Excavator arm energy recovery system based on pump motor and control method thereof

Abstract

This invention relates to the field of excavator technology and its control method, specifically a pump-motor-based excavator stick energy recovery system. The system includes a hydraulic cylinder, a reversible hydraulic pump motor, an integrated electric generator, a three-position four-way solenoid valve with a first inlet, a first outlet, a second outlet, and a first return port, a first hydraulic pump connected to a hydraulic tank, a first check valve connecting the hydraulic pump outlet and the first inlet, an electric motor, a third check valve connecting the first return port and a second pipeline interface of the reversible hydraulic pump motor, and a first two-position two-way solenoid valve connecting the pipeline between the third check valve and the second pipeline interface to the first inlet. Specifically, the first pipeline interface of the reversible hydraulic pump motor is connected to the hydraulic tank via a fourth check valve and the third two-position two-way solenoid valve, and is connected to the first return port via a pipeline connected to the second two-position two-way solenoid valve. The first outlet pipeline is connected to the rodless chamber of the hydraulic cylinder, and the second outlet is connected to the rod chamber via a pipeline.

Description

Technical Field

[0001] This invention relates to the field of excavator technology, and more specifically, to an excavator boom energy recovery system based on a pump motor and its control method. Background Technology

[0002] Excavators, as core equipment in the construction machinery field, are widely used in complex operation scenarios such as earthmoving, mining, and material handling. During the daily operation cycle of an excavator, the extension and retraction of the boom are extremely frequent, and the precision of its motion control and energy efficiency directly affect the overall machine performance. Currently, boom hydraulic systems generally use valve control to achieve speed regulation, that is, controlling the flow rate into the hydraulic cylinder through the throttling effect of a multi-way valve to match the speed requirements under different working conditions.

[0003] However, this traditional valve control method has significant inherent drawbacks. During the extension or retraction of the boom, when the output flow of the first hydraulic pump exceeds the required flow of the cylinder, the excess high-pressure oil flows back to the oil tank through the relief valve, directly converting hydraulic energy into heat energy. Even during the flow matching stage, the throttling effect of the valve orifice generates significant pressure loss, similarly causing energy to dissipate as heat. This heat is carried away by the hydraulic oil, leading to a sharp increase in oil temperature. Excessively high oil temperature significantly reduces the viscosity of the hydraulic oil, resulting in increased internal leakage in the system, sluggish operation of actuators, and abnormal vibration. Long-term operation will also accelerate the wear and aging of hydraulic components, seriously threatening the working stability and reliability of the excavator.

[0004] Therefore, existing excavator stick drive systems have significant shortcomings in energy utilization, and the problem of high overall machine energy consumption has remained unresolved for a long time. In particular, the potential energy contained in the stick under certain working conditions (such as deceleration or gravity descent) cannot be effectively recovered by existing systems, further exacerbating unnecessary energy waste. How to achieve precise flow matching and efficient recovery of dissipated energy from the perspectives of system architecture and energy management has become a critical technical bottleneck that urgently needs to be overcome in this field. Summary of the Invention

[0005] This invention provides an excavator boom energy recovery system and its control method based on a pump motor, aiming to improve at least one of the above-mentioned technical problems.

[0006] To solve the above-mentioned technical problems, the present invention provides an excavator stick energy recovery system based on a pump motor, which includes a hydraulic cylinder, a reversible hydraulic pump motor, an electric generator connected to the reversible hydraulic pump motor, a three-position four-way solenoid valve provided with a first oil inlet, a first oil outlet, a second oil outlet and a first oil return port, a first hydraulic pump whose hydraulic pump inlet is connected to a hydraulic oil tank, a first check valve connecting the hydraulic pump outlet and the first oil inlet, an electric motor connected to the first hydraulic pump, a third check valve connecting the first oil return port and a second pipeline interface of the reversible hydraulic pump motor, and a first two-position two-way solenoid valve for connecting the pipeline between the third check valve and the second pipeline interface to the first oil inlet.

[0007] The first pipeline interface of the reversible hydraulic pump motor is connected to the hydraulic oil tank via a fourth check valve and a third two-position two-way solenoid valve, and is connected to the first return port via a second two-position two-way solenoid valve. The first oil outlet is connected to the rodless chamber of the hydraulic cylinder, and the second oil outlet is connected to the rod chamber via a pipeline.

[0008] As a further optimization, the excavator stick energy recovery system based on the pump motor also includes a flow sensor connected between the rodless chamber of the hydraulic cylinder and the first outlet.

[0009] As a further optimization, the excavator boom energy recovery system based on the pump motor also includes a second check valve, a first relief valve, and a second relief valve.

[0010] The second check valve is connected between the first two-position two-way solenoid valve and the first oil inlet.

[0011] The first relief valve is connected between the first oil inlet and the hydraulic oil tank.

[0012] The second relief valve is used to connect the pipeline between the third check valve and the second pipeline interface to the hydraulic oil tank.

[0013] This application also provides a control method for an excavator stick energy recovery system based on a pump motor, used to control the excavator stick energy recovery system based on a pump motor as described in any part of the first aspect.

[0014] The control methods include S1 to S4.

[0015] S1. Acquire the operating voltage signal output by the operating handle, and compare the operating voltage signal with the preset mid-dead zone voltage range to obtain the current operating status. The operating status includes extended, retracted, and stopped.

[0016] S2. When the working state is extended, the first required flow rate of the rodless chamber is obtained according to the required extension speed. Based on the first required flow rate, the three-position four-way solenoid valve, the first two-position two-way solenoid valve, the second two-position two-way solenoid valve, the third two-position two-way solenoid valve, the electric motor, and the integrated electric generator are controlled. When the first required flow rate exceeds the maximum flow rate threshold, the oil outlets of the first hydraulic pump and the reversible hydraulic pump motor are connected to the rodless chamber, and the second two-position two-way solenoid valve is disconnected, so that the hydraulic cylinder forms a differential connection.

[0017] S3. When the working state is retracted, the second required flow rate of the rod cavity is obtained according to the required retraction speed, and the three-position four-way solenoid valve, the first two-position two-way solenoid valve, the second two-position two-way solenoid valve, the third two-position two-way solenoid valve, the motor and the integrated electric generator are controlled according to the second required flow rate.

[0018] S4. When the working status is stopped, close all solenoid valves, and the motor and generator will stop or maintain idle speed.

[0019] As a further optimization, the first demand traffic A first flow threshold is set. Second flow threshold and the third flow threshold Preferably, S2 specifically includes S21 to S25.

[0020] S21. Calculate the target extension speed of the excavator stick based on the effective amplitude of the working voltage signal deviating from the mid-range dead zone voltage threshold. Then, calculate the first required flow rate of the rodless chamber of the hydraulic cylinder based on the target extension speed. .

[0021] S22, when At this time, the reversible hydraulic pump motor is in hydraulic motor mode, and the integrated electric generator is in generator mode. The electric motor drives the first hydraulic pump to supply oil to the rodless chamber, and the hydraulic oil in the rod chamber drives the reversible hydraulic pump motor to drive the integrated electric generator to generate electricity. Then, the oil flows back to the oil tank through the third two-position two-way solenoid valve.

[0022] S23, when At this time, the reversible hydraulic pump motor is in hydraulic pump mode, used to deliver hydraulic oil from the rod chamber and hydraulic oil tank to the rodless chamber.

[0023] S24, when At this time, the reversible hydraulic pump motor is in hydraulic pump mode, used to deliver hydraulic oil from the rod chamber and hydraulic oil tank to the rodless chamber, while the first hydraulic pump supplies oil to the rodless chamber.

[0024] S25, when At this time, the second and third two-position two-way solenoid valves are disconnected, and the first two-position two-way solenoid valve is connected, so that the rod chamber of the hydraulic cylinder is unidirectionally connected to the rodless chamber. The first hydraulic pump supplies oil to the rodless chamber. The reversible hydraulic pump motor is in hydraulic pump mode, used to deliver hydraulic oil from the hydraulic oil tank to the rodless chamber.

[0025] As a further optimization, S22 specifically includes: when At this time, the first inlet of the three-position four-way solenoid valve is connected to the first outlet, and the second outlet is connected to the first return port. The third two-position two-way solenoid valve is activated, while the first and second two-position two-way solenoid valves are deactivated. The electric motor drives the first hydraulic pump to supply oil to the rodless chamber of the hydraulic cylinder, causing the hydraulic oil in the rod chamber to flow back to the reversible hydraulic pump motor, and then flow into the oil tank through the third two-position two-way solenoid valve. At this time, the reversible hydraulic pump motor is in motor mode, driving the integrated electric generator to power generation mode, and the generated electrical energy is fed back to the energy storage device.

[0026] As a further optimization, S23 specifically includes: when At this time, the first inlet of the three-position four-way solenoid valve is connected to the first outlet, and the second outlet is connected to the first return port. The first and second two-position two-way solenoid valves are activated, while the third two-position two-way solenoid valve is deactivated. The first hydraulic pump does not operate. The integrated electric generator drives the reversible hydraulic pump motor to supply oil to the rodless chamber of the hydraulic cylinder, causing the hydraulic oil in the rod chamber to flow back through the second two-position two-way solenoid valve to the inlet of the reversible hydraulic pump motor for replenishment.

[0027] As a further optimization, S24 specifically includes: when At this time, the first inlet of the three-position four-way solenoid valve is connected to the first outlet, and the second outlet is connected to the first return port. The first and second two-position two-way solenoid valves are activated, while the third two-position two-way solenoid valve is deactivated. The electric motor drives the first hydraulic pump to supply oil to the rodless chamber of the hydraulic cylinder, and the integrated electric generator drives the reversible hydraulic pump motor to simultaneously supply oil to the rodless chamber of the hydraulic cylinder through the first and second two-way solenoid valves. Meanwhile, the hydraulic oil in the rod chamber flows back to the inlet of the reversible hydraulic pump motor through the second two-position two-way solenoid valve for replenishment.

[0028] As a further optimization, S25 specifically includes: when At this time, the first inlet of the three-position four-way solenoid valve is connected to the first outlet, and the second outlet is connected to the first return port. The first two-position two-way solenoid valve is activated, while the second two-position two-way solenoid valve and the third two-position two-way solenoid valve are deactivated. The electric motor drives the first hydraulic pump to supply oil to the rodless chamber of the hydraulic cylinder. At the same time, the electric generator drives the reversible hydraulic pump motor to supply oil to the rodless chamber of the hydraulic cylinder through the first two-position two-way solenoid valve. At this time, the hydraulic oil in the rod chamber flows back to the main oil circuit through the third check valve and the first two-position two-way solenoid valve to form replenishment oil, that is, it flows to the rodless chamber of the hydraulic cylinder, so that the hydraulic cylinder can reach the maximum extension speed.

[0029] As a further optimization, when the excavator boom energy recovery system based on the pump motor is equipped with a flow sensor, step S2 also includes S26. S26: Based on the first required flow rate... Obtain the first target speed of the electric motor and the integrated electric generator, and drive the electric motor and the integrated electric generator. Obtain the actual flow signal from the flow sensor and compare it with the first required flow rate. The comparison is performed, and based on the comparison results, the first target speed is adjusted using a PID proportional-integral-derivative closed-loop control method to achieve flow closed-loop control.

[0030] As a further optimization, the second demand traffic A fourth flow threshold is set. and the fifth flow threshold Preferably, S3 specifically includes S31 to S34.

[0031] S31. Calculate the target retraction speed of the excavator stick based on the effective amplitude of the deviation of the working voltage signal from the mid-range dead zone voltage threshold. Then, calculate the second required flow rate of the rod chamber of the hydraulic cylinder based on the target retraction speed. .

[0032] S32, when At this time, the reversible hydraulic pump motor is in hydraulic motor mode, and the integrated electric generator is in generator mode. The electric motor drives the first hydraulic pump to supply oil to the rod chamber, and the hydraulic oil in the rodless chamber drives the reversible hydraulic pump motor to drive the integrated electric generator to generate electricity. Then, the oil flows back to the oil tank through the third two-position two-way solenoid valve.

[0033] S33, when At this time, the reversible hydraulic pump motor is in hydraulic pump mode, supplying oil to the rod chamber, while the hydraulic oil in the rodless chamber flows back to the hydraulic oil tank.

[0034] S34, when At this time, the reversible hydraulic pump motor is in hydraulic pump mode, supplying oil to the rod chamber, while the first hydraulic pump supplies oil to the rod chamber, and the hydraulic oil in the rodless chamber flows back to the hydraulic oil tank.

[0035] As a further optimization, S32 specifically includes: when At this time, the first inlet of the three-position four-way solenoid valve is connected to the second outlet, and the first outlet is connected to the first return port. The third two-position two-way solenoid valve is activated, while the first and second two-position two-way solenoid valves are deactivated. The electric motor drives the first hydraulic pump to supply oil to the rod chamber of the hydraulic cylinder, causing the hydraulic oil in the rodless chamber to flow back to the reversible hydraulic pump motor, and then flow into the oil tank through the third two-position two-way solenoid valve. At this time, the reversible hydraulic pump motor is in motor mode, driving the integrated electric generator in generator mode, and the generated electrical energy is fed back to the energy storage device.

[0036] As a further optimization, S33 specifically includes: when At this time, the first inlet of the three-position four-way solenoid valve is connected to the second outlet, and the first outlet is connected to the first return port. This activates the first two-position two-way solenoid valve, the second two-position two-way solenoid valve, and the third two-position two-way solenoid valve. The integrated electric generator drives the reversible hydraulic pump motor to supply oil to the rod chamber of the hydraulic cylinder. Part of the hydraulic oil in the rodless chamber replenishes the first pipeline interface of the reversible hydraulic pump motor, and part flows back to the hydraulic oil tank.

[0037] As a further optimization, S34 specifically includes: when At this time, the first inlet of the three-position four-way solenoid valve is connected to the second outlet, and the first outlet is connected to the first return port. This activates the first two-position two-way solenoid valve, the second two-position two-way solenoid valve, and the third two-position two-way solenoid valve. The electric motor drives the first hydraulic pump to supply oil to the rod chamber of the hydraulic cylinder, and the integrated electric generator drives the reversible hydraulic pump motor to simultaneously supply oil to the rod chamber of the hydraulic cylinder through the first two-position two-way solenoid valve, causing the hydraulic oil in the rodless chamber to flow back to the hydraulic tank.

[0038] As a further optimization, when the excavator boom energy recovery system based on the pump motor is equipped with a flow sensor, step S3 also includes S35. S35: Based on the second required flow rate... The system acquires the operating status and second target speed of the electric motor and generator, and drives the electric motor and generator. It also acquires the actual flow signal from the flow sensor and the second required flow rate. The comparison is performed, and based on the comparison results, the second target speed is adjusted using a PID proportional-integral-derivative closed-loop control method to achieve flow closed-loop control.

[0039] By adopting the above technical solution, the present invention can achieve the following technical effects:

[0040] This invention provides an excavator stick energy recovery system and its control method based on a pump motor, which effectively solves the problems of high energy loss, high oil temperature, and decreased system reliability caused by throttling and overflow in traditional excavator stick valve control systems. This invention achieves efficient energy recovery and reuse by introducing a reversible hydraulic pump motor and an integrated electric generator, along with the coordinated control of multiple solenoid valves.

[0041] Specifically, when the required flow rate for stick extension or retraction is low, the system can convert the hydraulic oil in the return chamber of the hydraulic cylinder into mechanical energy, which is then used to generate electricity and store it, thus recovering the energy that would otherwise be wasted through the relief valve. When the required flow rate increases, the system can flexibly switch operating modes, such as switching the reversible hydraulic pump motor to pump mode to participate in oil supply, or supplying oil together with the main hydraulic pump, or even forming a differential connection between the two chambers of the cylinder when maximum speed is required, thereby achieving precise flow matching over a wide flow range and significantly reducing throttling losses. In addition, PID closed-loop control based on flow sensors further improves the flow control accuracy and system dynamic response performance. In summary, this invention reduces system energy consumption and heat generation from the source, improving energy utilization efficiency and the stability and reliability of the entire machine. Attached Figure Description

[0042] 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.

[0043] Figure 1 This is a schematic diagram of the excavator boom energy recovery system.

[0044] The markings in the diagram are: 1-Hydraulic oil tank, 2-First hydraulic pump, 3-Electric motor, 4-First check valve, 5-First relief valve, 6-Three-position four-way solenoid valve, 7-Flow sensor, 8-Hydraulic cylinder, 9-Second check valve, 10-First two-position two-way solenoid valve, 11-Third check valve, 12-Second two-position two-way solenoid valve, 13-Second relief valve, 14-Reversible hydraulic pump motor, 15-Fourth check valve, 16-Electric generator, 17-Third two-position two-way solenoid valve. Detailed Implementation

[0045] 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.

[0046] Depend on Figure 1 As shown, this embodiment of the invention provides an excavator stick energy recovery system based on a pump motor, which includes a hydraulic cylinder 8, a reversible hydraulic pump motor 14, an electric generator 16 driven to the reversible hydraulic pump motor 14, a three-position four-way solenoid valve 6 provided with a first oil inlet, a first oil outlet, a second oil outlet and a first oil return port, a first hydraulic pump 2 whose hydraulic pump inlet is connected to a hydraulic oil tank 1, a first check valve 4 connecting the hydraulic pump outlet and the first oil inlet, an electric motor 3 driven to the first hydraulic pump 2, a third check valve 11 connecting the first oil return port and the second pipeline interface of the reversible hydraulic pump motor 14, and a first two-position two-way solenoid valve 10 for connecting the pipeline between the third check valve 11 and the second pipeline interface to the first oil inlet.

[0047] The first pipeline interface of the reversible hydraulic pump motor 14 is connected to the hydraulic oil tank 1 via the fourth check valve 15 and the third two-position two-way solenoid valve 17, and is connected to the first return port via the second two-position two-way solenoid valve 12. The first oil outlet is connected to the rodless chamber of the hydraulic cylinder 8, and the second oil outlet is connected to the rod chamber via a pipeline.

[0048] Specifically, the excavator stick energy recovery system based on a pump motor and its control method includes a hydraulic oil tank 1, a first hydraulic pump 2, an electric motor 3, a three-position four-way solenoid valve 6, a flow sensor 7, a hydraulic cylinder 8, a first two-position two-way solenoid valve 10, a second two-position two-way solenoid valve 12, a third two-position two-way solenoid valve 17, a reversible hydraulic pump motor 14, and an integrated electric generator 16. The hydraulic cylinder 8 drives the excavator stick to extend / retract. The output shaft of the electric motor 3 is connected to the first hydraulic pump 2 to drive its operation.

[0049] The inlet pipe of the first hydraulic pump 2 is connected to the hydraulic oil tank 1. The outlet pipe of the first hydraulic pump 2 is connected to the first inlet of the three-position four-way solenoid valve 6 and the first working port of the first two-position two-way solenoid valve 10. The first outlet pipe of the three-position four-way solenoid valve 6 is connected to the rodless chamber of the hydraulic cylinder 8. The second outlet pipe of the three-position four-way solenoid valve 6 is connected to the rod chamber of the hydraulic cylinder 8. The return pipe of the three-position four-way solenoid valve 6 is connected to the second working port of the first two-position two-way solenoid valve 10, the first working port of the second two-position two-way solenoid valve 12, and the second pipe port of the reversible hydraulic pump motor 14. The output shaft of the electric generator 16 is driven to the reversible hydraulic pump motor 14 to drive the reversible hydraulic pump motor 14.

[0050] When the reversible hydraulic pump motor 14 is in motor mode, it drives the integrated electric generator 16 to power generation mode. The first pipeline interface of the reversible hydraulic pump motor 14 is connected to the second working interface of the second two-position two-way solenoid valve 12 and the hydraulic oil tank 1.

[0051] The first two-position two-way solenoid valve 10, the second two-position two-way solenoid valve 12, and the third two-position two-way solenoid valve 17 are all without vent ports. When the control terminal of the first two-position two-way solenoid valve 10 is energized, its first and second working interfaces are connected, allowing oil to pass through. When the control terminal of the second two-position two-way solenoid valve 12 is energized, its first and second working interfaces are connected, allowing oil to pass through. When the control terminal of the third two-position two-way solenoid valve 17 is energized, its first and second working interfaces are connected, allowing oil to pass through.

[0052] In this embodiment, when the control terminal of the solenoid valve is de-energized, the first two-position two-way solenoid valve 10, the second two-position two-way solenoid valve 12, and the third two-position two-way solenoid valve 17 are in the off state.

[0053] The three-position four-way solenoid valve 6 has a structure without an exhaust port. For example... Figure 1 As shown, when the three-position four-way solenoid valve 6 is in the left position, the first oil inlet is connected to the first oil outlet, and the first return oil outlet is connected to the second oil outlet. When the three-position four-way solenoid valve 6 is in the right position, the first oil inlet is connected to the second oil outlet, and the first return oil outlet is connected to the first oil outlet. When the three-position four-way directional valve is in the neutral position, the first oil inlet, the first return oil outlet, the first oil outlet, and the oil outlet are mutually blocked, meaning that oil cannot pass through.

[0054] As a further optimization, the excavator stick energy recovery system based on the pump motor also includes a flow sensor 7 connected between the rodless chamber of the hydraulic cylinder 8 and the first oil outlet. Specifically, such as... Figure 1 As shown, the flow sensor 7 is connected to the rodless chamber of the hydraulic cylinder 8 to obtain the actual flow signal of the rodless chamber of the hydraulic cylinder 8.

[0055] As a further optimization, the excavator boom energy recovery system based on the pump motor also includes a second check valve 9, a first relief valve 5, and a second relief valve 13. The second check valve 9 is connected between the first two-position two-way solenoid valve 10 and the first oil inlet. The first relief valve 5 is connected between the first oil inlet and the hydraulic oil tank 1. The second relief valve 13 is used to connect the pipeline between the third check valve 11 and the second pipeline interface to the hydraulic oil tank 1.

[0056] The inlet pipe of the first check valve 4 is connected to the outlet pipe of the first hydraulic pump 2. The outlet pipe of the first check valve 4 is connected to the inlet pipe of the first relief valve 5. The first check valve 4 is configured to prevent oil from flowing back into the first hydraulic pump 2 and causing a shock when the first two-position two-way solenoid valve 10 is turned on.

[0057] The inlet pipe of the second check valve 9 is connected to the first working port of the first two-position two-way solenoid valve 10. The outlet pipe of the second check valve 9 is connected to the first inlet port of the three-position four-way solenoid valve 6. The second check valve 9 is configured to prevent oil from flowing back into the reversible hydraulic pump motor 14 and causing a shock when the first two-position two-way solenoid valve 10 is turned on.

[0058] The inlet pipe of the third check valve 11 is connected to the first working port of the second two-position two-way solenoid valve 12 and the first return port of the three-position four-way solenoid valve 6. The outlet pipe of the third check valve 11 is connected to the second working port of the first two-position two-way solenoid valve 10 and the second pipe port of the reversible hydraulic pump motor 14. The third check valve 11 is configured to prevent oil from flowing into the lever chamber of the hydraulic cylinder 8 and to prevent oil from flowing back into the reversible hydraulic pump motor 14 and causing impact when the reversible hydraulic pump motor 14 is in the oil supply condition.

[0059] The inlet pipe of the fourth check valve 15 is connected to the hydraulic cylinder 8. The outlet pipe of the fourth check valve 15 is connected to the first pipe interface of the reversible hydraulic pump motor 14. The fourth check valve 15 is configured to prevent oil from flowing into the hydraulic cylinder 8 when the second two-position two-way solenoid valve 12 is turned on.

[0060] The outlet pipe of the first relief valve 5 is connected to the hydraulic oil tank 1. The first relief valve 5 is configured to open when the hydraulic oil pressure in the pipe connecting the outlet of the first hydraulic pump 2 and the inlet of the three-position four-way solenoid valve 6 exceeds a preset threshold, so as to limit the maximum working pressure of the hydraulic system.

[0061] The inlet pipe of the second relief valve 13 is connected to the outlet pipe of the reversible hydraulic pump motor 14. The outlet pipe of the second relief valve 13 is connected to the hydraulic oil tank 1. The second relief valve 13 is configured to open when the hydraulic oil pressure in the pipe connecting the outlet of the reversible hydraulic pump motor 14 and the second working interface of the first two-position two-way solenoid valve 10 exceeds a preset threshold, thereby limiting the maximum working pressure of the hydraulic system.

[0062] In this embodiment of the invention, the reversible hydraulic pump motor 14 refers to a hydraulic component that can both act as a hydraulic pump to convert mechanical energy into hydraulic energy to deliver oil externally, and as a hydraulic motor to convert hydraulic energy into mechanical energy to output torque externally. The electric generator integrated machine 16 refers to a motor that can both act as an electric motor 3 to convert electrical energy into mechanical energy to drive a load, and as a generator to convert mechanical energy into electrical energy to charge an energy storage device. The three-position four-way solenoid valve 6 is an electromagnetically controlled directional valve with three working positions and four oil ports (first inlet, first outlet, second outlet, and first return port), which controls the flow direction of hydraulic oil by changing the position of the valve core. The first hydraulic pump 2 and the second hydraulic pump are both fixed displacement pumps, meaning that the output flow rate is constant when the speed is constant. The combined use of the above components enables the system to flexibly switch energy transmission paths under different operating conditions, providing a hardware foundation for precise flow matching and energy recovery.

[0063] This application also provides a control method for an excavator stick energy recovery system based on a pump motor, used to control the aforementioned excavator stick energy recovery system based on a pump motor. The control method of this invention for an excavator stick energy recovery system based on a reversible hydraulic pump motor 14 relies on an electric motor 3 to drive the extension / retraction movement. Through the control of the first hydraulic pump 2, the reversible hydraulic pump motor 14, and the oil circuit, the excavator reduces overall energy consumption, increases energy utilization, and achieves energy recovery. This control method is particularly suitable for energy-saving and emission-reducing excavators.

[0064] The control components of the control method include a vehicle controller and an operating handle. The operating handle is electrically connected to the signal input terminal of the vehicle controller.

[0065] The control methods include S1 to S4.

[0066] S1. Acquire the operating voltage signal output by the operating handle, and compare the operating voltage signal with the preset mid-dead zone voltage range to obtain the current operating status. The operating status includes extended, retracted, and stopped.

[0067] Specifically, the vehicle controller acquires the operating voltage signal output by the control handle and compares this signal with a preset dead-zone voltage range to determine the current operating status.

[0068] When the working voltage signal is greater than the preset upper limit of the dead zone voltage (corresponding to the forward push of the operating handle), the vehicle controller determines that the excavator stick extension request state is currently in effect, and the system executes subsequent steps A1 to A4.

[0069] When the operating voltage signal is less than the preset lower limit of the mid-dead zone voltage (corresponding to the operation handle being pulled back), the vehicle controller determines that it is currently in the state of excavator stick retraction request, and the system executes subsequent steps B1 to B4.

[0070] When the working voltage signal is within the preset dead zone voltage range (i.e., the handle is not operated or slightly accidentally touched), the vehicle controller determines that it is in a stopped state. At this time, it controls all motors 3 to maintain idle speed or stop, and controls all solenoid valves to close.

[0071] S2. When the working state is extended, the first required flow rate of the rodless chamber is obtained according to the required extension speed. Based on the first required flow rate, the three-position four-way solenoid valve 6, the first two-position two-way solenoid valve 10, the second two-position two-way solenoid valve 12, the third two-position two-way solenoid valve 17, the electric motor 3, and the integrated electric generator 16 are controlled. When the first required flow rate exceeds the maximum flow rate threshold, the oil outlets of the first hydraulic pump 2 and the reversible hydraulic pump motor 14 are connected to the rodless chamber, and the second two-position two-way solenoid valve 12 is disconnected, so that the hydraulic cylinder 8 forms a differential connection.

[0072] S3. When the working state is retracted, the second required flow rate of the rod cavity is obtained according to the required retraction speed, and the three-position four-way solenoid valve 6, the first two-position two-way solenoid valve 10, the second two-position two-way solenoid valve 12, the third two-position two-way solenoid valve 17, the motor 3 and the integrated electric generator 16 are controlled according to the second required flow rate.

[0073] S4. When the working status is stopped, close all solenoid valves, and the motor 3 and the integrated electric generator 16 stop or maintain idle speed.

[0074] Based on the above embodiments, in an optional embodiment of the present invention, the first demand flow rate... A first flow threshold is set. Second flow threshold and the third flow threshold Preferably, S2 specifically includes S21 to S25.

[0075] S21. Calculate the target extension speed of the excavator stick based on the effective amplitude of the working voltage signal deviating from the mid-range dead zone voltage threshold. Then, calculate the first required flow rate of the rodless chamber of hydraulic cylinder 8 based on the target extension speed. .

[0076] Specifically, the vehicle controller acquires the effective amplitude of the voltage signal deviating from the median dead zone voltage threshold and calculates the target movement speed of the boom hydraulic cylinder. Subsequently, the vehicle controller determines the required flow rate of the rodless chamber of the hydraulic cylinder 8 based on the target movement speed. The vehicle controller will control the flow rate of the rodless chamber of hydraulic cylinder 8. Each with the first flow threshold Second flow threshold Third flow threshold Comparison:

[0077] S22, when At this time, the reversible hydraulic pump motor 14 is in hydraulic motor mode, and the electric generator integrated machine 16 is in generator mode. The electric motor 3 drives the first hydraulic pump 2 to supply oil to the rodless chamber, and the hydraulic oil in the rod chamber drives the reversible hydraulic pump motor 14 to drive the electric generator integrated machine 16 to generate electricity, and then flows back to the oil tank through the third two-position two-way solenoid valve 17.

[0078] Preferably, when At this time, the first oil inlet of the three-position four-way solenoid valve 6 is connected to the first oil outlet, and the second oil outlet is connected to the first oil return port. The third two-position two-way solenoid valve 17 is turned on, while the first two-position two-way solenoid valve 10 and the second two-position two-way solenoid valve 12 are not turned on. The motor 3 drives the first hydraulic pump 2 to supply oil to the rodless chamber of the hydraulic cylinder 8, causing the hydraulic oil in the rod chamber to flow back to the reversible hydraulic pump motor 14, and then flow into the oil tank through the third two-position two-way solenoid valve 17. At this time, the reversible hydraulic pump motor 14 is in motor mode, driving the electric generator 16 to power generation mode, and the generated electrical energy is fed back to the energy storage device.

[0079] S23, when At this time, the reversible hydraulic pump motor 14 is in hydraulic pump mode, used to deliver hydraulic oil from the rod chamber and hydraulic oil tank 1 to the rodless chamber.

[0080] Preferably, when At this time, the first oil inlet of the three-position four-way solenoid valve 6 is connected to the first oil outlet, and the second oil outlet is connected to the first oil return port. The first two-position two-way solenoid valve 10 and the second two-position two-way solenoid valve 12 are activated, while the third two-position two-way solenoid valve 17 is deactivated. The first hydraulic pump 2 does not work. The electric generator 16 drives the reversible hydraulic pump motor 14 to supply oil to the rodless chamber of the hydraulic cylinder 8, so that the hydraulic oil in the rod chamber flows back to the oil inlet of the reversible hydraulic pump motor 14 through the second two-position two-way solenoid valve 12 for replenishment.

[0081] S24, when At this time, the reversible hydraulic pump motor 14 is in hydraulic pump mode, used to deliver hydraulic oil from the rod chamber and hydraulic oil tank 1 to the rodless chamber, while the first hydraulic pump 2 supplies oil to the rodless chamber.

[0082] Preferably, when At this time, the first inlet of the three-position four-way solenoid valve 6 is connected to the first outlet, and the second outlet is connected to the first return port. The first two-position two-way solenoid valve 10 and the second two-position two-way solenoid valve 12 are activated, while the third two-position two-way solenoid valve 17 is deactivated. The electric motor 3 drives the first hydraulic pump 2 to supply oil to the rodless chamber of the hydraulic cylinder 8, and the electric generator 16 drives the reversible hydraulic pump motor 14 to simultaneously supply oil to the rodless chamber of the hydraulic cylinder 8 through the first two-position two-way solenoid valve 10. Meanwhile, the hydraulic oil in the rod chamber flows back to the inlet of the reversible hydraulic pump motor 14 through the second two-position two-way solenoid valve 12 for replenishment.

[0083] S25, when At this time, the second two-position two-way solenoid valve 12 and the third two-position two-way solenoid valve 17 are disconnected, and the first two-position two-way solenoid valve 10 is connected, so that the rod chamber of the hydraulic cylinder 8 is unidirectionally connected to the rodless chamber. The first hydraulic pump 2 supplies oil to the rodless chamber. The reversible hydraulic pump motor 14 is in hydraulic pump mode, used to deliver hydraulic oil from the hydraulic oil tank 1 to the rodless chamber.

[0084] Preferably, when At this time, the first inlet of the three-position four-way solenoid valve 6 is connected to the first outlet, and the second outlet is connected to the first return port. The first two-position two-way solenoid valve 10 is activated, while the second two-position two-way solenoid valve 12 and the third two-position two-way solenoid valve 17 are deactivated. The electric motor 3 drives the first hydraulic pump 2 to supply oil to the rodless chamber of the hydraulic cylinder 8. At the same time, the electric generator 16 drives the reversible hydraulic pump motor 14 to supply oil to the rodless chamber of the hydraulic cylinder 8 through the first two-position two-way solenoid valve 10. At this time, the hydraulic oil in the rod chamber flows back to the main oil circuit through the third check valve 11 and the first two-position two-way solenoid valve 10 to form replenishment oil, that is, it flows to the rodless chamber of the hydraulic cylinder 8 so that the hydraulic cylinder can reach the maximum extension speed.

[0085] Specifically, in S25, the hydraulic oil flowing out of the rod chamber of the hydraulic cylinder 8 can only flow to the rodless chamber. At this time, the hydraulic oil in the rodless chamber has three sources: one is the first hydraulic pump 2, one is the reversible hydraulic pump motor 14, and one is the rod chamber. At this time, the flow rate into the rodless chamber reaches the maximum, and the extension speed of the hydraulic cylinder 8 reaches the maximum.

[0086] It should be noted that when hydraulic oil is transferred from the rod chamber to the rodless chamber, forming a differential connection, although the extension speed of the hydraulic rod increases, the thrust of the hydraulic rod decreases due to the increased pressure of the hydraulic oil in the rod chamber. Therefore, the rapid extension of S25 is usually manually operated by the operator when no load or low load is detected, requiring rapid extension and retraction. At this time, the extension speed reaches its maximum, but the thrust of the hydraulic rod is not significant.

[0087] In the above control method, by setting a first flow threshold, a second flow threshold, and a third flow threshold, and dividing the first required flow of the rodless chamber of the hydraulic cylinder 8 into multiple intervals, the system can automatically select the optimal working mode according to the actual flow demand. When the flow demand is low, the reversible hydraulic pump motor 14 drives the integrated electric generator 16 to generate electricity, achieving energy recovery. When the flow demand is medium, the reversible hydraulic pump motor 14 switches to pump mode, coordinating with or independently supplying oil to the first hydraulic pump 2, reducing throttling losses. When the flow demand is high, differential connection allows oil from the rod chamber to be replenished to the rodless chamber, achieving rapid extension without increasing the displacement of the first hydraulic pump 2. This hierarchical control strategy effectively avoids the energy waste caused by single throttling adjustment in traditional valve control systems, while improving the system's response speed and adaptability to operating conditions.

[0088] Based on the above embodiments, in an optional embodiment of the present invention, when the excavator boom energy recovery system based on the pump motor is equipped with a flow sensor 7, step S2 further includes S26. S26: Based on the first required flow rate... The first target speed of motor 3 and integrated electric generator 16 is obtained, and motor 3 and integrated electric generator 16 are driven. The actual flow signal of flow sensor 7 is obtained and compared with the first required flow rate. The comparison is performed, and based on the comparison results, the first target speed is adjusted using a PID proportional-integral-derivative closed-loop control method to achieve flow closed-loop control.

[0089] In this embodiment, the first hydraulic pump 2 is a fixed displacement pump. The reversible hydraulic pump motor 14 is also a fixed displacement pump when in hydraulic pump mode. Furthermore, the displacement of the reversible hydraulic pump motor 14 is greater than the displacement of the first hydraulic pump 2.

[0090] Specifically, the vehicle controller sends speed control signals to the first motor controller and the second motor controller to control the speeds of the electric motor 3 and the integrated electric generator 16, respectively. During this process, the displacement of the first hydraulic pump 2 and the reversible hydraulic pump motor 14 remains constant. The output system flow rate changes with the speed of the electric motor 3. The actual flow rate signal of the rodless chamber of the hydraulic cylinder 8 is acquired and sent to the vehicle controller. The vehicle controller calculates and adjusts the speeds of the first and second motor controllers, thereby changing the loop flow rate and achieving closed-loop control of the loop flow rate.

[0091] When performing closed-loop control of the excavator's stick, a PID proportional-integral-derivative closed-loop control system is used for the extended stick. PID control uses the proportional term (P) to quickly respond to errors, the integral term (I) to eliminate steady-state errors, and the derivative term (D) to predict error trends, thus achieving more precise control. Even when the excavator stick exhibits a certain degree of nonlinearity or parameter variations, PID control maintains good control performance. In scenarios where the excavator stick is extended, PID control ensures that the stick moves accurately at the predetermined speed and position, while reducing overshoot and oscillation, improving the system's response speed and control accuracy. Through appropriate parameter adjustments, the PID controller can adapt to different operating conditions and performance requirements, achieving efficient and reliable excavator stick control.

[0092] Through its own closed-loop control, the system can not only respond quickly to local changes but also ensure optimal overall system performance. This reduces system fluctuations and enhances system robustness and stability.

[0093] In this invention, by adding a flow sensor 7 and employing a PID closed-loop control method, the system can monitor the actual flow rate of the rodless chamber of the hydraulic cylinder 8 in real time, compare it with the target required flow rate, and dynamically adjust the speed of the electric motor 3 and the integrated electric generator 16. Since both the first hydraulic pump 2 and the reversible hydraulic pump motor 14 are fixed displacement pumps, their output flow rate is proportional to the drive speed. Therefore, precise flow control can be achieved by adjusting the speed. The PID controller uses the proportional term to quickly respond to flow deviations, the integral term to eliminate steady-state errors, and the derivative term to suppress overshoot and oscillations, thereby achieving high-precision and high-stability flow matching during the stick extension process. This closed-loop control structure not only further reduces throttling losses but also significantly improves the smoothness of stick movement and control accuracy.

[0094] Based on the above embodiments, in an optional embodiment of the present invention, the second demand flow... A fourth flow threshold is set. and the fifth flow threshold Preferably, S3 specifically includes S31 to S34.

[0095] S31. Calculate the target retraction speed of the excavator stick based on the effective amplitude of the deviation of the working voltage signal from the mid-range dead zone voltage threshold. Then, calculate the second required flow rate of the rod chamber of hydraulic cylinder 8 based on the target retraction speed. .

[0096] Specifically, the vehicle controller acquires the effective amplitude of the voltage signal deviating from the median dead zone voltage threshold and calculates the target movement speed of the boom hydraulic cylinder. Subsequently, the vehicle controller determines the required flow rate in the rod chamber of the hydraulic cylinder 8 based on the target movement speed. The vehicle controller will control the flow rate in the rod chamber of hydraulic cylinder 8. respectively with the fourth flow threshold Fifth flow threshold Compare them.

[0097] S32, when At this time, the reversible hydraulic pump motor 14 is in hydraulic motor mode, and the electric generator integrated machine 16 is in generator mode. The electric motor 3 drives the first hydraulic pump 2 to supply oil to the rod chamber, and the hydraulic oil in the rodless chamber drives the reversible hydraulic pump motor 14 to drive the electric generator integrated machine 16 to generate electricity, and then flows back to the oil tank through the third two-position two-way solenoid valve 17.

[0098] Preferably, when At this time, the first oil inlet of the three-position four-way solenoid valve 6 is connected to the second oil outlet, and the first oil outlet is connected to the first oil return port. The third two-position two-way solenoid valve 17 is activated, while the first two-position two-way solenoid valve 10 and the second two-position two-way solenoid valve 12 are deactivated. The electric motor 3 drives the first hydraulic pump 2 to supply oil to the rod chamber of the hydraulic cylinder 8, causing the hydraulic oil in the rodless chamber to flow back to the reversible hydraulic pump motor 14, and then flow into the oil tank through the third two-position two-way solenoid valve 17. At this time, the reversible hydraulic pump motor 14 is in motor mode, driving the electric generator 16 to power generation mode, and the generated electrical energy is fed back to the energy storage device.

[0099] S33, when At this time, the reversible hydraulic pump motor 14 is in hydraulic pump mode, supplying oil to the rod chamber, while the hydraulic oil in the rodless chamber flows back to the hydraulic oil tank 1.

[0100] Preferably, when At this time, the first inlet of the three-position four-way solenoid valve 6 is connected to the second outlet, and the first outlet is connected to the first return port. The first two-position two-way solenoid valve 10, the second two-position two-way solenoid valve 12, and the third two-position two-way solenoid valve 17 are activated. The integrated electric generator 16 drives the reversible hydraulic pump motor 14 to supply oil to the rod chamber of the hydraulic cylinder 8. Part of the hydraulic oil in the rodless chamber replenishes the first pipeline interface of the reversible hydraulic pump motor 14, and part flows back to the hydraulic oil tank 1. At this time, the first hydraulic pump 2 is not operating.

[0101] S34, when At this time, the reversible hydraulic pump motor 14 is in hydraulic pump mode, supplying oil to the rod chamber, while the first hydraulic pump 2 supplies oil to the rod chamber, and the hydraulic oil in the rodless chamber flows back to the hydraulic oil tank 1.

[0102] Preferably, when At this time, the first oil inlet of the three-position four-way solenoid valve 6 is connected to the second oil outlet, and the first oil outlet is connected to the first oil return port. The first two-position two-way solenoid valve 10, the second two-position two-way solenoid valve 12, and the third two-position two-way solenoid valve 17 are activated. The electric motor 3 drives the first hydraulic pump 2 to supply oil to the rod chamber of the hydraulic cylinder 8, and the electric generator 16 drives the reversible hydraulic pump motor 14 to simultaneously supply oil to the rod chamber of the hydraulic cylinder 8 through the first two-position two-way solenoid valve 10, so that part of the hydraulic oil in the rodless chamber is replenished to the first pipeline interface of the reversible hydraulic pump motor 14, and part flows back to the hydraulic oil tank 1.

[0103] During the stick retraction operation, this invention also sets a fourth and fifth flow threshold based on the second required flow rate of the rod chamber of hydraulic cylinder 8 to achieve graded control. When the required flow rate for retraction is low, the system introduces the high-pressure oil discharged from the rodless chamber into the reversible hydraulic pump motor 14, making it work in motor mode and drive the integrated electric generator 16 to generate electricity, thus completing energy recovery. When the required flow rate is moderate, the integrated electric generator 16 drives the reversible hydraulic pump motor 14 as a pump to supply oil to the rod chamber. Part of the oil in the rodless chamber is returned to the pump inlet, and part flows back to the oil tank, reducing the energy consumption of the main pump. When the required flow rate is high, the first hydraulic pump 2 and the reversible hydraulic pump motor 14 simultaneously supply oil to the rod chamber to ensure the retraction speed. This control strategy enables the retraction process to also have the ability to accurately match energy recovery and flow rate, effectively reducing the energy loss of the entire machine during the stick retraction action.

[0104] Based on the above embodiments, in an optional embodiment of the present invention, when the excavator boom energy recovery system based on the pump motor is equipped with a flow sensor 7, step S3 further includes S35. S35: According to the second required flow rate... The system acquires the operating status and second target speed of motor 3 and integrated electric generator 16, and drives motor 3 and integrated electric generator 16. It also acquires the actual flow signal from flow sensor 7 and the second required flow rate. The comparison is performed, and based on the comparison results, the second target speed is adjusted using a PID proportional-integral-derivative closed-loop control method to achieve flow closed-loop control.

[0105] In this embodiment, the first hydraulic pump 2 is a fixed displacement pump. The reversible hydraulic pump motor 14 is also a fixed displacement pump when in hydraulic pump mode. Furthermore, the displacement of the reversible hydraulic pump motor 14 is greater than the displacement of the first hydraulic pump 2.

[0106] Specifically, the vehicle controller sends speed control signals to the first motor controller and the second motor controller to control the speeds of the electric motor 3 and the integrated electric generator 16, respectively. During this process, the displacement of the first hydraulic pump 2 and the reversible hydraulic pump motor 14 remains constant. The output system flow rate changes with the speed of the electric motor 3. The actual flow rate signal of the rodless chamber of the hydraulic cylinder 8 is acquired and sent to the vehicle controller. The vehicle controller calculates and adjusts the speeds of the first and second motor controllers, thereby changing the loop flow rate and achieving closed-loop control of the loop flow rate.

[0107] When performing closed-loop control of the excavator stick, a PID proportional-integral-derivative closed-loop control system is used for the retracted stick. PID control uses the proportional term (P) to quickly respond to errors, the integral term (I) to eliminate steady-state errors, and the derivative term (D) to predict error trends, thus achieving more precise control. Even when the excavator stick exhibits a certain degree of nonlinearity or parameter variations, PID control maintains good control performance. In the scenario of excavator stick retraction, PID control ensures that the excavator stick moves accurately at the predetermined speed and position, while reducing overshoot and oscillation, improving the system's response speed and control accuracy. Through appropriate parameter adjustments, the PID controller can adapt to different operating conditions and performance requirements, achieving efficient and reliable excavator stick control.

[0108] Through its own closed-loop control, the system can not only respond quickly to local changes but also ensure optimal overall system performance. This reduces system fluctuations and enhances system robustness and stability.

[0109] During the boom retraction process, the actual flow signal of the rodless chamber or key system nodes is collected in real time by the flow sensor 7, and the speed of the electric motor 3 and the integrated electric generator 16 is dynamically adjusted by PID closed-loop control, thus achieving precise flow matching. Since the first hydraulic pump 2 and the reversible hydraulic pump motor 14 are both fixed displacement pumps, their output flow is only related to the speed. Therefore, the oil flow requirements at different stages of the retraction process can be accurately met by closed-loop speed control. The PID controller continuously adjusts the speed of the electric motor 3 and the integrated electric generator 16 according to the deviation between the actual flow and the target flow, thereby avoiding overflow loss caused by excessive flow or action delay caused by insufficient flow, effectively improving the energy utilization efficiency and action response quality under the retraction condition.

[0110] Based on the above embodiments, in an optional embodiment of the present invention, steps S26 and S35 specifically include: the vehicle controller calculates the target speed of the electric motor 3 and the integrated electric generator 16 based on the flow control equation of the first hydraulic pump 2 and the total constant displacement of the first hydraulic pump 2 and the reversible hydraulic pump motor 14. When the first hydraulic pump 2 and the reversible hydraulic pump motor 14 operate simultaneously, priority is given to ensuring the output flow of the first hydraulic pump 2 to reduce energy waste.

[0111] Preferably, S2 also includes S27; S27: After the hydraulic cylinder 8 extends to its full position, close all solenoid valves.

[0112] Preferably, S3 also includes S35; S35: After the hydraulic cylinder 8 retracts to its position, all solenoid valves are closed.

[0113] In a preferred embodiment of the present invention, when the first hydraulic pump 2 and the reversible hydraulic pump motor 14 operate simultaneously, the vehicle controller prioritizes ensuring the output flow of the first hydraulic pump 2, with the reversible hydraulic pump motor 14 supplementing the flow on top of this. This strategy leverages the fact that the first hydraulic pump 2 is driven by the main motor 3 and has relatively higher energy conversion efficiency, prioritizing the use of the main pump to meet basic flow requirements, reducing the energy consumption of the integrated electric generator 16 under high loads, thereby further improving the overall energy efficiency of the system. Furthermore, when the hydraulic cylinder 8 extends or retracts into position, the system immediately closes all solenoid valves and stops the motor 3 and the integrated electric generator 16 or keeps them at idle speed, avoiding unnecessary energy waste. These control details further optimize the system's energy management logic, minimizing energy consumption in non-working states while ensuring operational efficiency.

[0114] The excavator boom energy recovery system and its control method based on the reversible hydraulic pump motor 14 of this invention, on the basis of the hydraulic drive system jointly realized by the electric motor 3 and the first hydraulic pump 2, introduces an integrated electric generator 16 and the reversible hydraulic pump motor 14 to realize hydraulic auxiliary drive and energy recovery energy-saving technology. This not only reduces overflow and throttling losses at the source through precise flow matching, solving the problems of high system energy consumption and severe heat generation, but also further improves the energy recovery capability of the excavator boom hydraulic system.

[0115] 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. An excavator boom energy recovery system based on a pump motor, characterized in that, The device includes a hydraulic cylinder, a reversible hydraulic pump motor, an electric generator connected to the reversible hydraulic pump motor, a three-position four-way solenoid valve with a first oil inlet, a first oil outlet, a second oil outlet and a first oil return port, a first hydraulic pump whose hydraulic pump inlet is connected to a hydraulic oil tank, a first check valve connecting the hydraulic pump outlet and the first oil inlet, an electric motor connected to the first hydraulic pump, a third check valve connecting the first oil return port and a second pipeline interface of the reversible hydraulic pump motor, and a first two-position two-way solenoid valve for connecting the pipeline between the third check valve and the second pipeline interface to the first oil inlet. The first pipeline interface of the reversible hydraulic pump motor is connected to the hydraulic oil tank through the fourth check valve and the third two-position two-way solenoid valve, and is connected to the first return port through the second two-position two-way solenoid valve pipeline; the first oil outlet pipeline is connected to the rodless chamber of the hydraulic cylinder, and the second oil outlet is connected to the rod chamber through a pipeline.

2. The excavator boom energy recovery system based on a pump motor according to claim 1, characterized in that, It also includes a flow sensor that connects the rodless chamber of the hydraulic cylinder and the first outlet.

3. The excavator boom energy recovery system based on a pump motor according to claim 1, characterized in that, It also includes a second check valve, a first relief valve, and a second relief valve; The second check valve is connected between the first two-position two-way solenoid valve and the first oil inlet; The first relief valve is connected between the first oil inlet and the hydraulic oil tank; The second relief valve is used to connect the pipeline between the third check valve and the second pipeline interface to the hydraulic oil tank.

4. A control method for an excavator boom energy recovery system based on a pump motor, characterized in that, For controlling the excavator boom energy recovery system based on any one of claims 1 to 3; The control methods include: S1. Obtain the working voltage signal output by the operating handle, and compare the working voltage signal with the preset mid-dead zone voltage range to obtain the current working state; wherein, the working state includes extension, retraction and stop; S2. When the working state is extended, the first required flow rate of the rodless chamber is obtained according to the required extension speed. The three-position four-way solenoid valve, the first two-position two-way solenoid valve, the second two-position two-way solenoid valve, the third two-position two-way solenoid valve, the electric motor and the electric generator are controlled according to the first required flow rate. When the first required flow rate exceeds the maximum flow rate threshold, the oil outlet of the first hydraulic pump and the reversible hydraulic pump motor are connected to the rodless chamber, and the second two-position two-way solenoid valve is disconnected so that the hydraulic cylinder forms a differential connection. S3. When the working state is retracted, the second required flow rate of the rod chamber is obtained according to the required retraction speed, and the three-position four-way solenoid valve, the first two-position two-way solenoid valve, the second two-position two-way solenoid valve, the third two-position two-way solenoid valve, the motor and the electric generator are controlled according to the second required flow rate. S4. When the working status is stopped, close all solenoid valves, and the motor and generator will stop or maintain idle speed.

5. The control method for the excavator boom energy recovery system based on a pump motor according to claim 4, characterized in that, First demand traffic A first flow threshold is set. Second flow threshold and the third flow threshold ; ; S2 specifically includes S21 to S25; S21. Calculate the target extension speed of the excavator stick based on the effective amplitude of the working voltage signal deviating from the mid-range dead zone voltage threshold; and calculate the first required flow rate of the rodless chamber of the hydraulic cylinder based on the target extension speed. ; S22, when At this time, the reversible hydraulic pump motor is in hydraulic motor state, and the electric generator is in generator state; the electric motor drives the first hydraulic pump to supply oil to the rodless chamber, and the hydraulic oil in the rod chamber drives the reversible hydraulic pump motor to drive the electric generator to generate electricity, and then flows back to the oil tank through the third two-position two-way solenoid valve. S23, when At this time, the reversible hydraulic pump motor is in hydraulic pump mode, used to deliver hydraulic oil from the rod chamber and hydraulic oil tank to the rodless chamber; S24, when At this time, the reversible hydraulic pump motor is in hydraulic pump mode, used to deliver hydraulic oil from the rod chamber and hydraulic oil tank to the rodless chamber, while the first hydraulic pump supplies oil to the rodless chamber. S25, when When the second and third two-position two-way solenoid valves are disconnected, the first two-position two-way solenoid valve is connected, so that the rod chamber of the hydraulic cylinder is unidirectionally connected to the rodless chamber; the first hydraulic pump supplies oil to the rodless chamber; the reversible hydraulic pump motor is in hydraulic pump mode, used to deliver hydraulic oil from the hydraulic oil tank to the rodless chamber.

6. The control method for the excavator boom energy recovery system based on a pump motor according to claim 5, characterized in that, S25 specifically includes: when At this time, the first oil inlet of the three-position four-way solenoid valve is connected to the first oil outlet, and the second oil outlet is connected to the first oil return port; the first two-position two-way solenoid valve is turned on, while the second two-position two-way solenoid valve and the third two-position two-way solenoid valve are turned off; the electric motor drives the first hydraulic pump to supply oil to the rodless chamber of the hydraulic cylinder, and at the same time the electric generator drives the reversible hydraulic pump motor to supply oil to the rodless chamber of the hydraulic cylinder through the first two-position two-way solenoid valve. At this time, the hydraulic oil in the rod chamber flows back to the main oil circuit through the third check valve and the first two-position two-way solenoid valve to form replenishment oil, that is, it flows to the rodless chamber of the hydraulic cylinder so that the hydraulic cylinder can reach the maximum extension speed.

7. The control method for the excavator boom energy recovery system based on a pump motor according to claim 5, characterized in that, S22 specifically includes: when When the first oil inlet of the three-position four-way solenoid valve is connected to the first oil outlet, and the second oil outlet is connected to the first oil return port; the third two-position two-way solenoid valve is turned on, while the first two-position two-way solenoid valve and the second two-position two-way solenoid valve are not turned on; the motor drives the first hydraulic pump to supply oil to the rodless chamber of the hydraulic cylinder, so that the hydraulic oil in the rod chamber flows back to the reversible hydraulic pump motor, and then flows into the oil tank through the third two-position two-way solenoid valve. At this time, the reversible hydraulic pump motor is in motor mode, driving the electric generator to be in generator mode, and the generated electrical energy is fed back to the energy storage device; S23 specifically includes: when When the first oil inlet of the three-position four-way solenoid valve is connected to the first oil outlet, and the second oil outlet is connected to the first oil return port; the first two-position two-way solenoid valve and the second two-position two-way solenoid valve are activated, while the third two-position two-way solenoid valve is not activated; the first hydraulic pump does not work; the electric generator drives the reversible hydraulic pump motor to supply oil to the rodless chamber of the hydraulic cylinder, so that the hydraulic oil in the rod chamber flows back to the oil inlet of the reversible hydraulic pump motor through the second two-position two-way solenoid valve for replenishment; S24 specifically includes: when At this time, the first oil inlet of the three-position four-way solenoid valve is connected to the first oil outlet, and the second oil outlet is connected to the first oil return port; the first two-position two-way solenoid valve and the second two-position two-way solenoid valve are activated, while the third two-position two-way solenoid valve is deactivated; the electric motor drives the first hydraulic pump to supply oil to the rodless chamber of the hydraulic cylinder, and the electric generator drives the reversible hydraulic pump motor to simultaneously supply oil to the rodless chamber of the hydraulic cylinder through the first two-position two-way solenoid valve; at this time, the hydraulic oil in the rod chamber flows back to the oil inlet of the reversible hydraulic pump motor through the second two-position two-way solenoid valve for replenishment.

8. The control method for the excavator boom energy recovery system based on a pump motor according to claim 4, characterized in that, Second demand flow A fourth flow threshold is set. and the fifth flow threshold ; S3 specifically includes: S31. Calculate the target retraction speed of the excavator stick based on the effective amplitude of the working voltage signal deviating from the mid-dead zone voltage threshold; and calculate the second required flow rate of the rod chamber of the hydraulic cylinder based on the target retraction speed. ; S32, when At this time, the reversible hydraulic pump motor is in hydraulic motor mode, and the electric generator is in generator mode; the electric motor drives the first hydraulic pump to supply oil to the rod chamber, and the hydraulic oil in the rodless chamber drives the reversible hydraulic pump motor to drive the electric generator to generate electricity, and then flows back to the oil tank through the third two-position two-way solenoid valve. S33, when At this time, the reversible hydraulic pump motor is in hydraulic pump mode, supplying oil to the rod chamber, while the hydraulic oil in the rodless chamber flows back to the hydraulic oil tank. S34, when At this time, the reversible hydraulic pump motor is in hydraulic pump mode, supplying oil to the rod chamber, while the first hydraulic pump supplies oil to the rod chamber, and the hydraulic oil in the rodless chamber flows back to the hydraulic oil tank.

9. The control method for the excavator boom energy recovery system based on a pump motor according to claim 8, characterized in that, S32 specifically includes: when When the first oil inlet of the three-position four-way solenoid valve is connected to the second oil outlet, and the first oil outlet is connected to the first return oil port; the third two-position two-way solenoid valve is activated, while the first two-position two-way solenoid valve and the second two-position two-way solenoid valve are deactivated; the electric motor drives the first hydraulic pump to supply oil to the rod chamber of the hydraulic cylinder, causing the hydraulic oil in the rodless chamber to flow back to the reversible hydraulic pump motor, and then flow into the oil tank through the third two-position two-way solenoid valve; at this time, the reversible hydraulic pump motor is in motor mode, driving the electric generator to be in generator mode, and the generated electrical energy is fed back to the energy storage device; S33 specifically includes: when When the first oil inlet of the three-position four-way solenoid valve is connected to the second oil outlet, and the first oil outlet is connected to the first oil return port; the first two-position two-way solenoid valve, the second two-position two-way solenoid valve, and the third two-position two-way solenoid valve are activated; the electric generator drives the reversible hydraulic pump motor to supply oil to the rod chamber of the hydraulic cylinder; part of the hydraulic oil in the rodless chamber is replenished to the first pipeline interface of the reversible hydraulic pump motor, and part flows back to the hydraulic oil tank; S34 specifically includes: when At this time, the first oil inlet of the three-position four-way solenoid valve is connected to the second oil outlet, and the first oil outlet is connected to the first oil return port; the first two-position two-way solenoid valve, the second two-position two-way solenoid valve, and the third two-position two-way solenoid valve are activated; the electric motor drives the first hydraulic pump to supply oil to the rod chamber of the hydraulic cylinder, and the electric generator drives the reversible hydraulic pump motor to supply oil to the rod chamber of the hydraulic cylinder through the first two-position two-way solenoid valve, so that the hydraulic oil in the rodless chamber flows back to the hydraulic oil tank.

10. The control method for the excavator boom energy recovery system based on a pump motor according to any one of claims 4 to 9, characterized in that, The first hydraulic pump is a fixed displacement pump; the reversible hydraulic pump motor is also a fixed displacement pump when it is in hydraulic pump mode. When a pump motor-based excavator boom energy recovery system is equipped with a flow sensor: Step S2 also includes S26; S26. Based on the first demand flow rate Obtain the first target speed of the electric motor and the integrated electric generator, and drive the electric motor and the integrated electric generator; obtain the actual flow signal from the flow sensor and compare it with the first required flow rate. The comparison is performed, and based on the comparison results, the first target speed is adjusted using a PID proportional-integral-derivative closed-loop control method to achieve flow closed-loop control. Step S3 also includes S35; S35, Based on the second demand flow The system acquires the operating status of the electric motor and the integrated electric generator, as well as the second target speed, and drives the electric motor and the integrated electric generator; it also acquires the actual flow signal from the flow sensor and the second required flow rate. The comparison is performed, and based on the comparison results, the second target speed is adjusted using a PID proportional-integral-derivative closed-loop control method to achieve flow closed-loop control.

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