.

[0068] Furthermore, in this embodiment, the housing 15 is composed of a first seal member 20, a cover member 30, a base member 40, and a cap member 50, and each member is separate. However, one or more of these constituent members may be integrally formed. Also, the valve body 60 is composed of a valve main body 70 and a second seal member 80, and each member is separate, but both members may be integrally formed.

[0069] In addition, in the case of this embodiment, (1) the fixing structure between the case opening 3 and the first seal member 20 consists of the seal flange portion 22 and the engaging portion 25a as shown in FIG. 10, (2) the mounting structure between the first seal member 20 and the cover member 30 consists of the seal flange portion 22, the pressing portion 23, and the locking portion 34a as shown in FIG. 8, (3) the temporary engagement structure and the main engagement structure between the first seal member 20 and the base member 40 consist of the temporary engagement portion 26, the main engagement portion 27, and the engaging portion 46 as shown in FIGS. 9 and 10, (4) the mounting structure between the base member 40 and the cap member 50 consists of the locking hole 47a and the locking piece 56 as shown in FIG. 8, and (5) the retaining structure between the cap member 50 and the valve body 60 consists of the valve locking portion 55 and the locking protrusion 76 as shown in FIG. 8. However, these respective structures are not particularly limited.

[0070] For example, as the structure of (2), a concave portion may be provided on the inner circumference of the cover member and a convex portion may be provided on the outer circumference of the first seal member. As the structure of (4), a locking piece may be provided on the base member side and a locking hole may be provided on the cap member side. As the structure of (5), a predetermined number of convex portions may be provided from the inner circumference of the cylindrical portion, and a concave groove into which each convex portion fits may be provided on the outer circumference of the shaft portion.

[0071] Furthermore, in this embodiment, the cylindrical portion 53 is provided on the cap member 50 side and the shaft portion 72 is provided on the valve body 60 side (see FIG. 8). Conversely, a cylindrical portion or a hole may be provided on the valve body side, and a shaft portion that is inserted into the cylindrical portion or the hole and is slidably supported may be provided on the cap member side.

[0072] Also, in this embodiment, the first seal surface 28 is disposed at a position slightly biased toward the one end 5a side rather than the other end 5b of the biasing spring 5, and the second seal surface 82a is disposed at a position that aligns with the end surface of the other end 5b of the biasing spring 5 (see FIG. 10). For example, (1) the first seal surface may be disposed closer to the other end of the biasing spring than the second seal surface, (2) either one or both of the first seal surface and the second seal surface may be disposed at an intermediate position in the axial direction of the biasing spring or on the other end side, or (3) both seal surfaces may be disposed at the same position without being axially displaced, as long as the layout is such that both seal surfaces are disposed between the one end and the other end of the biasing spring. Furthermore, although the radial positional relationship among the first seal surface, the second seal surface, and the biasing spring is not particularly limited, it is preferable that the two seal surfaces do not overlap in the radial direction of the housing and are displaced in position.

[0073] (Function and Effect) Next, the function and effect of the release valve 10 according to the present invention having the above configuration will be described.

[0074] First, the assembly process of the release valve 10 will be described.

[0075] First, fit the outer peripheral edge portion 75 of the valve body 70 into the annular groove 84 of the second seal member 80, and attach the second seal member 80 to the outer periphery of the valve body 70 (see Fig. 7). Then, externally fit the biasing spring 5 onto the cylindrical portion 53 of the cap member 50, and abut and support one end 5a of the biasing spring 5 against the spring support portion 54 of the cap member 50. In this state, align the pair of locking protrusions 76, 76 on the shaft portion 72 of the valve body 70 with the pair of notches 55a, 55a in the cylindrical portion 53 of the cap member 50, push the shaft portion 72 into the cylindrical portion 53, pass each locking protrusion 76 through each notch 55a, and then rotate the shaft portion 72 with respect to the cylindrical portion 53. Then, the pair of locking protrusions 76, 76 are locked to the valve locking portion 55 of the cylindrical portion 53, and the other end 5b of the biasing spring 5 is abutted and supported on the support surface 73a of the spring support portion 73 of the valve body 60. With the biasing spring 5 compressed, the valve body 60 is retained against removal with respect to the cap member 50. In this way, the four components of the cap member 50, the valve body 70, the second seal member 80, and the biasing spring 5 can be assembled to assemble the first assembly 16 as shown in Fig. 7.

[0076] After that, align each locking piece 56 of the cap member 50 constituting the first assembly 16 with the corresponding locking hole 47a of the base member 40, and then push the first assembly 16 into the base member 40 as shown in the insertion direction F in Fig. 7. Then, as shown in Fig. 8, each locking piece 56 is locked to each locking hole 47a, and the cap member 50 is attached to the base member 40, and the second assembly 17 can be assembled.

[0077] Also, insert the main body portion 21 of the first seal member 20 into the annular portion 34 of the cover member 30, and sandwich the locking portion 34a of the cover member 30 with the seal flange portion 22 and the pressing portion 23. As a result, as shown in Fig. 8, the cover member 30 is attached to the outer periphery of the first seal member 20, and the third assembly 18 can be assembled. In this state, the second seal member 80 of the valve body 60 biased by the biasing spring 5 is biased toward the valve seat 45 side, the second seal surface 82a abuts on the valve seat 45, and the vent hole 44 is closed (see Fig. 7).

[0078] Thereafter, as shown by the arrow in Fig. 8, the second assembled body 17 is pushed into the third assembled body 18. That is, the second assembled body 17 is pushed in from the front-side opening of the cover member 30 constituting the third assembled body 18. Then, as shown in Fig. 9, the engaging portion 46 of the base member 40 engages with the temporary engaging portion 26 of the first seal member 20, and the base member 40 is temporarily engaged with the first seal member 20 so that the base member 40 does not locate inside the retaining portion 25 of the first seal member 20. The second assembled body 17 is temporarily held at a relatively shallow insertion position with respect to the third assembled body 18, and the release valve 10 is constituted. In this temporarily held state, the retaining portion 25 is configured to be bendable and deformable inward in the radial direction of the first seal member 20. Note that the release valve 10 in this embodiment is configured to be conveyed in a state where the second assembled body 17 is temporarily held with respect to the third assembled body 18.

[0079] Then, as shown by the arrow F in Fig. 9, the release valve 10 is inserted from the front side of the case opening 3. Then, the retaining portion 25 of the first seal member 20 is pressed against the inner periphery of the case opening 3 and bends and deforms inward of the first seal member 20. Thereafter, the release valve 10 is pushed into the case opening 3 until the seal flange portion 22 of the first seal member 20 abuts against the front-side peripheral edge portion of the case opening 3. When the retaining portion 25 passes through the back-side opening of the case opening 3, the retaining portion 25 elastically returns, and the engaging portion 25a engages with the back-side peripheral edge portion of the case opening 3. As a result, the seal member 20 is temporarily fixed to the case opening 3, and thus the release valve 10 can be temporarily fixed to the case opening 3. Even in this state, the retaining portion 25 is configured to be bendable and deformable inward in the radial direction of the seal member 20.

[0080] From the above state, the base member 40 and the cap member 50 are pushed into the insertion direction F with respect to the first seal member 20. Then, the engaging portion 46 of the base member 40 disengages from the temporary engaging portion 26 of the first seal member 20, and the peripheral wall 41 of the base member 40 enters the inside of the retaining portion 25. The engaging portion 46 engages with the main engaging portion 27, and the peripheral wall 41 presses the retaining portion 25 outward. As a result, as shown in FIG. 10, the engaging portion 25a of the retaining portion 25 strongly engages with the rear peripheral edge portion of the case opening 3, the first seal member 20 is main-engaged with the case opening 3, and thus the release valve 10 can be fixedly attached to the case opening 3. In this fixedly attached state, since the peripheral wall 41 of the base member 40 is disposed inside the retaining portion 25, the inward deflection deformation of the retaining portion 25 in the radial direction is suppressed, its diameter reduction is restricted, and the locking state between the engaging portion 25a and the rear peripheral edge portion of the case opening 3 is maintained. Therefore, the state in which the release valve 10 is fixedly attached to the case opening 3 of the case 1 can be continued.

[0081] Also, in the state shown in FIG. 10, the second seal member 80 of the valve body 60 is biased toward the valve seat 45 by the biasing spring 5 held in a compressed state between the cap member 50 and the valve body 60, and the second seal surface 82a abuts against the valve seat 45 to close the vent hole 44 (see FIG. 7). Further, as shown in FIG. 10, even when the release valve 10 is fixed to the case opening 3, the lower opening 35 formed in the cover member 30 is disposed above the seal flange portion 22, and its open state is maintained (see the broken line in FIG. 10). The external space and the internal space of the cover member 30 are kept in a communicating state with each other.

[0082] When gas is generated in the case due to the power storage device, such as when the power storage device supplies power to a drive source or electrical components, or due to the external environment and internal environment of the case in which the power storage device is housed (for example, when a power storage device such as a lithium-ion battery supplies power by driving a motor or the like, gas is generated by a chemical reaction of the electrolytic solution), the following operation occurs.

[0083] That is, when the pressure in the internal space R1 of the case 1 rises and exceeds the biasing force of the biasing spring 5, the valve body 60 slides in a direction away from the valve seat 45 against the biasing force, and the second sealing surface 82a moves away from the valve seat 45. Then, as shown in FIG. 11, the vent hole 44 of the base member 40 opens, and through this vent hole 44, the internal space R1 of the case 1 communicates with the external space R2.

[0084] As a result, the gas in the internal space R1 of the case 1 flows into the peripheral wall 51 of the cap member 50, passes through the side opening 57 and the slit 56a of the cap member 50, the gap between the locking pieces 47, 47 of the base member 40 (see FIG. 4), and the gap 33a of the cover member 30, and is exhausted from the lower opening 35 of the cover member 30 (see the arrow L in FIG. 11). Therefore, the pressure in the case 1 can be released (reduced).

[0085] And in this relief valve 10, as shown in FIG. 10, the housing 15 is fixed to the case opening 3, and when viewed from a direction orthogonal to the axial direction of the valve body 60 with the vent hole 44 closed by the valve body 60, the first sealing surface 28 and the second sealing surface 82a are configured to be disposed between one end 5a and the other end 5b of the biasing spring 5. Therefore, in the axial direction of the valve body 60, since the first sealing surface 28 and the second sealing surface 82a overlap with the biasing spring 5, the length of the relief valve 10 in the valve axial direction (the direction along the axial direction of the valve body 60) can be kept small, and the relief valve 10 can be made compact in the valve axial direction. As a result, even when there are restrictions on the mounting location of the relief valve 10 in the case 1 (especially when there is a height restriction, etc.), the relief valve 10 can be firmly mounted to the case opening 3.

[0086] Also, in this embodiment, as shown in FIG. 10, the valve body 60 has a spring support portion 73 that supports the other end 5b of the biasing spring 5, and the surface 73b of the spring support portion 73 on the side opposite to the support surface 73a of the biasing spring 5 is configured not to protrude with respect to the end surface 43a of the tip portion 43 of the housing 15 in the insertion direction F into the case opening 3.

[0087] According to the above aspect, while ensuring the thickness of the spring support portion 73 (the length along the valve shaft direction) (thereby maintaining the rigidity of the spring support portion 73 and being able to firmly receive the pressing force of the biasing spring 5), when the valve body 60 closes against the vent hole 44, it is possible to suppress the protrusion of the tip end portion 43 of the valve body 60 in the insertion direction F into the case opening 3 of the housing 15 with respect to the end face 43a, and to further suppress the length of the release valve 10 in the valve shaft direction to be smaller and make it easier to make it compact.

[0088] Furthermore, in this embodiment, the housing 15 has a cylindrical portion 53, the valve body 60 has a shaft portion 72 that is inserted into and supported by the cylindrical portion 53, and the shaft portion 72 is configured not to protrude from the surface of the housing 15 (here, the surface of the ceiling plate 52 of the cap member 50) when the valve body 60 is fully opened from the vent hole 44 (see FIG. 11).

[0089] According to the above aspect, since the shaft portion 72 of the valve body 60 is inserted into and supported by the cylindrical portion 53 of the housing 15, the sliding operation of the valve body 60 can be guided, and when the valve body 60 is fully opened from the vent hole 44, the shaft portion 72 is configured not to protrude from the surface of the housing 15. Therefore, at the time of maximum opening of the valve body 60, the length of the release valve 10 in the valve shaft direction can be further suppressed to be smaller and made more compact.

[0090] Also, in this embodiment, as shown in FIGS. 1 and 10, the valve body 60 has a valve body main body 70 and a seal member (here, the second seal member 80) attached to the outer periphery of the valve body main body 70. An annular groove 84 is formed inside the second seal member 80, and the outer periphery of the valve body main body 70 is fitted into the annular groove 84 so that the second seal member 80 is attached to the outer periphery of the valve body main body 70. A second seal surface 82a is provided on the end face of the second seal member 80 facing the vent hole 44 side.

[0091] According to the above aspect, by fitting the outer periphery of the valve body 70 into the annular groove 84 inside the second seal member 80, the second seal member 80 is mounted on the outer periphery of the valve body 70. Thus, the second seal surface 82a can be easily provided, and the second seal surface 82a is less likely to protrude from the axial end surface of the housing 15 than when the second seal surface is provided on the case opening side. As a result, the valve axial length of the pressure relief valve 10 can be more effectively suppressed, making it easier to achieve compactification.

[0092] (Other embodiments of the pressure relief valve for a power storage device) Figs. 12 to 26 show other embodiments of the pressure relief valve for a power storage device according to the present invention. Note that substantially the same parts as those in the above embodiments are denoted by the same reference numerals, and the description thereof is omitted.

[0093] As shown in Fig. 12, this pressure relief valve 10A for a power storage device (hereinafter also simply referred to as "relief valve 10A") has a housing 15A. This housing 15A is disposed on the side of the external space R2 of the case and has an opening 97 that radially communicates the internal space and the external space of the housing 15A.

[0094] The housing 15A includes a base member 90 having a flexible piece 110, a first seal member 20A mounted on the base end portion side of the base member 90, a cover member 120 mounted on the tip end portion side of the base member 90, a push member 130 that can be pushed into the base member 90 and restricts the inward flexure deformation of the flexible piece 110, a second seal member 80A mounted on the push member 130, and a cap member 140 that supports one end 5a of the biasing spring 5 and pushes the push member 130 via the second seal member 80A.

[0095] Note that the internal space of the housing 15A means the inside bounded by the wall portions of the members constituting the housing 15A that are located on the outermost side (here, the peripheral wall 121 and the ceiling wall 123 of the cover member 120), and this is defined as the housing internal space R3 (see FIGS. 21 to 23). Also, the external space of the housing 15A means the outside bounded by the wall portion of the member located on the outermost side among the constituent members of the housing 15A, and in this embodiment, it is synonymous with the case external space R2.

[0096] Then, as shown in FIG. 18, the first assembly 16A is formed by assembling the two components of the pushing member 130 and the second seal member 80A, and the second assembly 17A is formed by assembling the two components of the base member 90 and the first seal member 20A. Also, as shown in FIG. 19, the third assembly 18A is formed by assembling the first assembly 16A and the second assembly 17A.

[0097] First, referring to FIGS. 14, 18, etc., the base member 90 will be described.

[0098] More specifically, this base member 90 has a cylindrical wall portion 91 having a substantially cylindrical shape, a bottom plate portion 93 having a substantially annular plate shape that projects radially outward from the outer peripheral surface near the tip of the cylindrical wall portion 91, a ceiling plate portion 94 having a substantially annular plate shape and disposed opposite to the bottom plate portion 93 with a predetermined interval therebetween, and a plurality of connecting pieces 95 that connect the two plate portions 93 and 94 to each other. Also, the cylindrical wall portion 91 has a protruding portion 91a that protrudes at a predetermined height from the inner peripheral edge portion of the bottom plate portion 93 toward the ceiling plate portion 94 side.

[0099] Each connecting piece 95 has a plate shape that extends across the plate portions 93 and 94 in the radial direction, and all the connecting pieces 95 extend in the same direction. And the opening 97 is provided between the connecting pieces 95 and 95 adjacent to each other in the circumferential direction, the bottom plate portion 93, and the ceiling plate portion 94.

[0100] Also, between the connecting pieces 95, 95 located at two positions facing each other in the radial direction of the two plate portions 93, 94, first plate-shaped pieces 98 extending in the same direction as each connecting piece 95 are respectively provided. Further, the first plate-shaped pieces 98 and the connecting pieces 95, 95 located on both sides thereof are connected to each other by a second plate-shaped piece 99 disposed at a position closer to the ceiling plate portion 94 and extending across the pieces 95, 98, and these portions form a substantially lattice shape as a whole.

[0101] Also, from the outer surfaces of the pair of connecting pieces 95, 95 arranged orthogonally to the pair of first plate-shaped pieces 98, 98, third plate-shaped pieces 100 orthogonal to the extending direction of the connecting pieces 95 respectively project. Further, fourth plate-shaped pieces 101 project from both sides of the base end portions of each third plate-shaped piece 100.

[0102] Note that the locking claws 128 of the cover member 120 are adapted to lock to the base end surfaces (the back surfaces of the base end portions) of the first plate-shaped pieces 98 and the third plate-shaped pieces 100 (see FIG. 21).

[0103] Also, at the inner peripheral edge portion of the ceiling plate portion 94, at the locations where the first plate-shaped pieces 98 and the second plate-shaped pieces 99 are provided, and at the locations where the third plate-shaped pieces 100 and the fourth plate-shaped pieces 101 are provided, notches 102 are formed to allow the engaging pieces 144 of the cap member 140 to be inserted. Here, four notches 102 are formed at equal intervals in the circumferential direction.

[0104] Also, on the back surface of the ceiling plate portion 94, at the inner peripheral edge portion of the notch 102, engaging claws 145 of the cap member 140 are engaged to temporarily hold the cap member 140 in a state of protruding from the surface of the ceiling plate portion 94 of the base member 90 (see FIG. 20), and a temporary engaging surface 103 is provided.

[0105] Also, on the surface of the outer peripheral edge of the ceiling plate portion 94, positioning protrusions 104 that are inserted into the positioning holes 123a (see FIG. 15) of the cover member 120 project from positions corresponding to the notches 102. Further, guide grooves 105 for guiding the guide ribs 121a of the cover member 120 are respectively formed between the positioning protrusions 104, 104 adjacent in the circumferential direction on the outer peripheral edge of the ceiling plate portion 94.

[0106] Also, on the inner peripheral surface of the second plate-like piece 99, at a position separated from the temporary engagement surface 103, and on the inner peripheral surface of the connecting piece 95 where the third plate-like piece 100 protrudes, main engagement protrusions 106 project from positions at the same height as the second plate-like piece 99.

[0107] The back surfaces of the main engagement protrusions 106 form the main engagement surface 107. As shown in FIG. 23, when the engagement claws 145 of the cap member 140 engage with the main engagement surface 107, the surface of the ceiling plate 141 of the cap member 140 is flush with the surface of the ceiling wall 123 of the cover member 120 (a state where the cap member 140 does not protrude from the ceiling surfaces of the base member 90 and the cover member 120), and the cap member 140 is main-engaged with the base member 90.

[0108] Also, a pair of slits 109, 109 parallel to each other are formed at the axially proximal end of the cylindrical wall portion 91, and flexible pieces 110 that can be elastically deformed are formed through the pair of slits 109, 109. In this embodiment, four flexible pieces 110 are formed at equal intervals in the circumferential direction of the cylindrical wall portion 91.

[0109] Engagement portions 111 that engage with the back peripheral edge of the case opening 3 project from the outer periphery of the distal ends of the flexible pieces 110 in the extending direction. The engagement portions 111 have tapered outer surfaces of the base and the tip with the top as a boundary. Also, a raised portion 112 that bulges inward in the radial direction of the cylindrical wall portion 91 is provided on the inner periphery of the distal ends of the flexible pieces 110.

[0110] And when the cap member 140 is temporarily held by the base member 90 and the pushing member 130 is not pushed by the cap member 140, the peripheral wall 131 of the pushing member 130 is not located inside the raised portion 112 (see FIG. 21), and the raised portion 112 and the peripheral wall 131 are radially separated from each other. Therefore, each bending piece 110 can be bent and deformed toward the radially inner side of the cylindrical wall portion 91, so that the cylindrical wall portion 91 can be inserted from the front side to the back side of the case opening 3 (see FIG. 21).

[0111] On the other hand, as shown in FIG. 22, when the cap member 140 is properly engaged with the base member 90, the pushing member 130 is pushed by the cap member 140. As a result, the peripheral wall 131 of the pushing member 130 is located inside the raised portion 112, and the raised portion 112 approaches the peripheral wall 131. Then, each bending piece 110 cannot be bent and deformed toward the radially inner side of the cylindrical wall portion 91, so that the situation where the cylindrical wall portion 91 is pulled out from the case opening 3 is prevented, and the base member 90 is retained at the case opening 3 so as not to come off.

[0112] In addition, a plurality of receiving portions 113 are provided on the inner peripheral surface of the cylindrical wall portion 91 on the base end portion side with respect to the bottom plate portion 93, forming ridges extending along the circumferential direction by a predetermined length from a predetermined height position. In a state where the cap member 140 is temporarily held by the base member 90, the receiving portion 113 receives the base end portion of the peripheral wall 131 of the pushing member 130 (see FIG. 19) and holds the peripheral wall 131 of the pushing member 130 so as not to be located inside the raised portion 112 of the bending piece 110.

[0113] Furthermore, a plurality of engaging protrusions 114 project from a position closer to the base end (the tip in the extending direction) of the cylindrical wall portion 91 than the receiving portion 113 on the inner peripheral surface of the cylindrical wall portion 91 on the base end portion side with respect to the bottom plate portion 93.

[0114] Then, the cap member 140 is properly engaged with the base member 90, the pushing member 130 is pushed through the second seal member 80A, and when the peripheral wall 131 of the pushing member 130 is positioned inside the raised portion 112 of the flexing piece 110 (see Fig. 22), a predetermined engaging claw 134 (see Fig. 16) provided on the pushing member 130 can be engaged with each engaging protrusion 114, holding the pushing member 130 in that position.

[0115] Also, a plurality of positioning grooves 115 formed in a concave groove shape extending along the axial direction are formed at predetermined positions on the inner peripheral surface of the cylindrical wall portion 91 on the base end side of the bottom plate portion 93. A predetermined protrusion 135 (see Fig. 17) provided on the pushing member 130 is inserted into each positioning groove 115, serving as a pushing guide when pushing the pushing member 130 into the base member 90, restricting the rotation of the pushing member 130 with respect to the base member 90, and restricting the pushing of the pushing member 130 with respect to the base member 90 by the protrusion 135 abutting against the lower end surface thereof (see Fig. 24).

[0116] Next, referring to Fig. 12, Fig. 18, etc., the first seal member 20A attached to the base end side of the base member 90 will be described.

[0117] The first seal member 20A of this embodiment has a main body portion 21 having a substantially circular plate shape. From the outer periphery of this main body portion 21, seal flange portions 22, 24 in an annular thin-walled flange shape extend obliquely outward so as to be spaced apart from each other. One seal flange portion 22 elastically abuts against the front peripheral edge of the case opening 3 (see Fig. 22), and the other seal flange portion 24 elastically abuts against the back surface of the bottom plate portion 93 of the base member 90 (see Fig. 18).

[0118] Also, a plurality of annular seal protrusions 29 project from the back surface and the front surface of the main body portion 21.

[0119] Then, as shown in FIG. 18, by disposing the first seal member 20A on the outer periphery of the tip of the cylindrical wall portion 91 of the base member 90, the inner peripheral edge portion of the main body portion 21 abuts on the outer periphery of the tip of the cylindrical wall portion 91, and a pair of seal protrusions 29, 29 on the surface side of the main body portion 21 abut on the back surface of the bottom plate portion 93 of the base member 90, and the first seal member 20A is attached to the base member 90.

[0120] Further, the cylindrical wall portion 91 of the base member 90 is inserted from the front side of the case opening 3, and each engaging portion 111 on the outer periphery of the flexible piece engages with the peripheral edge portion on the back side of the case opening 3. As shown in FIG. 22, in a state where the release valve 10A is attached to the case opening 3, the seal flange portion 22 of the first seal member 20A abuts on the peripheral edge portion on the front side of the case opening 3, and a pair of seal protrusions 29, 29 on the back surface side of the main body portion 21 abut.

[0121] That is, the back surface of the seal flange portion 22 and the back surfaces of a pair of seal protrusions 29, 29 projecting from the back surface side of the main body portion 21 form a first seal surface 28A that abuts on the peripheral edge portion of the case opening 3.

[0122] Next, with reference to FIGS. 15 and 20, etc., the cover member 120 attached to the tip end side of the base member 90 will be described.

[0123] The cover member 120 of this embodiment has a peripheral wall 121 having a substantially cylindrical shape and a ceiling wall 123 protruding in an annular flange shape from the inner periphery of the tip of the peripheral wall 121. The peripheral wall 121 is disposed outside the surface opening of the opening 97 of the base member 90, and the ceiling wall 123 is disposed on the front side of the ceiling plate portion 94 of the base member 90.

[0124] Further, on the outer peripheral edge portion side of the ceiling wall 123, a plurality of positioning holes 123a are formed at equal intervals in the circumferential direction. The positioning protrusions 104 (see FIG. 14) provided on the base member 90 are inserted into the respective positioning holes 123a to restrict the rotation of the cover member 120 with respect to the base member 90.

[0125] Further, on the inner circumference of the peripheral wall 121, a plurality of guide ribs 121a are provided at equal intervals in the circumferential direction and extend along the axial direction of the peripheral wall 121. Each guide rib 121a is inserted into a guide groove 105 provided in the base member 90 to guide the cover member 120 when assembling the cover member 120 to the base member 90 and to restrict the rotation of the cover member 120 with respect to the base member 90.

[0126] Also, at the base end portion of the peripheral wall 121, a plurality of substantially L-shaped slits 124 each formed of a circumferentially extending groove and an axially extending groove are formed. Through each slit 124, a plurality of plate-like pieces 125 having a long plate shape and being capable of being elastically deformed are provided. As shown in FIG. 26, each plate-like piece 125 can open and close an opening portion 127 having a substantially long hole shape through a fixed end portion 126 having a thin-wall hinge shape.

[0127] Further, a plurality of locking claws 128 project from the inner circumference of the base end portion of the peripheral wall 121. As shown in FIG. 21, these locking claws 128 are adapted to lock to the base end faces of the first plate-like piece 98 and the third plate-like piece 100 of the base member 90.

[0128] Note that, in a state where the cover member 120 is attached to the base member 90, a gap 129 is formed between the base end portion of the peripheral wall 121 of the cover member 120 and the bottom plate portion 93 of the base member 90 (see FIGS. 22 and 23), and the gap 129 communicates with the opening 97.

[0129] Next, with reference to FIGS. 16, 18, etc., a pushing member 130 that can be pushed into the base member 90 and restricts the inward flexural deformation of the flexure piece 110 in the base member will be described.

[0130] The pushing member 130 of this embodiment has a peripheral wall 131 having a substantially cylindrical shape. And an inner circumferential opening of this peripheral wall 131 forms a vent hole 132 that communicates the internal space R1 of the case and the external space R2 of the case.

[0131] Further, a pair of slits 133a, 133a are formed in parallel with each other from the axially proximal edge of the peripheral wall 131 toward the axially distal end side, and a deformable bending piece 133 is formed through the pair of slits 133a, 133a. A plurality of the bending pieces 133 are formed at predetermined intervals in the circumferential direction of the peripheral wall 131.

[0132] Further, engaging claws 134 project from the outer periphery of the distal end portion in the extending direction of each bending piece 133. When the pushing member 130 is pushed through the second seal member 80A and the peripheral wall 131 of the pushing member 130 is positioned inside the raised portion 112 of the bending piece 110, each engaging claw 134 can engage with an engaging projection 114 provided on the base member 90 to hold the pushing member 130 in the above position.

[0133] Furthermore, a plurality of ridges 135 are axially extended on the outer periphery of the peripheral wall 131 at equal intervals in the circumferential direction. Each ridge 135 is inserted into a predetermined positioning groove 115 provided in the base member 90 to serve as a pushing guide of the pushing member 130 with respect to the base member 90, restrict the rotation of the pushing member 130 with respect to the base member 90, and abut against the lower end surface of the positioning groove 115 to restrict the pushing of the pushing member 130 with respect to the grommet 90A (see FIG. 24).

[0134] In addition, a mounting projection 136 for mounting the second seal member 80A is provided at the distal end portion of the peripheral wall 131. Further, a substantially cross-shaped cap receiving portion 137 is installed on the inner periphery of the proximal end portion of the peripheral wall 131. As shown in FIG. 16, a valve body receiving portion 138 for receiving the bottom portion of the valve body 60A is formed on the upper surface side of the cap receiving portion 137.

[0135] Next, with reference to FIGS. 12, 18, etc., the second seal member 80A attached to the pushing member 130 will be described.

[0136] The second seal member 80A of this embodiment has a cylindrical portion 81 having a substantially cylindrical shape, and a mounting groove 85 is formed on the inner peripheral side thereof. As shown in FIG. 18, by inserting the mounting projection 136 of the pushing member 130 into the mounting groove 85, the second seal member 80A is mounted on the outer periphery of the tip end portion of the pushing member 130.

[0137] Further, a valve seat 86 having an annular projection shape projects from the inner peripheral edge portion on the axial front end side of the cylindrical portion 81. The second seal surface 65 provided on the valve body 60A contacts and separates from the valve seat 86 to open and close the vent hole 132 (see FIGS. 22 and 25).

[0138] Furthermore, a seal projection 87 having an annular projection shape projects from the outer periphery of the base end portion of the cylindrical portion 81. As shown in FIGS. 22 and 23, this seal projection 87 elastically abuts against the inner peripheral surface of the cylindrical wall portion 91 of the base member 90 to seal the gap between the cylindrical wall portion 91 and the second seal member 80A.

[0139] Next, referring to FIGS. 17, 19, etc., a cap member 140 that supports one end 5a of the biasing spring 5 and pushes the pushing member 130 through the second seal member 80A will be described.

[0140] The cap member 140 of this embodiment has a ceiling plate 141 having a substantially circular plate shape, a peripheral wall 142 vertically provided with a predetermined length from the outer peripheral edge portion of the ceiling plate 141, and a cylindrical portion 143 having a substantially cylindrical shape protruding from the central portion of the back surface of the ceiling plate 141.

[0141] As shown in FIG. 20, one end portion of the biasing spring 5 is inserted inside the cylindrical portion 143, and one end 5a of the biasing spring 5 is supported at the central portion of the back surface of the ceiling plate 141. Further, as shown in FIGS. 22 and 25, the cylindrical portion 143 is disposed on the inner periphery of the cylindrical portion 61 of the valve body 60A and guides the sliding operation of the valve body 60A that slides up and down with respect to the cap member 140.

[0142] Furthermore, from the tip end in the extending direction of the peripheral wall 142, a plurality (here, four) of engaging pieces 144 are provided at equal intervals in the circumferential direction. Each engaging piece 144 extends in a direction away from the ceiling plate 141 from the tip end of the peripheral wall, and is folded back in a direction approaching the ceiling plate 141 via a curved bending portion 144a, forming a substantially U shape as a whole.

[0143] Also, engaging claws 145 project from the outer periphery of the tip end of each engaging piece 144. Then, as shown in FIG. 20, when the engaging claws 145 engage with the temporary engaging surface 103 of the base member 90, the cap member 140 is temporarily held by the base member 90. On the other hand, as shown in FIG. 22, when the engaging claws 145 engage with the main engaging surface 107 of the main engaging projection 106 of the base member 90, the cap member 140 is main-engaged with the base member 90.

[0144] Furthermore, as shown in FIG. 19, from a position on the back surface of the ceiling plate 141 that is slightly offset radially inward from the outer peripheral edge of the ceiling plate 141, a plurality of long plate-shaped pressing plates 146 are vertically provided.

[0145] Each pressing plate 146 presses the outer peripheral edge portion on the axial tip end side of the cylindrical portion 81 of the second seal member 80A, and indirectly presses the pushing member 130 via the second seal member 80A when pushing the cap member 140 against the base member 90.

[0146] Also, plate-shaped ribs 147 and 148 project orthogonally to the pressing plate 146 from the outer surface at the center in the width direction of each pressing plate 146.

[0147] The rib 147 is provided between a predetermined engaging piece 144 and the pressing plate 146 at a position corresponding to the engaging piece 144, and a receiving portion 147a for receiving the protruding portion 91a of the cylindrical wall portion 91 of the base member 90 is formed on the tip end side thereof (see FIGS. 19 and 22).

[0148] Also, as shown in FIG. 17, a receiving portion 148a for receiving the protruding portion 91a of the cylindrical wall portion 91 of the base member 90 is also formed at the tip of the rib 148, which is located between the engaging pieces 144, 144 adjacent in the circumferential direction.

[0149] Next, the valve body 60A will be described with reference to FIGS. 12, 19, etc.

[0150] The valve body 60A of this embodiment has a cylindrical portion 61 having a substantially cylindrical shape, a flange portion 62 having a substantially circular plate shape that projects from the outer periphery near the tip of the cylindrical portion 61, and a spring support portion 63 having a substantially hat shape that is provided on the inner periphery of the base end portion of the cylindrical portion 61. Note that, unlike the valve body 60 of the above embodiment, the valve body 60A has a structure in which the second seal member is not attached.

[0151] The cylindrical portion 61 is disposed on the outer periphery of the cylindrical portion 143 of the pushing member 130, and the lifting and sliding operation of the valve body 60A is guided (see FIGS. 22 and 25). Further, the spring support portion 63 is inserted into the inner periphery of the other end portion of the biasing spring 5 and abuts against the other end 5b of the biasing spring 5 to support the other end portion of the biasing spring 5 (see FIG. 22).

[0152] Furthermore, an annular protrusion projects from the back surface of the outer peripheral edge portion of the flange portion 62, and the back surface of the annular protrusion forms a second seal surface 65 that abuts against the peripheral edge portion of the vent hole 44 (separates from and contacts the valve seat 86).

[0153] And as shown in FIG. 22, the second seal surface 65 is provided so as to be located on the side of the external space R2 of the case 1 rather than the first seal surface 28A, which is composed of the back surface of the flange portion 22 and the back surfaces of the pair of seal protrusions 29, 29.

[0154] Also, as shown in FIG. 25, in a state where the second seal surface 65 is maximally separated from the valve seat 86, the second seal surface 65 is configured to be located on the side of the external space R2 of the case rather than the inner edge portion 97a closest to the case internal space R1 side of the opening 97 provided in the housing 15A (here, the base member 90 constituting the housing 15A).

[0155] Note that the inner edge of the opening means the portion that communicates with the opening in the member constituting the housing and is closest to the case internal space R1 side in the radial inner direction and the axial direction of the housing. As shown in FIG. 23, in the case of this embodiment, the tip of the protruding portion 91a of the cylindrical wall portion 91 in the base member 90 that constitutes the housing 15A and has the opening 97 forms the inner edge portion 97a of the opening 97.

[0156] (Function and Effect) Next, the function and effect of the relief valve 10A having the above configuration will be described.

[0157] First, the assembly process of the relief valve 10A will be described.

[0158] First, by inserting the mounting protrusion 136 of the pushing member 130 into the mounting groove 85 of the second seal member 80A, the second seal member 80A is mounted on the outer periphery of the tip of the pushing member 130 to assemble the first assembly 16A (see FIG. 18). Also, by disposing the first seal member 20A on the outer periphery of the tip of the cylindrical wall portion 91 of the base member 90, the first seal member 20A is mounted on the base member 90 to assemble the second assembly 17A (see FIG. 18).

[0159] Next, the first assembly 16A and the second assembly 17A are assembled. That is, the corresponding ridges 135 of the pushing member 130 are aligned with the respective positioning grooves 115 of the base member 90, and the pushing member 130 is pushed into the base member 90. Then, the pushing member 130 is pushed while being guided by the ridges 135 inserted into the positioning grooves 115.

[0160] Thereafter, the base end portion of the peripheral wall 131 of the pushing member 130 is received by the receiving portion 113 of the base member 90, further pushing of the pushing member 130 is restricted, and the pushing member 130 is rotationally restricted with respect to the base member 90, and the third assembly 18A is assembled (see FIG. 19).

[0161] In addition, in the state where the third assembled body 18A is assembled, the base end portion of the peripheral wall 131 of the pushing member 130 is drawn into the distal end side of the cylindrical wall portion 91 of the base member 90 rather than the base end portion of the cylindrical wall portion 91, and the peripheral wall 131 of the pushing member 130 is not positioned inside the raised portion 112 of the bending piece 110. Therefore, each bending piece 110 can be bent and deformed inward of the cylindrical wall portion 91.

[0162] Next, the valve body 60A is inserted through the upper opening of the base member 90, and the outer peripheral edge portion of the flange portion 62 of the valve body 60A is brought into contact with the valve seat 86 of the second seal member 80A to support the valve body 60A. Then, the other end portion of the biasing spring 5 is supported by the spring support portion 63 of the valve body 60A.

[0163] Also, the corresponding engaging pieces 144 of the cap member 140 are aligned with the respective notches 102 of the base member 90, and the cap member 140 is pushed into the base member 90. Then, one end portion of the biasing spring 5 is inserted and supported in the cylindrical portion 143 of the cap member 140, and the engaging claws 145 of the respective engaging pieces 144 are engaged with the temporary engaging surface 103 of the base member 90, and the base end portion of the peripheral wall 131 is engaged with (received by) the receiving portion 113, and the cap member 140 is temporarily held by the base member 90 (see FIG. 20).

[0164] Thereafter, the corresponding positioning holes 123a of the cover member 120 are aligned with the respective positioning protrusions 104 of the base member 90, and the cover member 120 is pushed into the base member 90. Then, the cover member 120 is guided and pushed into the base member 90 by the guide ribs 121a inserted into the guide grooves 105.

[0165] Then, the respective locking claws 128 of the cover member 120 are locked to the base end surfaces of the first plate-like piece 98 and the third plate-like piece 100 of the base member 90, and the respective positioning protrusions 104 of the base member 90 are inserted into the corresponding positioning holes 123a of the cover member 120, so that the cover member 120 is mounted on the base member 90 in a state where its rotation is restricted (see FIG. 21).

[0166] In the above state, the cap member 140 is temporarily held by the base member 90, and the pushing member 130 is not pushed by the cap member 140. Since the peripheral wall 131 of the pushing member 130 is not located inside the raised portion 112, each bending piece 110 can be bent and deformed inward in the radial direction of the cylindrical wall portion 91.

[0167] Then, as shown in the insertion direction F in FIG. 21, the release valve 10A is inserted from the front side of the case opening 3. Then, the tapered outer surface of the engaging portion 111 of the base member 90 is pressed against the inner periphery of the case opening 3, and the bending piece 110 is bent and deformed inward of the cylindrical wall portion 91.

[0168] Thereafter, until the seal flange portion 22 of the first seal member 20A and the pair of seal protrusions 29, 29 abut against the peripheral edge portion on the front side of the case opening 3, the release valve 10 is pushed into the case opening 3. When the top of the engaging portion 111 passes through the back opening of the case opening 3, the bending piece 110 elastically returns, and the tapered outer surface of the tip portion of the engaging portion 111 engages with the peripheral edge portion on the back side of the case opening 3, and the release valve 10A is temporarily fixed to the case opening 3.

[0169] From the above state, the cap member 140 is pushed toward the insertion direction F with respect to the base member 90. Then, the plurality of pressing plates 146 of the cap member 140 press the second seal member 80A, and the pushing member 130 is pushed through the second seal member 80A.

[0170] Thereafter, when the pushing member 130 is pushed until the tip of the protrusion 135 abuts against the lower end surface of the positioning groove 115, the base end portion of the peripheral wall 131 of the pushing member 130 is disposed inside the raised portion 112 of the bending piece 110 of the base member 90, and the engaging claw 134 of the bending piece 133 of the pushing member 130 engages with the engaging protrusion 114 of the base member 90 (see FIG. 23). At the same time, the engaging claw 145 of the cap member 140 engages with the main engaging surface 107 of the main engaging protrusion 106 (see FIG. 22). Further, the tip of the protrusion 135 abuts against and engages with the lower end surface of the positioning groove 115 (see FIG. 24).

[0171] As a result, since the cap member 140 is properly engaged with the base member 90, as shown in Fig. 22, the relief valve 10A can be firmly fixed to the case opening 3.

[0172] In the state shown in Fig. 22, since the peripheral wall 131 of the pushing member 130 is positioned inside the raised portion 112 of the deflecting piece 110 of the base member 90, each deflecting piece 110 cannot deflect inwardly of the cylindrical wall portion 91. As a result, the base member 90 is retained against removal from the case opening 3, and the state in which the relief valve 10A is firmly fixed to the case opening 3 can be maintained.

[0173] Furthermore, as shown in Figs. 19 and 22, the cap member 140 has an engaging piece 144 having a substantially U shape, and a receiving portion 147a for receiving the protruding portion 91a of the cylindrical wall portion 91 of the base member 90 is formed between the base end portion 144b of the engaging piece 144 and the pressing plate 146. Also, as shown in Fig. 22, in the state where the relief valve 10A is firmly fixed to the case opening 3 and the protruding portion 91a is received in the receiving portion 147a, the base end portion 144b of the engaging piece 144 is arranged at a position slightly separated from the outer periphery of the protruding portion 91a of the cylindrical wall portion 91.

[0174] Therefore, when temporarily holding the cap member 140 on the base member 90, the protruding portion 91a can be easily received in the receiving portion 147a. Also, when a force acts in a direction in which the cap member 140 is separated from the base member 90 in the state where the relief valve 10A is firmly fixed to the case opening 3, the engaging piece 144 deflects inwardly of the cover member, and its base end portion 144b abuts against the protruding portion 91a, so that the protruding portion 91a is less likely to come out of the receiving portion 147a.

[0175] That is, it becomes easy to temporarily hold the cap member 140 on the base member 90, and after firmly fixing the relief valve 10A to the case opening 3, it is possible to make it difficult for the cap member 140 to come off from the base member 90.

[0176] Also, as shown in Fig. 21, when the cap member 140 is temporarily held by the base member 90, the seal protrusion 87 provided on the second seal member 80A abuts against the inner circumference of the cylindrical wall portion 91 of the base member 90, so that the sealing performance in the temporarily held state can be improved.

[0177] Also, in the state shown in Fig. 22, the biasing spring 5 held in a compressed state between the cap member 140 and the valve body 60A biases the second seal surface 65 of the valve body 60A toward the valve seat 86 provided on the second seal member 80A, and the second seal surface 65 abuts against the valve seat 86, closing the vent hole 132.

[0178] When the pressure in the internal space R1 of the case 1 rises and exceeds the biasing force of the biasing spring 5, the valve body 60A slides in a direction away from the valve seat 86 against the biasing force, and the second seal surface 65 separates from the valve seat 86.

[0179] Then, as shown in Fig. 25, the vent hole 132 provided in the pushing member 130 opens, and through this vent hole 132, the internal space R1 of the case communicates with the external space R2 of the case. In this embodiment, the internal space R1 of the case communicates with the internal space R3 of the housing via the vent hole 132, and the internal space R3 of the housing communicates with the external space R2 of the case via the opening 97, the gap 129, etc.

[0180] Therefore, gas such as the gas in the internal space R1 of the case flows into the internal space R3 of the housing from the vent hole 132, passes through the gap between the engaging pieces 144, 144 of the cap member 140, etc., and after passing through the opening 97 beyond the inner edge portion 97a (the tip portion in the protruding direction of the protruding portion 91a of the cylindrical wall portion 91) of the opening 97 of the base member 90, it is exhausted from the gap 129 to the external space R2 of the case (see the arrow in Fig. 25). As a result, the pressure in the case can be released.

[0181] And in this relief valve 10A, as shown in Fig. 22, the second seal surface 65 is provided so as to be located on the side of the external space R2 of the case 1 rather than the first seal surface 28A.

[0182] Therefore, when the pressure in the internal space R1 of the case rises and the valve body 60A slides in a direction away from the valve seat 86 against the biasing force of the biasing spring 5, and the second sealing surface 65 moves away from the valve seat 86 and the vent hole 132 opens, the passage R4 (see FIG. 25) formed between the valve seat 86 and the second sealing surface 65 can be made closer to the opening 97. Here, the passage R4 can be axially lapped (overlapped) with respect to the opening 97.

[0183] As a result, the gas generated in the internal space R1 of the case can be easily discharged to the external space R2 of the case through the internal space R3 of the housing.

[0184] Also, in this embodiment, the housing 15A is disposed on the side of the external space R2 of the case and has an opening 97 that radially communicates the internal space and the external space of the housing 15A. Further, as shown in FIG. 23, in a state where the second sealing surface 65 is maximally separated from the valve seat 86, the second sealing surface 65 is configured to be located on the side of the external space R2 of the case rather than the inner edge portion 97a closest to the internal space R1 of the case of the opening 97.

[0185] According to the above aspect, when the pressure in the internal space R1 of the case rises and the valve body 60A slides in a direction away from the valve seat 86 against the biasing force of the biasing spring 5, and the second sealing surface 65 is maximally separated from the valve seat 86, the passage R4 formed between the valve seat 86 and the second sealing surface 65 and the opening 97 provided in the housing 15A can be directly communicated.

[0186] As a result, the gas generated in the internal space R1 of the case can be easily discharged to the external space R2 of the case through the internal space R3 of the housing.

[0187] Furthermore, in this embodiment, the housing 15A has a base member 90 fixed to the case opening 3 and a cover member 120 attached to the base member 90. The cover member 120 has a peripheral wall 121 and a plate-like piece 125 formed on the peripheral wall 121 so as to be elastically deformable via a slit 124.

[0188] For example, when a power storage device such as a battery housed in the case internal space R1 undergoes thermal runaway, a large amount of gas may be generated in the case internal space R1, and the pressure in the case internal space R1 may rise rapidly.

[0189] In such a case, the valve body 60A slides and the vent hole 132 opens, and the gas flows from the vent hole 132 into the housing internal space R3 and is discharged to the case external space R2. At this time, the inner surface of the plate-like piece 125 is pressed by the gas, and as shown in FIG. 24, the plate-like piece 125 is elastically deformed outward of the peripheral wall.

[0190] As a result, the gas can be discharged from the opening portion 127 of the peripheral wall 121 after the deformation of the plate-like piece, so that the gas can be easily discharged to the case external space R2.

[0191] (Another embodiment of the pressure relief valve for a power storage device) FIG. 27 shows still another embodiment of the pressure relief valve for a power storage device according to the present invention. Note that the same reference numerals are given to substantially the same parts as those in the above embodiment, and the description thereof is omitted.

[0192] As shown in FIG. 27, the pressure relief valve 10B for a power storage device in this embodiment (hereinafter, also simply referred to as "relief valve 10B") is different from the embodiments shown in FIGS. 12 to 26 in the shape of the cover member 120B.

[0193] That is, in the cover member 120B in this embodiment, an opening 122 is formed between the tip of the peripheral wall 121 and the ceiling wall 123, and a plurality of the openings 122 are formed in the circumferential direction of the peripheral wall 121 and the ceiling wall 123. Further, each opening 122 communicates with the internal space of the cover member 120B.

[0194] And also in this embodiment, for example, when a large amount of gas is generated in the case internal space R1 and the pressure in the case internal space R1 rapidly rises, the gas can be quickly discharged from the plurality of openings 122.

[0195] Note that the present invention is not limited to the above-described embodiments, and various modified embodiments are possible within the scope of the gist of the present invention, and such embodiments are also included in the scope of the present invention.

Explanation of Reference Numerals

[0196] 1 Case 3 Case opening 5 Biasing spring 5a One end 5b The other end 10, 10A Pressure relief valve for power storage device (relief valve) 15, 15A Housing 20, 20A First seal member 28, 28A First seal surface 30, 120 Cover member 40, 90 Base member 41 Peripheral wall 44 Vent hole 45 Valve seat 50, 140 Cap member 53 Cylindrical portion 53a Opening 54 Spring support portion 60 Valve body 70 Valve body 72 Shaft portion 73 Spring support portion 80 Second seal member 81 Cylindrical portion 82a Second seal surface 97 Opening 130 Pushing member R1 Case internal space R2 Case external space

Claims

1. A pressure relief valve for a power storage device, which is attached to a case in which the power storage device is housed, a housing that is inserted into and fixed to a case opening formed in the case, has a vent hole that communicates the internal space and the external space of the case, and a valve seat provided at its peripheral edge; a valve body that is slidable with respect to the housing and opens and closes the vent hole; and a biasing spring that biases the valve body toward the valve seat, wherein the housing has a first sealing surface that abuts against a peripheral edge portion of the case opening, the valve body has a second sealing surface that abuts against a peripheral edge portion of the vent hole, the biasing spring is disposed between the housing and the valve body, one end thereof is supported by the housing, and the other end presses the valve body, the housing is fixed to the case opening, and when viewed from a direction orthogonal to the axial direction of the valve body in a state where the vent hole is closed by the valve body, the first sealing surface and the second sealing surface are configured to be disposed between one end and the other end of the biasing spring. A pressure relief valve for a power storage device, characterized by this.

2. The valve body has a spring support portion that supports the other end of the biasing spring, and a surface of the spring support portion on the side opposite to the support surface of the biasing spring is configured not to protrude with respect to an end surface of a tip portion of the housing in the insertion direction into the case opening. The pressure relief valve for a power storage device according to Claim 1.

3. The housing has a cylindrical portion, the valve body has a shaft portion that is inserted into and supported by the cylindrical portion, and the shaft portion is configured not to protrude from the surface of the housing when the valve body is fully opened from the vent hole. The pressure relief valve for a power storage device according to Claim 1 or 2.

4. The valve body has a valve main body and a seal member attached to the outer periphery of the valve main body, an annular groove is formed inside the seal member, and the outer periphery of the valve main body is fitted into the annular groove so that the seal member is attached to the outer periphery of the valve main body, and the second sealing surface is provided on an end surface of the seal member facing the vent hole side. The pressure relief valve for a power storage device according to Claim 1 or 2.

5. The second sealing surface is provided so as to be located on the external space side of the case rather than the first sealing surface. The pressure relief valve for a power storage device according to Claim 1 or 2.

6. The housing is disposed on the external space side of the case and has an opening that radially communicates the internal space and the external space of the housing. The pressure relief valve for a power storage device according to claim 1 or 2, wherein, in a state where the second sealing surface is farthest from the valve seat, the second sealing surface is configured to be located on the external space side of the case rather than the inner edge portion of the opening closest to the internal space side of the case.

7. The housing has a base member fixed to the case opening and a cover member attached to the base member. The cover member has a peripheral wall and a plate-like piece formed on the peripheral wall so as to be elastically deformable via a slit. The pressure relief valve for a power storage device according to claim 1 or 2.

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