JPH0627892Y2 - Pilot operated check valve - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a pilot operated check valve which is used for holding the position of hydraulic cylinders used above and below a boom of a construction machine.

[Conventional technology]

A conventional pilot operated check valve of this type is shown in FIG.

The pilot operated check valve P is provided between the pressure chamber S1 on the bottom side of the hydraulic cylinder S and the pilot operated directional control valve V. The pilot operated check valve P includes a pilot portion P1 connected to a pilot portion VP1 of a pilot operated directional control valve V, and a pressure chamber S1 on the bottom side when pilot hydraulic pressure does not act on the pilot portion P1.
And a pilot-operated directional control valve V at a position P2, and a position P3 that connects the bottom-side pressure chamber S1 and the pilot-operated directional control valve V when a pilot hydraulic pressure acts on the pilot portion P1. Have and.

Therefore, when the pilot operated type directional control valve V is operated to the switching position V1 by the pilot hydraulic pressure, the pilot operated check valve P is switched from the position P2 to the position P3 almost at the same time. Overload relief valve ORV
1 and ORV2 are for preventing an overload that occurs during operation of the pilot operated directional control valve V.

In the pilot operated check valve P having such a configuration, when the pilot operated directional control valve V is at the neutral position V0, the hydraulic pressure of the pressure chamber S1 on the bottom side of the hydraulic cylinder S is set at the position P2. The hydraulic cylinder S is held to prevent the hydraulic cylinder S from descending. Also, when pilot hydraulic pressure from a remote control valve (not shown) is applied to the pilot portion VP1 of the pilot operated type directional control valve V, the pilot operated type directional control valve V is switched from the neutral position VO to the switch position V1. Therefore, the pressure oil of the pump P0 is supplied to the pressure chamber S2 on the head side of the hydraulic cylinder S, and the pilot pressure also acts on the pilot portion P1 of the pilot operated check valve P to switch from the position P2 to the position P3. Therefore, the hydraulic pressure in the pressure chamber S1 on the bottom side is discharged to the tank T0.

[Problems to be solved by the device]

In the conventional technique described above, the pilot operated check valve P also operates when the pilot operated directional control valve V is switched. In the state of FIG. 3, when the pilot operated directional control valve V is at the neutral position V0, the pump P0 is unloaded, so that the pilot operated check valve P and the pilot operated directional control valve V are connected. The hydraulic pressure between them is low. The hydraulic pressure in the pressure chamber S1 on the bottom side is high due to the load acting on the hydraulic cylinder S. Therefore, when the pilot operated check valve P is switched, the high pressure oil in the pressure chamber S1 on the bottom side is suddenly released to the low pressure side.
An impact occurs on the hydraulic cylinder S.

The shock generated in the hydraulic cylinder S is dangerous, such as shaking the boom. Therefore, a counterbalance valve (actual fairness 1-
No. 13885), there is also a control throttle part provided so as not to suddenly release the hydraulic pressure of the pressure chamber S1 on the bottom side when the pilot operated check valve P is switched from the position P2 to the position P3.

However, even in the case where the control throttle portion is provided, if a large hydraulic pressure (surge hydraulic pressure due to load vibration) acts on the pressure chamber S1 on the bottom side at the position shown in FIG. 3, the hydraulic cylinder S is damaged. It is necessary to provide the mold check valve P with an overload relief valve ORV. Many of the pilot operated check valves P are fixed to the hydraulic cylinder S, and the drain circuit D1 is required for the overload relief valve ORV, which causes a problem that the circuit configuration becomes complicated.

[Means for Solving the Problems]

A technical means of the present invention for solving the above-mentioned problems is to provide an inner hole in a main body, in which a first port to which a pilot operated type directional control valve is connected and a second port to which a hydraulic cylinder is connected are opened. An overload relief valve is connected between the 1-port and the directional control valve, and a spool having a poppet valve portion that abuts a valve seat provided on the first port side is slidably fitted in the inner hole. A pilot portion is arranged at one end of the spool, and a pressing portion is arranged at the other end, and a control throttle portion is formed between the second port and the valve seat.
In a pilot operated check valve in which a cross-sectional area of the throttle control throttle portion is formed larger than a cross-sectional area of the valve seat of the poppet valve, a chamber is formed between the control throttle portion and the poppet valve,
When the poppet valve is seated on the valve seat, the control throttle portion forms a minute throttle between the chamber and the second port.

[Action]

According to the present invention having the above means, a chamber is formed between the control throttle portion and the poppet valve, and when the poppet valve is seated on the valve seat, a minute throttle is formed between the chamber and the second port. This prevents a sudden release of high pressure oil from the bottom pressure chamber when the pilot operated check valve is activated, prevents the hydraulic cylinder from impacting, and controls the hydraulic pressure in the bottom pressure chamber. If the chamber between the throttle and the poppet valve is always operated and the spool operation by this hydraulic pressure is made lower than the set value of the overload relief valve of the pilot operated directional control valve, the surge pressure generated in the hydraulic cylinder will be pilot operated. Of the pilot operated check valve as the surge pressure is released to the tank by the overload relief valve of the pilot operated check valve. It is possible to omit the leaf valve.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. 1 showing a sectional view of the embodiment of the present invention and FIG. 2 showing a circuit diagram. In addition,
The same parts as the conventional ones are designated by the same reference numerals and the description thereof is omitted.

In FIG. 1 showing a sectional view of a pilot operated check valve P ′, a main body 10 has an inner hole 11 into which a spool 12 is slidably fitted. A first port VH to which the pilot operated directional control valve V is connected and a second port H1 to which the hydraulic cylinder S is connected are opened in the inner hole 11.
A valve seat 13 is provided at the opening end of the first port VH of the inner hole 11.
And a poppet valve 14 formed on the spool 12 is in contact with the valve seat 13 to close between the second port H1 and the first port VH. At the second port H1,
A control throttle portion 15 formed by the valve seat 15a and the notch 15b of the spool 12 is continuously provided. This control diaphragm unit 1
A chamber 16 is provided between the valve seat 5 and the valve seat 13. The chamber 16 is slightly moved to the second position via the notch 15b of the control throttle portion 15 in a state where the poppet valve 14 is in contact with the valve seat 13.
It communicates with port H1.

At the other end of the spool 12 at the left end of the main body 10, a spring B10, B11 released to the atmosphere and a piston B1 slidably fitted in a pressure chamber B12 that is in constant communication with the second port H1.
A pressing portion constituted by 3 and 3 is provided. This pressing portion applies the pressing force of the springs B10 and B11 to the hydraulic cylinder S.
The pressure force of the bottom side pressure chamber S1 is added to the pressure force of the pressure chamber B12, and the pressure force is complemented according to the fluctuation of the hydraulic pressure of the bottom side pressure chamber S1.

The cross-sectional area A1 of the valve seat 13 is smaller than the cross-sectional area A2 of the control throttle portion 15 (cross-sectional area A1 <cross-sectional area A2). Therefore, when a surge pressure acts on the chamber 16, a difference A0 in cross-sectional area between the cross-sectional areas A1 and A2 (cross-sectional area A2
-The cross-sectional area A1 = the cross-sectional area difference A0) becomes the pressing force, and when this pressing force exceeds the sum of the pressing force by the springs B10, B11 and the hydraulic pressure acting on the pressure chamber 12, the spool 12 Moves to the left and poppet valve 14
Moves away from the valve seat 13. The operating pressure of the spool 12 is lower than the set value of the overload relief valve ORV1 of the pilot operated directional control valve V. Therefore, when the surge of the hydraulic cylinder S acts on the pilot operated check valve P, the overload relief valve ORV1 acts.

The pilot portion P1 disposed at the right end of the main body 10 at one end of the spool 12 is a pilot chamber C2 formed by a sliding portion C1 slidably fitted in the inner hole 11, and the pilot chamber C2 and the pilot chamber C2. The restrictor C3 is provided between the restrictor C3 and the part VP1. This pilot part P
No. 1 moves the spool 12 in the right direction when the hydraulic pressure of the pilot portion VP1 acts.

The operation set pressure of the pilot operated check valve P'is slightly lower than the operation set pressure of the pilot operated type directional control valve V.

According to the present invention having the above configuration, the surge pressure acting on the pressure chamber S1 on the bottom side is removed as follows.

When the hydraulic cylinder S is held in a predetermined extended state when the pilot operated directional control valve V is at the neutral position V0, hydraulic pressure is generated in the pressure chamber S1 on the bottom side by the load acting on the hydraulic cylinder S. . This hydraulic pressure acts on the chamber 16 via the second port H1 and the notch 15b of the control throttle unit 15. Also, from the second port H1 to the pressure chamber B1
Also works on 2. Therefore, the spool 12 is acted on the spool 12 from the side of the pressing portion B thereof by adding both the pressing force of the springs B10 and B11 and the pressing force of the pressure chamber B12. (Hereinafter, referred to as additional pressing force.) When the pressing force from the chamber 16 by the hydraulic pressure of the pressure chamber S1 on the bottom side exceeds the additional pressing force, the spool 12 moves to the left and the poppet valve 14 moves from the valve seat 13 to the valve seat 13. Move away. Therefore, the hydraulic pressure acting on the pressure chamber S1 on the bottom side acts on the overload relief valve ORV1 shown in FIG. Therefore, when the hydraulic pressure (surge pressure) acting on the pressure chamber S1 on the bottom side exceeds the set value of the overload relief valve ORV1, it is discharged to the tank T0.

Next, the impact when the hydraulic cylinder S descends is removed as follows.

Pilot part VP1 of pilot operated type directional control valve V
When hydraulic pressure from the remote control valve is applied to the pilot operated directional control valve V, the pilot operated directional control valve V starts to switch from the neutral position V0 to the switching position V1. The hydraulic pressure from the remote control valve also acts on the pilot portion P1 of the pilot operated check valve P,
The spool 12 is operated to the left. Therefore, immediately before the pilot operated directional control valve V is switched, the pressure chamber S1 on the bottom side has the second port H1, the control throttle unit 15,
Via the poppet valve 14 and the first port VH, it communicates with the pilot operated type directional control valve V, and the bottom side pressure chamber S
The hydraulic pressure from 1 to the pilot operated type directional control valve V is set to the hydraulic pressure of the pressure chamber S1 on the bottom side. After that, the pilot operated directional control valve V starts to switch from the neutral position V0 to the switching position V1. For this reason, the hydraulic pressure in the pressure chamber S1 on the bottom side is not suddenly released to the low pressure side, so that vibration when starting the descent from the stopped position of the hydraulic cylinder S is prevented.

After starting in this way, the switching amount of the pilot operated directional control valve V and the pilot operated check valve P increases. At this time, since the change of the opening area of the control throttle portion 15 of the pilot operated check valve P is made larger than the change of the opening area of the pilot operated type directional control valve V, the speed of the hydraulic cylinder S after starting is increased. The control of (1) becomes a value according to the oil pressure (the operation amount of the remote control valve) of the remote control valve that acts on the pilot operated directional control valve V.

The check valve P6 provided in the inner hole 12 that communicates with the first port VH formed in the spool 12 is provided when the pilot operated directional control valve V is operated from the neutral position V0 to the switching position V2. Pressure chamber S1 on the bottom side of the hydraulic cylinder S
The pressure oil of the pump P0 is supplied to.

[Effect of device]

According to the present invention, a main body is provided with an inner hole in which a first port to which a pilot operated directional control valve is connected and a second port to which a hydraulic cylinder is connected are opened, and between the first port and the directional control valve. An overload relief valve is connected, and a spool having a poppet valve portion that abuts a valve seat provided on the first port side is slidably fitted into the inner hole, and a pilot portion is provided at one end of the spool. A pressing portion is arranged at the other end, and a control throttle portion is formed between the second port and the valve seat, and the cross-sectional area of the throttle control throttle portion is the valve seat of the poppet valve. In the pilot operated check valve formed larger than the cross-sectional area of, a chamber is formed between the control throttle portion and the poppet valve,
When the poppet valve is seated on the valve seat, the control throttle portion is configured to form a minute throttle between the chamber and the second port, so that the hydraulic pressure in the pressure chamber on the bottom side of the hydraulic cylinder enters the chamber. It always works. Therefore, before the pilot operated type directional control valve is switched from the neutral position to the switched position, the hydraulic pressure between the pressure chamber on the bottom side and the pilot operated type directional control valve is made uniform and the high pressure oil in the pressure chamber on the bottom side is made uniform. Is no longer released to a low pressure, which has the effect of preventing the occurrence of vibration when the hydraulic cylinder starts to descend.

Further, since the cross-sectional area of the control throttle portion is made larger than the diameter of the valve seat of the poppet valve, even if surge pressure acts on the pressure chamber S1 on the bottom side, the surge pressure causes the poppet valve of the spool to move from the valve seat. Since they are separated from each other, the overload relief valve of the pilot operated type directional control valve can be shared as the overload relief valve of the hydraulic cylinder. Therefore, there is an effect that the circuit configuration is simplified.

Further, since the control throttle portion is configured to connect the chamber and the second port via the minute throttle when the poppet valve is seated on its valve seat, the control throttle portion with respect to the movement of the spool of the control throttle portion. The opening area of the pilot operated directional control valve can be selected to be larger than the change in the opening area when the pilot operated directional control valve is switched. It has the effect that it can be configured to be performed by.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is a hydraulic circuit diagram using the embodiment of the present invention, and FIG. 3 is a conventional hydraulic circuit diagram. S ... hydraulic cylinder, S1 ... bottom pressure chamber, V ... pilot operated directional valve, P ... pilot operated check valve, P1 ... pilot part, B ... pressing part, ORV ... ... Overload relief valve, 10 ... main body, 11 ... inner hole, 12 ... spool, 13 ... valve seat, 14 ... poppet valve, 15 ... control throttle, 16 ... chamber.

Claims (1)

[Scope of utility model registration request] 1. A main body is provided with an inner hole in which a first port to which a pilot operated directional control valve is connected and a second port to which a hydraulic cylinder is connected are opened, and between the first port and the directional control valve. Is connected to an overload relief valve, and a spool having a poppet valve portion that comes into contact with a valve seat provided on the first port side is slidably fitted into the inner hole, and a pilot portion is arranged at one end of the spool. And a pressing portion is arranged at the other end, a control throttle portion is formed between the second port and the valve seat, and a cross-sectional area of the throttle control throttle portion is the valve of the poppet valve. In the pilot operated check valve formed to be larger than the cross-sectional area of the seat, a chamber is formed between the control throttle portion and the poppet valve,
The pilot operated check valve, wherein the control throttle portion forms a minute throttle between the chamber and the second port when the poppet valve is seated on the valve seat.