JPH0514804B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention has a pilot-operated directional valve between a control valve and an actuator, and controls the directional valve and the control valve to The present invention relates to a control device for a hydraulic circuit that controls the speed of an actuator according to a flow rate.

[Conventional technology]

Conventionally, as a hydraulic circuit for controlling the speed of an actuator, there is a type in which a pilot-operated directional switching valve is provided between a control valve and an actuator, as shown in, for example, Japanese Patent Laid-Open No. 57-154505.

A pilot-operated directional control valve in this type of hydraulic circuit is provided to prevent the driven object from falling due to damage to the pipe line or the like. As an example of the use of this type of hydraulic circuit, after switching the aforementioned pilot-operated directional control valve to the open state, the control valve is operated to supply pressure oil from the hydraulic source to the actuator to turn the actuator. It is possible to control acceleration.

[Problem that the invention seeks to solve]

In the above conventional example, when the inlet port and outlet port of the pilot operated directional control valve are connected in a state where there is a pressure difference before and after the pilot operated directional control valve, the high pressure side immediately Oil flows to the low pressure side and a shock occurs. In other words, even if the control valve is operated slowly in order to quietly accelerate the load with the actuator, the inertia of the load and the oil in the piping will be affected due to the shock during control of the pilot-operated directional valve mentioned above. There was a problem that the load vibrated due to the spring effect due to compressibility.

The present invention has been made based on the above-mentioned matters, and there is no shock due to switching of the pilot operated directional control valve, and when a signal to operate the control valve is inputted by the operating lever, the pilot operated directional control valve is immediately switched to the pilot operated directional control valve. It is an object of the present invention to provide a control device for a hydraulic circuit that can smoothly accelerate a load even when a directional switching valve is switched.

[Means for solving problems]

The above objects of the present invention include: a pump that supplies pressure oil for actuator operation; a control valve that controls the flow of the pressure oil; and a tank into which oil discharged from the actuator is guided by the control valve. The hydraulic circuit includes a directional switching valve that is interposed between the control valve and the actuator and connects and disconnects the flow of pressure oil supplied from the control valve to the actuator, wherein the directional switching valve and the A control device for a hydraulic circuit that switches and controls a control valve based on a signal from an operating lever, comprising: a pressure detector provided in each of an upstream pipe line and a downstream pipe line of the directional switching valve; and an actuation of the operating lever. a lever operation detector for detecting the operation lever; and when receiving a control lever non-operation signal from the lever operation detector, the pressure value before and after the direction switching valve detected by the pressure detector is used to switch the direction. Calculates a command value to the control valve to reduce the difference in actuator holding force before and after the valve, outputs this command value to the control valve, and receives a control lever actuation signal from the lever actuation detector. This is achieved by comprising a control means for outputting a value corresponding to the operation amount of the operation lever to the control valve.

[Effect]

When the operating lever is not operated, the control valve is operated to reduce the difference in actuator holding force before and after the directional control valve using the pressure detected by the pressure sensor before and after the directional control valve. Since the shock caused by switching is adjusted in advance, even if the operating lever is operated and the immediate directional switching valve is switched, the shock at the time of switching can be reduced.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the device of the present invention, in which 1 is a hydraulic pump, 2 is a relief valve, 3 is a control valve such as an electro-hydraulic servo valve, and 4 is an actuator such as a cylinder. , 5
Reference numerals a and 5b designate external pilot operated directional control valves provided in the conduit between the control valve 3 and the actuator 4, and are comprised of, for example, pilot operated check valves. Reference numeral 6 indicates an on/off switching valve for switching the pilot oil pressure of the directional switching valves 5a and 5b, 7 and 8 pressure detectors respectively provided in the inlet port side pipe line and the outlet port side pipe line of the directional switching valve 5a, and 9 and 10 directional control valves. 11 is an operating lever; 11A is a lever operation detector; 12 is a control device; An on signal or an off signal is output to the on/off switching valve 6 according to the manipulated variable and the pressure values of the pressure detectors 7 to 10, and a current I is output to the control valve 3. 13 is an oil tank.

As shown in FIG. 2, the control device 12 described above has the following functions:
For example, it is composed of a digital arithmetic unit and an analog circuit, and includes an A/D converter 12A that converts an analog signal into a digital signal, a central processing unit 12B that performs various controls and arithmetic processing, and a control means program and predetermined Memory 12 in which the functional relationship of
C, a driver circuit 12D that outputs the control content to the on/off switching valve 6, a D/A converter 12E that converts the digital signal that is the output of the control content into an analog signal, and a control circuit that converts the voltage signal into a current signal. It also includes a servo amplifier 12F that outputs to the valve 3.

Next, the operation of one embodiment of the apparatus of the present invention described above will be explained using the flowchart shown in FIG.

First, as shown in step 70, the operating amount X _L of the operating lever 11 is detected by the pressure detector 7 to the central processing unit 12B via the A/D converter 12A of the control device 12 shown in FIG. Pressure P _A on the inlet port side of the directional control valve 5a, pressure P _H on the outlet port side of the directional control valve 5a detected by the pressure detector 8
Directional switching valve 5b detected by pressure detector 9
The pressure P _B on the inlet port side of the directional control valve 5b and the pressure P _R on the outlet port side of the directional control valve 5b detected by the pressure detector 10 are read. Next, as shown in step 71, the central processing section 12B operates the operating lever 11.
is being manipulated, that is, the amount of manipulation X _L
It is determined whether or not exceeds the range of servo valve current command value X=0. At this time, the operating lever 11
If it is determined that the is not being operated, proceed to step 7.
2, from the central processing unit 12B to the driver circuit 1
An off signal is output to the switching valve 6 via 2D. This keeps the directional control valves 5a, 5b in the closed state shown in FIG.

Next, the process moves to step 73, and the directional control valves 5a, 5b are
Performs pressure matching control to reduce the pressure difference before and after the The content of this pressure matching control will be explained in detail later.

Furthermore, if it is determined in step 71 that the operating lever 11 is being operated, the process moves to step 74. In step 64, an ON signal is output from the central processing section 12B to the switching valve 6 via the driver circuit 12D. As a result, the switching valve 6 is switched to the left from the state shown in FIG. 1, and the directional switching valves 5a and 5b are brought into the open state.

Next, as shown in step 75, the central processing unit 12
B is the operating lever 1 stored in the memory 12C.
From the functional relationship between the manipulated variable X _L and the servo valve current command value X, a process is performed to select a specific value X _{0 corresponding} to the manipulated variable X _L , and this
It is set to C. After steps 73 and 75, the process moves to step 76, where the servo valve current command value X is output from the central processing section 12B to the D/A converter 12E. Then, as shown in step 77, the D/A
After the converter 12E converts the servo valve current command value X, which is a digital signal, into an analog voltage signal V, the servo amplifier 12F converts the voltage signal V into a current signal I, and the servo current I is output to the control valve 3. Ru. The control valve 3 controls the flow rate according to this servo current I.

FIG. 4 is a flowchart showing an example of a control procedure for pressure matching control used in the apparatus of the present invention. In this embodiment, the thrust force applied to the cylinder 4 in the state shown in Fig. 1, that is, the effective area on the head side of the cylinder 4 is A _H and the effective area on the rod side is A _R.
Then, the cylinder thrust force f is f=A _H・P _H −A _R・P _R (1). The inlet port pressures P _A and P _B of the directional control valves 5a and 5b are adjusted so that the pressure corresponds to this thrust force f.
control. By carrying out this control, when the directional control valves 5a and 5b are switched, a sudden change in thrust force does not occur in the cylinder 4, so that the shock can naturally be reduced.

First, in step 80, pressures P _H , _PR , _PA , and _PB are read through the A/D converter 12A. Next, in step 81, the outlet port pressure of the directional control valve 5a is
By multiplying P _H by the head side area A _H of the cylinder 4, the force applied to the head side of the cylinder 4 is calculated, and the value F _H is stored in the memory 12C. Then, proceed to step 82, F _R =A _R *P _R
By performing the calculation, the force applied to the rod side of the cylinder 4 is calculated, and the value F _R is stored in the memory 12C. Then, in step 83, F _A =
A _H *P _A is calculated and the value is stored in the memory 12C. In step 84, the calculation F _B =A _R *P _B is similarly performed and the value is stored in the memory 12C. Then, in step 85, the thrust force applied to the cylinder 4 and the inlet port pressure of the directional control valves 5a and 5b are
Take the difference in thrust calculated from P _A and P _B , and the difference ΔF
is stored in the memory 12C. Next, the process moves to step 86, where the central processing unit 12B multiplies the thrust difference ΔF stored in the memory 12C by a preset coefficient _K3 , and the calculation result is _X3.
Set to the servo valve current command value X. This step 80~
By repeating step 86, the directional control valves 5a, 5b
The inlet port pressures P _A and P _B can be made close to the pressure corresponding to the thrust force f applied to the cylinder 4.

In the above embodiment, a digital arithmetic unit and an analog circuit are used as the control device 12, but the control device 12 can also be constructed entirely of analog circuits.

[Effects of the Invention] As described above, according to the present invention, the switching shock when opening the directional control valve can be reduced, and when the operating lever is operated, the load can be smoothly accelerated, improving operability. Able to construct a good machine.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the device of the present invention, Fig. 2 is a circuit diagram showing an example of a control device constituting the device of the present invention, and Fig. 3 is a flowchart showing the control procedure of the present invention. 4 are flowcharts of the control procedure for pressure matching control used in the present invention. 3...Control valve, 4...Cylinder, 5a, 5b...
...Directional switching valve, 6...On-off switching valve, 7-10
...Pressure detector, 11...Operation lever, 11A...
...Lever operation detector, 12...Control device.

Claims (1)

[Claims] 1 A pump that supplies pressure oil for the actuator to operate, a control valve that controls the flow of the pressure oil,
A tank through which oil discharged from the actuator is guided by the control valve, and a direction that is interposed between the control valve and the actuator and connects or disconnects the flow of pressure oil supplied from the control valve to the actuator. A control device for a hydraulic circuit that switches and controls the directional switching valve and the control valve based on a signal from an operating lever, wherein the directional switching valve has an upstream pipe line and a downstream side of the directional switching valve. A pressure detector provided in each of the pipe lines,
a lever operation detector that detects the operation of the operating lever; and when receiving an operation lever non-operation signal from the lever operation detector, a pressure value before and after the directional control valve detected by the pressure detector; is used to calculate a command value to the control valve to reduce the difference in actuator holding force before and after the directional switching valve, output this command value to the control valve, and output a control lever actuation signal from the lever actuation detector. and a control means for outputting a value corresponding to the operation amount of the operation lever to the control valve when the control valve is receiving the operation amount.