JPH0381006B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides 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 FIG. 6, has an inflow path 1 connected to a fluid supply source P and an outflow path 2 connected to a storage tank T.
and a switching valve 5 for switching communication between the first and second load paths 3 and 4 connected to both oil chambers A1 and A2 of the actuator (hydraulic cylinder) A, respectively, and a switching valve 5 interposed in the second load path 4. It is composed of a first flow rate adjustment valve 6, a second flow rate adjustment valve 7, and a pilot type check valve 8.

In this flow rate control circuit, when the switching valve 5 is in the state shown in the figure, the oil chamber A is
2 to reservoir T is blocked and actuator A is held in the state shown. Further, when the inflow path 1 is connected to the second load path 4 and the outflow path 2 is connected to the first load path 3 by the switching valve 5, the flow rate supplied from the fluid supply source P to the oil chamber A2 becomes the first flow rate. The adjustment valve 6 throttles the operation of the actuator A to perform meter-in control. On the other hand, when the inflow path 1 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 oil chamber A2 is connected to the storage tank T.
The flow rate discharged is throttled by the second flow rate regulating valve 7, and the operation of the actuator A is controlled in a meter-out manner.

[Problem that the invention seeks to solve]

By the way, in the conventional meter-in/meter-out flow rate control circuit described above, its constituent members,
In other words, the switching valve 5, the first flow rate adjustment valve 6, the second flow rate adjustment valve 7, and the pilot type check valve 8 all control a large flow rate and are large, so the control circuit becomes large and requires installation space and space. There is a cost issue.

In addition, the flow rate adjustment by each flow rate adjustment valve 6, 7 is as follows.
Normally, this is done by manually rotating the adjustment screw that regulates the amount of movement of the valve body that throttles the large flow rate, which not only makes it difficult to work with, but also makes fine adjustments difficult because the large flow rate is directly adjusted. There is also a problem.

[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 part that forms a second oil chamber that communicates with the first oil chamber; and a connecting part that is connected to the connecting part and is slidably inserted into the one small diameter hole to form a third oil chamber at the end of the small diameter hole. A 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, and a throttle is provided in the first or second oil chamber at the end of the small diameter hole. a main valve comprising: a valve body integrally provided with a small diameter portion forming a fourth oil chamber connected through the main valve; and a spring urging the valve body toward the third oil chamber; a first pilot valve that proportionally controls the pilot pressure applied to the third oil chamber according to the current applied value; and a first pilot valve that cuts off communication between the fourth oil chamber and the return path when the pilot pressure is less than a set value; a second pilot valve that communicates the fourth oil chamber with the return path when the pilot pressure is equal to or higher than a set value; an inflow path connected to a fluid supply source; an outflow path connected to a storage tank; and an actuator. 1st
and a switching valve for switching communication between the load path and the second load path, 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 rate 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 If it is less than the set value, the second pilot valve switches to the fourth
Since the communication between the oil chamber and the return passage is cut off, the valve body of the main valve opens the poppet valve part 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 vehicle is seated on a 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 be equal to or higher than the set value, and the third oil chamber of the main valve is connected to the second load path. When the pilot pressure applied to the main valve 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 by the pilot pressure in the third oil chamber and the force of the spring are balanced and held.
Throttle the flow rate between channels. Therefore, if the first flow path and the second flow path are interposed in the second load path,
The flow rate supplied from the fluid supply source to the actuator through the second 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 be equal to or higher than the set value, so that the third oil chamber of the main valve is connected to the third oil chamber of the main valve. When the pilot pressure applied to the oil chamber becomes equal to or higher than the set value, the second pilot valve operates in the same manner as described above and communicates the fourth oil chamber with the return path, so the oil pressure in the fourth oil chamber becomes approximately zero. The valve body of the main valve is moved to a position where the pressing force due to the pilot pressure in the third 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 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. controlled.

Further, in the meter-in/meter-out flow rate control circuit according to the present invention, the meter-in/meter-out flow rate control circuit described above
During meter-out control, if you change the current applied to the first pilot valve (a value greater than the set value) and change the pilot pressure applied to the third oil chamber, you can adjust the position of the main valve's valve body. Therefore, it is possible to adjust the flow rate flowing through the load path in which the first flow path and the second flow path are interposed. 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 valve body of the main valve is not pushed due to fluctuations in the pressure within the flow path and the second flow path.

〔Effect of the invention〕

The meter-in/meter-out flow rate control circuit according to the present invention includes a main valve and a switching valve that control a large flow rate,
Since the first and second pilot valves that control small flow rates are used as its constituent members, it can be made much smaller than the conventional flow rate control circuit shown in Figure 6, reducing installation space. and cost reduction.

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 flow path is adjusted by fluctuations in the pressure in the load path. The valve body of the valve 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, the flow rate can be easily finely adjusted, and 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 rate control circuit according to the present invention, which includes a main valve 10, a first pilot valve 20, a second pilot valve 30, a third pilot valve 40, and a solenoid switching valve 50. It is composed of.

As shown in FIGS. 1 and 2, the main valve 10 includes a valve body 11 consisting of a first member 11A, a second member 11B, and a third member 11C;
The valve body 12 is slidably inserted in the inner hole in the axial direction.
and a spring 13 that urges this valve body 12 to the left in the figure.
It is composed of. The valve body 11 has small diameter holes 11b, 11 of the same diameter at both left and right ends of the large diameter hole 11a.
It has a stepped inner hole with a valve seat 11d formed in the left continuous stepped part, and an annular groove 11e with which the first flow path P1 communicates, and a second
It has an annular groove 11f with which the 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 P1), and is inserted into both oil chambers.
A poppet valve part 12a forms Ro, R1 and seats on or leaves the valve seat 11d to cut off communication (open/close) between both flow paths P1 and P2, and a poppet valve part 12a is connected to the left side of the poppet valve part 12a and is connected to the left side. A connecting portion 12b that extends into the small diameter hole 11b and forms an oil chamber R2 with which the second flow path P2 is always in communication with the small diameter hole 11b, and a small diameter hole 11b on the left that is connected to the small diameter hole 11b. A piston part 12c is integrally fitted into the small diameter hole 11b to form an oil chamber R3 at the end of the small diameter hole 11b.
It is integrally provided with a small diameter cylindrical portion 12d that is slidably inserted into the small diameter hole 11c and forms an oil chamber R4 at the end of the small diameter hole 11c. Thus, the oil chamber Ro is connected to the first passage P1 via the throttle 14 and also to the third pilot valve 40, and the oil chamber R1 is connected to the lower chamber A2 of the hydraulic cylinder A through the first passage P1. The oil chamber R2 is connected to the electromagnetic switching valve 50 through the second flow path P2. Further, the oil chamber R3 is connected to the first pilot valve 20 and the second pilot valve 3.
The oil chamber R4 is connected to the oil chamber R1 through the throttle 15, and the second pilot valve 30 and the third pilot valve 40 are connected to It is connected to the.

The first pilot valve 20 is a pressure reducing valve 21 that reduces the pressure of the pressure oil introduced through the inflow path Pp to a predetermined value.
The pressure reducing valve 21 passes through the throttle 22 to the oil chamber R.
The current control relief valve 23 proportionally controls the pilot pressure applied to the valve 3 in accordance with the current applied value. The second pilot valve 30
As shown in FIG. 3 and FIG. 3, the first
It is composed of a switching valve 31 and a second switching valve 32 whose operation is controlled by the first switching valve 31. The first switching valve 31 includes a spool valve body 31a and a spring 31b, and has an oil chamber R3 to an oil chamber R5.
When the pilot pressure applied through the passage P3 is less than the set value, the inflow passage Pp and the second switching valve 32 are disconnected from each other in the non-operating state as shown in the figure.
Further, when the pilot pressure is equal to or higher than a set value, the valve is activated and connects the inflow passage Pp to the second switching valve 32. The second switching valve 32 includes a piston 32a integrally having a protrusion, a poppet valve body 32b, and a spring 3.
2c, which operates when the oil chamber R6 is connected to the inflow path Pp by the first switching valve 31, and connects the passage P4 communicating with the oil chamber R4 and the return passage P5 communicating with the storage tank T; Further, when the oil chamber R6 is disconnected from the inflow path Pp and connected to the return path P5 by the first switching valve 31, it becomes inoperable as shown in the figure, and the passage P4 communicating with the oil chamber R4 and the return The communication of path P5 is cut off.

The third pilot valve 40 operates when the hydraulic pressure in the first flow path P1 applied through the throttle 14 exceeds a set value, and returns the hydraulic oil in the oil chamber Ro to the return path P1.
5 and a switching valve 42 that operates in response to the operation of the relief valve 41. As shown in FIGS. 1 and 4, the switching valve 42 includes a valve body 42a and a spring 42b, and the hydraulic pressure in the first passage P1 applied to the oil chamber R7 through the passage P6 is relieved. When it is not relieved by the valve 41, it is in a non-operating state as shown in the figure, and the connection between the oil chamber R8 communicating with the oil chamber R4 and the return path P5 is cut off, and the oil pressure applied to the oil chamber R7 is applied to the relief valve. 41, the valve body 42a slides against the spring 42b due to the hydraulic pressure in the first flow path P1 applied to the oil chamber R9 through the passage P7, and the oil chamber R8 returns to the oil chamber R9 through the return path P5. Connect to.

The electromagnetic switching valve 50 has an inflow path Pp connected to the fluid supply source P, an outflow path Pt connected to the storage tank T, a first load path Pa connected to the upper oil chamber A1 of the hydraulic cylinder A, and a first load path Pa connected to the upper oil chamber A1 of the hydraulic cylinder A. This is a switching valve that is connected to the lower oil chamber A2 and switches the communication of the second load path Pb, which is formed by interposing the first flow path P1 and the second flow path P2 of the main valve 10 described above. Paths Pa and Pb are cut off from the inflow path Pp and communicated with the outflow path Pt. In this electromagnetic switching valve 50, when the solenoid 51 is energized, the inflow path Pp is connected to the second load path Pb, and the outflow path Pt is connected to the first load path Pa, and 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 inflow path Pp is connected to both load paths Pa and Pp by the electromagnetic switching valve 50.
Pb is blocked and the first pilot valve 2
If the value of current applied to the current control relief valve 23 of No. 0 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, the dual switching valve 31 of the second pilot valve 30 , 32 are not operating and the communication between the oil chamber R4 of the main valve 10 and the return path P5 is cut off.
and oil chamber R4 from the first oil chamber R1 through the throttle 15.
The poppet valve portion 12a is pressed to the left in the figure by the hydraulic pressure applied to the valve seat 1 and the acting force of the spring 13.
1d, and the second load path Pb is the main valve 1.
Blocked by 0. Therefore, the main valve 10
The oil pressure in the circuit from the lower oil chamber A2 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, causing the oil pressure in the lower oil chamber A2 to rise, and the oil pressure in the first flow path P1 to exceed the value set by the relief valve 41 of the third pilot valve 40. Then, the pressure oil in the oil passage P6 flows to the return passage P5 and the switching valve 42 is activated, and the pressure oil in the oil chamber R4 of the main valve 10 flows to the return passage P5 through the switching valve 42.
Therefore, in such a case, the oil chamber R3 of the main valve 10
The main valve 12 is pushed against the spring 13 by the hydraulic pressure inside, and the first flow path P1 and the second flow path P2 communicate with each other.
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.

Also, by energizing the solenoid 51, the electromagnetic switching valve 50 is actuated to change the inflow path Pp to the second load path Pb.
In addition, the outflow path Pt is connected to the first load path Pa, and the current applied to the current control relief valve 23 of the first pilot valve 20 is set to be equal to or higher than the set value, and the pilot is applied to the oil chamber R3 of the main valve 10. When the pressure exceeds the set value, both switching valves 31 and 32 of the second pilot valve 30 operate to communicate the oil chamber R4 of the main valve 10 with the return path P5, so the oil pressure in the oil chamber R4 becomes approximately zero. , the valve body 12 of the main valve 10 is moved 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 and held, and the first flow path P
The flow rate flowing between the flow path P1 and the second flow path P2 is reduced. Therefore, the flow rate supplied from the fluid supply source P to the lower oil chamber A2 of the hydraulic cylinder A 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 actuated to change the inflow path Pp to the first load path Pa.
In addition, the outflow path Pt is connected to the second load path Pb, and the current applied to the current control relief valve 23 of the first pilot valve 20 is set to be equal to or higher than the set value, and the pilot is applied to the oil chamber R3 of the main valve 10. When the pressure exceeds the set value, the switching valves 31 and 32 of the second pilot valve 30 operate in the same manner as described above to communicate the oil chamber R4 of the main valve 10 with the return path P5.
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, and is held there. The flow rate flowing between the second flow paths P2 is throttled. Therefore, the flow rate discharged from the lower oil chamber A2 of the hydraulic cylinder A to the storage tank T through the second load path Pb is throttled, and the operation of the hydraulic cylinder A is controlled to be metered out.

In addition, in the meter-in/meter-out flow rate control circuit of this embodiment, during the meter-in/meter-out control described above, the first pilot valve 2
If the pilot pressure applied to the oil chamber R3 is changed by changing the value of current applied to the current control relief valve 23 (however, a value greater than the set value), the valve body 1 of the main valve 10
2 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 meter-in/meter-out control described above, the first valve acting on the valve body 12 of the main valve 10
Since the pressures in the flow path P1 and the second flow path P2 are always offset, the main valve The ten valve bodies 12 are never 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 a large flow rate, and the first, second, and third valves that control a small flow rate. Pilot valve 2
Since its constituent members are 0, 30, and 40,
Compared to the conventional flow rate control circuit shown in FIG. 6, the size can be significantly reduced, and installation space and costs can be reduced.

Furthermore, in the meter-in/meter-out flow rate control circuit of this embodiment, the pressures in the first and second flow paths P1 and P2 acting on the valve body 12 of the main valve 10 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, the first pilot valve 20
By determining the value of current applied to the current control relief valve 23, the position of the valve body 12 of the main valve 10 can be accurately set, the flow rate flowing through the second load path Pb can be adjusted, and the flow rate can be easily fine-tuned. In addition to being able to adjust the flow rate, it is also possible to improve the workability of adjusting the flow rate.

[Modified example]

In the above embodiment, the first flow path P of the main valve 10
1 is connected to the lower oil chamber A2 of the hydraulic cylinder A, and the second flow path P2 is connected to the electromagnetic switching valve 50, and a throttle 15 is interposed in the passage connecting the oil chamber R1 and the oil chamber R4. Although the invention was carried out, as shown in FIG. At the same time, valve body 1
It is also possible to implement the present invention by interposing a throttle 15 in the passage that communicates the oil chambers R1 and R2 provided in the oil chambers R1 and R2. In this case, the oil pressure in the oil chamber R2 is applied to the oil chamber R4 through the throttle 15, and the same operation as in the above embodiment is obtained.

Further, as shown in FIG. 5, the present invention does not employ the third pilot valve 40 of the above embodiment, and instead of the first pilot valve 20, a current-controlled pressure reducing valve is used. Adopts the first pilot valve 20A which has the same function as 20,
Further, in place of the second pilot valve 30, there is provided a switching valve which is operated directly by pilot pressure to disconnect communication between the oil chamber R4 and the return path P5.
2nd pilot valve 30A having the same function as 0
It is also possible to adopt and implement this. Note that if the third pilot valve 40 is not adopted, the throttle 1
4 is no longer necessary, so as shown in Figure 5,
It is also possible to combine the oil chamber Ro of the above embodiment with the oil chamber R1.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the 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. FIG. 4 is a detailed enlarged sectional view of the second pilot valve portion in the circuit shown in FIG. 1, FIG. 4 is a detailed enlarged sectional view of the third pilot valve portion in the circuit shown in FIG. FIG. 6 is an overall configuration diagram showing another embodiment of a flow 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,
11a...Large diameter hole, 11b, 11c...Small diameter hole,
11d... 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 pilot valve, 30... Second pilot valve, 50... Solenoid switching valve, P1...
First channel, P2... second channel, Pp... inflow channel,
P5... Return path, Pt... Outflow path, Pa... First load path, Pb... Second load path, Ro, R1... (first) oil chamber, R2... (second) oil chamber, R3... (third) oil chamber, R4... (fourth) oil chamber, P... fluid supply source, T... storage tank, A... hydraulic cylinder (actuator).

Claims (1)

[Scope of Claims] 1. A valve body having small diameter holes of the same diameter connected to both ends of a large diameter hole, and a valve seat formed in one of the connected steps, and a A poppet valve part that is inserted in a balanced state 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 second oil chamber is connected to one side, extends into the one small diameter hole, and is in communication with the second flow path at all times and communicates with the first oil chamber through the valve seat. A connecting part 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 are integrally provided, and the poppet valve part and other parts are integrally provided. a small diameter portion that is connected to the side and is slidably inserted into the other small diameter hole and forms a fourth oil chamber that is connected to the first or second oil chamber via a throttle at the end of the small diameter hole; A main valve including a valve body integrally provided, a spring that urges the valve body toward the third oil chamber, and a pilot pressure applied to the third oil chamber according to a current applied value. a first pilot valve that proportionally controls the first pilot valve; and a first pilot valve that cuts off communication between the fourth oil chamber and the return path when the pilot pressure is less than a set value, and that connects the fourth oil chamber and the return passage when the pilot pressure is equal to or higher than the set value. a second pilot valve that communicates the return path; an inflow path connected to a fluid supply source; an outflow path connected to a storage tank; and a first pilot valve connected to an actuator.
A meter-in/meter-out flow rate control circuit, comprising: a switching valve that switches communication between the load path and the second load path, and the first flow path and the second flow path are interposed in either one of the load paths.