Pressure reduction valve

Abstract

In the present invention, a piston (52) has: a first portion (63); a second portion (64) that extends from the first portion (63) toward a valve body (31) and that is narrower than the first portion (63); a third portion (65) that extends from the second portion (64) toward the valve body (31) and that is narrower than the second portion (64); and a fourth portion that extends from the third portion (65) toward the valve body (31) and that is narrower than the third portion (65). The inside of an accommodation hole (13) is partitioned into a pressure adjustment chamber (74) and a pressure reduction chamber (75) as a result of a seal member (73) being disposed on the outer periphery of the second portion (64). A section of the second portion (64), the third portion (65), and the fourth portion is disposed in the pressure adjustment chamber (74), and the first portion (63) and a remaining section of the second portion (64) are disposed in the pressure reduction chamber (75).

Description

Pressure reducing valve

[0001] The present disclosure relates to a pressure reducing valve.

[0002] Conventionally, as described in, for example, Patent Document 1, there is a pressure reducing valve that reduces the pressure of gas supplied from a gas tank to a predetermined pressure and delivers it to a consumer device. The pressure reducing valve includes a gas flow path including a primary flow path connected to the gas tank and a secondary flow path connected to the consumer device, and a body having a housing bore connected to each of the primary flow path and the secondary flow path. The pressure reducing valve also includes a valve seat provided in the primary flow path, a valve element slidably received in the primary flow path, a cover fixed to the housing bore, a piston slidably received in the housing bore, and a biasing member disposed between the cover and the piston. The biasing member biases the valve element in a direction to move it away from the valve seat via the piston. The interior of the housing bore is partitioned by a seal member provided on the outer periphery of the piston into a pressure adjustment chamber between the bottom of the housing bore and the piston and a pressure reduction chamber between the piston and the cover. The primary flow path and the secondary flow path are open to the pressure adjustment chamber, through which reduced-pressure gas flows. The pressure reduction chamber is open to, for example, the atmosphere.

[0003] In this type of pressure reducing valve, the piston slides within the bore in response to the pressure difference between the pressure adjustment chamber and the pressure reduction chamber, and the biasing force of the biasing member. As the piston slides, the valve disc approaches or moves away from the valve seat, changing the gap between the valve disc and the valve seat. Gas flowing through the primary flow path is decompressed according to the size of the gap, enters the pressure adjustment chamber, and is discharged from the secondary flow path. When the pressure in the pressure adjustment chamber reaches a predetermined pressure, the valve disc seats on the valve seat. This restricts excessive gas from flowing into the pressure adjustment chamber, preventing the pressure of the gas discharged from the secondary flow path from exceeding the predetermined pressure.

[0004] Japanese Patent Application Laid-Open No. 2019-199926

[0005] In the pressure reducing valve described above, when the predetermined pressure, i.e., the maximum value of the secondary pressure which is the pressure inside the pressure adjusting chamber, is set high, it is necessary to increase the biasing force of the biasing member according to the desired pressure. Therefore, when the predetermined pressure is set high, the biasing member becomes larger. As a result, many peripheral parts, such as the piston and cover which receive the biasing force of the biasing member, and the body which houses these parts, also become larger.

[0006] A pressure reducing valve according to one aspect of the present disclosure includes a body having a gas flow path including a primary flow path and a secondary flow path and a housing bore connected to each of the primary flow path and the secondary flow path, a valve seat provided in the primary flow path, a valve element slidably received in the primary flow path, a cover fixed to the housing bore, a piston slidably received in the housing bore and abutting the valve element, a biasing member disposed between the piston and the cover and configured to bias the valve element in a direction away from the valve seat via the piston, and a seal member provided on an outer periphery of the piston. The piston has a first portion configured to receive the biasing force of the biasing member, a second portion extending from the first portion toward the valve element and narrower than the first portion, a third portion extending from the second portion toward the valve element and narrower than the second portion, and a fourth portion extending from the third portion toward the valve element and narrower than the third portion, the fourth portion abutting the valve element. The seal member is disposed on the outer periphery of the second portion, thereby dividing the interior of the accommodating hole into a pressure adjustment chamber between the bottom of the accommodating hole and the piston, and a decompression chamber between the piston and the cover. The primary-side flow path and the secondary-side flow path open into the pressure adjustment chamber, and a part of the second portion, the third portion, and the fourth portion are disposed in the pressure adjustment chamber, while the first portion and the remaining portion of the second portion are disposed in the decompression chamber.

[0007] Fig. 2 is a partial cross-sectional view of a pressure reducing valve of a first embodiment; Fig. 3 is an enlarged cross-sectional view of the periphery of a piston in the pressure reducing valve of Fig. 1; Fig. 4 is an enlarged cross-sectional view of the periphery of a piston in a pressure reducing valve of a second embodiment;

[0008] First Embodiment A first embodiment of a pressure reducing valve will be described below with reference to the drawings. A pressure reducing valve (sometimes referred to as a regulator) 1 shown in FIG. 1 is provided in a fluid circuit connecting a hydrogen gas supply source 2 to a hydrogen consumption device 3. The supply source 2 is, for example, a gas tank filled with hydrogen gas. The pressure reducing valve 1 includes a body 4, a valve mechanism 5 provided within the body 4, and a pressing mechanism 6 that adjusts the opening amount (opening degree) of the valve mechanism 5. The hydrogen consumption device 3 may be, for example, a hydrogen engine mounted on a hydrogen engine vehicle or a fuel cell mounted on a fuel cell vehicle. The pressure reducing valve 1 reduces the pressure of hydrogen gas supplied from the supply source 2 to a predetermined pressure or lower and supplies the reduced pressure gas to the hydrogen consumption device 3. The primary pressure, which is the pressure of the hydrogen gas supplied to the pressure reducing valve 1, is a high pressure, for example, approximately 87.5 MPa. The predetermined pressure is a target value for the pressure reduced by the pressure reducing valve 1.

[0009] (Body) The body 4 is made of metal. The body 4 has a gas flow path including a primary side flow path 11 connected to the supply source 2 and a secondary side flow path 12 connected to the consuming device 3, and a housing hole 13 connected to each of the primary side flow path 11 and the secondary side flow path 12. The primary side flow path 11 opens to the outside of the body 4 and to the inside of the housing hole 13. The opening of the primary side flow path 11 to the outside is used as a primary port. A pipe (not shown) extending from the supply source 2 is connected to the primary port. The secondary side flow path 12 opens to the outside of the body 4 and to the inside of the housing hole 13. The opening of the secondary side flow path 12 to the outside is used as a secondary port. A pipe (not shown) extending from the consuming device 3 is connected to the secondary port. Hydrogen gas flows from the primary side flow path 11 via the housing hole 13 to the secondary side flow path 12.

[0010] The primary flow passage 11 extends, for example, linearly and has a circular cross section. An expansion section 15 having an inner diameter larger than that of an upstream portion of the primary flow passage 11 is provided at an opening of the primary flow passage 11 leading to the interior of the accommodation hole 13. The secondary flow passage 12 extends, for example, linearly and has a circular cross section.

[0011] The accommodation hole 13 opens toward the outside of the body 4. The accommodation hole 13 has a stepped structure. The cross-sectional shape of the accommodation hole 13 is, for example, circular. Specifically, the accommodation hole 13 has a large hole portion 21, a medium hole portion 22, and a small hole portion 23. The large hole portion 21, the medium hole portion 22, and the small hole portion 23 are arranged in this order from the surface of the body 4 toward the back. The inner diameter of the accommodation hole 13 decreases in the order of the large hole portion 21, the medium hole portion 22, and the small hole portion 23.

[0012] The primary flow passage 11 opens to the bottom surface of the small hole portion 23, and the secondary flow passage 12 opens to the inner circumferential surface of the middle hole portion 22. Specifically, the primary flow passage 11 opens to the center of the bottom surface of the small hole portion 23. The secondary flow passage 12 opens to the inner circumferential surface of the middle hole portion 22, closer to the small hole portion 23, and is radially opposed to a third portion 65 of the piston 52, which will be described later. In the illustrated example, the large hole portion 21, the middle hole portion 22, and the small hole portion 23 are arranged coaxially with the primary flow passage 11.

[0013] (Valve Mechanism) As shown in FIGS. 1 and 2, the valve mechanism 5 includes a valve body (sometimes called a poppet) 31, a valve seat 32, a plug 33, and a first biasing member .

[0014] The valve element 31 is slidably accommodated within the primary flow path 11. The valve element 31 is cylindrical with one end closed. Specifically, the valve element 31 has a cylindrical portion 41, a head portion 42 extending from one end of the cylindrical portion 41, and an abutment portion 43 provided at the tip of the head portion 42. The cylindrical portion 41 has, for example, a rectangular shape when viewed in the axial direction. The head portion 42 has, for example, a tapered shape with an outer diameter decreasing toward the tip. The head portion 42 closes one end of the cylindrical portion 41. The abutment portion 43 has, for example, a cylindrical shape.

[0015] The valve seat 32 has, for example, an annular shape. The valve seat 32 has a valve port 45 that penetrates the valve seat 32 in the axial direction. The valve seat 32 is fixed in the expansion section 15 of the primary-side flow path 11 by, for example, press-fitting. The inner diameter of the valve port 45 is larger than the outer diameter of the abutment section 43 of the valve element 31 and smaller than the maximum outer diameter of the head section 42. The valve seat 32 is made of an elastically deformable hard resin such as polyimide or polyether ether ketone (PEEK).

[0016] The plug 33 is made of metal. The plug 33 has, for example, a cylindrical shape. The plug 33 is fixed to the small hole portion 23 with the valve seat 32 pressed against the bottom surface of the expansion portion 15. As a result, the valve seat 32 airtightly seals between the bottom of the accommodating hole 13 and the plug 33. The plug 33 is fixed to the small hole portion 23 by screw fastening. The plug 33 has a plug hole 46 that passes through the plug 33 in the axial direction. When the plug 33 is fixed to the small hole portion 23, one end of the plug 33 protrudes into the accommodating hole 13. One end of the plug 33 is provided with a communication hole 47 that extends radially of the plug 33 and communicates the interior of the plug hole 46 with the interior of the accommodating hole 13.

[0017] The first biasing member 34 is housed in the cylindrical portion 41 of the valve body 31. The first biasing member 34 is, for example, a coil spring. The first biasing member 34 is compressed between the valve body 31 and a support member 48 arranged in the upstream portion of the primary flow path 11. As a result, the first biasing member 34 biases the valve body 31 toward the valve seat 32.

[0018] (Pressing Mechanism) As shown in FIG. 1 , the pressing mechanism 6 includes a cover 51 , a piston 52 , and a second biasing member 53 .

[0019] The cover 51 is made of metal. The cover 51 has, for example, a cylindrical shape with one end closed. The cover 51 is fixed to the opening of the accommodation hole 13 so that the closed end of the cover 51 faces the outside of the accommodation hole 13. The cover 51 is fixed to the large hole portion 21 by screw fastening. As shown in the example, a lock nut 54 may be fastened to the outer periphery of the closed end of the cover 51.

[0020] 1 and 2, the piston 52 of this embodiment includes a piston body 61 and a pin 62. The piston body 61 and the pin 62 are made of metal. The piston body 61 is a continuous, one-piece component. The pin 62 is a separate component from the piston body 61.

[0021] The piston body 61 has a stepped structure. The cross-sectional shape of the piston body 61 is, for example, circular. Specifically, the piston body 61 has a first portion 63, a second portion 64 that protrudes from the first portion 63 in the axial direction of the piston body 61, and a third portion 65 that protrudes from the second portion 64 in the axial direction of the piston body 61. The outer diameters of the piston body 61 decrease in the order of the first portion 63, the second portion 64, and the third portion 65. The first portion 63 of the piston body 61 is accommodated in the large hole portion 21 of the accommodation bore 13, and the second portion 64 and the third portion 65 are accommodated in the medium hole portion 22. That is, the second portion 64 extends from the first portion 63 toward the valve body 31, and the third portion 65 extends from the second portion 64 toward the valve body 31.

[0022] The outer diameter of the first portion 63 is slightly smaller than the inner diameter of the large hole portion 21. This allows the first portion 63 to slide within the large hole portion 21. A first mounting groove 66 extending in the circumferential direction of the first portion 63 is provided on the outer peripheral surface of the first portion 63.

[0023] The outer diameter of the second portion 64 is slightly smaller than the inner diameter of the bore 22. This allows the second portion 64 to slide within the bore 22. The second portion 64 is thinner than the first portion 63. In this specification, when one portion of the piston 52 is thinner than another portion, it means that the area enclosed by the outer peripheral surface of one portion is smaller than the area enclosed by the outer peripheral surface of the other portion. A second mounting groove 67 and a seal groove 68 are provided on the outer peripheral surface of the second portion 64. The second mounting groove 67 is provided at a position closer to the third portion 65 than the seal groove 68.

[0024] The outer diameter of the third portion 65 is smaller than the inner diameter of the center hole 22. That is, the third portion 65 is thinner than the second portion 64. The outer diameter of the third portion 65 is also larger than the inner diameter of the plug hole 46. Therefore, the third portion 65 is not inserted into the plug hole 46, and the entire third portion 65 is housed within the center hole 22.

[0025] The piston body 61 of this embodiment is manufactured by cutting a continuous, unbroken cylindrical material. A first wear ring 71 and a second wear ring 72 are mounted in the first mounting groove 66 and the second mounting groove 67, respectively. The first wear ring 71 and the second wear ring 72 are made of a resin with excellent sliding properties, such as polytetrafluoroethylene. A seal member 73 is mounted in the seal groove 68. The seal member 73 is, for example, a lip seal. This divides the interior of the accommodating bore 13 into a pressure adjustment chamber 74 between the bottom of the accommodating bore 13 and the piston 52, and a decompression chamber 75 between the piston 52 and the cover 51. The pressure adjustment chamber 74 is a space at the back of the accommodating bore 13, to which the primary flow path 11 and the secondary flow path 12 open. The decompression chamber 75 is a space on the opening side of the accommodating bore 13, and is open to the atmosphere, for example.

[0026] The pin 62 has a sliding portion 81, a downstream end portion 82 protruding from one end of the sliding portion 81, and an upstream end portion 83 protruding from the other end of the sliding portion 81. The sliding portion 81 is, for example, cylindrical. The outer diameter of the sliding portion 81 is slightly smaller than the inner diameter of the plug hole 46. This allows the pin 62 to slide within the plug hole 46. The sliding portion 81 has multiple flow path holes 84 penetrating it in the axial direction. The multiple flow path holes 84 are, for example, arranged at equal angular intervals around the central axis of the sliding portion 81. The downstream end portion 82 and the upstream end portion 83 are, for example, cylindrical. The outer diameter of the upstream end portion 83 is approximately equal to the outer diameter of the abutment portion 43 of the valve disc 31. The pin 62 is housed in the plug hole 46 so that the downstream end portion 82 abuts against the third portion 65 of the piston 52 and the upstream end portion 83 abuts against the abutment portion 43 of the valve disc 31.

[0027] The second biasing member 53 is, for example, a coil spring. One end of the second biasing member 53 abuts against the closed end of the cover 51, and the other end of the second biasing member 53 abuts against the first portion 63 of the piston body 61. In other words, the first portion 63 is subjected to the biasing force of the second biasing member 53. The second biasing member 53 is compressed between the cover 51 and the piston body 61. As a result, the second biasing member 53 biases the valve body 31 in a direction that separates it from the valve seat 32 via the piston 52, i.e., the piston body 61 and the pin 62.

[0028] As described above, the piston body 61 is constantly in contact with the pin 62 due to the biasing force of the second biasing member 53. In other words, the piston body 61 and the pin 62 do not normally separate from each other. Therefore, it can be said that the pin 62 extends from the third portion 65 of the piston body 61 toward the valve body 31. Furthermore, as described above, the outer diameter of the third portion 65 is larger than the inner diameter of the plug hole 46, and therefore the pin 62 is thinner than the third portion 65. In other words, the pin 62 corresponds to the fourth portion. Therefore, a part of the second portion 64, the third portion 65, and the pin 62, which is the fourth portion, are accommodated in the pressure adjustment chamber 74. The first portion 63 and the remaining portions of the second portion 64 are accommodated in the decompression chamber 75.

[0029] In the pressure reducing valve 1 configured as described above, the piston 52 slides within the accommodation cavity 13 in response to the pressure difference between the pressure in the pressure adjustment chamber 74 and the pressure in the pressure reduction chamber 75 and the biasing forces of the first biasing member 34 and the second biasing member 53. The opening amount of the valve mechanism 5, or more specifically, the flow path cross-sectional area between the head portion 42 of the valve element 31 and the valve port 45 of the valve seat 32, changes depending on the position of the piston 52. The hydrogen gas flowing through the primary flow path 11 is decompressed in response to the opening amount of the valve mechanism 5, enters the pressure adjustment chamber 74, and is delivered from the secondary flow path 12. When the secondary pressure, which is the pressure within the pressure adjustment chamber 74, reaches a predetermined pressure, the valve element 31 seats on the valve seat 32. This restricts excessive inflow of hydrogen gas into the pressure adjustment chamber 74, preventing the pressure of the gas delivered from the secondary flow path 12 from exceeding the predetermined pressure.

[0030] (Functions and Effects of the Present Embodiment) Next, the functions and effects of the present embodiment will be described. (1-1) The piston 52 has a first portion 63, a second portion 64 that is thinner than the first portion 63, a third portion 65 that is thinner than the second portion 64, and a fourth portion, the pin 62, that is thinner than the third portion 65. The interior of the accommodation hole 13 is partitioned into a pressure adjustment chamber 74 and a decompression chamber 75 by a seal member 73 provided on the outer periphery of the second portion 64. A part of the second portion 64, the third portion 65, and the fourth portion, the pin 62, are disposed in the pressure adjustment chamber 74, and the first portion 63 and the remaining portions of the second portion 64 are disposed in the decompression chamber 75.

[0031] According to the above configuration, the piston 52 receives the pressure in the pressure adjustment chamber 74 at a narrow portion of the piston 52. Specifically, the pressure-receiving area of ​​the piston 52 that receives the pressure in the pressure adjustment chamber 74, i.e., the pressure-receiving area of ​​the piston 52 that receives the pressure in the direction opposite to the biasing direction of the second biasing member 53, is an area corresponding to the thickness (outer diameter) of the second portion 64. Meanwhile, the piston 52 receives the biasing force of the second biasing member 53 at the first portion 63, which is a thick portion separate from the portion that receives the pressure in the pressure adjustment chamber 74. As described above, the piston 52 of this embodiment has a stepped structure, so the pressure-receiving area that receives the pressure in the pressure adjustment chamber 74 can be independently changed. Therefore, for example, by narrowing the second portion 64 without changing the thickness of the first portion 63, it is possible to set a high predetermined pressure while maintaining the biasing force of the second biasing member 53. In other words, a pressure reducing valve 1 that delivers hydrogen gas at a high secondary pressure can be realized while suppressing an increase in the biasing force of the second biasing member 53.

[0032] Furthermore, the piston 52 has a third portion 65. Here, assuming a comparative example without the third portion 65, i.e., a comparative example in which the pin 62 (the fourth portion) extends from the second portion 64, the volume of the pressure adjustment chamber 74 can be reduced compared to such a configuration. The volume of the pressure adjustment chamber 74 is the volume of the pressure adjustment chamber 74 portion of the accommodation hole 13 minus the volume of the piston 52 located within the pressure adjustment chamber 74. This makes it easier for the pressure in the pressure adjustment chamber 74 to decrease when hydrogen gas delivered from the secondary-side flow path 12 is consumed while the pressure reducing valve 1 is closed. Therefore, the pressure reducing valve 1 can be quickly switched to an open state, preventing an excessive decrease in the secondary pressure. Furthermore, when hydrogen gas flows in from the primary-side flow path 11 while the pressure reducing valve 1 is open, the pressure in the pressure adjustment chamber 74 tends to increase. Therefore, the pressure reducing valve 1 can be quickly switched to a closed state, preventing an excessive increase in the secondary pressure.

[0033] (1-2) The piston 52 includes a piston body 61, which is formed by integrating a first portion 63, a second portion 64, and a third portion 65, and a pin 62, which is a separate member from the piston body 61. If the piston 52 is tilted within the bore 13, the valve element 31 may not be pushed straight along its axis when the pressure reducing valve 1 is opened, and the size of the gap formed between the valve element 31 and the valve opening 45 of the valve seat 32 may become non-uniform in the circumferential direction. As a result, for example, abnormal noise may occur in the pressure reducing valve 1. To make the gap between the valve element 31 and the valve seat 32 uniform around the entire circumference, it is necessary to strictly control the dimensional accuracy of the piston 52 so that the piston 52 does not tilt within the bore 13. However, strictly controlling the dimensional accuracy of the entire piston 52 increases manufacturing costs. In this regard, in the above-described configuration, the pin 62, which abuts against the valve element 31, is a separate member from the piston body 61, and therefore, only the dimensional accuracy of the pin 62 needs to be strictly controlled. Therefore, compared to when the dimensional accuracy of the entire piston 52 is strictly controlled, it is possible to suppress an increase in manufacturing costs and to suppress the generation of abnormal noise.

[0034] (1-3) The accommodation hole 13 has a large hole portion 21 that accommodates the first portion 63, and a middle hole portion 22 that accommodates the second portion 64 and the third portion 65. The secondary-side flow path 12 opens into the inner circumferential surface of the middle hole portion 22 so as to face the third portion 65 in the radial direction.

[0035] According to the above configuration, the secondary side flow path 12 faces the third part 65, which is thinner than the second part 64, so that the fourth part, the pin 62, can be shortened while preventing the secondary side flow path 12 from being blocked by the piston 52.

[0036] Second Embodiment Next, a second embodiment of the pressure reducing valve will be described with reference to the drawings. For the sake of convenience, the same components as those in the first embodiment will be denoted by the same reference numerals, and the description thereof will be omitted.

[0037] 3, the piston 52 of this embodiment is a single member that is configured as a continuous, integrated unit. The piston 52 has a first portion 91, a second portion 92, a third portion 93, and a fourth portion 94. The first portion 91, the second portion 92, and the third portion 93 have the same configurations as the first portion 63, the second portion 64, and the third portion 65 of the first embodiment, respectively.

[0038] The fourth portion 94 has, for example, a cylindrical shape. The outer diameter of the fourth portion 94 is smaller than the inner diameter of the plug hole 46. When the piston 52 slides in the accommodation hole 13, the fourth portion 94 does not come into contact with the inner circumferential surface of the plug hole 46. The tip of the fourth portion 94 abuts against the abutment portion 43 of the valve body 31.

[0039] The piston 52 of this embodiment is manufactured by cutting a continuous cylindrical material without any gaps. In addition to the same effects and advantages as those of (1-1) and (1-3) of the first embodiment, this embodiment also provides the following effects and advantages.

[0040] (2-1) The piston 52 is a single member in which the first portion 91, the second portion 92, the third portion 93, and the fourth portion 94 are integrated. This configuration allows for a reduction in the number of parts compared to a piston 52 having multiple components. Furthermore, since the piston 52 includes the third portion 93, the fourth portion 94 can be shortened by the length of the third portion 93 compared to a piston of another comparative example in which the fourth portion 94 extends continuously from the second portion 92, i.e., a piston that does not include the third portion 93. Therefore, when a load acts on the tip of the fourth portion 94, the bending moment generated at the base end of the fourth portion 94 can be reduced. Therefore, the piston 52 is less susceptible to damage compared to a piston of another comparative example that does not include the third portion 93.

[0041] In particular, in this embodiment, the secondary-side flow passage 12 opens to the inner circumferential surface of the accommodation hole 13, and therefore, in the case of the piston of the comparative example, the fourth portion 94 tends to be long so that the opening of the secondary-side flow passage 12 is not blocked by the second portion 92. Therefore, the effect of the piston 52 having the third portion 93 is significant.

[0042] (2-2) The piston 52 is a continuous, one-piece component manufactured by cutting a cylindrical material. With the above configuration, the amount of cutting required from the cylindrical material is reduced compared to the piston of the comparative example that does not have the third portion 93, making the piston 52 easier to machine.

[0043] The above-described embodiments can be modified as follows. The above-described embodiments and the following modifications can be combined with each other to the extent that no technical contradiction occurs. In the above-described embodiments, the cover 51 is fixed to the large hole portion 21 by screw fastening, but this is not limited to this. For example, the cover 51 may be fixed to the large hole portion 21 by press-fitting. Similarly, the plug 33 may be fixed to the small hole portion 23 by press-fitting.

[0044] In each of the above-described embodiments, the opening positions of the primary flow passage 11 and the secondary flow passage 12 relative to the accommodation hole 13 may be changed as appropriate. For example, the secondary flow passage 12 may open to the bottom surface of the accommodation hole 13.

[0045] In the second embodiment, at least one of the first portion 91, the second portion 92, the third portion 93, and the fourth portion 94 may be formed from a separate member and integrated with the other portions by fastening with screws or the like. In other words, the first portion 91, the second portion 92, the third portion 93, and the fourth portion 94 do not have to be a continuous, uninterrupted, one-piece product. Similarly, in the first embodiment, at least one of the first portion 63, the second portion 64, and the third portion 65 may be formed from a separate member and integrated with the other portions by fastening with screws or the like.

[0046] In the above embodiments, the first biasing member 34 and the second biasing member 53 are coil springs, but they are not limited to this and may be other biasing members, such as disc springs. In the first embodiment, the cross-sectional shape of the piston 52 (piston body 61 and pin 62) is circular, but they are not limited to this and may be elliptical or polygonal, for example. Similarly, in the second embodiment, the cross-sectional shape of the piston 52 may be elliptical or polygonal, for example. The cross-sectional shape of the accommodation hole 13 is changed depending on the cross-sectional shape of the piston 52.

[0047] In the above-described embodiments, the pressure reducing valve 1 reduces the pressure of high-pressure hydrogen gas. However, the present invention is not limited to this, and the pressure reducing valve 1 may reduce the pressure of high-pressure gases other than hydrogen.

Claims

1. A pressure reducing valve comprising: a body having a gas flow path including a primary side flow path and a secondary side flow path, and accommodation holes connected to each of the primary side flow path and the secondary side flow path; a valve seat provided in the primary side flow path; a valve disc slidably received in the primary side flow path; a cover fixed to the accommodation hole; a piston slidably received in the accommodation hole and in contact with the valve disc; a biasing member disposed between the piston and the cover and configured to bias the valve disc in a direction away from the valve seat via the piston; and a seal member provided on the outer periphery of the piston, wherein the piston has: a first portion configured to receive the biasing force of the biasing member; a second portion extending from the first portion toward the valve disc and being thinner than the first portion; a third portion extending from the second portion toward the valve disc and being thinner than the second portion; and a fourth portion extending from the third portion toward the valve disc and being thinner than the third portion, the fourth portion in contact with the valve disc, a pressure reducing valve in which the sealing member is disposed on the outer periphery of the second portion, so that the interior of the accommodating hole is divided into a pressure adjustment chamber between the bottom of the accommodating hole and the piston, and a pressure reduction chamber between the piston and the cover, the primary side flow path and the secondary side flow path open into the pressure adjustment chamber, and a part of the second portion, the third portion, and the fourth portion are disposed in the pressure reduction chamber, and the first portion and the remaining portions of the second portion are disposed in the pressure reduction chamber.

2. A pressure reducing valve as claimed in claim 1, wherein the piston comprises: a piston body in which the first part, the second part and the third part are integrated; and a pin which is a separate member from the piston body and is the fourth part.

3. A pressure reducing valve according to claim 1, wherein the piston is a single member in which the first portion, the second portion, the third portion, and the fourth portion are integrated.

4. A pressure reducing valve according to any one of claims 1 to 3, wherein the accommodation hole has a large hole portion in which the first portion is accommodated and a middle hole portion in which the second portion and the third portion are accommodated, and the secondary side flow path opens onto the inner circumferential surface of the middle hole portion so as to face the third portion.

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