JP3714726B2 - Pilot operated check valve - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pilot operated check valve in which a poppet valve body is separated from a valve seat by a pilot piston.
[0002]
[Prior art]
Conventionally, as this kind of pilot check valve, the opening of the throttle is adjusted by moving the adjustment cylinder in the axial direction to give a throttle action to the fluid flowing in the control flow, and the poppet valve is throttled in the free flow. It is known that a large amount of seating can be taken without being restricted by adjusting the opening degree of the section and a large flow rate can be circulated. (For example, see Japanese Patent Publication No. 6-43873.)
[0003]
[Problems to be solved by the invention]
However, in such a conventional pilot operated check valve, if it is desired to provide a throttle action during free flow, a throttle valve must be provided in series with this pilot operated check valve, and the valve function can be changed. As a result, the number of valves increased and the cost increased.
[0004]
According to the present invention, the poppet valve body is housed inside and the valve function is changed by exchanging the cylinder body which is detachably attached to the valve body, and the increase in the number of valve points accompanying the change in the valve function is suppressed and the cost is reduced. An object of the present invention is to provide a pilot-operated check valve that can be reduced.
[0005]
[Means for Solving the Problems]
In the pilot operated check valve according to the present invention, the fluid supply / discharge flow path and the load flow path connected to the fluid actuator are provided in the valve body so as to open with a gap in the axial direction to a receiving hole formed in the valve body. The receiving hole is opened on the side of the valve body, and a cylinder with a poppet valve element inside is inserted into the receiving hole from the opening on the side, and is detachably attached to the valve body. The opening on the side of the valve body is closed to prevent fluid leakage, and the cylinder is connected to the large-diameter hole into which the poppet valve body is slidably inserted, and to the large-diameter hole in the axial direction. A small-diameter hole opened at the tip to be inserted into the receiving hole of the cylindrical body, and a valve seat on which the poppet valve body is seated is formed at the connecting step portion of the large-diameter hole and the small-diameter hole, and the cylindrical body The large-diameter hole and the load flow path that opens to the collection hole are connected, and the small-diameter hole of the cylindrical body and the supply / discharge flow path that opens to the collection hole are connected to each other. The load passages are provided in communication with each other via a valve seat inside the cylinder, and the pilot piston is slidably inserted into the receiving hole so as to face the tip where the small-diameter hole of the cylinder opens. A piston portion that contacts the tip of the body, and a rod portion that extends in the axial direction to the piston portion and passes through the small diameter hole of the cylindrical body and contacts the poppet valve body head. The rod part presses the poppet valve body detachably from the valve seat by the action of pilot pressure during the control flow in which the fluid flows through the supply / exhaust flow path. The poppet valve body is provided with a predetermined amount by contact with the head of fluid pressure that flows through the small diameter hole from the supply / discharge flow path when the fluid flows freely from the supply / discharge flow path to the load flow path through the valve seat It is provided so that it can be detached from the valve seat larger than the predetermined amount during control flow. The connection between the large-diameter hole of the cylindrical body and the load flow path opening in the housing hole is provided in parallel by the throttle hole and the throttling release hole in the cylindrical body with a gap in the axial direction. A hole is provided to allow fluid to flow both when the poppet valve body is released during control flow and when the poppet valve body is released during free flow, and a throttling release hole is used when a predetermined amount of poppet valve body is released during control flow. The cylinder is closed by the poppet valve body and fluid is circulated by the removal of the poppet valve body during free flow, and the cylinder having the throttle hole and the throttle release hole can be interchanged with the cylinder having the throttle hole. It is characterized by providing. In this case, a filter member that filters the fluid may be wound around the outer peripheral surface of the cylindrical body that is inserted into the receiving hole and detachably attached to the valve body.
[0006]
In such a configuration of the present invention, when a cylinder having a throttle hole and a throttle release hole is attached to the valve body, the poppet valve body is operated during a control flow in which fluid flows from the load channel to the supply / discharge channel via the valve seat. The throttle release hole is closed without detaching only a predetermined amount from the valve seat, and the fluid in the load flow path is controlled by the throttle hole and flows to the supply / discharge flow path through the valve seat. In addition, when the fluid flows freely from the supply / discharge flow path to the load flow path through the valve seat, the poppet valve body disengages from the valve seat larger than the predetermined amount during the control flow and releases the blockage of the throttle release hole. The fluid in the supply / discharge flow path flows into the load flow path through the valve seat at a large flow rate that flows through the throttle release hole and the throttle hole. Next, when the cylinder body having the throttle hole and the throttle release hole is replaced and the cylinder body having the throttle hole is attached to the valve body, the poppet valve body is released from the valve seat by a predetermined amount and free during control flow. Regardless of the large separation of the poppet valve body from the valve seat during the flow, the fluid flows through the throttle hole, and the fluid is throttled and controlled during both the control flow and the free flow. For this reason, it is possible to provide a throttling action during free flow by exchanging the cylinders, and to suppress an increase in the number of valve points accompanying a change in the valve function, thereby reducing costs.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 2, reference numeral 1 denotes a rectangular parallelepiped valve body having a gap in the axial direction to a receiving hole 2 formed with fluid supply / discharge passages A1 and B1 and load passages A and B inside. And open. As shown in FIG. 2, the load flow path A is connected to the rod side chamber 3A of the fluid cylinder 3 as a fluid actuator, the load flow path B is connected to the head side chamber 3B of the fluid cylinder 3, and the fluid cylinder 3 carries the load W. It hangs up and down freely. The supply / discharge flow paths A1 and B1 are each connected to a three-position / four-port electromagnetic switching valve 4. The electromagnetic switching valve 4 shuts off both the supply / discharge flow paths A1, B1 in the neutral position and supplies / discharges current by de-energization. The paths A1 and B1 are provided to be able to switch and communicate with the pressure source P and the tank T.
[0008]
The receiving hole 2 formed in the valve body 1 has one end opened on the side surface 1A of the valve body 1 and the other end opened on the side surface 1B of the valve body 1, and is provided from both sides of the small-diameter portion 2A in the center in the axial direction. Formed in a stepped shape with the medium diameter portions 2B, 2C and the large diameter portions 2D, 2E connected to the outer side in the axial direction, the inner diameter surfaces of the large diameter portions 2D, 2E opening to the side surfaces 1A, 1B. Screws are engraved. 4A is a cylinder inserted into the receiving hole 2 from the opening of the side surface 1A, and the poppet valve element 6A is accommodated therein, and its distal end reaches the small diameter portion 2A of the receiving hole 2 and its outer end. Has an engaging portion 5A for engaging a tool (not shown), and is removably attached to the valve body 1 by being screwed into the large diameter portion 2D by rotation of the tool engaged with the engaging portion 5A. By opening 4A, the opening of the side surface 1A is closed to prevent fluid leakage. The cylindrical body 4A has a large-diameter hole 7A and a small-diameter hole 8A that are slidably fitted in the poppet valve body 6A and penetrates in the axial direction. The large-diameter hole 7A opens to the outside. At the same time, the small-diameter hole 8 </ b> A is opened at the tip to be inserted into the collection hole 2. The external opening of the large-diameter hole 7A is provided by blocking the fluid leakage by the plug member 9A.
[0009]
Reference numeral 10A denotes a valve seat on which the poppet valve body 6A is seated, which is provided at a stepped portion of the large diameter hole 7A and the small diameter hole 8A of the cylindrical body 4A. Reference numeral 11A denotes a throttle hole, which penetrates the cylindrical body 4A in the radial direction on the outer side in the axial direction from the valve seat 10A formation position, and opens the load channel A and the cylindrical body 4A to the middle diameter portion 2B of the collection hole 2 The large diameter hole 7A is connected. Reference numeral 12A denotes a throttling cancellation hole, which penetrates the cylindrical body 4A in the radial direction with a gap in the axial direction with the throttling hole 11A, and connects the load flow path A and the large diameter hole 7A. The load channel A and the large-diameter hole 7A are connected in parallel by a throttle hole 11A and a throttle release hole 12A. 13A is a connection hole, which penetrates the cylindrical body 4A in the radial direction on the tip end side in the axial direction from the valve seat 10A formation position, and opens to the small diameter portion 2A of the collection hole 2 and the cylindrical body 4A. The small diameter hole 8A is connected. As a result, the supply / discharge flow path A1 and the load flow path A communicate with each other via the valve seat 10A. A filter member 17A is wound around the outer peripheral surface of the cylinder 4A, and covers the openings of the throttle hole 11A and the aperture release hole 12A to the outer peripheral surface of the cylinder 4A, and is accommodated in the medium diameter portion 2B of the collection hole 2. The fluid flowing through the restricting hole 11A and the restricting release hole 12A is filtered and provided. The filter member 17A is provided in contact with the connecting step portion of the small-diameter portion 2A and the medium-diameter portion 2B of the receiving hole 2 and positioned in the axial direction.
[0010]
A pilot piston 14 is slidably fitted into the small diameter portion 2A of the receiving hole 2 so as to face the tip of the small diameter hole 8A of the cylindrical body 4A, and the receiving hole 2 is inserted into the receiving hole 2 by insertion. The small diameter portion 2A has a piston portion 14A that is in contact with the tip of the cylinder 4A by blocking the gap between the supply / discharge flow passage A1 and the supply / discharge flow passage B1 that are opened with a gap in the axial direction. A rod portion 15A that is continuously provided in the direction and passes loosely through the small-diameter hole 8A of the cylindrical body 4A and comes into contact with the head of the poppet valve body 6A; and the rod portion 15B that opposes the rod portion 15A in the axial direction. Have. In the pilot piston 14, the rod portion 15A presses the poppet valve body 6A removably from the valve seat 10A by the action of the pilot pressure during the control flow in which the fluid flows from the load passage A to the supply / discharge passage A1 through the valve seat 10A. The detachment from the valve seat 10A is set to a predetermined amount by contacting the piston portion 14A with the tip of the cylindrical body 4A.
[0011]
A spring 16A is housed on the back of the poppet valve body 6A of the large-diameter hole 7A, and the poppet valve body 6A is urged in the seating direction on the valve seat 10A by the force of the spring 16A. The poppet valve body 6A is controlled by the action of the fluid pressure flowing from the supply / discharge flow path A1 through the small diameter hole 8A to the head during free flow of fluid flowing from the supply / discharge flow path A1 through the valve seat 10A to the load flow path A. The valve seat 10 </ b> A is detachably provided so that the back part is in contact with the plug member 9 </ b> A larger than the predetermined amount of detachment at the time. The throttle hole 11A is provided to circulate the fluid both when the poppet valve body 6A is detached by a predetermined amount during the control flow and when the poppet valve body 6A is in a large separation where the back portion of the poppet valve body 6A is in contact with the plug member 4A during the free flow. The throttling release hole 12A is blocked by the outer peripheral surface of the poppet valve body 6A when the poppet valve body 6A is disengaged by a predetermined amount at the time of control flow, and at the large disengagement when the back portion of the poppet valve body 6A is in contact with the plug member 9A at the time of free flow The blockage by the outer peripheral surface of the poppet valve body 6A is released and the fluid is circulated.
[0012]
4B is a cylinder inserted into the receiving hole 2 from the opening of the side surface 1B of the valve body 1, and has an engaging portion 5B for receiving the poppet valve body 6B and engaging the tool. The opening of the side surface 1B is provided so as to be detachable and closed to prevent fluid leakage. A valve seat 10B is formed in a stepped portion between the large-diameter hole 7B and the small-diameter hole 8B of the cylindrical body 4B, and the poppet valve body 6B is urged in the seating direction to the valve seat 10B by the force of the spring 16B. A throttle hole 11B is provided in a radial direction on the outer side in the axial direction from the position where the valve seat 10B is formed, and the throttle hole 11B includes a load channel B and a large-diameter hole 7B that open to the middle-diameter portion 2C of the housing hole 2. Is connected. Further, a connecting hole 13B is provided in a radial direction on the distal end side in the axial direction from the position where the valve seat 10B is formed, and the connecting hole 13B is a supply / exhaust flow path B1 and a small diameter hole 8B that open to the small diameter portion 2A of the housing hole 2. And connected. As a result, the supply / discharge flow path B1 and the load flow path B communicate with each other via the valve seat 10B.
[0013]
The rod portion 15B of the pilot piston 14 is loosely fitted in the small-diameter hole 8B of the cylindrical body 4B and is provided in contact with the head of the poppet valve body 6B. The supply / discharge passage from the load passage B through the valve seat 10B is provided. The poppet valve body 6B is provided so as to be detachable from the valve seat 10B by the action of the pilot pressure during the control flow in which the fluid flows to B1. Then, the poppet valve body 6B is detached from the valve seat 10B by setting a predetermined amount by contacting the piston portion 14A of the pilot piston 14 with the tip of the cylindrical body 4B. The poppet valve body 6B has a back that is larger than a predetermined amount of detachment at the time of control flow due to the action of the fluid pressure on the head during free flow when the fluid flows from the supply / discharge channel B1 to the load channel B via the valve seat 10B. It is provided so as to be detachable from the valve seat 10B so as to contact the member 9B. The throttle hole 11B is provided to circulate fluid both in a predetermined amount of separation of the poppet valve body 6B during the control flow and in a large separation where the back portion of the poppet valve body 6B contacts the plug member 9B during the free flow. A filter member 17B is wound around the outer peripheral surface of the cylindrical body 4B, and the filter member 17B is provided so as to cover the opening of the throttle hole 11B to the outer peripheral surface of the cylindrical body 4B in the middle diameter portion 2C of the receiving hole 2. The fluid flowing through the throttle hole 11B is filtered and provided. The filter member 17B is provided in contact with the connecting step portion of the small-diameter portion 2A and the medium-diameter portion 2C of the receiving hole 2 and positioned in the axial direction.
[0014]
Next, the operation of this configuration will be described.
1 and 2, the electromagnetic switching valve 4 is located at the neutral position, shuts off both the supply / discharge flow paths A1, B1, and the fluid cylinder 3 stops with the work W held at the rising end. The fluid pressure in the rod side chamber 3A of the fluid cylinder 3 due to the load of W acts on the back part of the poppet valve body 6A via the load flow path A and the throttle hole 11A, and the poppet valve body 6A acts on the fluid pressure and spring acting on the back part. It is pressed by the force of 16A and is seated on the valve seat 10A to block between the supply / discharge flow path A1 and the load flow path A. Further, the poppet valve body 6B is pressed by the force of the spring 16B and is seated on the valve seat 10B, thereby blocking between the supply / discharge flow path B1 and the load flow path B.
[0015]
1 and 2, when the electromagnetic switching valve 4 is energized to switch the supply / discharge flow path B1 to the pressure source P, and the supply / discharge flow path A1 is switched to the tank T, the fluid of the pressure source P Flows in the small-diameter portion 2A of the collection hole 2 through the supply / discharge flow path B1, flows through the connection hole 13B and the small-diameter hole 8B of the cylinder 4B, acts on the head of the poppet valve body 6B, and a part thereof As shown in FIG. 3, the poppet valve body 6B slides in the right direction against the force of the spring 16B by the fluid pressure acting on the head and separates from the valve seat 10B. The back part contacts the plug member 9B and communicates between the supply / discharge flow path B1 and the load flow path B via the throttle hole 11B and the filter member 17B. Further, the pilot piston 14 slides to the left by the action of the pilot pressure, and the rod portion 15A presses against the fluid pressure acting on the back portion of the poppet valve body 6A and the force of the spring 16A to detach from the valve seat 10A. The release from the valve seat 10A is set such that the piston portion 14A of the pilot piston 14 is in contact with the tip of the cylindrical body 4A, and the gap between the supply / discharge flow path A1 and the load flow path A is set via the throttle hole 11A and the filter member 17A. Communicate. At this time, the aperture release hole 12A is closed by the outer peripheral surface of the poppet valve body 6A.
[0016]
The fluid flowing through the supply / discharge passage B1 and flowing into the small-diameter portion 2A of the housing hole 2 is controlled by the throttle hole 11B through the valve seat 10B and the large-diameter hole 7B, and filtered by the filter member 17B. The fluid that flows and flows into the head side chamber 3B of the fluid cylinder 3 and flows out from the rod side chamber 3A into the load flow path A is filtered by the filter member 17A and controlled by the throttle hole 11A to be controlled by the large diameter hole 7A, the valve seat 10A, and the small diameter hole. 8A, the connection hole 13A, and the small diameter portion 2A of the collection hole 2 are discharged from the supply / discharge passage A1 to the tank T, and the fluid cylinder 3 works by meter-in control by the throttle hole 11B and meter-out control by the throttle hole 11A. W is moved downwardly in FIG.
[0017]
When the work W is lowered to the lower end, the electromagnetic switching valve 4 is de-energized to return to the neutral position in FIG. 1 and both the supply / discharge passages A1 and B1 are shut off, the poppet valve element 6A acts on the back. 1 is slid rightward by the fluid pressure and the force of the spring 16A, and is seated on the valve seat 10A as shown in FIG. 1, and the supply / discharge passage A1 and the load passage A are blocked. Further, the poppet valve body 6B slides to the left by the force of the spring 16B and is seated on the valve seat 10B as shown in FIG. 1 so as to block between the supply / discharge flow path B1 and the load flow path B. The fluid cylinder 3 holds the work W at the lower end and stops.
[0018]
When the workpiece W is held at the lower end, the electromagnetic switching valve 4 is energized to switch the supply / discharge flow path A1 to the pressure source P and the supply / discharge flow path B1 to the tank T for switching. The fluid P flows through the supply / discharge channel A1 and flows into the small diameter portion 2A of the housing hole 2, flows through the connection hole 13A and the small diameter hole 8A of the cylinder 4A, acts on the head of the poppet valve body 6A, and A part acts on the pilot piston 14 as a pilot pressure. As shown in FIG. 4, the poppet valve body 6A slides to the left against the fluid pressure acting on the back and the spring 16A force due to the fluid pressure acting on the head. It moves away from the valve seat 10A and the back part comes into contact with the plug member 9A, and the supply / discharge flow path A1 and the load flow path A are communicated in parallel via the throttle hole 11A and the throttle release hole 12A. Further, the pilot piston 14 slides rightward by the action of the pilot pressure, and the rod portion 15B presses the poppet valve body 6B against the force of the spring 16B to disengage from the valve seat 10B. The detachment is set with the piston portion 14A of the pilot piston 14 in contact with the tip of the cylinder 4B, and the supply / exhaust flow path B1 and the load flow path B communicate with each other through the throttle hole 11B.
[0019]
The fluid flowing through the supply / discharge flow path A1 and flowing into the small-diameter portion 2A of the collection hole 2 has a large flow rate flowing through the restriction release hole 12A and the restriction hole 11A via the valve seat 10A and the large-diameter hole 7A. The filtered fluid flows through the load channel A, flows into the rod side chamber 3A of the fluid cylinder 3, and flows out from the head side chamber 3B into the load channel B. The fluid is filtered by the filter member 17B, throttled by the throttle hole 11B, and controlled to a large diameter hole. 7B, the valve seat 10B, the small diameter hole 8B, the connection hole 13B, and the small diameter portion 2A of the collection hole 2 to be discharged from the supply / discharge channel B1 to the tank T, and the fluid cylinder 3 is controlled by meter-out control by the throttle hole 11B. W is moved upward in FIG.
[0020]
Then, when the workpiece W is raised to the rising end, the electromagnetic switching valve 4 is de-energized to return to the neutral position in FIG. 1 and both the supply / discharge passages A1 and B1 are shut off, the poppet valve element 6A acts on the back. 1 is slid rightward by the fluid pressure and the force of the spring 16A, and is seated on the valve seat 10A as shown in FIG. 1, and the supply / discharge passage A1 and the load passage A are blocked. Further, the poppet valve body 6B slides to the left by the force of the spring 16B and is seated on the valve seat 10B as shown in FIG. 1 so as to block between the supply / discharge flow path B1 and the load flow path B. The fluid cylinder 3 holds the workpiece W at the rising end and stops.
[0021]
With this operation, when the cylinder 4A having the throttle hole 11A and the throttle release hole 12A is exchanged and the same cylinder 4B having the throttle hole 11B is attached to the valve body 1, supply / discharge from the load channel A A poppet valve body 6B valve in a free flow in which a predetermined amount of detachment from the valve seat 10A of the poppet valve body 6A and a flow of fluid from the supply / discharge flow path A1 to the load flow path A occurs during a control flow in which fluid flows into the flow path A1. Regardless of the large separation from the seat 10B, the fluid flows through the throttle hole 11B, and the throttle control of the fluid is performed both during the control flow and during the free flow. The increase in the number of valves associated with the function change can be suppressed, and the cost can be reduced.
[0022]
Further, since the filter members 17A and 17B for filtering the fluid are wound around the outer peripheral surfaces of the cylinders 4A and 4B, the filter members 17A and 17B are attached to the valve body 1 with the attachment of the cylinders 4A and 4B. The fluid that can be attached to the main body 1 and flows through the throttle holes 11A and 11B and the throttle release hole 12A can be filtered, and the attachment of the filter members 17A and 17B to the valve main body 1 can be simplified. Further, the cylindrical body 4A and the cylindrical body 4B to be replaced with the cylindrical body 4B may be different in configuration as to whether or not the aperture eliminating hole 12A is provided, and can be shared.
[0023]
In the embodiment of the present invention, the cylinder body 4A and the cylinder body 4B are attached to the valve body 1, but it is needless to say that one cylinder body 4A or 4B may be attached if necessary. . In this case, the opening of the receiving hole 2 to which the cylinder 4B or 4A is not attached may be closed so as to prevent fluid leakage, and the blocking member and the pilot piston 14 may be provided in contact with each other.
[0024]
【The invention's effect】
Thus, according to the present invention, the cylindrical body having the throttle hole and the throttle cancellation hole is provided so as to be interchangeable with the cylindrical body having the throttle hole. The increase in the number of valve points accompanying the change in valve function can be suppressed, and the cost can be reduced. Further, the cylinders provided to be exchangeable with each other may be different in configuration whether or not they have a throttling hole, and can be shared.
[0025]
Further, by adopting a structure in which a filter member for filtering a fluid is wound around the outer peripheral surface of the cylinder, the filter member can be attached to the valve body along with the attachment of the cylinder to the valve body. Installation to the main body can be simplified.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a pilot operated check valve showing an embodiment of the present invention.
FIG. 2 is a fluid circuit diagram using the pilot operated check valve of FIG. 1;
3 is a longitudinal sectional view showing an operating state of the pilot operated check valve of FIG. 1. FIG.
4 is a longitudinal sectional view showing an operating state different from FIG. 3; FIG.
[Explanation of symbols]
1 valve body 1A, 1B side surface 2 collection hole 3 fluid cylinder (fluid actuator)
6A, 6B poppet valve body 7A, 7B large diameter hole 8A, 8B small diameter hole 10A, 10B valve seat 11A, 11B throttle hole 12A throttle release hole 14 pilot piston 14A piston part 15A, 15B rod part A, B load flow path A1, B1 supply / discharge flow path

Claims (2)

A fluid supply / discharge flow path and a load flow path connected to the fluid actuator are provided with an opening in the axial direction to an accommodation hole drilled in the valve body, and the accommodation hole opens on a side surface of the valve body. Insert the cylinder with the poppet valve body inside the opening from the side, and insert it into the receiving hole to detachably attach it to the valve body. The cylinder is provided with a large-diameter hole into which the poppet valve body is slidably fitted, and the large-diameter hole is axially connected to the large-diameter hole and inserted into the receiving hole of the cylinder. It has a small-diameter hole that opens at the tip, and a valve seat on which the poppet valve body sits is formed at the stepped portion between the large-diameter hole and the small-diameter hole, and is opened in the large-diameter hole and the collection hole of the cylindrical body And connecting the small diameter hole of the cylinder and the supply / discharge flow path opening to the collection hole, and the gap between the supply / discharge flow path and the load flow path is connected via a valve seat inside the cylinder. The pilot piston is slidably inserted into the receiving hole so as to face the tip where the small-diameter hole of the cylinder opens, and the pilot piston is in contact with the tip of the cylinder and the piston in the axial direction. A pilot pressure is provided during control flow in which fluid flows from the load flow path to the supply / discharge flow path through the valve seat, having a rod section that is continuously provided and passes through the small diameter hole of the cylindrical body and abuts against the poppet valve body head The rod part is provided so that the poppet valve body is detachably pressed from the valve seat by the action of the above, and the detachment from the valve seat is provided by setting a predetermined amount by contacting the end of the cylinder of the piston part. Is larger than a predetermined amount of detachment during control flow due to the action of the fluid pressure flowing from the supply / discharge flow path through the small diameter hole to the head during free flow of fluid flowing from the supply / discharge flow path through the valve seat to the load flow path. A load that can be detached from the seat and opens to the large-diameter hole and the collection hole of the cylinder. Connection with the passage is provided in parallel by a throttle hole and a throttling release hole with a gap in the axial direction in the cylinder body, and the throttling hole is separated by a predetermined amount of the poppet valve body during control flow. When the poppet valve body is released during free flow, the fluid is circulated and the throttling release hole is closed by the poppet valve body when the poppet valve body is released by a predetermined amount during the control flow, and the poppet valve body during free flow. A pilot-operated check valve characterized in that a cylinder having the throttle hole and the throttle release hole is provided to be exchangeable with the cylinder having the throttle hole. The pilot operated check valve according to claim 1, wherein a filter member for filtering fluid is wound around an outer peripheral surface of a cylindrical body that is inserted into the receiving hole and is detachably attached to the valve body.

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