Compensation type hydraulic actuator static test method and device

Abstract

The invention discloses a compensation type hydraulic actuator static test method and device. According to the device, the liquid leakage condition of the sealing ring in the static test of the actuator is considered, and a more accurate measurement result is obtained through compensation control of the servo control system. The test device comprises a hydraulic actuator static test structure part and a servo control part. The static test structure part comprises a special clamp matched with an actuator lug ring, and the special clamp is used for achieving fastening connection between an actuator and a testing machine. The servo control part comprises a sensor, a signal generator, a control test box and the like, the piston sealing ring is made of a conductive rubber composite material, and a high-sensitivity strain sensor is formed and used for feeding back deformation data of the sealing ring. Compensation control is carried out on displacement of the piston of the actuator through the servo control system, and stability of the position of the piston in the test process is effectively guaranteed. Compared with traditional servo control only based on piston displacement feedback, the method is more accurate and rapid, and the reliability of the static test result of the actuator can be guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of static testing, and in particular to a static testing method and device for a compensating hydraulic actuator. Background Art

[0002] In the development process of hydraulic actuators, mechanical properties such as static strength, vibration resistance, and impact resistance are very important indicators, and the level of these indicators directly determines the performance of the product. Therefore, in the development and design stage of the actuator, it is necessary to conduct corresponding tests according to the external loads that the actuator may be subjected to during operation, such as static tests, pressure tests, random vibration tests, impact tests, etc. Among them, static tests and pressure tests are static tests, which are mainly used to check whether the structural strength of the actuator meets the load requirements. As a prerequisite for dynamic tests, this test is very important for the design and development of actuators.

[0003] However, there are few static test systems and test methods for hydraulic actuators. Existing static test equipment needs to be designed separately for the structure and working characteristics of the hydraulic actuator, with a long development cycle and high cost. The universal testing machine is a material testing machine that integrates functions such as stretching and compression. A special fixture designed for it can be used to stretch and compress the actuator through the universal testing machine. It is easy to install and disassemble, and can be adapted to various types of hydraulic actuators for static testing. In addition, the current static tests on actuators all use a closed-loop control system based on piston displacement feedback. However, this control method does not take into account the leakage of oil in the actuator cylinder cavity, and its control accuracy is not high and the speed is slow. Therefore, it is of great significance to design a test device that is easy to install and has strong applicability, as well as a test method with high control accuracy and rapid response for the static test of hydraulic actuators.

[0004] During the static test of the actuator, the oil pressure difference between the two chambers in the actuator cylinder will cause the oil to leak through the seal ring, which will cause the piston position to shift. At present, the application of conductive rubber composite materials in the field of intelligent sensing has achieved initial results. The piston seal ring made of this material can not only meet the sealing function, but also feedback the deformation of the seal ring and compensate the oil pressure through the servo control system, so as to keep the piston position stable and the test results reliable. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a static test method and device for a compensating hydraulic actuator.

[0006] In order to achieve the above object, the present invention adopts the following technical solution: A static test device for a compensating hydraulic actuator comprises an earring fixture at an extended end of the hydraulic actuator, an earring fixture at a fixed end, and a servo control part; One end of the protruding end earring fixture is used to connect with the protruding end earring of the hydraulic actuator, and the other end is used to connect with the universal testing machine. One end of the fixed end earring fixture is used to connect with the fixed end earring of the hydraulic actuator, and the other end is used to connect with the universal testing machine. The servo control part includes a sensor, a signal generator, a control test box and a servo valve. The sensor includes a strain sensor formed by a piston sealing ring and a displacement sensor inside the piston. After the control test box receives the voltage signal given by the signal generator, it outputs a control signal to the servo valve. The servo valve controls the actuator piston to move to the position corresponding to the signal value by adjusting the oil pressure and flow rate in the hydraulic actuator cavity.

[0007] A further improvement of the present invention is that the earring fixture at the extended end adopts a claw-type structure and is provided with bolt holes for connecting with the earring at the extended end of the hydraulic actuator.

[0008] A further improvement of the present invention is that a thread and a pin hole are provided at the other end of the protruding end earring clamp, and the pin passes through the pin hole to connect the protruding end earring clamp to the universal testing machine. The clamp cooperates with the thread and applies a pre-tightening force to ensure that the clamp is firmly connected to the universal testing machine.

[0009] A further improvement of the present invention is that a bolt hole is arranged at one end of the fixed end earring clamp and is connected to the fixed end earring of the hydraulic actuator through a bolt, and the other end of the bolt cooperates with a nut.

[0010] A further improvement of the present invention is that a thread and a pin hole are provided at the other end of the fixed end earring clamp, the pin passes through the pin hole to connect the protruding end earring clamp with the universal testing machine, the clamp cooperates with the thread, and a pre-tightening force is applied to ensure that the clamp is firmly connected to the universal testing machine.

[0011] A further improvement of the present invention is that the fixed end of the hydraulic actuator is a double-ear structure, the extended end is a single-ear structure, and the maximum load is 10 tons.

[0012] A further improvement of the present invention is that the sealing ring at the groove of the hydraulic actuator piston is made of a conductive rubber composite material.

[0013] A further improvement of the present invention is that a pair of sensor contacts are symmetrically arranged at the bottom of the groove of the hydraulic actuator piston; channels are symmetrically arranged inside the actuator piston; a connecting wire is provided inside the actuator piston, and one end of the connecting wire is connected to the metal contact, and the other end passes through the channel inside the piston and is connected to the internal circuit of the displacement sensor through the gap between the sensor sleeve and the inner wall of the piston.

[0014] A further improvement of the present invention is that the resistance change signal of the piston sealing ring is transmitted to the servo control box through the plug. The servo control box determines the deformation of the sealing ring based on the piezoresistive effect and applies a feedback signal to the servo valve. The servo valve adjusts the oil pressure and flow rate in the actuator chamber according to the signal to compensate for leakage at the sealing ring.

[0015] A static test method for a compensated hydraulic actuator, based on the static test device for a compensated hydraulic actuator, comprises: During the test, the hydraulic actuator is connected to the universal testing machine through the earring fixture at the extended end and the earring fixture at the fixed end. After the control test box receives the voltage signal given by the signal generator, it outputs a control signal to the servo valve. The servo valve controls the actuator piston to move to the position corresponding to the signal value by adjusting the oil pressure and flow rate in the hydraulic actuator cavity. Then the universal testing machine applies a load to the hydraulic actuator through the fixture. During this process, the displacement sensor transmits the displacement signal of the piston in the cylinder to the control test box through the plug. During the control process, the oil pressure difference between the two chambers inside the hydraulic actuator will cause the piston seal in the piston groove to deform and leak, which will cause the oil pressure in the cavity to be unstable and the piston position to shift. The piston seal can form a strain sensor and transmit the piston seal deformation signal to the control test box through the contact and the plug. The control test box receives the displacement signal of the piston and the seal deformation signal feedback to form a closed-loop control, further adjust the oil pressure and flow, and ensure the stability of the piston position during the static test.

[0016] Compared with the prior art, the present invention has at least the following beneficial technical effects: 1. In the present invention, when the device is used, the hydraulic actuator fixed end and output end clamps can ensure that the hydraulic actuator is firmly connected to the universal testing machine chuck during static testing, and the actuator ear ball shaft is kept stable during the load application process.

[0017] 2. A method for arranging a piston sealing ring strain sensor is provided. In the present invention, a passage is formed by metal contacts at the bottom of the piston groove, wires at the internal channel of the piston, and a piston sealing ring made of a conductive rubber composite material, and a resistance change signal of the piston sealing ring can be transmitted to a control test box through a plug.

[0018] 3. A pressure relief compensation method is provided. In the present invention, when the device is used, based on the piezoresistive effect, the servo control box can determine the deformation of the sealing ring according to the change in the resistance of the piston sealing ring, and then obtain the degree of oil leakage in the working chamber of the cylinder. The closed-loop control circuit formed by the servo control box and the piston sealing ring strain sensor is used to compensate for the displacement control of the piston, thereby maintaining the stability of the oil pressure and further ensuring the stability of the piston position. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 It is a schematic diagram of the structure of the earring fixture at the extended end; Figure 2 It is a schematic diagram of the structure of the fixed-end earring fixture; Figure 3 It is a schematic diagram of the assembly structure of the fixture and the actuator; Figure 4 It is a schematic diagram of the actuator profile sensor arrangement; Figure 5 It is a schematic diagram of the assembly of the actuator and the testing machine; Figure 6 This is a system organization chart.

[0021] Description of reference numerals: 1. Bolt hole position; 2. Thread; 3. Pin hole position; 4. Claw structure; 5. Pin; 6. Clamp; 7. Bolt; 8. Nut; 9. Plug; 10. Earring fixture at the extended end; 11. Earring fixture at the fixed end; 12. Hydraulic actuator; 13. Metal contact; 14. Piston sealing ring; 15. Sensor channel; 16. Displacement sensor sleeve; 17. Connecting wire; 18. Displacement sensor; 19. Universal testing machine; 20. Fixed end chuck of universal testing machine. DETAILED DESCRIPTION

[0022] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0023] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0024] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0025] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0027] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0028] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0029] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0030] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0031] Example 1 like Figures 1 to 5 As shown, a compensating hydraulic actuator static test device provided by the present invention comprises an earring fixture 10 of the hydraulic actuator extension end, an earring fixture 11 of the fixed end and a servo control part; one end of the earring fixture 10 of the extension end is used to connect with the earring of the hydraulic actuator 12, and the other end is used to connect with the universal testing machine 19; one end of the earring fixture 11 of the fixed end is used to connect with the earring of the fixed end of the hydraulic actuator 12, and the other end is used to connect with the universal testing machine; the servo control part comprises a sensor, a signal generator, a control test box and a servo valve, the sensor comprises a strain sensor formed by a piston sealing ring 14 and a displacement sensor 18 inside the piston, after the control test box receives the voltage signal given by the signal generator, it outputs a control signal to the servo valve, and the servo valve controls the actuator piston to move to the position corresponding to the signal value by adjusting the oil pressure and flow rate in the cavity of the hydraulic actuator 12.

[0032] The present invention specifically includes a special fixture and a servo control part designed for a universal testing machine and a hydraulic actuator. Figures 1 to 3 As shown, the specially designed fixture includes an earring fixture 10 at the protruding end and an earring fixture 11 at the fixed end of the hydraulic actuator, and the hydraulic actuator 12 is connected to the universal testing machine 19 through the earring fixture 10 at the protruding end and the earring fixture at the fixed end; Figures 3 to 5 As shown, the servo control part includes a sensor, a signal generator, a control test box and a servo valve.

[0033] In this embodiment, the protruding end earring fixture 10 adopts a claw-shaped structure 4 based on the three-point positioning principle, and is provided with a bolt hole 1 to be connected to the protruding end earring of the hydraulic actuator 12 through a bolt 7 and a nut 8.

[0034] In this embodiment, the other end of the protruding end earring clamp 10 is provided with a thread 2 and a pin hole 3. The pin 5 passes through the pin hole 3 to connect the protruding end earring clamp 10 to the universal testing machine 19. The clamp 6 cooperates with the thread 2 to apply a pre-tightening force to ensure that the clamp 10 is firmly connected to the universal testing machine 19.

[0035] In this embodiment, a bolt hole 1 is provided at the upper end of the fixed end earring fixture 11 and connected to the fixed end earring of the hydraulic actuator 12 via a bolt 7, and the other end of the bolt 7 cooperates with a nut 8 to ensure a stable connection during the test.

[0036] In this embodiment, the other end of the fixed end earring fixture 11 is provided with a thread 2 and a pin hole 3, and the connection method between the fixed end earring fixture 11 and the universal testing machine 19 is the same as that of the extended end earring.

[0037] In this embodiment, the fixed end of the hydraulic actuator is a double-ear structure, the extended end is a single-ear structure, and the maximum load is 10 tons.

[0038] In this embodiment, the sensor of the servo control part includes a strain sensor formed by a piston seal ring 14 and a displacement sensor 18 inside the piston. The signal generator gives a DC voltage signal to the control test box, and the control test box receives the signal and transmits the control signal to the servo valve. The servo valve controls the displacement of the piston by changing the oil pressure and flow until the piston remains at the position corresponding to the current voltage signal. The piston seal ring 14 is made of conductive rubber composite material, and forms a high-sensitivity strain sensor based on the piezoresistive effect, and forms a dynamic seal with the groove at the end of the piston rod and the inner wall of the cylinder. Two metal contacts 13 are symmetrically arranged at the piston groove to detect the resistance change of the piston seal ring, and the deformation of the piston seal ring is obtained based on the piezoresistive effect.

[0039] In this embodiment, a pair of sensor channels 15 are symmetrically arranged inside the piston, one end of the connecting wire 17 is connected to the metal contact, and the other end passes through the sensor channel 15 and the displacement sensor sleeve 16 to connect to the gap of the inner wall of the piston and the internal circuit of the displacement sensor 18, so that the sealing ring resistance change signal is transmitted to the control test box through the plug, and then the deformation size of the piston sealing ring is monitored in real time. Since the leakage in the two chambers of the cylinder will cause the piston sealing ring to deform, the deformation size of the sealing ring can reflect the degree of leakage in the working chamber of the cylinder. The length of the connecting wire 17 is redundant so that the piston displacement does not affect the signal transmission.

[0040] In this embodiment, the control test box controls the oil pressure and flow changes in the cylinder cavity through the servo valve according to the amplitude of the signal generator signal. The control test box simultaneously receives the compensation feedback signals of the displacement sensor and the piston sealing ring strain sensor to form a closed-loop control to keep the piston rod position stable during the static test.

[0041] Example 2 like Figures 1 to 6 As shown, the present invention provides a static test method for a compensating hydraulic actuator, comprising: The hydraulic actuator 12 is connected to the universal testing machine through the earring fixture 10 at the protruding end and the earring fixture 11 at the fixed end. After the control test box receives the voltage signal given by the signal generator, it outputs a control signal to the servo valve. The servo valve controls the actuator piston to move to the position corresponding to the signal value by adjusting the oil pressure and flow rate in the cavity of the hydraulic actuator 12. Then the universal testing machine 19 applies a load to the hydraulic actuator 12 through the fixture. During this process, the displacement sensor 18 transmits the displacement signal of the piston in the cylinder to the control test box through the plug 9. In addition, during the control process, the oil pressure difference between the two chambers inside the hydraulic actuator 12 will cause the piston seal 14 in the piston groove to deform and leak, which will cause the oil pressure in the cavity to be unstable and the piston position to shift. The piston seal 14 made of conductive rubber composite material can form a strain sensor, and the piston seal deformation signal is transmitted to the control test box through the contact 13 and the plug 9. The control test box receives the displacement signal of the piston and the deformation signal feedback of the sealing ring to form a closed-loop control, and further adjusts the oil pressure and flow to ensure the stability of the piston position during the static test.

[0042] In summary, the present invention adjusts the oil pressure and flow in the cavity of the hydraulic actuator through a servo valve, and can accurately control the moving position of the piston, meeting the strict requirements of the static test on displacement accuracy. The displacement sensor transmits the displacement signal of the piston in the cylinder to the control test box in real time to ensure accurate monitoring of the piston position. The piston seal ring made of conductive rubber composite material is used as a strain sensor, which can feedback the deformation signal of the seal ring in real time to form a closed-loop control system. This design can adjust the oil pressure and flow in time, effectively compensate for the piston position offset caused by the deformation of the seal ring, and ensure the stability of the piston position during the test. Through closed-loop control, the system can automatically adjust to offset the unstable piston position caused by the internal oil pressure difference, thereby improving the accuracy and reliability of the static test. The traditional piston seal ring may cause leakage and unstable pressure due to deformation, while the seal ring made of conductive rubber composite material not only has a sealing function, but also can be used as a strain sensor, realizing multi-functional integration. In addition, through connection methods such as plugs and contacts, signal transmission and system expansion are convenient.

[0043] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0044] In addition, it should be understood that although this specification is described in accordance with the implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art. The above content is only to illustrate the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution according to the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A static test device for a compensating hydraulic actuator, characterized in that: It comprises an earring fixture (10) at the extension end of the hydraulic actuator, an earring fixture (11) at the fixed end, and a servo control part; One end of the protruding end earring fixture (10) is used to connect with the protruding end earring of the hydraulic actuator (12), and the other end is used to connect with the universal testing machine (19); one end of the fixed end earring fixture (11) is used to connect with the fixed end earring of the hydraulic actuator (12), and the other end is used to connect with the universal testing machine; the servo control part includes a sensor, a signal generator, a control test box and a servo valve, the sensor includes a strain sensor formed by a piston sealing ring (14) and a displacement sensor (18) inside the piston; after receiving the voltage signal given by the signal generator, the control test box outputs a control signal to the servo valve, and the servo valve controls the actuator piston to move to a position corresponding to the signal value by adjusting the oil pressure and flow rate in the cavity of the hydraulic actuator (12).

2. A static test device for a compensating hydraulic actuator according to claim 1, characterized in that: The protruding end earring clamp (10) adopts a claw-type structure (4) and is provided with bolt holes for connecting with the protruding end earring of the hydraulic actuator (12).

3. A static test device for a compensating hydraulic actuator according to claim 2, characterized in that: The other end of the protruding end earring fixture (10) is provided with a thread and a pin hole, and the pin passes through the pin hole so that the protruding end earring fixture (10) is connected to the universal testing machine (19), and the clamp (6) cooperates with the thread to apply a pre-tightening force to ensure that the fixture (10) and the universal testing machine (19) are firmly connected.

4. A static test device for a compensating hydraulic actuator according to claim 1, characterized in that: One end of the fixed end earring clamp (11) is provided with a bolt hole and is connected to the fixed end earring of the hydraulic actuator (12) through a bolt, and the other end of the bolt is matched with a nut.

5. A static test device for a compensating hydraulic actuator according to claim 4, characterized in that: The other end of the fixed end earring clamp (11) is provided with a thread and a pin hole, and the pin passes through the pin hole to connect the extended end earring clamp (10) with the universal testing machine (19), and the clamp (6) cooperates with the thread to apply a pre-tightening force to ensure that the clamp (10) and the universal testing machine (19) are firmly connected.

6. A static test device for a compensating hydraulic actuator according to claim 1, characterized in that: The fixed end of the hydraulic actuator is a double-ear structure, the extended end is a single-ear structure, and the maximum load is 10 tons.

7. A static test device for a compensating hydraulic actuator according to claim 1, characterized in that: The sealing ring (14) at the groove of the hydraulic actuator piston is prepared from a conductive rubber composite material.

8. The static test device for a compensating hydraulic actuator according to claim 1, characterized in that: A pair of sensor contacts (13) are symmetrically arranged at the bottom of the groove of the hydraulic actuator piston; a hole (15) is symmetrically arranged inside the actuator piston; a connecting wire (17) is arranged inside the actuator piston, one end of which is connected to the metal contact (13), and the other end passes through the hole in the piston and is connected to the internal circuit of the displacement sensor (18) through the gap between the sensor sleeve (16) and the inner wall of the piston.

9. A static test device for a compensating hydraulic actuator according to claim 8, characterized in that: The resistance change signal of the piston seal ring (14) is transmitted to the servo control box through the plug (9). The servo control box determines the deformation of the seal ring based on the piezoresistive effect and applies a feedback signal to the servo valve. The servo valve adjusts the oil pressure and flow rate in the actuator cavity according to the signal to compensate for the leakage at the seal ring.

10. A static test method for a compensated hydraulic actuator, characterized in that: The method is based on a static test device for a compensating hydraulic actuator as described in claim 9, comprising: During the test, the hydraulic actuator (12) is connected to the universal testing machine through the earring fixture (10) at the extended end and the earring fixture (11) at the fixed end. After the control test box receives the voltage signal given by the signal generator, it outputs a control signal to the servo valve. The servo valve controls the actuator piston to move to a position corresponding to the signal value by adjusting the oil pressure and flow rate in the cavity of the hydraulic actuator (12). Subsequently, the universal testing machine (19) applies a load to the hydraulic actuator (12) through the fixture. During this process, the displacement sensor (18) transmits the displacement signal of the piston in the cylinder through the plug (9). The piston seal ring (14) is transmitted to the control test box; during the control process, the oil pressure difference between the two chambers inside the hydraulic actuator (12) will cause the piston seal ring (14) in the piston groove to deform and leak, thereby causing the oil pressure in the chamber to be unstable and the piston position to shift; the piston seal ring (14) can form a strain sensor, and transmit the piston seal ring deformation signal to the control test box through the contact (13) and the plug (9); the control test box receives the piston displacement signal and the seal ring deformation signal feedback, forms a closed-loop control, and further adjusts the oil pressure and flow to ensure the stability of the piston position during the static test.

Images