JPH0942207A - Operation circuit of pilot control valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To relieve shocks at times of a stop, a reverse operation, and a start using only general purpose parts by connecting pressure oil to an oil tank with an opening and closing valve linking with the spool of a pilot control valve only when the spool is in a neutral state. SOLUTION: When the lever 11 of an operation valve 6 is turned to the left side at a start time, pressure oil is supplied to a port 2b via the check valve of a flow control valve 3b While the pressure oil is supplied to the pilot port 8b of a directional control valve 7 from a pipeline 5a, and a pipeline 10a and a pipeline 24a are connected. Accordingly, the pressure oil of a pipeline 4b flows to an opening and closing valve 23 via pipelined 10a, 24. The spool of the pilot control valve 1 starts to move rapidly in the early stage of the start time, but the input/output port of the opening and closing valve 22 is shut off with movement so that the pressure oil of the pipeline 4b returns to an oil tank 11 via the throttle valve of a flow control valve 3a passing the operation valve 6. Thereby, the moving speed of the control valve 1 is reduced, and the oil volume flowing into an actuator is reduced so as not to give any shock to an operator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operating circuit for a pilot control valve by hydraulic pressure, and more particularly to a technical field relating to an operating circuit having improved operating characteristics.

[0002]

2. Description of the Related Art A pilot operation circuit utilizing hydraulic pressure is used for remote operation and automatic operation of construction machines, machine tools, vehicles and robots which require a large force.
In recent years, inventions and inventions have been made to improve the operation characteristics, particularly the dynamic characteristics, of such a hydraulic pilot operation circuit. For example,
Japanese Utility Model Publication No. 6-33203 discloses a circuit with improved characteristics in emergency reverse operation. This circuit will be described with reference to FIG. As shown in FIG. 6, the pilot port of the pilot valve 6 (corresponding to the operation valve of the present application) is connected to the pilot port 2a of the pilot control valve 1 (corresponding to the pilot control valve of the present application) via the flow rate control valves 3a and 3b. And 2b are connected to each other by pipe lines 4 and 5, respectively. Further, the pilot ports 8a and 8b of the reverse operation switching valve 7 are connected to the pipelines 4 and 5 by branch pipelines 9a and 9b branched from the preceding pipelines 4a and 5a of the pipelines 4 and 5, respectively. Further, the input port of the reverse operation switching valve 7 is
The pipelines 4 and 5 are connected to the pipelines 4 and 5 by branch pipelines 10a and 10b branched from the latter-stage pipelines 4b and 5b. The output port of the reverse operation switching valve 7 is connected to the oil tank 11.

Therefore, in the above circuit, when the actuator 30 is activated, the pilot pressure oil from the pilot valve 6 is transferred to the pipe 5a → the control valve 3b → the pipe 5b (or the pipe 4).
It is supplied to the pilot port 2b (or 2a) of the pilot control valve 1 via a → control valve 3a → pipe line 4b). At this time, the pressure oil remaining in the pipeline 4b is returned to the oil tank 11 via the pipeline 10a and the reverse operation switching valve 7. Therefore, the spool of the pilot control valve 1 rapidly moves, and the pressure oil rapidly flows into the actuator 30.
Further, during emergency operation of the actuator, pressure oil is supplied from the pilot valve 6 to the pilot port 2a (or 2b) of the pilot control valve 1 in the reverse direction.
On the other hand, the pressure oil remaining in the pipeline 5b is the pipeline 10b (or 10
a), it is returned to the oil tank 11 via the reverse operation switching valve 7. Therefore, the spool of the pilot control valve 1 suddenly moves in the opposite direction, and the pressure oil rapidly flows into the opposite port of the actuator 30. Next, when the hydraulic actuator is stopped, the pilot pressure oil from the pilot valve 6 is supplied to the conduit 4
It is not supplied to any of a, 9a and 5a, 9b, and the branch pipelines 10a, 10b are blocked. The pilot pressure oil from the pilot ports 2a and 2b of the pilot control valve 1 is gradually supplied to the pilot valve 6 via the flow rate control valves 3a and 3b and returned to the oil tank.

Furthermore, the utility model publication gazette H6-1801
Japanese Patent No. 346098 discloses an operating circuit with improved operating characteristics at startup. This circuit will be described with reference to FIG. However, the same parts are designated by the same reference numerals and the description thereof will be omitted. Figure 6
As can be seen from the comparison with this circuit, this circuit has a switching valve 12a with throttle, instead of the flow control valves 3a and 3b of the circuit described above.
12b is used. FIG. 8 shows a switching valve 12 with a throttle.
It is sectional drawing which showed the structure of b (same as 12a). In the figure, the pressure on the side of the pipeline 5a is from the passage 14 to the hydraulic chamber 1
5, and is transmitted to the pipe line 5b side through the passage 16. Since the biasing force of the spring at start-up is weak, this is ignored, and the pressure Pc on the pipeline 5b side (pilot control valve side) is a condition P
When c × Ac ≧ Pp × Ap is satisfied, the spool 13 moves to the pipeline 5a side (pilot valve side), and the above passage is blocked. Note that Pp is the pressure on the 5a side, Ac, Ap
Is the pressure receiving area on the 5b, 5a side.

According to the above configuration, the passage 14, the hydraulic chamber 15, and the passage 16 are provided until the above relation is satisfied at the time of startup.
When the above relationship is satisfied, the passage 14 is blocked, and the pressure oil on the side of the pipe 5a is supplied to the side of the pipe 5b only from the throttle 17. Therefore, the impact caused by the sudden increase in the hydraulic pressure in the conduit 5b is mitigated. When the emergency reverse operation is performed, the pilot pressure oil is supplied to the conduit 4a side (pilot valve side) of the other throttle-equipped switching valve 12a, and the pilot oil pressure is supplied to the pilot port 2a of the pilot control valve 1. The pressure oil supplied to the pilot port 2b of the pilot control valve 1 is the branch pipe 1
It is returned to the tank 11 via 0b. Therefore, the hydraulic pressure of the pilot port 2a of the pilot control valve 1 increases and the hydraulic pressure of 2b decreases at the same time, so that the pilot control valve 1 starts to operate without delaying the reverse operation of the driver. However, when the oil pressure in the conduit 4b rises, the oil passages 14 → 15 → 16 in the switching valve 12a with a throttle
Is closed and the pressure oil is supplied only from the throttle 17, so that the movement of the pilot control 1 is slowed down. Further, when the pilot control valve 1 is stopped, the pressure oil flow from the pilot ports 2a and 2b is the switching valve 12 with the throttle valve.
Since it is limited by a and 12b and is supplied to the pilot valve 6, the impact at the time of stop is mitigated.

[0006]

In the former circuit, the hydraulic pressure is supplied to the pilot control valve 1 when the actuator is started, but the hydraulic pressure from the pilot valve 6 is supplied to the pilot control valve as it is. There is a problem in the sense of operation because it gives a shock to the driver when the vehicle starts. The latter circuit does not have such a problem, but uses a switching valve with a throttle. Therefore, it is necessary to specially manufacture such a valve,
There is a problem that the manufacturing cost is high. The present invention
It is made against the background as described above, and an object thereof is to provide a pilot hydraulic circuit which uses only general-purpose components and has a shock mitigated at the time of stop, reverse operation and start.

[0007]

In order to solve the above problems, the apparatus according to claim 1 is an operation for selectively supplying and discharging pilot pressure oil and left and right pilot ports of a pilot control valve for controlling an actuator. In the operation circuit of each connected pilot control valve, the pilot ports on the left and right of the valve are connected in the main line with a flow control valve such as a check valve with a throttle valve in the middle of the line. A first branch pipe line and a second branch pipe line branched from the front stage and the rear stage are respectively provided, and the pilot port of the directional control valve is connected between the open ends of the first branch pipe lines, and pilot pressure oil is supplied to one of the main pipe lines. The open end of the second branch line is connected to each input port of the directional control valve so that the other main line is electrically connected to the output port of the directional control valve when supplied, and is linked with the spool of the pilot control valve. An on-off valve is provided, and a return pipe is connected from the output port of the directional control valve to the oil tank via the on-off valve, and the pressure oil from the directional control valve is supplied only when the spool of the pilot control valve is in the neutral state. It is characterized by returning to the tank and shutting off in other cases.

According to the present invention, a conventional operating circuit is provided in conjunction with a spool of a pilot control valve with an aid of a general-purpose on-off valve, and a first branch branched from a front stage and a rear stage of a flow control valve in a main pipeline. A pipe line and a second branch pipe line are respectively provided, and a direction switching valve is provided between the open ends of the first branch pipe lines,
When pilot pressure oil is supplied to one oil supply line, when the pressure oil in the opposite oil supply line starts up, it returns to the oil tank at the initial stage of reverse operation, and then the spool comes to the end of the neutral state. Before that, the return pipe was cut off so that the pilot control valve could not be suddenly fully opened. Therefore, it responds promptly to the start and reverse operations, but no shock occurs. Also, since the return line is blocked when stopped,
No shock occurs.

[0009]

1 is an example of a circuit showing an embodiment of the invention of claim 1. In FIG. Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, the pilot control valve 1 is a directional control valve, such as port A,
Each B is connected to a port of the actuator (see FIG. 6). Pilot port 2 of pilot control valve 1
a and 2b are connected to a pilot valve 6 by main pipe lines 4 and 5 via check valves with throttles 3a and 3b, respectively. The check valves 3a and 3b with throttles are connected in a meter-out circuit system in order to stabilize the movement of the actuator. In addition, the check valve 3 with a throttle in the main pipelines 4 and 5
a, 3b upstream of the pipelines 4a, 5a to the first branch pipeline 9
a and 9b are branched, and the first branch pipelines 9a and 9b
At the open end of the pilot port 8a, 8
b is connected. As the direction switching valve 7, for example, a reverse operation switching valve may be used in which one pilot port (for example, 8b) is supplied with pilot pressure and the other input / output port (right input / output port) is electrically connected. Further, the check lines 3a and 3b with throttles of the main lines 4 and 5 are provided at the subsequent stage of the line 4
The second branch pipelines 10a, 10b are branched from b, 5b, and the other ends of the second branch pipelines 10a, 10b are connected to the same side input port of the switching valve 7.

The spool 21 of the pilot control valve 1 (see FIG.
The spool of the on-off valve 22 is linked to the reference valve (see). The on-off valve 22 may be, for example, a 2-port 3-position switching valve that is in a conducting state at the neutral position and is in a shut-off state at both ends. The input port of the on-off valve 22 is connected to the output port of the directional control valve 7 by the return conduit 24. The output port of the opening / closing valve 22 is connected to the oil tank 11.

FIG. 2 is a diagram showing a conduction / cutoff relationship between the input / output port of the pilot control valve and the input / output port of the opening / closing valve 22. Pilot port 2b of pilot control valve 1
Control valve 1 when pilot pressure oil is supplied to
Ports P and A are conducted, and ports B and T are conducted. In this case, the open / close valve 22 is in the shutoff state. When the pilot pressure oil is supplied to the pilot port 2a of the pilot control valve 1, the ports P and B of the pilot control valve 1 are electrically connected, and the ports A and T are electrically connected. In this case as well, the open / close valve 22 is in the closed state. When the pilot control valve 1 is in the neutral state (each port is in the shutoff state), the open / close valve 22 is in the conductive state. Note that, in FIG. 2, the on-off valve is shut off immediately before the pilot control valve 1 changes from the shut-off state to the conductive state, but the change position is not limited to this, and it may be moved a little earlier. It may be delayed and matched.

This embodiment is configured as described above, and operates as follows at the time of starting, stopping, and emergency reverse operation. That is, consider a case where the pilot pressure oil is supplied to the pipe line 5a when the lever H of the pilot valve 6 is tilted to the left (in the direction of the arrow in the drawing) at the time of startup. In this case, the pilot pressure oil passes through the check valve of the flow rate control valve 3b, flows through the pipe line 5b, and is supplied to the pilot port 2b. On the other hand, the pilot port 8 of the directional control valve 7 is passed through the first branch line 9b branched from the line 5a.
b is supplied with pilot pressure oil, and the pipeline 10a and the pipeline 24 are provided.
Conducts. Therefore, the pressure oil in the pipeline 4b is
It flows to the input port of the on-off valve 22 through the conduit 10a → the conduit 24. Therefore, pilot pressure oil starts to flow into the pilot port 2b of the pilot control valve 1 at the initial stage of startup, and pressure oil in the pipeline on the pilot port 2a side opens and closes in the on-off valve 2
The spool of the pilot control valve 1 starts to move rapidly because the oil is returned to the oil tank 11 through the valve 2.

However, when the spool 21 moves in the starting direction, the oil passage of the input / output port of the opening / closing valve 22 is shut off,
Pipe line 4b → Pipe line 10a → Pipe line 24 → Open / close valve 22 → Pressurized oil flow in the oil tank 11 is cut off, and pressurized oil in the pipe line 4b passes through the throttle valve of the flow control valve 3a and the pilot valve 6. Returned to the oil tank 11. Therefore, the moving speed of the spool 21 of the pilot control valve 1 is reduced. As a result, at the time of start-up, the actuator immediately starts responding to the movement of the lever H of the pilot valve 6, but when it starts moving, its speed is reduced, so the oil flow rate into the actuator is reduced, and the operator is impacted. Never give.

Next, during an emergency operation, the operator instantaneously switches the lever H of the pilot valve 6 in the opposite direction in order to avoid an emergency situation. For example, a case will be described in which the lever H is instantaneously switched in the opposite direction of the arrow in the figure. When the lever H is tilted to the right, pilot pressure oil is supplied to the pipe line 4a, and the pressure oil is supplied to the pilot port 2a of the pilot control valve 1 through the check valve of the flow rate control valve 3a and the pipe line 4b. . At the same time, the pilot pressure oil is also supplied to the port 8a of the directional control valve 7. Therefore, the pressure oil that has been supplied to the pipeline 5b until then is the first branch pipeline 1
0b, the direction switching valve 7, and the opening / closing valve 22 to pass through the oil tank 1
Returned to 1. As a result, the spool 21 of the pilot control valve 1 quickly starts moving in the reverse direction, disconnects the input / output port, and then switches to the reverse connection. When the connection of the input / output port is switched to the reverse connection, the passage of the input / output port of the opening / closing valve 22 is blocked, and the pressure oil in the pipeline 5b passes only the flow control valve 3b and the pilot valve 6 and the oil tank 11 Be returned to. Therefore, the actuator stops immediately when the lever H is switched in the reverse direction,
It begins to move in the opposite direction, but the reverse speed is reduced.

The case of the last stop will be described. A case of returning the lever H from the tilted state to the neutral state will be described. The operation is the same in the opposite case, and the description thereof is omitted. In this case, the supply of pilot pressure oil to the pipelines 4a and 5a is interrupted, and the passages of the input / output ports of the direction switching valve 7 are shut off. Therefore, the pipeline 5
The pressure oil of b is restricted by the flow control valve 3b,
And, it passes through the pilot operated valve 6 and is slowly returned to the oil tank. Therefore, the impact is mitigated even when the vehicle is stopped.

As described above, in this device, the shock is mitigated not only at the time of stop and reverse operation, but also at the time of start-up, and it is composed of only general-purpose parts, and moreover, it is more than the conventional device. Since it can be configured only by adding some parts and changing a part of the piping, there is an effect that the cost can be reduced as compared with the conventional operation circuit.

The embodiments and examples of the present invention have been described in detail above with reference to the drawings. However, the specific configuration is not limited to the embodiments and examples, and is within the scope not departing from the gist of the present invention. Even if the design is changed, it is included in the present invention. For example, the on-off valve may be connected as shown in FIG. 4 and the pilot port may be provided at the end of the on-off valve. Further, the direction switching valve is not limited to the reverse operation switching valve, and a forward operation switching valve may be provided to reverse the connection of the pipelines. Also, a directional valve of another system may be used.
Further, the direction switching valve 7 is not limited to 4 ports,
The three-port switching valve shown in FIG. 5 may be used, and a three-pronged pipe may be used for joining.

[0018]

As described above, according to the configuration of the present invention, since the circuit can be constructed by only general-purpose components, the cost is lower than that of the conventional product. Further, with the configuration as shown in FIG. 3, an already used circuit can be used only by changing the connection of the pipes, so that the present invention can be easily implemented. Further, since a configuration different from the conventional one can be provided, there is an effect that it is useful for abundant technologies.

[Brief description of drawings]

FIG. 1 is a functional configuration diagram showing an embodiment of the present invention.

FIG. 2 is a diagram illustrating a relationship between a pilot control valve and an opening / closing valve of the present embodiment.

FIG. 3 is a view showing a mode of connection of the on-off valves.

FIG. 4 is a diagram showing a mode of connection of the on-off valves.

FIG. 5 is a diagram showing a connection when a 4-port 3-position directional control valve is used.

FIG. 6 is a diagram showing a configuration of a conventional operation circuit.

FIG. 7 is a diagram showing a configuration of another conventional operation circuit.

8 is a diagram showing a detailed cross-sectional view of the switching valve with a throttle shown in FIG.

[Explanation of symbols]

 1 Pilot control valve 2a, 2b Pilot port 4, 5 Main line 6 Operation valve 7 Directional switching valve 8a, 8b Pilot port 9a, 9b 1st branch line 10a, 10b 2nd branch line 11 Oil tank 22 Open / close valve 24 Return Pipeline

Claims (1)

[Claims] 1. The left and right pilot ports of a pilot control valve for controlling an actuator and the left and right pilot ports of an operation valve for selectively supplying and discharging pilot pressure oil are provided in the middle of a pipe such as a check valve with a throttle valve. In the operation circuit of each connected pilot control valve in the main pipeline with the flow control valve interposed, a first branch pipeline and a second branch pipeline branching from the front and rear stages of the flow control valve of the main pipeline are respectively provided. ,
A pilot port of a directional control valve is connected between the open ends of the first branch pipelines, and when pilot pressure oil is supplied to one of the main pipelines, the other main pipeline is electrically connected to the output port of the directional control valve. As described above, the open end of the second branch pipe is connected to each input port of the directional control valve, and an opening / closing valve interlocked with the spool of the pilot control valve is provided, and the opening / closing is performed from the output port of the directional switching valve. A return line is connected to the oil tank via the valve, and when the spool of the pilot control valve is in a neutral state, the pressure oil from the directional control valve is returned to the oil tank, and is shut off otherwise. An operation circuit characterized by the above.