JPH0589902U - Vibration suppression circuit device for hydraulic actuator - Google Patents

Abstract

(57) [Abstract] [Purpose] To suppress the vibrations that occur when stopping hydraulic actuators for construction machinery, etc. to improve operability and reduce operator fatigue. [Structure] Two main pipelines 3, 4 leading to the hydraulic cylinder 1
Are connected by an on-off valve 21. The on-off valve 21 is pilot-operated by the pilot-operated two-way valve 22. The pilot port of the pilot operated two-way valve 22 has a pilot line 9 connecting the pilot operating unit 6 and the directional control valve 5.
The upstream side and the downstream side of the slow return valve 11 provided in the above are respectively connected. When the operating lever 7 is returned to the neutral position, the pilot pressure in the pilot conduit 9 becomes tank-side pressure P _U <direction control valve-side pressure P _{L due} to the action of the throttle 11a.
Due to this pressure difference, the two-way valve 22 is switched for a certain period of time, the on-off valve 21 is opened to communicate the main pipe lines 3 and 4, and vibration when the hydraulic cylinder 1 is stopped is suppressed.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a vibration suppressing circuit device for a hydraulic actuator, and particularly to a hydraulic circuit device suppressing a vibration generated when the operation of a hydraulic cylinder is stopped.

[0002]

[Prior Art]

 A conventional hydraulic actuator drive circuit will be described with reference to FIGS. FIG. 4 shows a boom cylinder drive circuit of a hydraulic excavator, and a pilot operated directional control valve 5 is provided in main pipe lines 3 and 4 connecting a hydraulic cylinder 1 for boom drive and a hydraulic pump 2. The directional control valve 5 is controlled by the pilot operating unit 6 and is switched in synchronism with the movement of the operating lever 7 of the pilot operating unit 6, so that the elevation angle of the boom of the hydraulic excavator can be operated. Reference numeral 8 is a pilot hydraulic pump, 9 and 10 are pilot conduits, and 11 and 12 are slow return valves. The slow return valves 11 and 12 delay the return speed to the neutral position of the directional control valve 5 to reduce the shock generated at the time of switching.

Next, the operation of the boom cylinder drive circuit will be described with reference to the timing chart of FIG. Hydraulic excavator operator t₁When the operation lever 7 is rotated to the right side in FIG.₂At time t, the spool of the directional control valve 5 starts moving from the neutral position C to the L position, and t₃The maximum displacement position is reached at. Operation start of the operating lever 7 t ₁ Delay (t from when the directional control valve 5 is activated)₂-T₁) Is caused by the pressure loss of the pilot system and the elasticity of the pilot hydraulic hose.

When the directional control valve 5 is switched from the neutral position C to the L position, pressure oil from the hydraulic pump 2 is supplied to the piston rod side oil chamber 1 a of the hydraulic cylinder 1 through the directional control valve 5 and the main pipe line 3. Then, the hydraulic cylinder 1 contracts. When the operator returns the operation lever 7 to the neutral position at time t ₄ , the directional control valve 5 is delayed and starts the returning operation at t ₅ , and becomes the neutral position C at t ₆ . The Return speed of the directional control valve ₅ (t ₆ -t 5) is Ru determined by the throttle 11a of the slow return valve 11.

Since the mass of the entire boom of the hydraulic excavator driven by the hydraulic cylinder 1 is large and the inertia is large, when the return operation of the directional control valve 5 is started at t ₅ and the contraction speed of the hydraulic cylinder 1 decreases, the hydraulic cylinder 1 The pressure in the bottom side oil chamber 1b of No. 1 rapidly increases due to the inertia of the boom (P _{1 in} FIG. 5). Then, due to the reaction force, the piston rod 1c of the hydraulic cylinder 1 is extended, and the pressure in the piston rod side oil chamber 1a rises due to this extension operation (P ₂ ). Subsequently, the hydraulic cylinder 1 contracts due to the reaction force of the surge pressure P _{2 in} the piston rod side oil chamber 1a. Then, the contraction and expansion are repeated in sequence, and the pressure in the bottom side oil chamber 1b and the pressure in the piston rod side oil chamber 1a alternately rise to vibrate the piston rod 1c, and gradually the pressure fluctuation is attenuated and the vibration stops. It

[0006]

[Problems to be solved by the device]

 In the conventional hydraulic actuator drive circuit described above, when the operation of a large-mass part such as a boom of a hydraulic excavator is stopped, vibration of the hydraulic actuator occurs due to inertia of the boom or the like, and when the hydraulic actuator stops operating. There is a problem in operability due to easy positioning error.

Further, the vibration of the hydraulic actuator causes the vibration of the main body of the hydraulic equipment, which causes the fatigue of the operator to increase and the work efficiency to decrease. Therefore, there are technical problems to be solved in order to suppress the vibration generated when the hydraulic actuator stops to improve the operability and reduce the physical burden on the operator to improve the work efficiency. This device aims to solve the above problems.

[0008]

This invention is proposed to achieve the above-mentioned object, and in a hydraulic machine in which a hydraulic actuator is controlled by a pilot operated directional control valve, the pilot operated part and the directional control are provided. A flow control valve is provided in a pilot line connecting with the valve, the pilot ports of the pilot operation two-way valve are connected before and after the flow control valve, and the hydraulic actuator and the directional control valve are connected. A hydraulic circuit in which the main pipelines of the book are connected by an on-off valve, and the on-off valve is controlled by the pilot operated two-way valve, wherein the pilot operated two-way valve opens and closes when the pilot pressure of the directional control valve decreases. A vibration suppressing circuit device for a hydraulic actuator configured to open a valve.

[0009]

[Action]

 When the operating lever is returned from the drive position to the stop position, the pilot pressure oil supplied to the directional control valve returns to the tank. At this time, a pressure difference occurs between the outlet and the inlet of the flow control valve provided in the pilot line due to the flow limiting action. This pressure difference causes the pilot-operated two-way valve to switch, opening and closing the on-off valve interposed between the two main pipelines by applying pilot pressure to open the two main pipelines. As a result, the generation of surge pressure caused by inertia when the hydraulic actuator stops is suppressed, and the hydraulic actuator stops smoothly. When the pressure in the pilot line decreases and the pressure difference decreases below a certain level, the pilot operated two-way valve switches to the normal position, the on-off valve closes and the hydraulic actuator stops.

[0010]

【Example】

 An embodiment of the present invention will be described below in detail with reference to FIGS. The circuit configurations of the hydraulic cylinder 1, the directional control valve 5, the hydraulic pumps 2 and 8, the pilot operating unit 6 and the slow return valves 11 and 12 shown in FIGS. 1 to 3 are the same as those shown in FIG. 4 as a conventional example. Is. The vibration suppressing circuit device shown in FIG. 1 comprises a pilot operated on-off valve 21 which connects the main pipes 3 and 4 with each other, and a pilot operated two-way valve 22 which controls the on-off valve 21. The on-off valve 21 connecting the main pipe lines 3 and 4 is normally offset to the closed position by the spring 23.

The on-off valve 21 is controlled by a pilot operated two-way valve 22 connected by a pilot line 24. The pilot ports 22a and 22b of the two-way valve 22 are connected upstream and downstream of the slow return valve 11, and when the upstream and downstream pilot pressures are equal, the pilot line of the on-off valve 21 is set by the offset of the spring 25 as shown in the figure. The tank 24 and the tank 26 communicate with each other.

On the other hand, when the spool of the pilot operated two-way valve 22 moves and the pilot pipes 9 and 24 communicate with each other, pilot pressure is applied to the on-off valve 21 so that the two main pipes 3 and 4 communicate with each other. Is configured. Therefore, when the pilot operated two-way valve 22 moves to the d position, the spring force of the spring 23 is smaller than the spring force of the spring 25 so that the on-off valve 21 is switched to the open position b.

Next, the operation of the vibration suppression circuit device will be described. When the operating lever 7 is rotated to the right side in the figure, pilot pressure is applied to the directional control valve 5 through the slow return valve 11, the directional control valve 5 is switched to the L position, and the hydraulic pump 2 and the hydraulic cylinder 1 are on the piston rod side. The hydraulic chamber 1a is connected and the hydraulic cylinder 1 contracts. At this time, the pilot pressures applied to the two pilot ports 22a and 22b of the pilot operation two-way valve 22 are equal, the spool is at the offset position c, and the on-off valve 21 maintains the closed position a.

Next, when the operation lever 7 is returned to the neutral position, the pilot pressure oil added to the direction control valve 5 returns to the tank 26 via the throttle 11a of the slow return valve 11. At this time, the reduction rate of the pilot pressure P _U on the tank side is faster than the reduction rate of the pilot pressure P _L on the side of the directional control valve 5 due to the flow rate limiting action of the throttle 11a, and a pressure difference occurs. Due to this pressure difference ΔP = P _L −P _U , the spool of the pilot operated two-way valve 22 moves to the d position, the pilot line 9 and the pilot port of the on-off valve 21 communicate with each other, and the on-off valve 21 opens to the open position b. Switch to. As a result, the piston rod side oil chamber 1a and the bottom side oil chamber 1b of the hydraulic cylinder 1 are in communication with each other, the pressures of the two oil chambers 1a and 1b are substantially balanced, and the reaction force generated by the pressure imbalance is generated. Is reduced and the generation of vibration is suppressed.

The on-time of the on-off valve 21 can be adjusted by adjusting the spring 25 of the pilot operated two-way valve 22 and setting an arbitrary operating point for the pilot pressure P _L. The flow rate bypassed between the two main pipelines 3 and 4 is set by the on-time of the on-off valve 21 and the opening area. After the set ON time elapses, the pilot operated two-way valve 22 returns to the c position, the opening / closing valve 21 becomes the closed position a, and the piston rod 1c of the hydraulic cylinder 1 stops smoothly.

FIG. 2 shows another embodiment, in which the pilot pressure supplied to the on-off valve 21 via the pilot operated two-way valve 22 is directly supplied from the pilot hydraulic pump 8. The vibration suppression circuit device shown in FIG. 1 and FIG. 2 operates when contraction of the hydraulic cylinder 1 is stopped, but the pilot operated two-way valve 22 is also provided in the other pilot pipe line 10 to be symmetrically configured. However, by connecting the two two-way valves and the open / close valve via the shuttle valve, vibration can be suppressed even when the extension operation is stopped.

FIG. 3 shows still another embodiment, in which the slow return valves 11 and 12 provided on both the contraction side and extension side pilot conduits 9 and 10 have upstream and downstream sides of throttles 11a and 12a. And shuttle valves 27 and 28, respectively. The pilot pressure in the contraction side pilot conduit 9 or the expansion side pilot conduit 10 is selectively supplied to the pilot-operated two-way valve 22 via the shuttle valves 27 and 28, so that the hydraulic cylinder 1 expands when the compression stops. The vibration suppressing operation is performed at any time of stop.

The present invention can be modified in various ways without departing from the spirit of the invention, and it goes without saying that the technical scope of the invention extends to those modifications.

[0019]

[Effect of the device]

 As described in detail in the above-mentioned embodiment, this invention makes the two main pipe lines communicate with each other when the operation of the hydraulic actuator is stopped to prevent the pressure difference from being generated. Therefore, a sudden increase in the pressure in the oil chamber on the braking side and the main pipeline due to the inertia of the boom of the construction machine driven by the hydraulic actuator is suppressed, the reaction force is reduced, and the vibration of the hydraulic actuator and the machine body is reduced. Suppress. Therefore, the shift of the stop position of the boom or the like in response to the stop instruction from the operation lever or the like is reduced, and the operability is improved. In addition, since the vibration is reduced, the physical fatigue of the operator is significantly reduced, which contributes to the improvement of workability.

[Brief description of drawings]

FIG. 1 is a hydraulic actuator drive circuit diagram provided with a vibration suppression circuit device of the present invention.

FIG. 2 is a hydraulic actuator drive circuit diagram showing another embodiment.

FIG. 3 is a hydraulic actuator drive circuit diagram showing another embodiment.

FIG. 4 is a conventional hydraulic actuator drive circuit diagram.

FIG. 5 is a timing chart of each part by a conventional hydraulic actuator drive circuit.

[Explanation of symbols]

 1 Boom Cylinder 2 Hydraulic Pump 3, 4 Main Line 5 Pilot Operating Direction Control Valve 6 Pilot Operating Section 8 Pilot Hydraulic Pump 9, 10 Pilot Line 11, 12 Slow Return Valve 11a, 12a Throttle 21 Open / Close Valve 22 Pilot Operating Two-way Valve

Claims (1)

[Scope of utility model registration request] 1. In a hydraulic machine for controlling a hydraulic actuator by a pilot operated directional control valve, a flow rate control valve is provided in a pilot line connecting a pilot operated part and the directional control valve, and a pilot operated two-way valve is provided. Pilot ports are connected respectively before and after the flow control valve, and two main pipes connecting the hydraulic actuator and the directional control valve are connected by an opening / closing valve, and the opening / closing valve is connected by the pilot operated two-way valve. A vibration suppressing circuit device for a hydraulic actuator, which is a hydraulic circuit to be controlled and is configured such that the pilot operated two-way valve opens the opening / closing valve when the pilot pressure of the directional control valve decreases.