Pre-loading three-cavity hydraulic cylinder for high-low cycle fatigue test and control method
By improving the three-chamber hydraulic cylinder and its control method, the problems of large flow demand and poor control accuracy of traditional hydraulic cylinders under high and low cycle combined loading are solved, achieving efficient load control, meeting the accuracy requirements of high and low cycle fatigue tests, and reducing test costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XIAN LILI TECH IND GENERAL CO
- Filing Date
- 2026-02-09
- Publication Date
- 2026-04-17
AI Technical Summary
Traditional dual-chamber hydraulic cylinders have high flow requirements when subjected to high and low cycle combined loading. The accumulator volume of a single closed-loop control three-chamber hydraulic cylinder affects control accuracy, while dual closed-loop control loops suffer from mutual interference and poor control accuracy.
A preloaded three-chamber hydraulic cylinder for high and low cycle fatigue testing is adopted, including chambers A, B, and C. By using load sensors and differential pressure sensors to provide feedback data, combined with servo valves in chamber C and chambers A/B, dual closed-loop control is achieved. Pressure fluctuations are eliminated through accumulators in chamber C and high and low pressure accumulators, and unloading is achieved through pressure relief solenoid valves, thereby improving control accuracy.
It reduces test power consumption, saves costs, improves the control accuracy of high and low cycle composite load loading, and meets the load spectrum requirements of high and low cycle fatigue tests.
Smart Images
Figure CN121876013A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a hydraulic cylinder-controlled testing device, specifically a preloaded three-chamber hydraulic cylinder and its control method for high and low cycle fatigue testing. Background Technology
[0002] In various testing equipment requiring preloading, such as shaft fatigue load tests and vibration tables, traditional dual-chamber hydraulic cylinders are commonly used as force loading devices. However, traditional dual-chamber hydraulic cylinders suffer from high flow rate requirements when used for high- and low-cycle combined loading. Three-chamber hydraulic cylinders, by introducing a third chamber (C chamber), effectively solve the problems of high hydraulic oil flow rate requirements and poor control accuracy in high-cycle vibration encountered by traditional dual-chamber hydraulic cylinders.
[0003] There are two methods for loading control of a three-chamber hydraulic cylinder: single-loop control and double-loop control. Single-loop control involves setting up an accumulator in the third chamber. The size of the accumulator directly affects the control accuracy, requiring precise calculation of the accumulator volume. A load sensor at the piston rod tip feeds back to the servo valves controlling the first two chambers of the three-chamber hydraulic cylinder, forming a single closed-loop control. This method is unsuitable for conditions involving frequent loading and unloading of the preload chamber (Channel C) and suffers from high hydraulic oil flow requirements due to the accumulator's charging and discharging pressure. Double-loop control adds a servo valve, using the preload chamber pressure as feedback. The preload chamber pressure is controlled in a closed loop, with the servo valve's control command being the pressure value corresponding to the preload load. The two closed-loop control loops are independent, leading to mutual interference and poor control accuracy. In summary, the existing experimental setup has the following shortcomings: Traditional dual-chamber hydraulic cylinders have the problem of high flow rate requirement when used for high and low cycle composite loading; In a single closed-loop controlled three-chamber hydraulic cylinder, the volume of the accumulator directly affects the control accuracy, requiring precise calculation of the accumulator volume. Currently, the two closed-loop control loops of the three-chamber hydraulic cylinder are independent, which leads to mutual interference and poor control accuracy. Summary of the Invention
[0004] The purpose of this invention is to provide a preloaded three-chamber hydraulic cylinder and its control method for high- and low-cycle fatigue testing. This invention is applied to composite load conditions, similar to those in shaft testing machines, where the load spectrum consists of a large-amplitude low-cycle static load and a small-amplitude high-cycle dynamic load. It addresses the problem of high flow rate requirements in traditional dual-chamber hydraulic cylinders used in such testing machines, thereby reducing test power consumption and saving test costs. Furthermore, it improves the control accuracy of traditional three-chamber hydraulic cylinders for high- and low-cycle composite loads by addressing the issue of low precision.
[0005] To achieve the above objectives, the technical solution adopted by the present invention is: a preloaded three-chamber hydraulic cylinder for high and low cycle fatigue testing, comprising a three-chamber hydraulic cylinder, a load sensor, a differential pressure sensor, and a protection module valve group. The three-chamber hydraulic cylinder includes chamber A, chamber B, and chamber C. The protection module valve group includes a chamber C accumulator, a high-pressure accumulator, a low-pressure accumulator, a chamber C pressure relief solenoid valve, chamber A / B pressure relief solenoid valves, a chamber C servo valve, chamber A / B servo valves, an oil inlet, an oil outlet, a filter, and a valve body. The oil inlet is connected to a filter, and the oil inlet and filter are installed together on the valve body. Inside the valve body, the oil inlet is divided into two branches, which are respectively connected to the C-cavity servo valve and the A / B-cavity servo valve. The C-cavity servo valve and the A / B-cavity servo valve are respectively connected to the three-cavity hydraulic cylinder and are both connected to the oil outlet. The C-cavity accumulator is installed on the C-cavity of the three-cavity hydraulic cylinder. The high-pressure accumulator is installed on the oil inlet line, and the low-pressure accumulator is installed on the oil return line. The C-cavity pressure relief solenoid valve is installed between the C-cavity servo valve and the three-cavity hydraulic cylinder, and the A / B-cavity pressure relief solenoid valve is installed between the A-cavity and B-cavities. Both the load sensor and the differential pressure sensor are mounted on the three-chamber hydraulic cylinder. The load sensor is used to measure the output force of the three-chamber hydraulic cylinder and feeds back the measured force value to the controller of the A / B chamber servo valve. The differential pressure sensor outputs the hydraulic pressure difference between chamber A and chamber B and feeds back the differential pressure data to the controller of the C chamber servo valve.
[0006] A further improvement is that the three-chamber hydraulic cylinder also includes a built-in piston and piston rod.
[0007] A further improvement is that the working areas of chambers A and B are the annular areas formed by the piston and piston rod, and the hydraulic parameters of chambers A and B are symmetrical. Chamber C is a separate working chamber with a working area equal to the area of the piston rod.
[0008] A further improvement is that the effective area of cavity C is larger than that of cavities A and B.
[0009] A further improvement is that one end of the load sensor is connected to the test specimen using a screw, which is used to detect the magnitude of the load applied to the test specimen in real time.
[0010] A further improvement is that the C-cavity servo valve and the A / B-cavity servo valve are used to control the hydraulic oil. Each servo valve includes four ports: P, T, A, and B. Port P is connected to the oil supply line, port T is connected to the oil return line, and ports A and B are connected to the actuator, a three-cavity hydraulic cylinder, to control the flow rate and pressure of the hydraulic oil in the A, B, and C cavities of the three-cavity hydraulic cylinder, so that the load of the load spectrum output by the three-cavity hydraulic cylinder acts on the test piece to complete the load loading.
[0011] A further improvement is that the C-cavity accumulator, high-pressure accumulator, and low-pressure accumulator are used to eliminate pressure fluctuations and replenish oil; the C-cavity pressure relief solenoid valve and the A / B-cavity pressure relief solenoid valve are used for unloading the three-cavity hydraulic cylinder.
[0012] The present invention also provides a control method for a preloaded three-chamber hydraulic cylinder used in high- and low-cycle fatigue testing, comprising the following steps: The feedback data in the control closed loop of the three-chamber hydraulic cylinder C chamber is collected, where the feedback data is the pressure data of the differential pressure sensor between the three-chamber hydraulic cylinder A chamber and B chamber; The feedback data in the control closed loop of the three-chamber hydraulic cylinder A and B chambers is collected, and the feedback data is the load data of the load sensor. The control command data for controlling chamber C of the three-chamber hydraulic cylinder is compared in real time with the pressure data from the differential pressure sensors of chambers A and B of the three-chamber hydraulic cylinder to improve the control accuracy of the high and low cycle fatigue test of the three-chamber cylinder. By comparing the control command data for chambers A and B of the three-chamber hydraulic cylinder with the load data from the load sensor in real time, the control accuracy of the high- and low-cycle fatigue test of the three-chamber cylinder is improved.
[0013] In another implementation, the data of the control command three controlling the load of the C cavity is compared in real time with the feedback data in the control closed loop of the control of the C cavity of the three-cavity hydraulic cylinder, wherein the feedback data is the pressure data of the pressure sensor of the C cavity of the three-cavity hydraulic cylinder, thereby improving the control accuracy of the high and low cycle fatigue test of the three-cavity cylinder.
[0014] The beneficial technical effects of this invention are as follows: the effective area of cavity C is larger than that of cavities A and B. C cavity is used to output a large-amplitude low-frequency trapezoidal wave load, while cavities A and B are used to output a small-amplitude high-frequency sine wave load. The load sensor is used to measure the output force of the three-cavity hydraulic cylinder and feeds the measured force value back to the controller of the A / B cavity servo valve. The differential pressure sensor outputs the hydraulic pressure difference between cavities A and B and feeds the differential pressure data back to the controller of the C cavity servo valve. The control command for cavity C of the three-cavity hydraulic cylinder is 0; the other control command is used to control cavities A and B of the three-cavity hydraulic cylinder. Control command two is a combined load of a large-amplitude low-frequency trapezoidal wave load and a small-amplitude high-frequency sinusoidal wave load. This addresses the issue that the load spectrum in high-low frequency fatigue tests is composed of a large-amplitude low-frequency trapezoidal wave load and a small-amplitude high-frequency sinusoidal wave load. When traditional two-chamber hydraulic cylinders are used for high-low frequency composite loading, the effective working area of the piston is large in order to meet the total load requirements of high and low frequencies. When loading small-amplitude high-frequency sinusoidal wave loads, a large amount of flow is consumed. This also addresses the problem of low accuracy in the high-low frequency composite load loading control method of traditional three-chamber hydraulic cylinders. This reduces test power consumption and saves test costs. Attached Figure Description
[0015] Figure 1 Schematic diagram of the control principle of the three-chamber hydraulic cylinder in Embodiment 1 of the present invention; Figure 2 Schematic diagram of the control principle of the three-chamber hydraulic cylinder in Embodiment 2 of the present invention; Figure 3 Front view of the three-chamber hydraulic cylinder structure of the present invention; Figure 4 Top view of the three-chamber hydraulic cylinder structure of the present invention; Figure 5 Cross-sectional view of the three-chamber hydraulic cylinder structure of the present invention; Figure 6 A / B cavity control command load spectrum curve of the present invention; Figure 7 The data curve of the C-cavity load control command in Embodiment 1 of the present invention; Figure 8 The data curve of the C-cavity load control command in Embodiment 2 of the present invention; Reference numerals: 100—Three-chamber hydraulic cylinder, 101—Cavity C, 102—Cavity B, 103—Cavity A, 104—Rear hydrostatic bearing, 105—Front hydrostatic bearing, 106—Hydrostatic bearing inlet, 107—Hydrostatic bearing outlet, 108—Piston, 109—Piston rod, 200—Test specimen, 301—Load sensor, 302—Differential pressure sensor, 303—Pressure sensor, 401—Cavity C accumulator, 402—High-pressure accumulator, 403—Low-pressure accumulator, 501—Cavity C pressure relief solenoid valve, 502—A / B cavity pressure relief solenoid valve, 601—Cavity C servo valve, 602—A / B cavity servo valve, 701—Control command one, 702—Control command two, 703—Control command three, 801—Inlet, 802—Outlet, 900—Filter, 1000—Valve body. Detailed Implementation
[0016] The present application will be further described in detail below with reference to the accompanying drawings.
[0017] like Figure 3-5 As shown, a preloaded three-chamber hydraulic cylinder for high and low cycle fatigue testing includes a three-chamber hydraulic cylinder 100, a load sensor 301, a differential pressure sensor 302, and a protection module valve group. The three-chamber hydraulic cylinder 100 includes chamber A 103, chamber B 102, and chamber C 101. The protection module valve group includes a chamber C accumulator 401, a high-pressure accumulator 402, a low-pressure accumulator 403, a chamber C pressure relief solenoid valve 501, a chamber A / B pressure relief solenoid valve 502, a chamber C servo valve 601, a chamber A / B servo valve 602, an oil inlet 801, an oil outlet 802, a filter 901, and a valve body 1000. The oil inlet 801 is connected to the filter 901. The oil inlet 801 and the filter 901 are installed together on the valve body 1000. Inside the valve body 1000, the oil inlet is divided into two branches, which are respectively connected to the C-cavity servo valve 601 and the A / B-cavity servo valve 602. The C-cavity servo valve 601 and the A / B-cavity servo valve 602 are respectively connected to the three-cavity hydraulic cylinder 100 and are both connected to the oil outlet 802. The C-cavity accumulator 401 is installed on the C-cavity 101 of the three-cavity hydraulic cylinder. The high-pressure accumulator 402 is installed on the oil inlet line, and the low-pressure accumulator 403 is installed on the oil return line. The C-cavity pressure relief solenoid valve 501 is installed between the C-cavity servo valve 601 and the three-cavity hydraulic cylinder 100. The A / B-cavity pressure relief solenoid valve 502 is installed between the A-cavity 103 and the B-cavity 102. Both the load sensor 301 and the differential pressure sensor 302 are mounted on the three-chamber hydraulic cylinder 100. The load sensor 301 is used to measure the output force of the three-chamber hydraulic cylinder 100 and feeds back the measured force value to the controller of the A / B chamber servo valve 602. The differential pressure sensor 302 outputs the hydraulic pressure difference between chamber A 103 and chamber B 102 and feeds back the differential pressure data to the controller of the C chamber servo valve 601.
[0018] The three-chamber hydraulic cylinder 100 also includes a built-in piston 108 and piston rod 109.
[0019] The working area of cavity A 103 and cavity B 102 is the annular area formed by piston 108 and piston rod 109, and the hydraulic parameters of cavity A 103 and cavity B 102 are symmetrical. C cavity 101 is a separate working cavity, and its working area is the area of piston rod 109.
[0020] The effective area of cavity C 101 is greater than that of cavity A 103 and cavity B 102.
[0021] One end of the load sensor 301 is connected to the test specimen 200 by a screw, and is used to detect the magnitude of the load applied to the test specimen 200 in real time.
[0022] The C-cavity servo valve 601 and A / B-cavity servo valve 602 are used to control the hydraulic oil. Each servo valve includes four ports: P, T, A, and B. Port P is connected to the oil supply line, port T is connected to the oil return line, and ports A and B are connected to the actuator, the three-cavity hydraulic cylinder 100. These valves are used to control the flow rate and pressure of the hydraulic oil in the A-cavity 103, B-cavity 102, and C-cavity 101 of the three-cavity hydraulic cylinder 100, so that the load of the load spectrum output by the three-cavity hydraulic cylinder 100 is applied to the test piece to complete the load loading.
[0023] The C-cavity accumulator 401, high-pressure accumulator 402, and low-pressure accumulator 403 are used to eliminate pressure fluctuations and replenish oil; the C-cavity pressure relief solenoid valve 501 and the A / B-cavity pressure relief solenoid valve 502 are used to unload the three-cavity hydraulic cylinder 100.
[0024] Specifically, the operation of the signal transmission components involves two servo valves: a C-chamber servo valve 601 and an A / B-chamber servo valve 602. Each servo valve has four ports: P, T, A, and B. Port P connects to the oil supply line, port T connects to the return line, and ports A and B connect to the actuator, a three-chamber hydraulic cylinder 100. These ports control the flow and pressure of the hydraulic oil in chambers A 103, B 102, and C 101 of the three-chamber hydraulic cylinder 100, causing the load from the load spectrum output by the three-chamber hydraulic cylinder 100 to act on the test piece, thus completing the load application. Filter 901 is used to filter the hydraulic oil at the inlet; the inlet 801 and outlet 802 are used to connect the hydraulic power source and the oil tank; the load sensor 301 is used to detect the load applied to the test piece in real time and feed back the detected load value to the A / B chamber servo valve 602 in real time; the differential pressure sensor 302 has two pressure sensing elements, which simultaneously detect the hydraulic pressure of chamber A 103 and chamber B 102, and output the hydraulic pressure difference between chamber A 103 and chamber B 102 for the feedback signal of chamber C servo valve 601.
[0025] like Figure 1-2 As shown in Example 1: A control method for a preloaded three-chamber hydraulic cylinder used in high- and low-cycle fatigue testing, comprising the following steps: The feedback data in the control closed loop of the three-chamber hydraulic cylinder 100C chamber 101 is collected, wherein the feedback data is the pressure data of the differential pressure sensor 302 of the three-chamber hydraulic cylinder 100A chamber 103 and B chamber 102; The feedback data in the control closed loop of the three-chamber hydraulic cylinder 100A chamber 103 and B chamber 102 is collected, wherein the feedback data is the load data of the load sensor 301; The control command 701 controlling the three-chamber hydraulic cylinder 100C chamber 101 is compared in real time with the pressure data of the differential pressure sensor 302 of the three-chamber hydraulic cylinder 100A chamber 103 and B chamber 102 to improve the control accuracy of the three-chamber cylinder high and low cycle fatigue test. The control command 702 for controlling chambers 103 (A chamber) and 102 (B chamber) of the three-chamber hydraulic cylinder 100 is compared in real time with the load data from the load sensor 301 to improve the control accuracy of the high- and low-cycle fatigue test of the three-chamber cylinder.
[0026] Example 2: The data of the control command 703 for controlling the load of the C chamber is compared with the feedback data in the control closed loop of the control of the three-chamber hydraulic cylinder 100C chamber 101. The feedback data is the pressure data of the three-chamber hydraulic cylinder 100C chamber 101. This improves the control accuracy of the high and low cycle fatigue test of the three-chamber cylinder.
[0027] In Example 1, the control method has two control loops. One loop controls the C chamber 101 of the three-chamber hydraulic cylinder 100, and the feedback is the pressure data from the differential pressure sensor 302 of the A chamber 103 and B chamber 102 of the three-chamber hydraulic cylinder 100, which is then compared with... Figure 7 The control command 701 is compared; the other is the control closed loop that controls chambers A 103 and B 102 of the three-chamber hydraulic cylinder 100, which feeds back the load data from the load sensor 301, and compares it with... Figure 6 The control commands in the second part, 702, are compared.
[0028] In Example 2, the control method controls the closed loop of the control of chamber C 101 of the three-chamber hydraulic cylinder 100. The feedback is the pressure data from the pressure sensor 303 of chamber C 101 of the three-chamber hydraulic cylinder 100, which is compared with control command 703. Control command 701 is as follows: Figure 8 As shown; another is the control closed loop that controls chambers A 103 and B 102 of the three-chamber hydraulic cylinder 100, which feeds back the load data from the load sensor 301, and... Figure 6 The control commands in the second part, 702, are compared.
Claims
1. A preloaded three-chamber hydraulic cylinder for high-low cycle fatigue testing, comprising a three-chamber hydraulic cylinder (100), a load sensor (301), a differential pressure sensor (302), a protection module valve group, characterized in that, The three-chamber hydraulic cylinder (100) includes chamber A (103), chamber B (102) and chamber C (101). The protection module valve group includes chamber C accumulator (401), high-pressure accumulator (402), low-pressure accumulator (403), chamber C pressure relief solenoid valve (501), chamber A / B pressure relief solenoid valve (502), chamber C servo valve (601), chamber A / B servo valve (602), oil inlet (801), oil outlet (802), filter (901) and valve body (1000). The oil inlet (801) is connected to the filter (901). The oil inlet (801) and the filter (901) are installed together on the valve body (1000). Inside the valve body (1000), the oil inlet is divided into two branches, which are respectively connected to the C-cavity servo valve (601) and the A / B-cavity servo valve (602). The C-cavity servo valve (601) and the A / B-cavity servo valve (602) are respectively connected to the three-cavity hydraulic cylinder (100) and are both connected to the oil outlet (801). 2); The C-cavity accumulator (401) is installed on the C-cavity (101) of the three-cavity hydraulic cylinder, the high-pressure accumulator (402) is installed on the oil inlet line, and the low-pressure accumulator (403) is installed on the oil return line; the C-cavity pressure relief solenoid valve (501) is installed between the C-cavity servo valve (601) and the three-cavity hydraulic cylinder (100), and the A / B-cavity pressure relief solenoid valve (502) is installed between the A-cavity (103) and the B-cavity (102); The load sensor (301) and the differential pressure sensor (302) are both installed on the three-chamber hydraulic cylinder (100). The load sensor (301) is used to measure the output force of the three-chamber hydraulic cylinder (100) and feed the measured force value back to the controller of the A / B chamber servo valve (602). The differential pressure sensor (302) outputs the hydraulic pressure difference between chamber A (103) and chamber B (102) and feeds the differential pressure data back to the controller of the C chamber servo valve (601).
2. A preloaded three chamber hydraulic cylinder for high and low cycle fatigue testing according to claim 1, characterized in that, The three-chamber hydraulic cylinder (100) also includes a built-in piston (108) and piston rod (109).
3. A preloaded three chamber hydraulic cylinder for high and low cycle fatigue testing according to claim 2, characterized in that, The working area of cavity A (103) and cavity B (102) is the annular area formed by piston (108) and piston rod (109), and the hydraulic parameters of cavity A (103) and cavity B (102) are symmetrical. C cavity (101) is a separate working cavity with a working area equal to the area of piston rod (109).
4. The preloaded three chamber hydraulic cylinder for high-low cycle fatigue testing of claim 3, wherein, The effective area of cavity C (101) is greater than that of cavity A (103) and cavity B (102).
5. The preloaded three chamber hydraulic cylinder for high-low cycle fatigue testing of claim 1, wherein, One end of the load sensor (301) is connected to the test piece (200) by a screw to detect the magnitude of the load applied to the test piece (200) in real time.
6. A preloaded three chamber hydraulic cylinder for high and low cycle fatigue testing according to claim 1, wherein, The C-cavity servo valve (601) and A / B-cavity servo valve (602) are used to control hydraulic oil. Each servo valve includes four oil ports: P, T, A, and B. Port P is connected to the oil supply line, port T is connected to the oil return line, and ports A and B are connected to the actuator, the three-cavity hydraulic cylinder (100). The valve is used to control the flow rate and pressure of hydraulic oil in the A-cavity (103), B-cavity (102), and C-cavity (101) of the three-cavity hydraulic cylinder (100), so that the load of the load spectrum output by the three-cavity hydraulic cylinder (100) acts on the test piece to complete the loading of the load.
7. A preloaded three-chamber hydraulic cylinder for high- and low-cycle fatigue testing according to claim 1, characterized in that, The C-cavity accumulator (401), high-pressure accumulator (402), and low-pressure accumulator (403) are used to eliminate pressure fluctuations and replenish oil; the C-cavity pressure relief solenoid valve (501) and the A / B-cavity pressure relief solenoid valve (502) are used to unload the three-cavity hydraulic cylinder (100).
8. A control method for a preloaded three-chamber hydraulic cylinder used in high- and low-cycle fatigue testing, characterized in that, The process, employing the preloaded three-chamber hydraulic cylinder used for high- and low-cycle fatigue testing as described in any one of claims 1 to 7, includes the following steps: (1) Collect feedback data in the control closed loop of the three-chamber hydraulic cylinder (100) C chamber (101), wherein the feedback data is the pressure data of the differential pressure sensor (302) of the three-chamber hydraulic cylinder (100) A chamber (103) and B chamber (102); (2) Collect feedback data in the control closed loop of the three-chamber hydraulic cylinder (100) A chamber (103) and B chamber (102), wherein the feedback data is the load data of the load sensor (301); (3) The data of the control command (701) controlling the C chamber (101) of the three-chamber hydraulic cylinder (100) is compared with the pressure data of the differential pressure sensor (302) of the A chamber (103) and B chamber (102) of the three-chamber hydraulic cylinder (100) in real time to improve the control accuracy of the high and low cycle fatigue test of the three-chamber cylinder; (4) The data of the control command 2 (702) controlling the A chamber (103) and B chamber (102) of the three-chamber hydraulic cylinder (100) is compared with the load data of the load sensor (301) in real time to improve the control accuracy of the high and low cycle fatigue test of the three-chamber cylinder.
9. A control method for a preloaded three-chamber hydraulic cylinder used in high- and low-cycle fatigue testing according to claim 8, characterized in that, The data of the control command three (703) controlling the load of the C cavity is compared with the feedback data in the control closed loop of the control of the three-cavity hydraulic cylinder (100) C cavity (101), wherein the feedback data is the pressure data of the three-cavity hydraulic cylinder (100) C cavity (101) in real time, so as to improve the control accuracy of the high and low cycle fatigue test of the three-cavity cylinder.