JPS62194005A - Meter-in, meter-out flow-rate control circuit - Google Patents

Abstract

PURPOSE:To make the captioned circuit compact, by forming the circuit with a main valve and a switching valve, both of which are used to control the large flow-rate, in addition to the first and second pilot valves, both of which are used to control the small flow-rate. CONSTITUTION:A meter-in, meter-out flow-rate control circuit is made up of a main valve 10, the first pilot valve 20, the second pilot valve 30, the third pilot valve 40, and an electromagnetic switching valve 50. If the pilot pressure given to an oil chamber R3 is changed by varying the current value to a relief valve in the first pilot valve 20, the position of a valve body 12 of the main valve 10 can be adjusted, or the flow-rate can be controlled. With this contrivance, the circuit can sharply be miniaturized.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to meter-in/meter-out flow rate control in which a fluid supply source and a storage tank are connected to an actuator to separately control one-way operation and other-direction operation of the actuator. Regarding circuits.

(Prior art) The conventional meter-in/meter-out flow rate control circuit
As shown in the figure, an inflow path 1 connected to a fluid supply source P, an outflow path 2 connected to a storage tank T, and an actuator (
Hydraulic cylinder) A's both chambers A1. A switching valve 5 that switches communication between the first and second load paths 3.4 connected to A2, respectively, and a first flow rate regulating valve 6.4 interposed in the second fi load path 4.
It is composed of a second flow control valve 7 and a pilot type check valve 8.

In this flow rate control circuit, when the switching valve 5 is in the illustrated state, the flow from the oil chamber A2 to the storage tank T is blocked by the action of the check valve 8, and the actuator A is maintained in the illustrated state. In addition, the switching valve 5 allows the inflow path 1 to be connected to the second load path 4.
In addition, when the outflow path 2 is connected to the first load path 3, the flow rate supplied from the fluid supply source P to the oil chamber 2 is throttled by the first flow rate regulating valve 6, and the operation of the actuator A is controlled by meter-in control. be done. On the other hand, when the inflow path I is connected to the first load path 3 and the outflow path 2 is connected to the second load path 4 by the switching valve 5, the flow rate discharged from the oil chamber A2 to the storage tank 'r is adjusted by the second flow rate adjustment. The valve 7 throttles the operation of the actuator A to perform meter-out control.

[Problem that the invention seeks to solve]

By the way, in the above-described conventional meter-in/meter-out flow rate control circuit, its constituent members, namely the switching valve 5. First flow rate regulating valve6. Since the second flow rate regulating valve 7 and the pilot type check valve 8 are all large in size and control a large flow rate, the control circuit becomes large, which poses problems in terms of installation space and cost.

In addition, the flow rate adjustment using each flow rate adjustment valve 6.7 is usually done by manually rotating the adjustment screw that regulates the amount of movement of the valve body that throttles the large flow rate. Since the flow rate is directly adjusted, there is also the problem that fine adjustment is difficult.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention provides a meter-in/meter-out flow rate control circuit in which small diameter holes of the same diameter are connected to both ends of a large diameter hole, and a valve seat is installed in one of the connected steps. The valve body is fitted into the large-diameter hole in a pressure-balanced state to form a first oil chamber that is constantly in communication with the first flow path, and is seated on or removed from the valve seat. A poppet valve part that opens and closes the valve seat is connected to one side of the poppet valve part, extends into the small diameter hole of the one, and is in constant communication with the second flow path between the small diameter hole and the valve seat. A connecting portion that forms a second oil chamber that communicates with the first oil chamber; and a connecting portion that is connected to the connecting portion and is slidably inserted into the one small diameter hole to form a third oil chamber at the end of the small diameter hole. The first or second piston is integrally provided with a piston part that is connected to the other side of the poppet valve part and is slidably inserted into the other small diameter hole.
A main body comprising: a valve body integrally provided with a small diameter portion forming a fourth oil chamber connected to the oil chamber via a throttle; and a spring urging the valve body toward the third oil chamber. a first viroft valve that proportionally controls pilot pressure applied to the third oil chamber according to a current applied value; and communication between the fourth oil chamber and a return path when the pilot pressure is less than a set value. a second pyro 7 which interrupts the flow and communicates the fourth oil chamber with the return path when the pilot pressure is equal to or higher than a set value;
) a valve, an inflow passageway connected to a fluid supply source, an outflow passageway connected to a reservoir, and first and second valves connected to an actuator;
A switching valve is provided for switching communication between the load paths, and the first flow path and the second flow path are interposed in either one of the load paths.

[Action of the invention]

In the meter-in/meter-out flow control circuit according to the present invention, the inflow path is cut off from both load paths by the switching valve, and the current applied to the first pilot valve is less than the set value, and the pilot pressure is set to the set value. If it is less than the second
Since the pilot valve blocks communication between the fourth oil chamber and the return passage, the valve body of the main valve is moved by the hydraulic pressure applied to the fourth oil chamber from the first or second flow passage through the throttle and the acting force of the spring. The Pobesoto valve portion is seated on the valve seat, and the second load path is blocked by the main valve. Therefore, the oil pressure in the circuit from the main valve to the actuator is maintained, and the actuator is maintained in its stopped state.

In addition, the inflow path is connected to the second load path and the outflow path is connected to the first load path by the switching valve, and the current applied to the first pilot valve is set to a set value or more and is applied to the third oil chamber of the main valve. When the pilot pressure exceeds the set value, the second pilot valve operates and communicates the fourth oil chamber with the return path, so the oil pressure in the fourth oil chamber becomes almost zero, and the valve body of the main valve
It is moved to a position where the pressing force due to the pilot pressure in the oil chamber and the force of the spring are balanced and held, thereby restricting the flow rate between the first flow path and the second flow path. Therefore, if the first flow path and the second flow path are interposed in the second load path, the second flow path is connected to the second load path from the fluid supply source.
The flow rate supplied to the actuator through the load path is throttled to perform meter-in control of the actuator operation.

On the other hand, the inflow path is connected to the first load path and the outflow path is connected to the second load path by the switching valve, and the current applied to the first pilot valve is set to a set value or higher and applied to the third oil chamber of the main valve. When the pyro 7) pressure exceeds the set value, the second pilot valve operates in the same way as described above and communicates the fourth oil chamber with the return path, so the oil pressure in the fourth oil chamber is approximately The valve body of the main valve is moved to a position where the pressing force due to the pilot pressure in the third chamber and the force of the spring are balanced and held, thereby throttling the flow rate between the first flow path and the second flow path.

Therefore, if the first flow path and the second flow path are interposed in the second load path, the flow rate discharged from the actuator to the storage tank through the second load path is throttled, and the operation of the actuator is metered out; ν controlled.

Furthermore, in the meter-in/meter-out flow rate control circuit according to the present invention, during the above-described meter-in/meter-out control, the current applied to the first pilot valve (however, a value greater than or equal to the set value) is changed to By changing the pilot pressure applied to the main valve, the position of the valve body of the main valve can be adjusted.
The flow rate flowing through the load path in which the first flow path and the second flow path are interposed can be adjusted. In this case, of course, even during the above-mentioned meter-in/meter-out control, the pressures in the first flow path and the second flow path acting on the valve body of the main valve are always offset, so that the pressure in the first flow path Also, the valve body of the main valve is not pushed due to fluctuations in the pressure within the second flow path.

〔Effect of the invention〕

The meter-in/meter-out flow rate control circuit according to the present invention has a main valve and a switching valve that control a large flow rate, and first and second pilot valves that control a small flow rate as its constituent members. Compared to conventional flow rate control circuits, it can be made much more compact, reducing installation space and cost.

Furthermore, in the meter-in/meter-out flow rate control circuit according to the present invention, the pressures in the first and second flow paths acting on the valve body of the main valve are always canceled out, and the pressure in the main valve changes due to fluctuations in the pressure in the load path. The valve body is not pushed. Therefore, by determining the value of current applied to the first pilot valve, the position of the valve body of the main valve can be set accurately, the flow rate flowing through the load path can be adjusted, and the flow rate can be easily finely adjusted. At the same time, the workability of adjusting the flow rate can be improved.

〔Example〕

An embodiment of the present invention will be described below based on the drawings.

FIG. 1 shows a meter-in/meter-out flow control circuit according to the present invention, which includes the main valve 10. 1st
Viloft valve 20. Second pilot valve 30. It is composed of a third pilot valve 40 and an electromagnetic switching valve 50.

As shown in FIGS. 1 and 2, the main valve 10 has a first
A valve body 11 consisting of a member 11A, a second member 11B, and a third member 11G, a valve body 12 fitted into an inner hole of this valve body 11 so as to be slidable in the axial direction, and this valve body 12 shown on the left in the figure. It is constituted by a spring 13 that biases it in the direction. Valve body 1
1 is a small diameter hole 11b having the same diameter at both left and right ends of a large diameter hole 11a.
, 11C, respectively, and has a stepped inner hole in which a valve seat lid is formed in the left continuous step part, and
It has an annular groove lie through which the flow path P1 communicates and an annular rizr through which the second flow path P2 communicates.

The valve body 12 is slidably inserted into the large-diameter hole 11a in a pressure-balanced state (with both left and right ends receiving pressure in the first flow path Pl), and opens both chambers Ro and R1. A poppet valve part 12a is formed and seats on or leaves the valve seat lid to block communication (open/close) between the flow paths PI and P2, and a left small diameter hole 11b is connected to the left side of the poppet valve part 12a. A connecting portion 12b that extends inward and forms an oil chamber R2 between which a second flow path P2 is always in communication with the small diameter hole 11b, and a connecting portion 12b that is connected to the connecting portion 12b and can freely slide into the left small diameter hole 11b. A piston portion 12c is fitted into the small diameter hole 11b and forms an oil chamber R3 at the end of the small diameter hole 11b.
The small diameter hole 11c is slidably inserted into the right small diameter hole 11c on the right side of the poppet valve portion 12a.
A small diameter cylindrical portion 12d forming an oil chamber R4 is integrally provided at the 1c end. Thus, the oil chamber Ro is connected to the first flow path P1 via the throttle 14, and the third pilot valve 40
The oil chamber R1 is connected to the lower chamber A2 to the hydraulic cylinder through the first flow path P1, and the oil chamber R2 is connected to the second flow path P2.
It is connected to the electromagnetic switching valve 50 through. Also oil room R
3 is connected to the first pilot valve 20 and the first switching valve 31 of the second pilot valve 30, and the oil chamber R4
is connected to the oil chamber R1 via the throttle 15, and is also connected to the second switching valve 32 of the second pilot valve 30 and the switching valve 42 of the third pilot valve 40.

The first pilot valve 20 includes a pressure reducing valve 21 that reduces the pressure of the pressure oil introduced through the inflow path Pp to a predetermined value, and this pressure reducing valve 2
The current control relief valve 23 proportionally controls the pilot pressure applied from 1 to the oil chamber R3 through the throttle 22 in accordance with the current applied value. 2nd pilot valve 3
0, as shown in FIGS. 1 and 3, includes a first switching valve 31 whose operation is controlled by pilot pressure applied to the oil chamber R3, and a valve whose operation is controlled by this first switching valve 31. It is configured by a second switching valve 32.

The first switching valve 31 includes a spool valve body 31a and a spring 31b, and is in an inoperable state as shown in the figure when the pilot pressure applied from the oil chamber R3 to the oil chamber R5 through the passage P3 is less than a set value. The inflow path Pp and the second switching valve 32
When the pilot pressure is equal to or higher than the set value, the valve is activated to connect the inflow passage pp to the second switching valve 32.

The second switching valve 32 includes a piston 32 that integrally has a protrusion.
a, comprising a poppet valve body 32b and a spring 32c,
A passage P4 and a storage tank T that are activated when the oil chamber R6 is connected to the inflow passage pp by the first switching valve 31 and communicate with the oil chamber R4.
The return path P5 is connected to the first switching valve 31.
When the oil chamber 1)6 is disconnected from the inflow path Pp and connected to the return path P5, it becomes inoperable as shown in the figure and communicates with the oil chamber R4. cut off.

The third pilot valve 40 is a relief valve 41 that operates when the oil pressure in the first flow path Pl applied through the throttle 14 exceeds a set value and causes the hydraulic oil in the oil chamber RO to flow to the return path 1)5. and a switching valve 42 that operates in response to the operation of the relief valve 41. The switching valve 42 is a first
As shown in the figure and FIG. 4, the valve body 42a and the spring 42
b, and when the oil pressure in the first flow path P1 applied to the oil chamber R7 through the passage P6 is not relieved by the relief valve 41, it is in a non-operating state as shown in the figure and communicates with the oil chamber R4. When the oil chamber R8 and the return path P5 are disconnected, and the oil pressure applied to the oil chamber R7 is relieved by the relief valve 41, the oil pressure in the first passage Pi is applied to the oil chamber R9 through the passage P7. The valve body 42a slides against the spring 42b to connect the oil chamber R8 to the return path P5.

The electromagnetic switching valve 50 has an inflow path P connected to a fluid supply source P.
p and an outflow passage P connected to a storage tank T [and a hydraulic cylinder A
A second load path Pa connected to the upper oil chamber A1 of the hydraulic cylinder A and a second flow path connected to the lower oil chamber A2 of the hydraulic cylinder A with the first flow path PT and the second flow path P2 of the main valve 10 mentioned above interposed therebetween. This is a switching valve that switches communication of the load path pb, and in the neutral state shown in the figure, cuts off both load paths Pa and Pb from the inflow path Pp and connects the outflow path Pt.
communicate with. In this electromagnetic switching valve 50, by energizing the solenoid 51, the inflow path Pp is connected to the second load path Pb, and the outflow path I)t is connected to the first load path Pb.
When the solenoid 52 is energized, the inflow path Pp is connected to the first load path Pa, and the outflow path pt is connected to the second load path Pb.

In this embodiment configured as described above, the electromagnetic switching valve 50 allows the inflow path Pp to be connected to both load paths Pa.

If the current applied to the current control relief valve 23 of the first pilot valve 20 is less than the set value and the pilot pressure applied to the oil chamber R3 of the main valve 10 is less than the set value. For example, the dual switching valve 3 of the second pilot valve 30
1.32 does not operate, and the communication between the oil chamber R4 of the main valve 10 and the return path P5 is cut off, and the applied hydraulic pressure and the acting force of the spring 13 push the povent valve portion 12a to the left in the figure.
d, and the second load path pb is blocked by the main valve 10. Therefore, the oil pressure in the circuit from the main valve 10 to the lower oil chamber A2 of the hydraulic cylinder A is maintained, and the hydraulic cylinder A is maintained in its stopped state. In this case, an excessive load acts on the hydraulic cylinder A, the oil pressure in the lower oil chamber A2 increases, and the oil pressure in the first flow path Pl increases.
When the value exceeds the value set by the relief valve 41 of the pilot valve 40, the pressure oil in the oil passage P6 flows to the return passage P5, the switching valve 42 is activated, and the pressure oil in the oil chamber R4 of the main valve IO is switched. It flows through the valve 42 to the return path P5. Therefore, in such a case, the main valve 12 is pushed against the spring 13 by the oil pressure in the oil chamber R3 of the main valve 10, and the first flow path PI and the second flow path P
2 is connected. Therefore, pressure oil flows from the lower oil chamber A2 of the hydraulic cylinder A to the storage tank T, and the hydraulic cylinder A is protected.

In addition, by energizing the solenoid 51, the electromagnetic switching valve 50
to connect the inflow path pp to the second load path Pb and the outflow path Pt to the first load path pa, and set the current applied value to the current control relief valve 23 of the first pilot valve 20 to be equal to or higher than the set value. When the pilot pressure applied to the oil chamber R3 of the main valve 10 exceeds the set value, the second pilot valve 3
Both switching valves 31 and 32 of the main valve 10 operate and the oil chamber R4 of the main valve 10 is activated.
In order to connect the return valve to VRP5, the oil pressure in the oil chamber R4 becomes approximately zero, and the valve body 12 of the main valve 10 moves to a position where the pressing force due to the pilot pressure in the oil chamber R3 and the force of the spring 13 are balanced. The flow rate that is held and flows between the first flow path P1 and the second flow path P2 is throttled. Therefore, the flow rate supplied from the fluid supply source P to the lower oil chamber A2 to the hydraulic cylinder through the second load path Pb is throttled, and the operation of the hydraulic cylinder A is meter-in controlled.

On the other hand, by energizing the solenoid 52, the electromagnetic switching valve 50
is operated to connect the inflow path Pp to the first load path Pa and the outflow path PT to the second load path pb, and also set the current applied value to the current control relief valve 23 of the first pilot valve 20 to be equal to or higher than the set value. When the pilot pressure applied to the oil chamber R3 of the main valve 10 becomes equal to or higher than the set value, the both switching valves 31 and 32 of the second pilot valve 30 are operated in the same way as described above, and the oil chamber R4 of the main valve 10 is activated. In order to communicate with the return path P5, the oil pressure in the oil chamber R4 becomes almost zero, and the valve body 12 of the main valve 1O reaches a position where the pressing force due to the pyro pressure in the oil chamber R3 and the force of the spring 13 are balanced. The first flow path P1 is moved and held.
and the second flow path P2. Therefore, the flow rate discharged from the lower oil chamber A2 of the hydraulic cylinder A to the storage tank 'r through the second load path pb is throttled and the hydraulic cylinder A
operation is meter-out controlled.

In addition, in the meter-in/meter-out flow rate control circuit of this embodiment, during the above-described meter-in/meter-out control, the current applied value to the current control relief valve 23 of the first pilot valve 20 (however, a value greater than or equal to the set value) ) by changing the pilot pressure applied to the oil chamber R3, the position of the valve body 12 of the main valve 10 can be adjusted, and the flow rate flowing through the second load path pb can be adjusted. In this case, of course, even during the above-mentioned meter-in/meter-out control, the pressures in the first flow path P1 and the second flow path P2 acting on the valve body 12 of the main valve 10 are always canceled out, so that The pressure inside the first flow path PI and the second flow path P2 (i.e., the pressure inside the second flow path P2 is
The valve body 12 of the main valve 10 due to fluctuations in the pressure inside the load passage pb
will not be pushed.

As is clear from the above description, the meter-in/meter-out flow rate control circuit of this embodiment includes the main valve 10 and the electromagnetic switching valve 50 that control one large flow rate, and the first one that controls a small flow rate.
Since the second and third pilot valves 20, 30, and 40 are used as its constituent members, it can be made much smaller than the conventional flow control circuit shown in Fig. 6, reducing installation space. and cost reduction.

Furthermore, in the meter-in/meter-out flow rate control circuit of this embodiment, the pressures in the first and second flow paths Pi and R2 acting on the valve body 12 of the main valve IO are always offset, and the pressures in the second load path The valve body 12 of the main valve 10 is not pushed due to fluctuations in the Pb internal pressure. Therefore, by determining the current applied value to the current-controlled relief valve 23 of the first pilot valve 20, the position of the valve body 12 of the main valve 10 can be accurately set, and the flow rate flowing through the second load path pb can be adjusted. , the flow rate can be easily fine-tuned, and
The workability of flow rate adjustment can be improved.

[Modified example]

In the above embodiment, the first flow path P1 of the main valve 10 is connected to the lower oil chamber A2 of the hydraulic cylinder A, the second flow path P2 is connected to the electromagnetic switching valve 50, and the oil chamber R1 and the oil chamber R
The present invention was implemented by interposing a throttle 15 in the passage connecting the main valve IOA, but as shown in FIG. 2 flow path P2 is connected to the lower oil chamber Δ2 of the hydraulic cylinder A, and the valve body 1 is connected to the lower oil chamber Δ2 of the hydraulic cylinder A.
A throttle 1 is installed in the passage connecting the oil chambers R1 and R2 provided in 2.
It is also possible to implement the present invention by interposing 5. In this case, the oil pressure in the oil chamber R2 passes through the throttle 15 to the oil chamber R2.
4 to obtain the same operation as the above-described embodiment.

Further, as shown in FIG. 5, the present invention does not employ the third pilot valve 40 of the above embodiment, and the first
The first valve consists of a current-controlled pressure reducing valve instead of the pilot valve 20.
A first pilot valve 20A having the same function as the pilot valve 20 is adopted, and in place of the second pilot valve 30, a switching valve that is directly operated by pilot pressure and disconnects communication between the oil chamber R4 and the return path 25 is used. It is also possible to employ and implement the second pilot valve 30A having the same function as the second pilot valve 30. Note that if the third pilot valve 40 is not adopted, the throttle 14 is not necessary, so it is also possible to combine the oil chamber Ro of the above embodiment with the oil chamber R1, as shown in FIG. .

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram showing one embodiment of a meter-in/meter-out flow rate control circuit according to the present invention, FIG. 2 is a detailed enlarged sectional view of the main valve portion of the circuit shown in FIG. 1, and FIG.
The figure is a detailed enlarged sectional view of the second pilot valve part in the circuit shown in Fig. 1, FIG. 4 is a detailed enlarged sectional view of the third pilot valve part in the circuit shown in Fig. 1, and
FIG. 6 is an overall configuration diagram showing another embodiment of the flow rate control circuit according to the present invention, and FIG. 6 is an overall configuration diagram showing a conventional example. Explanation of symbols 10...Main valve, 11...Valve body, lla...Large diameter hole, llb, IIC...Small diameter hole, lid...Valve seat,
12... Valve body, 12a... Poppet valve part, 12b.
...Connection part, 12C... Piston part, 12d... Small diameter part, 13... Spring, 15... Throttle, 20... First viroft valve, 30... Second pilot valve, 50・
...Solenoid switching valve, Pi...first flow path, R2...second
Flow path, Pp...Inflow path, R5...Return path, pt...
・Outflow path, Pa...first load path, pb...second load path, Ro, R1... (first) oil chamber, R2... (
2nd) oil chamber, R3... (3rd) oil chamber, R4...
(4th) Oil chamber, P...Fluid supply source, T...Storage tank, A
...Hydraulic cylinder (actuator). Outsourcing company fi Kogyo Co., Ltd.

Claims (1)

[Scope of Claims] A valve body having a large diameter hole with small diameter holes of the same diameter connected to each other at both ends, and a valve seat formed in one of the continuous steps, and a pressure balance within the large diameter hole. a poppet valve part that is inserted into the valve seat to form a first oil chamber that is always in communication with the first flow path, and that opens and closes the valve seat by seating on and leaving the valve seat; a connection that is connected to the side and extends into the one small-diameter hole, and forms a second oil chamber between the small-diameter hole and the second oil chamber that constantly communicates with the second flow path and communicates with the first oil chamber through the valve seat; and a piston part connected to the connecting part and slidably inserted into the one small-diameter hole to form a third oil chamber at the end of the small-diameter hole, and the other side of the poppet valve part. A fourth oil chamber is connected to the other small diameter hole, is slidably inserted into the other small diameter hole, and is connected to the first or second oil chamber via a throttle at the end of the small diameter hole.
a main valve provided with a valve body integrally having a small diameter portion forming an oil chamber, and a spring that urges the valve body toward the third oil chamber; a first pilot valve that proportionally controls pilot pressure according to a current applied value; and a first pilot valve that cuts off communication between the fourth oil chamber and a return path when the pilot pressure is less than a set value, and when the pilot pressure is equal to or higher than the set value. a second pilot valve that communicates the fourth oil chamber with the return path; an inflow path connected to a fluid supply source; an outflow path connected to a storage tank; and first and second pilot valves connected to an actuator.
A meter-in/meter-out flow rate control circuit, comprising a switching valve for switching communication between load paths, wherein the first flow path and the second flow path are interposed in either one of the load paths.