Hydraulic system for automatically testing stretching and retracting of oil cylinder and control method of hydraulic system

Abstract

The invention belongs to the technical field of hydraulic control, and particularly relates to an oil cylinder stretching automatic test hydraulic system and a control method thereof, and the oil cylinder stretching automatic test hydraulic system comprises an oil cylinder, first to fourth cartridge valves, first to fourth control valves, first and second pressure sensors and a laser displacement sensor. The system controls the on-off of the cartridge valve through the control valve group to drive the oil cylinder to stretch out and draw back; the pressure sensor and the displacement sensor are used for collecting pressure of two cavities of the oil cylinder and displacement data of the piston rod in real time. The control method is characterized in that the comparison module is used for comprehensively analyzing collected data and a preset threshold value, the stretching and retracting in-place state of the oil cylinder is accurately judged, and the valve piece is automatically controlled to act so as to complete reciprocating circulation. Meanwhile, the method can monitor abnormal pressure of the oil way in real time, and the machine is stopped immediately when faults such as pipe explosion occur. According to the invention, full-process automation and unattended operation of oil cylinder testing are realized, and high compatibility, high safety and high reliability are realized.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic control technology, and in particular relates to an automatic hydraulic system for testing the extension and retraction of a hydraulic cylinder and its control method. Background Technology

[0002] As the core actuator of a hydraulic system, the performance of the hydraulic cylinder directly determines the operational reliability, working accuracy, and safety stability of the entire machine. It is widely used in key fields such as engineering machinery, industrial automation, aerospace, metallurgy, and shipbuilding.

[0003] The hydraulic cylinder reciprocating durability test is an accelerated life test that simulates high-frequency reciprocating extension and retraction under actual working conditions. The test cycle is long, and manual operation can easily lead to fatigue and lack of concentration. The test pressure is high, and personnel or machinery may be injured due to pipeline rupture, poor welding quality of hydraulic cylinder, etc.

[0004] To ensure personnel safety, prevent personnel from being in dangerous areas for extended periods, and eliminate the risk of safety accidents at the source, it is necessary to test the automatic extension and retraction of the hydraulic cylinder.

[0005] The reciprocating durability test of hydraulic cylinders is achieved through automatic cylinder extension and retraction. Stroke-triggered methods cannot meet the testing requirements of hydraulic cylinders with different strokes, while time-triggered methods are compatible with different models and strokes of hydraulic cylinders, but the debugging cycle is long and the machine cannot be stopped in time if the hydraulic pipe ruptures. Traditional control methods cannot simultaneously achieve automatic cylinder extension and retraction and unattended testing functions.

[0006] Therefore, there is an urgent need for an automatic hydraulic system for testing cylinder extension and retraction and its control method. Summary of the Invention

[0007] The purpose of this invention is to provide an automatic hydraulic system for testing the extension and retraction of a hydraulic cylinder and its control method, so as to solve the above-mentioned problems.

[0008] To achieve the above objectives, the present invention provides the following solution:

[0009] An automatic hydraulic system for testing cylinder extension and retraction includes:

[0010] A hydraulic cylinder, comprising a piston rod, a rodless oil chamber, and a rod-type oil chamber;

[0011] It also includes a detection unit connected to the hydraulic cylinder, the detection unit being used to acquire movement data of the piston rod;

[0012] The movement data includes piston rod extension length data, rodless oil chamber oil pressure data, and rod-type oil chamber oil pressure data;

[0013] It also includes an oil inlet circuit, an oil return circuit, a first cartridge valve, a second cartridge valve, a third cartridge valve, and a fourth cartridge valve;

[0014] The oil inlet circuit is connected to one end of the first cartridge valve and the second cartridge valve;

[0015] The return oil circuit is connected to one end of the third cartridge valve and the fourth cartridge valve;

[0016] The other end of the first cartridge valve and the fourth cartridge valve are connected to the rodless oil chamber;

[0017] The other end of the second cartridge valve and the third cartridge valve are connected to the rod-mounted oil chamber;

[0018] When the piston rod is pushed out, the first cartridge valve and the third cartridge valve open, and the second cartridge valve and the fourth cartridge valve close. The hydraulic oil moves along the oil inlet circuit, the first cartridge valve, the rodless oil chamber, the rod oil chamber, the third cartridge valve, and the oil return circuit to form a connected oil circuit.

[0019] When the piston rod is reset, the first cartridge valve and the third cartridge valve are closed, and the second cartridge valve and the fourth cartridge valve are opened. The hydraulic oil moves along the oil inlet circuit, the second cartridge valve, the rod chamber, the rodless chamber, the fourth cartridge valve, and the oil return circuit to form a connected oil circuit.

[0020] It also includes a control module connected to the first cartridge valve, the second cartridge valve, the third cartridge valve and the fourth cartridge valve, and a comparison module connected to the control module. The comparison module is connected to the detection unit and is used to drive the control module to control the on / off state of the first cartridge valve, the second cartridge valve, the third cartridge valve and the fourth cartridge valve according to the movement data.

[0021] Optionally, the detection unit includes a first hydraulic pressure detection unit, a second hydraulic pressure detection unit, and a piston rod displacement detection unit. The first hydraulic pressure detection unit is connected to the rodless oil chamber, the second hydraulic pressure detection unit is connected to the rod oil chamber, and the piston rod displacement detection unit is located on one side of the piston rod.

[0022] The first hydraulic pressure detection unit, the second hydraulic pressure detection unit, and the piston rod displacement detection unit are connected to the comparison module.

[0023] Optionally, the control module includes a controller and a control oil circuit, the control oil circuit being connected to the first cartridge valve, the second cartridge valve, the third cartridge valve, and the fourth cartridge valve;

[0024] The controller is connected to the comparison module.

[0025] Optionally, the control oil circuit includes a first control valve, a second control valve, a third control valve, and a fourth control valve;

[0026] The first control valve is connected to the first cartridge valve, the second control valve is connected to the second cartridge valve, the third control valve is connected to the third cartridge valve, and the fourth control valve is connected to the fourth cartridge valve;

[0027] The first control valve, the second control valve, the third control valve, and the fourth control valve are connected to the controller;

[0028] It also includes controlling the oil inlet circuit and controlling the oil return circuit;

[0029] The control oil inlet circuit and the control oil return circuit are both connected to the first control valve, the second control valve, the third control valve and the fourth control valve.

[0030] Optionally, the controller is a PLC programmable controller.

[0031] Optionally, the first oil pressure detection unit is a first pressure sensor, which is connected to the rodless oil chamber and the comparison module. The first pressure sensor is used to acquire oil pressure data of the rodless oil chamber.

[0032] Optionally, the second oil pressure detection unit is a second pressure sensor, which is connected to the rod oil chamber and the comparison module. The second pressure sensor is used to acquire the oil pressure data of the rod oil chamber.

[0033] Optionally, the piston rod displacement detection unit is a laser displacement sensor, which is located on one side of the piston rod and connected to the comparison module. The laser displacement sensor is used to acquire the extension length data of the piston rod.

[0034] A control method for an automatic hydraulic system for testing cylinder extension and retraction, using the aforementioned automatic hydraulic system for testing cylinder extension and retraction, includes the following steps:

[0035] The comparison module presets the number of extension / retraction cycles, preset extension movement data, and reset movement data.

[0036] When the piston rod extends, the control module opens the first cartridge valve and the third cartridge valve, while keeping the second cartridge valve and the fourth cartridge valve closed.

[0037] The detection unit acquires the movement data;

[0038] During the process of the piston rod moving to the end, the comparison module compares the movement data with the extension movement data. When the movement data matches the extension movement data, it is determined that the extension is in place. Then, the comparison module sends a signal to the control module, and the control module closes the first cartridge valve and the third cartridge valve, and the ejection process ends.

[0039] When the piston rod is reset, the control module opens the second cartridge valve and the fourth cartridge valve, while keeping the first cartridge valve and the third cartridge valve closed.

[0040] The detection unit acquires the movement data;

[0041] During the piston rod reset process, the comparison module compares the movement data with the reset movement data. When the movement data matches the reset movement data, it is determined that the reset is in place. Subsequently, the comparison module sends a signal to the control module, which then closes the second cartridge valve and the fourth cartridge valve, and the reset process ends.

[0042] Optionally, the extension movement data and the reset movement data both include the extreme values ​​of the oil pressure in the rod chamber, the extreme values ​​of the oil pressure in the rodless chamber, and the extreme values ​​of the piston rod extension length;

[0043] The comparison module obtains a first difference between the extreme value of the rod oil chamber pressure and the oil pressure data of the rod oil chamber, a second difference between the extreme value of the rodless oil chamber pressure and the oil pressure data of the rodless oil chamber, and a third difference between the extreme value of the piston rod extension length and the piston rod extension length data.

[0044] During the extension of the piston rod, when the first difference is equal to the extreme value of the oil pressure in the rod oil chamber, and the second difference is zero and the third difference is zero, the piston rod reaches the extension limit, and the comparison module sends a signal to the controller to close the first cartridge valve and the third cartridge valve and open the second cartridge valve and the fourth cartridge valve.

[0045] During the piston rod reset process, when the first difference is zero, and the second difference is equal to the extreme value of the oil pressure in the rodless oil chamber, and the third difference is equal to the extreme value of the piston rod extension length, the comparison module sends a signal to the controller to open the first cartridge valve, the third cartridge valve, and close the second cartridge valve and the fourth cartridge valve.

[0046] When the oil pressure data of the rod-side oil chamber or the oil pressure data of the rodless oil chamber obtained by the detection unit is continuously zero, and the third difference does not change, the comparison module sends a signal to the controller to close the first cartridge valve, the second cartridge valve, the third cartridge valve and the fourth cartridge valve.

[0047] Compared with the prior art, the present invention has the following advantages and technical effects:

[0048] This system achieves full automation of the hydraulic cylinder extension and retraction process through the collaboration of the control and comparison modules. It enables unattended automated testing, using multi-sensor data fusion to determine the positioning status, replacing traditional triggering methods that rely on fixed strokes or times, significantly improving the intelligence and reliability of the testing. Furthermore, the system possesses powerful fault monitoring capabilities. When anomalies such as hydraulic pipe rupture occur, the movement data acquired by the detection unit will show abnormalities. The comparison module quickly identifies these anomalies and commands a shutdown, effectively preventing equipment damage and ensuring safety, eliminating the risk of safety accidents during the testing process at its source. In addition, the system has strong compatibility, adapting to the testing needs of different models and stroke hydraulic cylinders, greatly shortening the debugging cycle and improving testing efficiency. It is particularly suitable for long-term, high-frequency reciprocating durability testing of hydraulic cylinders in fields such as engineering machinery and industrial automation. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0050] Figure 1 This is a hydraulic schematic diagram illustrating the automatic extension and retraction of the oil cylinder according to the present invention.

[0051] Figure 2 This is a schematic diagram illustrating the process of achieving automatic extension and retraction of the hydraulic cylinder according to the present invention;

[0052] Figure 3 This is a schematic diagram of the data acquisition trajectory of the hydraulic cylinder extension according to the present invention;

[0053] Figure 4 This is a schematic diagram of the data trajectory collected during the retraction of the hydraulic cylinder according to the present invention;

[0054] Among them, 1. First control valve; 2. Second control valve; 3. Third control valve; 4. Fourth control valve; 5. First cartridge valve; 6. Second cartridge valve; 7. Third cartridge valve; 8. Fourth cartridge valve; 9. First pressure sensor; 10. Second pressure sensor; 11. Laser displacement sensor; 12. Hydraulic cylinder. Detailed Implementation

[0055] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0057] Reference Figures 1 to 4 This invention discloses an automatic hydraulic system for testing the extension and retraction of a hydraulic cylinder, comprising:

[0058] Hydraulic cylinder 12 includes a piston rod, a rodless oil chamber, and a rod-type oil chamber;

[0059] It also includes a detection unit, which is connected to the hydraulic cylinder 12, and the detection unit is used to acquire the movement data of the piston rod;

[0060] The movement data includes piston rod extension length data, rodless oil chamber oil pressure data, and rod oil chamber oil pressure data;

[0061] It also includes an oil inlet circuit, an oil return circuit, a first cartridge valve 5, a second cartridge valve 6, a third cartridge valve 7, and a fourth cartridge valve 8;

[0062] The oil inlet circuit is connected to one end of the first cartridge valve 5 and the second cartridge valve 6;

[0063] The return oil circuit is connected to one end of the third cartridge valve 7 and the fourth cartridge valve 8;

[0064] The other ends of the first cartridge valve 5 and the fourth cartridge valve 8 are connected to the rodless oil chamber;

[0065] The other ends of the second cartridge valve 6 and the third cartridge valve 7 are connected to the rod-mounted oil chamber;

[0066] When the piston rod is pushed out, the first cartridge valve 5 and the third cartridge valve 7 are opened, and the second cartridge valve 6 and the fourth cartridge valve 8 are closed. The hydraulic oil moves along the oil inlet circuit, the first cartridge valve 5, the rodless oil chamber, the rod oil chamber, the third cartridge valve 7, and the oil return circuit to form a connected oil circuit.

[0067] When the piston rod is reset, the first cartridge valve 5 and the third cartridge valve 7 are closed, and the second cartridge valve 6 and the fourth cartridge valve 8 are opened. The hydraulic oil moves along the oil inlet circuit, the second cartridge valve 6, the rod chamber, the rodless chamber, the fourth cartridge valve 8, and the oil return circuit to form a connected oil circuit.

[0068] It also includes a control module connected to the first cartridge valve 5, the second cartridge valve 6, the third cartridge valve 7 and the fourth cartridge valve 8, and a comparison module connected to the control module. The comparison module is connected to the detection unit and is used to drive the control module to control the opening and closing of the first cartridge valve 5, the second cartridge valve 6, the third cartridge valve 7 and the fourth cartridge valve 8 according to the movement data.

[0069] When the piston rod needs to extend, the control module opens the first cartridge valve 5 and the third cartridge valve 7, while keeping the second cartridge valve 6 and the fourth cartridge valve 8 closed. At this time, hydraulic oil enters the rodless chamber of the cylinder 12 from the inlet oil passage through the opened first cartridge valve 5, pushing the piston rod out. Simultaneously, the oil in the rod chamber is pushed by the piston and discharged into the return oil passage through the opened third cartridge valve 7, forming a complete ejection circulation circuit. During this process, the detection unit continuously acquires the piston rod's movement data, which is transmitted to the comparison module. When the piston rod reaches its end, the comparison module identifies that the piston rod has reached the set extension movement data, thus determining that it has reached the extension position. The comparison module then sends a signal to the control module, which closes the first cartridge valve 5 and the third cartridge valve 7, ending the ejection process.

[0070] Conversely, when piston rod reset is required, the control module changes the control logic, opening the second cartridge valve 6 and the fourth cartridge valve 8 while keeping the first cartridge valve 5 and the third cartridge valve 7 closed. Hydraulic oil enters the rod chamber of cylinder 12 from the inlet oil line through the opened second cartridge valve 6, pushing the piston rod to retract; the oil in the rodless oil chamber is discharged into the return oil line through the opened fourth cartridge valve 8. The detection unit also continuously monitors, and the comparison module analyzes the data. When it identifies that the piston rod has reached the set retraction movement data, it determines that it has retracted to the correct position and instructs the control module to close the corresponding cartridge valve.

[0071] This system achieves full automation of the extension and retraction process of hydraulic cylinder 12 through the collaboration of the control and comparison modules. It enables unattended automated testing, using multi-sensor data fusion to determine the positioning status, replacing the traditional triggering method that relies on fixed strokes or times, significantly improving the intelligence and reliability of the test. Furthermore, the system possesses powerful fault monitoring capabilities. When anomalies such as hydraulic pipe rupture occur, the movement data acquired by the detection unit will show abnormalities. The comparison module quickly identifies these anomalies and commands a shutdown, effectively preventing equipment damage and ensuring safety, eliminating the risk of safety accidents during the testing process at its source. In addition, the system has strong compatibility, adapting to the testing needs of different models and stroke hydraulic cylinders, greatly shortening the debugging cycle and improving testing efficiency. It is particularly suitable for long-term, high-frequency reciprocating durability testing of hydraulic cylinders in fields such as engineering machinery and industrial automation.

[0072] As an optional implementation, the detection unit includes a first hydraulic pressure detection unit, a second hydraulic pressure detection unit, and a piston rod displacement detection unit. The first hydraulic pressure detection unit is connected to the rodless oil chamber, the second hydraulic pressure detection unit is connected to the rod oil chamber, and the piston rod displacement detection unit is located on one side of the piston rod.

[0073] The first hydraulic pressure detection unit, the second hydraulic pressure detection unit, and the piston rod displacement detection unit are connected to the comparison module.

[0074] During the automatic testing of hydraulic cylinder 12, the first hydraulic pressure detection unit monitors the pressure in the rodless oil chamber in real time, the second hydraulic pressure detection unit monitors the pressure in the rod oil chamber, and the piston rod displacement detection unit detects the piston rod position. All three units transmit the data to the comparison module in real time. By comprehensively judging the pressure threshold, pressure change rate, and displacement extreme value, the module precisely controls the hydraulic cylinder to extend and retract to its designated position and automatically monitors for faults such as pipe rupture, ensuring the safety and automation of the testing process.

[0075] As an optional implementation, the control module includes a controller and a control oil circuit, the control oil circuit being connected to the first cartridge valve 5, the second cartridge valve 6, the third cartridge valve 7 and the fourth cartridge valve 8;

[0076] The controller is connected to the comparator module.

[0077] As an optional implementation, the control oil circuit includes a first control valve 1, a second control valve 2, a third control valve 3, and a fourth control valve 4;

[0078] The first control valve 1 is connected to the first cartridge valve 5, the second control valve 2 is connected to the second cartridge valve 6, the third control valve 3 is connected to the third cartridge valve 7, and the fourth control valve 4 is connected to the fourth cartridge valve 8.

[0079] The first control valve 1, the second control valve 2, the third control valve 3 and the fourth control valve 4 are connected to the controller;

[0080] It also includes controlling the oil inlet circuit and controlling the oil return circuit;

[0081] The control oil inlet circuit and the control oil return circuit are both connected to the first control valve 1, the second control valve 2, the third control valve 3 and the fourth control valve 4.

[0082] During the automatic testing of cylinder 12, the controller, according to the instructions of the comparison module, precisely manipulates the opening and closing of the first cartridge valve 5, the second cartridge valve 6, the third cartridge valve 7, and the fourth cartridge valve 8 on the main oil circuit by controlling the energization and de-energization of the electromagnets of the first control valve 1, the second control valve 2, the third control valve 3, and the fourth control valve 4. Specifically, the control oil inlet circuit provides stable pilot pressure oil to the P port of all control valves; the control oil return circuit is connected to the T port of each control valve, forming the return path of the pilot oil.

[0083] When the cylinder needs to extend, the controller energizes the solenoids of the first control valve 1 and the third control valve 3. Pilot pressure oil then flows from the pilot control chambers of the first cartridge valve 5 and the third cartridge valve 7 back to the return port T via port A. The pressure in the pilot control chambers of the first cartridge valve 5 and the third cartridge valve 7 is zero, and the cartridge valve cores open, thus connecting the main oil circuit. When the cylinder retracts, the second control valve 2 and the fourth control valve 4 execute the same control logic. After the action is completed, the controller de-energizes the solenoids, the control valves reset, and pilot pressure oil enters the pilot control chamber through the control inlet circuit. The main cartridge valve closes smoothly under hydraulic pressure, effectively reducing hydraulic shock.

[0084] As an optional implementation, the controller is a PLC programmable controller.

[0085] As an optional implementation, the first oil pressure detection unit is a first pressure sensor 9, which is connected to the rodless oil chamber and to a comparison module. The first pressure sensor 9 is used to acquire oil pressure data of the rodless oil chamber.

[0086] As an optional implementation, the second oil pressure detection unit is a second pressure sensor 10, which is connected to the rod oil chamber and to a comparison module. The second pressure sensor 10 is used to acquire oil pressure data of the rod oil chamber.

[0087] As an optional implementation, the piston rod displacement detection unit is a laser displacement sensor 11. The laser displacement sensor 11 is located on one side of the piston rod and is connected to the comparison module. The laser displacement sensor 11 is used to acquire piston rod extension length data.

[0088] The specific connection method of the present invention is as follows:

[0089] This system includes a first control valve 1, a second control valve 2, a third control valve 3, a fourth control valve 4, a first cartridge valve 5, a second cartridge valve 6, a third cartridge valve 7, a fourth cartridge valve 8, a first pressure sensor 9, a second pressure sensor 10, a laser displacement sensor 11, and a hydraulic cylinder 12.

[0090] The first cartridge valve 5, the second cartridge valve 6, the third cartridge valve 7, the fourth cartridge valve 8, the first pressure sensor 9, and the second pressure sensor 10 form a valve group 1.

[0091] In valve assembly one, the lower sides of the first cartridge valve 5 and the second cartridge valve 6 are connected to the system pressure oil port;

[0092] The lower sides of the third cartridge valve 7 and the fourth cartridge valve 8 in valve group one are connected to the system return port;

[0093] In valve group one, the annular oil port of the first cartridge valve 5 and the fourth cartridge valve 8, and the first pressure sensor 9 are connected to the rodless chamber of the oil cylinder 12.

[0094] In valve group one, the annular oil ports of the second cartridge valve 6 and the third cartridge valve 7, the second pressure sensor 10, and the rod chamber of the oil cylinder 12 are connected and communicate with each other.

[0095] The first control valve 1 and the second control valve 2 form valve group two, and the third control valve 3 and the fourth control valve 4 form valve group three.

[0096] The P port of valve group 2 is connected to the pilot pressure oil, and the T port of valve group 2 is connected to the pilot return oil.

[0097] The pilot ports of the first cartridge valve 5 and the second cartridge valve 6 in valve group one are connected to the A ports of the first control valve 1 and the second control valve 2 in valve group two.

[0098] Similarly, the P port of valve assembly 3 is connected to the pilot pressure oil, and the T port of valve assembly 3 is connected to the pilot return oil.

[0099] The pilot ports of the third cartridge valve 7 and the fourth cartridge valve 8 in valve group one are connected to the A ports of the third control valve 3 and the fourth control valve 4 in valve group three.

[0100] The extension and retraction detection of hydraulic cylinder 12 is equipped with a laser displacement sensor 11.

[0101] A control method for an automatic hydraulic system for testing cylinder extension and retraction, using the aforementioned automatic hydraulic system for testing cylinder extension and retraction, includes the following steps:

[0102] Within the comparison module, preset the number of extension / retraction cycles, preset the extension movement data, and reset the movement data;

[0103] When the piston rod extends, the control module opens the first cartridge valve 5 and the third cartridge valve 7, while keeping the second cartridge valve 6 and the fourth cartridge valve 8 closed.

[0104] The detection department acquires movement data;

[0105] During the piston rod's movement to the end, the comparison module compares the movement data with the extension movement data. When the movement data matches the extension movement data, it is determined that the extension is complete. Subsequently, the comparison module sends a signal to the control module, which then closes the first cartridge valve 5 and the third cartridge valve 7, ending the ejection process.

[0106] When the piston rod is reset, the control module opens the second cartridge valve 6 and the fourth cartridge valve 8, while keeping the first cartridge valve 5 and the third cartridge valve 7 closed.

[0107] The detection department acquires movement data;

[0108] During the piston rod reset process, the comparison module compares the movement data with the reset movement data. When the movement data matches the reset movement data, it is determined that the reset is in place. Then, the comparison module sends a signal to the control module, which closes the second cartridge valve 6 and the fourth cartridge valve 8, and the reset process ends.

[0109] The core of this control method lies in achieving fully automatic testing of the hydraulic cylinder 12 through closed-loop control of preset data and real-time monitoring. Its operation begins by presetting the number of extension / retraction cycles, preset extension movement data, and reset movement data within the comparison module. These data include the threshold combinations monitored by the first hydraulic pressure detection unit, the second hydraulic pressure detection unit, and the piston rod displacement detection unit, as well as the number of extension / retraction cycles.

[0110] Upon receiving the piston rod extension command, the control module first opens the first cartridge valve 5 and the third cartridge valve 7, while ensuring that the second cartridge valve 6 and the fourth cartridge valve 8 are closed. Hydraulic oil then drives the cylinder 12 to extend. During this process, the detection unit continuously acquires real-time movement data and transmits it to the comparison module. The comparison module compares the real-time data with preset extension movement data. When all three conditions are met simultaneously—the pressure in the rodless chamber rising to a threshold and stabilizing, the pressure in the rod chamber dropping to near zero and stabilizing, and the displacement reaching its maximum value—the extension is considered complete. Subsequently, the comparison module sends a signal to the control module, which immediately closes the first cartridge valve 5 and the third cartridge valve 7, smoothly concluding the ejection process.

[0111] The piston rod reset process is symmetrical and similar: the control module switches to open the second cartridge valve 6 and the fourth cartridge valve 8, while keeping the first cartridge valve 5 and the third cartridge valve 7 closed. The comparison module continuously compares the real-time movement data returned by the detection unit with the preset reset movement data. When the rod chamber pressure rises to the threshold and stabilizes, the rodless chamber pressure drops to near zero and stabilizes, and the displacement reaches the minimum value, it is determined that the reset is in place, and the control module is instructed to close the second cartridge valve 6 and the fourth cartridge valve 8.

[0112] This method achieves extremely high accuracy and reliability in position detection through multi-parameter fusion judgment, completely overcoming the limitations of traditional stroke or time-triggered methods. The system possesses intelligent fault diagnosis capabilities; if a hydraulic pipe ruptures, causing abnormal pressure or displacement data, it can immediately and automatically shut down, ensuring absolute safety during unattended testing. Furthermore, this method has inherent compatibility with hydraulic cylinders 12 of different models and strokes; only the corresponding data thresholds need to be preset, without requiring hardware modifications, greatly simplifying the debugging process and improving testing efficiency. It is an ideal solution for achieving long-term, high-frequency, automated reciprocating durability testing.

[0113] As an optional implementation, both the extension movement data and the reset movement data include the extreme values ​​of the oil pressure in the rod chamber, the extreme values ​​of the oil pressure in the rodless chamber, and the extreme values ​​of the piston rod extension length.

[0114] The comparison module obtains the first difference between the extreme value of the rod oil chamber pressure and the oil pressure data of the rod oil chamber, the second difference between the extreme value of the rodless oil chamber pressure and the oil pressure data of the rodless oil chamber, and the third difference between the extreme value of the piston rod extension length and the piston rod extension length data.

[0115] During the piston rod extension process, when the first difference is equal to the extreme value of the oil pressure in the rod oil chamber, and the second difference is zero and the third difference is zero, the piston rod reaches the extension limit, and the comparison module sends a signal to the controller to close the first cartridge valve 5 and the third cartridge valve 7 and open the second cartridge valve 6 and the fourth cartridge valve 8.

[0116] During the piston rod reset process, when the first difference is zero, the second difference is equal to the extreme value of the oil pressure in the rodless oil chamber, and the third difference is equal to the extreme value of the piston rod extension length, the comparison module sends a signal to the controller to open the first cartridge valve 5, the third cartridge valve 7, and close the second cartridge valve 6 and the fourth cartridge valve 8.

[0117] When the oil pressure data of the rod-side oil chamber or the rodless oil chamber obtained by the detection unit is continuously zero, the comparison module sends a signal to the controller to close the first cartridge valve 5, the second cartridge valve 6, the third cartridge valve 7 and the fourth cartridge valve 8.

[0118] The comparison module's preset extension and reset movement data includes the extreme values ​​of the rod chamber oil pressure, the rodless chamber oil pressure, and the piston rod extension length. During piston rod extension, the comparison module continuously calculates the differences between the real-time collected rod chamber oil pressure data, rodless chamber oil pressure data, and piston rod extension length data and the corresponding preset extreme values. When the calculated first difference equals the rod chamber oil pressure extreme value, the second difference is zero, and the third difference is zero, the piston rod is determined to be fully extended. The comparison module then sends a signal to the controller, which closes the first cartridge valve 5 and the third cartridge valve 7 to prepare for subsequent actions. The judgment conditions for the piston rod reset process are symmetrical: when the first difference is zero, the second difference equals the rodless chamber oil pressure extreme value, and the third difference equals the piston rod extension length extreme value, the reset is determined to be complete, and the controller then operates the corresponding cartridge valve. Crucially, this method integrates a powerful fault monitoring function: if the oil pressure data of the rod-side oil chamber or the rodless oil chamber obtained by the detection unit remains zero, it indicates a serious oil circuit leak or pipe rupture. The comparison module will immediately instruct the controller to close all cartridge valves, and the system will shut down in an emergency.

[0119] The technical benefits of this method are remarkable. Through rigorous differential logic, it elevates the reliability of position detection to a new level, ensuring precise and error-free action transitions. More importantly, it deeply integrates automatic control with proactive safety protection, achieving truly intelligent unattended testing. The system can not only automatically complete reciprocating cycles but also respond instantly to fault signs such as abnormal oil pressure loss, automatically locking the oil circuit. This fundamentally eliminates the risk of equipment damage or safety hazards caused by accidents such as oil pipe ruptures, greatly improving the safety and automation level of the entire testing system.

[0120] The control method for the hydraulic circuit that enables the automatic extension and retraction of cylinder 12 includes the following steps:

[0121] Step 1: Before the hydraulic cylinder 12 is activated, the control signals of the first control valve 1, the second control valve 2, the third control valve 3, and the fourth control valve 4 are all 0, the electromagnet is de-energized, and under the action of the pilot pressure oil, the first cartridge valve 5, the second cartridge valve 6, the third cartridge valve 7, and the fourth cartridge valve 8 are closed.

[0122] Step 2: The first control valve 1 and the third control valve 3 receive control signals, the electromagnet is energized, the first cartridge valve 5 and the third cartridge valve 7 open, and the hydraulic cylinder 12 extends. The first pressure sensor 9 collects the pressure in the rodless chamber of the hydraulic cylinder 12, the second pressure sensor 10 collects the pressure in the rod chamber of the hydraulic cylinder 12, and the laser displacement sensor 11 collects the displacement of the hydraulic cylinder 12.

[0123] Step 3: When the hydraulic cylinder 12 extends to its full position, the pressure of the first pressure sensor 9 increases to the full position threshold and the pressure value remains unchanged with respect to time. The pressure of the second pressure sensor 10 decreases to the full position threshold and the pressure value remains unchanged with respect to time. At this time, the laser displacement sensor 11 is at its maximum stroke value. When all three conditions are met simultaneously, it proves that the hydraulic cylinder 12 has extended to its full position.

[0124] Step 4: The system pressure decreases, reducing the pressure impact during shutdown. The control signals of the first control valve 1 and the third control valve 3 are 0, the electromagnet is de-energized, and the first cartridge valve 5 and the third cartridge valve 7 are closed under the action of the pilot pressure oil.

[0125] Step 5: The second control valve 2 and the fourth control valve 4 receive control signals, the electromagnet is energized, the second cartridge valve 6 and the fourth cartridge valve 8 open, and the hydraulic cylinder 12 retracts. The first pressure sensor 9 collects the pressure in the rodless chamber of the hydraulic cylinder 12, the second pressure sensor 10 collects the pressure in the rod chamber of the hydraulic cylinder 12, and the laser displacement sensor collects the displacement of the hydraulic cylinder 12.

[0126] Step Six: When the hydraulic cylinder 12 retracts to its position, the pressure of the second pressure sensor 10 increases to the position threshold and the pressure value remains basically unchanged when differentiated with respect to time. The pressure of the first pressure sensor 9 decreases to the position threshold and the pressure value remains basically unchanged when differentiated with respect to time. At this time, the laser displacement sensor 11 is at its minimum stroke. When all three conditions are met, it proves that the hydraulic cylinder 12 has retracted to its position.

[0127] Step 7: The system pressure decreases, reducing the pressure impact during shutdown. The control signals of the second control valve 2 and the fourth control valve 4 are 0, the electromagnet is de-energized, and the second cartridge valve 6 and the fourth cartridge valve 8 are closed under the action of the pilot pressure oil.

[0128] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0129] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A hydraulic system for automatically testing the extension and retraction of a hydraulic cylinder, characterized in that, include: The hydraulic cylinder (12) includes a piston rod, a rodless oil chamber, and a rod-type oil chamber; It also includes a detection unit connected to the oil cylinder (12), the detection unit being used to acquire the movement data of the piston rod; The movement data includes piston rod extension length data, rodless oil chamber oil pressure data, and rod-type oil chamber oil pressure data; It also includes an oil inlet circuit, an oil return circuit, a first cartridge valve (5), a second cartridge valve (6), a third cartridge valve (7), and a fourth cartridge valve (8); The oil inlet circuit is connected to one end of the first cartridge valve (5) and the second cartridge valve (6); The return oil circuit is connected to one end of the third cartridge valve (7) and the fourth cartridge valve (8); The other end of the first cartridge valve (5) and the fourth cartridge valve (8) are connected to the rodless oil chamber; The other end of the second cartridge valve (6) and the third cartridge valve (7) are connected to the rod oil chamber; When the piston rod is pushed out, the first cartridge valve (5) and the third cartridge valve (7) are opened, and the second cartridge valve (6) and the fourth cartridge valve (8) are closed. The hydraulic oil moves along the oil inlet path, the first cartridge valve (5), the rodless oil chamber, the rod oil chamber, the third cartridge valve (7), and the oil return path to form a connected oil passage. When the piston rod is reset, the first cartridge valve (5) and the third cartridge valve (7) are closed, and the second cartridge valve (6) and the fourth cartridge valve (8) are opened. The hydraulic oil moves along the oil inlet path, the second cartridge valve (6), the rod oil chamber, the rodless oil chamber, the fourth cartridge valve (8), and the oil return path to form a connected oil passage. It also includes a control module connected to the first cartridge valve (5), the second cartridge valve (6), the third cartridge valve (7) and the fourth cartridge valve (8) and a comparison module connected to the control module. The comparison module is connected to the detection unit and is used to drive the control module to control the opening and closing of the first cartridge valve (5), the second cartridge valve (6), the third cartridge valve (7) and the fourth cartridge valve (8) according to the movement data.

2. The hydraulic system for automatic testing of cylinder extension and retraction according to claim 1, characterized in that: The detection unit includes a first hydraulic pressure detection unit, a second hydraulic pressure detection unit, and a piston rod displacement detection unit. The first hydraulic pressure detection unit is connected to the rodless oil chamber, the second hydraulic pressure detection unit is connected to the rod oil chamber, and the piston rod displacement detection unit is located on one side of the piston rod. The first hydraulic pressure detection unit, the second hydraulic pressure detection unit, and the piston rod displacement detection unit are connected to the comparison module.

3. The hydraulic system for automatic testing of cylinder extension and retraction according to claim 1, characterized in that: The control module includes a controller and a control oil circuit, which is connected to the first cartridge valve (5), the second cartridge valve (6), the third cartridge valve (7), and the fourth cartridge valve (8). The controller is connected to the comparison module.

4. The hydraulic system for automatic testing of cylinder extension and retraction according to claim 3, characterized in that: The control oil circuit includes a first control valve (1), a second control valve (2), a third control valve (3), and a fourth control valve (4). The first control valve (1) is connected to the first cartridge valve (5), the second control valve (2) is connected to the second cartridge valve (6), the third control valve (3) is connected to the third cartridge valve (7), and the fourth control valve (4) is connected to the fourth cartridge valve (8). The first control valve (1), the second control valve (2), the third control valve (3) and the fourth control valve (4) are connected to the controller; It also includes controlling the oil inlet circuit and controlling the oil return circuit; The control oil inlet circuit and the control oil return circuit are both connected to the first control valve (1), the second control valve (2), the third control valve (3) and the fourth control valve (4).

5. The hydraulic system for automatic testing of cylinder extension and retraction according to claim 3, characterized in that: The controller is a PLC programmable controller.

6. The hydraulic system for automatic testing of cylinder extension and retraction according to claim 2, characterized in that: The first oil pressure detection unit is a first pressure sensor (9), which is connected to the rodless oil chamber and is connected to the comparison module. The first pressure sensor (9) is used to acquire oil pressure data of the rodless oil chamber.

7. The hydraulic system for automatic testing of cylinder extension and retraction according to claim 6, characterized in that: The second oil pressure detection unit is a second pressure sensor (10). The second pressure sensor (10) is connected to the rod oil chamber and is connected to the comparison module. The second pressure sensor (10) is used to acquire the oil pressure data of the rod oil chamber.

8. The hydraulic system for automatic testing of cylinder extension and retraction according to claim 7, characterized in that: The piston rod displacement detection unit is a laser displacement sensor (11). The laser displacement sensor (11) is located on one side of the piston rod and is connected to the comparison module. The laser displacement sensor (11) is used to acquire the extension length data of the piston rod.

9. A control method for an automatic hydraulic system for testing the extension and retraction of a hydraulic cylinder, using the automatic hydraulic system for testing the extension and retraction of a hydraulic cylinder as described in any one of claims 1-8, characterized in that, Includes the following steps: The comparison module presets the number of extension / retraction cycles, preset extension movement data, and reset movement data. When the piston rod extends, the control module opens the first cartridge valve (5) and the third cartridge valve (7), while keeping the second cartridge valve (6) and the fourth cartridge valve (8) closed. The detection unit acquires the movement data; During the process of the piston rod moving to the end, the comparison module compares the movement data with the extension movement data. When the movement data matches the extension movement data, it is determined that the extension is in place. Then the comparison module sends a signal to the control module, and the control module closes the first cartridge valve (5) and the third cartridge valve (7), and the ejection process ends. When the piston rod is reset, the control module opens the second cartridge valve (6) and the fourth cartridge valve (8), while keeping the first cartridge valve (5) and the third cartridge valve (7) closed. The detection unit acquires the movement data; During the piston rod reset process, the comparison module compares the movement data with the reset movement data. When the movement data matches the reset movement data, it is determined that the reset is in place. Then, the comparison module sends a signal to the control module, and the control module closes the second cartridge valve (6) and the fourth cartridge valve (8), and the reset process ends.

10. The control method for an automatic testing hydraulic system for cylinder extension and retraction according to claim 9, characterized in that: Both the extension movement data and the reset movement data include the extreme values ​​of the oil pressure in the rod chamber, the extreme values ​​of the oil pressure in the rodless chamber, and the extreme values ​​of the piston rod extension length. The comparison module obtains a first difference between the extreme value of the rod oil chamber pressure and the oil pressure data of the rod oil chamber, a second difference between the extreme value of the rodless oil chamber pressure and the oil pressure data of the rodless oil chamber, and a third difference between the extreme value of the piston rod extension length and the piston rod extension length data. During the extension of the piston rod, when the first difference is equal to the extreme value of the oil pressure in the rod oil chamber, and the second difference is zero and the third difference is zero, the piston rod reaches the extension limit, and the comparison module sends a signal to the controller to close the first cartridge valve (5), the third cartridge valve (7), and open the second cartridge valve (6) and the fourth cartridge valve (8); During the piston rod reset process, when the first difference is zero, and the second difference is equal to the extreme value of the oil pressure in the rodless oil chamber, and the third difference is equal to the extreme value of the piston rod extension length, the comparison module sends a signal to the controller to open the first cartridge valve (5), the third cartridge valve (7), and close the second cartridge valve (6) and the fourth cartridge valve (8). When the oil pressure data of the rod-side oil chamber or the oil pressure data of the rodless oil chamber obtained by the detection unit is continuously zero and the third difference does not change, the comparison module sends a signal to the controller to close the first cartridge valve (5), the second cartridge valve (6), the third cartridge valve (7) and the fourth cartridge valve (8).

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