Load Simulation Loading System and Control Method Based on Engineering Machinery Power System

Abstract

This paper relates to a load simulation loading system and its control method based on a power system of engineering machinery, and pertains to the field of mechanical power system simulation technology. The load simulation loading system comprises a power system of engineering machinery, a load loading system, a vehicle control unit, and a host computer platform. The power system of the engineering machinery includes a first oil tank, a main pump, a pilot pump, a pilot control handle, a signal control valve, and a multi-way valve. The load loading system includes a three-position four-way directional valve connected to the multi-way valve, a proportional relief valve, a first proportional throttle valve, a second proportional throttle valve and a solenoid valve connected to the outlet of the proportional relief valve, a third proportional throttle valve connected between the second proportional throttle valve and the second oil tank, and a variable pump. The three-position four-way directional valve is configured to allow the inlet of the proportional relief valve to switch to one of the A and B ports of the multi-way valve, and the outlet to switch to the other of the A and B ports.

Description

Technical Field

[0001] This invention relates to the field of mechanical simulation technology, and more specifically, to a load simulation loading system and its control method based on the power system of engineering machinery. Background Technology

[0002] Currently, various technological approaches, such as hybrid power, pure electric drive, and distributed electro-hydraulic systems, are widely researched and applied to the power systems of construction machinery. During the product development phase, efficiently and accurately assessing the performance differences among various power systems is crucial. This not only helps save significant R&D costs but also significantly shortens the development cycle. Therefore, finding a method to efficiently evaluate the performance of the power systems of construction machinery before the machine leaves the factory has become a key competitive advantage for major companies.

[0003] Traditional performance evaluation of engineering machinery power systems typically relies on field testing of the entire machine under actual working conditions, measuring various performance indicators of the power system under load. However, this field testing method often requires significant human and material resources, and the testing process is complex and cumbersome. To achieve efficient performance evaluation of the entire machine's power system, simplifying load testing methods is essential, making hydraulic load simulation technology for engineering machinery power systems an important evaluation tool. A typical existing technical solution uses a proportional relief valve instead of the actual actuator cylinder, simulating load pressure by converting a preset load spectrum into the control current of the proportional relief valve and thus controlling its valve opening.

[0004] While proportional relief valve loading technology simplifies testing to some extent, this method has significant limitations. The rod-side and rodless-side chambers of hydraulic cylinders in construction machinery have structural area differences, resulting in unequal flow rates in the inlet and outlet chambers during oil flow. However, when using a proportional relief valve for load simulation, its inlet and outlet flow rates must be equal. This difference in flow characteristics causes a mismatch between the proportional relief valve's outlet flow rate and the actual return flow rate of the actuator cylinder during operation.

[0005] In actual operating conditions, when the return oil flow from the hydraulic cylinder enters the outlet of the multi-way valve, a specific back pressure is generated due to the throttling effect caused by the valve opening degree under different operating conditions. The mismatch between the outlet flow of the proportional relief valve and the actual return oil flow causes the back pressure generated by the system during simulation to be inconsistent with the actual operating conditions.

[0006] Furthermore, for large construction machinery, the return oil flow from the actuator cylinders during operation can have additional effects on the system, such as flow regeneration and differential drive effects. Existing technologies cannot accurately match these effects. This flow mismatch problem severely impacts the accuracy of load simulation, resulting in poor performance evaluation of the construction machinery's power system. Summary of the Invention

[0007] This invention provides a load simulation loading system and its control method based on the power system of engineering machinery, aiming to improve at least one of the above-mentioned technical problems.

[0008] In a first aspect, to solve the above-mentioned technical problems, the present invention provides a load simulation loading system based on an engineering machinery power system, which includes an engineering machinery power system, a load loading system, a vehicle control unit connected to the load loading system, and a host computer platform connected to the vehicle control unit.

[0009] The power system of the engineering machinery includes a main pump and a pilot pump connected to a first oil tank, a pilot control handle connected to the pilot pump, a signal control valve connected to the pilot control handle, and a multi-way valve connected to the main pump and the signal control valve.

[0010] The load loading system includes a three-position four-way directional valve connected to the multi-way valve, a proportional relief valve connected to the three-position four-way directional valve, a first proportional throttle valve connected between the outlet of the proportional relief valve and the three-position four-way directional valve, a second proportional throttle valve and a solenoid valve connected to the outlet of the proportional relief valve, a third proportional throttle valve connected between the second proportional throttle valve and the second oil tank, and a variable pump connected between the solenoid valve and the second oil tank.

[0011] The three-position four-way directional valve is configured to allow the inlet of the proportional relief valve to be switched to one of the A and B ports of the multi-way valve, and the outlet to be switched to the other of the A and B ports.

[0012] Secondly, this application also provides a control method for a load simulation loading system based on an engineering machinery power system, which is used to control a load simulation loading system based on an engineering machinery power system as described in any paragraph of the first aspect. The closed-loop control method of the load simulation loading system when simulating the cylinder extension condition includes steps A1 to A10.

[0013] A1. The first drive motor drives the main pump and pilot pump to draw oil from the first oil tank and outputs oil to the multi-way valve and pilot control handle respectively.

[0014] A2. The driver outputs pilot control fluid to the signal control valve by operating the pilot control handle.

[0015] A3. The signal control valve outputs a corresponding action control flow signal to the multi-way valve based on the input flow of the pilot control handle, so as to drive the oil to be output from the A port of the multi-way valve.

[0016] A4. The oil output from the multi-way valve reaches the three-position four-way directional valve through the first pressure sensor. At this time, the vehicle control unit sends a control electrical signal to drive the three-position four-way directional valve to work in the left position, so that the oil reaches the inlet of the proportional relief valve through the three-position four-way directional valve.

[0017] A5. The vehicle control unit sends a control current signal for the load spectrum conversion of the construction machinery during on-site excavation to the proportional relief valve to control its valve core opening and adjust the inlet pressure of the proportional relief valve. The oil flows out from the outlet of the proportional relief valve, and then passes through the four-way valve to the first proportional throttle valve, the second proportional throttle valve, and the solenoid valve.

[0018] A6. The vehicle control unit sends a control electrical signal to drive the solenoid valve to operate in the right position and cut off the oil circuit between the variable pump and the proportional relief valve, the first proportional throttle valve, and the second proportional throttle valve.

[0019] A7. The vehicle control unit collects the first pressure value from the fourth pressure sensor between the second and third proportional throttle valves and the second pressure value from the third pressure sensor between the first proportional throttle valve and the three-position four-way directional valve. Then, using a proportional-integral-derivative (PID) algorithm, it calculates and corrects the error between the first and second pressure values ​​to adjust the control current of the third proportional throttle valve in real time. This further adjusts the throttle orifice area of ​​the third proportional throttle valve, ensuring that the pressure between the second and third proportional throttle valves is the same as the pressure between the three-position four-way directional valve and the first proportional throttle valve. Specifically, during error correction, the proportional component adjusts based on the current error, the integral component eliminates the system's steady-state error, and the derivative component predicts and corrects the error's trend.

[0020] A8. Based on the area ratio of the rodless chamber and the rod chamber of the simulated actuator cylinder, the vehicle control unit sends a control electrical signal to the first proportional throttle valve and the second proportional throttle valve to adjust the throttle orifice area of ​​the first proportional throttle valve and the second proportional throttle valve, thereby controlling the oil flow rate through the first proportional throttle valve and the second proportional throttle valve.

[0021] A9. After the oil is diverted, part of it passes through the third pressure sensor to the three-position four-way directional valve, and then through the second pressure sensor to the B port of the multi-way valve, flowing back to the first oil tank. The other part passes through the second proportional throttle valve and the third proportional throttle valve back to the second oil tank.

[0022] A10. During the control process, the vehicle control unit uses a proportional-integral-derivative algorithm to calculate and correct the error between the load spectrum pressure and the first pressure sensor data collected by the vehicle control unit. This correction is used to adjust the control current of the proportional relief valve in real time, further adjusting the valve core opening of the proportional relief valve so that the pressure at port A of the multi-way valve matches the target loading pressure. This completes the accurate simulation of load loading and matching of return oil flow for the power system of the construction machinery. Specifically, during error correction, the proportional component adjusts according to the current error, the integral component eliminates the steady-state error of the system, and the derivative component predicts and corrects the error trend.

[0023] By adopting the above technical solution, the present invention can achieve the following technical effects:

[0024] This invention discloses a load simulation loading system based on the power system of engineering machinery. This solution eliminates the influence of oil back pressure on the output port pressure of the multi-way valve of the engineering machinery during the hydraulic load simulation loading process using a proportional relief valve. Furthermore, it balances the oil flow rate. While simplifying the load simulation loading system, it completely replaces the actuator cylinder with a proportional relief valve, solving the problem of mismatch between the outlet flow rate of the proportional relief valve and the outlet flow rate of the actuator cylinder, and finally completes the load simulation loading of the power system of the engineering machinery. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the specific embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the load simulation loading system.

[0027] Figure 2 This is a schematic diagram of a load simulation system that simulates the extension of a hydraulic cylinder.

[0028] Figure 3 This is a schematic diagram of the load simulation system when the hydraulic cylinder retracts.

[0029] The diagram is labeled as follows: 1-Engineering machinery power system, 2-Load loading system, 3-Vehicle control unit, 4-Host computer platform, 11-Pilot control handle, 12-Signal control valve, 13-Multi-way valve, 14-First drive motor, 15-Main pump, 16-Pilot pump, 17-First oil tank, 21-Three-position four-way directional valve, 22-Proportional relief valve, 23-First pressure sensor, 24-Second pressure sensor, 25-Third pressure sensor, 26-Fourth pressure sensor, 27-First proportional throttle valve, 28-Second proportional throttle valve, 29-Third proportional throttle valve, 210-Second drive motor, 211-Solenoid valve, 212-Variable pump, 213-Second oil tank, 214-Four-way valve. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0031] Example 1, by Figures 1 to 3 As shown, this embodiment of the invention provides a load simulation loading system based on an engineering machinery power system 1, comprising an engineering machinery power system 1, a load loading system 2, a vehicle control unit 3 connected to the load loading system 2, and a host computer platform 4 connected to the vehicle control unit 3.

[0032] The engineering machinery power system 1 includes a main pump 15 and a pilot pump 16 connected to a first oil tank 17, a pilot control handle 11 connected to the pilot pump 16, a signal control valve 12 connected to the pilot control handle 11, and a multi-way valve 13 connected to the main pump 15 and the signal control valve 12.

[0033] The load loading system 2 includes a three-position four-way directional valve 21 connected to the multi-way valve 13, a proportional relief valve 22 connected to the three-position four-way directional valve 21, a first proportional throttle valve 27 connected between the outlet of the proportional relief valve 22 and the three-position four-way directional valve 21, a second proportional throttle valve 28 connected to the outlet of the proportional relief valve 22 and a solenoid valve 211, a third proportional throttle valve 29 connected between the second proportional throttle valve 28 and the second oil tank 213, and a variable pump 212 connected between the solenoid valve 211 and the second oil tank 213.

[0034] The three-position four-way directional valve 21 is configured to allow the inlet of the proportional relief valve 22 to be switched to one of the A and B ports of the multi-way valve 13, and the outlet to be switched to the other of the A and B ports.

[0035] Specifically, in this embodiment, the control of both the relief valve and the throttle valve in the engineering machinery load simulation loading system based on the proportional relief valve 22 is electronic. The proportional relief valve 22 has a unidirectional conduction characteristic. In this embodiment, the switching of the oil outlet and return ports is achieved by controlling the three-position four-way directional valve 21 to match the multi-way valve 13.

[0036] It is understandable that the rod-side and rodless-side chambers of the hydraulic cylinder have different areas, resulting in different flow rates in the two chambers during hydraulic rod extension and retraction. For example, when the actuator cylinder's inlet chamber is the rodless-side chamber and the outlet chamber is the rod-side chamber, the actual outlet flow rate of the proportional relief valve 22 is greater than the actual outlet flow rate of the actuator cylinder.

[0037] Hydraulic load simulation systems typically convert a preset load spectrum into a corresponding proportional relief valve 22. The control current of the proportional relief valve 22 drives the valve core opening to control the valve inlet pressure, thus achieving loading. However, the inlet and outlet oil flow rates of the proportional relief valve 22 are the same. This difference in flow characteristics causes a mismatch between the outlet flow rate of the proportional relief valve 22 and the actual return oil flow rate during actuator cylinder operation.

[0038] This embodiment presents a load simulation loading system based on an engineering machinery power system 1. It utilizes a proportional relief valve 22 to replace the actuator and cylinder for load simulation loading, while also incorporating components such as a proportional throttle valve assembly, a solenoid valve 211, a three-position four-way directional valve 21, and a motor pump. By controlling the proportional throttle valve and the motor pump, the outlet flow of the proportional relief valve 22 is diverted and replenished to match the actual oil flow of the actuator cylinder. This allows for more accurate simulation of the actuator cylinder, demonstrating significant substantive features and substantial progress.

[0039] Based on the above embodiments, in an optional embodiment of the present invention, such as Figures 1 to 3 As shown, the load loading system 2 also includes a first pressure sensor 23 connected to port A of the multi-way valve 13, a second pressure sensor 24 connected to port B of the multi-way valve 13, a third pressure sensor 25 connected between the first proportional throttle valve 27 and the three-position four-way directional valve 21, and a fourth pressure sensor 26 connected between the second proportional throttle valve 28 and the third proportional throttle valve 29.

[0040] Specifically, the construction machinery power system 1 in this embodiment can be replaced with any construction machinery power system that uses hydraulic cylinders to drive actuators. The construction machinery power system 1 can be increased according to the number of hydraulic cylinders in the actual construction machinery power system 1; this embodiment only shows a single case. In this embodiment, the construction machinery power system 1 provides hydraulic flow to the load loading system 2.

[0041] When the power system 1 of the construction machinery is operating, the first drive motor 14 drives the main pump 15 and the pilot pump 16 to draw oil from the first oil tank 17 and output the system drive flow and system control flow respectively. The operator operates the pilot control handle 11 to output the pilot control flow to the signal control valve 12. The signal control valve 12 outputs a corresponding action control flow signal according to the input flow of the pilot control handle 11, which is sent to the multi-way valve 13. The multi-way valve 13 outputs the drive flow to the load loading system 2.

[0042] At this time, the first pressure sensor 23 and the second pressure sensor 24 in the load loading system 2 are used to detect the pressure between the multi-way valve 13 and the three-position four-way directional valve 21. The third pressure sensor 25 is used to detect the pressure between the first proportional throttle valve 27 and the three-position four-way directional valve 21. The fourth pressure sensor 26 is used to detect the pressure between the second proportional throttle valve 28 and the third proportional throttle valve 29. The three-position four-way directional valve 21 is used to ensure that when the output port of the multi-way valve 13 switches, the output drive flow always leads to the inlet of the proportional relief valve 22. The proportional relief valve 22 is used to apply load pressure to the engineering machinery power system 1. The first proportional throttle valve 27, the second proportional throttle valve 28, and the third proportional throttle valve 29 are used to adjust the flow rate between the outlet of the proportional relief valve 22 and the return port of the multi-way valve 13. The solenoid valve 211 is used to cut off the oil passage between the proportional relief valve 22 and the variable pump 212. The second oil tank 213 provides oil to the variable pump 212. The second drive motor 210 is used to drive the variable pump 212 to output flow.

[0043] Preferably, the multi-way valve 13 is provided with a control port, an oil inlet, an oil outlet, an A port, and a B port. The control port is configured to control the oil inlet to switch between being connected to one of the A port and the B port, and simultaneously control the oil outlet to switch between being connected to the other of the A port and the B port (i.e., the port not connected to the oil inlet). The control port is connected to the signal control valve 12. The oil inlet is connected to the main pump 15. The oil outlet is connected to the oil tank.

[0044] A hydraulic pipeline connection scheme for a load simulation loading system based on an engineering machinery power system 1 according to an embodiment of the present invention is as follows: The main pump 15 and the pilot pump 16 are connected to the first oil tank 17 via hydraulic pipes to draw oil. The main pump 15 is connected to the multi-way valve 13 via a pipeline to supply oil to the multi-way valve 13. The pilot pump 16 is connected to the pilot control handle 11 via a pipeline to supply oil to the pilot control handle 11. The pilot control handle 11 is connected to the signal control valve 12 via a pipeline. The signal control valve 12 is connected to the multi-way valve 13 via a pipeline. The signal control valve 12 provides secondary pilot pressure to control the opening degree of each valve port inside the multi-way valve 13, and to control the switching of the oil inlet to one of the A oil port and the B oil port.

[0045] The first pressure sensor 23 is connected via a tee to line A between the multi-way valve 13 and the three-position four-way directional valve 21. The second pressure sensor 24 is connected via a tee to line B between the multi-way valve 13 and the three-position four-way directional valve 21. The third pressure sensor 25 is connected to the line between the three-position four-way directional valve 21 and the first proportional throttle valve 27. The fourth pressure sensor 26 is connected to the line between the second proportional throttle valve 28 and the third proportional throttle valve 29.

[0046] Two ports on one side of the three-position four-way directional valve 21 are connected to the A port and B port of the multi-way valve 13, respectively, and two ports on the other side are connected to the inlet of the proportional relief valve 22 and the pipeline of the first proportional throttle valve 27, respectively.

[0047] The outlet of the proportional relief valve 22 is connected via a four-way valve 214 to the first proportional throttle valve 27, the second proportional throttle valve 28, and the solenoid valve 211. The second proportional throttle valve 28 is connected to the third proportional throttle valve 29, and the solenoid valve 211 is connected to the outlet of the variable pump 212. The low-pressure outlet of the third proportional throttle valve 29 is connected to the suction port of the variable pump 212 and the second oil tank 213. It should be noted that the first oil tank 17 and the second oil tank 213 can be the same oil tank or two independent oil tanks; both of these solutions fall within the scope of protection of this invention.

[0048] An electrical circuit connection scheme for a load simulation loading system based on a power system 1 of an engineering machinery according to an embodiment of the present invention is as follows: the vehicle control unit 3 is electrically connected to the first pressure sensor 23, the second pressure sensor 24, the third pressure sensor 25, and the fourth pressure sensor 26, so as to collect the electrical signal output of each sensor through the analog signal receiving port of the vehicle control unit 3.

[0049] The vehicle control unit 3 is electrically connected to the proportional overflow valve 22, the first proportional throttle valve 27, the second proportional throttle valve 28, and the third proportional throttle valve 29, so as to control the throttle orifice area of ​​the proportional overflow valve 22, the first proportional throttle valve 27, the second proportional throttle valve 28, and the third proportional throttle valve 29 by sending a control current signal through the PWM generation port on the vehicle control unit 3.

[0050] The vehicle control unit 3 is electrically connected to the electromagnets of the three-position four-way directional valve 21 and the solenoid valve 211. The vehicle control unit 3 sends electrical signals to energize the electromagnets of the three-position four-way directional valve 21 and the solenoid valve 211, thereby causing the valve cores to switch directions.

[0051] Preferred, such as Figures 1 to 3As shown, the engineering machinery power system 1 further includes a first drive motor 14 coupled to the main pump 15. The load loading system 2 includes a second drive motor 210 coupled to the variable pump 212. Specifically, the first drive motor 14 is mechanically connected to the main pump 15 via a splined bushing, and the main pump 15 drives the pilot pump 16 to operate via gear transmission. The second drive motor 210 is mechanically connected to the variable pump 212 via a splined bushing.

[0052] In this embodiment, the vehicle control unit 3 is electrically connected to the enable signal receiving port of the second drive motor 210 and the variable mechanism control port of the variable pump 212. The vehicle control unit 3 drives the motor pump to operate by sending control electrical signals to the enable signal receiving port of the second drive motor 210 and the variable mechanism control port of the variable pump 212. Since the power supply method of the drive motor does not affect the system and algorithm functions described in this embodiment, the power supply connection between the first drive motor 14 and the second drive motor 210 is omitted in this embodiment.

[0053] Preferably, the vehicle control unit 3 and the host computer platform 4 communicate via Peak-CAN bus. The host computer platform 4 imports the written program into the vehicle control unit 3 and monitors the changes in various parameters collected by the controller in real time.

[0054] The vehicle control unit 3 and the host computer platform 4 interact via CAN communication. The host computer platform 4 writes control programs and imports pre-set load spectra into the vehicle control unit 3. The vehicle control unit 3 receives analog inputs from various sensors and sends control electrical signals to various components. The vehicle control unit 3 receives current signals from the first pressure sensor 23, the second pressure sensor 24, the third pressure sensor 25, and the fourth pressure sensor 26, and converts them into actual pressure signals using formulas. The vehicle control unit 3 controls the electromagnet of the three-position four-way directional valve 21 to switch by sending electrical signals. The vehicle control unit 3 controls the electromagnets of the first proportional throttle valve 27, the second proportional throttle valve 28, and the third proportional throttle valve 29 to adjust their orifice areas by sending electrical signals of different magnitudes. The vehicle control unit 3 sends an electrical signal to the solenoid valve 211 to control the valve core position switching, and further controls the opening and closing of the oil circuit between the proportional relief valve 22 and the variable pump 212.

[0055] The following description uses one of the actuator cylinders of a certain construction machinery as an example to specifically describe the process of using a load simulation loading system based on the power system 1 of the construction machinery, as proposed in this embodiment, to replace the actuator cylinder on the construction machinery for load simulation loading of the power system 1. The actuator cylinder mainly includes an extension condition and a retraction condition, but is not limited to these two conditions.

[0056] In this embodiment, when the load simulation loading system simulates the extension condition of the actuator cylinder: oil flows out from port A of the multi-way valve 13 and returns from port B; the proportional relief valve 22 applies pressure to simulate the driving pressure of the rodless chamber of the engineering machinery cylinder. At this time, the outlet flow rate of the proportional relief valve 22 is greater than the actual oil flow rate of the cylinder, so the outlet flow rate of the proportional relief valve 22 needs to be diverted.

[0057] like Figure 2 As shown, the closed-loop control method of the load simulation loading system when the cylinder extends includes steps A1 to A10.

[0058] A1. The first drive motor 14 drives the main pump 15 and the pilot pump 16 to draw oil from the first oil tank 17, and outputs oil to the multi-way valve 13 and the pilot control handle 11 respectively.

[0059] A2. The driver outputs pilot control oil to signal control valve 12 by operating pilot control handle 11.

[0060] A3. The signal control valve 12 outputs a corresponding action control flow signal to the multi-way valve 13 according to the input flow of the pilot control handle 11, so as to drive the oil to be output from the A port of the multi-way valve 13.

[0061] A4. The oil output from the multi-way valve 13 passes through the first pressure sensor 23 and reaches the three-position four-way directional valve 21. At this time, the vehicle control unit 3 sends a control electrical signal to drive the three-position four-way directional valve 21 to work in the left position, so that the oil passes through the three-position four-way directional valve 21 and reaches the inlet of the proportional relief valve 22.

[0062] A5. The vehicle control unit 3 sends a control current signal for the load spectrum conversion of the construction machinery during on-site excavation to the proportional relief valve 22 to control its valve core opening and adjust the inlet pressure of the proportional relief valve 22. The oil flows out from the outlet of the proportional relief valve 22, and then passes through the four-way valve 214 to the first proportional throttle valve 27, the second proportional throttle valve 28, and the solenoid valve 211.

[0063] A6. The vehicle control unit 3 sends a control electrical signal to drive the solenoid valve 211 to operate in the right position and cut off the oil circuit between the variable pump 212 and the proportional relief valve 22, the first proportional throttle valve 27, and the second proportional throttle valve 28.

[0064] A7. The vehicle control unit 3 collects the first pressure value from the fourth pressure sensor 26 between the second proportional throttle valve 28 and the third proportional throttle valve 29, and the second pressure value from the third pressure sensor 25 between the first proportional throttle valve 27 and the three-position four-way directional valve 21. Then, using a proportional-integral-derivative algorithm, it calculates and corrects the error between the first and second pressure values ​​to adjust the control current of the third proportional throttle valve 29 in real time. This further adjusts the throttle orifice area of ​​the third proportional throttle valve 29, ensuring that the pressure between the second proportional throttle valve 28 and the third proportional throttle valve 29 is the same as the pressure between the three-position four-way directional valve 21 and the first proportional throttle valve 27. Specifically, during error correction, the proportional component adjusts according to the current error, the integral component eliminates the steady-state error of the system, and the derivative component predicts and corrects the error trend.

[0065] Specifically, by maintaining a balance between the fourth and third pressures, a pressure basis can be provided for the next step of controlling the flow split of the first proportional throttle valve 27 and the second proportional throttle valve 28, enabling precise control of the split flow rate. This has outstanding substantive features and significant progress.

[0066] A8. Based on the area ratio of the rodless chamber and the rod chamber of the simulated actuator cylinder, the vehicle control unit 3 sends a control electrical signal to the first proportional throttle valve 27 and the second proportional throttle valve 28 to adjust the throttle orifice area of ​​the first proportional throttle valve 27 and the second proportional throttle valve 28, thereby controlling the oil flow rate through the first proportional throttle valve 27 and the second proportional throttle valve 28.

[0067] The valve orifice throttling formula is:

[0068] .

[0069] Where, For oil flow rate, For flow coefficient, For the area of ​​the throttling orifice, For the pressure difference across the throttle valve, This refers to the density of the hydraulic oil.

[0070] According to the valve orifice throttling formula, when the flow coefficient and the pressure difference across the throttling valve remain constant, the flow rate through the throttling valve depends only on the orifice area. Therefore, step A8 specifically includes steps A81 to A82.

[0071] A81. Obtain the cross-sectional area of ​​the rodless cavity. Cross-sectional area of ​​the rod cavity .

[0072] A82. The vehicle control unit sends a control electrical signal to the first proportional throttle valve and the second proportional throttle valve to adjust the ratio of the throttle orifice area of ​​the first proportional throttle valve and the second proportional throttle valve to... This controls the ratio of oil flow through the first proportional throttle valve to that through the second proportional throttle valve.

[0073] Specifically, at this time, the pressure difference across the first proportional throttle valve 27 and the second proportional throttle valve 28 is the same. The flow rate through the first proportional throttle valve 27 and the second proportional throttle valve 28 is only affected by the orifice area of ​​the two valves. The vehicle control unit 3 can control the flow rate through the first proportional throttle valve 27 and the second proportional throttle valve 28 by adjusting the orifice area ratio of the two valves.

[0074] Assuming the area ratio of the rodless chamber to the rod chamber in the simulated actual hydraulic cylinder is 4:3, the vehicle control unit 3 sends a control signal to the first proportional throttle valve 27 and the second proportional throttle valve 28 to adjust the throttle orifice area of ​​the first proportional throttle valve 27 and the second proportional throttle valve 28 to 3:1, so that the flow rate through the first proportional throttle valve 27 is 3 / 4 of the inlet flow rate of the proportional relief valve 22, which satisfies the actual hydraulic cylinder's inlet and outlet flow rate relationship.

[0075] The control method of this embodiment controls the pressure difference across the proportional throttle valve of the proportional throttle valve group to remain constant and the throttle orifice area to adjust the throttle orifice area ratio of each proportional throttle valve, thereby achieving the diversion of the outlet flow of the proportional relief valve 22. This makes the flow of the outlet flow of the proportional relief valve 22 reaching the multi-way valve 13 equal to the flow of the actual actuator cylinder returning to the multi-way valve 13. This method can more realistically simulate the pressure situation of the actual actuator cylinder and has outstanding substantive features and significant progress.

[0076] A9. After the oil is diverted, part of it passes through the third pressure sensor 25 to the three-position four-way directional valve 21, and then through the second pressure sensor 24 to the B port of the multi-way valve 13, so as to flow back to the first oil tank 17. The other part passes through the second proportional throttle valve 28 and the third proportional throttle valve 29 to return to the second oil tank 213.

[0077] A10. During the control process, the vehicle control unit 3 uses a proportional-integral-derivative algorithm to calculate and correct the error between the load spectrum pressure and the first pressure sensor 23 collected by the vehicle control unit 3. This error is then used to adjust the control current of the proportional relief valve 22 in real time, further adjusting the valve core opening of the proportional relief valve 22 so that the pressure at port A of the multi-way valve 13 matches the target loading pressure. This completes the accurate simulation of load loading and matching of return oil flow for the power system of the engineering machinery. Specifically, during error correction, the proportional part adjusts according to the current error, the integral part eliminates the steady-state error of the system, and the derivative part predicts and corrects the error trend.

[0078] Specifically, when simulating the extended working condition where the inlet chamber of the actuator cylinder is a rod-type chamber and the outlet chamber is a rodless chamber, the actual outlet flow rate of the proportional relief valve 22 is less than the actual outlet flow rate of the actuator cylinder. The load simulation loading system of this embodiment replenishes the outlet flow rate of the proportional relief valve 22 by controlling the coordinated operation of the throttle valve group, solenoid valve 211, and motor pump. This ensures that the flow rate from the outlet of the proportional relief valve 22 to the multi-way valve 13 matches the flow rate from the actuator cylinder to the multi-way valve 13, achieving precise load simulation loading of the engineering machinery power system 1, representing a significant improvement.

[0079] This control method achieves precise diversion of the outlet flow of the proportional relief valve 22. Simultaneously, this embodiment addresses the impact of additional pressure caused by the complex hydraulic system on the output port pressure of the multi-way valve 13 by employing a proportional-integral-derivative algorithm in the vehicle control unit 3 to perform closed-loop control of the output port pressure of the multi-way valve 13.

[0080] In this embodiment, when the load simulation loading system simulates the retraction of the actuator cylinder: oil flows out from port B of the multi-way valve 13 and returns from port A; the proportional relief valve 22 applies pressure to simulate the rod-side drive pressure of the engineering machinery cylinder. At this time, the outlet flow rate of the proportional relief valve 22 is less than the actual cylinder oil flow rate, requiring replenishment of oil to the outlet flow rate of the proportional relief valve 22.

[0081] like Figure 3 As shown, the closed-loop control method of the load simulation loading system when simulating the retraction of the hydraulic cylinder includes steps B1 to B10.

[0082] B1. The first drive motor 14 drives the main pump 15 and the pilot pump 16 to draw oil from the first oil tank 17 and output oil to the multi-way valve 13 and the pilot control handle 11 respectively.

[0083] B2. The driver outputs pilot control oil to signal control valve 12 by operating pilot control handle 11.

[0084] B3. The signal control valve 12 outputs a corresponding action control flow signal to the multi-way valve 13 according to the input flow of the pilot control handle 11, so as to drive the oil to be output from the B port of the multi-way valve 13.

[0085] B4. The oil output from the multi-way valve 13 passes through the second pressure sensor 24 and reaches the three-position four-way directional valve 21. At this time, the vehicle control unit 3 sends a control electrical signal to drive the three-position four-way directional valve 21 to work in the right position. Then the oil passes through the three-position four-way directional valve 21 and reaches the inlet of the proportional relief valve 22.

[0086] B5. The vehicle control unit 3 sends a control current signal for the load spectrum conversion of the construction machinery during on-site excavation to the proportional relief valve 22 to control its valve core opening and adjust the inlet pressure of the proportional relief valve 22. The oil flows out from the outlet of the proportional relief valve 22, and then passes through the four-way valve 214 to the first proportional throttle valve 27, the second proportional throttle valve 28, and the solenoid valve 211.

[0087] B6. The vehicle control unit 3 sends a control electrical signal to drive the solenoid valve 211 to work in the left position, thereby connecting the oil circuit between the variable pump 212 and the proportional relief valve 22, the first proportional throttle valve 27, and the second proportional throttle valve 28.

[0088] B7. The vehicle control unit 3 sends control electrical signals to the first proportional throttle valve 27 and the second proportional throttle valve 28, causing the first proportional throttle valve 27 to be fully open and the second proportional throttle valve 28 to be completely closed.

[0089] B8. The vehicle control unit 3 sends a control electrical signal to the variable mechanism of the second drive motor 210 and the variable pump 212 based on the area ratio of the rodless chamber and the rod chamber of the simulated actuator cylinder (i.e., calculate the flow difference between the rod chamber and the rodless chamber of the actual cylinder), so as to drive the variable mechanism to output hydraulic oil to replenish and merge the flow of the proportional relief valve 22.

[0090] B9. After merging, the oil passes through the first proportional throttle valve 27 and the three-position four-way directional valve 21 to reach the A port of the multi-way valve 13, so as to flow back to the first oil tank 17.

[0091] B10. During the control process, the vehicle control unit 3 uses a proportional-integral-derivative algorithm to calculate and correct the error between the load spectrum pressure and the second pressure sensor 24 collected by the vehicle control unit 3. This correction is used to adjust the control current of the proportional relief valve 22 in real time, further adjusting the valve core opening of the proportional relief valve 22 so that the pressure at port B of the multi-way valve 13 matches the target loading pressure. This achieves accurate simulation of the load on the power system of the construction machinery and matches the return oil flow. Specifically, during error correction, the proportional part adjusts according to the current error, the integral part eliminates the steady-state error of the system, and the derivative part predicts and corrects the error trend.

[0092] In this embodiment, in order to address the impact of additional pressure caused by the complex hydraulic system on the output port pressure of the multi-way valve 13, a proportional-integral-derivative algorithm is additionally used in the vehicle control unit 3 to perform closed-loop control on the output port pressure of the multi-way valve 13.

[0093] The control method in this embodiment is adaptable to the actuator cylinder parameters of various types of engineering machinery. Through the coordinated control of the three-position four-way directional valve 21, the proportional relief valve 22, the proportional throttle valve, the solenoid valve 211, and the motor pump, the flow rate at the outlet of the proportional relief valve 22 is diverted or replenished, achieving precise control of the flow rate from the outlet of the proportional relief valve 22 to the input port of the multi-way valve 13. Furthermore, a proportional-integral-derivative algorithm is used for closed-loop control of the pressure at the output port of the multi-way valve 13, avoiding error fluctuations caused by the complex hydraulic system and achieving precise control.

[0094] This invention proposes a load simulation loading system and closed-loop control method based on a proportional relief valve 22, a proportional throttle valve, a solenoid valve 211, and a motor pump. By controlling the pressure difference across the throttle valve and the orifice area of ​​the throttle valve to maintain a constant pressure difference, the outlet flow of the proportional relief valve 22 is diverted. By controlling the coordinated operation of the motor pump, throttle valve, and solenoid valve 211, oil is replenished to the outlet flow of the proportional relief valve 22, thus achieving accurate load simulation loading of the power system 1 of the construction machinery and simplifying the size of the load simulation loading system. Simultaneously, it solves the problem of mismatch between the inlet and outlet flow of the proportional relief valve 22 and the actual inlet and outlet flow of the hydraulic cylinder in the construction machinery, further improving the load simulation loading of the hydraulic outlet pressure of the multi-way valve 13 in the construction machinery.

[0095] The load simulation loading system solves the problem of mismatch between the return oil flow rate and the actual oil cylinder return flow rate when using the proportional relief valve 22 for pressure load simulation in traditional engineering machinery by introducing a proportional throttle valve, a proportional relief valve 22, a solenoid valve 211, and a motor pump assembly. The closed-loop control method uses a proportional-integral-derivative algorithm to perform closed-loop control on the proportional throttle valve and the proportional relief valve 22, which greatly improves the system's response speed and accuracy.

[0096] Example 2: The second embodiment of the present invention provides a control method for a load simulation loading system based on an engineering machinery power system, which is used to control the load simulation loading system based on an engineering machinery power system described in any paragraph of Example 1.

[0097] The closed-loop control method for the load simulation loading system under simulated cylinder extension conditions includes steps A1 to A10.

[0098] A1. The first drive motor drives the main pump and pilot pump to draw oil from the first oil tank and outputs oil to the multi-way valve and pilot control handle respectively.

[0099] A2. The driver outputs pilot control fluid to the signal control valve by operating the pilot control handle.

[0100] A3. The signal control valve outputs a corresponding action control flow signal to the multi-way valve based on the input flow of the pilot control handle, so as to drive the oil to be output from the A port of the multi-way valve.

[0101] A4. The oil output from the multi-way valve reaches the three-position four-way directional valve through the first pressure sensor. At this time, the vehicle control unit sends a control electrical signal to drive the three-position four-way directional valve to work in the left position, so that the oil reaches the inlet of the proportional relief valve through the three-position four-way directional valve.

[0102] A5. The vehicle control unit sends a control current signal for the load spectrum conversion of the construction machinery during on-site excavation to the proportional relief valve to control its valve core opening and adjust the inlet pressure of the proportional relief valve. The oil flows out from the outlet of the proportional relief valve, and then passes through the four-way valve to the first proportional throttle valve, the second proportional throttle valve, and the solenoid valve.

[0103] A6. The vehicle control unit sends a control electrical signal to drive the solenoid valve to operate in the right position and cut off the oil circuit between the variable pump and the proportional relief valve, the first proportional throttle valve, and the second proportional throttle valve.

[0104] A7. The vehicle control unit collects the first pressure value from the fourth pressure sensor between the second and third proportional throttle valves and the second pressure value from the third pressure sensor between the first proportional throttle valve and the three-position four-way directional valve. Then, using a proportional-integral-derivative (PID) algorithm, it calculates and corrects the error between the first and second pressure values ​​to adjust the control current of the third proportional throttle valve in real time. This further adjusts the throttle orifice area of ​​the third proportional throttle valve, ensuring that the pressure between the second and third proportional throttle valves is the same as the pressure between the three-position four-way directional valve and the first proportional throttle valve. Specifically, during error correction, the proportional component adjusts based on the current error, the integral component eliminates the system's steady-state error, and the derivative component predicts and corrects the error's trend.

[0105] A8. Based on the area ratio of the rodless chamber and the rod chamber of the simulated actuator cylinder, the vehicle control unit sends a control electrical signal to the first proportional throttle valve and the second proportional throttle valve to adjust the throttle orifice area of ​​the first proportional throttle valve and the second proportional throttle valve, thereby controlling the oil flow rate through the first proportional throttle valve and the second proportional throttle valve.

[0106] A9. After the oil is diverted, part of it passes through the third pressure sensor to the three-position four-way directional valve, and then through the second pressure sensor to the B port of the multi-way valve, flowing back to the first oil tank. The other part passes through the second proportional throttle valve and the third proportional throttle valve back to the second oil tank.

[0107] A10. During the control process, the vehicle control unit uses a proportional-integral-derivative algorithm to calculate and correct the error between the load spectrum pressure and the first pressure sensor data collected by the vehicle control unit. This error is then used to adjust the control current of the proportional relief valve in real time, further adjusting the valve core opening of the proportional relief valve so that the pressure at port A of the multi-way valve matches the target loading pressure. This achieves accurate simulation of the load on the engineering machinery's power system and matches the return oil flow. Specifically, during error correction, the proportional component adjusts based on the current error, the integral component eliminates the system's steady-state error, and the derivative component predicts and corrects the error's changing trend.

[0108] Based on the above embodiments, in an optional embodiment of the present invention, when simulating the retraction of the hydraulic cylinder, the closed-loop control method of the load simulation loading system includes steps B1 to B10.

[0109] B1. The first drive motor drives the main pump and pilot pump to draw oil from the first oil tank and output oil to the multi-way valve and pilot control handle respectively.

[0110] B2. The driver outputs pilot control fluid to the signal control valve by operating the pilot control handle.

[0111] B3. The signal control valve outputs a corresponding action control flow signal to the multi-way valve based on the input flow of the pilot control handle, so as to drive the oil to be output from the B port of the multi-way valve.

[0112] B4. The oil output from the multi-way valve reaches the three-position four-way directional valve through the second pressure sensor. At this time, the vehicle control unit sends a control electrical signal to drive the three-position four-way directional valve to work in the right position. Then the oil reaches the inlet of the proportional relief valve through the three-position four-way directional valve.

[0113] B5. The vehicle control unit sends a control current signal for the load spectrum conversion of the construction machinery during on-site excavation to the proportional relief valve to control its valve core opening and set the inlet pressure of the proportional relief valve. The oil flows out from the outlet of the proportional relief valve, and then passes through the four-way valve to the first proportional throttle valve, the second proportional throttle valve, and the solenoid valve.

[0114] B6. The vehicle control unit sends a control electrical signal to drive the solenoid valve to work in the left position, connecting the oil circuit between the variable pump and the proportional relief valve, the first proportional throttle valve, and the second proportional throttle valve.

[0115] B7. The vehicle control unit sends control electrical signals to the first proportional throttle valve and the second proportional throttle valve, causing the first proportional throttle valve to fully open and the second proportional throttle valve to fully close.

[0116] B8. The vehicle control unit sends a control electrical signal to the variable mechanism of the second drive motor and the variable pump based on the area ratio of the rodless chamber and the rod chamber of the simulated actuator cylinder, so as to drive the variable mechanism to output hydraulic oil to replenish and merge the flow of the proportional relief valve outlet.

[0117] B9. After merging, the oil passes through the first proportional throttle valve and the three-position four-way directional valve to reach port A of the multi-way valve, so as to flow back to the first oil tank.

[0118] B10. During the control process, the vehicle control unit uses a proportional-integral-derivative algorithm to calculate and correct the error between the load spectrum pressure and the second pressure sensor data collected by the vehicle control unit. This correction is used to adjust the control current of the proportional relief valve in real time, further adjusting the valve core opening of the proportional relief valve so that the pressure at port B of the multi-way valve matches the target loading pressure. This achieves accurate simulation of the load on the engineering machinery's power system and matches the return oil flow. Specifically, during error correction, the proportional component adjusts based on the current error, the integral component eliminates the system's steady-state error, and the derivative component predicts and corrects the error's changing trend.

[0119] Obviously, the above detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to describe preferred embodiments, not all embodiments, and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Based on the embodiments of the invention, any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art to all other embodiments obtained without inventive effort are within the scope of protection of the invention.

Claims

1. A load simulation loading system based on the power system of engineering machinery, characterized in that, It includes an engineering machinery power system, a load loading system, a vehicle control unit that is connected to the load loading system, and a host computer platform that is connected to the vehicle control unit. The power system of the engineering machinery includes a main pump and a pilot pump connected to a first oil tank, a pilot control handle connected to the pilot pump, a signal control valve connected to the pilot control handle, and a multi-way valve connected to the main pump and the signal control valve. The load loading system includes a three-position four-way directional valve connected to the multi-way valve, a proportional relief valve connected to the three-position four-way directional valve, a first proportional throttle valve connected between the outlet of the proportional relief valve and the three-position four-way directional valve, a second proportional throttle valve and a solenoid valve connected to the outlet of the proportional relief valve, a third proportional throttle valve connected between the second proportional throttle valve and the second oil tank, and a variable pump connected between the solenoid valve and the second oil tank. The three-position four-way directional valve is configured to allow the inlet of the proportional relief valve to be switched to one of the A and B ports of the multi-way valve, and the outlet to be switched to the other of the A and B ports. The load loading system further includes a first pressure sensor connected to port A of the multi-way valve, a second pressure sensor connected to port B of the multi-way valve, a third pressure sensor connected between the first proportional throttle valve and the three-position four-way directional valve, and a fourth pressure sensor connected between the second proportional throttle valve and the third proportional throttle valve. The engineering machinery power system also includes a first drive motor connected to the main pump; the load loading system includes a second drive motor connected to the variable pump; The vehicle control unit is electrically connected to the enable signal receiving port of the second drive motor and the variable mechanism control port of the variable pump; the vehicle control unit drives the motor pump to work by sending control electrical signals to the enable signal receiving port of the second drive motor and the variable mechanism control port of the variable pump. By coordinating the control of the three-position four-way directional valve, the proportional relief valve, the proportional throttle valve, the solenoid valve and the motor pump, the outlet flow of the proportional relief valve is diverted or replenished; and the output port pressure of the multi-way valve is controlled in a closed loop using a proportional-integral-derivative algorithm.

2. The load simulation loading system based on the power system of engineering machinery according to claim 1, characterized in that, The multi-way valve is provided with a control port, an oil inlet, an oil outlet, an A port, and a B port; the control port is configured to control the oil inlet to switch between being connected to one of the A port and the B port, and simultaneously control the oil outlet to switch between being connected to the other of the A port and the B port; the control port is connected to the signal control valve; the oil inlet is connected to the main pump; and the oil outlet is connected to the oil tank.

3. The load simulation loading system based on the power system of engineering machinery according to claim 1, characterized in that, The vehicle control unit is electrically connected to the first pressure sensor, the second pressure sensor, the third pressure sensor, and the fourth pressure sensor to acquire the electrical signal output of each sensor through the analog signal receiving port of the vehicle control unit. The vehicle control unit is electrically connected to the proportional overflow valve, the first proportional throttle valve, the second proportional throttle valve, and the third proportional throttle valve, so as to control the throttle orifice area of ​​the proportional overflow valve, the first proportional throttle valve, the second proportional throttle valve, and the third proportional throttle valve by sending a control current signal through the PWM generator port on the vehicle control unit. The vehicle control unit is electrically connected to the electromagnet of the three-position four-way reversing valve and the solenoid valve. The vehicle control unit sends electrical signals to energize the electromagnets of the three-position four-way reversing valve and the solenoid valve respectively, thereby causing the valve core to switch.

4. The load simulation loading system based on the power system of engineering machinery according to claim 3, characterized in that, When the cylinder of the actuator is extended: oil is discharged from port A of the multi-way valve and oil is returned from port B. The proportional relief valve applies pressure to simulate the driving pressure of the rodless chamber of the hydraulic cylinder in engineering machinery. At this time, the outlet flow rate of the proportional relief valve is greater than the actual oil output flow rate of the cylinder, and the outlet flow rate of the proportional relief valve needs to be diverted. The closed-loop control method for the load simulation loading system under the simulated cylinder extension condition is as follows: The first drive motor drives the main pump and pilot pump to draw oil from the first oil tank and outputs oil to the multi-way valve and pilot control handle respectively. The driver outputs pilot control fluid to the signal control valve by operating the pilot control lever; The signal control valve outputs a corresponding action control flow signal to the multi-way valve based on the input flow of the pilot control handle, so as to drive the oil to be output from the A port of the multi-way valve; The oil output from the multi-way valve reaches the three-position four-way directional valve through the first pressure sensor. At this time, the vehicle control unit sends a control electrical signal to drive the three-position four-way directional valve to work in the left position, so that the oil reaches the inlet of the proportional relief valve through the three-position four-way directional valve. The vehicle control unit sends a control current signal for load spectrum conversion of the construction machinery to the proportional relief valve to control its valve core opening and set the inlet pressure of the proportional relief valve; the oil flows out from the outlet of the proportional relief valve and then passes through the four-way valve to the first proportional throttle valve, the second proportional throttle valve, and the solenoid valve. The vehicle control unit sends a control electrical signal to drive the solenoid valve to operate in the right position and cut off the oil circuit between the variable pump and the proportional relief valve, the first proportional throttle valve, and the second proportional throttle valve; The vehicle control unit collects the first pressure value from the fourth pressure sensor between the second and third proportional throttle valves and the second pressure value from the third pressure sensor between the first proportional throttle valve and the three-position four-way directional valve. Then, it uses a proportional-integral-derivative algorithm to calculate and correct the error between the first and second pressure values, thereby adjusting the control current of the third proportional throttle valve in real time. This further adjusts the throttle orifice area of ​​the third proportional throttle valve to make the pressure between the second and third proportional throttle valves the same as the pressure between the three-position four-way directional valve and the first proportional throttle valve. During error correction, the proportional part adjusts according to the current error, the integral part eliminates the steady-state error of the system, and the derivative part predicts and corrects the error trend. Based on the area ratio of the rodless chamber and the rod chamber of the simulated actuator cylinder, the vehicle control unit sends control electrical signals to the first proportional throttle valve and the second proportional throttle valve to adjust the throttle orifice area of ​​the first proportional throttle valve and the second proportional throttle valve, thereby controlling the oil flow through the first proportional throttle valve and the second proportional throttle valve. After being diverted, part of the oil passes through the third pressure sensor to the three-position four-way directional valve, and then through the second pressure sensor to the B port of the multi-way valve to flow back to the first oil tank; the other part passes through the second proportional throttle valve and the third proportional throttle valve back to the second oil tank. During the control process, the vehicle control unit uses a proportional-integral-derivative algorithm to calculate and correct the error between the load spectrum pressure and the first pressure sensor collected by the vehicle control unit. This error is then used to adjust the control current of the proportional relief valve in real time and further adjust the valve core opening of the proportional relief valve so that the pressure at port A of the multi-way valve matches the target loading pressure. This completes the accurate simulation of the load and matching of the return oil flow of the power system of the construction machinery. Specifically, during error correction, the proportional part is adjusted according to the current error, the integral part eliminates the steady-state error of the system, and the derivative part predicts the trend of error change and corrects it.

5. The load simulation loading system based on the power system of engineering machinery according to claim 4, characterized in that, Based on the simulated area ratio of the rodless chamber and the rod chamber of the actuator cylinder, the vehicle control unit sends control electrical signals to the first proportional throttle valve and the second proportional throttle valve to adjust the throttle orifice area of ​​the first and second proportional throttle valves, thereby controlling the oil flow rate through the first and second proportional throttle valves. Specifically, this includes: The valve orifice throttling formula is: ； Where, For oil flow rate, For flow coefficient, For the area of ​​the throttling orifice, For the pressure difference across the throttle valve, The density of the hydraulic oil; According to the valve orifice throttling formula, when the flow coefficient and the pressure difference across the throttling valve remain constant, the flow rate through the throttling valve is only related to the orifice area. Obtain the cross-sectional area of ​​the rodless cavity Cross-sectional area of ​​the rod cavity ; The vehicle control unit sends control electrical signals to the first proportional throttle valve and the second proportional throttle valve to adjust the ratio of the throttle orifice areas of the first proportional throttle valve and the second proportional throttle valve to a certain value. This controls the ratio of oil flow through the first proportional throttle valve to that through the second proportional throttle valve.

6. The load simulation loading system based on the power system of engineering machinery according to claim 3, characterized in that, When the hydraulic cylinder of the actuator retracts: oil is discharged from port B of the multi-way valve and oil is returned from port A. The proportional relief valve applies pressure to simulate the driving pressure of the rod chamber of the hydraulic cylinder in engineering machinery. At this time, the outlet flow rate of the proportional relief valve is less than the actual oil flow rate of the cylinder, and oil needs to be added to the outlet flow rate of the proportional relief valve. When simulating the retraction of the hydraulic cylinder, the closed-loop control method of the load simulation loading system is as follows: The first drive motor drives the main pump and pilot pump to draw oil from the first oil tank and outputs oil to the multi-way valve and pilot control handle respectively. The driver outputs pilot control fluid to the signal control valve by operating the pilot control lever; The signal control valve outputs a corresponding action control flow signal to the multi-way valve based on the input flow of the pilot control handle, so as to drive the oil to be output from the B port of the multi-way valve; The oil output from the multi-way valve reaches the three-position four-way directional valve through the second pressure sensor. At this time, the vehicle control unit sends a control electrical signal to drive the three-position four-way directional valve to work in the right position. Then the oil reaches the inlet of the proportional relief valve through the three-position four-way directional valve. The vehicle control unit sends a control current signal for load spectrum conversion of the construction machinery to the proportional relief valve to control its valve core opening and set the inlet pressure of the proportional relief valve; the oil flows out from the outlet of the proportional relief valve and then passes through the four-way valve to the first proportional throttle valve, the second proportional throttle valve, and the solenoid valve. The vehicle control unit sends a control electrical signal to drive the solenoid valve to work in the left position, thus connecting the oil circuit between the variable pump and the proportional relief valve, the first proportional throttle valve, and the second proportional throttle valve; The vehicle control unit sends control electrical signals to the first proportional throttle valve and the second proportional throttle valve, causing the first proportional throttle valve to fully open and the second proportional throttle valve to completely close. The vehicle control unit sends control electrical signals to the variable mechanism of the second drive motor and the variable pump based on the area ratio of the rodless chamber and the rod chamber of the simulated actuator cylinder, so as to drive the variable mechanism to output hydraulic oil to replenish and merge the flow of the proportional relief valve outlet flow. After merging, the oil passes through the first proportional throttle valve and the three-position four-way directional valve to reach port A of the multi-way valve, so as to flow back to the first oil tank. During the control process, the vehicle control unit uses a proportional-integral-derivative algorithm to calculate and correct the error between the load spectrum pressure and the second pressure sensor collected by the vehicle control unit. This error is then used to adjust the control current of the proportional relief valve in real time and further adjust the valve core opening of the proportional relief valve so that the pressure at port B of the multi-way valve matches the target loading pressure. This achieves accurate simulation of the load on the power system of the construction machinery and matches the return oil flow. Specifically, during error correction, the proportional part is adjusted according to the current error, the integral part eliminates the steady-state error of the system, and the derivative part predicts the trend of error change and corrects it.

7. A control method for a load simulation loading system based on the power system of engineering machinery, characterized in that, Used to control a load simulation loading system based on an engineering machinery power system as described in any one of claims 1 to 6; The closed-loop control method for the load simulation loading system under the simulated cylinder extension condition is as follows: The first drive motor drives the main pump and pilot pump to draw oil from the first oil tank and outputs oil to the multi-way valve and pilot control handle respectively. The driver outputs pilot control fluid to the signal control valve by operating the pilot control lever; The signal control valve outputs a corresponding action control flow signal to the multi-way valve based on the input flow of the pilot control handle, so as to drive the oil to be output from the A port of the multi-way valve; The oil output from the multi-way valve reaches the three-position four-way directional valve through the first pressure sensor. At this time, the vehicle control unit sends a control electrical signal to drive the three-position four-way directional valve to work in the left position, so that the oil reaches the inlet of the proportional relief valve through the three-position four-way directional valve. The vehicle control unit sends a control current signal for load spectrum conversion of the construction machinery to the proportional relief valve to control its valve core opening and set the inlet pressure of the proportional relief valve; the oil flows out from the outlet of the proportional relief valve and then passes through the four-way valve to the first proportional throttle valve, the second proportional throttle valve, and the solenoid valve. The vehicle control unit sends a control electrical signal to drive the solenoid valve to operate in the right position and cut off the oil circuit between the variable pump and the proportional relief valve, the first proportional throttle valve, and the second proportional throttle valve; The vehicle control unit collects the first pressure value from the fourth pressure sensor between the second and third proportional throttle valves and the second pressure value from the third pressure sensor between the first proportional throttle valve and the three-position four-way directional valve. Then, it uses a proportional-integral-derivative algorithm to calculate and correct the error between the first and second pressure values, thereby adjusting the control current of the third proportional throttle valve in real time. This further adjusts the throttle orifice area of ​​the third proportional throttle valve to make the pressure between the second and third proportional throttle valves the same as the pressure between the three-position four-way directional valve and the first proportional throttle valve. During error correction, the proportional part adjusts according to the current error, the integral part eliminates the steady-state error of the system, and the derivative part predicts and corrects the error trend. Based on the area ratio of the rodless chamber and the rod chamber of the simulated actuator cylinder, the vehicle control unit sends control electrical signals to the first proportional throttle valve and the second proportional throttle valve to adjust the throttle orifice area of ​​the first proportional throttle valve and the second proportional throttle valve, thereby controlling the oil flow through the first proportional throttle valve and the second proportional throttle valve. After being diverted, part of the oil passes through the third pressure sensor to the three-position four-way directional valve, and then through the second pressure sensor to the B port of the multi-way valve to flow back to the first oil tank; the other part passes through the second proportional throttle valve and the third proportional throttle valve back to the second oil tank. During the control process, the vehicle control unit uses a proportional-integral-derivative algorithm to calculate and correct the error between the load spectrum pressure and the first pressure sensor collected by the vehicle control unit. This error is then used to adjust the control current of the proportional relief valve in real time and further adjust the valve core opening of the proportional relief valve so that the pressure at port A of the multi-way valve matches the target loading pressure. This completes the accurate simulation of the load and matching of the return oil flow of the power system of the construction machinery. Specifically, during error correction, the proportional part is adjusted according to the current error, the integral part eliminates the steady-state error of the system, and the derivative part predicts the trend of error change and corrects it.

8. The control method for a load simulation loading system based on an engineering machinery power system according to claim 7, characterized in that, When simulating the retraction of the hydraulic cylinder, the closed-loop control method of the load simulation loading system is as follows: The first drive motor drives the main pump and pilot pump to draw oil from the first oil tank and outputs oil to the multi-way valve and pilot control handle respectively. The driver outputs pilot control fluid to the signal control valve by operating the pilot control lever; The signal control valve outputs a corresponding action control flow signal to the multi-way valve based on the input flow of the pilot control handle, so as to drive the oil to be output from the B port of the multi-way valve; The oil output from the multi-way valve reaches the three-position four-way directional valve through the second pressure sensor. At this time, the vehicle control unit sends a control electrical signal to drive the three-position four-way directional valve to work in the right position. Then the oil reaches the inlet of the proportional relief valve through the three-position four-way directional valve. The vehicle control unit sends a control current signal for load spectrum conversion of the construction machinery to the proportional relief valve to control its valve core opening and set the inlet pressure of the proportional relief valve; the oil flows out from the outlet of the proportional relief valve and then passes through the four-way valve to the first proportional throttle valve, the second proportional throttle valve, and the solenoid valve. The vehicle control unit sends a control electrical signal to drive the solenoid valve to work in the left position, thus connecting the oil circuit between the variable pump and the proportional relief valve, the first proportional throttle valve, and the second proportional throttle valve; The vehicle control unit sends control electrical signals to the first proportional throttle valve and the second proportional throttle valve, causing the first proportional throttle valve to fully open and the second proportional throttle valve to completely close. The vehicle control unit sends control electrical signals to the variable mechanism of the second drive motor and the variable pump based on the area ratio of the rodless chamber and the rod chamber of the simulated actuator cylinder, so as to drive the variable mechanism to output hydraulic oil to replenish and merge the flow of the proportional relief valve outlet flow. After merging, the oil passes through the first proportional throttle valve and the three-position four-way directional valve to reach port A of the multi-way valve, so as to flow back to the first oil tank. During the control process, the vehicle control unit uses a proportional-integral-derivative algorithm to calculate and correct the error between the load spectrum pressure and the second pressure sensor collected by the vehicle control unit. This error is then used to adjust the control current of the proportional relief valve in real time and further adjust the valve core opening of the proportional relief valve so that the pressure at port B of the multi-way valve matches the target loading pressure. This achieves accurate simulation of the load on the power system of the construction machinery and matches the return oil flow. Specifically, during error correction, the proportional part is adjusted according to the current error, the integral part eliminates the steady-state error of the system, and the derivative part predicts the trend of error change and corrects it.

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