JPH0514121B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention has a communication valve that connects and disconnects the flow of pressure oil between a control valve and an actuator, and controls the operation of the communication valve and the control valve. The present invention relates to a control device for a hydraulic circuit that controls the speed of an actuator depending on the flow rate through a valve.

[Background of the invention]

Conventionally, as a hydraulic circuit for controlling the speed of an actuator, there is a type in which a pilot-operated check 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 check valve in this type of hydraulic circuit is installed to prevent a driven object from falling due to damage to a 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. Acceleration control is possible, but if the inlet port and outlet port of the pilot operated check valve are connected in a state where there is a pressure difference before and after the pilot operated check valve, the Oil flows from the high pressure side to the low pressure side, creating a shock. 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 check valve mentioned above. Due to the spring effect due to compressibility,
There was a problem with the load vibrating.

[Purpose of the invention]

The present invention has been made based on the above-mentioned problems, and an object of the present invention is to provide a hydraulic circuit control device that can reduce the shock caused by switching a pilot-operated check valve and smoothly accelerate a load.

[Summary of the invention]

In order to achieve the above object, the present invention provides a pump that supplies pressure oil for actuator operation, a control valve that controls the flow of the pressure oil, and a control valve that controls the oil discharged from the actuator. A hydraulic circuit comprising: a tank guided by the control valve; and a communication valve, which is provided on a pipe connecting the control valve and the actuator, and connects and disconnects the flow of pressure oil supplied from the control valve to the actuator, A control device for a hydraulic circuit that controls the operation of the control valve and the communication valve, comprising pressure detection means provided in each of an upstream pipe line and a downstream pipe line of the communication valve, and these pressure detection means. calculates a command value to the control valve for reducing the difference in actuator holding force before and after the communication valve using the pressure values before and after the communication valve detected by the communication valve, and outputs this command value to the control valve. It is equipped with a control means to

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 3 are explanatory diagrams of an embodiment of a control device for a hydraulic circuit according to the present invention. FIG. 1 is a configuration diagram showing the configuration of this embodiment, and FIG. FIG. 3 is a block diagram showing the configuration and a flowchart showing the flow of processing by the control device.

As shown in FIG. 1, this first embodiment includes a hydraulic pump 1, an actuator such as a hydraulic cylinder 4 operated by pressure oil supplied from the hydraulic pump 1, and a control system for guiding pressure oil to the hydraulic cylinder 4. A valve such as an electrohydraulic servo valve (hereinafter referred to as a servo valve) 3, a communication valve provided on a pipe between the servo valve 3 and the hydraulic cylinder 4, such as a pilot operated check valve (hereinafter referred to as a check valve) 5a, 5b, an on/off switching valve 6 for switching the pilot oil pressure to the check valves 5a, 5b, and pressure detection means provided on the input port side pipe line and the output side pipe line of the check valves 5a, 5b, that is, pressure detection means. Vessels 7, 8, 9, 10
inputs the operating amount of the operating lever 11 and the pressure signals from the pressure detectors 7, 8, 9, and 10, outputs a signal corresponding to these values to the on/off switching valve 6, and also outputs a current to the servo valve 3. A control device 12 is provided as a control means for outputting a signal. Further, the discharge pressure of the hydraulic oil sucked from the oil tank 13 by the hydraulic pump 1 is suppressed to a predetermined pressure or less by the relief valve 2. Further, the hydraulic cylinder 4 is connected to a working member 14 such as an arm.

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 servo circuit that converts the voltage signal into a current signal. It also includes a servo amplifier 12F that outputs to the valve 13.

Next, the operation of one embodiment of the above-mentioned hydraulic circuit control device according to the present invention will be explained using the flowchart shown in FIG.

First, as shown in step 40, 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. The pressure P _A on the inlet port side of the check valve 5a, the pressure P H on the outlet port side of the check valve 5a detected by the pressure detector 8, and the pressure P _H on the outlet port side of the check valve 5a detected by the pressure detector 9. The pressure P _B on the inlet port side of the check valve 5b and the pressure P _R on the outlet port side of the check valve 5b detected by the pressure detector 10 are read. Next, as shown in step 41, the central processing unit 12B determines whether the operating lever 11 is being operated, that is, whether the operating amount X _L exceeds the range of the servo valve current command value X=0. At this time, if it is determined that the operating lever 11 is not operated, the process moves to step 42, and an OFF signal is output from the central processing section 12B to the on/off switching valve 6 via the driver circuit 12D. This keeps the check valves 5a, 5b in the closed state shown in FIG. 1. In addition, in step 42, the on/off switching valve 6
is closed, and the OR signal is sent to memory 1.
Store it in 2C. Next, as shown in step 43, the memory 12C performs a process of setting the current command value X to the servo valve 3 to 0 in response to a command from the central processing unit 12B.

If it is determined in step 41 that the operating lever 11 is being operated, the process moves to step 44, and the on/off switching valve 6 is turned ON based on the information in step 42 and step 46, which will be described later. Determine whether it is in the open state. At this time,
If it is determined that the switching valve 6 is not turned on, the process moves to step 45, and pressure matching control is performed to reduce the pressure difference across the check valves 5a and 5b. The content of this pressure matching control will be explained in detail later. After completing step 45, the process moves to step 46. Further, if it is determined in step 44 that the on/off switching valve 6 is turned on, control moves to step 46.

In step 46, an ON signal is output from the central processing unit 12B to the on/off switching valve 6 via the driver circuit 12D. As a result, the on/off switching valve 6 is switched, and the check valves 5a and 5b are opened. Further, in step 46, the on/off switching valve 6 is turned on, and the ON signal is stored in the memory 12C. Next, as shown in step 47, the central processing unit 1
2B is a specific value X _O corresponding to the operation amount X _L based on the functional relationship between the operation amount X L of the operating lever 11 and the servo valve current command value _X stored in the memory 12C.
This X=X _O is memory 1.
It is set to 2C. And step 43 and step 47
After that, the process moves to step 48, 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 49, 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 servo valve 3. Ru. The servo valve 3 controls the flow rate according to this servo current I.

FIG. 4 is a flowchart showing a first example of a control procedure for pressure matching control by the above-described control device of the present invention. In this first embodiment, the pressure difference in the front stage of the check valve having the higher pressure among the outlet port pressures P _H and _PR of the check valves 5a and 5b is made smaller. Considering the pipe resistance, spring characteristics of hydraulic oil, internal leakage of each valve, etc., the difference in pressure between the input port side and the output port side of check valves 5a and 5b is higher on the high pressure side. This is done to make it easier for this to occur. This makes it possible to reduce the differential pressure across the check valve, which has a large pressure difference, and to reduce the shock caused when the input port and output port of the check valve communicate with each other.

First, in step 50, it is determined which of the outlet port pressures P _H and _PR of the check valves 5a and 5b is higher pressure.
At this time, if it is determined that the outlet port pressure P _H of the check valve 5a is high, the process moves to step 51, and again,
The pressures P _H and P _A are read through the A/D converter 12A. Next, as shown in step 52, the central processing unit 12B calculates the difference between the pressure P _H and the pressure P _A , and stores the value as ΔP in the memory 12C. and,
Proceeding to step 53, the central processing unit 12B calculates the pressure difference ΔP previously calculated and stored in the memory 12C.
Whether the absolute value of -ΔP- is smaller than the first pressure matching control completion judgment value ΔP _O set in advance in the memory 12C, that is, check valve 5a.
It is determined whether the pressure difference between the pressures P _H and P _A at the inlet and outlet ports of is smaller than the specified value. At this time, if it is determined that the pressure difference -ΔP- is smaller than the specified value ΔP _O , the program exits from this pressure matching control procedure and returns to the original program. Further, if it is determined in step 53 that the pressure difference -ΔP- is larger than the specified value, the process moves to step 54, and the pressure difference ΔP is preset to the pressure difference ΔP stored in the memory 12C by the central processing unit 12B. Perform the process of multiplying by the coefficient K ₁ ,
The calculation result _X1 is set as the control valve current command value X.
Then, through steps similar to steps 48 and 49 shown in FIG. 3, a current I corresponding to the calculation result _X1 is output to the control valve 3. Here, when a positive current flows through the servo valve 3, pressure oil flows into the hydraulic pipe on the check valve 5a side, and when a negative current flows, pressure oil flows into the hydraulic pipe on the check valve 5b side. Assume that pressure oil flows through the road. Then, after step 54, repeat step 5.
Return to step 1 and read the pressures P _H and P _A. This step 5
By repeating steps 1 to 54, the differential pressure across the check valve 5a becomes smaller.

In step 50 above, the outlet port pressure of the check valve 5b
If it is determined that P _R is high, proceed to step 55.
Procedure 55 similar to steps 51 to 54 regarding check valve 5b
After passing through the steps 58 to 58, the differential pressure across the check valve 5b is reduced.

FIG. 5 is a flowchart showing a second embodiment of the control procedure for pressure matching control by 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, if 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 , the cylinder thrust force is: =A _H・P _H −A _R・P _R ……(1) becomes. The inlet port pressures P _A and P _R of the check valves 5a and 5b are controlled so that the pressure corresponds to this thrust. By performing this control, the check valve 5
When a and 5b are switched, no sudden change in thrust occurs in the cylinder 4, so naturally the shock becomes smaller.

First, in step 60, the pressures P _H , _PR , _PA , and _PB are read through the A/D converter 12A. Next, in step 61, the outlet port pressure of the directional control valve 5a is
The force applied to the head side of the cylinder 4 is calculated by multiplying P _H by the head side area A _H of the cylinder 4, and the value F _H is stored in the memory 12C. Then, proceed to step 62, 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 63, F _A =
A _H *P _A is calculated and the value is stored in the memory 12C. In step 64, F _B =A _R *P _B is similarly calculated, and the value is stored in the memory 12C. Then, in step 65, the thrust force applied to the cylinder 4 and the inlet port pressure P _A of the check valves 5a, 5b,
The difference in thrust calculated from P _B is taken, and the difference ΔF is stored in the memory 12C. Next, proceed to step 66,
The central processing unit 12B first calculates and stores it in the memory 1.
Absolute value of thrust difference ΔF stored in 2C -ΔF-
is set in advance in the memory 12C.
It is determined whether the pressure matching control completion judgment value _ΔFO is smaller than the pressure matching control completion judgment value ΔFO. At this time, the difference in thrust force -ΔF-
If it is determined that is smaller than the specified value ΔF _O , the pressure matching control procedure is exited and the original program is returned. Also, in step 66, the difference in thrust force -ΔF-
If it is determined that is larger than the specified value, proceed to step 6.
7, the memory 12 is processed by the central processing unit 12B.
The thrust difference ΔF stored in C is multiplied by a preset coefficient K _Z , and the calculation result X _Z is used as the servo valve current command value X. and,
After going through steps similar to steps 48 and 49 shown in FIG. 3, a current I corresponding to the calculation result _XZ is output to the servo valve 3. By repeating these steps 60 to 67, the inlet port pressure of check valves 5a and 5b is reduced.
P _A and P _B become close to the pressure corresponding to the thrust applied to the cylinder 4.

In the first and second embodiments described above, 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.

〔Effect of the invention〕

As described above, according to the present invention, the switching shock when opening the communication valve can be reduced, so that the load can be smoothly accelerated.

[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. , FIG. 4 is a flowchart showing a first example of a control procedure for pressure matching control according to the present invention, and FIG. 5 is a flowchart showing a second example of a control procedure for pressure matching control according to the present invention. 3...Servo valve, 4...Cylinder, 5a, 5b
...Directional switching valve, 6...On-off switching valve, 7-1
0...Pressure detector, 11...Operation lever, 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,
Provided on a pipe path connecting a tank through which oil discharged from the actuator is guided by the control valve and the control valve and the actuator, and disconnecting or disconnecting the flow of pressure oil supplied from the control valve to the actuator. A hydraulic circuit comprising a communication valve, the control valve and a hydraulic circuit control device for controlling the operation of the communication valve, wherein the control valve is provided in each of an upstream pipe line and a downstream pipe line of the communication valve. and a command value to the control valve for reducing the difference in actuator holding force before and after the communication valve using the pressure detection means detected by the pressure detection means and the pressure values before and after the communication valve detected by these pressure detection means. Calculate,
A control device for a hydraulic circuit, comprising: control means for outputting the command value to the control valve.