JPH06229402A - Flow rate direction control valve device - Google Patents

Abstract

PURPOSE:To carry out controlled flow action in a check valve provided in an output passage of a flow rate direction control valve device for decreasing a leaking quantity. CONSTITUTION:A normally closed pilot operational type opening/closing valve 34 placed in its opening operation in response to pressure variation of pilot chambers 13,14 by which a main valve spool is moved so that an output passage 11 in which a check valve 12 is provided may be communicated with return passage is installed in a drain passage from the back chamber 12D of the check valve 12, and controlled flow action in the check valve 12 is secured owing to opening operation of the opening/closing valve 34.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention moves a main valve spool, which is biased to a neutral position by a spring, to one or the other from the neutral position according to a pressure difference in a pilot chamber and supplies the main valve spool at the neutral position. The output path, which is cut off from the path and the return path, is connected to the supply path by the movement from the neutral position of the main valve spool to one side, and to the return path by the movement to the other side.
The present invention relates to a flow direction control valve device that controls the operating direction and operating speed of a hydraulic actuator, and in particular, installs a check valve in its output path that allows free flow in the direction of the hydraulic actuator connected to the output path. , A flow direction control valve device for opening the check valve so as to obtain a control flow in response to the movement of the main valve spool from the neutral position to the other.

[0002]

2. Description of the Related Art As such a flow direction control valve device,
The present inventors have envisioned a flow direction control valve device as shown in FIG. 6 before contemplating the present invention.

That is, A and B are hydraulic actuators C.
A check valve D is installed in the output path B, which is an output path connected to. When the main valve spool S is in the neutral position E0 as shown in the drawing, the output passages A and B are cut off from the supply passage P connected to the hydraulic pressure source and the return passage R connected to the tank, so that the left side of the main valve spool S is cut off. At the switching position E2, the output path A is returned to the return path R.
In addition, the output path B leads to the supply path P, and the output path A leads to the supply path P and the output path B leads to the return path R at the switching position E1 on the right side in the drawing.

The check valve D is a free flow when it flows in the direction of the hydraulic actuator C, has a valve body D0 which is biased in the opening direction by a spring D1, and has a throttle passage D2.
Has a back chamber D3 communicating with the outflow side at the time of free flow, and a drain passage F for communicating this back chamber D3 to the tank through the return passage R is provided, and this drain passage F is formed by the main valve spool S. , The neutral position E0 and the left switching position E2 are closed, and the right switching position E1 is opened.

As a result, when the main valve spool S takes the left switching position E2, the check valve D moves open when its valve body D0 receives the liquid pressure of the liquid supplied from the supply path P on the pressure receiving surface D4. However, when the hydraulic actuator C becomes a free flow, the hydraulic actuator C moves upward, and when the main valve spool S takes the right switching position E1, the drain passage F communicates with the return passage R.
The hydraulic pressure in the back chamber D3 that presses the valve body D0 in the closing direction decreases due to the restriction of the inflow by the throttle passage D2, and the valve body is caused by the hydraulic pressure of the return liquid from the hydraulic actuator C that acts on the pressure receiving surface D5. D0 opens and the hydraulic actuator C operates downward, and at the neutral position E0 of the main valve spool S, the drain passage F closes, so that the inside of the back chamber D3 becomes the hydraulic pressure of the return liquid of the hydraulic actuator C. They become equal, the valve body D0 is closed, and the hydraulic actuator C is stopped and held.

[0006]

A check valve D having such a structure
Cannot be avoided only by the main valve spool S when the output passage B is pressurized when the hydraulic actuator C is stopped and held, as in the case where the hydraulic actuator C is loaded downward as shown in the figure. This is provided in order to minimize leakage and to favorably hold the hydraulic actuator C in a stopped state.

However, in such a structure, since the drain passage F is closed by the main valve spool S, leakage occurs through the drain passage F through the sliding gap of the main valve spool S, and the hydraulic pressure is increased. There is a problem that the stopping and holding of the actuator C cannot be properly obtained.

The present invention solves these problems.
When the main valve spool is set to the neutral position, the flow direction control valve device is designed so that leakage through the drain passage leading to the back chamber of the check valve can be further reduced and good stop holding of the hydraulic actuator can be obtained. It will be realized.

[0009]

Therefore, according to the present invention, the main valve spool, which is biased to the neutral position by the spring, is urged in one axial direction by the internal hydraulic pressure and in the other axial direction. In addition to providing a pilot chamber, a pilot pressure control device that controls the pressure in the pilot chamber to move the main valve spool in the axial direction is provided, and at the neutral position of the main valve spool, the supply path connected to the hydraulic pressure source and the connection return to the tank are returned. The output path connected to the hydraulic actuator, which is disconnected from each path, moves to the supply path by moving from the neutral position of the main valve spool to one side in the axial direction, and moves from the neutral position of the main valve spool to the other side in the axial direction. It is a flow direction control valve device that communicates with each of the return paths by means of a check valve that allows free flow in the direction of the hydraulic actuator in the output path. A valve body with a pressure receiving surface that receives the hydraulic pressure on the inflow side and the outflow side in the open direction in the free flow direction, a spring that urges the valve body in the closing direction, and a throttle passage on the outflow side in the free flow direction. A drain passage communicating with the back chamber for pressing the valve body in the closing direction by the internal hydraulic pressure is provided, and a drain passage for communicating the back chamber of the check valve with the tank is provided, and the drain passage is spring-biased. A normally closed type on-off valve that is operated from the closed state to the open state by pilot operation according to the pressure change in the pilot chamber when the main valve spool moves from the neutral position to the other axial direction is installed. .

[0010]

According to the structure of the present invention, the drain passage is opened / closed by an opening / closing valve other than the main valve spool.
This on-off valve opens and closes the drain passage with a small flow rate, so compared to the main valve spool, the valve body may have a smaller shape and a smaller diameter, and the valve body may have a sliding clearance that induces leakage. Even if it is necessary, the flow area of leakage due to such a sliding gap can be made small, the leakage through the drain passage can be made extremely small, and the hydraulic actuator connected to the output passage can be stopped and held well.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3, reference numeral 1 denotes a valve main body provided with a valve hole 3 for accommodating a main valve spool 2 movably in an axial direction,
A connection block 4 is connected to the valve body 1 as shown in the circuit diagram of FIG. The valve hole 3 has a supply port P at the center,
Output ports A and B are provided on both outer sides thereof, and return ports R1 and R2 are further provided on both outer sides thereof, and a supply passage 6 connected to the hydraulic pressure source 5 is provided from the connection block 4 to the valve body 1. A return passage 9 communicating with the supply port P via the check valve 7 and connected to the tank 8 has respective return ports R1 and R2.
It is provided to communicate with.

Numerals 10 and 11 denote output paths communicating with the output ports A and B, respectively, and connection portions 10A and 1 with a screw, respectively.
As shown in FIG. 3, the cylinder C having a piston loaded in the backward direction as a hydraulic actuator is connected to the output chamber 11 through the head chamber 1A and the rod chamber 10 through the rod chamber 1A.

A check valve 12 is installed in the output path 11,
The check valve 12 has a valve body 12B that is seated on the valve seat 12A to close the output passage 11, and a spring 12C that presses the valve body 12B in the seating direction. It has pressure receiving surfaces 12F and 12G (see FIG. 3) that receive the hydraulic pressures on the output port B side and the connecting portion 11A side of the valve seat 12A, respectively, in the opening direction. The spring 12C is installed in the back chamber 12D at the back of the valve body 12B, and the back chamber 12D is connected to the valve body 12B.
The connecting portion 11 of the valve seat 12A by the throttle passage 12E provided in the
It communicates with the A side and presses the valve bodies 12, 13 in the seating direction by the hydraulic pressure inside the A side, and the connecting portion 1 of the output path 11 is connected.
The valve body 12B is separated from the valve body 12B during the flow in the 1A direction, and a free flow is obtained.

Reference numerals 13 and 14 denote pilot chambers formed at both ends of the main valve spool 2. Each pilot chamber 13, 14 presses the main valve spool 2 to a neutral position as shown in FIG. A spring 16 is installed. A pilot supply passage 17 is connected to the pilot chambers 13 and 14 via throttles 18 and 19, respectively, and electromagnetically operated relief valves 20 and 21 are connected to the pilot supply passages 17.

The relief valves 20 and 21 have the same structure, and the relief valve 20 will be described with reference to FIG. 1. An inlet hole 23 for communicating the pilot chamber 13 with an outlet chamber 22 communicating with the return passage 9 through a passage not shown. Is provided to form a valve seat 24 at the end of the outlet chamber 22 side, and a movable iron core 26 of the solenoid 25 is formed.
A valve body 27 is provided on the valve body 27 and is pressed by a pressure adjusting spring 28 together with the movable iron core 26 in the seating direction. Reference numeral 29 denotes a fixed iron core, and when the coil 30 of the solenoid 25 is energized, the movable iron core 26 receives a suction force in the direction opposite to the spring force of the pressure adjusting spring 28, whereby the set pressure when the coil 30 is de-energized. Is maximized, and the set pressure is reduced in accordance with an increase in the current supplied to the coil 30.

The throttle 18 and the relief valve 20 and the throttle 19 and the relief valve 21 are respectively used to control the pilot chamber 1
Pilot pressure control devices 31 and 32 that control the pressures 3 and 14 to the set pressures of the relief valves 20 and 21 are configured. The pilot supply passage 17, as shown in FIG.
In the connection block 4, the pressure reducing valve 33 is installed and branched from the supply path 6, where the set pressure of the pressure reducing valve 33 is
It is selected to be equal to the maximum set pressure that can be obtained when the relief valves 20 and 21 are not energized.

Reference numeral 34 is an open / close valve which is interposed in a drain passage 35 (shown in a circuit diagram in FIG. 3) for communicating the back chamber 12D of the check valve 12 with the return passage 9 and opens / closes the drain passage 35. As shown in FIG. 2, the on-off valve 34 is a spool-shaped valve body 34C that opens and closes an inlet chamber 34A that communicates with the back chamber 12D of the check valve 12 and an outlet chamber 34B that communicates with the return passage 9.
And the valve body 34C by means of a spring 34D.
A normally closed valve is formed by pressing A and 34B in the closing direction. Further, the valve body 34C is guided by a through hole 34E communicating with the inlet hole 23 of the relief valve 20 by the hydraulic pressure of the pilot chamber 13 to both chambers 34A. , 34B are pressed in the closing direction, and the hydraulic pressure of the pilot supply passage 17 guided by the through hole 34F is pressed in the opening direction of both chambers 34A, 34B.

The main valve spool 2 has a central land 2A,
It has lands 2B, 2C on both sides thereof, and in the illustrated neutral position, these lands 2A, 2B, 2C block the output ports A, B from the supply port P and the return ports R1, R2, and from the neutral position. By moving to the left (at the switching position E1 in FIG. 3), the land 2A supplies the supply port P.
And output port B, and output port A by land 2B
And the return port R1 are communicated, and by moving from the neutral position to the right (at the switching position E2 in FIG. 3), the land 2A communicates the supply port P and the output port A, and the land 2C communicates the output port B and the return port R2. According to the position of the main valve spool 2, the land 2A and the land 2C are provided between the supply port P and the output port B, and between the output port B and the return port R.
Flow rate control taper portions 2D and 2E are provided between the two to provide a flow opening having a flow area that gradually changes.

Reference numeral 2F is a vent switching groove provided in the main valve spool 2, and an inflow groove 37 provided in the connection block 4 through which a vent passage 36A (see FIG. 3) of the relief valve 36 for controlling the supply pressure communicates. The outflow groove 38 communicating with the return path 9 is passed between the grooves 37 and 38 when the main valve spool 2 is at the neutral position shown in the drawing and when the main valve spool 2 is moved to the right from the neutral position. When moving to the left from the position, the gap between the grooves 37 and 38 is cut off. Here, in the state where the vent passage 36A communicates with the return passage 9 through the vent switching groove 2F, the relief valve 36 is connected to the supply passage 6 by the pressure reducing valve 3.
When the vent valve 36A is opened to such an extent that a pressure as low as the set pressure of 3 is generated and the communication of the vent passage 36A to the return passage 9 is cut off, the relief valve 36 exhibits the original high set pressure. .

Next, the operation of this embodiment will be described. In the illustrated state, the solenoids 25 of the relief valves 20 and 21 are closed because the solenoid 25 is not energized, the hydraulic pressures in the pilot chambers 13 and 14 are the same, and the main valve spool 2 is provided with the spring 16
Is held in the neutral position by. The pilot supply passage 17 and the pilot chamber 13 have the same pressure, and the opening / closing valve 34 closes the drain passage 35 by the spring 34D. Therefore, in the check valve 12, in the back chamber 12D,
The hydraulic pressure from the head chamber of the hydraulic cylinder C acts and the valve body 1
2B is pressed against the valve seat 12A together with the spring 12C to be seated. The relief valve 36 causes the vent passage 36 </ b> A to communicate with the return passage 9 so that only a low pressure is generated in the supply passage 6, and the supply liquid from the hydraulic pressure source 5 is returned from the return passage 9 to the tank 8. There is.

At this time, the pressurized liquid in the head chamber of the hydraulic cylinder C is favorably prevented from leaking to the output port B side by closing the check valve 12, and the back chamber of the check valve 12 is closed. Although some leakage is inevitably generated from the inflow chamber 34A of the on-off valve 34 communicating with 12D to the outflow chamber 34B through the sliding gap of the valve body 34C of the on-off valve 34, this valve body 34
Since C can be made small in diameter only by opening / closing the drain passage 35 through which a small flow rate flows, the flow area due to the sliding gap can be made sufficiently small, leakage can be suppressed sufficiently small, and the hydraulic cylinder C can be stopped well. Can hold

Here, the solenoid 25 of the relief valve 21
When the valve is energized, the relief valve 2 is opened, and the hydraulic pressure in the pilot chamber 14 is controlled to the set pressure lowered according to this current. On the other hand, since the inside of the pilot chamber 13 has a hydraulic pressure corresponding to the maximum set pressure of the relief valve 20, the pressure to the left acting on the main valve spool 2 is pushed based on the pressure difference between these chambers 13 and 14. The main valve spool 2 is moved to a position where the pressure and the spring force of the spring 16 installed in the pilot chamber 14 are balanced.
Moves to the left from the neutral position and the output port A and the return port R1 communicate with each other, and the output port A and the output port A through the flow opening having the flow area corresponding to the movement amount of the main valve spool 2 by the taper portion 2D. The port B is communicated.

In response to the leftward movement from the neutral position of the main valve spool 2, the inflow groove 37 and the outflow groove 38 are closed, and the relief valve 36 is disconnected from the vent passage 36A and the return passage 9. The supply passage 6 is pressure-controlled to its original high set pressure, and the supply liquid from this supply passage 6 is subjected to meter-in flow rate control in accordance with the current at the flow opening formed by the taper portion 2D. , The valve body 12 of the check valve 12
B is pressed against the pressure receiving surface 12F thereof to be separated from the pressure receiving surface 12F, and is supplied to the head chamber of the hydraulic cylinder C to raise the cylinder C. At this time, the pilot chamber 13 and the pilot supply passage 17 have the same pressure, and the opening / closing valve 34 is
It's closed.

From the illustrated state, when the relief valve 21 is left as it is and the solenoid 25 of the relief valve 20 is energized, the hydraulic pressure in the pilot chamber 13 is set by the relief valve 20 in accordance with the energized current. The pressure is controlled by the pressure so that both pilot chambers 13,
Rightward pressing force based on the pressure difference of 14 and the pilot chamber 1
The main valve spool 2 moves to the right from the neutral position to the equilibrium position with the spring force of the spring 16 installed in 3.

As a result, the supply port P and the output port A
And the output port B and the return port R2 are communicated with each other through a circulation opening having a circulation area corresponding to the amount of movement of the main valve spool 2 by the taper portion 2E. And
Since there is a pressure difference between the hydraulic pressures in the pilot chamber 13 and the pilot supply passage 17, the opening / closing valve 34 opens its valve body 34C against the spring 34D, and the check valve 12 of the check valve 12 is opened via the drain passage 35. The back chamber 12D communicates with the return path 6.
Therefore, the valve body 12B of the check valve 12 which receives the action of the pressurized liquid from the head chamber of the hydraulic cylinder C on the pressure receiving surface 12G.
Is separated from the inside of the back chamber 12D against the spring 12C by restricting the flow rate of the inflow in the throttle passage 12E and decreasing the pressure, and the flow opening of the taper portion 2E causes the meter corresponding to the current to flow. The hydraulic cylinder C is moved downward by receiving the out flow rate control.

At this time, the vent passage 36A of the relief valve 36 is connected to the return passage 6 via the vent switching groove 2F of the main valve spool 2 and is supplied to the hydraulic cylinder 12 in the supply passage 6. The liquid continues to have a low pressure, but the hydraulic cylinder C is loaded in the piston retreating direction, so that the descending operation is performed without any hindrance.

As described above, according to this embodiment, the check valve 12 is used when the output port B is connected to the return port R2.
Check valve 12 by opening the main valve spool 2 and another on-off valve 34 interposed in the drain passage 35 from the back chamber 12D of
Since the valve body 34C of the on-off valve 34 can be made smaller in diameter, the opening area of the sliding gap of the valve body 34C between the inflow chamber 34A and the outflow chamber 34B can be made smaller, and the chambers 34A and 34B can be controlled. Since the spaces can be largely separated regardless of the movement amount of the main valve spool 2, the valve body 34
Leakage through the sliding gap of C can be made sufficiently small, and the hydraulic cylinder C can be stopped and held well. Further, as compared with the case where the drain passage is opened and closed by the main valve spool as in the conventional example, the main valve spool can be shortened and a small-sized valve device can be obtained.

In this embodiment, the valve body 3 of the opening / closing valve 34 is
Although the hydraulic pressure of the pilot supply passage 17 is applied to 4C in the opening direction, the hydraulic pressure applied in the opening direction may be introduced from the pilot chamber 14.

FIG. 4 shows another embodiment in which the connection block 4 as shown in FIG. 3 is omitted. To describe the difference from the previous embodiment, the electromagnetically operated relief valves 20 and 21 in each pilot pressure control device 31 and 32.
Means that when the coil in the solenoid is de-energized, the set pressure becomes zero and the set pressure increases in accordance with the increase in the energized current. The check valve 12 is installed in the drain passage 35 from the back chamber 12D. The opening / closing valve 34 acts on its valve body in the closing direction with the hydraulic pressure introduced from the right pilot chamber 13 and in the opening direction with the hydraulic pressure introduced from the left pilot chamber 14.

The neutral position of the main valve spool 2 is obtained by deenergizing the solenoids of both relief valves 20 and 21, and the main valve spool 2 is moved leftward from the neutral position to switch position E1. To obtain a switching position E2 by moving the main valve spool 2 from the neutral position to the right to obtain a switching valve E2, an appropriate current is applied to the solenoid of the relief valve 20. And increase the hydraulic pressure in the pilot chambers 13 and 14, respectively,
When the main valve spool 2 moves from the neutral position to the right,
When the pilot chamber 13 has a lower pressure than the pilot chamber 14, the on-off valve 34 is opened, the check valve 12 is opened, and its control flow is obtained. Is obtained.

In this case, as shown in FIG. 5, the on-off valve 34 in the drain passage 35 does not act on the valve body from the hydraulic pressure from the pilot chamber 13, but the hydraulic pressure from the pilot chamber 14 to the spring. Alternatively, only the action in the opening direction may be performed.

Further, although the four-port type having two output paths is shown, it may be configured as a three-port type having only one output path, and the pilot pressure control device is constituted by a combination of a throttle and a relief valve. Although configured, a pressure reducing valve can be used instead of this.

[0024]

As described above, according to the present invention, since the on-off valve different from the main valve spool is provided in the drain passage from the back chamber of the check valve, the on-off valve is a drain with a small flow rate. Since the valve body can be small in shape and diameter because the passage is opened and closed, and even if a sliding gap that induces leakage in the valve body is required, the flow area due to leakage can be reduced, so leakage through the drain passage is prevented. The number can be reduced, and the hydraulic actuator can be stopped and held satisfactorily. Further, the main valve spool can be shortened and a small-sized valve device can be obtained, as compared with the case where the drain passage from the back chamber of the check valve is opened and closed by the main valve spool as in the conventional example.

[Brief description of drawings]

FIG. 1 is a sectional view of a flow direction control valve device showing an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a main part in one embodiment of the present invention.

FIG. 3 is a hydraulic circuit diagram showing an embodiment of the present invention.

FIG. 4 is a hydraulic circuit diagram showing another embodiment of the present invention.

FIG. 5 is an explanatory view showing still another embodiment of the present invention.

FIG. 6 is a hydraulic circuit diagram showing a conventional example.

[Explanation of symbols]

 2 main valve spool 6 supply path 9 return path 11 output path 12 check valve 12B valve body 12C spring 12D back chamber 12E throttle passage 12F, 12G pressure receiving surface 13, 14 pilot chamber 16 spring 17 pilot supply passage 31, 32 pilot pressure control Device 34 On-off valve 34C Valve body 34D spring 35 Drain passage

Claims (4)

[Claims] 1. A pilot chamber for pushing a main valve spool biased to a neutral position by a spring to one axial direction by an internal hydraulic pressure and a pilot chamber for pushing the main valve spool to the other axial direction are provided. A pilot pressure control device that controls the pressure in the pilot chamber to move in the axial direction is provided, and at the neutral position of the main valve spool, the supply passage connected to the hydraulic pressure source and the return passage connected to the tank are disconnected from the hydraulic actuator. Flow direction control that connects the output path of the connection to the supply path by moving from the neutral position of the main valve spool in one axial direction and to the return path by moving from the neutral position of the main valve spool to the other axial direction In the valve device, a check valve that allows free flow in the direction of the hydraulic actuator is provided in the output path. A valve body having a pressure receiving surface that receives pressure in the opening direction, a spring that urges the valve body in the closing direction, and a flow passage that communicates with the outflow side during free flow through a throttle passage to close the valve body with internal hydraulic pressure. With a back chamber that presses in the same direction, and a drain passage that connects the back chamber of the check valve to the tank is provided.The drain passage is a spring-biased normally closed type and the main valve spool is in the neutral position. A flow direction control valve device comprising an on-off valve which is operated by a pilot operation from a closed state to an open state according to a pressure change in a pilot chamber when moving from one direction to another direction in the axial direction. 2. An on-off valve installed in a drain passage has a valve body urged to a closed position by its spring, and a liquid introduced from a pilot chamber that axially presses the main valve spool by an internal hydraulic pressure. The pressure is applied in the closing direction, and the hydraulic pressure introduced from a pilot chamber that presses the main valve spool in the other axial direction by the internal hydraulic pressure is applied in the opening direction.
The flow direction control valve device according to. 3. An on-off valve installed in a drain passage is provided with a valve body urged to a closed position by its spring, and a liquid introduced therein from a pilot chamber for axially pressing the main valve spool in one axial direction. Pressure in the closing direction and hydraulic pressure introduced from the supply passage to the pilot pressure control device in the opening direction.
The pilot chamber that presses the main valve spool in one axial direction by the internal hydraulic pressure is operated by the pilot pressure control device when the internal hydraulic pressure moves the main valve spool from the neutral position to the other axial direction. 2. The flow direction control valve device according to claim 1, wherein the spool is reduced more than in the neutral position. 4. An on-off valve installed in the drain passage is provided with a valve body for preventing a hydraulic pressure from a pilot chamber, which presses the main valve spool in the other axial direction by the internal hydraulic pressure, against the biasing force of a spring. The pilot chamber that presses the main valve spool to the other axial direction by the internal hydraulic pressure is used when the internal hydraulic pressure moves the main valve spool from the neutral position to the other axial direction. 2. The flow direction control valve device according to claim 1, wherein the pilot pressure control device increases the main valve spool more than when the main valve spool is in the neutral position.