JPH0450444B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to logic valves.

Fig. 2 shows an example of a control circuit equipped with a conventional logic valve, where a is the logic valve, b is the housing, c is the cover, d is the poppet, e is the spring, f is the supply port, g is the load port, and h is the control port, i is the actuator, j is the pressure reducing valve,
k indicates a pressure source, l indicates a pump, m indicates a directional control valve, and n indicates a tank.

In this control circuit, the flow rate flowing between supply port f and load port g is determined by the pressure difference between supply port f and load port g and the control pressure applied to control port h. The pressure applied to actuator i changes depending on the load on actuator i, so in order to control the flow rate between ports g and f, the control pressure is changed by operating pressure reducing valve j according to changes in the load on actuator i. There was a problem that I had to do it.

SUMMARY OF THE INVENTION In order to solve the above problem, the present invention provides a logic valve that can control the flow rate between a supply port and a load port without being affected by changes in supply port pressure or load port pressure.

The present invention will be specifically described below with reference to an embodiment shown in FIG.

In FIG. 1, 1 is a logic valve, 6 is a variable throttle, 26 is an actuator, 27 is a directional control valve, 28 is a pump, and 29 is a tank. The poppet 4, which is slidably fitted in an oil-tight manner into a guide hole 10 formed in the housing 2, is biased toward the seat 30 by a spring 20 disposed behind it, and the front seat of the poppet 4 is By changing the distance between the surface and the seat 30, the amount of oil flowing through this distance from the supply port 7 to the load port 8 or from the load port 8 to the supply port 7 is controlled. A poppet guide 14 is bored on the inner surface of the cover 3 that covers the open end of the housing 2.
is slidably fitted in an oil-tight manner into the inner hole 18 of the poppet 4, and the inner surface of the cover 3 and the poppet guide 14
A second chamber 9 is delimited behind the poppet 4 by the outer surface of the poppet and the housing 2, and a first chamber 23 is delimited by the inner bore 15 of the poppet guide 14 and the inner bore 18 of the poppet 4. . The chamber 21 is delimited by stuffing the plug 5 into the outlet of the hole 12 formed in the cover 3. One end of this chamber 21 is communicated with the first chamber 23 via the oil passage 16, the other end is communicated with the second chamber 9 via the oil passage 13, and the control port 17 is opened in the center thereof. A shuttle valve is constructed by movably storing a ball 22 in the chamber 21. The ball 22 is moved to the right and seated on the seat 25 provided on the plug 5 to communicate the oil passage 16 with the control port 17, and the ball 22 is moved to the left and seated on the seat 24 provided on the cover 3. By seating the oil passage 13
can be communicated with the control port 17. The supply port 7 communicates with a first chamber 23 via a first orifice 19 provided in the poppet 4;
The load port 8 is communicated with a second chamber 9 via a second orifice 11 provided in the housing 2. When the poppet 4 is seated on the seat 30, the pressure receiving area of the poppet 4 which receives the internal pressure of the supply port 7 is made equal to the pressure receiving area of the poppet 4 which receives the internal pressure of the first chamber 23, and the pressure receiving area of the poppet 4 which receives the internal pressure of the load port 8 is made equal to the pressure receiving area of the poppet 4 which receives the internal pressure of the first chamber 23. The pressure receiving area is made equal to the pressure receiving area of the poppet 4 which receives the internal pressure of the second chamber 9.

Now, a case where the supply port 7 is communicated with the tank 29 by operating the directional control valve 27 and the pressure inside the actuator 26 is acting on the load port 8 will be described. When the variable throttle 6 is closed in this state, the pressure in the first chamber 23 becomes equal to the pressure in the supply port 7 via the orifice 11, and the pressure in the second chamber 9 is transferred via the orifice 19 to the load port 8. Since the pressure in the oil passage 23 becomes greater than the pressure in the oil passage 16, the ball 22 moves to the left and seats on the seat 24 to occupy the position shown in the figure. The pressure receiving area of the poppet 4 which receives the internal pressure of the supply port 7 is equal to the pressure receiving area of the poppet 4 which receives the internal pressure of the first chamber 23, and the pressure receiving area of the poppet 4 which receives the internal pressure of the load port 8 receives the internal pressure of the second chamber 9. Since the area is equal to the pressure-receiving area of the poppet 4, the poppet 4 is not subjected to hydraulic pressure, but is pushed and pushed only by the elastic force of the spring 20, and is seated on the seat 30, resulting in the state shown in the drawing.

Next, when the variable throttle 6 is opened and the pressure in the control port 17 is reduced, the pressure oil in the load port 8 enters the chamber 21 of the shuttle valve via the second orifice 11, the second chamber 9, and the oil passage 13. By flowing out from the control port 17, the pressure in the second chamber 9 becomes lower than the pressure in the load port 8, and the poppet 4 overcomes the elastic force of the spring 20 and moves away from the seat 30. The oil in the load port 8 thus flows to the supply port 7 between the seat surface of the poppet 4 and the seat 30. In this case, the flow rate through the second orifice 11 is proportional to the opening degree of the variable restrictor 6, and the pressure difference between the supply port 8 and the second chamber 9 is
is proportional to the flow rate through the orifice 11. Therefore, regardless of the pressure in the supply port 7 and the pressure in the load port 8, the flow rate from the load port 8 to the supply port 7 can be controlled by the opening degree of the variable throttle 6.

On the other hand, operate the direction control valve 27 to
is communicated with the pump 28 to make the internal pressure of the supply port 7 higher than the internal pressure of the load port 8, and when the variable throttle 6 is closed, the pressure of the oil passage 16 increases to the oil passage 13.
, the ball 22 of the shuttle valve moves to the right and seats on the seat 25. In this case as well, the poppet 4 is pushed only by the elastic force of the spring 20 without receiving any hydraulic pressure, and the poppet 4 is pressed against the seat 30.
The supply port 7 and the load port 8 are cut off from each other. Then, when the variable throttle 6 is opened, the oil in the supply port 7 flows through the first orifice 19 and the first
The supply port 7
The pressure inside becomes higher than the pressure inside the first chamber 23,
This pressure difference causes the poppet 4 to move to the spring 20.
The pressure oil from the supply port 7 flows into the load port 8. This flow rate is also proportional to the opening degree of the variable throttle 6, regardless of the internal pressure of the supply port 7 and the internal pressure of the load port 8.

Although the embodiments have been described in detail above, in the present invention, when the front seat surface of the poppet, which is urged toward the seat by a spring, is seated on the seat, communication between the supply port and the load port is cut off. In the logic valve, a first chamber communicating with the supply port via a first orifice and a second chamber communicating with the load port via a second orifice are formed behind the poppet, respectively. When the front seat surface of the poppet is seated on the seat, the pressure receiving area receiving the supply port pressure of this poppet is equal to the pressure receiving area receiving the first indoor pressure, and the pressure receiving area receiving the load port pressure is equal to the pressure receiving area receiving the above second indoor pressure. The pressure-receiving area receiving the indoor pressure is made equal, and a variable restriction is provided in the flow path of the fluid flowing out from the control port when either the first chamber or the second chamber communicates with the control port via the shuttle valve. Because of the interposition, the flow rate between the supply port and the load port can be controlled by the opening degree of the variable throttle without being affected by fluctuations in the supply port pressure and the load port pressure. Since either the first chamber or the second chamber is communicated with the control port via the shuttle valve, one variable throttle allows the flow from the supply port to the load port and from the load port to the supply port. Both flow rates can be controlled.

[Brief explanation of the drawing]

FIG. 1 is a schematic vertical cross-sectional view showing one embodiment of the present invention, and FIG. 2 is a schematic vertical cross-sectional view of a conventional logic valve. Spring...20, Seat...30, Poppet...4, Supply port...7, Load port...
8. First orifice...19. First chamber...2
3. Second orifice... 11. Second chamber...
9, Shuttle valve...21, 22, 24, 25, Control port...17, Variable throttle...6.

Claims (1)

[Claims] 1. When the front seat surface of the poppet, which is urged toward the seat surface by a spring, is seated on the seat, a supply port that communicates with the hydraulic pump or tank via the directional control valve and a load port that communicates with the actuator In the logic valve that blocks communication, behind the poppet, a first chamber communicates with the supply port via a first orifice, and a second chamber communicates with the load port via a second orifice. When the front seat surface of the poppet is seated on the seat, the pressure receiving area receiving the supply port pressure of the poppet and the pressure receiving area receiving the first indoor pressure are equal, and the pressure receiving area receives the load port pressure. A flow path where a pressure receiving area and a pressure receiving area receiving the second indoor pressure are made equal and flow out from the control port when either the first chamber or the second chamber communicates with the control port via the shuttle valve. A logic valve characterized by having a variable throttle installed in it.