JPS5824673B2 - pressure control valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a balanced piston type pressure control valve that regulates the upper limit of the circuit pressure of a hydraulic circuit that performs meter-out control of the speed of an actuator such as a cylinder using a flow rate control valve.

BACKGROUND ART Conventionally, a meter-out circuit circuit in which the outlet flow rate of an actuator such as a cylinder is controlled by a flow control valve [a pressure control valve that controls the upper limit of pressure as shown in FIG. 1 is known].

In FIG. 1 showing an example of a conventional meter-out circuit,
A 4-port 2-position switching valve 2 is installed at both ports of the piston of a double-rod double-acting cylinder 1 as an actuator.
The A and B ports of are connected to each other, and the pump port is connected to a constant volume pump 3, and the pump port pressure is regulated to below the circuit maximum pressure by the IJ IJ-) valve 4 as the pressure control valve, Also, the switching valve 2
The tank ports of each are connected to a tank 6 via a flow control valve 5.

In this case, during cylinder speed control, the IJ pressure is always the constant circuit maximum pressure regardless of the magnitude of the cylinder load pressure, and the excess oil is returned to the tank 6 from the relief valve 4 at high pressure. The circuit efficiency is low and energy loss is high, which causes the tank oil temperature to rise.

Further, even if a pressure compensation type flow control valve is used as the flow control valve 5, the pressure difference between the inlet and the outlet fluctuates as the cylinder load pressure fluctuates, so the disadvantage that the controlled flow rate fluctuates somewhat cannot be avoided.

The purpose of this invention is to control the flow rate of pressure oil flow at the outlet of the actuator without losing the leaf function that allows the circuit maximum pressure to be freely set from the outside when meter-out controlling an actuator such as a cylinder with a flow control valve. The IJ IJ-F pressure on the actuator inlet side is variably controlled to a pressure value lower than the maximum pressure setting value of the circuit according to the valve inlet side pressure, and the pressure at the pre-distribution flow control valve inlet is controlled to ensure stable operation of the flow control valve. To maintain an almost constant set pressure value that is as small as possible above the required value, and when the load pressure is high or when the inlet side of the flow control valve is closed by a switching valve, etc., use a normal balance piston type relief valve. Another object of the present invention is to provide a pressure control valve that can perform relief operation at the highest pressure setting value in the circuit.

That is, the pressure control valve of the present invention is a pressure control valve that controls the pressure on the inlet side of the actuator of a meter-out circuit in which the outlet pressure oil flow of an actuator such as a cylinder is controlled by a flow rate control valve, and is an adjustment valve for setting the circuit maximum pressure. The pilot poppet valve regulates the upper limit of the pilot pressure on the back of the main valve piston, so that a part of the inlet side pressure is transferred to the tank so that the inlet side pressure does not exceed a set value. The balance piston type pressure control valve is characterized by releasing a part of the pilot pressure to the tank in accordance with the pressure on the flow control valve inlet side of the actuator outlet pressure oil flow. Another pilot valve is provided which controls the pilot pressure to a pressure value below the upper limit according to the pressure, and this another pilot valve receives the flow control valve inlet pressure on one end face and receives the pressure on the other end face side. has a slidable spool pressed by a spring adjustable from
As this spool moves against the splash due to pressure on the inlet side of the flow rate control valve acting on the one end face, the spool controls the throttle to open the pilot chamber of the pilot poppet valve communicating with the back of the main valve piston to the tank. The reason is that the body is equipped with a part on the torso.

In this way, in the pressure control valve of the present invention, the IJ of the circuit
The IJ-F pressure is controlled according to the load pressure of the actuator below the maximum pressure setting value of the circuit, so that the inlet pressure of the flow control valve can always be maintained at a substantially constant value determined by the spring force of the spring. This is what I did.

An embodiment of the present invention will be described with reference to FIG. 2. In FIG. 2, the same reference numerals as in FIG.
A meter-out circuit installed in place of the IJ-F valve 4 is shown.

A pressure control valve 42 according to the present invention comprises a balanced piston type relief valve 41 having a pilot poppet valve 24 which is not much different from a normal one, and further includes another pilot valve 8.

First, the balance piston type relief valve 41 has a valve main body 38.
a main valve body 33 slidable by its piston portion 37 within;
is pressed from the back by the main valve spring 34 in the main valve spring chamber 32 to bring the tip of the main valve body into contact with the valve seat 35, and the inside of the spring chamber 32 is communicated with the tank port 36 through the main valve body passage. The opening between the inlet port 40 and the tank port 36 is controlled by opening and closing the valve seat 35.

A valve chamber 39 formed on the back surface of the piston section 37 communicates with an inlet port 40 through a small hole 44 provided through the piston section 37, and the upper limit pressure of this valve chamber 39 is regulated by the pilot poppet valve 24. It's Nishide.

That is, this pilot poppet valve 24 includes a poppet valve 23 that is pressed against a valve seat 28 by a spring 30 that is freely adjustable by an adjustment handle 31, and a spring chamber 29 in which a spring 30 is disposed is connected to a tank via a main valve spring chamber 32. The tip tapered surface 25 side of the poppet valve 23 communicates with the pilot chamber 26 through a passage 27 bored in the valve seat 28.
This pilot chamber 26 is communicated with the valve chamber 39 on the back surface of the main valve body piston portion described above.

In addition to the above-described configuration, the pressure control valve 42 of the present invention further includes a pilot valve 8 consisting of a spool 9 incorporated into the body 7, a pressure regulating spring 10, an adjusting screw 11, and the like.

In the pilot valve 8, the spool 9 has a small-diameter protrusion 12 at its tip, and a sliding piston portion 15 and a tapered portion 18 are sequentially formed on the back of the spool 9 through the small-diameter portion. The portion 12 can come into contact with the inner surface 14 of the plug 13 fitted in the body 7 and forms a valve chamber 16 between the sliding piston portion 15 and another valve chamber 16 between the piston portion 15 and the tapered portion 18. A valve chamber 19 is formed and communicated with the pilot chamber 26, and a throttle control section 21 is formed between the land 20 of the tapered section 18 and the body inner hole, and a pressure regulating spring communicating with the tank 6 is provided on the back surface of the tapered section 18. A chamber 22 is constituted, and the back surface thereof is compressed by a pressure adjustment spring 10 which can be freely adjusted by an adjustment screw 11.

The valve chamber 16 is communicated by a conduit 43 with a port 17 into which the load pressure at the inlet of the flow control valve 5 is introduced, so that the spool 9 receives this load pressure on its front end face and receives the spring force of the spring 10 from the back. The force due to this load pressure is opposed to the

In the pressure control valve according to the present invention shown in FIG. 2, the setting of the maximum circuit pressure P1, that is, the setting of the upper limit of the IJ-F pressure, is freely carried out by regulating the pressure of the poppet valve 23 using the handle 31, as in the usual case.

When the circuit pressure P2 led to the inlet port 40 is below the maximum pressure setting P, the pressure in the valve chamber 39 at the back of the main valve piston section 37, that is, the pilot pressure acting on the pilot poppet valve 23, is the circuit pressure P2. , the poppet valve 23 remains closed as long as the pressure in the valve chamber 39 does not exceed the set pressure of the poppet valve 23.

The state in which this poppet 23 is closed, that is, the circuit pressure P
2 is below P1, the pressure control valve 4 of the present invention
2 controls the pilot pressure of the relief valve 41 according to the load pressure ΔP by operating the pilot valve 8, and sets the circuit pressure P2 to a constant value P3 that is higher than the load pressure ΔP and the minimum pressure necessary for stable operation of the flow rate control valve 5. It is designed to follow the sum of .

That is, the pressure P3 on the inlet side of the flow control valve 5 is introduced into the valve chamber 16 of the pilot valve 8 through the conduit 43 and the port 17, and the spool 9, whose pressure is regulated by the spring 10, receives this pressure P3. The opening degree of the throttle control section 21 in the middle is controlled, and the pressure in the valve chamber 39, that is, the pilot pressure, is set to a pressure corresponding to the load pressure ΔP.

In this case, the difference P2-P3 between the circuit pressure P2 and the flow control valve inlet pressure P3 is the load pressure ΔP.

When the pressure receiving area of the spool 9 is A1 and the spring force of the spring 10 is F, the pressure of the spring 10 is adjusted so that P3-F/A is satisfied.

When the pressure P3 rises and reaches the set pressure of the pilot valve 8, the spool 9 operates, and the valve chamber 1 is
9, the pilot chamber 26 is opened from the pressure regulating spring chamber 18 to the tank 6 at a controlled opening degree.

As a result, the pressure in the valve chamber 39 at the back of the main valve piston part 37 decreases, and the main valve body 33 operates against the main valve spring 34 to open the valve seat 35, and the gap between the ports 40 and 36 is reduced. IJ I
Increase J-F flow rate.

While the spool 9 is operating, the flow of pressure oil is through the port 40.
→ Small hole 44 → Valve chamber 39 → Pilot chamber 26 → Valve chamber 19 →
The flow flows from the throttle control section 21 to the pressure regulating spring chamber 22 to the spring chamber 29 to the main valve spring chamber 32 to the port 36 to the tank 6, and the pressure difference generated before and after the small hole 44 causes a relief operation of the main valve body 33.

This IJ IJ-f operation is performed in a circuit pressure range lower than the circuit maximum pressure setting value P1, and in this case, the load pressure ΔP
The sum of the flow rate control valve inlet pressure P3 and the circuit maximum pressure setting value P
, the circuit pressure P2 will be controlled to P 2 "" F / A + ΔP within a range not exceeding .

In this way, the relief pressure (circuit pressure) P2 is approximately equal to the sum of the load pressure ΔP and the constant value F/A, and when the flow control valve 5 is of the pressure compensation type, the value of this F/A is By setting the pressure above the minimum pressure value for ensuring stable operation, the accuracy of flow rate control can be significantly improved.

On the other hand, when the cylinder 1 reaches the stroke end and stops, there is no pressure oil flow from the cylinder, so the flow control valve 5
The pressure at the inlet becomes zero, that is, P3=0, and as a result, the spool 9 is pushed and moved by the spring 10 until its tip protrusion 12 abuts the plug 13, and the throttle control section 21 is closed.

Therefore, after this, the circuit pressure P2 is regulated to the maximum pressure value P1 set in the pilot poppet valve 24 by the unique operation of the IJ IJ-F valve 41.

As described above, according to the pressure control valve of the present invention, the relief pressure in the meter-out circuit is controlled by the pressure on the flow control valve inlet side below the maximum pressure set value, so when the cylinder load pressure decreases, the relief pressure increases. In this case, the flow control valve inlet pressure on the cylinder outlet side is maintained at a constant value higher than the minimum pressure value required for stable operation of the flow control valve, and therefore the I
J IJ-F Excess oil is returned to the tank at low pressure, improving circuit efficiency and reducing energy loss. If a pressure compensation type flow control valve is used, the control accuracy will be significantly improved. Even if a simple throttle valve without pressure compensation is used, it is possible to obtain a flow rate control effect similar to that of a throttle valve with pressure compensation.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an example of a conventional meter-out circuit, and FIG. 2 is an explanatory diagram in which the meter-out circuit is added to a vertical side view showing an embodiment of the present invention. 8... Pilot valve, 9... Spool, 10... Pressure regulating spring, 11... Adjusting screw, 16... Valve chamber, 17...port,
18...Curved taper part, 19...Curved valve chamber, 20...
・Valve body land part, 21 ・Bending/throttle control part, 22...
・・Spring chamber, 23・4・Pilot poppet valve, 39・
... Valve chamber, 40... Curved loport, 41... Curved balance piston type relief valve.

Claims (1)

[Claims] 1 A pressure control valve that controls the pressure at the inlet side of the actuator of a meter-out circuit in which the outlet pressure oil flow of an actuator such as a cylinder is controlled by a flow rate control valve, and is equipped with a pilot poppet valve that can adjust the pressure for setting the circuit maximum pressure. Balanced piston type pressure control that uses this pilot poppet valve to regulate the upper limit of the pilot pressure on the back of the main valve piston and releases a portion of the inlet side pressure to the tank so that the inlet side pressure does not exceed a set value. In the valve, the pilot pressure is controlled to a pressure value below the upper limit according to the load pressure by releasing a part of the pilot pressure to the tank according to the pressure on the flow control valve inlet side of the actuator outlet pressure oil flow. another pilot valve having a slidable spool receiving the flow control valve inlet pressure on one end face and pressed by an adjustable spring from the other end face; The spool is a throttle control unit that opens a pilot chamber of the pilot poppet valve communicating with the back of the main valve piston to a tank as the spool moves against the spring due to pressure on the inlet side of the flow control valve acting on the one end face. A pressure control valve characterized in that the body is equipped with a.