CN101737380A - Electro-hydraulic load simulator with low-pressure oil pump - Google Patents

Abstract

An electro-hydraulic load simulation device with a low-pressure oil pump belongs to the technical field of electro-hydraulic servo control. The existing electro-hydraulic load simulator has its own frictional resistance torque, which on the one hand increases the burden on the tested motor, and on the other hand affects the torque simulation test results. The prior art also causes vibration of the hydraulic motor due to the negative pressure generated in the pipeline at the oil suction port of the hydraulic motor. The device of the present invention is equipped with a low-pressure oil pump on the oil suction pipeline of the hydraulic motor. Before and during the operation of the electro-hydraulic load simulation device, a back pressure is generated by the low-pressure oil pump to offset the static friction moment and avoid the generation of the negative pressure. It is used for simulation of servo system load.

Description

Electrohydraulic load simulator with low pressure oil pump

technical field

The invention relates to an electro-hydraulic load simulation device with a low-pressure oil pump, in which a low-pressure oil pump is used in a hydraulic power system to overcome the device's own friction resistance torque in a static and moving state, and belongs to the technical field of electro-hydraulic servo control.

Background technique

The electro-hydraulic load simulator is used to simulate various resistance torques that the motor bears during the motion of the servo system, such as inertial torque, wind resistance torque, unbalanced torque, etc. A Chinese invention patent application publication titled "Electro-hydraulic servo simulation device for follow-up system load" with application number 200910066801.7 discloses a typical scheme for simulating various loads by using electro-hydraulic servo loading, as shown in Fig. 1, the electro-hydraulic load simulation device is composed of hydraulic motor 1, reversing valve 2, servo valve 3, high-pressure oil pump 4, torque sensor 5, encoder 6, main control computer 7 and oil tank 8, torque sensor 5 and encoder 6 is installed on the torque output shaft of hydraulic motor 1, and is electrically connected with main control computer 7; main control computer 7 is electrically connected with the valve driver of servo valve 3; hydraulic motor 1, reversing valve 2, and servo valve 3 The connection between them is a conventional hydraulic oil circuit, and the hydraulic oil used is circulated in the oil tank 8. The torque sensor 5 is used to detect the torque provided by the simulation device, and the simulation of various loads is realized by controlling the opening of the servo valve 3 . The hydraulic motor 1 is connected to the tested motor 9 through a mechanical mechanism such as a coupling or a transmission, and the torque simulated by the electro-hydraulic load simulator is applied to the tested motor 9 .

The electro-hydraulic load simulation device itself has friction resistance torque, which mainly comes from the mechanical mechanism connecting the hydraulic motor 1 and the tested motor 9 and the hydraulic motor part. Especially when the tested motor 9 drives the electro-hydraulic load simulator from rest to motion, it is necessary to overcome the frictional resistance torque, that is, only when the tested motor 9 generates a driving torque equal to the frictional resistance torque, its rotating shaft starts to rotate. For the electro-hydraulic load simulator, if the frictional resistance torque existing in itself is not eliminated, it will inevitably cause errors in the torque output of the electro-hydraulic load simulator. The existing solution is to use software compensation, that is, determine the frictional resistance torque data through actual measurement, and use this data as the zero point. During the working process of the electro-hydraulic load simulation device, subtract this data from the detected torque data carried by the motor under test. Then proceed with subsequent processing. Although this method does not increase the components in the electro-hydraulic load simulation device, the torque carried by the tested motor 9 is increased, which increases the burden of the tested motor on the one hand, especially when the tested motor 9 has a small operating torque and When the friction resistance torque is large, it will be difficult for the tested motor 9 to drive the electro-hydraulic load simulation device; Torque simulation is carried out according to the design, which affects the test results.

Due to working conditions and noise, the hydraulic motor 1 in the electro-hydraulic load simulator is far away from the hydraulic power system with the high-pressure oil pump 4 as the core, and the self-priming capacity of the hydraulic motor 1 is limited. Negative pressure is generated in the pipeline. When the oil-air separation pressure is reached, the air in the oil will be separated. When the hydraulic oil with air enters the hydraulic motor 1, the hydraulic motor 1 will vibrate, so that it cannot work normally.

Contents of the invention

In order to solve the problem of the influence of friction resistance torque on the simulation results of the electro-hydraulic load simulator and the vibration of the electro-hydraulic load simulator during the simulation process due to air separation due to negative pressure in the hydraulic oil pipeline, we invented a low-pressure An electro-hydraulic load simulator for oil pumps.

Its components of the device of the present invention include a hydraulic motor 1, a reversing valve 2, a servo valve 3, a high-pressure oil pump 4, a torque sensor 5, an encoder 6, a main control computer 7 and an oil tank 8, and the torque sensor 5 and the encoder 6 are installed on The hydraulic motor 1 is on the torque output shaft, and is electrically connected to the main control computer 7, and the main control computer 7 is electrically connected to the valve driver of the servo valve 3. The hydraulic motor 1, the reversing valve 2, and the servo valve 3 are conventional The hydraulic oil circuit connection is characterized in that a low-pressure oil pump 11 is also installed on the oil suction pipe 10 of the hydraulic motor 1 .

The effect of the present invention is that the use of the low-pressure oil pump 11 to supply oil to the hydraulic motor 1 can solve the technical problems existing in the prior art. Before the electro-hydraulic load simulation device works, a back pressure generated by the low-pressure oil pump 11 is applied to the hydraulic motor 1 until the mechanical mechanism connecting the hydraulic motor 1 and the tested motor 9 makes the electro-hydraulic load simulation device at the critical point of operation. state, that is, the torque formed by the back pressure is equal to the static friction torque, and the tested motor 9 is equivalent to being in a state close to no load, or in other words, the starting load is very small. When the electro-hydraulic load simulation device starts to work, it is only necessary to determine the required analog torque to control the opening of the servo valve 3 according to the rotational speed of the motor 9 under test and the given command signal. The torque carried by the rotating shaft of the tested motor 9 is almost entirely the simulated torque applied by the electro-hydraulic load simulator. In addition, also due to the existence of the back pressure, the generation of negative pressure in the oil suction pipe 10 of the hydraulic motor 1 is avoided, and the air in the hydraulic oil will not be separated from it, and the vibration problem of the hydraulic motor 1 will follow. solve. The value detected by the torque sensor 5 is very close to the torque provided by the electro-hydraulic load simulator, and the detection result is more realistic. In addition, the existence of the back pressure is equivalent to pre-tightening the electro-hydraulic load simulator, which increases the stiffness of the electro-hydraulic load simulator and improves the simulation accuracy of the electro-hydraulic load simulator.

Description of drawings

Fig. 1 is a structural schematic diagram of an electro-hydraulic servo simulation device for a conventional servo system load. Fig. 2 is a structural schematic diagram of an electro-hydraulic load simulator with a low-pressure oil pump according to the present invention. Fig. 3 is a schematic diagram of the hydraulic oil flow direction of the hydraulic power system before the device of the present invention works, and this figure is also used as a summary drawing. Fig. 4 is a schematic diagram of the flow direction of hydraulic oil when the hydraulic motor in the hydraulic power system of the device of the present invention works in the pump state. Fig. 5 is a schematic diagram of the flow direction of hydraulic oil when the hydraulic motor in the hydraulic power system of the device of the present invention is working in the motor state.

Detailed ways

The components of the device of the present invention include a hydraulic motor 1, a reversing valve 2, a servo valve 3, a high-pressure oil pump 4, a torque sensor 5, an encoder 6, a main control computer 7 and an oil tank 8. The torque sensor 5 and the encoder 6 are installed on the torque output shaft of the hydraulic motor 1 and are electrically connected with the main control computer 7 respectively. The torque sensor 5 is a torque sensor that detects the torque borne by the motor 9 under test, and the obtained torque data is used as a feedback signal to control the output of the electro-hydraulic load simulator, so as to realize the closed-loop control of the electro-hydraulic load simulator. The encoder 6 is a shaft angle encoder, which rotates with the tested motor 9 to detect the moving speed of the tested motor 9 . The main control computer 7 is electrically connected with the valve driver of the servo valve 3 . The hydraulic motor 1, the reversing valve 2, and the servo valve 3 are connected by a conventional hydraulic oil circuit. The reversing valve 2 adopts a Y-type electro-hydraulic reversing valve with a median function. When the electro-hydraulic load simulation device is running without load, it is connected to the oil inlet and outlet of the hydraulic motor 1 to realize the connection between the oil outlet of the servo valve 3 and the hydraulic motor. 1 Conversion of oil inlet and oil outlet connections. The servo valve 3 controls its opening size according to the size and direction of the instruction signal from the main control computer 7, so as to realize the control of the working pressure of the oil inlet and the oil outlet of the hydraulic motor 1. The reversing valve 2 cooperates with the servo valve 3 to determine whether to control the working pressure of the oil inlet or the oil outlet of the hydraulic motor 1 . The working pressure is converted into torque through the hydraulic motor 1, and acts on the tested motor 9 through the torque output shaft. The high-pressure oil pump 4 is the main hydraulic pump, which adopts an oil pump motor unit with an integrated structure of a motor and a plunger hydraulic pump. Adjust the electromagnetic overflow valve 12 of the high-pressure oil pump to determine the output pressure of the high-pressure oil pump 4 . The hydraulic motor 1 is powered by a servo valve 3 . A low-pressure oil pump 11 is also installed on the oil suction pipe 10 of the hydraulic motor 1 . The low-pressure oil pump 11 is installed in the oil suction pipeline 10 close to the oil tank 8 section, avoiding forming negative pressure in the oil pipe from its oil inlet to the oil tank 8. The low-pressure oil pump 11 forms a back pressure in the oil suction pipeline 10 by supplying oil to the hydraulic motor 1 . The electromagnetic overflow valve 13 of the low-pressure oil pump is connected in parallel with the low-pressure oil pump 11. Under the control of the main control computer 7, the oil supply pressure of the low-pressure oil pump 11, that is, the back pressure, is adjusted to just enough to resist the frictional resistance moment and prevent A negative pressure sufficient to cause separation of air from the hydraulic oil is formed in the suction line 10 .

The present invention will be further illustrated below by describing the working process of the device of the present invention.

Before the electro-hydraulic load simulator works, the low-pressure oil pump 11 works and generates a back pressure, which directly generates a torque on the hydraulic motor 1. At this time, the reversing valve 2 is in a working position, and the servo valve 3 is not working. The flow direction of hydraulic oil is: oil tank 8, low-pressure oil pump 11, oil suction pipe 10, forward rotation check valve 14, hydraulic motor 1, reversing valve 2, two-way valve 15, oil tank 8, as shown in Figure 3. Adjust the electromagnetic overflow valve 13 of the low-pressure oil pump so that the back pressure reaches a state where the electro-hydraulic load simulation device is about to move but does not move.

After the electro-hydraulic load simulation device works, the tested motor 9 drives the hydraulic motor 1 to rotate, and the hydraulic motor 1 switches between pump and motor states according to the torque to be simulated by the electro-hydraulic load simulation device.

When the hydraulic motor 1 is working in the pump state, the tested motor 9 applies a torque to the hydraulic motor 1 to drive it to rotate, such as forward rotation. At this time, by controlling the opening of the servo valve 3, the resistance torque is established to act on the hydraulic motor 1 and transmitted to the tested motor 9 to realize resistance torque simulation. During this process, the low-pressure oil pump 11 continuously provides back pressure, and the torque generated by the back pressure on the hydraulic motor 1 is in the same direction as the torque applied to the hydraulic motor 1 by the tested motor 9 . When the hydraulic motor 1 is working in the pump state, the hydraulic oil flow direction is: oil tank 8, low-pressure oil pump 11, oil suction pipeline 10, forward rotation check valve 14, hydraulic motor 1, reversing valve 2, servo valve 3, oil return one-way Valve 16, oil groove 8, see as shown in Figure 4.

When the hydraulic motor 1 is working in the motor state, the motor 9 under test applies a torque to the hydraulic motor 1 to drive it to rotate, such as forward rotation. The high-pressure oil pump 4 provides power to the hydraulic motor 1 through the servo valve 3 to drive it to rotate, such as forward rotation. Then the hydraulic motor 1 converts the power into a torque in the same direction and applies it to the motor 9 under test. In this working state, by controlling the opening of the servo valve 3, a certain dynamic torque is established to act on the hydraulic motor 1 and transmitted to the tested motor 9 to realize the dynamic torque simulation. During this process, the low-pressure oil pump 11 still continuously provides back pressure, and the torque generated by the back pressure on the hydraulic motor 1 is in the same direction as the torque applied to the hydraulic motor 1 by the high-pressure oil pump 4 . When the hydraulic motor 1 works in the motor state, there are two hydraulic oil cycles in the electro-hydraulic load simulation device. The flow direction of the hydraulic oil driven by the low-pressure oil pump 11 is: oil tank 8, low-pressure oil pump 11, oil suction pipeline 10, forward rotation check valve 14, hydraulic motor 1, reversing valve 2, two-way valve 15, oil tank 8, see figure 5. The flow direction of the hydraulic oil driven by the high-pressure oil pump 4 is: oil tank 8, high-pressure oil pump 4, servo valve 3, reversing valve 2, hydraulic oil pump 1, reversing valve 2, two-way valve 14, and oil tank 8, as shown in Figure 5 Show.

After the electro-hydraulic load simulation device works, the tested motor 9 drives the hydraulic motor 1 to reverse, the flow path of the hydraulic oil in the hydraulic power system changes at the check valve link, and flows through the reverse check valve 17, and the other remains unchanged.

Claims (2)

1. electro-hydraulic load simulator with low pressure fuel pump, its constituent element comprises oil hydraulic motor (1), selector valve (2), servovalve (3), high pressure oil pump (4), torque transducer (5), encoder (6), main control computer (7) and oil groove (8), torque transducer (5) and encoder (6) are installed on oil hydraulic motor (1) the moment output shaft, and be electrically connected with main control computer (7) respectively, main control computer (7) is electrically connected with the valve actuator of servovalve (3), oil hydraulic motor (1), selector valve (2), be that conventional hydraulic circuit connects between servovalve (3) three, it is characterized in that, on the oil-absorbing pipeline (10) of oil hydraulic motor (1), low pressure fuel pump (11) is installed also.

2. electro-hydraulic load simulator according to claim 1 is characterized in that, low pressure fuel pump (11) be installed in oil-absorbing pipeline (10) near oil groove (8) section.

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