JPH10331802A - Start forecasting device for double-acting hydraulic actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inform an operator of the state just before the starting of a double- acting hydraulic actuator by the flowing sound of hydraulic oil. SOLUTION: This device is constructed to install an energizing power changing means to change energizing power for close by a spring means 6 to two stages; high and low on the spring means 6 of a flow control valve 5. Also a control means to switch the energizing power changing means to a high energizing power side when the pilot pressure of a direction change-over valve 4 is received and the received pilot pressure becomes start forecasting pressure just before reaching sufficient pressure to connect P port and AB port by the direction change-over valve 4, and to change the energizing power changing means to a low energizing power side when it is lower than the start forecasting pressure, is attached.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-acting hydraulic actuator startup prediction device.

[0002]

2. Description of the Related Art Conventionally, a hydraulic circuit for driving a double-acting hydraulic actuator has a P port connected to a pump oil passage 1, a T port connected to a tank oil passage 2, and a double-acting hydraulic circuit, as shown in FIG. A pair of oil supply / discharge passages 3a, 3 of the actuator 3
b, a four-way, three-position, double-pilot operated directional control valve 4 having A and B ports respectively connected to b, and having a neutral position O where the A and B ports are connected to the T port;
It is interposed between the pump oil passage 1 and the tank oil passage 2 and is urged to open by the hydraulic pressure supplied to the P port, and is urged to close by the spring means 6 and the hydraulic pressure of the A and B ports, and the hydraulic pressure of the P port Has a flow control valve 5 configured to release the oil in the pump oil passage 1 to the tank oil passage 2 when the oil pressure of the A and B ports becomes higher than a predetermined value.

In FIG. 3, reference numeral 7 denotes a pilot pressure generator for controlling a pilot pressure applied to a pair of pilot oil passages 8 and 9 of a directional control valve. The pilot pressure corresponding to the tilt amount is caused to act on the pilot oil passage 8 by performing the tilt operation to the pilot oil passage 8, and the pilot pressure corresponding to the tilt amount is controlled by performing the tilt operation from the neutral position Q to the B direction from the operation lever 7a. It acts on the road 9.

The hydraulic circuit for driving a double-acting hydraulic actuator configured as described above tilts the operating lever 7a of the pilot pressure generating device 7 to tilt the pilot oil passages 8, 9 according to the tilting operation direction. The pilot pressure according to the amount is applied, and the directional control valve 4
, The double-acting hydraulic actuator 3 can be driven in an arbitrary direction and at an arbitrary speed, and while the double-acting hydraulic actuator 3 is being driven, the flow control valve 5
Since the hydraulic pressure at the P port is maintained at a predetermined value with respect to the hydraulic pressures at the A and B ports, when the switching amount of the directional control valve 4 is determined, the amount of hydraulic oil flowing from the P port of the directional switching valve to the A or B port, that is, The drive speed of the hydraulic actuator 3 can be kept constant regardless of the magnitude of the load of the hydraulic actuator 3.

[0005] This type of hydraulic circuit for driving a double-acting hydraulic actuator is frequently used for driving a double-acting hydraulic actuator for a mobile crane, an aerial work vehicle or the like.

[0006]

The above-mentioned hydraulic circuit for driving the double-acting hydraulic actuator is provided with a direction switching valve 4 which is switched through a pilot pressure generating device 7.
However, the double-acting hydraulic actuator 3 is started by connecting the P port to the A or B port and the hydraulic oil starts flowing during this time. The operator operating the pilot pressure generating device 7 knows the time. Was difficult.

That is, when it is necessary to accurately grasp the activation of the double-acting hydraulic actuator 3 such as when the double-acting hydraulic actuator 3 is driven at a very low speed or when it is driven in a very small amount, the operator operates the pilot pressure generating device 7. It is necessary to watch the actuation of the double-acting hydraulic actuator 3 while tilting the operating lever 7a at a very low speed. On the other hand, the operating lever 7a has a play in the interlocking relationship between the operating lever 7a and the direction switching valve 4. Since there is a play based on the dead zone based on the dead zone based on the amount of operation required to connect the directional switching valve 4 to its P port and the A or B port, the operator needs to operate the operation lever 7a throughout the play. It is necessary to pay attention to the start of the double-acting hydraulic actuator 3 and to pay attention to the operator. There is a problem in that.

[0008]

The start-up prediction device for a double-acting hydraulic actuator according to the present invention adds a part of the configuration to the above-described hydraulic circuit for driving the double-acting hydraulic actuator, thereby starting the double-acting hydraulic actuator 3. It is an object of the present invention to provide a start-up prediction device for a double-acting hydraulic actuator capable of notifying an operator of the immediately preceding operation by a flowing sound of hydraulic oil, and has the following configuration.

It has a P port connected to the pump oil passage 1, a T port connected to the tank oil passage 2, and A and B ports connected to the double-acting hydraulic actuator 3, with the AB port connected to the T port. A four-way three-position type double pilot operated type directional control valve 4 having a neutral position O and a pump oil passage 1 and a tank oil passage 2 which are opened by hydraulic pressure supplied to a P port. Biased spring means 6
And a flow control valve 5 configured to release the oil in the pump oil passage 1 to the tank oil passage 2 when the oil pressure in the P port becomes higher than the oil pressure in the AB port by a predetermined value or more when the oil pressure in the P port becomes higher than the oil pressure in the AB port. In the hydraulic circuit for driving a double-acting hydraulic actuator,
A biasing force changing means for switching the closing biasing force of the spring means 6 between two levels is attached, and the pilot pressure of the directional control valve 4 is received, and the pilot pressure related to the reception is applied to the directional control valve 4 to generate P. Port and A
When the starting forecast pressure becomes just before the pressure sufficient to connect the B port is reached, the urging force changing unit is switched to the high urging force side, and when the starting forecast pressure is lower than the starting forecast pressure, the urging force changing unit is switched to the low urging force side. A start-up forecasting device for a double-acting hydraulic actuator, comprising control means.

[0010]

According to the above construction, the pilot pressure acting on the directional control valve 4 is reduced to the start forecast pressure set just before the directional control valve 4 is operated to connect the P port to the A port or the B port. When reaching, the urging force changing means switches the urging force of the spring means 6 of the flow control valve 5 (the closing urging force of the flow control valve 5) to the high urging force side, and flows through the flow control valve 5 accordingly. Since the flowing noise of the hydraulic oil increases, the operator can grasp immediately before the start of the double-acting hydraulic actuator 3 by the increase of the flowing noise.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In describing an embodiment of the present invention, a hydraulic circuit for driving a double-acting hydraulic actuator shown and described in FIG. Therefore, the same parts as those of the present invention and those of the related art are denoted by the same reference numerals and detailed description thereof will be omitted, and the following embodiments of the present invention will be described.

FIG. 1 shows a hydraulic circuit for driving a double-acting hydraulic actuator according to an embodiment of the present invention. This hydraulic circuit is provided with an urging force changing means for switching the closing urging force of the spring means 6 of the flow control valve 5 between high and low stages in the hydraulic circuit of FIG. Hereinafter, the configuration of the urging force changing unit will be described.

Reference numeral 13 denotes a pilot switching valve, which is switched by the hydraulic pressure of the pilot oil passage 12 from the shuttle valve 11 connected to the pilot oil passages 8 and 9 of the direction switching valve 4. Reference numeral 15 denotes a pilot piston, which changes its position by the pressure of a pilot oil passage 14 connected to the pilot switching valve 13, thereby switching the closing urging force of the spring means 6 between high and low. The pilot oil passage 14 is selectively connected to a tank oil passage or a hydraulic pressure source at the pilot switching valve 13.

The operation of the above configuration will be described. When the pilot pressure is generated in the pilot oil passage 8 or 9 by operating the operation lever 7 a of the pilot pressure generator 7, the pilot pressure is transmitted via the shuttle valve 11 to the pilot oil passage 1.
It is led to 2. The pilot pressure in the pilot oil passage 8 or 9 acting on the directional control valve 4
When the starting forecast pressure set immediately before the port and the A or B port are sufficiently connected is reached, the pilot switching valve 13 is switched from the illustrated state to the right. Then, the pressure from the pressure source connected to the pilot switching valve 13 is guided to the pilot oil passage 14 and the pilot piston 1
5 is switched to the high bias position.

As described above, the urging force of the spring means 6 of the flow control valve 5 (the closing urging force of the flow control valve 5) switches to the high urging force side, and flows through the flow control valve 5 accordingly. Since the flowing noise of the hydraulic oil increases, the operator can grasp immediately before the start of the double-acting hydraulic actuator 3 by the increase of the flowing noise.

FIG. 2 shows a drive hydraulic circuit having two double-acting hydraulic actuators according to another embodiment. The lower half relates to the first actuator, the upper half the second
Of the actuator. The pilot pressure generating means is 7 and 27, and the flow control valve is 17
And 37, and switching valves 16 and 36 are provided, respectively, and the corresponding first actuator 3 or second actuator 23 is driven by operating each operation lever 7a or 27a. I have.

First, the configuration and operation of the hydraulic circuit relating to the first actuator will be described. 17 is interposed between the pump oil passage 1 and the bypass oil passage 18 and is urged to open by the hydraulic pressure supplied to the P port, and the spring means 19 is provided.
When the oil pressure at the P port becomes higher than the oil pressure at the A and B ports by a predetermined value or more, the oil in the pump oil passage 1 is released to the bypass oil passage 18 when the oil pressure at the P port becomes higher than the oil pressure at the A and B ports. Flow control valve. Reference numeral 16 denotes a direction switching valve which is operated by the pilot oil passage 8 or 9 from the pilot pressure generator 7, and is a P port connected to the oil passage 21 from the flow control valve 17.
A neutral port having a T port connected to the tank circuit 22 and A and B ports connected to a pair of supply / discharge oil passages 3a and 3b of the double-acting hydraulic actuator 3, wherein the A and B ports are connected to the T port. It has a position O.

Reference numeral 13 denotes a pilot switching valve, which is switched by the hydraulic pressure of the pilot oil passage 12 from the shuttle valve 11 connected to the pilot oil passages 8 and 9 of the direction switching valve 16. Reference numeral 20 denotes a pilot piston, which changes its position by the pressure of a pilot oil passage 14 connected to the pilot switching valve 13, thereby switching the closing urging force of the spring means 19 between two levels. The pilot oil passage 14 is provided with the pilot switching valve 13.
Is selectively connected to a tank oil passage or a hydraulic pressure source.

The hydraulic circuit for driving a double-acting hydraulic actuator configured as described above tilts the operation lever 7a of the pilot pressure generating device 7 to tilt the pilot oil passages 8 and 9 in accordance with the tilt operation direction. The pilot pressure according to the amount is applied, and the directional control valve 1
6, the double-acting hydraulic actuator 3 can be driven in an arbitrary direction and at an arbitrary speed.
Keeps the hydraulic pressure at the P port at a predetermined value with respect to the hydraulic pressure at the A and B ports. Therefore, when the switching amount of the directional control valve 16 is determined, the hydraulic oil flowing from the P port of the directional control valve to the A or B port The amount, that is, the driving speed of the hydraulic actuator 3 can be kept constant regardless of the magnitude of the load of the hydraulic actuator 3.

Further, when the pilot pressure is generated in the pilot oil passage 8 or 9 by operating the operating lever 7a of the pilot pressure generating device 7, the pilot pressure is applied to the shuttle valve 11.
To the pilot oil passage 12. Direction switching valve 1
When the pilot oil pressure in the pilot oil passage 8 or 9 acting on the valve 6 reaches the start forecast pressure set just before the directional switching valve 16 is connected to connect the P port to the A or B port, the pilot switching valve 13 is switched from the state shown to the right. Then, the pressure from the pressure source connected to the pilot switching valve 13 is guided to the pilot oil passage 14, and the pilot piston 20 is switched to the high urging position.

As described above, the urging force of the spring means 19 of the flow control valve 17 (the flow control valve 1)
7) is switched to the high urging force side, and the flow noise of the hydraulic oil flowing through the flow control valve 17 increases accordingly. It is possible to know immediately before the activation of the hydraulic actuator 3.

The structure and operation of the hydraulic circuit relating to the second actuator are the same as those of the first actuator, and therefore will not be described.

[0023]

As described above, according to the start-up predicting apparatus for a double-acting hydraulic actuator according to the present invention, when it is necessary to accurately grasp the start-up of the double-acting hydraulic actuator, it is necessary to operate the pilot pressure generating apparatus as in the prior art. Even if the operation lever is not tilted at a low speed and the double-acting hydraulic actuator 7 is not watched over the entire dead zone of the lever, the operator gazes at the startup of the double-acting hydraulic actuator only after grasping immediately before the start by the flowing sound of the hydraulic oil. However, since the operation lever only needs to be tilted at a very low speed, there is an effect that the labor required for the operator is greatly reduced.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit according to the present invention.

FIG. 2 is a hydraulic circuit showing another embodiment according to the present invention.

FIG. 3 is a hydraulic circuit of a conventional double-acting hydraulic actuator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Pump oil passage 2 Tank oil passage 3 Double-acting hydraulic actuator P P port T T port A A port B B port O Neutral position 4 Direction switching valve (4 direction 3 position type double pilot operated type) 5 Flow control valve 6 Spring Means 7 Pilot pressure generator 7a Operating lever 8 Pilot oil passage 9 Pilot oil passage 13 Pilot switching valve 15 Pilot piston

Claims (2)

[Claims] A P port connected to a pump oil passage, a T port connected to a tank oil passage, and A and B ports connected to a double-acting hydraulic actuator, wherein the AB port is a T port. A four-way three-position type double pilot operated directional control valve 4 having a neutral position O connected to the pump oil passage 1 and the tank oil passage 2 and hydraulic pressure supplied to the P port The spring means 6
And a flow control valve 5 configured to release the oil in the pump oil passage 1 to the tank oil passage 2 when the oil pressure in the P port becomes higher than the oil pressure in the AB port by a predetermined value or more when the oil pressure in the P port becomes higher than the oil pressure in the AB port. In the hydraulic circuit for driving a double-acting hydraulic actuator,
A biasing force changing means for switching the closing biasing force of the spring means 6 between two levels is attached, and the pilot pressure of the directional control valve 4 is received, and the pilot pressure related to the reception is applied to the directional control valve 4 to generate P. Port and A
When the starting forecast pressure becomes just before the pressure sufficient to connect the B port is reached, the urging force changing unit is switched to the high urging force side, and when the starting forecast pressure is lower than the starting forecast pressure, the urging force changing unit is switched to the low urging force side. A start-up forecasting device for a double-acting hydraulic actuator, comprising control means. 2. The urging force changing means is associated with the spring means 6 so as to increase the closing urging force of the spring means 6 when the pressure oil is supplied and to decrease the closing urging force of the spring means 6 when the pressure oil is discharged. A pilot switching valve 13 that is switched by the pilot pressure of the direction switching valve 4.
The pilot pressure for switching the directional control valve 4 is switched when the directional control valve 4 reaches a start forecast pressure just before reaching a pressure sufficient to connect the pump oil passage to the AB port. A pilot switching valve 13 configured to supply hydraulic pressure from a hydraulic pressure source to the pilot piston 15 and to switch the pressure oil from the pilot piston 15 to a tank oil passage when the pilot pressure is equal to or lower than the startup forecast pressure. 2. The start-up prediction device for a double-acting hydraulic actuator according to claim 1, wherein: