A static test method and apparatus for a compensated hydraulic actuator

Abstract

This invention discloses a compensating method and apparatus for static testing of hydraulic actuators. The apparatus considers leakage of the sealing ring during the static test of the actuator and uses a servo control system for compensation control to obtain more accurate measurement results. The testing apparatus includes a static test structure and a servo control system. The static test structure includes a special clamp adapted to the actuator's lugs for a secure connection between the actuator and the testing machine. The servo control system includes sensors, a signal generator, and a control test chamber. The piston sealing ring is made of conductive rubber composite material, forming a highly sensitive strain sensor for feedback of sealing ring deformation data. The servo control system compensates for the piston displacement, effectively ensuring the stability of the piston position during the test. Compared to traditional servo control based solely on piston displacement feedback, this invention is more accurate and faster, ensuring the reliability of the static test results.

Description

Technical Field

[0001] This invention relates to the field of static testing technology, and in particular to a method and apparatus for static testing of a compensated hydraulic actuator. Background Technology

[0002] In the research and development of hydraulic actuators, mechanical properties such as static strength, vibration resistance, and impact resistance are crucial indicators, directly determining the product's performance. Therefore, during the actuator's research and design phase, appropriate tests must be conducted based on the external loads the actuator may experience during operation, such as static tests, pressure tests, random vibration tests, and impact tests. Static tests and pressure tests are static tests, primarily used to verify whether the actuator's structural strength meets the load requirements. These tests serve as a prerequisite for dynamic testing and are extremely important for the design and development of the actuator.

[0003] However, there are currently few static testing systems and methods for hydraulic actuators. Existing static testing equipment requires separate design for the structure and operating characteristics of hydraulic actuators, resulting in long development cycles and high costs. Universal testing machines, which integrate tensile and compression testing functions, can be equipped with specially designed fixtures to perform tensile and compression tests on actuators. They are easy to install and disassemble, and can be adapted to various models of hydraulic actuators for static testing. Furthermore, current static tests for actuators all employ closed-loop control systems based on piston displacement feedback. However, this control method does not consider oil leakage within the actuator cylinder, resulting in low control accuracy and slow speed. Therefore, designing a convenient, adaptable testing device and a highly accurate, rapid-response testing method for static testing of hydraulic actuators is of great significance.

[0004] During the static test of the actuator, the pressure difference between the two chambers of the actuator cylinder can cause oil leakage through the sealing ring, resulting in piston position displacement. Currently, the application of conductive rubber composite materials in the field of intelligent sensing has shown initial success. Piston sealing rings made from this material can, while fulfilling the sealing function, provide feedback on the deformation of the sealing ring and compensate for the oil pressure through a servo control system, maintaining piston position stability and ensuring reliable test results. Summary of the Invention

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

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A static testing device for a compensated hydraulic actuator includes an extension end clevis clamp, a fixed end clevis clamp, and a servo control unit.

[0008] One end of the protruding end ear clamp is used to connect to the protruding end ear of the hydraulic actuator, and the other end is used to connect to the universal testing machine. One end of the fixed end ear clamp is used to connect to the fixed end ear of the hydraulic actuator, and the other end is used to connect to the universal testing machine. The servo control part includes sensors, signal generators, control test chambers, and servo valves. The sensors include strain sensors formed by piston seals and displacement sensors inside the piston. After receiving the voltage signal given by the signal generator, the control test chamber 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.

[0009] A further improvement of the present invention is that the protruding end earring clamp adopts a claw-shaped structure and is provided with bolt holes for connection with the protruding end earring of the hydraulic actuator.

[0010] A further improvement of the present invention is that the other end of the protruding earring clamp is provided with a thread and a pin hole. The pin passes through the pin hole to connect the protruding earring clamp to the universal testing machine. The clamp and the thread engage to apply a preload to ensure that the clamp is securely connected to the universal testing machine.

[0011] A further improvement of the present invention is that one end of the fixed end earring clamp is provided with a bolt hole and is connected to the fixed end earring of the hydraulic actuator by a bolt, and the other end of the bolt is engaged with a nut.

[0012] A further improvement of the present invention is that the other end of the fixed end earring clamp is provided with a thread and a pin hole. The pin passes through the pin hole to connect the protruding end earring clamp to the universal testing machine. The clamp and the thread engage to apply a preload force to ensure that the clamp is firmly connected to the universal testing machine.

[0013] A further improvement of the present invention is that the fixed end of the hydraulic actuator has a double-ear structure, the extended end has a single-ear structure, and the maximum load is 10 tons.

[0014] A further improvement of the present invention is that the sealing ring at the piston groove of the hydraulic actuator is made of conductive rubber composite material.

[0015] 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, one end of which is connected to the metal contact, and the other end passes through the inner channel of 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.

[0016] A further improvement of the present invention is that the resistance change signal of the piston seal ring is transmitted to the servo control box through the plug. 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 leakage at the seal ring.

[0017] A static test method for a compensated hydraulic actuator, the method being based on the aforementioned static test apparatus for a compensated hydraulic actuator, comprising:

[0018] During the test, the hydraulic actuator is connected to the universal testing machine via the extended end clevis clamp and the fixed end clevis clamp. After receiving the voltage signal given by the signal generator, the control test chamber outputs a control signal to the servo valve. The servo valve controls the piston of the actuator to move to the position corresponding to the signal value by adjusting the oil pressure and flow rate in the hydraulic actuator cavity. Subsequently, the universal testing machine applies a load to the hydraulic actuator through the clamps. During this process, the displacement sensor transmits the displacement signal of the piston in the cylinder to the control test chamber through the plug. During the control process, the hydraulic pressure difference between the two chambers of the hydraulic actuator will cause the piston seal ring in the piston groove to deform and leak, which will lead to unstable oil pressure in the cavity and displacement of the piston position. The piston seal ring can act as a strain sensor, transmitting the piston seal ring deformation signal to the control test chamber through the contact and plug. The control test chamber receives the piston displacement signal and the seal ring deformation signal feedback to form a closed loop control, further adjusting the oil pressure and flow rate to ensure the stability of the piston position during the static test.

[0019] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0020] 1. In this invention, when the device is in use, the hydraulic actuator can be securely connected to the universal testing machine clamp during static testing by means of the clamps at the fixed end and output end of the hydraulic actuator, while keeping the actuator lug shaft stable during the application of load.

[0021] 2. A method for arranging piston seal ring strain sensors is provided. In this invention, a path is formed by the metal contact at the bottom of the piston groove, the wire at the internal channel of the piston, and the piston seal ring made of conductive rubber composite material, so that the resistance change signal of the piston seal ring can be transmitted to the control test box through the plug.

[0022] 3. A pressure relief compensation method is provided. In this invention, when the device is in use, based on the piezoresistive effect, the servo control box can determine the deformation of the piston sealing ring according to the change in the resistance of the piston sealing ring, thereby obtaining 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. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the protruding end earring clamp structure;

[0025] Figure 2 This is a schematic diagram of the fixed-end earring clamp structure;

[0026] Figure 3 A schematic diagram of the assembly structure of the fixture and actuator;

[0027] Figure 4 This is a schematic diagram of the sensor arrangement in the cross-section of the actuator;

[0028] Figure 5 This is a schematic diagram of the actuator and the testing machine assembly.

[0029] Figure 6 This is a system organization diagram.

[0030] Explanation of reference numerals in the attached figures:

[0031] 1. Bolt hole; 2. Thread; 3. Pin hole; 4. Claw structure; 5. Pin; 6. Clamp; 7. Bolt; 8. Nut; 9. Plug; 10. Extending end ear clamp; 11. Fixed end ear clamp; 12. Hydraulic actuator; 13. Metal contact; 14. Piston seal ring; 15. Sensor channel; 16. Displacement sensor sleeve; 17. Connecting wire; 18. Displacement sensor; 19. Universal testing machine; 20. Universal testing machine fixed end chuck. Detailed Implementation

[0032] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0033] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0034] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0035] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0036] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0037] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0038] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0039] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0040] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0041] Example 1

[0042] like Figures 1 to 5 As shown, the present invention provides a static testing device for a compensated hydraulic actuator, comprising a hydraulic actuator extension end clevis clamp 10, a fixed end clevis clamp 11, and a servo control unit. One end of the extension end clevis clamp 10 is used to connect to the extension end clevis of the hydraulic actuator 12, and the other end is used to connect to a universal testing machine 19. One end of the fixed end clevis clamp 11 is used to connect to the fixed end clevis of the hydraulic actuator 12, and the other end is used to connect to the universal testing machine. The servo control unit includes sensors, a signal generator, a control test chamber, and a servo valve. The sensors include 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 chamber 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.

[0043] This invention specifically includes a special fixture and servo control unit designed for universal testing machines and hydraulic actuators. Combined with... Figures 1 to 3 As shown, the designed special fixture includes a protruding end ear clamp 10 and a fixed end ear clamp 11 for the hydraulic actuator. The hydraulic actuator 12 is connected to the universal testing machine 19 through the protruding end ear clamp 10 and the fixed end ear clamp; combined with Figures 3 to 5 As shown, the servo control section includes sensors, signal generators, control test chambers, and servo valves.

[0044] In this embodiment, the protruding end earring clamp 10 adopts a claw-shaped structure 4 based on the three-point positioning principle, and is provided with bolt hole 1 to connect to the protruding end earring of the hydraulic actuator 12 through bolt 7 and nut 8.

[0045] In this embodiment, the other end of the protruding 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 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 and the universal testing machine 19 are firmly connected.

[0046] In this embodiment, the upper end of the fixed end ear clamp 11 is provided with bolt hole 1 and is connected to the fixed end ear of the hydraulic actuator 12 by bolt 7. The other end of the bolt 7 is engaged with nut 8 to ensure stable connection during the test.

[0047] In this embodiment, the other end of the fixed end earring clamp 11 is provided with a thread 2 and a pin hole 3, and its connection with the universal testing machine 19 is the same as that of the extended end earring.

[0048] In this embodiment, the fixed end of the hydraulic actuator has a double-ear structure, the extended end has a single-ear structure, and the maximum load is 10 tons.

[0049] In this embodiment, the sensors in the servo control section include a strain sensor formed by the piston seal ring 14 and a displacement sensor 18 inside the piston. A signal generator sends a DC voltage signal to the control test chamber, which receives the signal and transmits the control signal to the servo valve. The servo valve controls the piston displacement by changing the oil pressure and flow rate until the piston is held at the position corresponding to the current voltage signal. The piston seal ring 14 is made of conductive rubber composite material, forming a highly sensitive strain sensor based on the piezoresistive effect, and forming a dynamic seal with the piston rod end groove and the inner wall of the cylinder. Two symmetrical metal contacts 13 are arranged at the piston groove to detect changes in the piston seal ring resistance, and the deformation of the piston seal ring is determined based on the piezoresistive effect.

[0050] 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 a metal contact, and the other end passes through the sensor channel 15 and the displacement sensor sleeve 16, connecting to the gap in the piston's inner wall and the internal wiring of the displacement sensor 18. This allows the signal of the seal ring resistance change to be transmitted to the control test chamber through the plug, thereby monitoring the deformation of the piston seal ring in real time. Since leakage in the two cavities of the cylinder will cause deformation of the piston seal ring, the degree of leakage in the working cavity of the cylinder can be reflected by the deformation of the seal ring. The length of the connecting wire 17 is redundant so that piston displacement does not affect signal transmission.

[0051] In this embodiment, the control test chamber controls the oil pressure and flow rate changes in the cylinder cavity through a servo valve based on the magnitude of the signal amplitude from the signal generator. The control test chamber simultaneously receives compensation feedback signals from the displacement sensor and the piston seal strain sensor to form a closed-loop control, maintaining the piston rod position stable during the static test.

[0052] Example 2

[0053] like Figures 1 to 6 As shown, the present invention provides a static test method for a compensated hydraulic actuator, comprising:

[0054] The hydraulic actuator 12 is connected to the universal testing machine via the extended end clevis clamp 10 and the fixed end clevis clamp 11. After receiving the voltage signal from the signal generator, the control test chamber outputs a control signal to the servo valve. The servo valve controls the piston of the actuator 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. Subsequently, the universal testing machine 19 applies a load to the hydraulic actuator 12 through the clamps. During this process, the displacement sensor 18 transmits the displacement signal of the piston in the cylinder to the control test chamber through the plug 9. In addition, during the control process, the hydraulic pressure difference between the two cavities inside the hydraulic actuator 12 can cause the piston seal ring 14 in the piston groove to deform and leak, resulting in unstable oil pressure in the cavity and displacement of the piston position. The piston seal ring 14, made of conductive rubber composite material, can form a strain sensor, transmitting the piston seal ring deformation signal to the control test chamber through the contact 13 and the plug 9. The control chamber receives feedback signals from the piston displacement and the sealing ring deformation to form a closed-loop control, further adjusting the oil pressure and flow rate to ensure the stability of the piston position during the static test.

[0055] In summary, this invention uses a servo valve to adjust the oil pressure and flow rate within the hydraulic actuator cavity, enabling precise control of the piston's movement position and meeting the stringent displacement accuracy requirements of static testing. A displacement sensor transmits the piston's displacement signal within the cylinder to the control test chamber in real time, ensuring accurate monitoring of the piston position. A piston seal ring made of conductive rubber composite material serves as a strain sensor, providing real-time feedback on seal ring deformation signals, forming a closed-loop control system. This design allows for timely adjustment of oil pressure and flow rate, effectively compensating for piston position deviations caused by seal ring deformation and ensuring piston position stability during the test. Through closed-loop control, the system automatically adjusts to counteract piston position instability caused by internal oil pressure differentials, thereby improving the accuracy and reliability of static testing. Traditional piston seal rings may leak and experience pressure instability due to deformation, while the seal ring made of conductive rubber composite material not only provides sealing but also functions as a strain sensor, achieving multi-functional integration. Furthermore, the connection methods, such as plugs and contacts, facilitate signal transmission and system expansion.

[0056] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the scope of the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0057] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A static testing device for a compensated hydraulic actuator, characterized in that, Includes a hydraulic actuator extension end ear clamp (10), a fixed end ear clamp (11), and a servo control unit; One end of the protruding end ear clamp (10) is used to connect with the protruding end ear 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 ear clamp (11) is used to connect with the fixed end ear 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 the piston seal 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. The servo valve controls the piston of the actuator 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).

2. The static testing device for a compensated hydraulic actuator according to claim 1, characterized in that, The protruding end earring clamp (10) adopts a claw-shaped structure (4) and is provided with bolt holes to connect with the protruding end earring of the hydraulic actuator (12).

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

4. The static testing device for a compensated 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) by a bolt. The other end of the bolt is engaged with a nut.

5. The static testing device for a compensated 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. The pin passes through the pin hole to connect the extended end earring clamp (10) with the universal testing machine (19). The clamp (6) engages with the thread and applies a pre-tightening force to ensure that the clamp (10) and the universal testing machine (19) are firmly connected.

6. The static testing device for a compensated hydraulic actuator according to claim 1, characterized in that, The hydraulic actuator has a double-ear structure at the fixed end and a single-ear structure at the extended end, with a maximum load of 10 tons.

7. The static testing device for a compensated hydraulic actuator according to claim 1, characterized in that, The sealing ring (14) at the piston groove of the hydraulic actuator is made of conductive rubber composite material.

8. The static testing device for a compensated 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 channel (15) is symmetrically arranged inside the actuator piston; a connecting wire (17) is provided inside the actuator piston, one end of which is connected to the metal contact (13), and the other end passes through the inner channel of 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 testing device for a compensated 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 leakage at the seal ring.

10. A static test method for a compensated hydraulic actuator, characterized in that, This method is based on the static testing device for a compensated hydraulic actuator as described in claim 9, comprising: During the test, the hydraulic actuator (12) is connected to the universal testing machine via the extended end ear clamp (10) and the fixed end ear clamp (11). After receiving the voltage signal given by the signal generator, the control test chamber outputs a control signal to the servo valve. The servo valve controls the piston of the actuator 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). Subsequently, the universal testing machine (19) applies a load to the hydraulic actuator (12) through the clamp. During this process, the displacement sensor (18) transmits the displacement signal of the piston in the cylinder through the plug (9). The signal is transmitted to the control test chamber. During the control process, the hydraulic pressure difference between the two chambers of the hydraulic actuator (12) will cause the piston seal ring (14) in the piston groove to deform and leak, which will lead to unstable oil pressure in the chamber and displacement of the piston position. The piston seal ring (14) can form a strain sensor and transmit the piston seal ring deformation signal to the control test chamber through the contact (13) and plug (9). The control test chamber receives the piston displacement signal and the seal ring deformation signal feedback to form a closed loop control, further adjust the oil pressure and flow rate, and ensure the stability of the piston position during the static test.

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