JPH09317915A - Pilot operated check valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To contrive to change the valve function by exchanging a tube body, which has a poppet valve body built therein and made freely detachable to a valve body, and to reduce cost by restraining increase of the number of valve parts accompanying with the change of the valve function. SOLUTION: A tube body 4A including a restriction 11A and a restriction release 12A is provided exchangeable with a tube body 4B including a restriction 11B. Thus wire drawing can be given when fluid freely flows from a supply/ delivery passage A1 to a load passage A and cost can be reduced by being able to restrain increase of the number of valve part accompanying the change of valve function.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pilot operated check valve for separating a poppet valve body from a valve seat by a pilot piston.

[0002]

2. Description of the Related Art Conventionally, as a pilot operated check valve of this kind, an opening of a throttle portion is adjusted by axial movement of an adjusting cylinder to exert a throttle action on a circulating fluid at a control flow and at the time of a free flow. It is known that the poppet valve body can take a large amount of seating without being restricted by the adjustment of the opening degree of the throttle portion and can be provided with a large flow rate. (For example, see Japanese Patent Publication No. 6-43873.)

[0003]

However, in such a conventional pilot operated check valve, when it is desired to apply a throttle action during free flow, the throttle valve must be arranged in series with the pilot operated check valve. However, the number of valve points has increased in response to the change in valve function, resulting in an increase in cost.

According to the present invention, the valve function is changed by exchanging the cylinder body in which the poppet valve body is housed inside and detachably attached to the valve body, and the increase in the number of valve points due to the change in the valve function is suppressed. It is an object of the present invention to provide a pilot operated check valve for cost reduction.

[0005]

In a pilot operated check valve according to the present invention, a fluid supply / discharge passage and a load passage connected to a fluid actuator are axially separated into a storage hole formed in a valve body. And the storage hole is opened on the side surface of the valve body, and the cylinder body containing the poppet valve body inside is inserted into the storage hole from the opening on this side surface to the valve body. It is detachably attached, and the opening of the side surface of the valve body is closed by mounting the cylinder so as to prevent fluid leakage, and the cylinder has a large diameter hole for slidably inserting the poppet valve inside and this large A valve having a small diameter hole that is axially connected to the diameter hole and is opened at the tip that is inserted into the housing hole of the cylindrical body, and the poppet valve element is seated on the connecting step portion of the large diameter hole and the small diameter hole. A seat is formed to connect the large-diameter hole of the cylindrical body to the load flow path opening to the storage hole, and open to the small-diameter hole of the cylindrical body and the storage hole. The exhaust passage is connected, and the supply / exhaust passage and the load passage are communicated with each other through the valve seat inside the cylinder, and pilots to the storage hole facing the tip of the small-diameter hole of the cylinder. The piston is slidably inserted, and the pilot piston is a rod that comes into contact with the tip of the cylinder and the piston that is axially connected to the piston and that passes through the small diameter hole of the cylinder and comes into contact with the poppet valve head. And a rod portion presses the poppet valve element detachably from the valve seat by the action of pilot pressure during a control flow in which the fluid flows from the load passage to the supply / discharge passage through the valve seat. Disengagement from the valve seat is set by setting a predetermined amount by abutting the tip of the cylinder of the piston part, and the poppet valve body is supplied when the fluid flows freely from the supply / exhaust flow path to the load flow path via the valve seat. Due to the action of the fluid pressure flowing from the discharge flow path through the small diameter hole on the head, a predetermined amount of separation occurs during controlled flow. It is provided so that it can be removed from the valve seat, and the connection between the large-diameter hole of the cylinder and the load flow path that opens into the storage hole has a gap in the cylinder in the axial direction. The throttle hole is provided in parallel with the hole, the throttle hole is provided for circulating a fluid both when the poppet valve element is separated by a predetermined amount during control flow and when the poppet valve element is separated during free flow, and the throttle release hole is provided during control flow. When the poppet valve element is separated by a predetermined amount, the poppet valve element is closed and a fluid is provided to allow the fluid to flow when the poppet valve element is separated during free flow. It is characterized in that it is provided so as to be interchangeable with the cylindrical body that it has. In this case, a filter member for filtering the fluid may be wound around the outer peripheral surface of the cylindrical body that is inserted into the storage hole and is detachably attached to the valve body.

In the structure of the present invention, when the cylindrical body having the throttle hole and the throttle release hole is attached to the valve body, the poppet is flowed during the control flow in which the fluid flows from the load passage to the supply / exhaust passage through the valve seat. The valve body closes the throttle-eliminating hole without separating from the valve seat by a predetermined amount, and the fluid in the load flow passage is throttle-controlled by the throttle hole and flows into the supply / discharge passage through the valve seat. Further, when the fluid flows from the supply / exhaust flow passage to the load flow passage through the valve seat, the poppet valve body separates from the valve seat more than a predetermined amount of separation during the control flow, and releases the blockage of the throttle relief hole. The fluid in the supply / discharge channel flows into the load channel through the valve seat at a large flow rate through the throttle relief 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 can be separated from the valve seat by a predetermined amount and freely moved during the control flow. The fluid flows through the throttle hole regardless of the large disengagement of the poppet valve body from the valve seat during flow, and the fluid is throttle-controlled both in the control flow and in the free flow. For this reason, it is possible to apply a throttling action during free flow by exchanging the cylindrical body, and it is possible to suppress an increase in the number of valve points due to a change in valve function and to reduce cost.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. In FIGS. 1 and 2, reference numeral 1 denotes a rectangular parallelepiped-shaped valve main body having an axial gap to a storage hole 2 which is provided with fluid supply / discharge channels A1 and B1 and load channels A and B therein. And opened. 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 is connected to the load W.
Is hung up and down freely. The supply / exhaust flow paths A1 and B1 are respectively connected to an electromagnetic switching valve 4 having three positions and four ports. The electromagnetic switching valve 4 cuts off both the supply / exhaust paths A1 and B1 in the neutral position, and the supply / exhaust flow is caused by de-energization. The paths A1 and B1 are provided so as to be switchably connected to the pressure source P and the tank T.

The housing hole 2 formed in the valve body 1 has one end opened to the side surface 1A of the valve body 1 and the other end opened to the side surface 1B of the valve body 1, and has a small diameter portion at the center in the axial direction. 2A Both sides have a medium diameter portion 2B, 2C and a large diameter portion 2 facing outward in the axial direction.
D and 2E are formed in a continuous stepped shape, and side surfaces 1A and 1B
Female threads are engraved on the inner peripheral surfaces of the large-diameter portions 2D and 2E which are open to. Reference numeral 4A denotes a tubular body inserted into the storage hole 2 through the opening of the side surface 1A. The poppet valve body 6A is stored inside, and the tip portion thereof reaches the small diameter portion 2A of the storage hole 2 and its outer end portion. Has an engaging portion 5A for engaging a tool (not shown), which is screwed into the large diameter portion 2D by the rotation of the tool engaged with the engaging portion 5A and is detachably attached to the valve body 1, Side 1 by mounting 4A
The opening A is closed to prevent fluid leakage. The cylindrical body 4A has a large diameter hole 7A into which the poppet valve body 6A is slidably inserted and a small diameter hole 8A, which are connected in series and axially penetrate therethrough. The large diameter hole 7A is opened to the outside. At the same time, the small-diameter hole 8A is opened at the tip inserted into the storage hole 2. The external opening of the large-diameter hole 7A is provided by blocking the fluid leakage by the plug member 9A and closing it.

Reference numeral 10A is a valve seat on which the poppet valve body 6A is seated, which is formed in a continuous step portion of the large diameter hole 7A and the small diameter hole 8A of the cylindrical body 4A. Reference numeral 11A is a throttle hole, which is provided in the cylindrical body 4A radially outward from the valve seat 10A forming position in the axial direction, and opens in the medium diameter portion 2B of the storage hole 2 and the cylindrical body 4A. It is connected to the large diameter hole 7A. Reference numeral 12A is a throttle relief hole, which is provided in the cylindrical body 4A in a radial direction with a gap in the axial direction with the throttle hole 11A to connect the load passage A and the large diameter hole 7A. The load passage A and the large-diameter hole 7A are connected in parallel by a throttle hole 11A and a throttle elimination hole 12A. Reference numeral 13A denotes a connection hole, which is provided in the tubular body 4A in the radial direction from the valve seat 10A forming position on the axial front end side to open in the small diameter portion 2A of the storage hole 2 and the tubular body 4A. Small diameter hole 8A
And are connected. As a result, the supply / discharge passage A1 and the load passage A communicate with each other via the valve seat 10A. 17
A is a filter member wound around the outer peripheral surface of the cylindrical body 4A,
The aperture holes 11A and the aperture canceling holes 12A are provided to cover the openings to the outer peripheral surface of the cylindrical body 4A and accommodated in the medium diameter portion 2B of the accommodation hole 2.
The fluid flowing through the throttle hole 11A and the throttle relief hole 12A is provided by being filtered. Then, the filter member 17A is provided so as to be positioned in the axial direction by abutting on the continuous step portion of the small diameter portion 2A and the medium diameter portion 2B of the storage hole 2.

Reference numeral 14 denotes a pilot piston, which is slidably fitted into the small diameter portion 2A of the housing hole 2 so as to face the tip of the small diameter hole 8A of the cylindrical body 4A, and is fitted into the housing hole 2. Hole 2
14A that abuts against the tip of the cylindrical body 4A by blocking between the supply / exhaust flow path A1 and the supply / exhaust flow path B1 that open with a gap in the small diameter portion 2A in the axial direction. A rod portion 15A which is continuously provided in a direction and loosely fits in the small diameter hole 8A of the cylindrical body 4A to come into contact with the head portion of the poppet valve body 6A, and a rod portion 15B which axially opposes the rod portion 15A. Have The pilot piston 14 causes the rod portion 15A to push the poppet valve body 6A detachably from the valve seat 10A by the action of pilot pressure during the control flow in which the fluid flows from the load flow passage A to the supply / discharge passage A1 via the valve seat 10A. The disengagement from the valve seat 10A is set to a predetermined amount by the contact of the piston portion 14A with the tip of the cylindrical body 4A.

A spring 16A is housed in the back portion of the poppet valve body 6A of the large diameter hole 7A, and the poppet valve body 6A is urged in the seating direction of 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 / exhaust passage A1 through the small diameter hole 8A on the head when the fluid flows freely from the supply / exhaust passage A1 to the load passage A via the valve seat 10A. It is detachably provided from the valve seat 10A so that the back portion abuts the stopper member 9A more than a predetermined amount of detachment. Aperture 11
A indicates that the fluid flows through both the predetermined amount of detachment of the poppet valve body 6A during the control flow and the large detachment of the back portion of the poppet valve body 6A during free flow in which the back portion contacts the plug member 4A. The throttle relief hole 12A is the poppet valve body 6 at the time of control flow.
When A is detached by a predetermined amount, the outer surface of the poppet valve body 6A is closed, and when the back portion of the poppet valve body 6A comes into contact with the plug member 9A during free flow, the blockage by the outer surface of the poppet valve body 6A is released in the large separation. A fluid is provided in circulation.

Reference numeral 4B is a cylindrical body inserted into the accommodation hole 2 through the opening of the side surface 1B of the valve body 1, and has a poppet valve body 6B accommodated therein and an engaging portion 5B for engaging a tool. It is detachably attached to the main body 1 and the opening of the side face 1B is closed by blocking fluid leakage. Large diameter hole 7B and small diameter hole 8B of cylindrical body 4B
A valve seat 10B is formed in a step portion continuously provided with the poppet valve body 6
B is urged in the seating direction on the valve seat 10B by the force of the spring 16B, and a throttle hole 11B is radially provided on the outer side in the axial direction from the position where the valve seat 10B is formed, and the throttle hole 11B is accommodated. The load passage B opening to the middle diameter portion 2C of the hole 2 is connected to the large diameter hole 7B. Further, a connection hole 13B is radially provided on the axially distal side from the valve seat 10B forming position, and the connection hole 13B is provided with a supply / discharge channel B1 and a small diameter hole 8B which are open to the small diameter portion 2A of the storage hole 2. And are connected. As a result, the supply / discharge channel B1 and the load channel B are communicated with each other via the valve seat 10B.

Rod portion 15B of pilot piston 14
Is provided by abutting on the head of the poppet valve body 6B by loosely fitting it through the small diameter hole 8B of the cylindrical body 4B, and from the load passage B to the valve seat 10B.
The poppet valve body 6B is provided so as to be detachably pressed from the valve seat 10B by the action of pilot pressure during a control flow in which the fluid flows through the supply / discharge flow path B1 via. The poppet valve body 6B is disengaged from the valve seat 10B by the pilot piston 14
The piston portion 14A is brought into contact with the tip of the cylindrical body 4B to set a predetermined amount. The poppet valve body 6B is a supply / discharge channel B1.
From the valve seat 10B so that when the fluid flows from the valve seat 10B to the load passage B through the free flow, the action of the fluid pressure on the head causes the back portion to come into contact with the plug member 9B more than a predetermined amount of separation during the controlled flow. It is detachable. The throttle hole 11B is provided so that the fluid flows both when the poppet valve body 6B is detached by a predetermined amount during the controlled flow and when the back portion of the poppet valve body 6B is abutted against the plug member 9B during the free flow. A filter member 17B is wound around the outer peripheral surface of the cylindrical body 4B,
The filter member 17B is provided by covering the opening of the throttle hole 11B to the outer peripheral surface of the cylindrical body 4B and accommodating in the medium diameter portion 2C of the accommodating hole 2.
The fluid flowing through the throttle hole 11B is filtered and provided. The filter member 17B is provided so as to be axially positioned by abutting the continuous step portion of the small diameter portion 2A and the medium diameter portion 2C of the storage hole 2.

Next, the operation of this structure will be described. FIG.
In the state shown in FIG. 2, the solenoid operated directional control valve 4 is located at the neutral position to shut off both the supply and discharge flow paths A1 and B1, and the fluid cylinder 3 holds the work W at the rising end and stops the work. The fluid pressure in the rod side chamber 3A of the fluid cylinder 3 caused by the load acts on the back portion 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 back portion with the fluid pressure and the spring 16A force. It is pressed by and is seated on the valve seat 10A, and cuts off between the supply / discharge passage A1 and the load passage 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 the supply / discharge passage B1 and the load passage B from each other.

From the states shown in FIGS. 1 and 2, when the electromagnetic switching valve 4 is energized to switch the supply / exhaust passage B1 to the pressure source P and to connect the supply / exhaust passage A1 to the tank T, the pressure source The fluid P flows through the supply / discharge channel B1 and flows into the small diameter portion 2A of the storage hole 2.
Flow into the connection hole 13B and the small diameter hole 8B of the cylindrical body 4B to act on the head portion of the poppet valve body 6B, and a part of it acts on the pilot piston 14 as pilot pressure, as shown in FIG. The valve body 6B slides to the right against the force of the spring 16B by the fluid pressure acting on the head, and is separated from the valve seat 10B, and the back portion abuts the plug member 9B.
The supply / discharge channel B1 and the load channel B are communicated with each other through the throttle hole 11B and the filter member 17B. Further, the pilot piston 14 slides to the left under the action of pilot pressure, and the rod portion 15A pushes the poppet valve body 6A against the fluid pressure acting on the back portion and the force of the spring 16A to separate it from the valve seat 10A. The disengagement from the valve seat 10A is set by the piston portion 14A of the pilot piston 14 contacting the tip of the cylindrical body 4A, and the throttle hole 11 is provided between the supply / discharge passage A1 and the load passage A.
A and the filter member 17A communicate with each other. At this time,
The throttle relief hole 12A is closed by the outer peripheral surface of the poppet valve body 6A.

The small diameter portion 2 of the storage hole 2 flows through the supply / discharge channel B1.
The fluid flowing into A is throttled and controlled by the throttle hole 11B through the valve seat 10B and the large diameter hole 7B, is filtered by the filter member 17B, flows through the load passage B, and flows into the head side chamber 3B of the fluid cylinder 3.
Fluid flowing into the load passage A from the rod side chamber 3A is filtered by the filter member 17A and is throttle-controlled by the throttle hole 11A, the large diameter hole 7A, the valve seat 10A, the small diameter hole 8A, the connection hole 13A, the storage hole. The fluid cylinder 3 flows through the small-diameter portion 2A of 2 to the tank T from the supply / discharge channel A1, and the fluid cylinder 3 directs the work W downward in FIG. 1 by the meter-in control by the throttle hole 11B and the meter-out control by the throttle hole 11A. Operates downward.

Then, when the work W is lowered to the lower end, the electromagnetic switching valve 4 is de-energized, the operation is returned to the neutral position in FIG. 1 and both the supply and discharge passages A1 and B1 are cut off, the poppet valve body 6A is opened. By the fluid pressure acting on the back and the force of the spring 16A, it slides to the right and seats on the valve seat 10A as shown in FIG.
The supply / discharge channel A1 and the load channel A are shut off from each other. 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 to shut off between the supply / discharge passage B1 and the load passage B. Then, the fluid cylinder 3 holds the work W at the lower end and stops it.

With the work W held in position at the lower end,
When the electromagnetic switching valve 4 is energized to switch the communication of the supply / discharge channel A1 to the pressure source P and the communication of the supply / discharge channel B1 to the tank T, the fluid of the pressure source P flows through the supply / discharge channel A1. Storage hole 2
4 flows into the small diameter portion 2A, flows through the connecting hole 13A and the small diameter hole 8A of the cylindrical body 4A and acts on the head portion of the poppet valve body 6A, and part of it acts on the pilot piston 14 as pilot pressure. As shown, the poppet valve body 6A slides leftward against the fluid pressure acting on the head due to the fluid pressure acting on the head and the force of the spring 16A to separate from the valve seat 10A, and the back portion becomes the plug member 9A. The abutment flow path A1 and the load flow path A are in parallel communication with each other through the throttle hole 11A and the throttle elimination hole 12A. In addition, the pilot piston 14
Is slid to the right by the action of pilot pressure, the rod portion 15B pushes the poppet valve element 6B against the force of the spring 16B, and separates from the valve seat 10B. The piston portion 14A is set in contact with the tip of the cylindrical body 4B, and connects the supply / discharge channel B1 and the load channel B via the throttle hole 11B.

The small diameter portion 2 of the storage hole 2 flows through the supply / discharge channel A1.
The fluid that has flowed into A is filtered by the filter member 17A at a large flow rate that flows through the throttling elimination hole 12A and the throttling hole 11A through the valve seat 10A and the large diameter hole 7A, and flows through the load passage A to the rod of the fluid cylinder 3. The fluid that flows into the side chamber 3A and flows out from the head side chamber 3B into the load flow path B is filtered by the filter member 17B and is throttle-controlled by the throttle hole 11B, and the large diameter hole 7B and the valve seat 1 are provided.
0B, small-diameter hole 8B, connection hole 13B, small-diameter portion 2 of storage hole 2
After flowing through A, the fluid is discharged from the supply / discharge flow path B1 to the tank T, and the fluid cylinder 3 is lifted up in FIG. 1 by the meter-out control by the throttle hole 11B.

Then, when the work W is lifted to the rising end, the electromagnetic switching valve 4 is de-energized and the return operation is returned to the neutral position in FIG. 1 to shut off both the supply and discharge passages A1 and B1, the poppet valve body 6A is closed. By the fluid pressure acting on the back and the force of the spring 16A, it slides to the right and seats on the valve seat 10A as shown in FIG.
The supply / discharge channel A1 and the load channel A are shut off from each other. 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 to shut off between the supply / discharge passage B1 and the load passage B. Then, the fluid cylinder 3 holds the work W at the rising end and stops.

With this operation, when the cylinder 4A having the throttle hole 11A and the throttle release hole 12A is replaced and the same cylinder 4B having the throttle hole 11B is attached to the valve body 1,
When the poppet valve body 6A is detached from the valve seat 10A by a predetermined amount and the fluid flows freely from the supply / discharge channel A1 to the load channel A during a controlled flow of the fluid from the load channel A to the supply / discharge channel A1 Since the fluid flows through the throttle hole 11B regardless of the large disengagement of the poppet valve body 6B from the valve seat 10B, the fluid is throttle-controlled both during the control flow and the free flow.
By exchanging the cylindrical body 4A, a throttling action can be given during free flow, an increase in the number of valve points due to a change in valve function can be suppressed, and cost can be reduced.

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 arranged in the cylinders 4A and 4B.
Can be attached to the valve body 1 as the
The fluid flowing through the throttle holes 11A and 11B and the throttle relief hole 12A can be filtered, and the valve body 1 of the filter members 17A and 17B can be filtered.
Can be installed easily. Also, the cylindrical body 4A
The cylindrical body 4B to be replaced with the cylindrical body 4B may have a different structure depending on whether or not it has the aperture canceling hole 12A, and can be shared.

In the embodiment of the present invention, the valve body 1
Although the cylindrical body 4A and the cylindrical body 4B are attached to the above, it is needless to say that one cylindrical body 4A or 4B may be attached if necessary. In this case, the opening of the housing hole 2 to which the cylindrical body 4B or 4A is not attached may be closed so as to prevent fluid leakage, and the closing member and the pilot piston 14 may be provided in contact with each other.

[0024]

As described above, according to the present invention, the cylindrical body having the restriction hole and the restriction elimination hole is provided so as to be interchangeable with the cylindrical body having the restriction hole. It is possible to exert an action, it is possible to suppress an increase in the number of valve points due to a change in valve function, and it is possible to achieve cost reduction.
Further, the mutually replaceable cylindrical bodies may have a different configuration depending on whether or not they have a restriction eliminating hole, and can be shared.

Further, by adopting the structure in which the filter member for filtering the fluid is wound around the outer peripheral surface of the cylindrical body, the filter member can be mounted on the valve main body as the cylindrical body is mounted on the valve main body. The attachment of the member to the valve body can be simplified.

[Brief description of 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.

FIG. 3 is a vertical sectional view showing an operating state of the pilot operated check valve of FIG.

FIG. 4 is a vertical cross-sectional view showing an operating state different from that in FIG.

[Explanation of symbols]

 1 Valve Body 1A, 1B Side 2 Storage 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 Throttling Hole 12A Throttle Resolving Hole 14 Pilot piston 14A Piston part 15A, 15B Rod part A, B Load flow path A1, B1 Supply / discharge flow path

Claims (2)

[Claims] 1. A fluid supply / discharge channel and a load channel connected to a fluid actuator are provided in a valve body at a storage hole formed in the valve body with an axial gap, and the storage hole is provided in the valve. It is provided by opening on the side of the main body, and the cylinder body containing the poppet valve body inside is inserted from the opening of this side face into the storage hole and detachably attached to the valve body. Is closed so as to prevent fluid leakage, and the cylindrical body has a large diameter hole into which the poppet valve body is slidably inserted and an axially continuous connection to the large diameter hole. It has a small diameter hole opened at the tip to be inserted into the mounting hole, and a valve seat on which the poppet valve body is seated is formed at the stepped portion connecting the large diameter hole and the small diameter hole. The load passage opening to the storage hole is connected, and the small-diameter hole of the cylinder is connected to the supply / exhaust flow passage opening to the storage hole. The pilot piston is slidably inserted into the housing hole so as to face the tip of the small-diameter hole of the cylindrical body that is provided in communication through the valve seat. It has a rod part that is connected to the piston part in the axial direction and passes through the small diameter hole of the cylindrical body and comes into contact with the poppet valve head part, and the fluid flows from the load flow path to the supply / discharge flow path through the valve seat. When the control flow, the rod part pushes the poppet valve body detachably from the valve seat by the action of pilot pressure, and the detachment from this valve seat is set to a predetermined amount by the contact of the piston part with the tip of the cylinder body. The poppet valve body is provided at the position during control flow due to the action of the fluid pressure flowing from the supply / exhaust flow passage through the small diameter hole on the head when the fluid flows freely from the supply / exhaust flow passage to the load flow passage through the valve seat. It is larger than the fixed amount of detachment and can be detached from the valve seat. The connection with the load passage to be opened is provided in parallel with the throttle body and the throttle relief hole, which are provided in the cylindrical body with a gap in the axial direction, and the throttle hole is located at the poppet valve body during control flow. The fluid is circulated both in the fixed amount of detachment and in the poppet valve detachment during free flow, and the restriction relief hole is closed by the poppet valve disc when the poppet valve disc is detached by a predetermined amount during the control flow and at the time of free flow. Pilot-operated non-return valve characterized in that a fluid is circulated when the poppet valve body is released to provide a fluid passage, and a tubular body having the throttle hole and the throttle release hole is provided so as to be interchangeable with the tubular body having the throttle hole. valve. 2. A pilot operation according to claim 1, wherein a filter member for filtering a fluid is wound around an outer peripheral surface of a cylindrical body which is inserted into the storage hole and is detachably attached to the valve body. Check valve.