阅读说明：本技术 一种高频力加载电液系统 (High-frequency force loading electro-hydraulic system ) 是由 孔红梅 陈智星 于 2019-09-23 设计创作，主要内容包括：本发明提供一种高频力加载电液系统。所述高频力加载电液系统包括：液压油箱,用于容纳液压油；主阀组,与所述液压油箱连通,用于输送液压油；以及至少一个力加载单元,与所述主阀组连通,用于提供加载力；其中,所述力加载单元包括：高频响比例伺服阀,与所述主阀组连通；以及集成油缸,与所述高频响比例伺服阀连通,用于提供加载力；其中,在所述高频响比例伺服阀和所述集成油缸之间的油道中设置第一旁通泄油阻尼孔,使得所述集成油缸的回路形成C型液压半桥。根据本发明的实施例的高频力加载电液系统,通过采用所述高频响比例伺服阀,所述集成油缸可实现高频力加载功能,随输入信号曲线输出力曲线,尤其对小加载力控制更稳定。(The invention provides a high-frequency force loading electro-hydraulic system. The high-frequency force loading electro-hydraulic system comprises: the hydraulic oil tank is used for containing hydraulic oil; the main valve group is communicated with the hydraulic oil tank and used for conveying hydraulic oil; and at least one force loading unit in communication with the main valve block for providing a loading force; wherein the force loading unit comprises: the high-frequency response proportional servo valve is communicated with the main valve group; the integrated oil cylinder is communicated with the high-frequency response proportional servo valve and is used for providing loading force; and a first bypass oil discharge damping hole is arranged in an oil passage between the high-frequency response proportional servo valve and the integrated oil cylinder, so that a loop of the integrated oil cylinder forms a C-shaped hydraulic half bridge. According to the high-frequency force loading electro-hydraulic system provided by the embodiment of the invention, by adopting the high-frequency response proportional servo valve, the integrated oil cylinder can realize a high-frequency force loading function, and outputs a force curve along with an input signal curve, so that the control of small loading force is more stable.)

1. A high frequency force loading electro-hydraulic system, comprising:

the hydraulic oil tank is used for containing hydraulic oil;

the main valve group is communicated with the hydraulic oil tank and used for conveying hydraulic oil; and

at least one force loading unit in communication with the main valve block for providing a loading force;

wherein the force loading unit comprises:

the high-frequency response proportional servo valve is communicated with the main valve group; and

the integrated oil cylinder is communicated with the high-frequency response proportional servo valve and is used for providing loading force;

and a first bypass oil discharge damping hole is arranged in an oil passage between the high-frequency response proportional servo valve and the integrated oil cylinder, so that a loop of the integrated oil cylinder forms a C-shaped hydraulic half bridge.

2. The high-frequency force loading electro-hydraulic system according to claim 1, further comprising a pressure sensor and a controller, wherein the loading force provided by the integrated oil cylinder is fed back to the controller through the pressure sensor.

3. The high-frequency force loading electro-hydraulic system according to claim 1 or 2, wherein the main valve group has an oil inlet P, an oil return port T, a working oil port a and a working oil port B, the high-frequency response proportional servo valve has an oil inlet P, an oil return port T, a working oil port a and a working oil port B, and the first bypass oil discharge damping hole is disposed between the working oil port a of the high-frequency response proportional servo valve and the working oil port B of the main valve group.

4. The high-frequency force loading electro-hydraulic system according to claim 3, wherein a working oil port A of the high-frequency response proportional servo valve is communicated with a rodless cavity of the integrated oil cylinder, and a working oil port B of the high-frequency response proportional servo valve is communicated with a rod cavity of the integrated oil cylinder.

5. The high-frequency force loading electro-hydraulic system according to claim 4, wherein a positioning solenoid valve for maintaining the position of the integrated oil cylinder is arranged between a working oil port A of the high-frequency response proportional servo valve and a rodless cavity of the integrated oil cylinder.

6. The high-frequency force loading electro-hydraulic system according to claim 4, wherein a speed-limiting solenoid valve is arranged between the high-frequency response proportional servo valve and the working oil port B of the main valve group.

7. The high-frequency force loading electro-hydraulic system according to claim 6, wherein the speed-limiting solenoid valve has an oil inlet P, an oil return port T, a working oil port a and a working oil port B, the oil inlet P and the oil return port T of the speed-limiting solenoid valve are communicated with the working oil port B of the main valve group, the working oil port a of the speed-limiting solenoid valve is communicated with the first bypass oil-discharge damping hole, and the working oil port B of the speed-limiting solenoid valve is communicated with the oil return port T of the high-frequency response proportional servo valve.

8. The high-frequency force loading electro-hydraulic system according to claim 7, wherein a second bypass oil drainage damping hole is formed between an oil inlet P of the speed-limiting electromagnetic valve and a working oil port B of the main valve block.

9. The high-frequency force loading electro-hydraulic system as claimed in claim 8, wherein a third bypass oil drainage damping hole is formed between the rod cavity of the integrated oil cylinder and the working oil port B of the main valve block.

10. The high-frequency force loading electro-hydraulic system according to claim 1 or 2, characterized in that the high-frequency force loading electro-hydraulic system comprises a servo motor pump group, wherein the servo motor pump group comprises a hydraulic pump connected between a main valve group and the hydraulic oil tank and a servo motor for driving the hydraulic pump.

11. The high-frequency force loading electro-hydraulic system according to claim 10, wherein a first accumulator for compensating the flow of hydraulic oil is arranged in an oil passage in front of the high-frequency response proportional servo valve.

12. The high frequency force loading electro-hydraulic system of claim 11, wherein the main valve block is provided with a second accumulator for reducing pressure pulsations of the servo motor-pump block.

13. The high-frequency force loading electro-hydraulic system according to claim 1 or 2, characterized by comprising a plurality of force loading units, wherein the force loading units are arranged in parallel with each other.

Technical Field

The invention relates to a hydraulic control system, in particular to a high-frequency force loading electro-hydraulic system.

Background

The existing force loading servo hydraulic system is usually used in the working condition of larger output force. And when the output force is small, the force loaded on the sample piece is easy to overshoot, so that the output force of the control system is difficult to stabilize, and a preset force curve cannot be obtained finally.

Disclosure of Invention

In order to solve the technical problems in the prior art, the invention provides a high-frequency force loading electro-hydraulic system which can control an integrated oil cylinder to carry out high-frequency loading according to a preset force curve by using a high-frequency response proportional servo valve, can output the force curve along with an input signal curve, and is particularly more stable in control over small loading force.

According to one aspect of the invention, there is provided a high frequency force loading electro-hydraulic system comprising: the hydraulic oil tank is used for containing hydraulic oil; the main valve group is communicated with the hydraulic oil tank and used for conveying hydraulic oil; and at least one force loading unit in communication with the main valve block for providing a loading force; wherein the force loading unit comprises: the high-frequency response proportional servo valve is communicated with the main valve group; the integrated oil cylinder is communicated with the high-frequency response proportional servo valve and is used for providing loading force; and a first bypass oil discharge damping hole is arranged in an oil passage between the high-frequency response proportional servo valve and the integrated oil cylinder, so that a loop of the integrated oil cylinder forms a C-shaped hydraulic half bridge.

Optionally, the high-frequency force loading electro-hydraulic system further comprises a pressure sensor and a controller, and the loading force provided by the integrated oil cylinder is fed back to the controller through the pressure sensor.

Optionally, the main valve group has an oil inlet P, an oil return port T, a working oil port a, and a working oil port B, the high-frequency response proportional servo valve has an oil inlet P, an oil return port T, a working oil port a, and a working oil port B, and the first bypass oil-discharge damping hole is disposed between the working oil port a of the high-frequency response proportional servo valve and the working oil port B of the main valve group.

Optionally, a working oil port a of the high-frequency response proportional servo valve is connected with a rodless cavity of the integrated oil cylinder, and a working oil port B of the high-frequency response proportional servo valve is communicated with a rod cavity of the integrated oil cylinder.

Optionally, a positioning solenoid valve for maintaining the position of the integrated oil cylinder is arranged between the working oil port a of the high-frequency response proportional servo valve and the rodless cavity of the integrated oil cylinder.

Optionally, a speed-limiting solenoid valve is arranged between the high-frequency response proportional servo valve and the working oil port B of the main valve group.

Optionally, the speed-limiting solenoid valve has an oil inlet P, an oil return port T, a working oil port a, and a working oil port B, the oil inlet P and the oil return port T of the speed-limiting solenoid valve are communicated with the working oil port B of the main valve group, the working oil port a of the speed-limiting solenoid valve is communicated with the first bypass oil-draining damping hole, and the working oil port B of the speed-limiting solenoid valve is communicated with the oil return port T of the high-frequency response proportional servo valve.

Optionally, a second bypass oil drainage damping hole is arranged between the oil inlet P of the speed limiting electromagnetic valve and the working oil port B of the main valve group.

Optionally, a third bypass oil drainage damping hole is arranged between the rod cavity of the integrated oil cylinder and the working oil port B of the main valve group.

Optionally, the high-frequency force loading electro-hydraulic system comprises a servo motor pump set, and the servo motor pump set comprises a hydraulic pump connected between a main valve set and the hydraulic oil tank and a servo motor used for driving the hydraulic pump.

Optionally, a first accumulator for compensating the flow of the hydraulic oil is arranged in an oil passage in front of the high-frequency response proportional servo valve.

Optionally, the main valve block is provided with a second accumulator for reducing pressure pulsations of the servo motor pump block.

Optionally, the high-frequency force loading electro-hydraulic system comprises a plurality of force loading units, and the force loading units are arranged in parallel with each other.

Compared with the prior art, the technical scheme of the embodiment of the invention has the following beneficial effects:

by adopting the high-frequency response proportional servo valve, the hydraulic integrated oil cylinder can realize the high-frequency force loading function, output a force curve along with an input signal curve and particularly control small loading force more stably. And the pressure of the integrated oil cylinder is controlled by adopting a C-shaped hydraulic half-bridge in a hydraulic principle, so that the overshoot of the pressure control of the force loading electro-hydraulic system is reduced, and the stability of the closed-loop control system is greatly improved.

Furthermore, a positioning electromagnetic valve for keeping the position of the integrated oil cylinder is arranged between a working oil port A of the high-frequency response proportional servo valve and a rodless cavity of the integrated oil cylinder, so that the high-frequency force loading electro-hydraulic system can be safely used in the vertical direction, and has the functions of pressure maintaining positioning and load bearing stable descending.

Furthermore, a speed-limiting electromagnetic valve is arranged between the high-frequency response proportional servo valve and the working oil port B of the main valve group, so that the speed of hydraulic oil in the oil return pipeline can be effectively controlled, and stable force loading is provided.

Furthermore, a servo motor pump set is adopted to perform pressure closed-loop control to provide a constant voltage source, and the energy-saving and noise-reducing effects are achieved.

Drawings

Other features and advantages of the present invention will be better understood by the following detailed description of alternative embodiments, taken in conjunction with the accompanying drawings, in which like characters represent the same or similar parts, and in which:

FIG. 1 is a schematic diagram of a portion of a high frequency force loading electro-hydraulic system, showing primarily a force loading unit of the high frequency force loading electro-hydraulic system, according to one embodiment of the present invention;

FIG. 2 is a schematic structural diagram of another part of a high-frequency force loading electro-hydraulic system, mainly illustrating a hydraulic oil tank and a main valve block of the high-frequency force loading electro-hydraulic system, according to one embodiment of the invention; and

FIG. 3 illustrates a hydraulic schematic of a high frequency force loading electro-hydraulic system according to one embodiment of the present invention.

Detailed Description

The practice and use of the embodiments are discussed in detail below. It should be understood, however, that the specific embodiments discussed are merely illustrative of specific ways to make and use the invention, and do not limit the scope of the invention. The description herein of the structural positions of the respective components, such as the directions of upper, lower, top, bottom, etc., is not absolute, but relative. When the respective components are arranged as shown in the drawings, these direction expressions are appropriate, but when the positions of the respective components in the drawings are changed, these direction expressions are changed accordingly.

With the development of the national science and technology, research and test of various disciplines are the key of scientific and technological development, and particularly, a test bed for scientific research and test is more and more important. For example, at present, only three knee joint prosthesis friction testing machines exist in China, five hip joint prosthesis friction testing machines exist in China, and all the hip joint prosthesis friction testing machines come from imports. Because the prior art is limited by foreign countries, the problems of high purchase price, overhigh maintenance cost and the like are faced, so that domestic researchers are perplexing.

Based on the current situation, the invention designs a high-frequency force loading electro-hydraulic system based on the force loading requirement on the prosthesis friction testing machine, controls the integrated oil cylinder to carry out high-frequency loading according to a preset force curve by using a high-frequency response proportional servo valve, and feeds the loading force back to a system controller in real time through a pressure sensor to carry out PID operation, thereby forming closed-loop control.

FIG. 1 illustrates a force loading single cell of a high frequency force loading electro-hydraulic system according to one embodiment of the present invention; FIG. 2 illustrates a hydraulic tank and a main valve block of a high frequency force loading electro-hydraulic system according to one embodiment of the present invention; FIG. 3 illustrates a hydraulic schematic of a high frequency force loading electro-hydraulic system according to one embodiment of the present invention. Generally, the high-frequency force loading electro-hydraulic system comprises a power station and a force loading unit, wherein the core of the power station is a motor-pump set or the root of the power station is the motor-pump set.

Specifically, the high frequency force loading electro-hydraulic system 100 basically includes a hydraulic tank 10, a main valve block 20 and at least one force loading unit 30. The hydraulic oil tank 10 is used for containing hydraulic oil, and the main valve assembly 20 is communicated with the hydraulic oil tank 10 and used for conveying the hydraulic oil to the force loading unit 30. The force loading unit 30 is in communication with the main valve block 20 for providing a loading force.

The main valve block 20 may take the form of a hydraulic manifold. The hydraulic manifold block can be a valve block body pre-drilled with a plurality of holes, various hydraulic elements such as a hydraulic valve, a pipe joint, a pressure gauge and the like are installed on the hydraulic manifold block, and pore channels inside the hydraulic manifold block are communicated with pore channels of the elements to form a hydraulic manifold circuit so as to meet the control requirement of a hydraulic system.

The high-frequency force application electrohydraulic system 100 may include a plurality of force application units 30, the plurality of force application units 30 being arranged in parallel with one another, for example, two force application units 30 are shown in the exemplary embodiment in fig. 3.

Each force loading unit 30 includes a high-frequency response proportional servo valve 31 and an integrated cylinder 32. The high-frequency response proportional servo valve 31 is communicated with the main valve group 20, and the integrated oil cylinder 32 is communicated with the high-frequency response proportional servo valve 31 and used for providing loading force. Wherein, a first bypass oil discharge damping hole 33 is arranged in an oil passage between the high frequency response proportional servo valve 31 and the integrated oil cylinder 32, so that a loop of the integrated oil cylinder forms a C-shaped hydraulic half bridge.

According to some embodiments of the present invention, the high frequency force loading electro-hydraulic system 100 further comprises a pressure sensor and a controller, and the loading force provided by the integrated oil cylinder 32 is fed back to the controller through the pressure sensor.

According to some embodiments of the present invention, the main valve block 20 has an oil inlet P, an oil return port T, a working oil port a, and a working oil port B, the high frequency response proportional servo valve 31 has an oil inlet P, an oil return port T, a working oil port a, and a working oil port B, and the first bypass oil drain damping hole 33 is disposed between the high frequency response proportional servo valve 31 and the hydraulic oil tank 10. More specifically, the first bypass oil drain orifice 33 is disposed between the working port a of the high frequency response proportional servo valve 31 and the working port B of the main valve block 20.

The high-frequency response proportional servo valve 31 has four stations, namely a first station, a second station, a third station and a fourth station from left to right in fig. 3, and when the high-frequency response proportional servo valve 31 is located at the first station, four oil ports of the high-frequency response proportional servo valve 31 are not communicated; when the high-frequency response proportional servo valve 31 is positioned at the second station, the oil inlet P of the high-frequency response proportional servo valve 31 is communicated with the working oil port B, and the oil return port T is communicated with the working oil port A; when the high-frequency response proportional servo valve 31 is positioned at the fourth station, the oil inlet P of the high-frequency response proportional servo valve 31 is communicated with the working oil port A, and the oil return port T is communicated with the working oil port B; the third station has a neutral function, and when an electric signal enters, the electric signal can be continuously and variably switched to the second station to the fourth station along with the change of the current.

According to some embodiments of the present invention, the working oil port a of the high frequency response proportional servo valve 31 is communicated with the rodless cavity of the integrated oil cylinder 32, and the working oil port B of the high frequency response proportional servo valve 31 is communicated with the rod cavity of the integrated oil cylinder 32.

According to some embodiments of the present invention, the force loading unit 30 is further provided with a positioning solenoid valve 34 for maintaining the position of the integration cylinder 32, and the positioning solenoid valve 34 is disposed between the high-frequency-response-ratio servo valve 31 and the integration cylinder 32, more specifically, between the working oil port a of the high-frequency-response-ratio servo valve 31 and the rodless cavity of the integration cylinder 32.

According to some embodiments of the present invention, the force loading unit 30 is further provided with a speed-limiting solenoid valve 35 for controlling the speed of hydraulic oil, and the speed-limiting solenoid valve 35 is disposed between the high-frequency response proportional servo valve 31 and the hydraulic oil tank 10, and more specifically, between an oil return port T of the high-frequency response proportional servo valve 31 and a working oil port B of the main valve group 20.

In the embodiment shown in fig. 1, the first bypass oil-discharge orifice 33, the positioning solenoid valve 34 and the speed-limiting solenoid valve 35 are integrated into a functional valve block 40, which not only makes the space more compact, but also realizes a modular design.

According to some embodiments of the present invention, the speed-limiting solenoid valve 35 has an oil inlet P, an oil return port T, a working oil port a, and a working oil port B, the oil inlet P and the oil return port T of the speed-limiting solenoid valve 35 are communicated with the working oil port B of the main valve group 20, the working oil port a of the speed-limiting solenoid valve 35 is communicated with the first bypass oil-discharge damping hole 33, and the working oil port B of the speed-limiting solenoid valve 35 is communicated with the oil return port T of the high frequency response proportional servo valve 31.

According to some embodiments of the present invention, a second bypass oil drain damping hole 36 is disposed between the oil inlet P of the speed-limiting solenoid valve 35 and the working oil port B of the main valve block 20. The second bypass oil drainage damping hole 36 is arranged, so that the speed-limiting electromagnetic valve 35 can effectively control the speed of hydraulic oil in the oil return pipeline, and the speed is more stable when the loading oil cylinder retracts.

According to some embodiments of the present invention, a third bypass drain damping orifice 37 is provided between the rod chamber of the integrated cylinder 32 and the working port B of the main valve block 20.

According to some embodiments of the invention, a first accumulator 38 for compensating the hydraulic oil flow is provided in the oil passage in front of the high frequency response proportional servo valve 31.

According to some embodiments of the present invention, the high frequency force loading electro-hydraulic system 100 comprises a servo motor-pump set 11, wherein the servo motor-pump set 11 comprises a hydraulic pump 111 connected between a main valve set 20 and the hydraulic oil tank 10 and a servo motor 112 for driving the hydraulic pump 111.

As shown in fig. 3, the hydraulic oil tank 10 is connected to the hydraulic pump 111, and then connected to the main valve block 20 through the check valve 12, specifically to the oil inlet P of the main valve block 20. When the servo motor 112 is started, the hydraulic pump 111 is driven to convey the hydraulic oil in the hydraulic oil tank 10 to the main valve block 20 through the check valve 12, and the check valve 12 can prevent the hydraulic oil from flowing backwards. An air cooling machine 13, a one-way valve 14 and an oil return filter 15 are sequentially connected between an oil return port T of the main valve group 20 and the hydraulic oil tank 10, the air cooling machine 13 is used for cooling hydraulic oil of an oil return pipeline, and the oil return filter 15 is used for filtering impurities in return oil of the system.

The hydraulic oil tank 10 is also provided with an air cleaner 16 and a temperature sensor 17. The air filter 16 is used for communicating the atmosphere with the hydraulic oil tank and filtering impurities in the air, and the temperature sensor 17 can convert the temperature of the hydraulic oil into an electric signal so as to control whether the air cooling machine 13 is started and prevent the temperature of the hydraulic oil in the force loading electro-hydraulic system from being overheated.

The main valve group 20 comprises a pressure sensor 21, a pressure gauge 22, a high-pressure filter 23, an overflow valve 24, an unloading valve 25 and a second accumulator 26. The pressure sensor 21 is connected to the check valve 12, and can convert the pressure signal into an electrical signal to be fed back to a controller (not shown). The pressure gauge 22 is connected with the pressure sensor 21 and used for displaying the pressure of hydraulic oil, so that debugging and maintenance personnel can observe whether the pressure of the equipment is normal or not. The high-pressure filter 23 is connected with the pressure gauge 22 and used for filtering out impurities in hydraulic oil, and the overflow valve 24 is connected between the pressure sensor 21 and the oil return port T of the main valve assembly 20 and mainly plays roles in limiting system pressure and safety protection through overflow. The unloading valve 25 is connected between the working oil port a and the oil return port T of the main valve block 20, an initial default working position of the unloading valve 25 is normally open, and when the servo motor 112 and the hydraulic pump 111 are started, no-load starting can be realized; when the unloading valve 25 is electrified in normal operation, the loading of an electro-hydraulic system can be realized, and the system is in a ready state. A second accumulator 26 is connected between the high pressure filter 23 and the working port a of the main valve block 20 for buffering pressure pulsation of the hydraulic pump 111. To this end, the hydraulic pump 111 sucks and discharges hydraulic oil from the hydraulic oil tank 10, and supplies the hydraulic oil to the integration cylinders 32 of the external one or more force application units 30 through the main valve block 20.

When hydraulic oil enters the force loading unit 30 from the main valve group 20, the hydraulic oil firstly enters the first accumulator 38, and the first accumulator 38 can provide the hydraulic oil for the high-frequency response proportional servo valve 31, so that the response speed of the whole force loading electro-hydraulic system is improved. When the high frequency response proportional servo valve 31 is not powered, the high frequency response proportional servo valve is in the first station (O-type), and at this time, the four working oil ports of the high frequency response proportional servo valve 31 are not communicated, so that when an electric signal enters, the high frequency response proportional servo valve can be continuously switched to the second station to the fourth station along with the change of the current. When force loading is needed, the positioning electromagnetic valve 34 is electrified, so that an oil path leading to the integration oil cylinder 32 is communicated, and when the force loading is not needed, the positioning electromagnetic valve 34 is electrified, so that the oil path leading to the integration oil cylinder 32 is disconnected, and then the positioning electromagnetic valve 34 can enable the integration oil cylinder 32 to reliably keep the original position and not slide down along with the action of gravity. When the high-frequency response proportional servo valve 31 is located at the fourth station, the oil inlet P is communicated with the working oil port a, hydraulic oil enters the rodless cavity of the integrated oil cylinder 32 on one side, and flows back to the hydraulic oil tank 10 through the first bypass oil leakage damping hole 33 and the speed limiting electromagnetic valve 35 on the other side. At this moment, high frequency response proportional servo valve 31 and first bypass oil discharge damping hole 33 have formed C type hydraulic pressure half-bridge, and pressure chamber oil inlet end (proportional servo valve) damping is variable promptly, and the damping of oil outlet end (first bypass oil discharge damping hole) is fixed damping, and the design can prevent to a great extent that power loading electricity liquid system pressure overshoot is too big so that the stability of power loading electricity liquid system has been improved by a wide margin. At this time, the return oil of the high frequency response proportional servo valve 31 and the first bypass oil leakage damping hole 33 can flow back to the hydraulic oil tank 10 through the speed limiting solenoid valve 35 and the main valve group 20.

When the integrated oil cylinder 32 needs to descend, the high-frequency response proportional servo valve 31 is switched to a second station, so that the oil inlet P of the high-frequency response proportional servo valve 31 is connected with the working oil port B. At this time, because the area difference between the rod cavity and the rodless cavity of the integrated oil cylinder 32 is too large, in order to prevent the falling speed of the integrated oil cylinder 32 from being too fast, when the hydraulic oil enters the rod cavity of the integrated oil cylinder 32, the hydraulic oil can flow back to the hydraulic oil tank 10 through the third bypass oil drainage damping hole 37, and the bypass throttling effect is achieved. Meanwhile, the speed-limiting electromagnetic valve 35 is powered on and is positioned at a station on the right side in the figure, at this time, an oil return path of an oil return port T of the high-frequency response proportional servo valve 31 is cut off, oil return in the rodless cavity of the integrated oil cylinder 21 must enter the speed-limiting electromagnetic valve 35 through the first bypass oil drainage damping hole 33 and then flow back to the hydraulic oil tank 10 through the second bypass oil drainage damping hole 36, and the second bypass oil drainage damping hole 36 plays a role in controlling the oil return speed of the rodless cavity of the integrated oil cylinder 21. In the above-described embodiment, the circuit formed by the high frequency response proportional servo valve 31, the first bypass oil drain orifice 33 and the integration cylinder 32 constitutes the circuit of the C-type hydraulic half bridge.

When the force loading electro-hydraulic system stops or is powered off, although the high-frequency response proportional servo valve 31 is closed, the integrated oil cylinder 32 cannot be safely kept at the original position due to the existence of the first bypass oil leakage damping hole 33, and therefore a positioning electromagnetic valve is arranged between the high-frequency response proportional servo valve and the integrated oil cylinder, the positioning electromagnetic valve is provided with a leakage-free cone valve core, the integrated oil cylinder can be kept at the original position and cannot slide down, and the purpose of safely and reliably keeping the position is achieved.

When the integrated oil cylinder 32 descends, because the area of the integrated oil cylinder 32 is large, that is, the area of the rod cavity is small, a very small flow can obtain a very large speed at this time, and the load gravity is the same as the descending direction of the integrated oil cylinder 32, if the high-frequency-response-ratio servo valve is opened, the oil port of the high-frequency-response-ratio servo valve and the first bypass oil discharge damping hole can prevent the load cavity from forming back pressure, so that the integrated oil cylinder descends and stalls. Therefore, a speed limiting electromagnetic valve is arranged between the high-frequency response proportional servo valve and the hydraulic oil tank, and the function of the speed limiting electromagnetic valve is that the oil return of the high-frequency response proportional servo valve under the normal condition has no influence on the oil return of the first bypass oil discharge damping hole. And when the integrated oil cylinder performs a descending action, the oil return of the high-frequency response proportional servo valve is closed, the oil return passing through the first bypass oil drainage damping hole passes through the second bypass oil drainage damping hole again to form oil return throttling and speed regulation, and the stable descending back pressure of the integrated oil cylinder is ensured. And the rod cavity of the integrated oil cylinder is also connected with the third bypass oil drainage damping hole in parallel, so as to form bypass throttling speed regulation. The second bypass oil drainage damping hole and the third bypass oil drainage damping hole are matched with each other, so that the integrated oil cylinder can descend stably.

In addition, in the aspect of a power source, a servo motor pump set is adopted, and a pressure sensor transmits the output pressure of the hydraulic pump to a servo driver in a feedback mode to form closed-loop control. The high-frequency response proportional servo valve is provided with a first energy accumulator used for compensating the flow of hydraulic oil in front, so that the flow can be quickly compensated, and the pressure fluctuation before the valve caused by the change of the valve opening is reduced. In addition, the main valve group is provided with a second accumulator which can reduce the pressure pulsation output by the pump to the minimum.

In the embodiment of the invention, the high-frequency response proportional servo valve, the electromagnetic valve, the energy accumulator and the integrated oil cylinder are highly integrated, so that the space is more compact, the modular design is realized, the oil volume of a loaded load cavity is reduced, the natural frequency of the integrated oil cylinder is increased, and the influence of the elastic modulus of the oil on the dynamic characteristic of the force loading electro-hydraulic system is reduced.

While the technical content and the technical features of the invention have been disclosed, it is understood that various changes and modifications of the disclosed concept can be made by those skilled in the art within the spirit of the invention, and the invention is not limited thereto. The above description of embodiments is intended to be illustrative, and not restrictive, and the scope of the invention is defined by the appended claims.