Load simulation loading system based on engineering machinery power system and control method thereof

Abstract

The invention discloses a load simulation loading system based on an engineering mechanical power system and a control method thereof, and relates to the technical field of mechanical power system simulation. The load simulation loading system comprises an engineering machinery power system, a load loading system, a whole vehicle control unit and an upper computer platform. The engineering machinery power system comprises 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 comprises a three-position four-way reversing valve, a proportional overflow valve, a first proportional throttle valve, a second proportional throttle valve, an electromagnetic valve, a third proportional throttle valve and a variable pump, wherein the three-position four-way reversing valve, the proportional overflow valve and the first proportional throttle valve are connected to the multi-way valve, the second proportional throttle valve and the electromagnetic valve are connected to an outlet of the proportional overflow valve, and the third proportional throttle valve is connected between the second proportional throttle valve and the second oil tank. And the three-position four-way reversing valve is constructed to enable an inlet of the proportional overflow valve to be communicated with one of the oil port A and the oil port B of the multi-way valve in a switching manner, and an outlet of the proportional overflow valve to be communicated with the other one of the oil port A and the oil port B in a switching manner.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical simulation, and in particular to a load simulation loading system based on an engineering machinery power system and a control method thereof. Background Art

[0002] Currently, various technical approaches, including hybrid powertrains, pure electric drives, and distributed electro-hydraulic systems, are being widely researched and applied to construction machinery powertrains. Efficiently and accurately evaluating the performance differences between these various powertrains is crucial during the product development phase. This not only helps save significant R&D costs but also significantly shortens the development cycle. Therefore, finding a method to efficiently evaluate the powertrain performance of construction machinery before it leaves the factory has become a key competitive advantage for major companies.

[0003] Traditional performance evaluation of engineering machinery power systems usually relies on field testing of the entire machine under actual working conditions, and is achieved by measuring the various performance indicators of the entire machine power system under load. However, this field testing method often requires a large amount of manpower and material resources, and the testing process is complicated and tedious. In order to achieve efficient performance evaluation of the entire machine power system, simplifying the load testing method has become an inevitable requirement, and the hydraulic load simulation technology of the engineering machinery power system has thus become an important evaluation method. A typical existing technical solution is to use a proportional relief valve instead of the actual actuator cylinder, and to simulate the load pressure by converting the preset load spectrum into the control current of the proportional relief valve, and then controlling its valve opening.

[0004] While the proportional relief valve loading technique simplifies testing to some extent, it has significant limitations. The structural differences in area between the rod and rodless chambers of construction machinery actuator cylinders result in unequal flow rates between the inlet and outlet chambers during oil flow in and out of the cylinder. However, when using a proportional relief valve for load simulation, its inlet and outlet flows must be equal. This difference in flow characteristics prevents the proportional relief valve's outlet flow from matching the actual return flow of the actuator cylinder during operation.

[0005] In actual operating conditions, when the return oil flow from the cylinder enters the outlet of the multi-way valve, a specific back pressure is generated due to the throttling effect caused by the opening of the multi-way valve 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 cylinder during operation can have additional effects on the system, such as flow regeneration and differential drive. Existing technical solutions cannot accurately match these effects. This flow mismatch severely impacts the accuracy of load simulation, resulting in poor performance evaluation of the construction machinery's powertrain. Summary of the Invention

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

[0008] In the first aspect, in order 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 communicatively connected to the load loading system, and a host computer platform communicatively connected to the vehicle control unit.

[0009] The engineering machinery power system 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 reversing valve connected to the multi-way valve, a proportional overflow valve connected to the three-position four-way reversing valve, a first proportional throttle valve connected between the outlet of the proportional overflow valve and the three-position four-way reversing valve, a second proportional throttle valve and a solenoid valve connected to the outlet of the proportional overflow valve, a third proportional throttle valve connected between the second proportional throttle valve and a second oil tank, and a variable pump connected between the solenoid valve and the second oil tank.

[0011] The three-position four-way reversing valve is configured to enable the inlet of the proportional relief valve to be switched and connected to one of the A oil port and the B oil port of the multi-way valve, and the outlet to be switched and connected to the other of the A oil port and the B oil port.

[0012] In a second aspect, the present application further provides a method for controlling a load simulation loading system based on a construction machinery power system, the method being used to control a load simulation loading system based on a construction machinery power system as described in any of the paragraphs of the first aspect. The closed-loop control method for the load simulation loading system when simulating a cylinder extension condition includes steps A1 to A10.

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

[0014] A2. The driver operates the pilot control handle to output pilot control oil to the signal control valve.

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

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

[0017] A5. The vehicle control unit sends a control current signal, converted from the load spectrum of the construction machinery during field excavation, to the proportional relief valve to control the valve core opening and adjust the proportional relief valve inlet pressure. Oil flows from the proportional relief valve outlet and then 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 the right position to 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 reversing valve. It then uses a proportional-integral-differential algorithm to calculate and correct the error between the first and second pressure values. This allows for real-time adjustment of the control current of the third proportional throttle valve and further adjusts the throttle area of ​​the third proportional throttle valve to ensure that the pressure between the second and third proportional throttle valves is equal to the pressure between the three-position four-way reversing valve and the first proportional throttle valve. During error correction, the proportional component adjusts based on the current error, the integral component eliminates the system's steady-state error, and the differential component predicts the error's changing trend and makes corrections accordingly.

[0020] A8. Based on the simulated area ratio of the rodless cavity to the rod cavity 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 port areas 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.

[0021] A9. Part of the diverted oil flows through the third pressure sensor to the three-position four-way reversing valve, then through the second pressure sensor to port B of the multi-way valve, and then flows back to the first oil tank. The other part flows through the second and third proportional throttle valves and returns to the second oil tank.

[0022] A10. During the control process, the vehicle control unit uses a proportional-integral-differential algorithm to calculate and correct the error between the load spectrum pressure and the first pressure sensor detected by the vehicle control unit. This algorithm adjusts the control current of the proportional relief valve in real time and further adjusts the valve spool opening of the proportional relief valve to ensure that the pressure at port A of the multi-way valve is consistent with the target loading pressure, thus accurately simulating the load and matching the return oil flow rate of the entire construction machinery power system. During error correction, the proportional component adjusts based on the current error, the integral component eliminates the system's steady-state error, and the differential component predicts the error's changing trend and makes corrections accordingly.

[0023] By adopting the above technical solution, the present invention can achieve the following technical effects: The present invention provides a load simulation loading system based on an engineering machinery power system. This solution eliminates the influence of the oil outlet back pressure on the output port pressure of the engineering machinery multi-way valve during the hydraulic load simulation loading process of the engineering machinery using the proportional relief valve, and further balances the oil outlet flow. While simplifying the load simulation loading system, the proportional relief valve is used to completely replace the actuator cylinder, solving the problem of mismatch between the proportional relief valve outlet flow and the actuator cylinder outlet flow, and finally completing the load simulation loading of the engineering machinery power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the specific embodiments of the present invention, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 It is a structural diagram of the load simulation loading system.

[0026] Figure 2 It is a structural diagram of the load simulation loading system when the simulated cylinder is extended.

[0027] Figure 3 It is a structural diagram of the load simulation loading system when the hydraulic cylinder is retracted.

[0028] Markings in the figure: 1-Engineering machinery power system, 2-Load loading system, 3-Vehicle control unit, 4-Upper 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 reversing 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. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0030] Example 1: Figures 1 to 3 As shown, an embodiment of the present 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 communicatively connected to the load loading system 2, and a host computer platform 4 communicatively connected to the vehicle control unit 3.

[0031] 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.

[0032] The load loading system 2 includes a three-position four-way reversing valve 21 connected to the multi-way valve 13, a proportional overflow valve 22 connected to the three-position four-way reversing valve 21, a first proportional throttle valve 27 connected between the outlet of the proportional overflow valve 22 and the three-position four-way reversing valve 21, a second proportional throttle valve 28 and a solenoid valve 211 connected to the outlet of the proportional overflow valve 22, 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.

[0033] The three-position four-way reversing valve 21 is configured to enable the inlet of the proportional relief valve 22 to be switched to communicate with one of the oil ports A and B of the multi-way valve 13 , and the outlet to be switched to communicate with the other of the oil ports A and B.

[0034] Specifically, in this embodiment, the control of both the relief valve and the throttle valve in a construction machinery load simulation system based on a proportional relief valve 22 is electronic. The proportional relief valve 22 has a unidirectional conduction characteristic. In this embodiment, the oil outlet and return ports are switched by controlling the three-position, four-way reversing valve 21 in conjunction with the multi-way valve 13.

[0035] It's understandable that the rod and rodless chambers of a cylinder have different areas, resulting in different flow rates in the two chambers when the hydraulic rod is extended or retracted. For example, if the actuator cylinder's oil inlet chamber is a rodless chamber and its oil outlet chamber is a rod chamber, the actual outlet flow rate of proportional relief valve 22 will be greater than the actual oil outlet flow rate of the actuator cylinder.

[0036] A hydraulic load simulation system typically loads the load by converting a preset load spectrum into a corresponding proportional relief valve 22 control current, driving the valve core opening of the proportional relief valve 22 to achieve the desired pressure at the valve inlet. The oil flow rates at the inlet and outlet of the proportional relief valve 22 are identical. This difference in flow characteristics results in a mismatch between the outlet flow rate of the proportional relief valve 22 and the return oil flow rate of the actual actuator cylinder during operation.

[0037] This embodiment, based on a load simulation loading system for an engineering machinery power system 1, utilizes a proportional relief valve 22 to replace an actuator and cylinder for load simulation loading. It is also equipped with components such as a proportional throttle valve assembly, a solenoid valve 211, a three-position, four-way reversing valve 21, and a motor pump. By controlling the proportional throttle valve and motor pump, the outlet flow of the proportional relief valve 22 is diverted and oil replenished to equalize the oil flow of the actual actuator cylinder. This allows for more accurate simulation of the actuator cylinder, demonstrating outstanding substantive features and significant advancements.

[0038] On the basis of the above embodiment, in an optional embodiment of the present invention, as Figures 1 to 3 As shown, the load loading system 2 also includes a first pressure sensor 23 connected to the oil port A of the multi-way valve 13, a second pressure sensor 24 connected to the oil 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 reversing valve 21, and a fourth pressure sensor 26 connected between the second proportional throttle valve 28 and the third proportional throttle valve 29.

[0039] Specifically, the engineering machinery power system 1 of this embodiment can be replaced with any other power system for engineering machinery that utilizes cylinder-driven actuators. The engineering machinery power system 1 can be expanded based on the number of cylinders in the actual engineering machinery power system 1; this embodiment illustrates only a single cylinder. In this embodiment, the engineering machinery power system 1 provides hydraulic flow to the load loading system 2.

[0040] When the construction machinery power system 1 is in operation, the first drive motor 14 drives the main pump 15 and pilot pump 16 to draw oil from the first oil tank 17 and output the system drive flow and system control flow, respectively. The driver operates the pilot control handle 11 to output the pilot control flow to the signal control valve 12. Based on the flow input from the pilot control handle 11, the signal control valve 12 outputs a corresponding action control flow signal to the multi-way valve 13. The multi-way valve 13 then outputs the drive flow to the load loading system 2.

[0041] At this time, the first and second pressure sensors 23 and 24 in the load-applying 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 ensures that when the output port of the multi-way valve 13 is switched, the output drive flow always flows 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, second, and third proportional throttle valves 27, 28, and 29 are used to adjust the flow rate between the outlet of the proportional relief valve 22 and the oil return port of the multi-way valve 13. The solenoid valve 211 is used to shut off the oil flow from the proportional relief valve 22 to the variable pump 212. The second oil tank 213 provides the oil source for the variable pump 212. The second driving motor 210 is used to drive the variable displacement pump 212 to output flow.

[0042] Preferably, the multi-way valve 13 is provided with a control port, an oil inlet, an oil outlet, an oil port A, and an oil port B. The control port is configured to control the oil inlet to switch between communicating with one of the oil ports A and B, while simultaneously controlling the oil outlet to switch between communicating with the other of the two ports (i.e., the port not connected to the oil inlet). The control port is coupled to the signal control valve 12. The oil inlet is coupled to the main pump 15. The oil outlet is coupled to the oil tank.

[0043] The connection scheme of the hydraulic pipeline of a load simulation loading system based on an engineering machinery power system 1 according to an embodiment of the present invention is specifically as follows: the main pump 15 and the pilot pump 16 are connected to the first oil tank 17 through a hydraulic pipe to absorb oil. The main pump 15 is connected to the multi-way valve 13 pipeline for supplying oil to the multi-way valve 13. The pilot pump 16 is connected to the pilot control handle 11 pipeline to supply oil to the pilot control handle 11. The pilot control handle 11 is connected to the signal control valve 12 pipeline. The signal control valve 12 is connected to the multi-way valve 13 pipeline. The signal control valve 12 provides a secondary pilot pressure for controlling the opening of each valve port inside the multi-way valve 13, and controlling the oil inlet to switch to connect to one of the oil port A and the oil port B.

[0044] The first pressure sensor 23 is connected via a tee to pipe 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 pipe 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 pipeline 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 pipeline between the second proportional throttle valve 28 and the third proportional throttle valve 29.

[0045] The two interfaces on one side of the three-position four-way reversing valve 21 are respectively connected to the A oil port and B oil port pipelines of the multi-way valve 13, and the two interfaces on the other side are respectively connected to the inlet of the proportional relief valve 22 and the first proportional throttle valve 27 pipeline.

[0046] The outlet of proportional relief valve 22 is connected to the first proportional throttle valve 27, the second proportional throttle valve 28, and the solenoid valve 211 via a four-way pipe 214. The second proportional throttle valve 28 is connected to the third proportional throttle valve 29 via a pipe, and the solenoid valve 211 is connected to the outlet pipe of the variable pump 212. The low-pressure outlet of the third proportional throttle valve 29 is connected to the oil suction port of the variable pump 212 via a pipe, and then to the second fuel tank 213. It should be noted that the first fuel tank 17 and the second fuel tank 213 can be the same tank or two separate tanks; both solutions fall within the scope of protection of the present invention.

[0047] An electrical circuit connection scheme of a load simulation loading system based on an engineering machinery power system 1 in an embodiment of the present invention is: 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 quantity receiving port of the vehicle control unit 3.

[0048] 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 to control the throttle 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 generating port on the vehicle control unit 3.

[0049] The vehicle control unit 3 is electrically connected to the three-position four-way directional valve 21 and the electromagnet of the solenoid valve 211. The vehicle control unit 3 sends electrical signals to control the three-position four-way directional valve 21 and the electromagnet of the solenoid valve 211 to be energized, thereby reversing the valve core.

[0050] Preferably, Figures 1 to 3As shown, the engineering machinery power system 1 also includes a first drive motor 14 coupled to the main pump 15. The load applying system 2 includes a second drive motor 210 coupled to the variable displacement 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 via a gear transmission. The second drive motor 210 is mechanically connected to the variable displacement pump 212 via a splined bushing.

[0051] 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 displacement mechanism control port of the variable displacement pump 212. The vehicle control unit 3 drives the motor pump by sending control electrical signals to the enable signal receiving port of the second drive motor 210 and the variable displacement mechanism control port of the variable displacement pump 212. Because the power supply method of the drive motor does not affect the system and algorithm functions described in this embodiment, this embodiment omits the power supply connection between the first drive motor 14 and the second drive motor 210.

[0052] Preferably, the vehicle control unit 3 and the host computer platform 4 use Peak-CAN to communicate via the CAN bus. The host computer platform 4 imports the written program into the vehicle control unit 3 and detects the changes in various parameters collected by the controller in real time.

[0053] The vehicle control unit 3 and the host computer platform 4 exchange data using CAN communication. The host computer platform 4 writes control programs and pre-configured load profiles and imports them 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, second, third, and fourth pressure sensors 23, 24, 25, and 26, and converts them into actual pressure signals using a formula. The vehicle control unit 3 sends electrical signals to energize the electromagnets of the three-position, four-way directional valve 21, causing it to switch direction. The vehicle control unit 3 also sends electrical signals of varying magnitude to energize the electromagnets of the first, second, and third proportional throttle valves 27, 28, and 29, adjusting the throttle area of ​​each valve. The vehicle control unit 3 controls the switching of the valve core position of the solenoid valve 211 by sending an electrical signal to the solenoid valve 211 , and further controls the on-off of the oil circuit between the proportional relief valve 22 and the variable displacement pump 212 .

[0054] The following describes, using an actuator cylinder of a construction machine as an example, how to simulate load loading on the construction machine power system 1 by replacing the actuator cylinder with the load simulation loading system proposed in this embodiment. The actuator cylinder primarily operates in, but is not limited to, extension and retraction conditions.

[0055] When simulating the extension of an actuator cylinder, the load simulation system in this embodiment: Port A of multi-way valve 13 delivers oil, while port B returns oil. Proportional relief valve 22 is loaded with pressure to simulate the driving pressure of the rodless chamber of an engineering machinery cylinder. At this point, the outlet flow of proportional relief valve 22 is greater than the actual cylinder oil flow, necessitating flow diversion.

[0056] like Figure 2 As shown, the closed-loop control method of the load simulation loading system when simulating the cylinder extension working condition includes steps A1 to A10.

[0057] A1, the first drive motor 14 drives the main pump 15 and the pilot pump 16 to suck oil from the first oil tank 17, and output the oil to the multi-way valve 13 and the pilot control handle 11 respectively.

[0058] A2. The driver operates the pilot control handle 11 to output the pilot control oil to the signal control valve 12.

[0059] 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 oil port of the multi-way valve 13.

[0060] A4. The oil output from the multi-way valve 13 reaches the three-position four-way directional valve 21 through the first pressure sensor 23. 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.

[0061] A5. Vehicle control unit 3 sends a control current signal, converted from the load spectrum of the construction machinery during on-site excavation, to proportional relief valve 22 to control the valve core opening and adjust the inlet pressure of proportional relief valve 22. Oil flows out of the outlet of proportional relief valve 22 and then passes through four-way valve 214 to reach first proportional throttle valve 27, second proportional throttle valve 28, and solenoid valve 211.

[0062] A6. The vehicle control unit 3 sends a control electrical signal to drive the solenoid valve 211 to the right position to 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.

[0063] A7. The vehicle control unit 3 collects the first pressure value from the fourth pressure sensor 26 between the second and third proportional throttle valves 28 and 29, and the second pressure value from the third pressure sensor 25 between the first and third proportional throttle valves 27 and the three-position four-way reversing valve 21. It then uses a proportional-integral-differential algorithm to calculate the error between the first and second pressure values ​​and corrects them. This allows for real-time adjustment of the control current of the third proportional throttle valve 29 and further adjusts the throttle area of ​​the third proportional throttle valve 29 to ensure that the pressure between the second and third proportional throttle valves 28 and 29 is the same as the pressure between the three-position four-way reversing valve 21 and the first proportional throttle valve 27. During error correction, the proportional component adjusts based on the current error, the integral component eliminates the system's steady-state error, and the differential component predicts the error's changing trend and makes corrections.

[0064] Specifically, by controlling the fourth pressure and the third pressure to maintain a balance, a pressure basis can be provided for the next step of controlling the diversion of the first proportional throttle valve 27 and the second proportional throttle valve 28, so that the diversion flow can be accurately controlled, which has outstanding substantial characteristics and significant progress.

[0065] A8. Based on the simulated area ratio of the rodless cavity to the rod cavity of the 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 port areas of the first proportional throttle valve 27 and the second proportional throttle valve 28, thereby controlling the oil flow through the first proportional throttle valve 27 and the second proportional throttle valve 28.

[0066] The valve port throttling formula is: .

[0067] Where, The oil flow rate, is the flow coefficient, is the throttle area, is the pressure difference before and after the throttle valve, is the density of hydraulic oil.

[0068] According to the valve orifice throttling formula, when the flow coefficient and the pressure difference before and after the throttle valve remain unchanged, the flow through the throttle valve is only related to the throttle orifice area. Step A8 specifically includes steps A81 to A82.

[0069] A81. Obtain the cross-sectional area of ​​the rodless cavity , cross-sectional area of ​​the rod cavity .

[0070] 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 throttle port area ratio of the first proportional throttle valve and the second proportional throttle valve to , thereby controlling the oil flow ratio through the first proportional throttle valve and the second proportional throttle valve.

[0071] Specifically, at this point, the pressure differentials across the first and second proportional throttle valves 27, 28 are the same, and the flow rates through the first and second proportional throttle valves 27, 28 are affected only by the throttle opening areas of the first and second proportional throttle valves 27, 28. The vehicle control unit 3 controls the flow rates through the first and second proportional throttle valves 27, 28 by adjusting the throttle opening area ratio of the first and second proportional throttle valves 27, 28.

[0072] Assuming that the area ratio of the rodless cavity and the rod cavity of the simulated actual cylinder is 4:3, 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 port area of ​​the first proportional throttle valve 27 and the second proportional throttle valve 28 to 3:1, so that the flow through the first proportional throttle valve 27 is 3 / 4 of the inlet flow of the proportional relief valve 22, which meets the flow relationship of the actual cylinder oil inlet and oil return.

[0073] The control method of this embodiment controls the pressure difference before and after the proportional throttle valve of the proportional throttle valve group to remain unchanged and the throttle port area, and then adjusts the throttle port area ratio of each proportional throttle valve to achieve the diversion of the outlet flow of the proportional relief valve 22, so that the outlet flow of the proportional relief valve 22 reaching the multi-way valve 13 is equal to the flow of the actual actuator cylinder returning to the multi-way valve 13, which can more realistically simulate the pressure conditions of the actual actuator cylinder, and has outstanding substantial characteristics and significant progress.

[0074] A9. Part of the diverted oil flows through the third pressure sensor 25 to the three-position four-way reversing valve 21, then through the second pressure sensor 24 to the oil port B of the multi-way valve 13, and then flows back to the first oil tank 17. The other part flows through the second proportional throttle valve 28 and the third proportional throttle valve 29 to return to the second oil tank 213.

[0075] A10. During the control process, the vehicle control unit 3 uses a proportional-integral-differential algorithm to calculate and correct the error between the load spectrum pressure and the data collected by the first pressure sensor 23. This algorithm adjusts the control current of the proportional relief valve 22 in real time and further adjusts the valve core opening of the proportional relief valve 22 to ensure that the pressure at port A of the multi-way valve 13 is consistent with the target loading pressure, thereby accurately simulating the load of the entire construction machinery power system and matching the return oil flow rate. During error correction, the proportional component adjusts based on the current error, the integral component eliminates the system's steady-state error, and the differential component predicts the error's changing trend and makes corrections accordingly.

[0076] Specifically, when simulating the extension condition of the actuator cylinder, where the oil inlet chamber is a rod-type chamber and the oil outlet chamber is a rodless chamber, the actual outlet flow rate of the proportional relief valve 22 is less than the actual oil outlet flow rate of the actuator cylinder. The load simulation loading system of this embodiment controls the coordinated operation of the throttle valve assembly, solenoid valve 211, and motor pump to replenish the oil outlet flow rate of the proportional relief valve 22. 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 oil outlet of the actuator cylinder to the multi-way valve 13, achieving precise load simulation of the engineering machinery power system 1 and representing a significant improvement.

[0077] This control method achieves precise flow diversion at the outlet of proportional relief valve 22. Furthermore, this embodiment addresses the impact of additional pressure from a complex hydraulic system on the pressure at the output port of multi-way valve 13 by implementing a proportional-integral-differential algorithm in the vehicle control unit 3 to implement closed-loop control of the pressure at the output port of multi-way valve 13.

[0078] When simulating the retraction of an actuator cylinder, the load simulation system in this embodiment: oil flows out of port B of multi-way valve 13 and returns to port A. Proportional relief valve 22 is loaded with pressure to simulate the rod chamber drive pressure of the construction machinery cylinder. At this point, the outlet flow of proportional relief valve 22 is less than the actual cylinder oil flow, necessitating oil replenishment.

[0079] like Figure 3 As shown, the closed-loop control method of the load simulation loading system when simulating the cylinder retraction working condition includes steps B1 to B10.

[0080] B1. The first drive motor 14 drives the main pump 15 and the pilot pump 16 to suck oil from the first oil tank 17 and output the oil to the multi-way valve 13 and the pilot control handle 11 respectively.

[0081] B2. The driver operates the pilot control handle 11 to output the pilot control oil to the signal control valve 12.

[0082] B3, the signal control valve 12 outputs the 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 oil port of the multi-way valve 13.

[0083] 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.

[0084] B5. Vehicle control unit 3 sends a control current signal, converted from the load spectrum of the construction machinery during on-site excavation, to proportional relief valve 22 to control the valve core opening and adjust the inlet pressure of proportional relief valve 22. Oil flows out of the outlet of proportional relief valve 22, then passes through four-way valve 214 to reach first proportional throttle valve 27, second proportional throttle valve 28, and solenoid valve 211.

[0085] B6. The vehicle control unit 3 sends a control electrical signal to drive the solenoid valve 211 to 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.

[0086] B7. The vehicle control unit 3 sends control electrical signals to the first proportional throttle valve 27 and the second proportional throttle valve 28, so that the valve port of the first proportional throttle valve 27 is fully opened and the valve port of the second proportional throttle valve 28 is completely closed.

[0087] 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 cavity and the rod cavity of the simulated actuator cylinder (i.e., calculates the flow difference between the rod cavity and the rodless cavity of the actual cylinder), so as to drive the variable mechanism to output hydraulic oil to replenish the outlet flow of the proportional relief valve 22 for merging.

[0088] B9. The oil after merging passes through the first proportional throttle valve 27 and the three-position four-way reversing valve 21 to reach the oil port A of the multi-way valve 13 and flows back to the first oil tank 17.

[0089] B10. During the control process, the vehicle control unit 3 uses a proportional-integral-differential algorithm to calculate and correct the error between the load spectrum pressure and the data collected by the second pressure sensor 24. This algorithm adjusts the control current of the proportional relief valve 22 in real time and further adjusts the valve core opening of the proportional relief valve 22 to ensure that the pressure at port B of the multi-way valve 13 is consistent with the target loading pressure. This accurately simulates the load of the construction machinery's power system and matches the return oil flow rate. During error correction, the proportional component adjusts based on the current error, the integral component eliminates the system's steady-state error, and the differential component predicts the error's changing trend and makes corrections accordingly.

[0090] In this embodiment, the pressure at the output port of the multi-way valve 13 is affected by the additional pressure caused by the complex hydraulic system. A proportional-integral-differential algorithm is additionally used in the vehicle control unit 3 to perform closed-loop control on the pressure at the output port of the multi-way valve 13.

[0091] The control method of this embodiment is adaptable to the actuator cylinder parameters of various types of engineering machinery. By collaboratively controlling 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, closed-loop control of the pressure at the output port of the multi-way valve 13 is achieved through a proportional-integral-differential algorithm, avoiding error fluctuations in the pressure at the output port of the multi-way valve 13 caused by the complex hydraulic system, thus achieving precise control.

[0092] The present 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 differential before and after the throttle valve to remain constant and the throttle valve port area to achieve diversion of the outlet flow of the proportional relief valve 22, and by controlling the coordinated operation of the motor pump, the throttle valve, and the solenoid valve 211 to replenish the outlet flow of the proportional relief valve 22, accurate load simulation loading of the engineering machinery power system 1 is completed, simplifying the volume of the load simulation loading system. At the same time, 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 engineering machinery's oil cylinder, and further improves the load simulation loading of the oil outlet pressure of the engineering machinery's multi-way valve 13.

[0093] The load simulation system incorporates a proportional throttle valve, a proportional relief valve 22, a solenoid valve 211, and a motor pump assembly. This solves the mismatch between the return oil flow and the actual cylinder return oil flow during pressure load simulation using the proportional relief valve 22 in conventional construction machinery. The closed-loop control method utilizes a proportional-integral-differential algorithm to control the proportional throttle valve and proportional relief valve 22, significantly improving the system's response speed and accuracy.

[0094] Embodiment 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 Embodiment 1.

[0095] The closed-loop control method of the load simulation loading system when simulating the oil cylinder extension working condition includes steps A1 to A10.

[0096] A1. The first drive motor drives the main pump and the pilot pump to suck oil from the first oil tank and output the oil to the multi-way valve and the pilot control handle respectively.

[0097] A2. The driver operates the pilot control handle to output pilot control oil to the signal control valve.

[0098] A3. The signal control valve outputs the corresponding action control flow signal to the multi-way valve according to the input flow of the pilot control handle to drive the oil to be output from the A oil port of the multi-way valve.

[0099] A4. The oil output from the multi-way valve passes through the first pressure sensor and reaches the three-position four-way directional valve. At this time, the vehicle control unit sends a control electrical signal to drive the three-position four-way directional valve to the left position, so that the oil passes through the three-position four-way directional valve and reaches the inlet of the proportional relief valve.

[0100] A5. The vehicle control unit sends a control current signal, converted from the load spectrum of the construction machinery during field excavation, to the proportional relief valve to control the valve core opening and adjust the proportional relief valve inlet pressure. Oil flows from the proportional relief valve outlet and then through the four-way valve to the first proportional throttle valve, the second proportional throttle valve, and the solenoid valve.

[0101] A6. The vehicle control unit sends a control electrical signal to drive the solenoid valve to the right position to 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.

[0102] 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 reversing valve. It then uses a proportional-integral-differential algorithm to calculate and correct the error between the first and second pressure values. This allows for real-time adjustment of the control current of the third proportional throttle valve and further adjusts the throttle area of ​​the third proportional throttle valve to ensure that the pressure between the second and third proportional throttle valves is equal to the pressure between the three-position four-way reversing valve and the first proportional throttle valve. During error correction, the proportional component adjusts based on the current error, the integral component eliminates the system's steady-state error, and the differential component predicts the error's changing trend and makes corrections accordingly.

[0103] A8. Based on the simulated area ratio of the rodless cavity to the rod cavity 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 port areas 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.

[0104] A9. Part of the diverted oil flows through the third pressure sensor to the three-position four-way reversing valve, then through the second pressure sensor to port B of the multi-way valve, and then flows back to the first oil tank. The other part flows through the second and third proportional throttle valves and returns to the second oil tank.

[0105] A10. During the control process, the vehicle control unit uses a proportional-integral-differential 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 algorithm adjusts the control current of the proportional relief valve in real time and further adjusts the valve core opening of the proportional relief valve to ensure that the pressure at port A of the multi-way valve is consistent with the target loading pressure. This accurately simulates the load of the entire construction machinery power system and matches the return oil flow rate. During error correction, the proportional component adjusts based on the current error, the integral component eliminates the system's steady-state error, and the differential component predicts the error's changing trend and makes corrections accordingly.

[0106] On the basis of the above embodiment, in an optional embodiment of the present invention, when simulating the cylinder retraction working condition, the closed-loop control method of the load simulation loading system includes steps B1 to B10.

[0107] B1. The first drive motor drives the main pump and the pilot pump to suck oil from the first oil tank and output the oil to the multi-way valve and the pilot control handle respectively.

[0108] B2. The driver operates the pilot control handle to output pilot control oil to the signal control valve.

[0109] B3, the signal control valve outputs the corresponding action control flow signal to the multi-way valve according to the input flow of the pilot control handle, so as to drive the oil to be output from the B oil port of the multi-way valve.

[0110] B4. The oil output from the multi-way valve passes through the second pressure sensor and reaches the three-position four-way directional valve. At this time, the vehicle control unit sends a control electrical signal to drive the three-position four-way directional valve to the right position. Then the oil passes through the three-position four-way directional valve and reaches the inlet of the proportional relief valve.

[0111] B5. The vehicle control unit sends a control current signal, converted from the load spectrum of the construction machinery during field excavation, to the proportional relief valve to control the valve core opening and adjust the proportional relief valve inlet pressure. Oil flows from the proportional relief valve outlet and then through the four-way valve to the first proportional throttle valve, the second proportional throttle valve, and the solenoid valve.

[0112] B6. The vehicle control unit sends a control electrical signal to drive the solenoid valve to 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.

[0113] 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.

[0114] B8. The vehicle control unit sends a control signal to the second drive motor and the variable mechanism of the variable pump based on the simulated area ratio of the rodless cavity and the rod cavity of the actuator cylinder. This drives the variable mechanism to output hydraulic oil to replenish the flow at the proportional relief valve outlet.

[0115] B9. After merging, the oil passes through the first proportional throttle valve and the three-position four-way reversing valve to reach the A oil port of the multi-way valve and flows back to the first oil tank.

[0116] B10. During the control process, the vehicle control unit uses a proportional-integral-differential algorithm to calculate and correct the error between the load spectrum pressure and the second pressure sensor collected by the vehicle control unit. This algorithm adjusts the control current of the proportional relief valve in real time and further adjusts the valve spool opening of the proportional relief valve to ensure that the pressure at port B of the multi-way valve is consistent with the target loading pressure. This accurately simulates the load of the entire construction machinery power system and matches the return oil flow rate. During error correction, the proportional component adjusts based on the current error, the integral component eliminates the system's steady-state error, and the differential component predicts the error's changing trend and makes corrections accordingly.

[0117] Obviously, the above detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but is merely a preferred embodiment of the present invention, not all embodiments, and is not intended to limit the present invention. For those skilled in the art, the present invention may have various changes and variations. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work, any modifications, equivalent substitutions, improvements, etc., are within the scope of protection of the present invention.

Claims

1. A load simulation loading system based on an engineering machinery power system (1), characterized in that: It comprises an engineering machinery power system (1), a load loading system (2), a vehicle control unit (3) communicatively connected to the load loading system (2), and a host computer platform (4) communicatively connected to the vehicle control unit (3); The engineering machinery power system (1) comprises 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); The load loading system (2) includes a three-position four-way reversing valve (21) connected to the multi-way valve (13), a proportional relief valve (22) connected to the three-position four-way reversing valve (21), a first proportional throttle valve (27) connected between the outlet of the proportional relief valve (22) and the three-position four-way reversing valve (21), a second proportional throttle valve (28) and a solenoid valve (211) connected to the outlet of the proportional relief valve (22), a third proportional throttle valve (29) connected between the second proportional throttle valve (28) and a second oil tank (213), and a variable pump (212) connected between the solenoid valve (211) and the second oil tank (213); The three-position four-way reversing valve (21) is constructed so that the inlet of the proportional relief valve (22) can be switched to be connected to one of the oil ports A and B of the multi-way valve (13), and the outlet can be switched to be connected to the other of the oil ports A and B.

2. A load simulation loading system based on an engineering machinery power system (1) according to claim 1, characterized in that: The multi-way valve (13) is provided with a control port, an oil inlet, an oil outlet, an A oil port, and a B oil port; the control port is configured to control the oil inlet to switch and connect to one of the A oil port and the B oil port, and simultaneously control the oil outlet to switch and connect to the other of the A oil port and the B oil port; the control port is connected to the signal control valve (12); the oil inlet is connected to the main pump (15); and the oil outlet is connected to the oil tank.

3. A load simulation loading system based on an engineering machinery power system (1) according to claim 1, characterized in that: The load loading system (2) further includes a first pressure sensor (23) coupled to the oil port A of the multi-way valve (13), a second pressure sensor (24) coupled to the oil port B of the multi-way valve (13), a third pressure sensor (25) coupled between the first proportional throttle valve (27) and the three-position four-way reversing valve (21), and a fourth pressure sensor (26) coupled between the second proportional throttle valve (28) and the third proportional throttle valve (29).

4. A load simulation loading system based on an engineering machinery power system (1) according to claim 3, characterized in that: 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 receiving port of the vehicle control unit (3); 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 send a control current signal through a PWM generating port on the vehicle control unit (3) to control the throttle port 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); The vehicle control unit (3) is electrically connected to the three-position four-way directional valve (21) and the electromagnet of the solenoid valve (211); the vehicle control unit (3) controls the three-position four-way directional valve (21) and the electromagnet of the solenoid valve (211) to be energized by sending electrical signals, thereby causing the valve core to be reversed.

5. A load simulation loading system based on an engineering machinery power system (1) according to claim 3, characterized in that: The engineering machinery power system (1) further comprises a first drive motor (14) coupled to the main pump (15); the load loading system (2) comprises a second drive motor (210) coupled to the variable displacement pump (212); 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 a control electrical signal to the enable signal receiving port of the second drive motor (210) and the variable mechanism control port of the variable pump (212).

6. A load simulation loading system based on an engineering machinery power system (1) according to any one of claims 3 to 5, characterized in that: When simulating the extension working condition of the actuator cylinder: the oil port A of the multi-way valve (13) is discharged, the oil port B is returned, and the proportional relief valve (22) is loaded with pressure to simulate the driving pressure of the rodless chamber of the engineering machinery oil cylinder; At this time, the outlet flow of the proportional relief valve (22) is greater than the actual oil flow of the cylinder, and the outlet flow of the proportional relief valve (22) needs to be diverted; The closed-loop control method of the load simulation loading system when simulating the cylinder extension working condition is: The first drive motor (14) drives the main pump (15) and the pilot pump (16) to suck oil from the first oil tank (17) and output the oil to the multi-way valve (13) and the pilot control handle (11) respectively; The driver operates the pilot control handle (11) to output the pilot control oil to the signal control valve (12); 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 oil port A of the multi-way valve (13); The oil outputted by the multi-way valve (13) passes through the first pressure sensor (23) and reaches the three-position four-way reversing valve (21). At this time, the vehicle control unit (3) sends a control electrical signal to drive the three-position four-way reversing valve (21) to work in the left position, so that the oil passes through the three-position four-way reversing valve (21) and reaches the inlet of the proportional relief valve (22). The vehicle control unit (3) sends a control current signal converted from the load spectrum of the construction machinery during on-site excavation to the proportional relief valve (22) to control the 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 reach the first proportional throttle valve (27), the second proportional throttle valve (28), and the solenoid valve (211); The vehicle control unit (3) sends a control electrical signal to drive the solenoid valve (211) to the right position to 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); The vehicle control unit (3) collects the first pressure value of the fourth pressure sensor (26) between the second proportional throttle valve (28) and the third proportional throttle valve (29) and the second pressure value of the third pressure sensor (25) between the first proportional throttle valve (27) and the three-position four-way reversing valve (21), and then uses the proportional-integral-differential algorithm to calculate the error between the first pressure value and the second pressure value and correct it, so as to adjust the control current of the third proportional throttle valve (29) in real time, and further adjust the throttle port area of ​​the third proportional throttle valve (29) so 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 reversing valve (21) and the first proportional throttle valve (27); wherein, when correcting the error, the proportional part is adjusted according to the current error, the integral part eliminates the steady-state error of the system, and the differential part predicts the change trend of the error and corrects it; According to the area ratio of the rodless cavity and the rod cavity 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 port area of ​​the first proportional throttle valve (27) and the second proportional throttle valve (28), thereby controlling the oil flow through the first proportional throttle valve (27) and the second proportional throttle valve (28); A portion of the oil after diversion passes through the third pressure sensor (25) to reach the three-position four-way reversing valve (21), and then passes through the second pressure sensor (24) to reach the oil port B of the multi-way valve (13) to flow back to the first oil tank (17); the other portion passes through the second proportional throttle valve (28) and the third proportional throttle valve (29) to return to the second oil tank (213); During the control process, the vehicle control unit (3) calculates the error between the load spectrum pressure and the first pressure sensor (23) collected by the vehicle control unit (3) using a proportional-integral-differential algorithm and makes corrections, so as to adjust the control current of the proportional relief valve (22) in real time, and further adjust the valve core opening of the proportional relief valve (22) so that the pressure of the oil port A of the multi-way valve (13) is consistent with the target loading pressure, thereby completing the matching of the load of the engineering machinery power system with the return oil flow rate through accurate simulation; wherein, when correcting the error, the proportional part is adjusted according to the current error, the integral part eliminates the steady-state error of the system, and the differential part predicts the change trend of the error and makes corrections.

7. The load simulation loading system based on the engineering machinery power system according to claim 6, characterized in that: The vehicle control unit sends a control electrical signal to the first proportional throttle valve and the second proportional throttle valve based on the area ratio of the rodless cavity and the rod cavity of the simulated actuator cylinder to adjust the throttle port areas 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, specifically including: The valve port throttling formula is: ； Where, The oil flow rate, is the flow coefficient, is the throttle area, is the pressure difference before and after the throttle valve, is the density of hydraulic oil; According to the valve port throttling formula, when the flow coefficient and the pressure difference before and after the throttle valve remain unchanged, the flow rate through the throttle valve is only related to the throttle port area; Get the cross-sectional area of ​​the rodless cavity , cross-sectional area of ​​the rod cavity ; 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 port area ratio of the first proportional throttle valve and the second proportional throttle valve to , thereby controlling the oil flow ratio through the first proportional throttle valve and the second proportional throttle valve.

8. A load simulation loading system based on an engineering machinery power system (1) according to any one of claims 3 to 5, characterized in that: When simulating the retraction working condition of the actuator cylinder: the B oil port of the multi-way valve (13) is discharged, the A oil port is returned, and the proportional relief valve (22) is loaded with pressure to simulate the driving pressure of the rod chamber of the engineering machinery cylinder; At this time, the outlet flow of the proportional relief valve (22) is less than the actual oil flow of the cylinder, and the outlet flow of the proportional relief valve (22) needs to be supplemented with oil; When simulating the cylinder retraction condition, the closed-loop control method of the load simulation loading system is: The first drive motor (14) drives the main pump (15) and the pilot pump (16) to suck oil from the first oil tank (17) and output the oil to the multi-way valve (13) and the pilot control handle (11) respectively; The driver operates the pilot control handle (11) to output the pilot control oil to the signal control valve (12); 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 oil port of the multi-way valve (13); The oil outputted by the multi-way valve (13) passes through the second pressure sensor (24) and reaches the three-position four-way reversing valve (21). At this time, the vehicle control unit (3) sends a control electrical signal to drive the three-position four-way reversing valve (21) to work in the right position. Then, the oil passes through the three-position four-way reversing valve (21) and reaches the inlet of the proportional relief valve (22). The vehicle control unit (3) sends a control current signal converted from the load spectrum of the construction machinery during on-site excavation to the proportional relief valve (22) to control the 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 reach the first proportional throttle valve (27), the second proportional throttle valve (28), and the solenoid valve (211); 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); The vehicle control unit (3) sends a control electrical signal to the first proportional throttle valve (27) and the second proportional throttle valve (28), so that the valve port of the first proportional throttle valve (27) is fully opened and the valve port of the second proportional throttle valve (28) is completely closed; 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) according to the area ratio of the rodless cavity and the rod cavity of the simulated actuator cylinder, so as to drive the variable mechanism to output hydraulic oil to supplement the outlet flow of the proportional relief valve (22) for merging; The combined oil flows through the first proportional throttle valve (27) and the three-position four-way reversing valve (21) to reach the oil port A of the multi-way valve (13) to flow back to the first oil tank (17); During the control process, the vehicle control unit (3) calculates the error between the load spectrum pressure and the second pressure sensor (24) collected by the vehicle control unit (3) using a proportional-integral-differential algorithm and makes corrections, so as to adjust the control current of the proportional relief valve (22) in real time, and further adjust the valve core opening of the proportional relief valve (22) so that the pressure of the B oil port of the multi-way valve (13) is consistent with the target loading pressure, so as to complete the matching of the load accurate simulation loading and return oil flow of the power system of the engineering machinery; wherein, when correcting the error, the proportional part is adjusted according to the current error, the integral part eliminates the steady-state error of the system, and the differential part predicts the change trend of the error and makes corrections.

9. A control method for a load simulation loading system based on an engineering machinery power system (1), characterized in that: Used to control a load simulation loading system based on an engineering machinery power system (1) as described in any one of claims 1 to 8; The closed-loop control method of the load simulation loading system when simulating the cylinder extension working condition is: The first drive motor (14) drives the main pump (15) and the pilot pump (16) to suck oil from the first oil tank (17) and output the oil to the multi-way valve (13) and the pilot control handle (11) respectively; The driver operates the pilot control handle (11) to output the pilot control oil to the signal control valve (12); 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 oil port A of the multi-way valve (13); The oil outputted by the multi-way valve (13) passes through the first pressure sensor (23) and reaches the three-position four-way reversing valve (21). At this time, the vehicle control unit (3) sends a control electrical signal to drive the three-position four-way reversing valve (21) to work in the left position, so that the oil passes through the three-position four-way reversing valve (21) and reaches the inlet of the proportional relief valve (22). The vehicle control unit (3) sends a control current signal converted from the load spectrum of the construction machinery during on-site excavation to the proportional relief valve (22) to control the 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 reach the first proportional throttle valve (27), the second proportional throttle valve (28), and the solenoid valve (211); The vehicle control unit (3) sends a control electrical signal to drive the solenoid valve (211) to the right position to 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); The vehicle control unit (3) collects the first pressure value of the fourth pressure sensor (26) between the second proportional throttle valve (28) and the third proportional throttle valve (29) and the second pressure value of the third pressure sensor (25) between the first proportional throttle valve (27) and the three-position four-way reversing valve (21), and then uses the proportional-integral-differential algorithm to calculate the error between the first pressure value and the second pressure value and correct it, so as to adjust the control current of the third proportional throttle valve (29) in real time, and further adjust the throttle port area of ​​the third proportional throttle valve (29) so 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 reversing valve (21) and the first proportional throttle valve (27); wherein, when correcting the error, the proportional part is adjusted according to the current error, the integral part eliminates the steady-state error of the system, and the differential part predicts the change trend of the error and corrects it; According to the area ratio of the rodless cavity and the rod cavity 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 port area of ​​the first proportional throttle valve (27) and the second proportional throttle valve (28), thereby controlling the oil flow through the first proportional throttle valve (27) and the second proportional throttle valve (28); A portion of the oil after diversion passes through the third pressure sensor (25) to reach the three-position four-way reversing valve (21), and then passes through the second pressure sensor (24) to reach the oil port B of the multi-way valve (13) to flow back to the first oil tank (17); the other portion passes through the second proportional throttle valve (28) and the third proportional throttle valve (29) to return to the second oil tank (213); During the control process, the vehicle control unit (3) calculates the error between the load spectrum pressure and the first pressure sensor (23) collected by the vehicle control unit (3) using a proportional-integral-differential algorithm and makes corrections, so as to adjust the control current of the proportional relief valve (22) in real time, and further adjust the valve core opening of the proportional relief valve (22) so that the pressure of the oil port A of the multi-way valve (13) is consistent with the target loading pressure, thereby completing the matching of the load of the engineering machinery power system with the return oil flow rate through accurate simulation; wherein, when correcting the error, the proportional part is adjusted according to the current error, the integral part eliminates the steady-state error of the system, and the differential part predicts the change trend of the error and makes corrections.

10. A control method for a load simulation loading system based on an engineering machinery power system (1) according to claim 9, characterized in that: When simulating the cylinder retraction condition, the closed-loop control method of the load simulation loading system is: The first drive motor (14) drives the main pump (15) and the pilot pump (16) to suck oil from the first oil tank (17) and output the oil to the multi-way valve (13) and the pilot control handle (11) respectively; The driver operates the pilot control handle (11) to output the pilot control oil to the signal control valve (12); 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 oil port of the multi-way valve (13); The oil outputted by the multi-way valve (13) passes through the second pressure sensor (24) and reaches the three-position four-way reversing valve (21). At this time, the vehicle control unit (3) sends a control electrical signal to drive the three-position four-way reversing valve (21) to work in the right position. Then, the oil passes through the three-position four-way reversing valve (21) and reaches the inlet of the proportional relief valve (22). The vehicle control unit (3) sends a control current signal converted from the load spectrum of the construction machinery during on-site excavation to the proportional relief valve (22) to control the 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 reach the first proportional throttle valve (27), the second proportional throttle valve (28), and the solenoid valve (211); 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); The vehicle control unit (3) sends a control electrical signal to the first proportional throttle valve (27) and the second proportional throttle valve (28), so that the valve port of the first proportional throttle valve (27) is fully opened and the valve port of the second proportional throttle valve (28) is completely closed; 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) according to the area ratio of the rodless cavity and the rod cavity of the simulated actuator cylinder, so as to drive the variable mechanism to output hydraulic oil to supplement the outlet flow of the proportional relief valve (22) for merging; The combined oil flows through the first proportional throttle valve (27) and the three-position four-way reversing valve (21) to reach the oil port A of the multi-way valve (13) to flow back to the first oil tank (17); During the control process, the vehicle control unit (3) calculates the error between the load spectrum pressure and the second pressure sensor (24) collected by the vehicle control unit (3) using a proportional-integral-differential algorithm and makes corrections, so as to adjust the control current of the proportional relief valve (22) in real time, and further adjust the valve core opening of the proportional relief valve (22) so that the pressure of the B oil port of the multi-way valve (13) is consistent with the target loading pressure, so as to complete the matching of the load accurate simulation loading and return oil flow of the power system of the engineering machinery; wherein, when correcting the error, the proportional part is adjusted according to the current error, the integral part eliminates the steady-state error of the system, and the differential part predicts the change trend of the error and makes corrections.

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