Control system for a hydraulic cylinder

Abstract

The control system of the hydraulic cylinder provided by the present disclosure belongs to the technical field of hydraulic control. The control system comprises a pump group, two control valve groups, a detection assembly and an electric control assembly. The pump group is connected with the oil inlet of the two control valve groups. The two control valve groups correspond to two hydraulic cylinders one by one. Each control valve group in the two control valve groups is connected with the rod cavity and the rodless cavity of the corresponding hydraulic cylinder. The detection assembly is connected with the piston rod of the two hydraulic cylinders respectively. The detection assembly is configured to detect the load force and displacement of the piston rod in the two hydraulic cylinders. The electric control assembly is electrically connected with the detection assembly and the two control valve groups respectively. The present disclosure can improve the precision of synchronous action of the hydraulic cylinder.

Description

Technical Field

[0001] This disclosure belongs to the field of hydraulic control technology, and specifically relates to a control system for a hydraulic cylinder. Background Technology

[0002] In the field of lifting, it is common to encounter lifting devices that are connected to at least two hydraulic cylinders simultaneously. By controlling the synchronous movement of at least two hydraulic cylinders, the lifting device can be kept horizontal during movement.

[0003] In related technologies, when controlling the synchronous movement of at least two hydraulic cylinders, a mechanical passive synchronization method is generally adopted. This involves rigidly connecting the cylinder bodies and piston rods of at least two hydraulic cylinders via a mechanical structure, and interconnecting the rodless chambers and rod chambers of at least two hydraulic cylinders, ensuring that the working pressure and output force of each cylinder are identical. To improve control precision, the at least two hydraulic cylinders are arranged in a row with even spacing. A hydraulic control system then controls these at least two hydraulic cylinders. The hydraulic control system includes a pump assembly and a control valve assembly. The control valve assembly allows the high-pressure oil output from the pump assembly to enter the rodless or rod chamber of each hydraulic cylinder through pipelines.

[0004] However, under certain operating conditions, these hydraulic cylinders are spaced far apart, and the load is an offset load. Because the piston rods of each hydraulic cylinder are rigidly connected, the theoretical force and working pressure of each cylinder differ significantly, with cylinders closer to the load's center of gravity experiencing higher working pressures. Therefore, directly connecting the cylinders through pipelines clearly cannot achieve synchronization by ensuring that the piston rod displacements of each cylinder are identical. Summary of the Invention

[0005] This disclosure provides a control system for a hydraulic cylinder capable of lifting an offset load. The technical solution is as follows:

[0006] This disclosure provides a control system for hydraulic cylinders, used to control the synchronous movement of at least two hydraulic cylinders. The control system includes a pump assembly, at least two control valve assemblies, a detection component, and an electronic control component. The pump assembly is connected to the oil inlet of each of the at least two control valve assemblies, and the at least two control valve assemblies correspond one-to-one with the at least two hydraulic cylinders. Each control valve assembly is connected to the rod chamber and rodless chamber of the corresponding hydraulic cylinder. The detection component is connected to the piston rod of each hydraulic cylinder and is configured to detect the load force and displacement of the piston rod in each hydraulic cylinder. The electronic control component is electrically connected to the detection component and each control valve assembly, and is configured to control the opening size of the control valve assembly corresponding to each hydraulic cylinder based on the load force and displacement of the piston rod in each hydraulic cylinder detected by the detection component, so that the displacement of the piston rod of each hydraulic cylinder is the same.

[0007] In another implementation of this disclosure, the electronic control component is configured to: control the opening size of the control valve group corresponding to each hydraulic cylinder according to the load force of the piston rod in each hydraulic cylinder detected by the detection component, until the pressure established in the rodless chamber of each hydraulic cylinder is equal to its theoretical pressure; after the pressure in the rodless chamber of the hydraulic cylinder is equal to the theoretical pressure, control the opening size of the control valve group corresponding to each hydraulic cylinder in real time according to the displacement detected by the detection component, so that the displacement of the piston rod of each hydraulic cylinder is the same.

[0008] In another implementation of this disclosure, the electronic control component is used to: when lifting the load, if the displacement detected by the detection component is greater than a target value, control the opening of the control valve group connected to the hydraulic cylinder detected by the detection component to decrease; if the displacement detected by the detection component is less than the target value, control the opening of the control valve group connected to the hydraulic cylinder detected by the detection component to increase; or, when lowering the load, if the displacement detected by the detection component is less than the target value, control the opening of the control valve group connected to the hydraulic cylinder detected by the detection component to decrease; if the displacement detected by the detection component is greater than the target value, control the opening of the control valve group connected to the hydraulic cylinder detected by the detection component to increase; wherein, the target value is the displacement value of any one of the at least two hydraulic cylinders detected by the detection component.

[0009] In another implementation of this disclosure, the detection component includes at least two pin force sensors and at least two displacement sensors; the at least two pin force sensors are arranged in a one-to-one correspondence with the at least two hydraulic cylinders, and each of the at least two pin force sensors is connected to the piston rod of the corresponding hydraulic cylinder; the at least two displacement sensors are arranged in a one-to-one correspondence with the at least two hydraulic cylinders, and each of the at least two displacement sensors is connected to the piston of the corresponding hydraulic cylinder.

[0010] In another implementation of this disclosure, the detection component further includes at least two pressure sensors, which are arranged in a one-to-one correspondence with the at least two hydraulic cylinders. Each of the at least two pressure sensors is connected to the rodless chamber of the corresponding hydraulic cylinder. The electronic control component is electrically connected to the at least two pressure sensors and is further configured to: control each of the control valve groups to close if the difference between a first difference and a second difference is greater than a threshold value. The first difference is the difference between the detection values ​​of the first pressure sensor and the second pressure sensor, and the second difference is the difference between the theoretical pressure of the rodless chamber of the first hydraulic cylinder and the theoretical pressure of the rodless chamber of the second hydraulic cylinder. The first pressure sensor is connected to the first hydraulic cylinder, and the second pressure sensor is connected to the second hydraulic cylinder. The first pressure sensor and the second pressure sensor are any two of the at least two pressure sensors.

[0011] In another implementation of this disclosure, the pump set includes an electric motor, a drive pump body, a variable displacement cylinder, and a constant pressure control valve. The electric motor is connected to the drive pump body, and the return port of the drive pump body is connected to the rod chamber of the variable displacement cylinder, the inlet of the constant pressure control valve, and the control port of the constant pressure control valve. The piston rod of the variable displacement cylinder is connected to the variable displacement mechanism of the drive pump body to reduce the displacement of the drive pump body when the piston rod of the variable displacement cylinder extends out of the rod chamber, or to increase the displacement of the drive pump body when the piston rod of the variable displacement cylinder retracts into the rod chamber. The constant pressure control valve is a hydraulically controlled two-position three-way directional valve. The return port of the constant pressure control valve is connected to an oil tank, and the control port of the constant pressure control valve is connected to its own inlet. The working port of the constant pressure control valve is connected to the rodless chamber of the variable displacement cylinder.

[0012] In another implementation of this disclosure, the pump set further includes a load-sensitive valve, a proportional flow valve, and a pilot-operated proportional pressure reducing valve; the inlet of the load-sensitive valve is connected to the return port of the drive pump body, the inlet of the constant pressure control valve, the first port of the proportional flow valve, and the inlet of the pilot-operated proportional pressure reducing valve, respectively; the working port of the load-sensitive valve is connected to the return port of the constant pressure control valve; the return port of the load-sensitive valve is connected to the oil tank; and the control port of the load-sensitive valve is connected to its own inlet; the spring chamber of the load-sensitive valve is connected to the second port of the proportional flow valve; the control port of the proportional flow valve is connected to the working port of the pilot-operated proportional pressure reducing valve; and the return port of the pilot-operated proportional pressure reducing valve is connected to the oil tank.

[0013] In another implementation of this disclosure, the pump set further includes a main safety valve, the oil inlet of which is connected to its own control oil port and the spring chamber of the load-sensitive valve, and the oil return port of the main safety valve is connected to the oil tank; the spring chamber of the main safety valve is connected to the oil inlet of the load-sensitive valve.

[0014] In another implementation of this disclosure, the pump set further includes a pilot proportional relief valve and a pilot safety valve. The inlet of the pilot proportional relief valve is connected to the inlet of the pilot safety valve, the spring chamber of the constant pressure control valve, and the spring chamber of the main safety valve, respectively. The return port of the pilot proportional relief valve is connected to the oil tank, and the control port of the pilot proportional relief valve is connected to its own inlet. The return port of the pilot safety valve is connected to the oil tank, and the control port of the pilot safety valve is connected to its own inlet.

[0015] In another implementation of this disclosure, the control valve group includes a proportional directional valve, a balance valve, and a pilot proportional directional valve; the inlet of the proportional directional valve is connected to the return port of the pump group, the return port of the proportional directional valve is connected to the oil tank, the first working port of the proportional directional valve is connected to the first port of the balance valve, the second working port of the proportional directional valve is connected to the inlet of the pilot proportional directional valve and the rod chamber of the hydraulic cylinder corresponding to the control valve group, respectively; the second port of the balance valve is connected to the rodless chamber of the hydraulic cylinder corresponding to the control valve group, and the control port of the balance valve is connected to the working port of the pilot proportional directional valve.

[0016] The beneficial effects of the technical solutions provided in this disclosure are:

[0017] When the control system provided in this embodiment performs synchronous control of the hydraulic cylinders, the detection component in the control system is configured to detect the load force of the piston rod in each hydraulic cylinder. Simultaneously, the electronic control component is configured to control the opening size of each control valve group based on the different load forces detected by the detection component, thereby ensuring that the displacement of the piston rod in each hydraulic cylinder is the same. Thus, during the actual lifting of the load, the pressure in the rodless chamber of the hydraulic cylinder is determined by the load; the greater the load, the greater the pressure in the rodless chamber, and vice versa. Therefore, given that the load force of the piston rod in each hydraulic cylinder is determined, the theoretical pressure in the rodless chamber of each hydraulic cylinder can be calculated, thereby obtaining the pressure difference between the inlet and outlet oil pressures of each control valve group. Then, based on the pressure difference, the opening size of the two control valve groups can be adjusted to allow the oil to quickly enter the rodless chambers of different hydraulic cylinders, enabling rapid pressure build-up within the rodless chambers. Meanwhile, since the detection component can also control the opening size of the control valve group corresponding to each hydraulic cylinder based on the detected displacement of the piston rod in each hydraulic cylinder, so that the displacement of the piston rod of each hydraulic cylinder is the same, the piston rods of the two hydraulic cylinders can extend and retract at the same speed and with the same displacement, thereby smoothly lifting the biased load. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of a control system for a hydraulic cylinder provided in an embodiment of this disclosure;

[0020] Figure 2 This is a schematic diagram of another hydraulic cylinder control system provided in an embodiment of this disclosure.

[0021] The symbols in the diagram represent the following meanings:

[0022] 1. Pump set; 11. Electric motor; 12. Drive pump body; 13. Variable displacement cylinder; 14. Constant pressure control valve; 15. Load-sensitive valve; 16. Proportional flow valve; 17. Pilot-operated proportional pressure reducing valve; 18. Main safety valve; 19. Pilot-operated proportional relief valve; 110. Pilot-operated safety valve; 111. Pump body electrical control components;

[0023] 2. Control valve assembly; 21. Proportional directional valve; 22. Balancing valve; 23. Pilot-operated proportional directional valve; 24. Shuttle valve; 25. Differential pressure compensator; 26. Safety control valve; 27. Filter;

[0024] 3. Detection components; 31. Pin force sensor; 32. Displacement sensor; 33. Pressure sensor;

[0025] 4. Electronic control components;

[0026] 100. Hydraulic cylinder; 200. Lifting beam; 300. Load. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0028] This disclosure provides a control system for a hydraulic cylinder, such as... Figure 1 As shown, the control system can control two hydraulic cylinders 100 to drive the lifting beam 200 to rise and fall. Two hydraulic cylinders 100 are located at the bottom of the lifting beam 200. A load 300 is located at the top of the lifting beam 200.

[0029] Two hydraulic cylinders 100 are symmetrically arranged at both ends of the lifting beam 200. The piston rod of each hydraulic cylinder 100 is hinged to the lifting beam 200 via a pin. To ensure that the lifting beam does not tilt and pull the piston rod during movement, the control system drives the piston rods of the two hydraulic cylinders 100 to extend synchronously. However, in actual operation, the center of gravity of the load 300 is not necessarily located on the plane of symmetry between the two hydraulic cylinders 100 (the distance from the load 300 to the two hydraulic cylinders...). Figure 1 Since a and b are different (the load lifted by the lifting beam is an offset load), the piston rods of the two hydraulic cylinders 100 have different load forces to support the lifting beam, and the pressure in the rodless chamber of the two hydraulic cylinders 100 is different.

[0030] When the pressures in the rodless chambers of the two hydraulic cylinders 100 are different, if the two hydraulic cylinders 100 are controlled according to the control system in the relevant technology, since the rodless chambers of the two hydraulic cylinders 100 are connected by pipelines, the oil pressure in the rodless chambers of the two hydraulic cylinders is the same. However, because the piston rods of the two hydraulic cylinders 100 bear different loads supporting the lifting beam, the piston rod of the hydraulic cylinder bearing a larger load will extend at a slower speed due to the larger load, in order to further increase the oil pressure in the rodless chamber to balance the load. Conversely, the piston rod of the hydraulic cylinder bearing a smaller load will extend at a faster speed due to the smaller load, in order to further decrease the oil pressure in the rodless chamber to balance the load. As a result, the extension and retraction speeds of the piston rods of the two hydraulic cylinders 100 are different, and their displacements are also different. That is, the control system in the relevant technology cannot achieve synchronous control of the hydraulic cylinders 100.

[0031] It should be noted that the number of hydraulic cylinders 100 mentioned above is for illustrative purposes only and is not a limitation. It can be set as needed, for example, controlling three or four hydraulic cylinders 100 to move synchronously.

[0032] Therefore, this disclosure provides a control system capable of controlling the synchronous movement of at least two hydraulic cylinders. Here, synchronous movement means that the displacement of the piston rods of at least two hydraulic cylinders always remains the same.

[0033] In this embodiment, the same displacement of the piston rod of each hydraulic cylinder 100 means that the displacement of the piston rod of each hydraulic cylinder 100 is equal or the difference between them is within a certain range (e.g., within 0.1mm).

[0034] See also Figure 1 The control system includes a pump group 1, at least two control valve groups 2, a detection component 3, and an electrical control component 4. The pump group 1 is connected to the oil inlet of each of the at least two control valve groups 2, and the at least two control valve groups 2 correspond one-to-one with at least two hydraulic cylinders 100. The control valve groups 2 are respectively connected to the rod chamber and rodless chamber of the corresponding hydraulic cylinder 100.

[0035] The detection component 3 is connected to the piston rod of each hydraulic cylinder 100, and is configured to detect the load force on the piston rod of each hydraulic cylinder 100. The electrical control component 4 is electrically connected to the detection component 3 and each control valve group 2, and is configured to control the opening size of the control valve group 2 corresponding to each hydraulic cylinder 100 based on the load force and displacement of the piston rod in each hydraulic cylinder 100 detected by the detection component 3, so that the displacement of the piston rod of each hydraulic cylinder 100 is the same.

[0036] When the control system provided in this embodiment performs synchronous control of the hydraulic cylinders, the detection component 3 in the control system is configured to detect the load force of the piston rod in each hydraulic cylinder 100. Simultaneously, the electronic control component 4 is configured to control the opening size of each control valve group 2 according to the different load forces detected by the detection component 3, so as to control the displacement of the piston rods of each hydraulic cylinder 100 to be the same. Thus, during the actual lifting of the load, the pressure in the rodless chamber of the hydraulic cylinder is determined by the load. The larger the load, the greater the pressure in the rodless chamber; the smaller the load, the smaller the pressure in the rodless chamber. Therefore, given that the load force of the piston rod in each hydraulic cylinder 100 has been determined, the theoretical pressure in the rodless chamber of each hydraulic cylinder 100 can be calculated, thereby obtaining the pressure difference between the inlet and outlet oil pressures of each control valve group 2. Then, based on the pressure difference, the opening size of each control valve group 2 can be adjusted to allow the oil to quickly enter the rodless chambers of different hydraulic cylinders, and pressure can be quickly established in the rodless chambers. Meanwhile, since the detection component 3 can also control the opening size of the control valve group 2 corresponding to each hydraulic cylinder 100 according to the displacement of the piston rod in each hydraulic cylinder 100, so that the displacement of the piston rod of each hydraulic cylinder 100 is the same, the piston rods of the two hydraulic cylinders can extend and retract at the same speed and with the same displacement, thereby smoothly lifting the biased load.

[0037] Optionally, the electronic control component 4 is configured to control the opening size of the control valve group 2 corresponding to each hydraulic cylinder 100 according to the load force of the piston rod in each hydraulic cylinder 100 detected by the detection component 3, until the pressure established in the rodless chamber of each hydraulic cylinder 100 is equal to its respective theoretical pressure.

[0038] Based on the displacement detected by the detection component 3, the opening size of the control valve group 2 corresponding to the hydraulic cylinder 100 is controlled in real time so that the displacement of the piston rod of each hydraulic cylinder 100 is the same.

[0039] In the above implementation, the electronic control component 4 is configured with the above control method. This allows the theoretical pressure of the rodless chamber of each hydraulic cylinder 100 to be obtained based on the load force of the piston rod during lifting. Then, the opening size of the corresponding control valve group 2 is adjusted according to the theoretical pressure, enabling rapid pressure build-up in the rodless chamber of each hydraulic cylinder 100, thereby improving the response and control accuracy of the control system. This is because simply building pressure through the load would be time-consuming. Once the pressure in the rodless chamber of the hydraulic cylinder 100 reaches the theoretical pressure, the displacement of each hydraulic cylinder 100 is monitored in real time to achieve closed-loop control of the control system, ensuring that the displacements of the hydraulic cylinders 100 are identical and guaranteeing smooth lifting and lowering of the load.

[0040] In this embodiment, the electronic control component 4 is used to: when lowering the load, if the displacement detected by the detection component 3 is greater than the target value, control the opening of the control valve group 2 connected to the hydraulic cylinder 100 detected by the detection component 3 to increase; if the displacement detected by the detection component 3 is less than the target value, control the opening of the control valve group 2 connected to the hydraulic cylinder 100 detected by the detection component 3 to decrease.

[0041] Alternatively, when lifting a load, if the displacement detected by detection component 3 is greater than the target value, the opening of control valve group 2 connected to the hydraulic cylinder 100 detected by detection component 3 will decrease. If the displacement detected by detection component 3 is less than the target value, the opening of control valve group 2 connected to the hydraulic cylinder 100 detected by detection component 3 will increase. The target value is the displacement value of any one of the at least two hydraulic cylinders detected by detection component 3.

[0042] When lifting a load, if the displacement of one hydraulic cylinder 100 is greater than the displacement of the other remaining hydraulic cylinders, it indicates that the piston rod extension speed of that hydraulic cylinder 100 is high. In this case, it is necessary to reduce the extension speed of the piston rod of that hydraulic cylinder 100, which also requires reducing the flow rate of oil entering the rodless chamber of that hydraulic cylinder 100. Therefore, the opening size of the control valve assembly 2 needs to be reduced. Conversely, if the displacement of one hydraulic cylinder 100 is less than the displacement of the other remaining hydraulic cylinders, it indicates that the piston rod extension speed of that hydraulic cylinder 100 is low. In this case, it is necessary to increase the extension speed of the piston rod of that hydraulic cylinder 100, which also requires increasing the flow rate of oil entering the rodless chamber of that hydraulic cylinder 100. Therefore, the opening size of the control valve assembly 2 needs to be increased.

[0043] When the load is released, if the displacement of one hydraulic cylinder 100 is greater than the displacement of the other remaining hydraulic cylinders, it indicates that the piston rod retraction speed of that hydraulic cylinder 100 is slow. In this case, it is necessary to increase the retraction speed of the piston rod of that hydraulic cylinder 100, which requires increasing the flow rate of oil entering the rod chamber of the hydraulic cylinder 100 and increasing the flow rate of oil exiting the rodless chamber of the hydraulic cylinder 100. Therefore, the opening size of the control valve assembly 2 needs to be increased. Conversely, if the displacement of one hydraulic cylinder 100 is less than the displacement of the other remaining hydraulic cylinders, it indicates that the piston rod retraction speed of that hydraulic cylinder 100 is fast. In this case, it is necessary to decrease the retraction speed of the piston rod of that hydraulic cylinder 100, which requires decreasing the flow rate of oil entering the rod chamber of the hydraulic cylinder 100 and decreasing the flow rate of oil exiting the rodless chamber of the hydraulic cylinder 100. Therefore, the opening size of the control valve assembly 2 needs to be decreased.

[0044] For safety reasons, the target value mentioned above is the minimum displacement value among the displacements corresponding to at least two displacement sensors 32.

[0045] Figure 2 This is a schematic diagram of another hydraulic cylinder control system provided in this disclosure embodiment, combined with... Figure 2 Optionally, the detection component 3 includes at least two pin force sensors 31, which are arranged in a one-to-one correspondence with at least two hydraulic cylinders 100, and each of the at least two pin force sensors 31 is connected to the piston rod of the corresponding hydraulic cylinder 100.

[0046] The detection component 3 also includes at least two displacement sensors 32, which are arranged in a one-to-one correspondence with at least two hydraulic cylinders 100, and each of the at least two displacement sensors 32 is connected to the piston of the corresponding hydraulic cylinder 100.

[0047] In the above implementation, the pin force sensor 31 is used to detect the load force of the piston rod of the hydraulic cylinder 100 corresponding to the pin force sensor 31. When lifting the load, the pin force sensor 31 detects the load force of the piston rods of the two hydraulic cylinders 100, and then transmits the detected load force to the electronic control component 4. The electronic control component 4 can then calculate the theoretical pressure of the rodless chamber of each hydraulic cylinder 100 based on the load force. For example, the pin force sensor 31 detects the load force of the piston rods of the two hydraulic cylinders 100 in real time, which is the lifting force F when lifting the load. According to the working principle of the hydraulic cylinder, when the piston rod needs to provide the lifting force F when lifting or lowering the load, the theoretical pressure of the rodless chamber of the hydraulic cylinder is P = F / S, where S is the area of ​​the piston.

[0048] Since the outlet end of control valve group 2 is connected to the rodless chamber of hydraulic cylinder 100, the electrical control component 4 calculates the theoretical pressure of the rodless chamber of each hydraulic cylinder 100 based on the load force, and thus naturally obtains the oil pressure at the outlet end of each control valve group 2. Combined with the operating parameters of pump group 1, the oil pressure entering the inlet end of each control valve group 2 can be obtained. This allows us to obtain the pressure difference between the inlet and outlet oil pressures of each control valve group 2. Because the flow rate of control valve group 2 has a definite mathematical relationship with the pressure difference between the inlet and outlet oil pressures and its own opening size—for example, when control valve group 2 is a proportional valve group, the flow rate of control valve group 2 = the product of the half power of the pressure difference between the inlet and outlet oil pressures and its own opening size—we can quickly make the pressure in the rodless chamber of each hydraulic cylinder reach the theoretical pressure, given the known pressure difference between the inlet and outlet oil pressures of the two control valve groups 2, to obtain the opening size of each control valve group 2. Then, based on the opening size of the control valve group 2, we adjust the openings of the two control valve groups 2 so that the pressure in the rodless chamber of each hydraulic cylinder 100 quickly reaches the theoretical pressure.

[0049] Displacement sensor 32 is used to detect the displacement (i.e., stroke) of the piston rods of the two hydraulic cylinders 100 in real time. When the piston rod of the hydraulic cylinder 100 extends to lift the biased load, the displacement sensor 32 can detect the displacement of the piston rod of the hydraulic cylinder 100 in real time. The displacement sensor 32 transmits the detected displacement to the electronic control component 4. The electronic control component 4 controls the opening size of each control valve group 2 according to the displacement closed loop, so that the flow rate entering the two hydraulic cylinders is the same, realizing the displacement closed loop control of a single hydraulic cylinder and the displacement synchronous control of multiple hydraulic cylinders.

[0050] The opening size of the control valve assembly 2 mentioned above includes the size of the communication opening when the control valve assembly 2 is connected to the rodless chamber of the hydraulic cylinder 100, and the size of the communication opening when the control valve assembly 2 is connected to the rod chamber of the hydraulic cylinder 100.

[0051] In this embodiment, when lifting the load, the control valve assembly 2 inputs oil into the rodless chamber of the hydraulic cylinder 100. At this time, the opening size of the control valve assembly 2 is the size of the communication opening corresponding to the connection between the control valve assembly 2 and the rodless chamber of the hydraulic cylinder 100. By adjusting the opening size of the control valve assembly 2, the flow rate of oil entering the rodless chamber of the hydraulic cylinder 100 can be adjusted, thereby adjusting the extension speed of the piston rod of the hydraulic cylinder 100.

[0052] When lowering the load, control valve assembly 2 supplies oil to the rod chamber of hydraulic cylinder 100, while simultaneously discharging oil from the rodless chamber. At this time, the opening size of control valve assembly 2 includes both the size of the communication opening when control valve assembly 2 is connected to the rod chamber of hydraulic cylinder 100 and the size of the communication opening when control valve assembly 2 is connected to the rodless chamber of hydraulic cylinder 100. By adjusting the opening size of control valve assembly 2, the relative flow rate of oil entering and exiting hydraulic cylinder 100 can be controlled, thereby adjusting the retraction speed of the piston rod of hydraulic cylinder 100. That is, when lowering the load, if the opening size of the control valve assembly 2 is increased to increase the size of the corresponding communication opening when the control valve assembly 2 is connected to the rod chamber of the hydraulic cylinder 100, and the size of the corresponding communication opening when the control valve assembly 2 is connected to the rodless chamber of the hydraulic cylinder 100, then the flow rate of the oil entering the rod chamber of the hydraulic cylinder 100 increases, and at the same time, the flow rate of the oil flowing out of the rodless chamber of the hydraulic cylinder 100 also increases, and the retraction speed of the piston rod of the hydraulic cylinder 100 accelerates.

[0053] In addition, for safety reasons, the detection component 3 also includes at least two pressure sensors 33, which are arranged one-to-one with at least two hydraulic cylinders 100. Each of the at least two pressure sensors 33 is connected to the rodless chamber of the corresponding hydraulic cylinder 100.

[0054] The electronic control component 4 is electrically connected to at least two pressure sensors 33, and the electronic control component 4 is also configured to control each control valve group 2 to close if the difference between the first difference and the second difference is greater than a threshold.

[0055] The first difference is the difference between the detection values ​​of the first pressure sensor and the second pressure sensor, and the second difference is the difference between the theoretical pressure of the rodless chamber of the first hydraulic cylinder and the theoretical pressure of the rodless chamber of the second hydraulic cylinder. The first pressure sensor is connected to the first hydraulic cylinder, and the second pressure sensor is connected to the second hydraulic cylinder. The first pressure sensor and the second pressure sensor are any two of at least two pressure sensors 33.

[0056] Pressure sensor 33 is used to detect the actual pressure in the rodless chamber of hydraulic cylinder 100 in real time. When the actual working pressure difference between the rodless chambers of any two hydraulic cylinders 100 exceeds a certain range of the theoretical pressure difference, such as 2 MPa, the electronic control component 4 controls the control valve group 2 to close, and the hydraulic cylinder stops operating, thus achieving safety protection.

[0057] Combination Figure 2 Taking lifting load as an example, the inlet pressure of control valve group 2 is the same, for example, 20MPa. Assume the load on the right hydraulic cylinder is large, and the load on the left hydraulic cylinder is small. For example, the theoretical pressure of the rodless chamber of the right hydraulic cylinder is 16MPa, and the theoretical pressure of the rodless chamber of the left hydraulic cylinder is 11MPa, with a theoretical pressure difference of 5MPa. If pressure sensor 33 detects an actual working pressure difference of 7MPa, exceeding the theoretical pressure difference by 2MPa, it indicates that one hydraulic cylinder is overloaded and the other is underloaded, potentially causing the two hydraulic cylinders to be out of sync. Therefore, the hydraulic cylinders need to stop operating to achieve safety protection.

[0058] See also Figure 2 Optionally, the pump unit 1 includes an electric motor 11, a drive pump body 12, a variable cylinder 13, and a constant pressure control valve 14. The electric motor 11 is connected to the drive pump body 12, and the oil return port of the drive pump body 12 is connected to the rod chamber of the variable cylinder 13 and the oil inlet of the constant pressure control valve 14, respectively.

[0059] The piston rod of the variable displacement cylinder 13 is connected to the variable displacement mechanism of the drive pump body 12, so as to reduce the displacement of the drive pump body 12 when the piston rod of the variable displacement cylinder 13 extends, and increase the displacement of the drive pump body 12 when the piston rod of the variable displacement cylinder 13 retracts. The constant pressure control valve 14 is a hydraulically controlled two-position three-way directional valve. The return port of the constant pressure control valve 14 is connected to the oil tank, and the control port of the constant pressure control valve 14 is connected to its own inlet port. The working port of the constant pressure control valve 14 is connected to the rodless chamber of the variable displacement cylinder 13.

[0060] In the above implementation, the electric motor 11 is used to drive the drive pump body 12 to work, and the drive pump body 12 is used to pressurize the oil in the oil tank and pump it to the control valve group 2.

[0061] The variable displacement cylinder 13 is connected to the variable displacement mechanism of the drive pump body 12 to regulate the displacement of the drive pump body 12, thereby controlling the flow rate of oil entering the hydraulic cylinder 100 from the source, avoiding overspeed, and improving the safety of the control system.

[0062] The constant pressure control valve 14 is connected to the variable cylinder 13 to control the flow rate and pressure of the oil in the rodless chamber of the variable cylinder 13, thereby controlling the extension and retraction of the piston rod of the variable cylinder 13.

[0063] For example, when the oil pressure difference between the control port x of the constant pressure control valve 14 and the spring chamber y is greater than the spring force, the constant pressure control valve 14 operates in the right position, the return port T of the constant pressure control valve 14 is blocked, and the oil in the constant pressure control valve 14 flows from the inlet port P to the working port A, i.e., P→A. The oil pumped out by the driving pump body 12 enters the rodless chamber of the variable cylinder 13 through the constant pressure control valve 14, the piston rod of the variable cylinder 13 extends, and the displacement of the driving pump body 12 decreases. When the pressure difference between the control port x of the constant pressure control valve 14 and the oil pressure at the spring chamber y is not greater than the spring force, the constant pressure control valve 14 operates in the left position, the oil inlet P of the constant pressure control valve 14 is blocked, and the oil in the constant pressure control valve 14 flows from the working port A to the return port T, i.e., A→T. The oil pumped out by the driving pump body 12 enters the rod chamber of the variable cylinder 13 through the constant pressure control valve 14, the piston rod of the variable cylinder 13 retracts, and the displacement of the driving pump body 12 increases.

[0064] Optionally, the pump unit 1 further includes a load-sensitive valve 15, a proportional flow valve 16, and a pilot-operated proportional pressure reducing valve 17. The inlet of the load-sensitive valve 15 is connected to the return port of the drive pump body 12, the inlet of the constant pressure control valve 14, the first port of the proportional flow valve 16, and the inlet of the pilot-operated proportional pressure reducing valve 17, respectively. The working port A of the load-sensitive valve 15 is connected to the return port of the constant pressure control valve 14, and the return port of the load-sensitive valve 15 is connected to the oil tank. The control port of the load-sensitive valve 15 is connected to its own inlet. The spring chamber of the load-sensitive valve 15 is connected to the second port of the proportional flow valve 16, the control port of the proportional flow valve 16 is connected to the working port of the pilot-operated proportional pressure reducing valve 17, and the return port of the pilot-operated proportional pressure reducing valve 17 is connected to the oil tank.

[0065] In the above implementation, when the pressure difference between the control port x of the load-sensitive valve 15 and the pressure at the spring chamber y port is less than the spring force, the load-sensitive valve 15 operates in the left position, that is, the inlet P of the load-sensitive valve 15 is blocked, and the oil flows from A to T. The oil in the rodless chamber of the variable cylinder 13 flows out through the constant pressure control valve 14 and the load-sensitive valve 15, and the piston rod of the variable cylinder 13 retracts, driving the pump body 12 to increase its displacement. Conversely, when the pressure between the control port x of the load-sensitive valve 15 and the pressure at the spring chamber y port is greater than the spring force, the load-sensitive valve 15 operates in the right position, that is, the return port T of the load-sensitive valve 15 is blocked, and the oil flows from P to A. The oil in the return port P of the pump body 12 enters the rodless chamber of the variable cylinder 13 through the load-sensitive valve 15, and the piston rod of the variable cylinder 13 extends, driving the pump body 12 to decrease its displacement.

[0066] Because the position of the valve core of the load-sensitive valve 15 is directly limited by the relationship between the oil pressure at the control port x and the spring chamber y, and the inlet P of the load-sensitive valve 15 is connected to the first port A of the proportional flow valve 16, and the spring chamber y of the load-sensitive valve 15 is connected to the second port B of the proportional flow valve 16, the load-sensitive valve 15 can stabilize the pressure difference between the first port A and the second port B of the proportional flow valve 16. When the pressure difference is less than the spring force of the load-sensitive valve 15, the load-sensitive valve 15 operates in the left position, driving the pump body 12 to increase its displacement until the pressure difference equals the spring force of the load-sensitive valve 15. When the pressure difference between the first port A and the second port B of the proportional flow valve 16 is greater than the spring force of the load-sensitive valve 15, the load-sensitive valve 15 operates in the right position, driving the pump body 12 to decrease its displacement until the pressure difference equals the spring force of the load-sensitive valve 15. The load-sensitive valve 15 makes the flow rate of the proportional flow valve 16 only related to its opening size, achieving flow regulation independent of the load pressure. The pilot-operated proportional pressure reducing valve 17 is used to remotely adjust the x-pressure of the control port of the proportional flow valve 16, that is, to steplessly adjust the opening size and flow rate of the proportional flow valve 16. Additionally, to limit the oil flow direction between the working port A of the load-sensitive valve 15 and the working port A of the constant pressure control valve 14, a right-hand check valve is connected between them. The inlet of the check valve is connected to the working port A of the load-sensitive valve 15, and the return port of the check valve is connected to the working port A of the constant pressure control valve 14.

[0067] Optionally, the pump unit 1 also includes a main safety valve 18. The oil inlet of the main safety valve 18 is connected to its own control oil port and the spring chamber of the load-sensitive valve 15, respectively. The oil return port of the main safety valve 18 is connected to the oil tank. The spring chamber of the main safety valve 18 is connected to the oil inlet of the load-sensitive valve 15.

[0068] In the above implementation, when the pressure at the second port B of the proportional flow valve 16 is greater than the set pressure of the main safety valve 18, the inlet P of the main safety valve 18 is connected to the return port T, and the oil flows from P to T. The oil at the spring chamber y port of the load-sensitive valve 15 flows back to the oil tank through the main safety valve 18, and the load-sensitive valve 15 operates in the right position, driving the pump body 12 to reduce its displacement, thereby achieving safety protection.

[0069] Optionally, the pump unit 1 further includes a pilot proportional relief valve 19 and a pilot safety valve 110. The inlet of the pilot proportional relief valve 19 is connected to the inlet of the pilot safety valve 110, the spring chamber of the constant pressure control valve 14, and the spring chamber of the main safety valve 18, respectively. The return port of the pilot proportional relief valve 19 is connected to the oil tank, and the control port of the pilot proportional relief valve 19 is connected to its own inlet. The return port of the pilot safety valve 110 is connected to the oil tank, and the control port of the pilot safety valve 110 is connected to its own inlet.

[0070] In the above implementation, the pilot proportional relief valve 19 is used to remotely adjust the constant pressure setting value of the drive pump body 12 and the pressure setting value of the main safety valve 18. The pilot safety valve 110 is used to mechanically limit the maximum pressure setting value, i.e., pressure limiting safety protection.

[0071] In addition, to facilitate control of the opening size of the proportional flow valve 16, a flow meter is connected to the second working port of the proportional flow valve 16. The pump unit 1 also includes a pump body electrical control 111, which is electrically connected to the flow meter and the pilot proportional pressure reducing valve 17 respectively.

[0072] Optionally, the control valve assembly 2 includes a proportional directional valve 21, a balance valve 22, and a pilot-operated proportional directional valve 23. The inlet of the proportional directional valve 21 is connected to the return port of the pump assembly 1, and the return port of the proportional directional valve 21 is connected to the oil tank. The first working port of the proportional directional valve 21 is connected to the inlet of the balance valve 22, and the second working port of the proportional directional valve 21 is connected to both the inlet of the pilot-operated proportional directional valve 23 and the rod chamber of the hydraulic cylinder corresponding to the control valve assembly 2. The return port of the balance valve 22 is connected to the rodless chamber of the hydraulic cylinder corresponding to the control valve assembly 2, and the control port of the balance valve 22 is connected to the working port of the pilot-operated proportional directional valve 23.

[0073] When the proportional directional valve 21 is in its right position, i.e., when lifting the load, the oil in the proportional directional valve 21 flows from P→A and B→T. The pressurized oil at the first working port A of the proportional directional valve 21 enters the rodless chamber of the hydraulic cylinder 100 through the one-way function of the left position of the balance valve 22. The oil in the rod chamber of the hydraulic cylinder 100 flows back to the oil tank through the second working port B and the return port T of the proportional directional valve 21. At the same time, the pilot proportional directional valve 23 is de-energized and operates in its lower position under the action of spring force. The inlet port P of the pilot proportional directional valve 23 is blocked, and the working port A and the return port T of the pilot proportional directional valve 23 are connected, with the oil flowing from A→T. The pilot proportional directional valve 23 cannot control the balance valve 22 to be in the right-hand throttling position; the balance valve 22 remains in the left-hand position. At this time, the opening of the control valve group 2 is the same as the opening size of the proportional directional valve 21. The larger the opening of the proportional directional valve 21, the greater the flow rate of oil entering the rodless chamber of the hydraulic cylinder 100, the greater the extension speed of the piston rod of the hydraulic cylinder 100, and the greater the displacement of the hydraulic cylinder 100 per unit time. Therefore, the extension speed of the piston rod of the hydraulic cylinder 100 can be controlled by controlling the opening of the proportional directional valve 21 through the electronic control component 4.

[0074] When the proportional directional valve 21 is in its left position, the oil in the proportional directional valve 21 flows from P→B and A→T, and the oil enters the rod chamber of the hydraulic cylinder 100 from the second working port B of the proportional directional valve 21. Simultaneously, the pilot proportional directional valve 23 is energized, and its upper position is activated. The inlet port P of the pilot proportional directional valve 23 connects with the working port A, while the return port T is blocked, allowing oil to flow from P→A and T. The pressurized oil at the second working port B of the proportional directional valve 21 also flows through the pilot proportional directional valve 23 to the control port x of the balance valve 22, pushing the balance valve 22 to the right-hand throttling position. The oil in the rodless chamber of the hydraulic cylinder flows back to the oil tank through the balance valve and the first working port A→T of the proportional directional valve 21. At this time, the openings of the control valve assembly 2 include the opening of the proportional directional valve 21 and the throttling opening of the balance valve 22. The larger the opening of the proportional directional valve 21, the greater the flow rate of oil entering the rod chamber of the hydraulic cylinder 100. The larger the throttling opening of the balance valve 22, the greater the flow rate of oil exiting the rodless chamber of the hydraulic cylinder 100. Consequently, the piston rod retraction speed of the hydraulic cylinder 100 is greater, and the displacement of the hydraulic cylinder 100 per unit time is greater. The throttling opening of the balance valve 22 is limited by the opening size of the pilot proportional directional valve 23; the larger the opening of the pilot proportional directional valve 23, the larger the throttling opening of the balance valve 22. Therefore, the retraction speed of the piston rod of the hydraulic cylinder 100 can be controlled by controlling the openings of the proportional directional valve 21 and the pilot proportional directional valve 23 through the electronic control component 4.

[0075] Optionally, the control valve assembly 2 also includes a shuttle valve 24 and a differential pressure compensator 25. The shuttle valve 24 is connected between the proportional directional valve 21 and the balance valve 22. The first port of the shuttle valve 24 is connected to the first working port of the proportional directional valve 21, and the second port of the shuttle valve 24 is connected to the second working port of the proportional directional valve 21.

[0076] The differential pressure compensator 25 is connected between the pump set 1 and the proportional directional valve 21. The oil inlet of the differential pressure compensator 25 is connected to the oil return port of the pump set 1, the oil return port of the differential pressure compensator 25 is connected to the oil inlet of the proportional directional valve 21, and the control oil port of the differential pressure compensator 25 is connected to the oil return port of the shuttle valve 24.

[0077] The shuttle valve 24 can transmit the high-pressure side oil pressure in the first working port A and the second working port B of the proportional directional valve 21 to the spring chamber of the differential pressure compensator 25, so that the pressure difference between the oil inlet P of the proportional directional valve 21 and the first working port A and the second working port B is equal to the setting value of the differential pressure compensator 25. This ensures that the flow rate through the proportional directional valve 21 is only related to the size of its valve core opening and is independent of the load, thereby improving the control accuracy of the proportional directional valve 21.

[0078] In other words, the differential pressure compensator 25 is used to stabilize the pressure difference between the inlet and outlet sides of the proportional directional valve 21. The first port A and second port B of the shuttle valve 24 are connected to the first working port A and second working port B of the proportional directional valve 21, respectively. The pressure at the return port C of the shuttle valve 24 is always the higher of the pressures at the first working port A and second working port B of the proportional directional valve 21. When the proportional directional valve 21 is in the right position, P→A, B→T. The pressure at the first working port A of the proportional directional valve 21 is transmitted to the control port x of the differential pressure compensator 25 through the return port C of the shuttle valve 24. The P→A pressure difference of the proportional directional valve 21 is always the spring setting pressure of the differential pressure compensator 25, and the flow rate of the proportional directional valve 21 is only related to its opening size. When the proportional directional valve 21 is in the left position, similar to the above, the oil in the proportional directional valve 21 flows from P→B and A→T. The pressure at the second working port B of the proportional directional valve 21 is transmitted to the control port x of the differential pressure compensator 25 through the return port C of the shuttle valve 24. The P→B ​​differential pressure of the proportional directional valve 21 is always the spring setting pressure of the differential pressure compensator 25, and the flow rate of the proportional directional valve 21 is only related to its opening size.

[0079] Optionally, the control valve assembly 2 also includes a safety control valve 26. The inlet of the safety control valve 26 is connected to the first working port of the proportional directional valve 21 and the first port of the shuttle valve 24, respectively. The return port of the safety control valve 26 is connected to the first port A of the balance valve 22 and the rodless chamber of the hydraulic cylinder corresponding to the control valve assembly 2, respectively. The control port of the safety control valve 26 is connected to its own return port.

[0080] In the above implementation, the safety control valve 26 is used to control the oil pressure entering the second oil port B of the balance valve 22, thereby controlling the oil pressure of the oil entering the rodless chamber of the hydraulic cylinder 100.

[0081] When the pressure at the second port B of the balance valve 22 is greater than the set pressure of the safety control valve 26, the inlet and outlet of the safety control valve 26 are connected, and the oil at the first port A of the balance valve 22 is depressurized and flows back to the oil tank.

[0082] Optionally, the control valve assembly 2 also includes a filter 27, which is connected in the oil line between the shuttle valve 24 and the pilot proportional directional valve 23. The oil inlet of the filter 27 is connected to the second oil port B of the shuttle valve 24, and the oil return port of the filter 27 is connected to the oil inlet P of the pilot proportional directional valve 23.

[0083] The filter 27 is used to filter the oil entering the pilot proportional directional valve 23 to prevent impurities from entering the pilot proportional directional valve 23.

[0084] Optionally, the electronic control component 4 is a controller. The controller can be a computer, microcontroller, or other device equipped with a control program.

[0085] The following is a brief description of the working process of the control system provided in the embodiments of this disclosure:

[0086] Before operation, adjust the control signal of the pilot proportional relief valve 19 in pump set 1 according to the size of the bias load to prevent overload. Adjust the control signal of the pilot proportional pressure reducing valve 17 in pump set 1 according to the lifting or lowering speed requirements to set the output flow of pump set 1 from the source to prevent overspeed.

[0087] When lifting a load, the proportional directional valve 21 operates in its right position. The oil in the proportional directional valve 21 flows from P→A and B→T. The pressure at the first working port A of the proportional directional valve 21 is transmitted to the control port x of the differential pressure compensator 25 via the return port C of the shuttle valve 24. The differential pressure from P to A in the proportional directional valve 21 is always the spring setting pressure of the differential pressure compensator 25; the flow rate is only related to the size of its opening. The pressurized oil at the first working port A of the proportional directional valve 21 enters the rodless chamber of the hydraulic cylinder 100 through the left-hand one-way function of the balance valve 22, pushing the piston rod out. The oil in the rod chamber of the hydraulic cylinder 100 returns to the oil tank via the B→T direction of the proportional directional valve 21. Simultaneously, the pilot proportional directional valve 23 is de-energized and operates in its lower position under the action of the spring force. The inlet port P of the pilot proportional directional valve 23 is blocked, and the oil flows from A→T.

[0088] Simultaneously, the pin force sensor 31 detects the load force on the piston rods of the two hydraulic cylinders 100 in real time. The electronic control component 4 calculates the theoretical pressure and pressure difference of the rodless chambers of the two hydraulic cylinders 100, and the pressure sensor 33 detects the actual working pressure of the rodless chambers of the two hydraulic cylinders 100 in real time. When the actual working pressure difference of the rodless chambers of the two hydraulic cylinders exceeds a certain range of the theoretical pressure difference, such as 2 MPa, the system stops operating to achieve safety protection.

[0089] The displacement sensor 32 detects the displacement of the piston rod in real time and transmits it to the electronic control component 4. The electronic control component 4 controls the proportional directional valve 21 to realize closed-loop displacement control of a single hydraulic cylinder 100 and synchronous displacement control of two hydraulic cylinders.

[0090] When the load is released, the proportional directional valve 21 operates in the left position, and the oil in the proportional directional valve 21 flows through P→B and A→T. The pressure at the second working port B of the proportional directional valve 21 is transmitted to the control port x of the differential pressure compensator 25 through the return port C of the shuttle valve 24. The P→B ​​differential pressure of the proportional directional valve 21 is always the spring setting pressure of the differential pressure compensator 25, and the flow rate is only related to its opening size. The pressurized oil at the second working port B of the proportional directional valve 21 enters the rod chamber of the hydraulic cylinder 100. At the same time, the pilot proportional directional valve 23 is energized and operates in the upper position, blocking the oil flows through P→A and T in the pilot proportional directional valve 23. The pressurized oil at the second working port B of the proportional directional valve 21 also flows through the filter 27 and the pilot proportional directional valve 23 to the control port x of the balance valve 22, driving the balance valve 22 to operate in the right position with throttling function. The oil in the rodless chamber of the hydraulic cylinder 100 returns to the oil tank through the balance valve 22 and the A→T of the proportional directional valve 21.

[0091] Simultaneously, the pin force sensor 31 detects the load force on the piston rods of the two hydraulic cylinders 100 in real time. The electronic control component 4 calculates the theoretical pressure and pressure difference of the rodless chambers of the two hydraulic cylinders 100, and the pressure sensor 33 detects the actual working pressure of the rodless chambers of the two hydraulic cylinders 100 in real time. When the actual working pressure difference of the rodless chambers of the two hydraulic cylinders exceeds a certain range of the theoretical pressure difference, such as 2 MPa, the system stops operating to achieve safety protection.

[0092] By adjusting the control signal of the pilot proportional directional valve 23, the throttle orifice size of the balance valve 22 and the rodless chamber pressure of the hydraulic cylinder 100 can be adjusted to achieve pressure correction. The displacement sensor 32 detects the displacement of the piston rod in real time and transmits it to the electronic control component 4. The electronic control component 4 controls the proportional directional valve 21 to achieve closed-loop displacement control of a single hydraulic cylinder 100 and synchronous displacement control of multiple hydraulic cylinders.

[0093] The above description is merely an optional embodiment of this disclosure and is not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A control system for a hydraulic cylinder, characterized in that, The control system is used to control the synchronous movement of at least two hydraulic cylinders. The control system includes a pump group (1), at least two control valve groups (2), a detection component (3), and an electrical control component (4). The pump group (1) is connected to the oil inlet of each of the at least two control valve groups (2), and the at least two control valve groups (2) correspond one-to-one with the at least two hydraulic cylinders (100). The control valve group (2) is connected to the rod chamber and rodless chamber of the corresponding hydraulic cylinder (100) respectively. The detection component (3) is connected to the piston rod of each of the hydraulic cylinders (100), and the detection component (3) is configured to detect the load force and displacement of the piston rod in each of the hydraulic cylinders (100); The electronic control component (4) is electrically connected to the detection component (3) and each of the control valve groups (2). The electronic control component (4) is configured to: control the opening size of the control valve group (2) corresponding to the hydraulic cylinder (100) according to the load force of the piston rod in each hydraulic cylinder (100) detected by the detection component (3) until the pressure established in the rodless chamber of each hydraulic cylinder (100) is equal to its theoretical pressure; after the pressure in the rodless chamber of the hydraulic cylinder (100) is the theoretical pressure, control the opening size of the control valve group (2) corresponding to the hydraulic cylinder (100) in real time according to the displacement detected by the detection component (3) so that the displacement of the piston rod of each hydraulic cylinder (100) is the same.

2. The control system according to claim 1, characterized in that, The electronic control component (4) is used to: when lifting a load, if the displacement detected by the detection component (3) is greater than the target value, control the opening of the control valve group (2) connected to the hydraulic cylinder (100) detected by the detection component (3) to become smaller; if the displacement detected by the detection component (3) is less than the target value, control the opening of the control valve group (2) connected to the hydraulic cylinder (100) detected by the detection component (3) to become larger. Alternatively, when the load is lowered, if the displacement detected by the detection component (3) is less than the target value, the opening of the control valve group (2) connected to the hydraulic cylinder (100) detected by the detection component (3) is controlled to become smaller; if the displacement detected by the detection component (3) is greater than the target value, the opening of the control valve group (2) connected to the hydraulic cylinder (100) detected by the detection component (3) is controlled to become larger. The target value is the displacement value of any one of the at least two hydraulic cylinders (100) detected by the detection component (3).

3. The control system according to claim 2, characterized in that, The detection component (3) includes at least two pin force sensors (31) and at least two displacement sensors (32). The at least two pin force sensors (31) are arranged in a one-to-one correspondence with the at least two hydraulic cylinders (100), and each of the at least two pin force sensors (31) is connected to the piston rod of the corresponding hydraulic cylinder (100). The at least two displacement sensors (32) are arranged in a one-to-one correspondence with the at least two hydraulic cylinders (100), and each displacement sensor (32) is connected to the piston of the corresponding hydraulic cylinder (100).

4. The control system according to claim 3, characterized in that, The detection component (3) further includes at least two pressure sensors (33), which are arranged in a one-to-one correspondence with the at least two hydraulic cylinders (100). Each pressure sensor (33) is connected to the rodless chamber of the corresponding hydraulic cylinder (100). The electronic control component (4) is electrically connected to the at least two pressure sensors (33), and the electronic control component (4) is further configured to: control each of the control valve groups (2) to close if the difference between the first difference and the second difference is greater than a threshold. The first difference is the difference between the detection values ​​of the first pressure sensor and the second pressure sensor, and the second difference is the difference between the theoretical pressure of the rodless chamber of the first hydraulic cylinder and the theoretical pressure of the rodless chamber of the second hydraulic cylinder. The first pressure sensor is connected to the first hydraulic cylinder, and the second pressure sensor is connected to the second hydraulic cylinder. The first pressure sensor and the second pressure sensor are any two of the at least two pressure sensors (33).

5. The control system according to any one of claims 1-4, characterized in that, The pump set (1) includes an electric motor (11), a drive pump body (12), a variable cylinder (13), and a constant pressure control valve (14). The electric motor (11) is connected to the drive pump body (12), and the oil return port of the drive pump body (12) is connected to the rod chamber of the variable cylinder (13), the oil inlet of the constant pressure control valve (14), and the control oil port of the constant pressure control valve (14), respectively. The piston rod of the variable cylinder (13) is connected to the variable mechanism of the drive pump body (12) to reduce the displacement of the drive pump body (12) when the piston rod of the variable cylinder (13) extends, or to increase the displacement of the drive pump body (12) when the piston rod of the variable cylinder (13) retracts. The constant pressure control valve (14) is a hydraulic two-position three-way directional valve. The return port of the constant pressure control valve (14) is connected to the oil tank. The control port of the constant pressure control valve (14) is connected to its own inlet port. The working port of the constant pressure control valve (14) is connected to the rodless chamber of the variable cylinder (13).

6. The control system according to claim 5, characterized in that, The pump set (1) also includes a load-sensitive valve (15), a proportional flow valve (16), and a pilot proportional pressure reducing valve (17). The oil inlet of the load-sensitive valve (15) is connected to the oil return port of the drive pump body (12), the oil inlet of the constant pressure control valve (14), the first oil port of the proportional flow valve (16), and the oil inlet of the pilot proportional pressure reducing valve (17), respectively. The working oil port of the load-sensitive valve (15) is connected to the oil return port of the constant pressure control valve (14). The oil return port of the load-sensitive valve (15) is connected to the oil tank. The control oil port of the load-sensitive valve (15) is connected to its own oil inlet. The spring chamber of the load-sensitive valve (15) is connected to the second oil port of the proportional flow valve (16), the control oil port of the proportional flow valve (16) is connected to the working oil port of the pilot proportional pressure reducing valve (17), and the return oil port of the pilot proportional pressure reducing valve (17) is connected to the oil tank.

7. The control system according to claim 6, characterized in that, The pump set (1) also includes a main safety valve (18), the oil inlet of the main safety valve (18) is connected to its own control oil port and the spring cavity of the load sensitive valve (15), and the oil return port of the main safety valve (18) is connected to the oil tank. The spring chamber of the main safety valve (18) is connected to the oil inlet of the load-sensitive valve (15).

8. The control system according to claim 7, characterized in that, The pump unit (1) also includes a pilot proportional relief valve (19) and a pilot safety valve (110). The inlet of the pilot proportional relief valve (19) is connected to the inlet of the pilot safety valve (110), the spring chamber of the constant pressure control valve (14), and the spring chamber of the main safety valve (18), respectively. The return port of the pilot proportional relief valve (19) is connected to the oil tank. The control port of the pilot proportional relief valve (19) is connected to its own inlet. The return port of the pilot safety valve (110) is connected to the oil tank, and the control port of the pilot safety valve (110) is connected to its own inlet port.

9. The control system according to any one of claims 1-4 and 6-8, characterized in that, The control valve group (2) includes a proportional directional valve (21), a balance valve (22), and a pilot proportional directional valve (23). The inlet of the proportional directional valve (21) is connected to the return port of the pump group (1), the return port of the proportional directional valve (21) is connected to the oil tank, the first working port of the proportional directional valve (21) is connected to the first port of the balance valve (22), and the second working port of the proportional directional valve (21) is connected to the inlet of the pilot proportional directional valve (23) and the rod chamber of the hydraulic cylinder corresponding to the control valve group (2), respectively. The second oil port of the balance valve (22) is connected to the rodless chamber of the hydraulic cylinder corresponding to the control valve group (2), and the control oil port of the balance valve (22) is connected to the working oil port of the pilot proportional directional valve (23).

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