A real-time load simulation system for a hydraulic excavator power system

Abstract

A real-time load simulation system for a hydraulic excavator power system is disclosed, relating to the field of hydraulic excavator technology. The system comprises an excavator power system, a load-loading hydraulic system, a vehicle control unit, and a co-simulation system. The excavator power system includes an oil tank, a main pump, a pilot pump, a pilot hydraulic control handle, a signal control valve, and a multi-way valve. The load-loading hydraulic system includes a check valve bridge and a proportional relief valve. The check valve bridge includes a first check valve and a second check valve connected to their outlets, and a third check valve and a fourth check valve connected to their inlets. The outlet of the third check valve is connected to the inlet of the first check valve. The outlet of the fourth check valve is connected to the inlet of the second check valve. Port A of the multi-way valve is connected between the first and third check valves. Port B of the multi-way valve is connected between the second and fourth check valves. The inlet of the proportional relief valve is connected to the outlet of the first check valve. The outlet of the proportional relief valve is connected to the inlet of the third check valve.

Description

Technical Field

[0001] This invention relates to the field of hydraulic excavator technology, and more specifically, to a real-time operating condition load simulation system for a hydraulic excavator power system. Background Technology

[0002] Hybrid power, pure electric drive, and distributed electro-hydraulic systems are among the various technologies applied in different types of machinery. Performance evaluation of these innovative systems is crucial for reducing R&D costs and time, as it avoids expensive field testing. However, traditional evaluation methods rely on load testing in real-world working environments, consuming significant human and material resources and making it difficult to quickly and efficiently complete a comprehensive performance evaluation of the power system before the machine leaves the factory. Therefore, simplifying load testing methods and replacing field testing with load simulation has become an urgent need to improve R&D efficiency and reduce costs.

[0003] In existing technologies, a common load simulation method uses a proportional relief valve instead of an actuator cylinder. A preset load spectrum is converted into a control signal and applied to the proportional relief valve, achieving simple pressure loading at the outlet of a multi-way valve. This approach reduces the size of the test system and avoids complex field operations, but it relies on pre-collecting load data under fixed operating conditions. Specifically, it statically applies the load spectrum to pressure valve control to simulate the magnitude of the load pressure, but ignores the dynamic interaction between flow and pressure in actual engineering machinery operation.

[0004] This existing method has a significant drawback: it cannot respond to the dynamic flow-pressure coupling characteristics of the excavator during operation. In actual operation, the system output flow rate and load pressure have a complex coupling relationship, resulting in drastic pressure changes under different flow rates. Static loading methods only simulate pressure magnitude and cannot reproduce this dynamic behavior. Consequently, the test results of load simulation are disconnected from the actual operation of the machine, reducing the accuracy and reliability of performance evaluation and failing to provide a reliable testing basis for the power system of construction machinery. Summary of the Invention

[0005] The present invention provides a real-time operating condition load simulation system for a hydraulic excavator power system to improve at least one of the above-mentioned technical problems.

[0006] To address the aforementioned technical problems, this invention provides a real-time operating condition load simulation system for a hydraulic excavator power system, comprising an excavator power system, a load-loading hydraulic system, a vehicle control unit connected to the load-loading hydraulic system, and a co-simulation system connected to the vehicle control unit.

[0007] The excavator power system includes an oil tank, a main pump and a pilot pump connected to the oil tank, a pilot hydraulic control handle connected to the pilot pump, a signal control valve connected to the pilot hydraulic control handle, and a multi-way valve connected to the main pump and the signal control valve.

[0008] The load-loading hydraulic system includes a check valve bridge integrated with the multi-way valve and a proportional relief valve integrated with the check valve bridge. The check valve bridge includes a first check valve and a second check valve connected to their outlets, and a third check valve and a fourth check valve connected to their inlets. The outlet of the third check valve is connected to the inlet of the first check valve. The outlet of the fourth check valve is connected to the inlet of the second check valve.

[0009] Port A of the multi-way valve is connected between the first and third check valves. Port B of the multi-way valve is connected between the second and fourth check valves.

[0010] The inlet of the proportional relief valve is connected to the outlet of the first check valve. The outlet of the proportional relief valve is connected to the inlet of the third check valve.

[0011] As a further optimization, the load-loading hydraulic system also includes a first flow sensor and a first pressure sensor connected to port A, and a second flow sensor and a second pressure sensor connected to port B.

[0012] The vehicle control unit is communicatively connected to the first flow sensor, the second flow sensor, the first pressure sensor, the second pressure sensor, the first check valve, the second check valve, the third check valve, the fourth check valve, and the proportional relief valve.

[0013] As a further optimization, the joint simulation system includes a vehicle software control platform and a dynamics simulation calculation software platform. The dynamics simulation calculation software platform includes an excavator hydraulic system simulation module, an excavator kinematics system simulation module, and a soil resistance simulation module.

[0014] The vehicle software control platform is used to analyze the analog electrical signals from the first one-way valve, the second one-way valve, the third one-way valve, and the fourth one-way valve of the vehicle control unit, and send the analyzed signal results to the dynamic simulation calculation software platform.

[0015] The dynamics simulation software platform is used to simulate the actual operation of the excavator. Specifically, the excavator hydraulic system simulation module simulates the excavator's hydraulic drive system. The excavator kinematics system simulation module simulates the excavator's mechanical structure and movements. The soil resistance simulation module simulates real soil to simulate the application of soil loads and sends the pressure of the cylinder drive chamber in the excavator hydraulic system simulation module to the vehicle software control platform in real time.

[0016] The dynamics simulation software platform sends the simulation results to the vehicle software control platform. The vehicle software control platform converts the simulation results into control parameters and sends them to the vehicle control unit. The vehicle control unit then controls the load-loading hydraulic system to achieve information interaction and control between the simulation and the hardware.

[0017] As a further optimization, the vehicle software control platform converts the load pressure signal into control parameters for the proportional relief valve and sends them to the vehicle control unit.

[0018] The vehicle control unit is used to receive analog electrical signals from the first flow sensor, the second flow sensor, the first pressure sensor, and the second pressure sensor in the load loading hydraulic system, and send them to the vehicle software control platform. At the same time, it receives control parameters from the vehicle software control platform and sends control signals to the proportional relief valve to adjust the valve core opening of the proportional relief valve, thereby controlling the inlet pressure of the proportional relief valve to achieve load loading at the load end.

[0019] As a further optimization, the vehicle control unit and the vehicle software control platform are connected via a CAN bus using Peak-CAN.

[0020] The vehicle software control platform and the dynamics simulation calculation software platform are connected via a co-simulation interface.

[0021] The vehicle control unit uses a proportional-integral-derivative (PI-DI) algorithm for closed-loop control of the proportional relief valve, calculating the error between the current cylinder pressure and the proportional relief valve inlet pressure obtained in the simulation. The proportional part adjusts based on the current error, the integral part eliminates the steady-state error of the system, and the derivative part predicts and corrects the error trend, enabling real-time adjustment of the proportional relief valve's control current to further refine the valve core opening and ensure that its inlet pressure matches the target loading pressure.

[0022] As a further optimization, the multi-way valve is provided with a control port, an oil inlet, an oil outlet, port A, and port B. The multi-way valve is configured such that the control port can control the oil inlet to switch between being connected to one of port A and port B. The port A or port B that is not connected to the oil inlet can switch to being connected to the oil outlet. The control port is connected to the signal control valve. The oil inlet is connected to the main pump. The oil outlet is connected to the oil tank.

[0023] As a further optimization, when the excavator's bucket is in the retracted working condition, oil is discharged from port A of the multi-way valve and returned from port B, and the proportional relief valve is loaded with pressure equal to the excavator's rodless chamber drive pressure.

[0024] At this time, the excavator's power system is operating. The drive motor drives the main pump and pilot pump to draw oil from the oil tank and output oil to the multi-way valve and pilot hydraulic control handle, respectively. The drive oil circuit outputs from port A of the multi-way valve, then passes through the first flow sensor and the first check valve in the check valve bridge to the proportional relief valve. The oil then flows through the proportional relief valve, through the fourth check valve and the second flow sensor to port B of the multi-way valve, returning to the oil tank.

[0025] During system operation, the vehicle control unit collects the current signals fed back by the first pressure sensor and the first flow sensor in real time, and sends them to the vehicle software control platform via the CAN bus using Peak-CAN.

[0026] The vehicle software control platform converts the received CAN message into the current cylinder drive flow and sends it to the excavator hydraulic system simulation module in the dynamic simulation calculation software platform through the co-simulation interface.

[0027] The excavator hydraulic system simulation module transmits the hydraulic parameters of the system at this time to the excavator kinematic system simulation module to control the excavator mechanical model to perform simulated motion.

[0028] The soil resistance simulation module simulates real soil resistance and applies it to the excavator kinematics system simulation module to simulate the application of soil resistance load and obtain the bucket cylinder pressure of the excavator hydraulic system simulation module at this time.

[0029] The dynamics simulation software platform sends the simulated bucket cylinder pressure results to the vehicle software control platform via a co-simulation interface. The vehicle software control platform converts the cylinder pressure parameters obtained from the dynamics simulation software platform into control current parameters for the proportional relief valve, and then uses Peak-CAN to send the cylinder pressure and proportional relief valve control current parameters to the vehicle control unit via the CAN bus.

[0030] The vehicle control unit receives the cylinder pressure from the vehicle software control platform as the target pressure and uses the first pressure sensor as feedback pressure for proportional-integral-derivative (PI-DI) algorithm control. It calculates the error between the current cylinder pressure (solved in the co-simulation system) and the proportional relief valve inlet pressure. 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 trend, enabling real-time adjustment of the proportional relief valve's control current. This further adjusts the current value sent by the vehicle control unit's PWM generator port to control the proportional relief valve's spool opening and adjust its inlet pressure, thus completing the load loading of the excavator's power system.

[0031] As a further optimization, when the excavator's bucket is in the outward tilting condition, oil is discharged from port B of the multi-way valve and returned from port A, and the proportional relief valve is loaded with pressure equal to the excavator's rod chamber drive pressure.

[0032] At this time, the excavator's power system is running. The drive motor drives the main pump and pilot pump to draw oil from the oil tank and output oil to the multi-way valve and pilot hydraulic control handle respectively. The drive oil circuit outputs from port B of the multi-way valve, and then passes through the second flow sensor and the second check valve in the check valve bridge to the proportional relief valve. The oil then passes through the proportional relief valve and flows through the third check valve and the first flow sensor to port A of the multi-way valve to return oil to the oil tank.

[0033] During system operation, the vehicle control unit collects the current signals from the second pressure sensor, the second flow sensor, and the feedback signal in real time, and sends them to the vehicle software control platform via the CAN bus using Peak-CAN.

[0034] The vehicle software control platform converts the received CAN message into the current cylinder drive flow and sends it to the excavator hydraulic system simulation module in the dynamic simulation calculation software platform through the co-simulation interface.

[0035] The excavator hydraulic system simulation module transmits the hydraulic parameters of the system at this time to the excavator kinematic system simulation module to control the simulated motion of the excavator mechanical model.

[0036] The soil resistance simulation module simulates real soil resistance and applies it to the excavator kinematics system simulation module to simulate the application of soil resistance load and obtain the bucket cylinder pressure of the excavator hydraulic system simulation module at this time.

[0037] The dynamics simulation software platform sends the simulated bucket cylinder pressure results to the vehicle software control platform via a co-simulation interface. The vehicle software control platform converts the cylinder pressure parameters obtained from the dynamics simulation software platform into control current parameters for the proportional relief valve, and then uses Peak-CAN to send the cylinder pressure and proportional relief valve control current parameters to the vehicle control unit via the CAN bus.

[0038] The vehicle control unit takes the cylinder pressure received from the vehicle software control platform as the target pressure, uses the first pressure sensor as feedback pressure, and performs proportional-integral-derivative algorithm control. It calculates the error between the current cylinder pressure and the inlet pressure of the proportional relief valve solved in the joint simulation system. 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, so that the control current of the proportional relief valve is adjusted in real time. Furthermore, the current value sent by the PWM generation port of the vehicle control unit is adjusted to control the valve core opening of the proportional relief valve and adjust its inlet pressure, thus completing the load loading of the excavator power system.

[0039] As a further optimization, the excavator's power system also includes a drive motor. The drive motor is mechanically connected to the main pump via a splined bushing, and the main pump drives the pilot pump through gear transmission.

[0040] As a further optimization, the proportional relief valve is a pilot-operated proportional relief valve.

[0041] By adopting the above technical solution, the present invention can achieve the following technical effects:

[0042] This embodiment presents a real-time operating condition load simulation system for a hydraulic excavator's power system, which is a unique semi-physical hydraulic load real-time loading system. It establishes a real-time interactive system between a simulation model of the excavator system and the actual excavator power system. By utilizing a simulated soil resistance model to obtain the cylinder pressure caused by the actual excavation load resistance, it applies real-time pressure loading to the proportional relief valve. This ensures that the load responds to the flow rate of the entire excavator during actual operation, guaranteeing the dynamic characteristics of actuator flow rate, pressure, and coupling during the actual measurement of the entire machine. Attached Figure Description

[0043] 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.

[0044] Figure 1 This is a schematic diagram of the structure of a real-time operating condition load simulation system.

[0045] Figure 2 This is a structural schematic diagram of working condition one.

[0046] Figure 3 This is a structural schematic diagram of working condition two.

[0047] The diagram is labeled as follows: 1-Excavator power system, 2-Load loading hydraulic system, 3-Vehicle control unit, 4-Co-simulation system, 11-Pilot hydraulic control handle, 12-Signal control valve, 13-Multi-way valve, 14-Drive motor, 15-Main pump, 16-Pilot pump, 17-Oil tank, 21-First flow sensor, 22-Second flow sensor, 23-First pressure sensor, 24-Second pressure sensor, 25-Check valve bridge, 251-First check valve, 252-Second check valve, 253-Third check valve, 254-Fourth check valve, 26-Pilot-operated proportional relief valve, 41-Vehicle software control platform, 42-Dynamics simulation calculation software platform, 421-Excavator hydraulic system simulation module, 422-Excavator kinematics system simulation module, 423-Soil resistance simulation module. Detailed Implementation

[0048] 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.

[0049] Please see Figures 1 to 3 The first embodiment of the present invention provides a real-time working condition load simulation system for a hydraulic excavator power system, which includes an excavator power system 1, a load loading hydraulic system 2, a vehicle control unit 3 connected to the load loading hydraulic system 2, and a co-simulation system 4 connected to the vehicle control unit 3.

[0050] The excavator power system 1 includes an oil tank 17, a main pump 15 and a pilot pump 16 connected to the oil tank 17, a pilot hydraulic control handle 11 connected to the pilot pump 16, a signal control valve 12 connected to the pilot hydraulic control handle 11, and a multi-way valve 13 connected to the main pump 15 and the signal control valve 12. Preferably, the excavator power system 1 also includes a drive motor 14. The 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 through gear transmission. The main pump 15 supplies oil to the multi-way valve 13. The signal control valve 12 provides secondary pilot pressure to control the opening degree of each valve port inside the multi-way valve 13.

[0051] The load-loading hydraulic system 2 includes a one-way valve bridge 25 connected to the multi-way valve 13 and a proportional relief valve connected to the one-way valve bridge 25.

[0052] The one-way valve bridge 25 includes a first one-way valve 251 and a second one-way valve 252 connected to the outlet, and a third one-way valve 253 and a fourth one-way valve 254 connected to the inlet. The outlet of the third one-way valve 253 is connected to the inlet of the first one-way valve 251. The outlet of the fourth one-way valve 254 is connected to the inlet of the second one-way valve 252.

[0053] Port A of multi-way valve 13 is connected between the first check valve 251 and the third check valve 253. Port B of multi-way valve 13 is connected between the second check valve 252 and the fourth check valve 254.

[0054] The inlet of the proportional relief valve is connected to the outlet of the first check valve 251. The outlet of the proportional relief valve is connected to the inlet of the third check valve 253.

[0055] Based on the above embodiments, in an optional embodiment of the present invention, such as Figures 1 to 3 As shown, the load loading hydraulic system 2 also includes a first flow sensor 21 and a first pressure sensor 23 connected to port A, and a second flow sensor 22 and a second pressure sensor 24 connected to port B.

[0056] The vehicle control unit 3 is communicatively connected to the first flow sensor 21, the second flow sensor 22, the first pressure sensor 23, the second pressure sensor 24, the first one-way valve 251, the second one-way valve 252, the third one-way valve 253, the fourth one-way valve 254, and the proportional relief valve.

[0057] The hydraulic load simulation system in this embodiment converts a preset load force into a corresponding proportional relief valve control current to drive the valve core opening of the proportional relief valve, thereby controlling the valve inlet pressure of the proportional relief valve to achieve loading. Based on the above embodiment, in an optional embodiment of the present invention, the proportional relief valve is a pilot-operated proportional relief valve 26. The pilot-operated proportional relief valve 26 has a built-in maximum pressure protection device, enabling overflow return oil to protect the system safety when the system pressure is too high.

[0058] The hydraulic cylinders of an excavator allow bidirectional flow, while the proportional relief valve only allows unidirectional flow. This embodiment uses a one-way valve bridge 25 to solve the problem caused by changes in the flow direction of the hydraulic fluid at the outlet of the multi-way valve 13 due to changes in operating conditions.

[0059] Specifically, in the hydraulic pipeline connection structure of this embodiment, the main pump 15 and the pilot pump 16 are connected to the oil tank 17 through hydraulic pipes to draw oil. The main pump 15 is connected to the multi-way valve 13 to supply oil to the multi-way valve 13. The pilot pump 16 is connected to the pilot hydraulic control handle 11 to supply oil to the pilot hydraulic control handle 11. The pilot hydraulic control handle 11 is connected to the signal control valve 12. The signal control valve 12 is connected to the multi-way valve 13. The signal control valve 12 provides secondary pilot pressure to control the opening degree of each valve port inside the multi-way valve 13. The hydraulic pipeline connection method of the one-way valve bridge 25 is as follows: the outlet of the first one-way valve 251 is connected to the outlet of the second one-way valve 252; the inlet of the second one-way valve 252 is connected to the outlet of the fourth one-way valve 254; the inlet of the third one-way valve 253 is connected to the inlet of the fourth one-way valve 254; and the outlet of the third one-way valve 253 is connected to the inlet of the first one-way valve 251. The A pipeline of the outlet of the multi-way valve 13 is connected to the middle of the first one-way valve 251 and the third one-way valve 253 via a tee. The B pipeline of the outlet of the multi-way valve 13 is connected to the middle of the second one-way valve 252 and the fourth one-way valve 254 via a tee. The hydraulic pipelines of the first flow sensor 21 and the second flow sensor 22 are connected to the A and B pipelines of the multi-way valve 13 and the one-way valve bridge 25, respectively. At the same time, the first pressure sensor 23 and the second pressure sensor 24 are connected to the A and B pipelines respectively via tee connections.

[0060] This embodiment provides a real-time working condition load simulation system for a hydraulic excavator power system. The system uses a load loading hydraulic system 2 to replace the actuator cylinders on the original excavator. It combines the vehicle control unit 3 and the simulation system 4 to simulate real soil load and achieve pressure control of the proportional relief valve, thereby loading the excavator system with load.

[0061] The co-simulation system 4 includes a vehicle software control platform 41 and a dynamics simulation calculation software platform 42. The dynamics simulation calculation software platform 42 includes an excavator hydraulic system simulation module 421, an excavator kinematics system simulation module 422, and a soil resistance simulation module 423.

[0062] The vehicle software control platform 41 is used to analyze the analog electrical signals from the first one-way valve 251, the second one-way valve 252, the third one-way valve 253, and the fourth one-way valve 254 of the vehicle control unit 3, and send the analyzed signal results to the dynamic simulation calculation software platform 42.

[0063] The dynamics simulation software platform 42 is used to simulate the actual operation of the excavator. Among them, the excavator hydraulic system simulation module 421 simulates the excavator's hydraulic drive system. The excavator kinematics system simulation module 422 simulates the excavator's mechanical structure and movements. The soil resistance simulation module 423 simulates real soil to simulate the application of soil load and sends the pressure of the cylinder drive chamber in the excavator hydraulic system simulation module 421 to the vehicle software control platform 41 in real time.

[0064] The dynamics simulation software platform 42 sends the simulation results to the vehicle software control platform 41. The vehicle software control platform 41 converts the simulation results into control parameters and sends them to the vehicle control unit 3. The vehicle control unit 3 then controls the load-loading hydraulic system 2 to achieve information interaction and control between the simulation and the hardware.

[0065] Preferably, the vehicle software control platform 41 and the dynamics simulation calculation software platform 42 are connected via a co-simulation interface. Specifically, in this embodiment, the dynamics simulation calculation software platform 42 and the vehicle software control platform 41 are co-simulated using the co-simulation interface. The dynamics simulation calculation software platform 42 sends the simulation results to the vehicle software control platform 41 through the simulation interface. The vehicle software control platform 41 converts the simulation results into control parameters and sends them to the vehicle control unit 3 via the CAN bus. The vehicle control unit 3 then controls the load-loading hydraulic system 2, ultimately achieving information interaction and control between the simulation and the hardware. The simulation software described above is used in this embodiment, but is not limited to the software mentioned herein.

[0066] In the co-simulation system 4, real-time animations can be added, and simulation results are obtained by receiving real-time flow signals from the hardware system. The operator can view the real-time actions of the excavator under control based on the animations; that is, any test condition can be achieved through the operator's operation.

[0067] Furthermore, considering the impact of additional pressure generated during the operation of complex hydraulic systems on the inlet pressure of the proportional relief valve, closed-loop control of the proportional relief valve is added to the control strategy. Specifically, the vehicle control unit 3 uses a proportional-integral-derivative algorithm for closed-loop control of the proportional relief valve, calculating the error between the current cylinder pressure and the proportional relief valve inlet pressure obtained in the simulation. 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 trend of error change, enabling real-time adjustment of the control current of the proportional relief valve to further adjust the valve core opening of the proportional relief valve, ensuring that its inlet pressure matches the target loading pressure.

[0068] It should be noted that the semi-physical load simulation loading system of this embodiment is not limited to load loading of excavators, but is applicable to any construction machinery that uses hydraulically driven work actuators.

[0069] In this embodiment of the invention, the excavator power system 1 provides hydraulic flow to the load-loading hydraulic system 2. During system operation, the drive motor 14 drives the main pump 15 and pilot pump 16 to output flow. When the operator operates the pilot hydraulic control handle 11, it outputs pilot control flow to the signal control valve 12. The signal control valve 12 outputs a corresponding action control flow signal to the multi-way valve 13 based on the input flow from the pilot hydraulic control handle 11. The multi-way valve 13 then outputs drive flow to the load-loading hydraulic system 2. A first flow sensor 21 is used to detect the flow rate at port A of the multi-way valve 13. A first pressure sensor 23 is used to detect the pressure at port A of the multi-way valve 13. A second flow sensor 22 is used to detect the flow rate at port B of the multi-way valve 13. A second pressure sensor 24 is used to detect the pressure at port B of the multi-way valve 13. The one-way valve bridge 25 is used to ensure that the outlet flow of the multi-way valve 13 reaches the inlet of the pilot-operated proportional relief valve 26. The pilot-operated proportional relief valve 26 adjusts the valve core opening by receiving the control electrical signal from the vehicle control unit 3 to apply pressure to the one-way valve bridge 25 for load loading.

[0070] In this embodiment of the invention, the vehicle control unit 3 receives analog electrical signals from the first flow sensor 21, the second flow sensor 22, the first pressure sensor 23, and the second pressure sensor 24 in the load-loading hydraulic system 2, and sends them to the vehicle software control platform 41. Simultaneously, it receives control parameters from the vehicle software control platform 41 and sends control signals to the pilot-operated proportional relief valve 26 to adjust the inlet pressure of the pilot-operated proportional relief valve 26 to achieve load loading. Specifically, in this embodiment, the first flow sensor 21, the second flow sensor 22, the first pressure sensor 23, and the second pressure sensor 24 are electrically connected to the vehicle control unit 3, and send their respective collected current and current signals to the analog signal receiving port of the vehicle control unit 3. The vehicle control unit 3 is electrically connected to the pilot-operated proportional relief valve 26, and sends control current signals through the PWM generation port on the vehicle control unit 3 to control the valve core opening of the pilot-operated proportional relief valve 26, thereby adjusting the inlet pressure of the pilot-operated proportional relief valve 26.

[0071] In the co-simulation system 4 of this invention, the vehicle software control platform 41 is used to parse the analog electrical signals from the first one-way valve 251, the second one-way valve 252, the third one-way valve 253, and the fourth one-way valve 254 of the vehicle control unit 3, and send the parsed signal results to the dynamic simulation calculation software platform 42 through the co-simulation interface.

[0072] The dynamic simulation calculation software platform 42 in the co-simulation system 4 of this embodiment of the invention is used to simulate the actual operation of the excavator. The excavator hydraulic system simulation module 421 is used to simulate the hydraulic drive system of the excavator, the excavator kinematic system simulation module 422 is used to simulate the mechanical structure and movement of the excavator, and the soil resistance simulation module 423 simulates real soil to simulate the application of soil load. The pressure of the cylinder drive chamber in the excavator hydraulic system simulation module 421 is sent to the vehicle software control platform 41 in real time through the co-simulation interface.

[0073] The vehicle software control platform 41 converts the load pressure signal into control electrical signal parameters for the pilot-operated proportional relief valve 26 and sends them to the vehicle control unit 3. The vehicle control unit 3 converts the received control parameters into control electrical signals to control the valve core opening of the pilot-operated proportional relief valve 26, thereby controlling the inlet pressure of the pilot-operated proportional relief valve 26.

[0074] In this embodiment, the connection scheme for the communication line is as follows: the vehicle control unit 3 communicates with the vehicle software control platform 41 via the CAN bus using Peak-CAN. Specifically, the vehicle software control platform 41 converts the results of the joint simulation with the dynamics simulation calculation software platform 42 into control signals for the pilot-operated proportional relief valve 26, and sends them to the vehicle control unit 3 via the CAN bus using Peak-CAN.

[0075] In this embodiment, the information interaction on the co-simulation system 4 is as follows: During simulation, the excavator hydraulic system simulation module 421 in the dynamics simulation software platform 42 transmits the hydraulic parameters of the system at this time of operation to the excavator kinematics system simulation module 422 to control the simulated motion of the excavator mechanical model. The soil resistance simulation module 423 simulates the actual soil resistance acting on the excavator kinematics system simulation module 422 to simulate the application of soil resistance load. The dynamics simulation software platform 42 sends the pressure results of each cylinder drive chamber at this time to the vehicle software control platform 41 through the co-simulation interface.

[0076] The multi-way valve 13 is provided with a control port, an oil inlet, an oil outlet, an A port (i.e., connection port A), and a B port (i.e., connection port B). The multi-way valve 13 is configured such that the control port can control the oil inlet to switch between being connected to one of the A port and the B port. The A port or B port not connected to the oil inlet is switched to be connected to the oil outlet. 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 17.

[0077] The bucket digging load is the most typical load during excavation operations. The following description uses bucket cylinder load as an example. It includes two working conditions: bucket retraction and bucket unloading, but is not limited to these conditions.

[0078] like Figure 2 As shown, when the excavator's bucket is in the retracted working condition, oil is discharged from port A of the multi-way valve 13 and returned from port B. The pilot-operated proportional relief valve 26 is loaded with pressure equal to the excavator's rodless chamber drive pressure.

[0079] At this time, the excavator's power system 1 is operating. The drive motor 14 drives the main pump 15 and the pilot pump 16 to draw oil from the oil tank 17 and output oil to the multi-way valve 13 and the pilot hydraulic control handle 11, respectively. The drive oil circuit outputs from port A of the multi-way valve 13, and then passes through the first flow sensor 21 and the first check valve 251 in the check valve bridge 25 to the pilot-operated proportional relief valve 26. Then, the oil passing through the pilot-operated proportional relief valve 26 flows through the fourth check valve 254 and the second flow sensor 22 to port B of the multi-way valve 13 to return oil to the oil tank 17.

[0080] When the system is running, the vehicle control unit 3 collects the current signals fed back by the first pressure sensor 23 and the first flow sensor 21 in real time, and sends them to the vehicle software control platform 41 via the CAN bus using Peak-CAN.

[0081] The parsing program written in the vehicle software control platform 41 converts the received CAN message into the current cylinder drive flow and sends it to the excavator hydraulic system simulation module 421 in the dynamic simulation calculation software platform 42 through the co-simulation interface.

[0082] The excavator hydraulic system simulation module 421 transmits the hydraulic parameters of the system at this time to the excavator kinematic system simulation module 422 to control the excavator mechanical model to perform simulated motion.

[0083] The soil resistance simulation module 423 simulates real soil resistance and acts on the excavator kinematics system simulation module 422 to simulate the application of soil resistance load and obtain the bucket cylinder pressure of the excavator hydraulic system simulation module 421 at this time.

[0084] The dynamics simulation software platform 42 sends the simulated pressure result of the bucket cylinder to the vehicle software control platform 41 via the co-simulation interface. The vehicle software control platform 41 converts the cylinder pressure parameters obtained from the dynamics simulation software platform 42 into control current parameters for the pilot-operated proportional relief valve 26, and uses Peak-CAN to send the cylinder pressure and control current parameters of the pilot-operated proportional relief valve 26 to the vehicle control unit 3 via the CAN bus.

[0085] The vehicle control unit 3 uses the cylinder pressure received from the vehicle software control platform 41 as the target pressure, and uses the first pressure sensor 23 as the feedback pressure to perform proportional-integral-derivative algorithm control. It calculates the error between the current cylinder pressure and the proportional relief valve inlet pressure, as solved in the co-simulation system 4. The proportional part adjusts based on the current error, the integral part eliminates the steady-state error of the system, and the derivative part predicts and corrects the error trend, enabling real-time adjustment of the control current of the pilot-operated proportional relief valve 26. Furthermore, it adjusts the current value sent by the PWM generator port of the vehicle control unit 3 to control the valve core opening of the pilot-operated proportional relief valve 26, adjusting its inlet pressure to complete the load loading of the excavator power system 1.

[0086] like Figure 3 As shown, when the excavator's bucket is in the outward tilting condition, oil is discharged from port B of the multi-way valve 13 and returned from port A. The pilot-operated proportional relief valve 26 is loaded with pressure equal to the excavator's rod chamber drive pressure.

[0087] At this time, the excavator power system 1 is running. The drive motor 14 drives the main pump 15 and the pilot pump 16 to draw oil from the oil tank 17 and output oil to the multi-way valve 13 and the pilot hydraulic control handle 11 respectively. The drive oil circuit outputs from port B of the multi-way valve 13, and then passes through the second flow sensor 22 and the second check valve 252 in the check valve bridge 25 to the pilot proportional relief valve 26. The oil then passes through the pilot proportional relief valve 26 and flows through the third check valve 253 and the first flow sensor 21 to port A of the multi-way valve 13 to return oil to the oil tank 17.

[0088] When the system is running, the vehicle control unit 3 collects the current signals from the second pressure sensor 24 and the second flow sensor 22 in real time, and sends them to the vehicle software control platform 41 via the CAN bus using Peak-CAN.

[0089] The parsing program written in the vehicle software control platform 41 converts the received CAN message into the current cylinder drive flow and sends it to the excavator hydraulic system simulation module 421 in the dynamic simulation calculation software platform 42 through the co-simulation interface.

[0090] The excavator hydraulic system simulation module 421 transmits the hydraulic parameters of the system at this time to the excavator kinematic system simulation module 422 to control the simulated motion of the excavator mechanical model.

[0091] The soil resistance simulation module 423 simulates real soil resistance and acts on the excavator kinematics system simulation module 422 to simulate the application of soil resistance load and obtain the bucket cylinder pressure of the excavator hydraulic system simulation module 421 at this time.

[0092] The dynamics simulation software platform 42 sends the simulated pressure result of the bucket cylinder to the vehicle software control platform 41 via the co-simulation interface. The vehicle software control platform 41 converts the cylinder pressure parameters obtained from the dynamics simulation software platform 42 into control current parameters for the pilot-operated proportional relief valve 26, and uses Peak-CAN to send the cylinder pressure and control current parameters of the pilot-operated proportional relief valve 26 to the vehicle control unit 3 via the CAN bus.

[0093] The vehicle control unit 3 takes the cylinder pressure received from the vehicle software control platform 41 as the target pressure, and uses the first pressure sensor 23 as the feedback pressure to perform proportional-integral-derivative algorithm control. It calculates the error between the current cylinder pressure and the inlet pressure of the proportional relief valve solved in the co-simulation system 4. 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, so that the control current of the pilot proportional relief valve 26 is adjusted in real time. The current value sent by the PWM generation port of the vehicle control unit 3 is further adjusted to control the valve core opening of the pilot proportional relief valve 26 to adjust its inlet pressure, thereby completing the load loading of the excavator power system 1.

[0094] This embodiment presents a real-time operating condition load simulation system for a hydraulic excavator's power system, which is a unique semi-physical hydraulic load real-time loading system. It establishes a real-time interactive system between a simulation model of the excavator system and the actual excavator power system. By utilizing a simulated soil resistance model to obtain the cylinder pressure caused by the actual excavation load resistance, it applies real-time pressure loading to the proportional relief valve. This ensures that the load responds to the flow rate of the entire excavator during actual operation, guaranteeing the dynamic characteristics of actuator flow rate, pressure, and coupling during the actual measurement of the entire machine.

[0095] This embodiment constructs a semi-physical load loading system for an excavator using a physical power system, a load loading system, and a co-simulation system 4. This solves the problem that traditional hydraulic loading platforms, which use static curve load loading, cannot reproduce the complex coupling relationship between pressure and flow during actual excavator operation. This semi-physical hydraulic real-time load loading system calculates the actual load and applies it to the proportional relief valve on the hydraulic load loading module in real time through a co-simulation model. This achieves precise loading of the excavator power system 1, ensuring the coupling relationship between flow and load pressure during load loading. It can respond to the actual load based on the output flow of the excavator system, improving the accuracy and reliability of load loading. This provides a reliable testing system for testing the entire machine power system before the excavator leaves the factory.

[0096] This embodiment takes into account the impact of the additional pressure from the complex hydraulic system on the pressure loading end of the proportional relief valve. By setting the load result of the simulation model as the target pressure and the pressure at the inlet of the proportional relief valve, a proportional-integral-derivative algorithm is used for control, which further improves the accuracy and reliability of load loading.

[0097] 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 real-time operating condition load simulation system for a hydraulic excavator power system, characterized in that, The system includes an excavator power system, a load-loading hydraulic system, a vehicle control unit connected to the load-loading hydraulic system, and a co-simulation system connected to the vehicle control unit. The excavator power system includes an oil tank, a main pump and a pilot pump connected to the oil tank, a pilot hydraulic control handle connected to the pilot pump, a signal control valve connected to the pilot hydraulic control handle, and a multi-way valve connected to the main pump and the signal control valve. The load-loading hydraulic system includes a check valve bridge connected to the multi-way valve and a proportional relief valve connected to the check valve bridge; the check valve bridge includes a first check valve and a second check valve connected to the outlet, and a third check valve and a fourth check valve connected to the inlet; the outlet of the third check valve is connected to the inlet of the first check valve; the outlet of the fourth check valve is connected to the inlet of the second check valve. Port A of the multi-way valve is connected between the first check valve and the third check valve; Port B of the multi-way valve is connected between the second check valve and the fourth check valve. The inlet of the proportional relief valve is connected to the outlet of the first check valve; the outlet of the proportional relief valve is connected to the inlet of the third check valve. The load-loading hydraulic system also includes a first flow sensor and a first pressure sensor connected to port A, and a second flow sensor and a second pressure sensor connected to port B; The vehicle control unit is communicatively connected to the first flow sensor, the second flow sensor, the first pressure sensor, the second pressure sensor, the first check valve, the second check valve, the third check valve, the fourth check valve, and the proportional relief valve. The joint simulation system includes a vehicle software control platform and a dynamics simulation calculation software platform; the dynamics simulation calculation software platform includes an excavator hydraulic system simulation module, an excavator kinematics system simulation module, and a soil resistance simulation module; The vehicle software control platform is used to analyze the analog electrical signals from the first one-way valve, the second one-way valve, the third one-way valve, and the fourth one-way valve of the vehicle control unit, and send the analyzed signal results to the dynamic simulation calculation software platform. The dynamic simulation software platform is used to simulate the actual operation of the excavator; among them, the excavator hydraulic system simulation module is used to simulate the hydraulic drive system of the excavator; the excavator kinematic system simulation module is used to simulate the mechanical structure and movement of the excavator; the soil resistance simulation module is used to simulate real soil to simulate the application of soil load, and sends the pressure of the cylinder drive chamber in the excavator hydraulic system simulation module to the vehicle software control platform in real time. The dynamics simulation software platform sends the simulation results to the vehicle software control platform; the vehicle software control platform converts the simulation results into control parameters and sends them to the vehicle control unit, which then controls the load-loading hydraulic system to achieve information interaction and control between the simulation and the hardware.

2. The real-time operating condition load simulation system for a hydraulic excavator power system according to claim 1, characterized in that, The vehicle software control platform converts the load pressure signal into control parameters for the proportional relief valve and sends them to the vehicle control unit. The vehicle control unit is used to receive analog electrical signals from the first flow sensor, the second flow sensor, the first pressure sensor, and the second pressure sensor in the load loading hydraulic system, and send them to the vehicle software control platform. At the same time, it receives control parameters from the vehicle software control platform and sends control signals to the proportional relief valve to adjust the valve core opening of the proportional relief valve, thereby controlling the inlet pressure of the proportional relief valve to achieve load loading at the load end.

3. The real-time operating condition load simulation system for a hydraulic excavator power system according to claim 1, characterized in that, The vehicle control unit and the vehicle software control platform are connected via Peak-CAN through a CAN bus. The vehicle software control platform and the dynamics simulation calculation software platform are connected via a co-simulation interface. The vehicle control unit uses a proportional-integral-derivative algorithm for closed-loop control of the proportional relief valve, calculating the error between the current cylinder pressure and the inlet pressure of the proportional relief valve obtained in the simulation. 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, so that the control current of the proportional relief valve is adjusted in real time to further adjust the valve core opening of the proportional relief valve so that its inlet pressure is consistent with the target loading pressure.

4. A real-time operating condition load simulation system for a hydraulic excavator power system according to any one of claims 1 to 3, 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 multi-way valve is configured such that the control port can control the oil inlet to switch between being connected to one of the A port and the B port; the A port and the B port that are not connected to the oil inlet can switch between being connected to the oil outlet; 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.

5. A real-time operating condition load simulation system for a hydraulic excavator power system according to claim 4, characterized in that, When the excavator's bucket is in the retracted working condition, oil is discharged from port A of the multi-way valve and returned from port B. The proportional relief valve is loaded with pressure equal to the excavator's rodless chamber drive pressure. At this time, the excavator's power system is running. The drive motor drives the main pump and pilot pump to draw oil from the oil tank and output oil to the multi-way valve and pilot hydraulic control handle respectively. The drive oil circuit outputs from port A of the multi-way valve, and then passes through the first flow sensor and the first check valve in the check valve bridge to the proportional relief valve. Then, the oil passing through the proportional relief valve flows through the fourth check valve and the second flow sensor to port B of the multi-way valve to return oil to the oil tank. During system operation, the vehicle control unit collects the current signals fed back by the first pressure sensor and the first flow sensor in real time, and sends them to the vehicle software control platform via the CAN bus using Peak-CAN. The vehicle software control platform converts the received CAN message into the current cylinder drive flow and sends it to the excavator hydraulic system simulation module in the dynamic simulation calculation software platform through the co-simulation interface; The excavator hydraulic system simulation module transmits the hydraulic parameters of the system at this time to the excavator kinematic system simulation module in order to control the excavator mechanical model to perform simulated motion. The soil resistance simulation module simulates real soil resistance and applies it to the excavator kinematics system simulation module to simulate the application of soil resistance load and obtain the bucket cylinder pressure of the excavator hydraulic system simulation module at this time. The dynamic simulation software platform sends the simulated pressure results of the bucket cylinder to the vehicle software control platform through the co-simulation interface. The vehicle software control platform converts the cylinder pressure parameters obtained from the dynamic simulation calculation software platform into the control current parameters of the proportional relief valve, and uses Peak-CAN to send the cylinder pressure and the control current parameters of the proportional relief valve to the vehicle control unit via the CAN bus. The vehicle control unit takes the cylinder pressure received from the vehicle software control platform as the target pressure, uses the first pressure sensor as feedback pressure, and performs proportional-integral-derivative algorithm control to calculate the error between the current cylinder pressure and the inlet pressure of the proportional relief valve solved in the joint simulation system. 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, so that the control current of the proportional relief valve is adjusted in real time. The current value sent by the PWM generation port of the vehicle control unit is further adjusted to control the valve core opening of the proportional relief valve and adjust its inlet pressure, thus completing the load loading of the excavator power system.

6. The real-time operating condition load simulation system for a hydraulic excavator power system according to claim 4, characterized in that, When the excavator's bucket is in the outward tilting condition, oil is discharged from port B of the multi-way valve and returned from port A. The proportional relief valve is loaded with pressure equal to the excavator's rod chamber drive pressure. At this time, the excavator's power system is running. The drive motor drives the main pump and pilot pump to draw oil from the oil tank and output oil to the multi-way valve and pilot hydraulic control handle respectively. The drive oil circuit outputs from port B of the multi-way valve, and then passes through the second flow sensor and the second check valve in the check valve bridge to the proportional relief valve. The oil then passes through the proportional relief valve and flows through the third check valve and the first flow sensor to port A of the multi-way valve to return oil to the oil tank. During system operation, the vehicle control unit collects the feedback current signals from the second pressure sensor, the second flow sensor, and uses Peak-CAN to send them to the vehicle software control platform via the CAN bus. The vehicle software control platform converts the received CAN message into the current cylinder drive flow and sends it to the excavator hydraulic system simulation module in the dynamic simulation calculation software platform through the co-simulation interface; The excavator hydraulic system simulation module transmits the hydraulic parameters of the system at this time to the excavator kinematic system simulation module in order to control the simulated motion of the excavator mechanical model; The soil resistance simulation module simulates real soil resistance and applies it to the excavator kinematics system simulation module to simulate the application of soil resistance load and obtain the bucket cylinder pressure of the excavator hydraulic system simulation module at this time. The dynamic simulation software platform sends the simulated pressure results of the bucket cylinder to the vehicle software control platform through the co-simulation interface. The vehicle software control platform converts the cylinder pressure parameters obtained from the dynamic simulation calculation software platform into the control current parameters of the proportional relief valve, and uses Peak-CAN to send the cylinder pressure and the control current parameters of the proportional relief valve to the vehicle control unit via the CAN bus. The vehicle control unit takes the cylinder pressure received from the vehicle software control platform as the target pressure, uses the first pressure sensor as feedback pressure, and performs proportional-integral-derivative algorithm control. It calculates the error between the current cylinder pressure and the inlet pressure of the proportional relief valve solved in the joint simulation system. 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, so that the control current of the proportional relief valve is adjusted in real time. Furthermore, the current value sent by the PWM generation port of the vehicle control unit is adjusted to control the valve core opening of the proportional relief valve and adjust its inlet pressure, thus completing the load loading of the excavator power system.

7. A real-time operating condition load simulation system for a hydraulic excavator power system according to any one of claims 1 to 3, characterized in that, The excavator power system also includes a drive motor; the drive motor is mechanically connected to the main pump through a splined bushing, and the main pump drives the pilot pump to work through gear transmission.

8. A real-time operating condition load simulation system for a hydraulic excavator power system according to any one of claims 1 to 3, characterized in that, The proportional relief valve is a pilot-operated proportional relief valve.

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