JP5453227B2 - Pressure reducing valve - Google Patents

Description

  The present invention relates to a pressure reducing valve that reduces a primary pressure to a lower secondary pressure.

  Conventionally, there is known a pressure reducing valve that reduces the primary pressure to a lower secondary pressure. The pressure reducing valve includes a housing and a piston, and a valve passage connected to the primary port and the secondary port is formed in the housing. A piston is movably provided in the housing, and the opening degree of the valve passage is adjusted by moving the piston.

  The piston is arranged so as to be able to receive the secondary pressure, and is moved in the closing direction for closing the valve passage by receiving the secondary pressure. The piston is provided with a spring member. The spring member urges the piston in a direction against the secondary pressure, that is, an opening direction that opens the valve passage, and the piston moves to a position where the urging force of the spring member and the secondary pressure are balanced. Thus, the secondary passage pressure is made constant by adjusting the opening of the valve passage (see, for example, Patent Document 1).

  In addition, the pressure reducing valve described in Patent Document 1 is divided into two pistons, the opening of the valve passage is adjusted by the pressure reducing piston that is one piston, and the secondary is driven by the drive piston that is the other piston. It is designed to receive pressure. The decompression piston and the drive piston are in contact with each other, and the opening of the valve passage is adjusted by pushing the decompression piston in accordance with the secondary pressure received by the drive piston.

JP 2006-146776 A

  In the pressure reducing valve described in Patent Document 1, a sheet member is provided at the tip of the pressure reducing piston, and a protruding piece is provided at a position facing the sheet member of the housing, and the sheet member is seated on the protruding piece. The valve passage is closed. In this pressure reducing valve, the driving piston and the pressure reducing piston are in contact with each other, and the secondary pressure received by the driving piston is directly transmitted to the pressure reducing piston. Therefore, when a large impact pressure such as a surge pressure is generated and the secondary pressure rises unexpectedly, an unexpected excessive driving force corresponding to the secondary pressure acts from the drive piston to the decompression piston. When such a driving force is applied, the sheet member at the tip of the decompression piston is pressed against the protruding piece with a large pressing force, the protruding piece bites into the sheet member, and the sheet member is greatly deformed. Then, the relationship between the position of the decompression piston and the opening of the valve passage changes, the control balance is lost, and the secondary pressure changes from the initially set value. Therefore, when an excessive secondary pressure is applied to the pressure reducing valve, its reliability and durability are low.

  Therefore, an object of the present invention is to provide a pressure reducing valve that can suppress deformation of a pressure reducing piston or a valve seat portion due to an excessive pressing force and is excellent in reliability and durability.

The pressure reducing valve of the present invention includes a housing having a valve passage connected to a primary port and a secondary port, a valve seat, a closed position provided in the housing, and seated on the valve seat to close the valve passage. A pressure reducing piston that moves between an open position for opening the valve passage and adjusts an opening degree of the valve passage; and a direction that is movable in the housing and is separated from the pressure reducing piston and is directed toward the pressure reducing piston A drive piston that receives the secondary pressure, a biasing member that applies a biasing force against the secondary pressure to the drive piston, and a pressure piston that is disposed between the pressure-reducing piston and the drive piston, and acts on the drive piston. elastic varying as the driving force by the secondary pressure which can absorb the driving force by the secondary pressure is pressed toward the closed position from the open position to the decompression piston is transmitted to the decompression piston A pressing member which is intended to include a.

  According to the present invention, when the secondary pressure to be received rises, the drive piston moves toward the pressure-reducing piston against the urging force, and pushes the pressing member with a force according to the driving force and the urging force by the secondary pressure. Through the pressure-reducing piston toward the closed position. Thereby, the opening degree of a valve channel | path can be adjusted to the opening degree according to secondary pressure, ie, a secondary pressure can be adjusted to the setting pressure according to urging | biasing force.

  Further, in the present invention, when an impact pressure such as surge pressure is introduced to the secondary port side and the secondary pressure becomes high, the decompression piston pushed by the drive piston is seated on the valve seat, and then the pressing member is Begins elastic deformation. As the pressing member is elastically deformed in this way, the pressing force transmitted to the decompression piston can be suppressed to the elastic restoring force of the pressing member (force to return to the original shape), and the pressing force is reduced to the impact pressure. It can be suppressed to a force lower than the acting force by. Thereby, the pressing force applied to the decompression piston and the valve seat portion can be suppressed, and deformation of the decompression piston and the valve seat portion can be suppressed. By suppressing the deformation of the pressure reducing piston and the valve seat in this way, it is possible to suppress the control balance from being lost, and it is possible to realize a pressure reducing valve excellent in reliability and durability.

  In the above invention, the pressing member preferably has an elastic coefficient larger than that of the urging member.

  If the said structure is followed, since a biasing member deform | transforms prior to a pressing member, the elastic deformation amount of the pressing member in the normal state where the excessive secondary pressure is not acting can be suppressed. Thereby, since the force acting on the drive piston can be transmitted to the decompression piston as it is, a decompression valve having excellent responsiveness during pressure regulation can be realized.

  In the above invention, one of the decompression piston and the valve seat has an annular projection piece, and the other of the decompression piston and the valve seat contacts the projection piece when the decompression piston moves to the closed position. It is preferable that a sheet member that closes the valve passage is provided, and the pressing member has an elastic coefficient smaller than an elastic coefficient of the sheet member.

  If the said structure is followed, a pressing member will deform | transform more largely with small force compared with a sheet | seat member. Therefore, the pressing member can absorb the pressing force after the seating, the amount of movement of the decompression piston can be made extremely small, and the deformation of the seat member can be prevented.

  In the above-mentioned invention, the stopper is provided in the housing and restricts movement of the drive piston in the direction toward the pressure-reducing piston, and the stopper is deformed when the pressure-reducing piston is located at a closed position. It is preferable that the movement of the drive piston is stopped so that the drive piston does not contact the pressure-reducing piston.

  According to the above configuration, it is possible to prevent the drive piston from directly contacting the pressure reducing piston after the pressure reducing piston is seated on the valve seat. Thereby, it can suppress that force larger than the elastic restoring force of a pressing member acts on a pressure reduction piston, and can prevent a deformation | transformation of a sheet | seat member. Further, by restricting the elastic deformation of the pressing member to a predetermined amount, the elastic restoring force of the pressing member (that is, the pressing force transmitted to the decompression piston) can be limited, and the deformation of the sheet member can be prevented.

  In the above invention, the housing is provided with an insertion member that penetrates the drive piston and is inserted into the decompression piston, and the valve passage is connected to the primary port by the decompression piston; The pressure reducing piston is partitioned into a secondary pressure chamber connected to a secondary port, and the decompression piston has a back pressure chamber closed by the insertion member, and a communication path connecting the back pressure chamber and the primary pressure chamber. The back pressure chamber is preferably formed so that the primary pressure guided to the back pressure chamber acts against the pressure reducing piston in a direction against the primary pressure of the primary pressure chamber.

  According to the above configuration, the primary pressure in the primary side pressure chamber received by the decompression piston can be canceled out by the primary pressure in the back pressure chamber, and the influence of fluctuations in the primary pressure can be suppressed. As a result, the secondary pressure can be regulated almost accurately at a constant pressure regardless of the pressure fluctuation of the primary pressure. Thereby, the pressure regulation accuracy of the pressure reducing valve can be improved.

  In the above invention, the insertion member includes a base rod and a rod, the base rod is fixed to the housing and passes through the drive piston, and the rod is biased by a spring member. Preferably, it is in contact with the base rod and inserted into the decompression piston.

  When the rod and the base rod are integrally formed, high processing accuracy and assembly accuracy are required to suppress contact and contact between the insertion member and the decompression piston due to axial misalignment or inclination. Compared to this, according to the above-described configuration, it is possible to suppress the piece contact without requiring high processing accuracy and assembly accuracy. Thereby, the processing cost of components can be suppressed, the sliding friction of the decompression piston can be reduced, and the responsiveness of the decompression piston can be improved.

  ADVANTAGE OF THE INVENTION According to this invention, the deformation | transformation of the pressure-reduction piston or the valve-seat part by applying excessive pressing force can be suppressed, and the pressure-reduction valve excellent in durability and reliability can be provided.

It is sectional drawing which shows the pressure reducing valve which concerns on 1st Embodiment of this invention. It is a graph which shows the relationship between the force and the secondary pressure which act on each structure of the pressure-reduction valve shown in FIG. It is a graph which shows the relationship between the displacement of each structure of the pressure-reduction valve shown in FIG. 1, and secondary pressure. It is sectional drawing which shows the pressure reducing valve which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows the pressure reducing valve which concerns on 3rd Embodiment of this invention.

  Hereinafter, the pressure reducing valves 1, 1A and 1B according to the embodiments of the present invention will be described with reference to the drawings described above. In addition, the concept of the up-and-down direction in embodiment is used for convenience of explanation, and suggests that the arrangement and direction of the configuration of the pressure reducing valves 1, 1A, 1B are limited to that direction. is not. The pressure reducing valves 1, 1 </ b> A, 1 </ b> B described below are only one embodiment of the present invention, and the present invention is not limited to the embodiment. Additions, deletions, and changes are made without departing from the spirit of the invention. Is possible.

<First Embodiment>
[Composition of pressure reducing valve]
The pressure reducing valve 1 is a valve used when the working fluid, mainly high pressure gas, is reduced to a working pressure or atmospheric pressure. A supply flow path connected to a gas supply source such as a high pressure tank, a discharge flow path connected to the atmosphere, etc. Used to intervene. The pressure reducing valve 1 includes a housing 2, a pressure reducing piston 3, a driving piston 4, a rod 5, a base rod 6, a first spring member 7, a second spring member 8, a third spring member 9, and a buffer spring 10. The

  The housing 2 includes a first housing part 11 and a second housing part 12. An insertion hole 13, a primary port 14, and a secondary port 15 are formed in the first housing part 11. The insertion hole 13 is a hole having a circular cross section that opens upward. A primary side passage 16 is formed in the bottom portion that defines the insertion hole 13, and the insertion hole 13 and the primary port 14 are connected via the primary side passage 16. In addition, a secondary side passage 17 is formed on a side surface that defines the insertion hole 13, and the insertion hole 13 and the secondary port 15 are connected via the secondary side passage 17. The primary side passage 16 and the secondary side passage 17 configured in this way constitute a valve passage 18 together with a primary side region 28 and a secondary side region 29 (both regions included in the insertion hole 13) described later, The primary port 14 and the secondary port 15 are connected via the valve passage 18. The second housing portion 12 is inserted into the insertion hole 13 from above so as to close the opening.

  The second housing part 12 has a generally cylindrical shape with a bottom, and a tip part 21 of the second housing part 12 has a small diameter with respect to the main body part 22 which is a remaining part. The second housing part 12 is attached to the first housing part 11 by screwing the distal end portion 21 into the insertion hole 13 in a state where a seal is achieved. In addition, a substantially cylindrical seal portion 23 is integrally formed on the top of the tip portion 21. The seal portion 23 is located in the main body portion 22 and is provided so as to surround the inner opening of the distal end portion 21. A guide portion 24 is formed on the inner peripheral surface of the distal end portion 21. The guide portion 24 is formed to have a smaller diameter than the other remaining portions and is positioned on the distal end side, and the decompression piston 3 is inserted therein so as to be movable in the vertical direction.

  The decompression piston 3 has a bottomed cylindrical shape, and an intermediate portion 3a thereof is inserted into the guide portion 24 so as to be movable in the vertical direction. The seat portion 3b, which is the tip portion of the decompression piston 3, has a smaller diameter than the intermediate portion 3a, protrudes downward from the guide portion 24, and faces the opening of the primary passage 16. An annular protruding piece 25 is formed around the opening of the primary passage 16 so as to surround it. On the other hand, the sheet portion 3 b has an annular sheet member 26 at a position facing the protruding piece 25. The seat member 26 is made of a material softer than the protruding piece 25 such as rubber, synthetic resin, or soft metal, and the seat member 26 is seated on the protruding piece 25 that is a valve seat (that is, the decompression piston 3 is positioned at the closed position). Thus, the valve passage 18 is closed. Further, when the decompression piston 3 moves upward and the seat member 26 is positioned at the open position where it is separated from the protruding piece 25, the valve passage 18 is opened, and an orifice 27 is formed between the seat member 26 and the protruding piece 25. . By this orifice 27, the insertion hole 13 is divided into a primary region 28 inside the orifice 27 and a secondary region 29 outside.

  Thus, the base end portion 3c of the decompression piston 3 that opens and closes the valve passage 18 has a flange portion 3d on the outer peripheral surface thereof. The flange portion 3d extends over the entire circumference in the circumferential direction of the proximal end portion 3c, protrudes in the radial direction, and projects toward the inner circumferential surface of the distal end portion 21. The flange portion 3d is positioned above the guide portion 24, and a cylindrical first spring accommodating space 30 is formed between the guide portion 24 and the flange portion 3d. The first spring member 7 is accommodated in the first spring accommodating space 30.

  The first spring member 7, which is a compression coil spring, is externally mounted on the decompression piston 3, the lower end thereof is supported by the guide portion 24, and the upper end is supported by the flange portion 3 d. The first spring member 7 arranged in this way is compressed and biases the pressure-reducing piston 3 in the direction of the open position, that is, upward to open the valve passage 18. A drive piston 4 is provided above the pressure-reducing piston 3 with an interval so that a later-described buffer spring 10 is interposed therebetween.

  The drive piston 4 is generally cylindrical and is provided in the main body portion 22 of the second housing portion 12 so as to be movable in the vertical direction. Specifically, the drive piston 4 is inserted in a state where the tip end portion (that is, the lower end portion) 31 achieves sealing in the seal portion 23 and can move in the seal portion 23 in the vertical direction. Is arranged.

  Further, a portion of the drive piston 4 on the base end portion 33 side (that is, the upper end side) from the intermediate portion 32 protrudes from the seal portion 23, and the intermediate portion 32 protrudes radially outward from the inner hole of the seal portion 23. ing. Therefore, when the drive piston 4 moves toward the decompression piston 3 (that is, downward), the intermediate portion 32 hits the upper end of the seal portion 23 so that the movement of the drive piston 4 is restricted. At this time, the length of the seal portion 23 is adjusted so that the tip of the drive piston 4 does not hit the decompression piston 3 located at the closed position. Thus, the seal portion 23 serves as a stopper for preventing the drive piston 4 from hitting the decompression piston 3.

  Further, a flange portion 34 is formed on the outer peripheral portion of the base end portion 33 of the drive piston 4 so as to extend over the entire circumferential direction. The flange portion 34 protrudes outward in the radial direction, and the outer peripheral portion reaches the inner peripheral portion of the main body portion 22. The flange portion 34 is provided with a seal member 35, and the seal member 35 seals between the inner peripheral portion of the main body portion 22 and the flange portion 34.

  Further, the second housing part 12 has an annular spring receiving part 36 at a position facing the flange part 34. The spring receiving portion 36 is located away from the flange portion 34 in the vertical direction. Therefore, a cylindrical second spring accommodating space 37 is formed between the flange portion 34 and the spring receiving portion 36, and the second spring member 8 is accommodated in the second spring accommodating space 37. . The second spring member 8, which is a compression coil spring, is externally attached to the seal portion 23 in a compressed state, and has a lower end supported by the spring receiving portion 36 and an upper end supported by the flange portion 34. Therefore, the drive piston 4 is biased upward by the second spring member 8 so as to be separated from the decompression piston 3. The base rod 6 is inserted into the inner hole of the drive piston 4 biased upward as described above from above.

  The base rod 6 has a generally cylindrical shape, and a base end portion 6 a is fixed to the ceiling portion of the second housing portion 12. Further, the base end portion 6 a of the base rod 6 serves as a stopper for the drive piston 4, so that the base end portion 33 of the drive piston 4 does not hit the ceiling portion of the second housing portion 12. The distal end side portion 6b has a small diameter with respect to the proximal end portion 6a thus configured, protrudes toward the drive piston 4, and is inserted into the proximal end portion 33 side of the inner hole of the drive piston 4. ing. The tip of the base rod 6 has a partially spherical shape, and the rod 5 is provided so as to abut on the tip surface.

  The rod 5 has a substantially cylindrical shape and is formed with a smaller diameter than the base rod 6. The rod 5 is located below the base rod 6, and the proximal end portion of the rod 5 is inserted into the distal end portion 31 of the drive piston 4. The proximal end portion of the rod 5 has a flange portion 5a. The flange portion 5a extends over the entire circumference in the circumferential direction of the base end portion and protrudes outward in the radial direction. A third spring accommodating space 38 is formed below the flange portion 5a. The third spring accommodating space 38 is substantially cylindrical so as to surround the proximal end portion of the rod 5, and the third spring member 9 is accommodated in the third spring accommodating space 38. The third spring member 9 is packaged on the base end side portion of the rod 5 and urges the flange portion 5a upward. As a result, the base end portion of the rod 5 is pressed against the tip of the base rod 6, and the rod 5 and the base rod 6 are in contact with each other.

  On the other hand, the tip end portion of the rod 5 protrudes downward from the drive piston 4 and is inserted into the decompression piston 3. A seal member 39 is provided on the inner peripheral portion of the decompression piston 3, and the gap between the rod 5 inserted by the seal member 39 and the decompression piston 3 is sealed. Further, a back pressure chamber 40 is formed between the tip of the rod 5 and the bottom surface of the pressure reducing piston 3 on the inner peripheral portion of the pressure reducing piston 3. The back pressure chamber 40 is formed in a circular cross section, and the hole diameter thereof substantially coincides with the tip diameter (that is, the orifice diameter) of the protruding piece 25. Further, a communication path 41 is formed in the seat portion 3 b of the decompression piston 3, and the back pressure chamber 40 and the primary side region 28 are connected by this communication path 41.

  The decompression piston 3 and the drive piston 4 configured as described above are separated from each other in the vertical direction, and are positioned so that the proximal end portion of the decompression piston 3 and the distal end portion of the drive piston 4 face each other. Further, concave portions 42 and 43 are formed in the base end portion of the decompression piston 3 and the distal end portion of the drive piston 4, respectively, and the concave portions 42 and 43 are positioned so as to face each other. Specifically, the recess 42 is formed in a cylindrical shape around the inner hole of the decompression piston 3, and the recess 43 is formed in a cylindrical shape around the inner hole of the drive piston 4. A cylindrical buffer spring accommodating space 44 is formed around the rod 5 by the recesses 42 and 43, and the buffer spring 10 is accommodated in the buffer spring accommodating space 44.

  The buffer spring 10 that is a pressing member is elastically deformable, and is constituted by, for example, a spring member in which a compression coil spring or a plurality of disc springs are stacked in the vertical direction. The lower end and upper end of the buffer spring 10 are supported by upper and lower surfaces of the recesses 42 and 43, that is, spring receiving seats 45 and 46, and are arranged between the pressure-reducing piston 3 and the drive piston 4. . The buffer spring 10 arranged in this way is pressed against the drive piston 4 by the pressure-reducing piston 3 biased by the first spring member 7, and transmits a downward driving force acting on the drive piston 4 to the pressure-reducing piston 3. It is like that.

  Further, the spring constant of the buffer spring 10 (corresponding to the elastic coefficient related to the expansion and contraction of the spring) is larger than the spring constant of the second spring member 8 (corresponding to the elastic coefficient related to the expansion and contraction of the spring), and the elasticity of the seat member 26 is increased. It is smaller than the coefficient (equivalent to the spring constant). That is, the buffer spring 10 has a deformation amount per unit load smaller than that of the second spring member 8 and larger than that of the seat member 26. Therefore, the buffer spring 10 is deformed by itself when the large driving force is generated in the drive piston 4 to absorb the deformation of the sheet member 26 and prevents the sheet member 26 from being deformed.

  In the pressure reducing valve 1 configured as described above, a space is formed between the base end portion 33 of the drive piston 4 and the ceiling portion of the second housing portion 12, and a space therebetween is a secondary pressure chamber 50. The secondary pressure chamber 50 is connected to the third spring accommodating space 38 by the communication hole 51 formed in the base rod 6 even when the base end portion of the drive piston 33 contacts the base rod 6. The third spring accommodating space 38 is connected to the passage 52. The passage 52 is a cylindrical flow path formed between the rod 5 and the inner peripheral portion of the front end portion of the drive piston 4, and the outer diameter of the rod 5 is slightly smaller than the inner diameter of the front end side of the drive piston 4. It is formed by making it small. The passage 52 extends from the third spring accommodating space 38 to the recess 43, and the third spring accommodating space 38 and the buffer spring accommodating space 44 are connected by the passage 52. The buffer spring accommodating space 44 is connected to the passage 53.

  The passage 53 is a cylindrical passage formed between the rod 5 and the inner peripheral portion of the decompression piston 3, and the outer diameter of the rod 5 is made slightly smaller than the inner diameter of the proximal end side of the decompression piston 3. Formed with. The passage 53 extends downward from the recess 42, a lower end portion thereof is positioned above the seal member 39, and an insertion hole 54 is connected to the lower end portion thereof. The insertion hole 54 is formed in the decompression piston 3 and extends outward in the radial direction and is connected to the first spring accommodating space 30. Further, a communication hole 55 is formed in the distal end portion 21 of the second housing portion 12, and the first spring accommodating space 30 and the secondary side region 29 are connected by the communication hole 55.

  The communication hole 55, the insertion hole 54, the passage 53, the passage 52, and the communication hole 51 formed in this way constitute a communication passage 56 together with the first spring accommodation space 30, the buffer spring accommodation space 44, and the third spring accommodation space 38. The secondary pressure chamber 50 and the secondary region 29 are connected by the communication passage 56. Thereby, the secondary pressure P2 is led to the secondary pressure chamber 50, and the drive piston 4 faces the secondary pressure chamber 50 of the base end portion 33 with the secondary pressure P2 led to the secondary pressure chamber 50. The secondary pressure receiving surface 57 receives pressure. Thereby, the drive piston 4 is pushed downward by the drive force according to the secondary pressure P2.

[Operation of pressure reducing valve]
Hereinafter, the operation of the pressure reducing valve 1 when the working fluid led to the primary port 14, for example, high pressure gas, is depressurized will be described with reference to FIGS. 1 to 3. The graph of FIG. 2 shows the relationship between the force acting on each configuration (the drive piston 4, the second spring member 8, and the buffer spring 10) and the secondary pressure P2, and the vertical axis represents each configuration. The absolute value of the acting force is shown, and the horizontal axis shows the absolute value of the secondary pressure P2. The graph of FIG. 3 shows the relationship between the displacement amount (the deformation amount with respect to the buffer spring 10) and the secondary pressure P2 of each configuration (the drive piston 4, the decompression piston 3, and the buffer spring 10). The vertical axis indicates the absolute value of the displacement amount of each component, and the horizontal axis indicates the absolute value of the secondary pressure P2.

  Since the pressure reducing piston 3 is urged in the direction of the open position by the first spring member 7 and the drive piston 4 is urged in the direction of the open position by the second spring member 8, the pressure reducing valve 1 is normally opened. It has become. When the high pressure gas is guided to the primary port 14, the high pressure gas guided to the primary port 14 is guided to the secondary region 29 through the orifice 27. At this time, the high pressure gas is reduced from the primary pressure P1 to the low secondary pressure P2, and the reduced low pressure secondary pressure P2 is supplied to the downstream equipment through the secondary passage 17 and the secondary port 15. Or discharged from the outlet.

  The decompressed low-pressure gas is guided not only to the secondary side passage 17 but also to the secondary pressure chamber 50 via the communication passage 56. Thereby, the secondary pressure P2 acts on the secondary pressure receiving surface 57 of the drive piston 4, and the drive piston 4 is pushed toward the decompression piston 3 (ie, downward) by the secondary pressure P2. When the secondary pressure P2 exceeds the minimum driving pressure p1 and the driving force by the secondary pressure P2 exceeds the urging force of the second spring member 8, the driving piston 4 moves toward the pressure reducing piston 3 and acts on the driving piston 4. The downward pressing force is transmitted to the decompression piston 3 through the buffer spring 10. Accordingly, the decompression piston 3 moves in the direction of closing the orifice 27, that is, in the direction of the closed position. Thereby, the opening degree of the valve channel | path 18 becomes small, and the secondary pressure P2 falls. The decompression piston 3 and the drive piston 4 are moved to a position where the driving force by the secondary pressure P2, the urging force by the first spring member 7 and the second spring member 8, and other forces acting on the decompression piston 3 and the drive piston 4 are balanced. Move.

  For example, when the secondary pressure P2 decreases and the driving force decreases, and the urging force of the second spring member 8 exceeds the driving force of the secondary pressure P2, the driving piston 4 moves away from the decompression piston 3 (ie, upward). ) The decompression piston 3 biased toward the drive piston 4 by the first spring member 7 (that is, upward) moves in the direction of the open position in conjunction with the drive piston 4. As a result, the orifice 27 is opened, and the secondary pressure P <b> 2 rises and is held at a set pressure corresponding to the urging force of the first spring member 7 and the second spring member 8.

  In the pressure reducing valve 1 in which the secondary pressure P2 is maintained at the set pressure in this way, an excessive surge pressure is generated in the secondary port 15 due to a failure of a downstream device or a system malfunction, and the secondary pressure P2 is reduced. May be sudden and excessively high. In the pressure reducing valve 1, when the secondary pressure P <b> 2 reaches the specified pressure p <b> 2, the pressure reducing piston 3 pushed by the drive piston 4 moves to the closed position, and the seat member 26 is seated on the protruding piece 25. When the secondary pressure P2 becomes higher than the specified pressure p2 (> p1), the buffer spring 10 starts to elastically deform. Thus, when the buffer spring 10 is elastically deformed by itself, the pressing force transmitted to the pressure-reducing piston 3 via the buffer spring 10 can be suppressed to the spring force which is a reaction force from the buffer spring 10, and the pressing force Can be suppressed to a force extremely lower than the driving force by the surge pressure. Therefore, the pressing force acting between the sheet member 26 and the protruding piece 25 can be suppressed, and deformation of the sheet member 26 can be suppressed. In other words, when the buffer spring 10 is elastically deformed by itself, the displacement of the drive piston 4 due to the pressing force of the secondary pressure P2 is absorbed by the buffer spring 10, and the amount of movement of the seating decompression piston 3 can be suppressed. . Thereby, deformation of the sheet member 26 can be suppressed.

  In particular, in the present embodiment, since the spring constant of the buffer spring 10 is smaller than the elastic coefficient of the seat member 26, the buffer spring 10 is deformed more greatly with a small force with respect to the seat member 26. . Therefore, even when the secondary pressure P2 becomes higher than the specified pressure p2, the displacement of the drive piston 4 is absorbed by the buffer spring 10, so that the amount of movement of the decompression piston 3 can be made extremely small, and the seat member 26 Deformation can be prevented.

  On the other hand, since the spring constant of the buffer spring 10 is set larger than the spring constant of the second spring member 8, in a normal state (that is, a state where an excessive secondary pressure is not acting on the secondary port 15). The buffer spring 10 is hardly elastically deformed. Therefore, the downward driving force acting on the drive piston 4 can be transmitted to the decompression piston 3 as it is, and even when the buffer spring 10 is provided, the responsiveness during pressure regulation can be maintained. Thereby, the pressure-reduction valve 1 excellent in responsiveness is realizable.

  Further, when the secondary pressure P2 is higher than the allowable drive pressure p3 (> p2), the amount of deformation of the buffer spring 10 becomes a predetermined amount, the intermediate portion 32 of the drive piston 4 hits the seal portion 23, and the lower side of the drive piston 4 Movement to is regulated. Thereby, it is possible to prevent the drive piston 4 from coming into direct contact with the decompression piston 3. When the driving piston 4 and the pressure reducing piston 3 hit without restricting the movement of the driving piston 4 in this way, the pressing force cannot be absorbed by the buffer spring 10, so that all the force acting on the driving piston 4 is reduced. Act on. Therefore, the sheet member 26 receives a large pressing force from the protruding piece 25, and the sheet member 26 is greatly deformed. When the deformation amount is increased, the sheet member 26 is plastically deformed and does not return to the original shape. However, in the pressure reducing valve 1, the movement of the driving piston 4 is restricted to prevent the driving piston 4 from coming into direct contact with the pressure reducing piston 3, thereby eliminating such a problem and preventing the deformation of the seat member 26. Moreover, the deformation amount of the buffer spring 10 can be limited by setting the movement amount restriction value of the drive piston 4 in advance. Thereby, the elastic restoring force (that is, the pressing force transmitted to the pressure-reducing piston 3) of the buffer spring 10 can be limited, and the deformation of the sheet member 26 can be prevented.

  In addition, when only the stopper by the seal part 23 is provided without providing the buffer spring 10, the position of the drive piston 4 when the decompression piston 3 is seated and the position where the drive piston 4 is regulated are balanced. It is difficult. This is because, for example, if the distance between the two positions is large, the amount of deformation of the seat member 26 increases, and if the distance between the two positions is shortened, the processing accuracy is increased in order to seat the decompression piston 3 properly on the protruding piece 25. This is because it needs to be increased. Therefore, by providing the seal portion 23 while providing the buffer spring 10, the function as described above can be achieved for the first time.

  In the pressure reducing valve 1, a back pressure chamber 40 is formed in the pressure reducing piston 3 by inserting the rod 5 into the pressure reducing piston 3. The primary pressure P1 is guided from the primary side region 28 to the back pressure chamber 40 via the communication path 41, and the primary pressure P1 of the primary side region 28 received by the decompression piston 3 is canceled by the primary pressure P1. It is like that. Therefore, the influence of the pressure fluctuation of the primary pressure P1 on the regulation of the secondary pressure P2 can be substantially eliminated, and the secondary pressure P2 can be regulated almost accurately to a constant pressure regardless of the pressure fluctuation of the primary pressure P1. it can. Thereby, the pressure regulation accuracy of the pressure reducing valve 1 can be improved.

  When the rod 5 and the base rod 6 are integrally formed, high processing accuracy and assembly are performed in order to suppress contact with the rod 5 and the base rod 6 due to the axial displacement and inclination of the decompression piston 3 and contact with each other. Accuracy is required. Compared with this, by making the rod 5 and the base rod 6 separate, it is possible to suppress the one-piece contact without requiring high processing accuracy and assembly accuracy. Thereby, the processing cost of components can be suppressed, the sliding friction of the decompression piston 3 can be reduced, and the responsiveness of the decompression piston 3 can be improved.

Second Embodiment
The pressure reducing valve 1A according to the second embodiment of the present invention is similar in configuration to the pressure reducing valve 1 according to the first embodiment. Therefore, only the configuration different from the configuration of the pressure reducing valve 1 according to the first embodiment will be described for the configuration of the pressure reducing valve 1A according to the second embodiment, and the description of the same configuration will be omitted. The same applies to a pressure reducing valve 1B according to a third embodiment to be described later.

  As shown in FIG. 4, in the pressure reducing valve 1A, an annular seat member 26A is formed around the opening of the primary passage 16 so as to surround the opening, and a seat portion 3b which is a tip portion of the pressure reducing piston 3A. Has a protruding piece 25A at a position facing the sheet member 26A. When the protruding piece 25A is seated on the seat member 26A which is a valve seat, the valve passage 18 is closed.

  The pressure reducing valve 1 </ b> A includes a buffer member 10 </ b> A instead of the buffer spring 10. The shock-absorbing member 10 </ b> A, which is a pressing member, is a cylindrical member made of an elastically deformable member such as rubber or synthetic resin, and is provided between the recesses 42 and 43 while being externally mounted on the rod 5. The buffer member 10 </ b> A has an elastic coefficient smaller than that of the seat member 26 </ b> A and has an elastic coefficient larger than the spring constant of the second spring member 8.

  The pressure reducing valve 1A according to the second embodiment configured as described above has the same operational effects as the pressure reducing valve 1 according to the first embodiment.

<Third Embodiment>
As shown in FIG. 5, the pressure reducing valve 1 </ b> B according to the third embodiment does not include the rod 5 and the base rod 6, and the pressure reducing piston 3 </ b> B does not have the back pressure chamber 40 and the communication path 41. Moreover, the secondary side channel | path 17B connected with the secondary port 15B is formed in the ceiling part of the 2nd housing part 12, and the primary side channel | path 16 and the secondary side channel | path 17B are formed coaxially.
Since the pressure reducing valve 1B according to the third embodiment does not include the back pressure chamber 40, the primary pressure P1 guided to the primary side region 28 cannot be canceled out and is easily affected. The same effects as the pressure reducing valve 1 of the first embodiment are obtained.

<Other embodiments>
In the pressure reducing valves 1, 1 </ b> A, 1 </ b> B of the first to third embodiments, the buffer spring 10 or the buffer member 10 </ b> A, which is a pressing member, is built in the distal end portion 31 of the drive piston 4. May be disposed between the drive piston 4 and the decompression piston 3. Even in this case, the same effect as the pressure reducing valve 1 of the first embodiment can be obtained. Note that the fact that the pressing member is disposed between the drive piston 4 and the pressure-reducing piston 3 is not limited to being sandwiched between the drive piston 4 and the pressure-reducing piston 3, and at least a part of the pressing member is driven. What is necessary is just to interpose between piston 4 and pressure reduction piston 3 so that it may space apart.

  In the first and second embodiments, similarly to the third embodiment, the primary side passage 16 and the secondary side passage 17 may be formed on the same axis. In the first and third embodiments, the second embodiment Similarly to the embodiment, the buffer spring 10 may be replaced with a buffer member 10A made of rubber or synthetic resin, or the positional relationship between the sheet member 26 and the protruding piece 25 may be interchanged. The reverse is also true.

1, 1A, 1B Pressure reducing valve 2 Housing 3, 3A, 3B Pressure reducing piston 4 Drive piston 5 Rod 6 Base rod 8 Second spring member 10 Buffer spring 10A Buffer member 14 Primary port 15 Secondary port 18 Valve passage 23 Seal portion 25, 25A Protrusion piece 26, 26A Sheet member 40 Back pressure chamber 41 Communication path 57 Secondary pressure receiving surface

Claims (6)

A housing having a valve passage connected to the primary port and the secondary port, and a valve seat;
A pressure reducing piston that is provided in the housing and moves between a closed position that sits on the valve seat and closes the valve passage and an open position that opens the valve passage, and adjusts the opening of the valve passage;
A drive piston which is movably provided in the housing and is provided away from the decompression piston, and receives a secondary pressure in a direction toward the decompression piston;
A biasing member that imparts a biasing force against the secondary pressure to the drive piston;
The driving force generated by the secondary pressure acting on the driving piston is disposed between the pressure reducing piston and the driving piston and is transmitted to the pressure reducing piston to push the pressure reducing piston from the open position toward the closed position. And a pressing member that elastically deforms so as to absorb the driving force generated by the secondary pressure .   The pressure reducing valve according to claim 1, wherein the pressing member has an elastic coefficient larger than an elastic coefficient of the biasing member. One of the decompression piston and the valve seat has an annular protrusion.
The other of the pressure reducing piston and the valve seat has a seat member that abuts against the protruding piece and closes the valve passage when the pressure reducing piston moves to the closed position,
The pressure reducing valve according to claim 1, wherein the pressing member has an elastic coefficient smaller than an elastic coefficient of the sheet member. The housing has a stopper for restricting movement of the drive piston in a direction toward the decompression piston,
The stopper is adapted to stop the movement of the drive piston so that the drive piston does not come into contact with the pressure-reducing piston while allowing the deformation of the pressing member when the pressure-reducing piston is located at the closed position. The pressure reducing valve according to any one of claims 1 to 3. The housing is provided with an insertion member that penetrates the drive piston and is inserted into the decompression piston,
The valve passage is partitioned into a primary pressure chamber connected to the primary port by the decompression piston and a secondary pressure chamber connected to the secondary port,
The decompression piston has a back pressure chamber closed by the insertion member, and a communication path connecting the back pressure chamber and the primary pressure chamber,
The said back pressure chamber is formed so that the primary pressure led there may act in the direction which opposes the primary pressure of the said primary side pressure chamber with respect to the said pressure reduction piston. The pressure reducing valve according to one. The insertion member has a base rod and a rod,
The base rod is fixed to the housing and passes through the drive piston,
The pressure reducing valve according to claim 5, wherein the rod is urged by a spring member to abut against the base rod and is inserted into the pressure reducing piston.

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