JPH0633203Y2 - Pilot control valve operating circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is an improvement of an operation circuit of a pilot control valve, in particular, an operation circuit of a pilot control valve capable of relieving an impact when a hydraulic actuator stops operating. It is about.

(Prior Art) In the conventional operation circuit of a general pilot control valve 1 ', as shown in FIG. 3, left and right pilot ports 2a', 2b 'are respectively provided with flow control valves 3a such as check valves with throttle valves. The pilot pressure in the return pilot line 5'or 4'is adjusted by connecting the pilot lines 4'and 5'through the lines 3'and 3b 'so that the pilot pressure from the pilot valve 6'is supplied and discharged. When stopping the hydraulic actuator by suppressing a sudden drop with the throttle valve,
The impact of the hydraulic actuator is reduced.

(Problems to be solved by the invention) In the operation circuit of the conventional pilot control valve shown in FIG. 3, when the pilot valve 6'is switched, the flow rate in the return pilot line 5'or 4 ' The pressure in the upstream pipes 5a 'or 4a' of the control valves 3a ', 3b' rapidly drops, but the pressure in the downstream pipes 5b 'or 4b' of the flow control valves 3a ', 3b' is equal to the flow rate. Due to the action of the control valves (check valves) 3a 'and 3b', the pressure drops only gradually.

For this reason, as described above, the stop of the hydraulic actuator can be moderated and the impact applied to the hydraulic actuator at the time of stop can be mitigated, but the pressure remains in the return-side pilot conduit 5b 'or 4b'. When the reverse operation is performed, the switching operation of the pilot control valve 1'is delayed due to the residual pressure.

Therefore, when the hydraulic actuator is suddenly moved in the reverse direction, the sense of switching operation of the pilot control valve 1 ′ and the actual operation of the hydraulic actuator may deviate from each other, and an operation such as an operation for avoiding danger may be performed. There was a malfunction that could not be handled.

(Means for Solving the Problem) The present invention is to connect a pilot control line from a pilot valve by connecting a pilot line having a flow control valve such as a check valve with a throttle valve to each of the left and right pilot ports of the pilot control valve. In the operation circuit of the pilot control valve for supplying / discharging, the pipes branched from the previous stage of the flow control valve of the pipe are connected to the pilot ports of the left and right, respectively between the left and right pilot pipes. When a pilot pressure is supplied to the pilot pipe of, the reverse operation switching valve that switches to connect the pipe branched from the latter stage of the flow control valve of the other pilot pipe to the tank is installed. During operation, stop the hydraulic actuator gently to reduce the impact on the hydraulic actuator and to avoid danger. Operation, etc.
When the hydraulic actuator is to be reversely operated in an emergency, a deviation between the feeling of the pilot control valve switching operation and the actual operation of the hydraulic actuator, that is, a delay in the switching operation of the pilot control valve is prevented.

(Embodiment) The present invention will be described below with reference to an embodiment shown in FIGS. 1 and 2.

Reference numeral 1 is a pilot control valve, and the pilot ports 2a and 2b on the left and right of the valve 1 are pilot valves via pilot lines 4 and 5 in the middle of which flow control valves such as check valves with throttle valves 3a and 3b are provided. Connected to 6.

A reverse operation switching valve 7 is provided between the pilot pipe lines 4 and 5.

Left and right pilot ports 8a, 8 of the reverse operation switching valve 7
b is connected to the pipelines 9a and 9b branched from the preceding pipelines 4a and 5a of the flow control valves of the pilot pipelines 4 and 5, respectively.

Further, the two hydraulic oil ports of the reverse operation switching valve 7 are connected to the downstream side pipelines 4b and 5b of the flow control valves of the pilot pipelines 4 and 5.
Are connected to the branched pipelines 10a and 10b, respectively, and when the pilot pressure acts on one pilot pipeline 4a or 5a to switch the reverse operation switching valve 7, the other pilot pipeline 5b or 4b is switched. It is adapted to be connected to the tank 11 via a branch line 10b or 10a.

(Operation) When the pilot valve 6 is operated to the right or left from the state shown in FIG. 1, the pilot port 2a or 2b of the pilot control valve 1 and the pilot of the reverse operation switching valve 7 are piloted via the pilot conduit 4 or 5. Port 8a or 8
The pilot pressure is supplied to each of b, and the pilot control valve 1 and the reverse operation switching valve 7 are switched in the operating direction.

By this switching operation, the downstream side pipeline 5b or 4b of the flow control valve of the pilot pipeline 5 or 4 on the non-operating side (return side) is connected to the tank 11 via the reverse operation switching valve 7, so that the non-operating side ( Even if there is a residual pressure in the downstream side pipeline 5b or 4b of the flow control valve of the return side) pilot pipeline 5 or 4, this residual pressure is dropped to the tank 11, and the pilot control valve 1 is smoothly switched.

When the pilot valve 6 is returned to the neutral position by a normal operation from this state, the pressure in the upstream-side pipeline 4a or 5a of the flow control valve 3a or 3b of the pilot pipeline 4 or 5 rapidly drops, and the reverse operation switching is performed. The valve 7 returns to the neutral position.

Therefore, the residual pressure in the downstream side pipeline 4b or 5b of the flow control valve of the pilot pipeline 4 or 5 is determined by the flow control valve (throttle valve) 3a.
Alternatively, the hydraulic actuator is gently released via 3b, and the hydraulic actuator is gently stopped.

On the other hand, if the pilot valve 6 is operated in reverse at once without maintaining the neutral position, the pressure in the upstream side pipeline 4a or 5a of the flow rate control valve 3a or 3b of the pilot pipeline 4 or 5 will drop rapidly, and Of the flow control valve 3b or 3a of the pilot line 5 or 4 in the direction 5a or 4a on the upstream side of the flow control valve 3b or 3a
Since the pilot pressure is supplied inside, the reverse operation switching valve 7 also switches in the opposite direction.

Therefore, the residual pressure in the upstream side pipeline 4b or 5b of the flow control valve of the pilot pipeline 4 or 5 is rapidly released to the tank 11 via the reverse operation switching valve 7, so that the pilot control valve 1 is switched by the residual pressure. It switches quickly without disturbing the operation.

Therefore, the hydraulic actuator operates in reverse with almost no operation delay.

(Effects of the Invention) According to the present invention, with a simple configuration in which a reverse operation switching valve is added to the conventional operation circuit, the stop of the hydraulic actuator is moderated during normal operation as in the conventional case, and the impact on the hydraulic actuator is reduced. Can be relaxed,
When the hydraulic actuator is to be operated in the reverse direction in an emergency, such as an operation to avoid a danger, the pilot control valve can be switched smoothly as in the case where a flow control valve such as a check valve with a throttle valve is not installed. There is no discrepancy between the operation feeling and the actual operation of the hydraulic actuator, and the hydraulic actuator can be operated easily and safely.

Further, since the pressure oil in the pilot line is returned to the tank via the reverse operation switching valve, the replacement of the pressure oil in the pilot line with the oil in the hotter tank is promoted, and the response delay at low temperature is also delayed. It has the effect that it can be resolved.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a schematic diagram of the reverse operation switching valve, and FIG. 3 is a conventional circuit diagram. 1: Pilot control valve 2a, 2b: Pilot port 3a, 3b: Flow rate control valve (check valve with throttle valve) 4, 5: Pilot line 6: Pilot valve 7: Reverse operation switching valve 8a, 8b: Pilot port 11: tank

Claims (1)

[Scope of utility model registration request] 1. Pilot lines (4, 5) in which flow control valves (3a, 3b) such as check valves with throttle valves are provided in the left and right pilot ports (2a, 2b) of the pilot control valve (1), respectively. In the operation circuit of the pilot control valve for connecting and disconnecting the pilot pressure from the pilot valve (6), between the left and right pilot pipes (4, 5) 3a, 3b) and the pipes (9a, 9b) branched from the former stages, respectively.
b) is connected to the left and right pilot ports (8a, 8b), and when the pilot pressure is supplied to one pilot line (4 or 5), the flow control valve (1) of the other pilot line (5 or 4) An operation circuit for a pilot control valve, characterized in that a reverse operation switching valve (7) for switching the pipeline (10b, 10a) branched from the latter stage of (3a, 3b) is connected to the tank (11). .