JPS62679A - Oil-pressure testing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hydraulic testing device such as an impulse tester.

(Prior Art) An impulse tester is known as a device that tests the durability of a member under test by intermittently applying hydraulic pressure at a predetermined frequency to the member under test.

This is usually constructed as shown in FIG.

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In some cases, an auxiliary pump 3 is provided.

The hydraulic control valve 4 controls the supply of pressure oil to the boost cylinder 5, and is composed of an electromagnetic hydraulic servo valve. The boost cylinder 5 is, for example, a pressure amplification cylinder that intermittently applies high pressure at a predetermined frequency to a rubber tube 6 as a member to be tested. Low pressure chambers 7 on the left and right sides of the boost cylinder 5
When pressure oil from the hydraulic control valve 4 is selectively sent to A and 7B, the piston 8 reciprocates from side to side, and the plunger 9 integrated with this moves the piston 8 and plunger 9 from the high pressure chamber 10.
A high pressure amplified according to the area ratio of is applied to the rubber tube 6.

The hydraulic control valve (servo valve) 4 operates in response to a signal from a control device (not shown), alternately guides pump discharge pressure to the left and right low pressure chambers 7A and 7B, and causes the boost cylinder 5 to reciprocate at a predetermined frequency. At this time, the discharged oil from one of the low pressure chambers 7A or 7B returns to the tank 10 through the hydraulic control valve 4. Therefore, the hydraulic pumps 2 and 3 are operated so as to compensate for this return amount. 8 (Problems to be Solved by the Invention) Therefore, the hydraulic pumps 2 and 3 need to supply pressure oil to compensate for this return, but this flow rate does not reach the member under test. It changes depending on the test mode of the applied hydraulic pulse.Therefore, the required supply amount differs depending on the test.

Therefore, in the past, in order to cover the required maximum flow rate, two
Two pumps 2 and 3 were installed, and when the maximum flow rate was not used, excess oil was released from the relief valve 12 to the tank 10 so that the inside of the circuit was maintained at a predetermined pressure.

However, when surplus oil is returned to the tank 10 through the I-no-7 valve 12 in this way, the two pumps 2.3 are always running at full speed, so pump drive energy is wasted unless necessary. , the energy loss becomes non-negligible as the oil temperature rises at 7. Therefore, under test conditions where the required flow rate is extremely low, consideration has been given to reducing energy loss by operating only one of the pumps 2.3, but in reality two pumps are often operated. This is because the experimental conditions vary widely and it is complicated to determine the number of vehicles in operation each time.
This is to provide more leeway by operating two vehicles.

The present invention aims to solve such problems.

(Means for Solving the Problems) The present invention provides a hydraulic test device in which a member to be tested is supplied with pressure oil from a hydraulic pump via a hydraulic control valve, in which the hydraulic pump is configured with a variable displacement pump, and the hydraulic Means for detecting the pressure in the circuit is provided, and means for controlling the discharge flow rate of the pump to increase or decrease so that the detected pressure becomes a predetermined value.

(Function) Therefore, when the required flow rate changes depending on the test mode of the impulse tester, the pressure in the circuit is detected and the discharge amount of the variable displacement pump is changed so as to reach a predetermined pressure. When the required flow rate is low, the pump driving torque is also reduced, thereby reducing energy consumption.

(Example) Embodiments of the present invention will be described below with reference to FIG.

In order to send pressure oil to the hydraulic circuit 1, a variable displacement pump 15 whose discharge amount increases and decreases is provided.

An accumulator 14 is connected to the hydraulic circuit 1 and stores a portion of pump discharge oil. The variable displacement pump 15 has a pump tilting angle adjusted by, for example, a servo motor 16,
The discharge flow rate changes.

The servo motor 16 is reversibly rotated by a signal from the control circuit 17 to increase or decrease the tilt angle.

The control circuit 17 includes a pressure switch 1 that detects circuit pressure.
A detection signal from 8 is input, and at the same time, a signal for detecting startup preparation and start of the hydraulic test is input from the startup circuit 19.

The control circuit 17 basically performs feedback control on the pump discharge amount so that the pressure in the hydraulic circuit 17 is maintained at a predetermined pressure specified by the pressure switch 18. However, at the start of the test, the discharge amount of the variable displacement pump 15 is 1. Hold it so that it is maximum, and open AA M l+ J! L button I4 〒Minamikusuyama
During the 5-10 hour period, the discharge amount is controlled to be gradually reduced as time passes.

In other words, at the start of the test, it is assumed that the pressure in the hydraulic circuit 1 will be insufficient due to leakage of hydraulic oil while the pump is stopped, so at this time, the discharge amount of the variable displacement pump 15 should be maintained at the maximum in advance. This allows the pressure to be restored immediately from the initial stage of the start and prevents a pressure shortage.In addition, from the above, pressure feedback control is not started immediately after the start when the required flow rate is relatively large, but is started from the maximum flow rate. By gradually reducing the flow rate, it is possible to reliably avoid instantaneous flow shortages due to hunting associated with feedback control.

Note that the pressure oil in the hydraulic circuit 1 is controlled by the "hydraulic control 9" as described above.
．． 4 to the boost cylinder 5, and applies a high hydraulic pulse of a predetermined frequency to the rubber tube 6 serving as the member to be tested.

Further, surplus oil in the hydraulic circuit 1 is returned to the tank 10 via the relief valve 12.

After h1 is completed as described above, the operation will be explained next with reference to the flowchart of FIG. 2 showing the control operation and the sequence chart of FIG. 3.

When a test start signal is input from the starting circuit 19 to the control circuit 17, an angle increase signal is first outputted to the servo motor 16 so that the tilting angle takes the maximum value during a preparation period prior to starting and moving. After the preparation period has elapsed, startup is performed, but at this point the discharge amount of the variable displacement pump 15 is set to the maximum value. After startup, oil discharged from the pump 15 is sent to the hydraulic circuit 1, and the circuit pressure rises above a predetermined value. Hydraulic control valve 4 controls low pressure chambers on the left and right sides of boost sill 5 at a predetermined frequency? When this pressure oil is alternately supplied to A and 7B, the amplified high pressure is supplied to the rubber tube 6, which is the member to be tested, in a pulse wave pattern, and the pressure resistance test is started.

After the start of the test, the control circuit 17 outputs an angle reduction signal to the servo motor 16 at predetermined time intervals so as to gradually reduce the tilt angle.

As a result, the tilt angle of the variable displacement pump 15 gradually decreases 9 toward the neutral position, and the discharge amount decreases accordingly. The circuit pressure gradually decreases as the pump discharge rate decreases, and when it eventually reaches the operating pressure of the pressure detection switch 18, this switch 18 is turned on. Then the control circuit 17
outputs a signal for increasing the tilt angle to the servo motor 16 for a predetermined short time so as to increase the pump discharge amount.

As a result, the pressure in the hydraulic circuit 1 rises slightly above the predetermined value to ensure the minimum flow rate required for the test.After that, the pressure is controlled so that the predetermined pressure specified by the pressure detection switch 18 is maintained. The circuit 17 provides feedback control of the circuit pressure.

Therefore, if there is a change in the required flow rate due to a change in the test mode, for example, if the required flow rate increases, it is necessary to increase the discharge amount of the variable displacement pump 15 in order to maintain the specified circuit pressure. The system detects the pressure drop in the circuit due to an increase in the required flow rate and performs the feedback control described above. As a result, the tilt angle is immediately corrected in the direction of increasing the pump discharge amount, thereby preventing the occurrence of insufficient flow rate. And it can definitely be prevented.

Note that in reality, the required flow rate is constant in the same test mode, so even though it is called feedback control, the tilt angle of the variable displacement pump 15 is often held constant, and the discharge amount may fluctuate. There are few.

The driving torque of the variable displacement pump 15 increases or decreases depending on the pump discharge amount, and therefore, the power consumption can be significantly reduced when the variable displacement pump 15 is controlled according to the required flow rate, compared to always maintaining the maximum flow rate.

(Effects of the Invention) As described above, according to the present invention, while detecting the pressure in the hydraulic circuit, the discharge flow rate of the variable displacement pump is controlled to increase or decrease so that a predetermined circuit pressure is maintained, and the test mode is changed. Even if the required flow rate fluctuates, the minimum flow rate required for the test is always ensured, so there is no wastage of drive energy for the variable displacement pump, and efficient operation is guaranteed.

[Brief explanation of drawings]

FIG. 1 is a hydraulic system showing an embodiment of the present invention, FIG. 2 is a 70-chart of control operations, and FIG. 3 is a sequence chart. Figure f:tS4 is a hydraulic circuit diagram of a conventional example. DESCRIPTION OF SYMBOLS 1... Hydraulic circuit, 4... Hydraulic control valve, 5... Boost sill, 6... Rubber tube, 15... Variable displacement pump, 16... Servo motor, 17... Control circuit , 18... Pressure detection switch, 19... Starting circuit. Patent applicant Yokohama Rubber Co., Ltd. Araba Kogyo Co., Ltd.

Claims (1)

[Claims] In a hydraulic testing device that supplies pressure oil from a hydraulic pump to a member under test via a hydraulic control valve, the hydraulic pump is configured with a variable displacement pump, and a means for detecting the pressure in the hydraulic circuit is provided. A hydraulic testing device characterized by comprising means for increasing or decreasing the discharge flow rate of the pump so that it reaches a predetermined value.