JPH059641B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydraulic actuator control device used in material load testing machines and the like.

[Conventional technology]

Conventionally, the 7th and 8th hydraulic actuator control devices are used to control the load on a test specimen in a loading test machine for structural members for civil engineering and construction, to control the cylinder load of a hydraulic press, to control the cylinder displacement, and to control the internal pressure of a pressure vessel. The one shown in the figure is known.

This conventional structure is used in a loading test machine, that is, W is a test object, and 51 is a hydraulic cylinder with rods on both sides as a hydraulic actuator.The test object W is attached to one rod 51a of the hydraulic cylinder. Install and fix the fluid supply pipe 52 to the hydraulic cylinder.
and the return liquid pipe 53, attach the test body W to the pressure-receiving member 54, apply an appropriate load, and repeat this process to obtain a diagram of the relationship between the load and displacement of the test body W as shown in FIG. This is used for the intended test machine.

In this case, a servo valve 55 using a nozzle flapper or a spool valve, a hydraulic unit 56 as a hydraulic pressure generating element, a servo amplifier 57, a sensor mechanism 58 as a potentiometer that takes out a feedback signal, and a measuring device 5 as a load cell that measures the load.
9 as the main control element, the hydraulic unit 56 constantly feeds pressure oil to the servo valve 55, sets a target displacement as a control purpose in this case, and sends a setting signal corresponding to this target value. and the feedback signal from the sensor mechanism 58, actuate the servo valve 55 according to the control signal, and measure the load on the test body W until the set displacement as the target value in this case is reached by the measuring device 59, A relationship diagram between load and displacement can be obtained.

Incidentally, a relation diagram between load and displacement or a relation diagram between pressure and displacement may be obtained by setting the target value as load or pressure.

[Problem to be solved by the invention]

However, in the case of this conventional structure, although a certain amount of hydraulic energy is always stored, and therefore excellent in high-speed response, on the other hand, the hydraulic unit must constantly store hydraulic energy and supply it to the servo valve, resulting in power loss. In addition, by using a nozzle flapper or spool as a servo valve, the maximum controllable pressure is lower to prevent nozzle jetting and oil leakage at the spool valve, and the entire device becomes larger and manufacturing costs are high. Due to the need to improve dimensional accuracy, there are disadvantages in that dust in the oil must be controlled more strictly than in general hydraulic circuits.

[Means to solve the problem]

The present invention aims to solve these disadvantages, and its gist is to control the operating state of a hydraulic actuator by the amount of liquid supplied in the liquid supply pipe or the amount of liquid returned in the liquid return pipe. A variable discharge pump is disposed in the liquid supply pipe, a high-speed on-off valve is disposed in the return liquid pipe, and the variable discharge pump or the high-speed on-off valve is connected to the target value. A hydraulic actuator control device is characterized in that it is configured by providing an arithmetic device that makes a selection based on comparison with an actual value and operates in response to the difference.

[Effect]

The computing device selects the variable discharge pump or high-speed on-off valve by comparing the target value and the actual value, and outputs an operation signal corresponding to the difference, and this operation signal causes the variable discharge pump or high-speed on-off valve to operate. , the operating state of the hydraulic actuator is controlled.

[First Embodiment] Figures 1 to 3 show a first embodiment in which the present invention is used in a loading test machine, in which 1 is a hydraulic actuator;
In this case, a hydraulic cylinder is used, and the test body W is fixedly attached to the rod of the hydraulic cylinder, and the test body W is attached to the pressure receiving member 2.

Reference numeral 3 denotes a variable discharge amount pump, in this case an inverter-driven hydraulic pump whose pump rotation speed can be varied in accordance with the input voltage, and is arranged in the liquid supply pipe 4 to vary the amount of liquid supplied to the hydraulic actuator 1. It is something to do.

Reference numeral 5 denotes a high-speed on/off valve, which is disposed in the liquid return pipe 6 and opens and closes the valve by pulse width control (PWM) to control the amount of liquid returned to the tank 7.

Reference numeral 8 denotes a switching valve that switches the connection between the push side port a and the pull side port b of the hydraulic actuator 1, the variable discharge amount pump 3, and the high-speed on/off valve 5.

Reference numeral 9 denotes a sensor mechanism which is used for control purposes, for example, to take out the actual value of the load on the test body W as a feedback signal.

Reference numeral 10 denotes a measuring device that outputs a measurement signal of the state of the test object W, such as displacement.

Reference numeral 11 denotes a calculation device, which is constituted by a microcomputer and calculates and outputs operating signals for the variable discharge amount pump 3, the high-speed on/off valve 5, and the switching valve 8.

Since this first embodiment has the above configuration, the test specimen W
For example, when considering a load control pattern in which the load for control purposes is applied from the initial value - L ₀ (tension) to the final value + L (compression) in the required time T as shown in Fig. 4, it is The target value shown by the dashed line, which takes into account the switching time of the switching valve 8, is set, and this target value is input to the calculation device 11, and the operation control of the hydraulic actuator 1 is started, basically from point A to point C. At point, the pressure on the pull side of the hydraulic cylinder is reduced by the high-speed on-off valve 5, from point C to point D, the switching process of the switching valve 8 (control is interrupted), and from point D to point B, the pressure on the push side is increased by the variable discharge amount pump 3. The actual value of the load applied to the specimen W in each process is taken out as an actual value by the sensor mechanism 9, and the target value at that time and the feedback value are compared. In other words, when it is necessary to supply liquid to the hydraulic actuator 1, it is first determined whether the port flow path on the side to be supplied has been switched, and if it has not been switched, the switching valve 8 is switched.
The variable discharge amount pump 3 operates under control according to the difference value, and when there is no need to supply liquid to the hydraulic actuator 1 and it is necessary to return liquid from the hydraulic actuator 1 to the tank 7, the switching valve 8 is first operated. determines whether the flow path has been switched to the port on the liquid withdrawal side, and if not, switches the switching valve 8, controls the opening/closing of the high-speed on/off valve 5, and also provides feedback values as the target value and actual value. If they are the same, the comparison between the target value and the actual value will be repeated.

By setting the partial load control pattern shown in FIG. 4 as a whole according to the test content, controlling it in the same manner as above, and measuring the momentary displacement with the setting device 10, the load control pattern as shown in FIG. A relationship diagram can be obtained.

At this time, since the liquid is supplied by the variable discharge pump 3, pressurization can be controlled according to the difference between the target value and the actual value, and the hydraulic unit is constantly driven to generate and maintain pressurized liquid. There is less power loss than in the conventional configuration, and since the liquid is discharged by the opening and closing movement of the high-speed on/off valve 5, pressure reduction control can be performed well.Furthermore, the entire device can be simplified and manufacturing costs can be reduced. .

In the above embodiment, the purpose of control is load, but it can also be controlled by displacement or pressure as in the conventional structure, and in this case, a potentiometer or a pressure transducer is used as the sensor mechanism 9 for taking out the feedback value. Will.

[Second Embodiment] Figures 5 and 6 show a second embodiment in which the present invention is used to control the internal pressure of a pressure vessel in a pressure vessel tester or a processing machine using the CIP method (cold isostatic pressure processing method). 1st
In this case, a pressure vessel serving as a hydraulic actuator 1 is connected to a liquid supply line 4 and a liquid return pipe line 6, and a liquid supply line 4 is connected to a liquid supply line 4. An inverter-driven variable discharge pump 3 similar to the first embodiment is provided, and a high-speed on/off valve 5 is provided in the return liquid line 6.

That is, in this case, the switching valve 8 of the first embodiment is not provided because it is not necessary.

Reference numeral 9 denotes a sensor mechanism as a pressure sensor, which outputs a feedback signal.

Reference numeral 11 denotes an arithmetic unit which, like the first embodiment, is composed of a microcomputer, etc., and selects the variable discharge amount pump 3 and the high-speed on/off valve 5 by comparing the target value and the actual value, and responds to the difference. It outputs an operation signal.

Since this second embodiment has the above configuration, the internal pressure control pattern in the pressure vessel is set as a target value in the arithmetic unit, and when control is started, the target value and actual value are compared every moment, and the When the variable discharge volume pump 3 or the high-speed on/off valve 5 operates, that is, when the actual feedback value is lower than the target internal pressure value, the variable discharge volume pump 3 operates at a rotational speed corresponding to the difference and pumps the liquid. Pressure actuator 1
If the feedback value as an actual value is higher than the internal pressure target value, the variable discharge amount pump 3
stops, and the high-speed on/off valve 5 opens and closes according to the difference, thereby controlling the internal pressure.

Even in this second embodiment, the same effects as in the first embodiment can be obtained by using the variable discharge amount pump 3 and the high-speed on/off valve 5.

〔Effect of the invention〕

As described above, the present invention uses a variable discharge pump to supply liquid, so it is possible to control pressurization according to the difference between the target value and the actual value, and the hydraulic unit is constantly driven to generate and maintain pressurized liquid. Unlike conventional structures that have to be left in place, there is less power loss, and the liquid is discharged through the opening and closing movements of the high-speed on/off valve, allowing for better pressure reduction control.Furthermore, the entire device can be simplified and manufacturing costs can be reduced. can.

As described above, the intended purpose can be fully achieved.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention; FIG. 1 is a control block diagram of the first embodiment, FIG. 2 is a flowchart thereof, FIG. 3 is a hydraulic circuit diagram thereof, and FIG.
The figure is a load control pattern diagram, Figure 5 is a control block diagram of the second embodiment, Figure 6 is a hydraulic circuit diagram,
FIG. 7 is a control block diagram of the conventional structure, FIG. 8 is a hydraulic circuit diagram thereof, and FIG. 9 is a diagram showing the relationship between load and displacement. DESCRIPTION OF SYMBOLS 1... Hydraulic pressure actuator, 3... Variable discharge amount pump, 4... Liquid supply pipe line, 5... High speed on/off valve, 6... Liquid return pipe line, 11... Arithmetic unit.

Claims (1)

[Claims] 1 The operating state of the hydraulic actuator is controlled by the amount of liquid supplied in the liquid supply pipe or the amount of liquid returned in the liquid return pipe, in which a variable discharge pump is disposed in the liquid supply pipe, and the above-mentioned A high-speed on-off valve is disposed in the return liquid conduit, and a calculation device is provided to select the variable discharge amount pump or the high-speed on-off valve by comparing the target value and the actual value, and to operate the same in response to the difference. A hydraulic actuator control device comprising: