JP2013206360A - Decompression device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a decompression device capable of achieving miniaturization and cost reduction.SOLUTION: By a difference between a pressure of a fluid introduced into a flow path and elastic restoration force of an elastic member 58, a piston 55 is moved along a prescribed moving direction. By the movement of the piston 55, an on-off valve is opened and closed, and the pressure of the fluid is reduced from a high pressure to a low pressure which is a prescribed adjustment value. When setting the adjustment value, the magnitude of the elastic restoration force of the elastic member 58 is adjusted. In a decompression device 11 of the present invention, the elastic restoration force of the elastic member 58 is easily adjusted by adjusting a screw-in amount of a cover member 14. Thus, since there is no need of assembling an adjustment screw or a screw receiving member as before, the decompression device 11 at a low cost is achieved by reducing the number of components.

Description

  The present invention relates to a pressure reducing device that reduces the pressure of a fluid from a high pressure to a low pressure.

  For example, the decompression device described in Patent Document 1 includes a main body member, a cover member coupled to the main body member, and a fluid or gas flow path extending from an input port to an output port of the main body member. A piston is disposed in a cylinder formed in the cover member so as to be able to reciprocate. A piston spring is disposed in the piston, and the piston reciprocates due to the difference between the elastic restoring force of the piston spring and the pressure of the gas in the flow path. By such reciprocating movement of the piston, the on-off valve arranged in the flow path repeatedly opens and closes, and the high-pressure gas flowing in from the input port is reduced to a low pressure and flows out from the output port.

JP 2011-108057 A

  Since the piston spring has variations in the spring constant and dimensions, an adjustment screw is incorporated in the cover member in order to adjust the elastic restoring force of the piston spring to a predetermined value. A spring receiving member disposed in the cylinder and receiving a piston spring is connected to the adjustment screw. The piston spring is disposed in a bottomed hole formed in the piston and is sandwiched between the piston and the spring receiving member. The elastic restoring force of the piston spring is adjusted by moving the position of the spring receiving member by adjusting the screwing amount of the adjusting screw. However, such an adjusting screw and a spring receiving member increase the number of parts, which increases the cost.

  Moreover, the cover member includes a cylindrical portion that forms a cylinder, and a flange portion that spreads outward from, for example, the lower end portion of the cylindrical portion, and is fixed to the main body member via a bolt at the flange portion. . According to such a configuration, in the decompression device, the size increases due to the spread of the flange portion, while the mass and cost increase due to an increase in the number of parts such as bolts. In addition, the decompression device cannot be reduced in size due to the spread of the flange portion, which may limit the degree of freedom of mounting on a vehicle such as an automobile.

  This invention is made | formed in view of the said situation, Comprising: It aims at providing the decompression device which can implement | achieve size reduction and low cost.

In order to achieve the above object, according to the present invention,
A pressure reducing device for reducing the pressure of a fluid from a high pressure to a low pressure,
A housing body forming a fluid flow path;
An on-off valve that is disposed in the flow path and switches between opening and closing of the flow path by opening and closing;
A piston that is arranged so as to be reciprocally movable in a predetermined movement direction within the housing body, and that opens and closes the on-off valve by reciprocating movement;
A cover member coupled to the housing body by being screwed into the housing body along the moving direction;
An elastic member disposed between the cover member and the piston and exhibiting an elastic restoring force to move the cover member and the piston away from each other along the moving direction;
The cover member is provided with a pressure reducing device capable of adjusting an elastic restoring force of the elastic member by adjusting a screwing amount along the moving direction.

  In such a pressure reducing device, the piston moves along a predetermined moving direction due to the difference between the pressure of the fluid introduced into the flow path and the elastic restoring force of the elastic member. The on / off valve is opened and closed by the movement of the piston, and the pressure of the fluid is reduced from a high pressure to a low pressure that is a predetermined adjustment value. In setting the adjustment value, the magnitude of the elastic restoring force of the elastic member is adjusted. In the decompression device of the present invention, the elastic restoring force of the elastic member can be easily adjusted by adjusting the screwing amount of the cover member. Therefore, since there is no need to incorporate an adjusting screw or a spring receiving member as in the prior art, a low-cost decompression device can be realized by reducing the number of parts.

  Moreover, by connecting the cover member to the housing main body by screwing, the conventional flange portion and bolt of the cover member are not required, so that a lower cost decompression device can be realized. Further, in the conventional pressure reducing device, the flange portion protrudes, for example, in a direction orthogonal to the vertical axis, and therefore the size of the cover member, that is, the pressure reducing device can be reduced by omitting the formation of the flange portion. As a result, the degree of freedom of mounting the decompression device on a vehicle such as an automobile can be improved.

  In the decompression device as described above, screwing may be established between the outer peripheral surface of the cover member and the inner peripheral surface of the housing body. On the other hand, screwing may be established between the inner peripheral surface of the cover member and the outer peripheral surface of the housing body.

  When screwing is established between the outer peripheral surface of the cover member and the inner peripheral surface of the housing body, the decompression device is screwed to the outer peripheral surface of the cover member along the moving direction, thereby the cover. A lock member coupled to the member and received by the edge of the housing body may be further provided to prevent the cover member from loosening with respect to the housing body.

  In such a pressure reducing device, the lock member is received by the edge of the housing body, and the cover member can be prevented from loosening with respect to the housing body. Therefore, since the occurrence of a change in elastic restoring force of the elastic member can be prevented during the operation of the decompression device, the decompression accuracy can be maintained in the decompression device.

  As described above, according to the present invention, it is possible to provide a decompression device that can achieve downsizing and low cost.

1 is a vertical sectional view schematically showing the structure of a decompression device according to a first embodiment of the present invention. It is a partial expanded vertical sectional view of a housing body. It is a top view which shows roughly the structure of the cover member which concerns on one specific example. FIG. 4 is a partial cross-sectional view taken along line 4-4 of FIG. FIG. 5 is a plan view schematically showing a structure of a cover member according to a modification, corresponding to FIG. 3. It is a vertical sectional view which shows roughly the structure of the decompression device concerning a 2nd embodiment of the present invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a vertical sectional view schematically showing the structure of the decompression device 11 according to the first embodiment of the present invention. The decompression device 11 is mounted on a fuel cell system such as a fuel cell vehicle. The decompression device 11 is a high pressure (for example, 3.1 to 87.6 MPa (abs)) fluid, that is, hydrogen gas supplied from a fuel tank (not shown), ie, a low pressure (for example, 1.1 to 2.1 MPa (abs)). This is a piston type pressure reducing valve that is decompressed to be supplied to a fuel cell stack (not shown).

  As shown in FIG. 1, the housing 12 of the decompression device 11 includes a housing body 13 that forms a hydrogen gas flow path, and a cylindrical cover member 14 that is coupled to the open end of the upper end of the housing body 13. ing. A joint (not shown) that forms an upstream port is attached to the lower end of the housing body 13, and a joint (not shown) that forms a downstream port is attached to the side surface of the housing body 13. The upstream port and the downstream port are in fluid communication with each other via a flow path in the housing 12. Details of the flow path will be described later.

  The housing body 13 includes a first hole 17, a second hole 18 continuous with the first hole 17, and a second hole 18 extending upward from the lower end side to the upper end side of the housing body 13 along the longitudinal axis X of the housing 12. A third hole 19 that continues to the second hole 18, a fourth hole 20 that continues to the third hole, and a fifth hole 21 that continues to the fourth hole 20 are formed. The first hole 17 is opened downward from the lower end of the housing body 13, while the fifth hole 21 is opened upward from the upper end of the housing body 13. The first hole 17 to the fifth hole 21 are formed from a coaxial cylindrical space having the longitudinal axis X as the central axis.

  FIG. 2 is a partially enlarged vertical sectional view of the housing body 13. Referring also to FIG. 2, the upstream end of the first hole 17 is connected to a fuel tank (not shown) via a pipe (not shown). A cylindrical valve body 34 is disposed in the second hole 18 so as to be reciprocally movable in the vertical direction in the second hole 18 along the vertical axis X. The valve body 34 includes a cylindrical portion 35 formed in a cylindrical shape along the longitudinal axis X, and a tapered portion 36 that is connected to the upper end of the cylindrical portion 35 and tapers toward the upper end. When the valve body 34 moves up and down along the vertical axis X, the cylindrical outer peripheral surface of the cylindrical portion 35 slides on the cylindrical inner peripheral surface of the second hole 18.

  The valve body 34 includes a bottomed hole 37 that is opened downward. The bottomed hole 37 accommodates an elastic member, that is, a valve spring 38. The valve spring 38 is disposed between the bottom surface of the bottomed hole 37 and the step surfaces of the first hole 17 and the second hole 18, and is elastically restored in the direction of moving the valve body 34 away from the step surface along the vertical axis X. Demonstrate power. A plurality of flow path grooves 41 extending in parallel to the vertical axis X from the upper end to the lower end of the cylindrical portion 35 are formed on the cylindrical outer peripheral surface of the cylindrical portion 35. A flow path of hydrogen gas is formed between the flow path groove 41 and the cylindrical inner peripheral surface of the second hole 18.

  The upper end of the tapered portion 36 of the valve body 34 is received by an annular valve seat 42 disposed in the third hole 19 by the elastic restoring force of the valve spring 38. The valve seat 42 includes a through hole 43 that defines an inner peripheral surface that partially matches the contour of the tapered portion 36 of the valve body 34. The valve body 34 and the valve seat 42 constitute an on-off valve of the decompression device 11. When the tapered portion 36 of the valve body 34 is pressed against the valve seat 42 and the through hole 43 is closed, the on-off valve is closed. On the other hand, when the tapered portion 36 is separated from the valve seat 42 and the through hole 43 is opened, the on-off valve is opened. In this way, closing and opening of the flow path are switched.

  A cylindrical valve seat fixing member 44 is fixed to the fourth hole 20. The valve seat fixing member 44 is fixed to the fourth hole 20 by the male screw on the cylindrical outer peripheral surface of the valve seat fixing member 44 meshing with the female screw on the cylindrical inner peripheral surface of the fourth hole 20. When the valve seat fixing member 44 is fixed in the fourth hole 20 in this way, the lower end surface of the valve seat fixing member 44 is received by the upper end surface of the valve seat 42. As a result, the valve seat 42 is fixedly disposed in the third hole 19 by screwing the valve seat fixing member 44.

  A cylindrical through hole 45 is formed in the valve seat fixing member 44 along the vertical axis X. A cylindrical valve stem 46 is disposed in the through hole 45 so as to be reciprocally movable in the vertical direction in the through hole 45 along the vertical axis X. The valve stem 46 includes a cylindrical portion 47 and a tapered portion 48 that is connected to the lower end of the cylindrical portion 47 and tapers toward the lower end. Since the lower end of the taper part 48 is received by the upper end of the valve body 34, the vertical movement of the taper part 48 along the vertical axis X is similarly interlocked with the vertical movement of the valve body 34 along the vertical axis X.

  When the valve stem 46 moves up and down along the vertical axis X, the cylindrical outer peripheral surface of the columnar portion 47 slides on the cylindrical inner peripheral surface of the through hole 45. A plurality of flow passage grooves 49 extending in parallel with the vertical axis X from the upper end to the lower end of the columnar portion 47 are formed on the cylindrical outer peripheral surface of the columnar portion 47. The flow path 49 forms a hydrogen gas flow path between the through hole 45 and the cylindrical inner peripheral surface.

  The cover member 14 is screwed into the housing main body 13 when a male screw formed on the outer peripheral surface of the cylinder and a female screw formed on the inner peripheral surface of the fifth hole 21 are engaged with each other. An annular groove 51 is formed around the longitudinal axis X on the cylindrical outer peripheral surface of the cover member 14, and an O-ring 52 is disposed in the annular groove 51. The O-ring 52 may be formed from an elastic material such as rubber. The O-ring 52 is pressed against the cylindrical inner peripheral surface of the fifth hole 21 by its elastic deformation, thereby ensuring the airtightness of the flow path.

  On the other hand, the lock nut 53 is screwed into the cover member 14 when the male screw formed on the cylindrical outer peripheral surface of the cover member 14 and the female screw formed on the cylindrical inner peripheral surface of the lock member 53 are engaged. Is done. When the lock nut 53 rotates around the vertical axis X and is screwed into the cover member 14, the lock nut 53 is received by the edge of the open end of the housing body 13. As a result, the lock nut 53 restricts the rotation of the cover member 14 around the vertical axis X and prevents the cover member 14 from loosening.

  The cover member 14 has a cylindrical bottomed hole 54 opened downward. A cylindrical piston 55 is disposed in the bottomed hole 54 so as to be vertically movable along the vertical axis X. Thus, the cover member 14 constitutes a cylinder. When the piston 55 moves up and down along the vertical axis X, the cylindrical outer peripheral surface of the piston 55 slides on the cylindrical inner peripheral surface of the cover member 14. On the upper end surface of the pedestal fixing member 44, a plurality of streak channel grooves 56 extending in a direction orthogonal to the vertical axis X are formed, and the channel grooves 56 are connected to the channel grooves 49. By this flow channel groove 56, a hydrogen gas flow channel is formed between the bottom surface of the piston 55.

  The piston 55 has a cylindrical bottomed hole 57 opened upward in the inside thereof. An elastic member, that is, a piston spring 58 is disposed in the bottomed hole 57. The piston spring 58 is disposed between the bottom surface of the bottomed hole 54 of the cover member 14 and the bottom surface of the bottomed hole 57 of the piston 55, and moves the cover member 14 and the piston 55 away from each other along the vertical axis X. Exhibits elastic restoring force. Since the bottom surface of the piston 55 is received by the upper end of the valve stem 46, the piston 55 presses the valve stem 46 toward the valve member 34.

  A plurality of annular grooves 59 are formed around the longitudinal axis X on the cylindrical outer peripheral surface of the piston 55, and an O-ring 61 and wear rings 62 and 62 are individually arranged in each annular groove 59. The O-ring 61 may be made of an elastic material such as rubber (NBR), and the wear ring 62 may be made of Teflon (registered trademark), for example. The O-ring 61 is pressed against the inner peripheral surface of the cylinder of the cover member 14 by elastic deformation, thereby ensuring the airtightness of the flow path.

  A flow path hole (not shown) connected to the joint of the downstream port is connected to the fifth hole 21 at a position different from that of the fourth hole 20. A fuel cell stack (not shown) is connected to the flow path hole via a pipe (not shown). By providing either a face seal or a shaft seal between the joint and the housing body 13, the airtightness of the flow path is ensured.

  In the decompression device 11 as described above, the first hole 17, the second hole 18, the flow channel 41, the through hole 43, the through hole 45, the flow channel 49, the flow channel 56, the fifth hole 21, and the flow channel hole. By forming a hydrogen gas flow path in the housing body 13, hydrogen gas can flow from the upstream port to the downstream port. At this time, as will be described later, the pressure of the hydrogen gas is reduced from a high pressure to a low pressure by opening and closing the on-off valve.

  Here, the housing main body 13, the cover member 14, and the piston 55 may be formed by forging aluminum such as A6061-T6. Costs can be reduced by changing the material of these components from conventional stainless steel to aluminum. Further, the manufacturing can be facilitated by changing the manufacturing method from conventional total shaving to forging. On the other hand, the valve body 34 and the joints 15 and 16 may be formed from stainless steel.

  The surface of the housing body 13, the cover member 14, and the piston 55 may be subjected to a surface strengthening process such as an alumite process that oxidizes the aluminum surface. According to this process, it is possible to prevent galling due to sliding between the cylindrical outer peripheral surface of the valve body 34 and the cylindrical inner peripheral surface of the second hole 18 of the housing body 13. As a result, conventionally, separate guide members that function as guides for the valve body can be reduced, and the number of parts can be reduced.

  FIG. 3 is a plan view schematically showing the structure of the cover member according to one specific example. Referring also to FIG. 3, the protrusion 14 a formed at the upper end of the cover member 14 has, for example, a hexagonal column shape outline. A recess 65 is formed in the protrusion 14 a along the vertical axis X, and a through-hole 66 is similarly formed along the vertical axis X in the bottom of the recess 65. A cap 67 is attached to the through hole 66. The cap 67 prevents the inflow of liquid such as water into the cover member 14 while introducing the atmosphere into the cover member 14. Thus, the space inside the cover member 14 is maintained at atmospheric pressure.

  4 is a partial sectional view taken along line 4-4 of FIG. Referring also to FIG. 4, the upper end surface of the cap 67 is disposed inside the recess 65 from the upper end surface of the protrusion 14a. A slit 68 extending from the inner edge connected to the recess 65 to the outer edge connected to the outer peripheral surface of the cover member 14 is formed at the upper end of the cover member 14. The slit 68 is not formed at the corner of the hexagonal column in the outline of the protrusion 14a, but is formed at the surface between the corners adjacent to each other. The bottom surface of the slit 68 is formed from an inclined surface that approaches the lower end of the housing body 13 as the distance from the vertical axis X increases in the direction intersecting the vertical axis X.

  As is clear from FIG. 4, the upper end surface of the protrusion 14 a is the highest in the direction along the vertical axis X, and then gradually decreases in the order of the upper end surface of the cap 67, the bottom surface of the recess 65, and the outer edge of the slit 68. To go. Note that slits 68 may be formed in some of the hexagonal contour surface portions. Moreover, as shown in FIG. 5, the outline of the protrusion 14a of the cover member 14 may be cylindrical. At this time, a plurality of slits 68 may be formed radially from the recess 65. In the present embodiment, four slits 68 are formed around the longitudinal axis X at an equiangular interval of, for example, 90 degrees.

  According to such a configuration, the cap 67 is completely accommodated in the recess 65, and the upper end surface of the cap 67 is disposed inside the recess 65 from the upper end surface of the protrusion 14a. An increase in size can be avoided. At the same time, since the recess 65 and the slit 68 are formed in the cover member 14, the cover member 14 can be reduced in weight. As a result, since the material cost of the cover member 14 can be suppressed, the manufacturing cost of the cover member 14 and thus the decompression device 11 can be suppressed.

  Moreover, since the decompression device 11 is disposed, for example, adjacent to the cover on the bottom surface of the vehicle, rainwater and pebbles may hit the decompression device 11 directly through gaps and drain holes formed in the cover. However, since the cap 67 is disposed in the recess 65, it is possible to avoid direct hit of rainwater or pebbles on the cap 67. Moreover, even if rainwater or pebbles enter the depression 65, the rainwater or pebbles are discharged from the slit 68 to the outside of the decompression device 11. As a result, for example, corrosion of the cap 67 can be prevented.

  Next, the operation of the decompression device 11 will be briefly described. Since the elastic restoring force of the piston spring 58 is set to be larger than the elastic restoring force of the valve spring 38, the through hole 43 of the valve seat 42 is opened by the piston spring 58 pressing the valve stem 46 downward on the bottom surface. Is done. At this time, high-pressure hydrogen gas supplied from the fuel tank via the pipe is introduced into the second hole 18 via the first hole 17. The hydrogen gas introduced into the second hole 18 passes through the channel groove 41, the through hole 43, the through hole 45, the channel groove 49, the channel groove 56, the fifth hole 21 and the channel hole of the valve element 34. Sent to the fuel cell stack.

  In the decompression device 11, the cylinder space of the cover member 14 is partitioned by the piston 55 into an adjustment chamber 71 that houses the piston spring 58 and a decompression chamber 72 on the opposite side across the piston 55. In the decompression device 11, the pressure in the decompression chamber 72 is increased by the high-pressure hydrogen gas supplied from the fuel tank. As a result, when the sum of the elastic restoring force of the valve spring 38 and the pressure of the hydrogen gas exceeds the elastic restoring force of the piston spring 58, the piston 55 moves upward along the vertical axis X. As the piston 55 moves, the valve stem 46 and the valve body 34 move upward. As a result, the valve body 34 sits on the valve seat 42 and closes the through hole 43, whereby the closed state is established.

  In the closed state, the introduction of hydrogen gas into the decompression chamber 72 is stopped, while the hydrogen gas in the decompression chamber 72 is discharged toward the fuel cell stack through the flow path hole 63. The pressure drops. When the elastic restoring force of the piston spring 58 exceeds the sum of the elastic restoring force of the valve spring 38 and the pressure of hydrogen gas due to the decrease in the pressure in the decompression chamber 72, the piston 55 moves downward along the vertical axis X. As a result, as a result of the valve stem 46 and the valve body 34 moving downward, the valve body 34 is detached from the valve seat 42 to open the through hole 43, and an open state is established.

  In the open state, since the introduction of the high-pressure hydrogen gas into the decompression chamber 72 is resumed, the pressure in the decompression chamber 72 is increased again by the high-pressure hydrogen gas supplied from the fuel tank. By continuing the introduction of the high-pressure hydrogen gas in this way, the pressure in the decompression chamber 72 is repeatedly increased and decreased, that is, the piston 55 is moved up and down repeatedly. As a result, the high-pressure hydrogen gas supplied from the fuel tank is depressurized to a predetermined adjustment value, and the hydrogen gas having the predetermined adjustment value is supplied to the fuel cell stack.

  In the pressure reducing device 11 as described above, the pressure adjustment value can be set by changing the magnitude of the elastic restoring force of the piston spring 58. For this setting, it is necessary to adjust the height of the piston spring 58 in the direction along the vertical axis X. In the present invention, the height of the piston spring 58 can be directly adjusted by adjusting the screwing amount of the cover member 14 relative to the housing body 13 in the direction along the longitudinal axis X. As a result, since there is no need to incorporate an adjusting screw or a spring receiving member as in the prior art, a low-cost decompression device 11 can be realized by reducing the number of parts.

  In addition, by connecting the cover member 14 to the housing body 13 by screwing, the conventional flange portion and bolt of the cover member are not required, so that the low-pressure decompression device 11 can be realized. Further, since the flange portion projects, for example, in a direction orthogonal to the vertical axis, the size of the cover member 14, that is, the decompression device 11 can be reduced by omitting the formation of the flange portion. As a result, the degree of freedom of mounting the decompression device 11 on a vehicle such as an automobile can be improved.

  Furthermore, in the decompression device 11 of the present invention, the lock nut 53 is screwed onto the cylindrical outer peripheral surface of the cover member 14, and the lock nut 53 is received by the edge of the open end of the housing body 13. As a result, since the rotation of the cover member 14 around the vertical axis X with respect to the housing body 13 can be restricted, the cover member 14 can be prevented from loosening. Therefore, since the occurrence of a change in the height of the piston spring 58 can be prevented during the operation of the decompression device 11, the decompression accuracy can be maintained in the decompression device 11.

  In screwing the cover member 14, in the embodiment of FIG. 4, a normal tool is mounted on the hexagonal column-shaped protrusion 14 a of the cover member 14. The screw amount of the cover member 14 is adjusted by this normal tool. On the other hand, in the embodiment of FIG. 5, a special tool that engages with the slit 68 formed in the cylindrical protrusion 14a must be used. As a result, since the screwing amount of the cover member 14 cannot be easily adjusted, it is possible to prevent the screwing amount from being erroneously adjusted.

  FIG. 6 is a partial vertical sectional view schematically showing the structure of the decompression device 11 according to the second embodiment of the present invention. In the decompression device 11, the cover member 14 is screwed into the housing main body 13 by meshing with the male screw on the cylindrical outer peripheral surface of the cylindrical wall 73 formed on the housing main body 13 with a female screw on the inner peripheral surface of the cylinder. On the other hand, the piston 55 is disposed in the cylindrical wall 73 so as to be capable of reciprocating in the vertical direction along the vertical axis X, and slides on the cylindrical inner peripheral surface of the cylindrical wall 73. Like reference numerals are attached to the structure or components equivalent to those of the aforementioned first embodiment. Such a decompression device 11 can also achieve the same effects as described above.

11 Pressure reducing device 13 Housing body 14 Cover member 53 Lock member (lock nut)
55 Piston 58 Elastic member (piston spring)

Claims (4)

A pressure reducing device for reducing the pressure of a fluid from a high pressure to a low pressure,
A housing body forming a fluid flow path;
An on-off valve that is disposed in the flow path and switches between opening and closing of the flow path by opening and closing;
A piston that is arranged so as to be reciprocally movable in a predetermined movement direction within the housing body, and that opens and closes the on-off valve by reciprocating movement;
A cover member coupled to the housing body by being screwed into the housing body along the moving direction;
An elastic member disposed between the cover member and the piston and exhibiting an elastic restoring force to move the cover member and the piston away from each other along the moving direction;
The decompression device according to claim 1, wherein the cover member is capable of adjusting an elastic restoring force of the elastic member by adjusting a screwing amount along the moving direction.   2. The decompression device according to claim 1, wherein screwing is established between an outer peripheral surface of the cover member and an inner peripheral surface of the housing body.   3. The decompression device according to claim 2, wherein the housing body is coupled to the cover member by being screwed to an outer peripheral surface of the cover member along the moving direction, and is received by an edge of the housing body. A pressure reducing device, further comprising a lock member for preventing the cover member from loosening against.   2. The decompression device according to claim 1, wherein screwing is established between an inner peripheral surface of the cover member and an outer peripheral surface of the housing body.

Images