Energy recovery system for excavator and pump motor based excavator boom and stick

Abstract

The present application provides excavator and energy recovery system of excavator movable arm and bucket based on pump motor, and relates to the technical field of excavator.The energy recovery system comprises a bucket cylinder, a first three-position four-way electromagnetic reversing valve adapted to switch the rod cavity and the rodless cavity of the bucket cylinder to be communicated with the first two-position two-way electromagnetic reversing valve and the second two-position three-way electromagnetic reversing valve respectively, a movable arm cylinder, a second three-position four-way electromagnetic reversing valve adapted to switch the rod cavity and the rodless cavity of the movable arm cylinder to be communicated with the first two-position three-way electromagnetic reversing valve and the second two-position two-way electromagnetic reversing valve respectively, a hydraulic pump adapted to supply hydraulic oil in a hydraulic oil tank to the first two-position two-way electromagnetic reversing valve and the third two-position two-way electromagnetic reversing valve, and a motor drivingly connected to the hydraulic pump.A pump motor is connected between the second two-position two-way electromagnetic reversing valve and the hydraulic oil tank, an electric motor generator integrated machine is drivingly connected to the pump motor, and an energy storage device is electrically connected to the motor and the electric motor generator integrated machine.

Description

Technical Field

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

[0002] Excavators, as core material handling and earthmoving equipment in the engineering construction field, are widely used in infrastructure, mining, and municipal engineering projects due to their multi-degree-of-freedom motion coordination, heavy load adaptability, and ability to handle complex terrain. Among these components, the boom and stick, as key actuators performing core operational actions, account for a significant portion of operational energy consumption. Improving system energy efficiency and reducing energy consumption have always been important directions for technological research and development in the industry.

[0003] Traditional excavator boom and stick drive systems mostly employ a single hydraulic drive mode, where the engine drives a hydraulic pump to provide high-pressure oil to drive the cylinders. This approach suffers from drawbacks such as low energy conversion efficiency, significant energy loss during operation, and severe heat generation in the hydraulic system. Furthermore, the substantial amount of gravitational potential energy and hydraulic energy generated during boom lowering and stick resetting is directly consumed by the relief valve, resulting in energy waste and exacerbating equipment operating costs and environmental impact.

[0004] Existing energy-saving excavator drive systems mostly focus on single energy recovery technologies or partial drive optimizations, such as using hydraulic accumulators or batteries for energy storage. However, these systems generally suffer from low energy recovery efficiency, poor adaptability of energy storage units, and insufficient system stability, making it difficult to balance load adaptability and energy-saving effects under complex boom and stick operating conditions. Furthermore, existing systems have weak coordinated control capabilities for energy recovery and reuse during combined boom and stick movements, failing to fully realize the energy-saving potential of multi-actuator collaborative operations. Summary of the Invention

[0005] The present invention provides an energy recovery system for an excavator and a pump motor-based excavator boom and stick, which aims to improve at least one of the above-mentioned technical problems.

[0006] To address the aforementioned technical problems, this invention provides an energy recovery system for the boom and stick of an excavator based on a pump motor. The system includes a stick cylinder, a first three-position four-way solenoid valve adapted to switch the rod-side and rodless-side chambers of the stick cylinder between a first two-position two-way solenoid valve and a second two-position three-way solenoid valve, a boom cylinder, a second three-position four-way solenoid valve adapted to switch the rod-side and rodless-side chambers of the boom cylinder between the first two-position three-way solenoid valve and the second two-position two-way solenoid valve, a hydraulic pump adapted to supply hydraulic oil from the hydraulic tank to the first two-position two-way solenoid valve and the third two-position two-way solenoid valve, and an electric motor driven by the hydraulic pump. A pump motor is connected via piping between the second two-position two-way solenoid valve and the hydraulic tank, an integrated electric generator is driven by the pump motor, and an energy storage device is electrically connected to the electric motor and the integrated electric generator.

[0007] The second two-position three-way solenoid directional valve is used to connect the hydraulic oil flowing out of the first three-position four-way solenoid directional valve to the second two-position two-way solenoid directional valve or the hydraulic oil tank.

[0008] The pipeline of the first two-position two-way solenoid directional valve is connected to the third two-position two-way solenoid directional valve.

[0009] The first two-position three-way solenoid directional valve is used to connect the third two-position two-way solenoid directional valve to the second three-position four-way solenoid directional valve, or to connect the second two-position two-way solenoid directional valve to the third two-position two-way solenoid directional valve.

[0010] As a preferred aspect of the present invention, the energy recovery system further includes a first throttle valve connected between a first three-position four-way solenoid directional valve and a first two-position two-way solenoid directional valve, and a second throttle valve connected between a first two-position three-way solenoid directional valve and a second three-position four-way solenoid directional valve.

[0011] As a preferred aspect of the present invention, the energy recovery system further includes a second check valve and a third check valve.

[0012] The inlet of the third check valve is used to input the hydraulic oil flowing out of the second three-position four-way solenoid directional valve.

[0013] The outlet of the third check valve, the inlet of the second check valve, and the inlet of the second overflow valve are all connected to the pump motor via a second two-position two-way solenoid directional valve.

[0014] The outlet of the second check valve is connected to the first two-position three-way solenoid directional valve.

[0015] As a preferred aspect of the present invention, the energy recovery system further includes a first check valve and a first overflow valve.

[0016] The inlets of the first check valve and the first relief valve are connected to the hydraulic pump.

[0017] The outlet of the first relief valve is connected to the hydraulic oil tank.

[0018] The oil outlet of the first check valve is connected to the first two-position two-way solenoid directional valve and the third two-position two-way solenoid directional valve.

[0019] As a preferred aspect of the present invention, the control method when only the boom cylinder is activated is as follows:

[0020] Determine whether the boom cylinder is in the extended or retracted state.

[0021] When the stick is determined to be in the extension position, the first three-position four-way solenoid directional valve is controlled to be in the position that allows hydraulic oil to enter the rodless chamber of the stick cylinder. When the stick is determined to be in the retraction position, the first three-position four-way solenoid directional valve is controlled to be in the position that allows hydraulic oil to enter the rod chamber of the stick cylinder.

[0022] The flow area of ​​the first throttle valve is adjusted according to the pilot control pressure difference, and the hydraulic pump is controlled to supply oil to the corresponding working chamber of the boom cylinder. Based on the pressure difference between the rodless chamber and the rod chamber of the boom cylinder, it is determined whether oil needs to be supplied simultaneously by the hydraulic pump and the pump motor.

[0023] When simultaneous oil supply is required, the hydraulic pump and pump motor are connected in parallel to supply oil to the corresponding working chamber of the boom cylinder. When simultaneous oil supply is not required, the hydraulic pump supplies oil to the corresponding working chamber of the boom cylinder alone, and determines whether the energy recovery conditions are met based on the state of charge of the energy storage device and / or the outlet pressure of the pump motor.

[0024] When energy recovery conditions are met, the pump motor operates as a hydraulic motor, and the integrated electric generator operates as a generator, controlling the return oil from the boom cylinder to drive the pump motor for energy recovery. Otherwise, the return oil from the boom cylinder returns to the hydraulic tank via the second two-position three-way solenoid valve.

[0025] As a preferred aspect of the present invention, the control method when only the boom cylinder is actuated is as follows:

[0026] Determine whether the boom cylinder is in the extended or retracted position.

[0027] When the boom is determined to be in the extension position, the second-third-position four-way solenoid directional valve is controlled to be in the position that allows hydraulic oil to enter the rodless chamber of the boom cylinder. When the boom is determined to be in the retraction position, the second-third-position four-way solenoid directional valve is controlled to be in the position that allows hydraulic oil to enter the rod chamber of the boom cylinder.

[0028] The flow area of ​​the second throttle valve is adjusted according to the pilot control pressure difference of the second throttle valve, and the hydraulic pump is controlled to supply oil to the corresponding working chamber of the boom cylinder.

[0029] Determine whether the energy recovery conditions are met based on the state of charge of the energy storage device and / or the outlet pressure of the pump motor.

[0030] When energy recovery conditions are met, the pump motor operates as a hydraulic motor, and the integrated electric generator operates as a generator, controlling the return oil from the boom cylinder to flow into the pump motor for energy recovery. Otherwise, the return oil from the boom cylinder returns to the hydraulic oil tank via the second relief valve.

[0031] As a preferred aspect of the present invention, the control method for when the stick cylinder and the boom cylinder operate simultaneously is as follows:

[0032] Determine the operating conditions of the boom cylinder and the stick cylinder.

[0033] When the boom cylinder is determined to be in the extended position, the first three-position four-way solenoid directional valve is controlled to be in the position that allows hydraulic oil to enter the rodless chamber of the boom cylinder. When the boom cylinder is determined to be in the retracted position, the first three-position four-way solenoid directional valve is controlled to be in the position that allows hydraulic oil to enter the rod chamber of the boom cylinder.

[0034] When the boom cylinder is determined to be in the extended position, the second-third-position four-way solenoid directional valve is controlled to be in the position that allows hydraulic oil to enter the rodless chamber of the boom cylinder. When the boom cylinder is determined to be in the retracted position, the second-third-position four-way solenoid directional valve is controlled to be in the position that allows hydraulic oil to enter the rod chamber of the boom cylinder.

[0035] The hydraulic oil output from the control hydraulic pump is split and supplied to the corresponding working chambers of the stick cylinder and boom cylinder respectively, so as to realize the synchronous movement of the stick and boom.

[0036] Determine whether the energy recovery conditions are met based on the state of charge of the energy storage device and / or the outlet pressure of the pump motor.

[0037] When energy recovery conditions are met, the return oil from the control stick cylinder and boom cylinder merges and enters the pump motor for energy recovery. Otherwise, the return oil from the control stick cylinder returns to the hydraulic oil tank through the second two-position three-way solenoid valve. The return oil from the control boom cylinder returns to the hydraulic oil tank through the second relief valve.

[0038] In a preferred aspect of the present invention, there are two boom cylinders, namely a first boom cylinder and a second boom cylinder. The rodless chamber pipelines of the first boom cylinder and the second boom cylinder are connected. The rod-side chamber pipelines of the first boom cylinder and the second boom cylinder are connected.

[0039] As a preferred aspect of the present invention, the energy storage device is configured as a supercapacitor.

[0040] In a preferred aspect of the present invention, the first three-position four-way solenoid directional valve is provided with working port A, working port B, working port C, and working port D, and is configured such that working port A can be switched to be connected to one of working ports B and C, and the other of working ports B and C is connected to working port D. Working port A is connected to the first two-position two-way solenoid directional valve. Working port B is connected to the rodless chamber of the boom cylinder. Working port C is connected to the rod chamber of the boom cylinder.

[0041] In a preferred aspect of the present invention, the second three-position four-way solenoid directional valve is provided with a working port U, a working port V, a working port W, and a working port X, and is configured such that working port U can be switched to be connected to one of working ports V and W, and the other of working ports V and W is connected to working port X. Working port V is connected to the rodless chamber of the boom cylinder. Working port W is connected to the rod chamber of the boom cylinder. Working port X is connected to the second two-position two-way solenoid directional valve and the second relief valve.

[0042] In a preferred aspect of the present invention, the first two-position three-way solenoid directional valve is provided with a working port R, a working port S, and a working port T, and is configured such that the working port R can be switched to be connected to either the working port S or the working port T. The working port R is connected to the third two-position two-way solenoid directional valve. The working port S is connected to the working port U. The working port T is connected to the second two-position two-way solenoid directional valve.

[0043] In a preferred aspect of the present invention, the second two-position three-way solenoid directional valve is provided with a working port G, a working port J, and a working port H, and is configured such that working port G can be switched to be connected to working port J or working port H. Working port G is connected to working port D. Working port J is connected to the hydraulic oil tank. Working port H is connected to the second two-position two-way solenoid directional valve.

[0044] In a preferred aspect of the present invention, the first two-position two-way solenoid directional valve is provided with a working port E and a working port F, and is configured to be able to connect or disconnect. Working port E is connected to a hydraulic pump. Working port F is connected to working port A.

[0045] In a preferred aspect of the present invention, the second two-position two-way solenoid directional valve is provided with a working port K and a working port L, and is configured to be able to connect or disconnect. The working port K is connected to the second three-position four-way solenoid directional valve, the working port T, and the second relief valve. The working port L is connected to the pump motor.

[0046] In a preferred aspect of the present invention, the third two-position two-way solenoid valve is provided with a working port P and a working port Q, and is configured to be able to connect or disconnect. The working port P is connected to the first two-position two-way solenoid valve and the hydraulic pump. The working port Q is connected to the working port R.

[0047] This application also provides an excavator that includes the energy recovery system for the excavator boom and stick based on the pump motor described in any section of the first aspect.

[0048] By adopting the above technical solution, the present invention can achieve the following technical effects:

[0049] This invention achieves efficient recovery and reuse of hydraulic energy from the boom and stick throughout the entire operating cycle by introducing an integrated pump motor and electric generator, coupled with a supercapacitor as an energy storage unit. During boom lowering and stick resetting, the system converts gravitational potential energy into electrical energy stored in the supercapacitor. Under high-load conditions such as boom lifting and stick digging, the supercapacitor releases electrical energy to drive the pump motor, outputting high-pressure hydraulic fluid that supplies oil in parallel with the main hydraulic pump. This effectively reduces the peak load and throttling losses of the main drive system, significantly improving overall machine efficiency. Simultaneously, the use of an independent electro-hydraulic drive circuit and the coordinated control of multiple directional valves enables bidirectional energy flow during independent or combined boom and stick movements. This avoids load impacts caused by the coupling of multiple actuator actions, improving system stability and responsiveness.

[0050] In addition, supercapacitors have advantages such as high-current rapid charging and discharging, long cycle life, and strong environmental adaptability. They can adapt to the complex working conditions of excavators with frequent start-stop and drastic load fluctuations, further ensuring the efficiency and reliability of energy recovery and release processes, and ultimately achieving a comprehensive improvement in energy saving, consumption reduction and operational stability of excavators. Attached Figure Description

[0051] 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.

[0052] Figure 1 This is a schematic diagram of an energy recovery system.

[0053] The markings in the diagram are: 1-Hydraulic pump, 2-Electric motor, 3-Electric generator, 4-Pump motor, 5-First relief valve, 6-Second relief valve, 7-First check valve, 8-Second check valve, 9-Third check valve, 10-First two-position two-way solenoid directional valve, 11-Second two-position two-way solenoid directional valve, 12-First two-position three-way solenoid directional valve, 13-Second two-position three-way solenoid directional valve, 14-First throttle valve, 15-Second throttle valve, 16-First three-position four-way solenoid directional valve, 17-Second three-position four-way solenoid directional valve, 18-Stick cylinder, 19-First boom cylinder, 20-Second boom cylinder, 21-Hydraulic oil tank, 22-Third two-position two-way solenoid directional valve. Detailed Implementation

[0054] 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.

[0055] Example 1, by Figure 1 As shown, this embodiment of the invention provides an energy recovery system for the boom and stick of an excavator based on a pump motor 4. It includes a stick cylinder 18, a first three-position four-way solenoid valve 16 adapted to switch the rod-side and rodless-side chambers of the stick cylinder 18 between a first two-position two-way solenoid valve 10 and a second two-position three-way solenoid valve 13, a boom cylinder, a second three-position four-way solenoid valve 17 adapted to switch the rod-side and rodless-side chambers of the boom cylinder between a first two-position three-way solenoid valve 12 and a second two-position two-way solenoid valve 11, a hydraulic pump 1 adapted to supply hydraulic oil from a hydraulic tank 21 to the first two-position two-way solenoid valve 10 and a third two-position two-way solenoid valve 22, and a motor 2 driven by the hydraulic pump 1. The pump motor 4 is connected in pipeline between the second two-position two-way solenoid valve 11 and the hydraulic tank 21, an integrated electric generator 3 is driven by the pump motor 4, and an energy storage device is electrically connected to the motor 2 and the integrated electric generator 3. The system includes two boom cylinders: a first boom cylinder 19 and a second boom cylinder 20. The rodless chambers of both cylinders are connected, as are the rod-side chambers. The energy storage device is either a supercapacitor or a battery.

[0056] The second two-position three-way solenoid directional valve 13 is used to connect the hydraulic oil flowing out of the first three-position four-way solenoid directional valve 16 to the second two-position two-way solenoid directional valve 11 or the hydraulic oil tank 21.

[0057] The first two-position two-way solenoid directional valve 10 is connected to the third two-position two-way solenoid directional valve 22. The first two-position three-way solenoid directional valve 12 is used to connect the third two-position two-way solenoid directional valve 22 to the second three-position four-way solenoid directional valve 17, or to connect the second two-position two-way solenoid directional valve 11 to the third two-position two-way solenoid directional valve 22.

[0058] This invention achieves efficient recovery and reuse of hydraulic energy from the boom and stick throughout the entire operating cycle by introducing a pump motor 4 and an integrated electric generator 3, along with a supercapacitor as an energy storage unit. During boom lowering and stick resetting, the system converts gravitational potential energy into electrical energy stored in the supercapacitor. Under high-load conditions such as boom lifting and stick digging, the supercapacitor releases electrical energy to drive the pump motor 4, which outputs high-pressure hydraulic fluid, supplying oil in parallel with the main hydraulic pump 1. This effectively reduces the peak load and throttling losses of the main drive system, significantly improving overall machine efficiency. Simultaneously, the use of an independent electro-hydraulic drive circuit and the coordinated control of multiple directional valves enables bidirectional energy flow during independent or combined boom and stick movements, avoiding load impacts caused by the coupling of multiple actuator actions and improving system stability and response performance.

[0059] In addition, supercapacitors have advantages such as high-current rapid charging and discharging, long cycle life, and strong environmental adaptability. They can adapt to the complex working conditions of excavators with frequent start-stop and drastic load fluctuations, further ensuring the efficiency and reliability of energy recovery and release processes, and ultimately achieving a comprehensive improvement in energy saving, consumption reduction and operational stability of excavators.

[0060] Preferably, the energy recovery system further includes a first throttle valve 14 connected between a first three-position four-way solenoid valve 16 and a first two-position two-way solenoid valve 10, and a second throttle valve 15 connected between a first two-position three-way solenoid valve 12 and a second three-position four-way solenoid valve 17.

[0061] Preferably, the energy recovery system further includes a second check valve 8 and a third check valve 9. The inlet of the third check valve 9 is used to input hydraulic oil flowing from the second three-position four-way solenoid directional valve 17. The outlet of the third check valve 9, the inlet of the second check valve 8, and the inlet of the second relief valve 6 are all connected to the pump motor 4 through the second two-position two-way solenoid directional valve 11. The outlet of the second check valve 8 is connected to the first two-position three-way solenoid directional valve 12.

[0062] Preferably, the energy recovery system further includes a first check valve 7 and a first relief valve 5. The inlets of the first check valve 7 and the first relief valve 5 are connected to the hydraulic pump 1. The outlet of the first relief valve 5 is connected to the hydraulic oil tank 21. The outlet of the first check valve 7 is connected to a first two-position two-way solenoid directional valve 10 and a third two-position two-way solenoid directional valve 22.

[0063] Based on the above embodiments, in an optional embodiment of the present invention, the first three-position four-way solenoid directional valve 16 is provided with working port A, working port B, working port C, and working port D, and is configured such that working port A can be switched to be connected to one of working port B and working port C, and the other of working port B and working port C is connected to working port D. Working port A is connected to the first two-position two-way solenoid directional valve 10. Working port B is connected to the rodless chamber of the boom cylinder 18. Working port C is connected to the rod chamber of the boom cylinder 18.

[0064] The second three-position four-way solenoid directional valve 17 is provided with working port U, working port V, working port W, and working port X, and is configured such that working port U can switch between being connected to one of working ports V and W, and the other of working ports V and W is connected to working port X. Working port V is connected to the rodless chamber of the boom cylinder. Working port W is connected to the rod chamber of the boom cylinder. Working port X is connected to the second two-position two-way solenoid directional valve 11 and the second relief valve 6.

[0065] The first two-position three-way solenoid directional valve 12 is provided with a working port R, a working port S, and a working port T, and is configured such that the working port R can be switched to be connected to either the working port S or the working port T. The working port R is connected to the third two-position two-way solenoid directional valve 22. The working port S is connected to the working port U. The working port T is connected to the second two-position two-way solenoid directional valve 11.

[0066] The second two-position three-way solenoid directional valve 13 is provided with working port G, working port J, and working port H, and is configured such that working port G can be switched to be connected to working port J or working port H. Working port G is connected to working port D. Working port J is connected to the hydraulic oil tank 21. Working port H is connected to the second two-position two-way solenoid directional valve 11.

[0067] The first two-position two-way solenoid directional valve 10 is provided with a working port E and a working port F, and is configured to be able to connect or disconnect. Working port E is connected to the hydraulic pump 1. Working port F is connected to working port A.

[0068] The second two-position two-way solenoid directional valve 11 is provided with a working port K and a working port L, and is configured to be able to connect or disconnect. The working port K is connected to the second three-position four-way solenoid directional valve 17, the working port T, and the second relief valve 6. The working port L is connected to the pump motor 4.

[0069] The third two-position two-way solenoid valve has a working port P and a working port Q, and is configured to be able to connect or disconnect. Working port P is connected to the first two-position two-way solenoid valve 10 and the hydraulic pump 1. Working port Q is connected to working port R.

[0070] The following is a classification of the pipelines based on the hydraulic oil flow path under different operating conditions of the energy recovery system: boom lifting and lowering circuit, boom energy recovery circuit, boom lifting and lowering circuit, boom energy recovery circuit, boom-boom combined drive circuit, boom-boom combined energy recovery circuit, and auxiliary oil replenishment circuit.

[0071] like Figure 1 As shown, the boom lifting and lowering circuit includes a hydraulic oil tank 21. The hydraulic oil tank 21 is connected to the inlet of the hydraulic pump 1. The shaft of the hydraulic pump 1 is driven and connected to the motor 2. The outlet of the hydraulic pump 1 is connected to the inlet of the first check valve 7. The outlet of the first check valve 7 is connected to the working port E of the first two-position two-way solenoid directional valve 10. The working port A of the first three-position four-way solenoid directional valve 16 is connected to the working port F of the first two-position two-way solenoid directional valve 10 through the first throttle valve 14. The working port B of the first three-position four-way solenoid directional valve 16 is connected to the rodless chamber of the boom cylinder 18. The boom cylinder 18 is used to drive the boom to rise and fall.

[0072] Based on the above embodiments, in an optional embodiment of the present invention, such as Figure 1 As shown, there is one boom cylinder 18. The rod-side and rodless sides of the boom cylinder 18 are respectively connected to an energy recovery circuit with flow control, enabling efficient closed-loop energy management throughout the entire boom digging and resetting cycle. This significantly improves energy utilization during boom operation, while the independent drive circuit avoids cylinder tilting and wear caused by uneven load distribution, greatly extending the service life and operational stability of the boom mechanism.

[0073] like Figure 1 As shown, the boom lifting and lowering circuit also includes a first relief valve 5 and a first throttle valve 14. The first throttle valve 14 is connected between the working port A of the first three-position four-way solenoid directional valve 16 and the working port F of the first two-position two-way solenoid directional valve 10. The inlet of the first relief valve 5 is connected to the outlet of the hydraulic pump 1. The outlet of the first relief valve 5 is connected to the hydraulic oil tank 21.

[0074] Specifically, the first overflow valve 5 effectively prevents excessive pressure in the boom lifting and lowering circuits. The first throttle valve 14 effectively controls the lifting and lowering speed of the boom cylinder 18, bringing it as close to the ideal state as possible, which has significant practical implications.

[0075] like Figure 1As shown, the boom energy recovery circuit includes a second two-position three-way solenoid directional valve 13, a second two-position two-way solenoid directional valve 11, and an energy recovery device. The energy recovery device includes a pump motor 4 and an integrated electric generator 3. The working port D of the first three-position four-way solenoid directional valve 16 is connected to the working port G of the second two-position three-way solenoid directional valve 13. The working port H of the second two-position three-way solenoid directional valve 13 is connected to the working port K of the second two-position two-way solenoid directional valve 11. The working port L of the second two-position two-way solenoid directional valve 11 is connected to the working port N of the pump motor 4. The pump motor 4 is driven and connected to the integrated electric generator 3. At this time, the pump motor 4 is in motor mode, and the integrated electric generator 3 is in generator mode. The pump motor 4 drives the integrated electric generator 3 to rotate and generate electricity. The working port M of the pump motor 4 is connected to the hydraulic oil tank 21. Specifically, the energy recovery component can convert the hydraulic energy of the boom movement or the gravitational potential energy during lowering into electrical energy in the supercapacitor, greatly reducing energy loss.

[0076] like Figure 1 As shown, the energy recovery device also includes a second relief valve 6. The inlet pipe of the second relief valve 6 is connected to the working port N of the pump motor 4. The outlet of the second relief valve 6 is connected to the hydraulic oil tank 21. Specifically, the second relief valve 6 can prevent excessive pressure within the energy recovery device.

[0077] like Figure 1 As shown, the boom lifting and lowering circuit includes a hydraulic oil tank 21. The hydraulic oil tank 21 is connected to the inlet of the hydraulic pump 1. The shaft of the hydraulic pump 1 is driven and connected to the motor 2. The outlet of the hydraulic pump 1 is connected to the inlet of the first check valve 7. The outlet of the first check valve 7 is connected to the working port P of the third two-position two-way solenoid directional valve 22. The working port Q of the third two-position two-way solenoid directional valve 22 is connected to the working port R of the first two-position three-way solenoid directional valve 12. The working port S of the first two-position three-way solenoid directional valve 12 is connected to the working port U of the second three-position four-way solenoid directional valve 17 through the second throttle valve 15. The working port V of the second three-position four-way solenoid directional valve 17 is connected to the rodless chamber of the first boom cylinder 19 and the second boom cylinder 20. The first boom cylinder 19 and the second boom cylinder 20 are used to drive the boom to rise and fall.

[0078] like Figure 1 As shown, there are two boom cylinders, namely a first boom cylinder 19 and a second boom cylinder 20. The first boom cylinder 19 and the second boom cylinder 20 are arranged in parallel. The rod chamber of the first boom cylinder 19 is connected to the rod chamber of the second boom cylinder 20, and the rodless chamber of the first boom cylinder 19 is connected to the rodless chamber of the second boom cylinder 20.

[0079] The second throttle valve 15 effectively controls the lifting and lowering speed of the boom cylinder, bringing it as close to the ideal state as possible, which has significant practical implications. The use of two boom cylinders avoids cylinder tilting and wear caused by uneven load distribution, greatly improving the service life and operational stability of the boom mechanism.

[0080] like Figure 1 As shown, the boom lifting and lowering circuit also includes a second relief valve 6. The inlet of the second relief valve 6 is connected to the working port K of the second two-position two-way solenoid directional valve 11. The outlet of the second relief valve 6 is connected to the hydraulic oil tank 21.

[0081] like Figure 1 As shown, the boom energy recovery circuit includes a third check valve 9, a second two-position two-way solenoid directional valve 11, and an energy recovery device. The energy recovery device includes a pump motor 4 and an integrated electric generator 3. The working port K of the second three-position four-way solenoid directional valve 17 is connected to the inlet port of the third check valve 9. The outlet port of the third check valve 9 is connected to the working port K of the second two-position two-way solenoid directional valve 11. The working port L of the second two-position two-way solenoid directional valve 11 is connected to the working port N of the pump motor 4. The working port M of the pump motor 4 is connected to the hydraulic oil tank 21. The shaft of the pump motor 4 is connected to the integrated electric generator 3, at which time the motor 2 rotates in reverse, acting as a generator.

[0082] like Figure 1 As shown, the boom-stick combined drive circuit includes a hydraulic oil tank 21. The hydraulic oil tank 21 is connected to the inlet of the hydraulic pump 1. The shaft of the hydraulic pump 1 is driven by the electric motor 2. The outlet of the hydraulic pump 1 is connected to the inlet of the first check valve 7. The outlet of the first check valve 7 is connected to the working port R of the first two-position three-way solenoid directional valve 12 and the working port E of the first two-position two-way solenoid directional valve 10, respectively. The hydraulic oil drives the cylinders to move along the two paths respectively.

[0083] The first path is as follows: the outlet of the first one-way valve 7 is connected to the working port P of the third two-position two-way solenoid directional valve 22. The working port Q of the third two-position two-way solenoid directional valve 22 is connected to the working port R of the first two-position three-way solenoid directional valve 12. The working port S of the first two-position three-way solenoid directional valve 12 is connected to the working port U of the second three-position four-way solenoid directional valve 17 through the second throttle valve 15. The working port V of the second three-position four-way solenoid directional valve 17 is connected to the rodless chamber of the first boom cylinder 19 and the second boom cylinder 20.

[0084] The second route is as follows: the outlet of the first one-way valve 7 is connected to the working port E of the first two-position two-way solenoid directional valve 10. The working port F of the first two-position two-way solenoid directional valve 10 is connected to the working port A of the first three-position four-way solenoid directional valve 16 through the first throttle valve 14. The working port B of the first three-position four-way solenoid directional valve 16 is connected to the rodless chamber of the boom cylinder 18 to achieve synchronous drive of the boom and the stick.

[0085] like Figure 1 As shown, the boom-stick composite drive circuit is an organic combination of the boom lifting and lowering circuit and the arm lifting and lowering circuit. Through the orderly change of the working position of the first three-position four-way solenoid valve 16 and the second three-position four-way solenoid valve 17, the coordinated operation of the boom and stick can be realized simultaneously, avoiding the load impact and cylinder wear caused by the coupling of multiple actuators, and significantly enhancing the excavator's operational stability and equipment reliability under complex working conditions.

[0086] like Figure 1 As shown, the boom-arm composite energy recovery circuit includes a third one-way valve 9, a second two-position two-way solenoid directional valve 11, a second two-position three-way solenoid directional valve 13, and an energy recovery device. The energy recovery device includes a pump motor 4 and an integrated electric generator 3. The working port X of the second three-position four-way solenoid directional valve 17 is connected to the inlet of the third one-way valve 9. The working port H of the second two-position three-way solenoid directional valve 13 is connected to the outlet of the third one-way valve 9. The working port D of the first three-position four-way solenoid directional valve 16 is connected to the working port G of the second two-position three-way solenoid directional valve 13. The outlet of the third one-way valve 9 is connected to the working port K of the second two-position two-way solenoid directional valve 11, configured to connect to the working port N of the pump motor 4. The working port M of the pump motor 4 is connected to the hydraulic oil tank 21. The shaft of the pump motor 4 is connected to the integrated electric generator 3. At this time, the electric motor 2 rotates in reverse, acting as a generator.

[0087] like Figure 1 As shown, the boom-stick composite energy recovery circuit is a combination of the boom energy recovery circuit and the stick energy recovery circuit. It can combine and integrate the hydraulic energy generated when the boom and stick are in single or dual working conditions. After being adapted and adjusted by the power matching module, the pump motor 4 unit drives the hydraulic energy to be converted into electrical energy and efficiently charged the supercapacitor, which is different from the single mechanism independent recovery mode.

[0088] like Figure 1As shown, the auxiliary oil replenishment circuit includes a second two-position two-way solenoid directional valve 11, a second check valve 8, a first two-position three-way solenoid directional valve 12, and a third two-position two-way solenoid directional valve 22. The second two-position two-way solenoid directional valve 11, the second check valve 8, the first two-position three-way solenoid directional valve 12, and the third two-position two-way solenoid directional valve 22 are connected in series between the outlet of the first check valve 7 and the working port E of the first two-position two-way solenoid directional valve 10.

[0089] In this embodiment, the working port K of the second two-position two-way solenoid directional valve 11 is connected to the inlet of the second one-way valve 8 and the outlet of the third one-way valve 9. The working port K of the second two-position two-way solenoid directional valve 11 is also connected to the inlet of the second relief valve 6.

[0090] The present invention discloses an energy recovery system for excavator boom and stick based on pump motor 4. On the basis of the hydraulic drive system jointly realized by electric motor 2 and hydraulic pump 1, the pump motor 4 and electric generator 3 are introduced to realize the energy-saving technology of hydraulic oil replenishment and energy recovery. In addition, a supercapacitor energy storage unit is introduced to realize the efficient storage and bidirectional flow of electrical energy, which further improves the energy recovery and reuse capability during the operation of excavator boom and stick, while ensuring the stable operation and response performance of the system under complex working conditions.

[0091] In this embodiment, the solenoid valve is defined as open when energized and closed when de-energized. (See attached image) Figure 1 The operating position of the solenoid valve is always the default state (i.e., the power-off state).

[0092] Based on the above embodiments, in an optional embodiment of the present invention, the control method when only the boom cylinder 18 is activated is as follows:

[0093] Determine whether the boom cylinder 18 is in the extended or retracted state.

[0094] When the stick is determined to be in the extension condition, the first three-position four-way solenoid directional valve 16 is controlled to be in the working position that allows hydraulic oil to enter the rodless chamber of the stick cylinder 18. When the stick is determined to be in the retraction condition, the first three-position four-way solenoid directional valve 16 is controlled to be in the working position that allows hydraulic oil to enter the rod chamber of the stick cylinder 18.

[0095] The flow area of ​​the first throttle valve 14 is adjusted according to the pilot control pressure difference, and the hydraulic pump 1 is controlled to supply oil to the corresponding working chamber of the boom cylinder 18. Based on the pressure difference between the rodless chamber and the rod chamber of the boom cylinder 18, it is determined whether oil needs to be supplied simultaneously by the hydraulic pump 1 and the pump motor 4.

[0096] When simultaneous oil supply is required, hydraulic pump 1 and pump motor 4 are connected in parallel to supply oil to the corresponding working chamber of boom cylinder 18. When simultaneous oil supply is not required, hydraulic pump 1 supplies oil to the corresponding working chamber of boom cylinder 18 alone, and determines whether the energy recovery conditions are met based on the state of charge of the energy storage device and / or the outlet pressure of pump motor 4.

[0097] When the energy recovery conditions are met, pump motor 4 is in hydraulic motor mode, and electric generator 3 is in generator mode, controlling the return oil of boom cylinder 18 to drive pump motor 4 to perform energy recovery. Otherwise, the return oil from boom cylinder 18 returns to hydraulic oil tank 21 through the second two-position three-way solenoid directional valve 13.

[0098] Specifically, the control method when only the boom cylinder 18 is in motion includes the steps for boom lifting, boom lowering, and energy recovery by the system.

[0099] The process of raising the boom includes steps A1 to A4.

[0100] A1. Determine whether the pilot control pressure difference Δp1 of the first throttle valve 14 exceeds the first preset value of the first throttle valve 14. Δp1 = p5 - p6, where p5 is the pressure at the inlet of the first throttle valve 14, and p6 is the pressure at the outlet of the first throttle valve 14.

[0101] A2. When it is determined that the pilot control pressure difference Δp1 of the first throttle valve 14 exceeds the first preset value, the flow area of ​​the first throttle valve 14 is adjusted by using valve port pressure difference active control technology, and it is further determined whether the difference between the rodless chamber pressure and the rod chamber pressure of the boom cylinder 18 exceeds the second preset value of the boom.

[0102] A3. When the pressure difference between the rodless chamber and the rod chamber of the stick cylinder 18 does not exceed the second preset value of the stick, the first three-position four-way solenoid directional valve 16 is opened to the right position, and the first two-position two-way solenoid directional valve 10 is opened. Hydraulic oil enters the rodless chamber of the stick cylinder 18 through the hydraulic pump 1, the first check valve 7, the first two-position two-way solenoid directional valve 10, the first throttle valve 14, and the first three-position four-way solenoid directional valve 16 to realize the extension movement of the excavator stick.

[0103] A4. When the difference between the pressure in the rodless chamber and the pressure in the rod chamber of the boom cylinder 18 exceeds the second preset value of the boom, the first two-position two-way solenoid directional valve 10 is opened, the second two-position three-way solenoid directional valve 13, the first two-position three-way solenoid directional valve 12 and the third two-position two-way solenoid directional valve 22 are opened, and the first three-position four-way solenoid directional valve 16 is opened to the right position.

[0104] Hydraulic pump 1 and pump motor 4 are connected in parallel to supply oil. The hydraulic oil enters the rodless chamber of the stick cylinder 18 through two separate oil lines: via hydraulic pump 1, first check valve 7, first two-position two-way solenoid directional valve 10, first throttle valve 14, and first three-position four-way solenoid directional valve 16; and via pump motor 4, second two-position two-way solenoid directional valve 11, second check valve 8, first two-position three-way solenoid directional valve 12, third two-position two-way solenoid directional valve 22, first two-position two-way solenoid directional valve 10, first throttle valve 14, and first three-position four-way solenoid directional valve 16, to achieve the extension movement of the excavator stick under heavy load conditions.

[0105] Preferably, step A2 specifically includes A21 to A23.

[0106] A21. When it is determined that the pilot control pressure difference Δp1 of the first throttle valve 14 exceeds the first preset value, it is further determined whether the difference between the rodless chamber pressure and the rod chamber pressure of the boom cylinder 18 exceeds the second preset value.

[0107] A22. When it is determined that the difference between the pressure in the rodless chamber and the pressure in the rod chamber of the boom cylinder 18 exceeds the second preset value, it is expected that the electric motor 2 and the integrated electric generator 3 will be used for synchronous drive.

[0108] The control signal of the boom cylinder 18 is acquired to obtain the ideal extension speed of the boom cylinder 18 and the theoretical required flow rate. Model adaptation is used to compensate for the theoretical required flow rate to obtain the actual required flow rate of the boom cylinder 18. The pressure difference of the first throttle valve 14 is calculated to obtain the valve core opening, which is then input to the closed-loop controller. PID control is used to obtain the target speed values ​​of the electric motor 2 and the integrated electric generator 3. Threshold limits are applied based on the upper and lower allowable speed values ​​of the motor and pump, and input to the controller for speed control of the electric motor 2 and the integrated electric generator 3. The displacement of the hydraulic pump 1 and the pump motor 4 is then adjusted according to the motor speed to ensure that both the motor and pump operate within their high-efficiency range. Otherwise, step A23 is executed.

[0109] A23. Using electric motor 2 for drive: obtain the control signal of boom cylinder 18, obtain the ideal extension speed of boom cylinder 18, and obtain the theoretical required flow rate.

[0110] Model adaptation is used to compensate for the theoretical required flow rate, obtain the actual required flow rate of the boom cylinder 18, calculate the pressure difference of the first throttle valve 14, obtain the valve core opening, and input it to the closed-loop controller. PID control is used to obtain the target speed value of the motor 2. Threshold limits are set according to the upper and lower limits of the allowable speed of the motor and pump, and input to the controller to control the speed of the motor 2. Then, the displacement of the hydraulic pump 1 is adjusted according to the motor speed so that both the motor and the pump are in the high-efficiency range.

[0111] The process of lowering the pole includes steps B1 to B4.

[0112] B1. Determine whether the pilot control pressure difference Δp1 of the first throttle valve 14 exceeds the third preset value of the first throttle valve 14.

[0113] B2. When it is determined that the pilot control pressure difference Δp1 of the first throttle valve 14 exceeds the third preset value, the valve port pressure difference active control technology is used to adjust the flow area of ​​the first throttle valve 14, and further determine whether the difference between the rodless chamber pressure and the rod chamber pressure of the boom cylinder 18 exceeds the fourth preset value of the boom cylinder 18.

[0114] B3. When the difference between the pressure in the rodless chamber and the pressure in the rod chamber of the stick cylinder 18 does not exceed the fourth preset value of the stick cylinder 18, the first three-position four-way solenoid directional valve 16 is opened to the left position, and the first two-position two-way solenoid directional valve 10 is opened. The hydraulic oil enters the rod chamber of the stick cylinder 18 through the hydraulic pump 1, the first check valve 7, the first two-position two-way solenoid directional valve 10, the first throttle valve 14, and the first three-position four-way solenoid directional valve 16 to realize the retraction movement of the excavator stick.

[0115] B4. When the pressure difference between the rodless chamber and the rod chamber of the boom cylinder 18 exceeds the fourth preset value, the first two-position two-way solenoid directional valve 10, the first two-position three-way solenoid directional valve 12, the second two-position three-way solenoid directional valve 13, and the third two-position two-way solenoid directional valve 22 are opened, and the first three-position four-way solenoid directional valve 16 is opened to the left position. The hydraulic pump 1 and the pump motor 4 are connected in parallel to supply oil, and the hydraulic oil enters the rod chamber of the boom cylinder 18 through two oil circuits. The first oil circuit: enters the rodless chamber of the boom cylinder 18 through the hydraulic pump 1, the first check valve 7, the first two-position two-way solenoid directional valve 10, the first throttle valve 14, and the first three-position four-way solenoid directional valve 16. The second oil circuit: enters the rod chamber of the boom cylinder 18 through the pump motor 4, the second two-position two-way solenoid directional valve 11, the second check valve 8, the first two-position three-way solenoid directional valve 12, the third two-position two-way solenoid directional valve 22, the first two-position two-way solenoid directional valve 10, the first throttle valve 14, and the first three-position four-way solenoid directional valve 16, so as to realize the retraction movement of the excavator boom under heavy load conditions.

[0116] Preferably, step B2 specifically includes B21 to B23.

[0117] B21. When it is determined that the pilot control pressure difference Δp1 of the first throttle valve 14 exceeds the third preset value, it is further determined whether the difference between the rodless chamber pressure and the rod chamber pressure of the boom cylinder 18 exceeds the fourth preset value.

[0118] B22. When it is determined that the difference between the pressure in the rodless chamber and the pressure in the rod chamber of the boom cylinder 18 exceeds the fourth preset value, the electric motor 2 and the integrated electric generator 3 are used for synchronous drive.

[0119] The control signal of the boom cylinder 18 is acquired to obtain the ideal retraction speed of the boom cylinder 18 and the theoretical required flow rate. Then, model adaptation is used to compensate for the theoretical required flow rate to obtain the actual required flow rate of the boom cylinder 18.

[0120] The pressure difference of the first throttle valve 14 is calculated based on the actual required flow rate, and the valve core opening is obtained. This is then input to the closed-loop controller, and PID control is used to obtain the target speed values ​​of the motor 2 and the integrated electric generator 3.

[0121] Threshold limits are set based on the upper and lower permissible speeds of the motor-pump, and the input is sent to the controller to control the speeds of motor 2 and the integrated electric generator 3. The displacement of hydraulic pump 1 and pump motor 4 is then adjusted according to the motor speed to ensure that both the motor and pump operate within their high-efficiency range. Otherwise, step B23 is executed.

[0122] B23. Driven by electric motor 2. The control signal of the boom cylinder 18 is acquired to obtain the ideal retraction speed of the boom cylinder 18 and the theoretical required flow rate. Model adaptation is then used to compensate for the theoretical required flow rate to obtain the actual required flow rate of the boom cylinder 18.

[0123] The pressure difference of the first throttle valve 14 is calculated based on the actual required flow rate, and the valve core opening is obtained. This is then input to the closed-loop controller, and PID control is used to obtain the target speed value of the motor 2.

[0124] Threshold limits are set based on the upper and lower limits of the allowable speed of the motor pump, and the input is sent to the controller to control the speed of motor 2. Then, the displacement of hydraulic pump 1 is adjusted according to the motor speed so that both the motor and the pump are in the high-efficiency range.

[0125] When the boom cylinder 18 performs energy recovery, it includes steps C1 and C2.

[0126] C1. Determine if the SOC of the supercapacitor is less than the upper limit Scmax. Determine if the pressure at the working port N of pump motor 4 exceeds the fifth preset value.

[0127] C2. When it is determined that the SOC of the supercapacitor exceeds the upper limit Scmax, or the pressure at the working port N of the pump motor 4 exceeds the fifth preset value, the working ports C and D of the first three-position four-way solenoid directional valve 16 are connected, and the second two-position three-way solenoid directional valve 13 is opened, while the second two-position two-way solenoid directional valve 11 is closed, so that the hydraulic oil in the rod chamber of the boom cylinder 18 returns directly to the hydraulic oil tank 21 through the first three-position four-way solenoid directional valve 16 and the second two-position three-way solenoid directional valve 13. Otherwise, the second two-position three-way solenoid directional valve 13 is closed, the second two-position two-way solenoid directional valve 11 is opened, and the working ports C and D of the first three-position four-way solenoid directional valve 16 are connected, so that the hydraulic oil in the rod chamber of the boom cylinder 18 enters the pump motor 4 through the first three-position four-way solenoid directional valve 16, the second two-position three-way solenoid directional valve 13, and the second two-position two-way solenoid directional valve 11, thereby realizing hydraulic energy recovery.

[0128] Based on the above embodiments, in an optional embodiment of the present invention, the control method when only the boom cylinder is actuated is as follows:

[0129] Determine whether the boom cylinder is in the extended or retracted position.

[0130] When the boom is determined to be in the extension position, the second three-position four-way solenoid directional valve 17 is controlled to be in the position that allows hydraulic oil to enter the rodless chamber of the boom cylinder. When the boom is determined to be in the retraction position, the second three-position four-way solenoid directional valve 17 is controlled to be in the position that allows hydraulic oil to enter the rod chamber of the boom cylinder.

[0131] The flow area of ​​the second throttle valve 15 is adjusted according to the pilot control pressure difference of the second throttle valve 15, and the hydraulic pump 1 is controlled to supply oil to the corresponding working chamber of the boom cylinder.

[0132] Determine whether the energy recovery conditions are met based on the state of charge of the energy storage device and / or the outlet pressure of the pump motor 4.

[0133] When the energy recovery conditions are met, pump motor 4 is in hydraulic motor mode, and electric generator 3 is in generator mode, controlling the return oil from the boom cylinder to enter pump motor 4 for energy recovery. Otherwise, the return oil from the boom cylinder returns to the hydraulic oil tank 21 via the second relief valve 6.

[0134] Specifically, the control method for boom cylinder operation includes the steps of boom lifting, boom lowering, and energy recovery.

[0135] The boom lifting process includes steps D1 to D3.

[0136] D1. Determine whether the pilot control pressure difference Δp2 of the second throttle valve 15 exceeds the sixth preset value of the second throttle valve 15.

[0137] Δp2 = p7 - p8, where p7 is the pressure at the inlet of the second throttle valve 15, and p8 is the pressure at the outlet of the second throttle valve 15.

[0138] D2. When it is determined that the pilot control pressure difference Δp2 of the second throttle valve 15 exceeds the sixth preset value, the flow area of ​​the second throttle valve 15 is adjusted by using valve port pressure difference active control technology; otherwise, step D3 is executed.

[0139] D3. Open the second three-position four-way solenoid directional valve 17 to the right position, open the third two-position two-way solenoid directional valve 22, and close the first two-position three-way solenoid directional valve 12. The hydraulic oil enters the rodless chamber of the first boom cylinder 19 and the second boom cylinder 20 through the hydraulic pump 1, the first check valve 7, the third two-position two-way solenoid directional valve 22, the first two-position three-way solenoid directional valve 12, the second throttle valve 15, and the second three-position four-way solenoid directional valve 17 to realize the extension movement of the excavator boom.

[0140] Preferably, step D2 specifically includes steps D21 and D22.

[0141] D21. When it is determined that the pilot control pressure difference Δp2 of the second throttle valve 15 exceeds the sixth preset value.

[0142] D22. Using electric motor 2 as the drive, control signals for the first boom cylinder 19 and the second boom cylinder 20 are acquired to obtain the ideal extension speed of the boom cylinders and calculate the theoretical required flow rate. Model adaptation is then used to compensate for the theoretical required flow rate, obtaining the actual required flow rate of the boom cylinders. The differential pressure of the second throttle valve 15 is calculated, and the valve core opening is obtained. This information is input to the closed-loop controller, where PID control is used to obtain the target speed value of electric motor 2. Threshold limits are applied based on the upper and lower allowable speeds of the motor and pump, and this information is input to the controller for motor 2 speed control. The displacement of hydraulic pump 1 is then adjusted according to the motor speed to ensure that both the motor and pump operate within their high-efficiency range.

[0143] The lowering of the boom includes steps E1 to E3.

[0144] E1. Determine whether the pilot control pressure difference Δp2 of the second throttle valve 15 exceeds the seventh preset value of the second throttle valve 15.

[0145] E2. When it is determined that the pilot control pressure difference Δp2 of the second throttle valve 15 exceeds the seventh preset value, the flow area of ​​the second throttle valve 15 is adjusted by using valve port pressure difference active control technology; otherwise, step A3 is executed.

[0146] E3. Open the second three-position four-way solenoid directional valve 17, with the working position being the left position. Open the third two-position two-way solenoid directional valve 22, and close the first two-position three-way solenoid directional valve 12. Hydraulic oil enters the rod chamber of the first boom cylinder 19 and the second boom cylinder 20 through the hydraulic pump 1, the first check valve 7, the third two-position two-way solenoid directional valve 22, the first two-position three-way solenoid directional valve 12, the second throttle valve 15, and the second three-position four-way solenoid directional valve 17 to realize the retraction movement of the excavator boom.

[0147] Preferably, step E2 specifically includes steps E1 and E2.

[0148] E21. When it is determined that the pilot control pressure difference Δp2 of the second throttle valve 15 exceeds the seventh preset value.

[0149] E22. Driven by electric motor 2, control signals are acquired from the first boom cylinder 19 and the second boom cylinder 20 to obtain the ideal extension speed of the boom cylinders and calculate the theoretical required flow rate. Model adaptation is used to compensate for the theoretical required flow rate, obtaining the actual required flow rate of the boom cylinders. Based on the actual required flow rate, the pressure difference of the second throttle valve 15 is calculated, and the valve core opening is obtained. This is input to the closed-loop controller, using PID control to obtain the target speed value of electric motor 2. Threshold limits are applied based on the upper and lower allowable speeds of the motor and pump, and input to the controller for motor 2 speed control. The displacement of hydraulic pump 1 is then adjusted according to the motor speed to ensure that both the motor and pump operate within their high-efficiency range. The motor and pump are a combination of electric motor 2 and hydraulic pump 1.

[0150] When the boom cylinder performs energy recovery, it includes steps F1 and F2.

[0151] F1. Determine if the SOC of the supercapacitor is less than the upper limit Scmax. Determine if the outlet pressure of pump motor 4 exceeds the eighth preset value.

[0152] F2. When it is determined that the SOC of the supercapacitor exceeds the upper limit Scmax, or the outlet pressure of the pump motor 4 exceeds the eighth preset value, the working port W and working port X of the second three-position four-way solenoid directional valve 17 are connected, and the second two-position two-way solenoid directional valve 11 is closed, so that the hydraulic oil in the rod chamber of the first boom cylinder 19 and the second boom cylinder 20 returns to the hydraulic oil tank 21 through the second three-position four-way solenoid directional valve 17 and the second relief valve 6.

[0153] Otherwise, open the second two-position two-way solenoid directional valve 11 and connect the working port W and working port X of the second three-position four-way solenoid directional valve 17, so that the hydraulic oil in the rod chamber of the first boom cylinder 19 and the second boom cylinder 20 enters the pump motor 4 through the second three-position four-way solenoid directional valve 17, the third check valve 9 and the second two-position two-way solenoid directional valve 11 under the action of load to realize hydraulic energy recovery.

[0154] Based on the above embodiments, in an optional embodiment of the present invention, the control method when the stick cylinder 18 and the boom cylinder operate simultaneously is as follows:

[0155] Determine the operating conditions of the boom cylinder 18 and the arm cylinder.

[0156] When the boom cylinder 18 is determined to be in the extended position, the first three-position four-way solenoid directional valve 16 is controlled to be in the working position that allows hydraulic oil to enter the rodless chamber of the boom cylinder 18. When the boom cylinder 18 is determined to be in the retracted position, the first three-position four-way solenoid directional valve 16 is controlled to be in the working position that allows hydraulic oil to enter the rod chamber of the boom cylinder 18.

[0157] When the boom cylinder is determined to be in the extended position, the second three-position four-way solenoid directional valve 17 is controlled to be in the working position that allows hydraulic oil to enter the rodless chamber of the boom cylinder. When the boom cylinder is determined to be in the retracted position, the second three-position four-way solenoid directional valve 17 is controlled to be in the working position that allows hydraulic oil to enter the rod chamber of the boom cylinder.

[0158] The hydraulic oil output from the control hydraulic pump 1 is split and supplied to the corresponding working chambers of the stick cylinder 18 and the boom cylinder to achieve synchronous movement of the stick and boom.

[0159] Determine whether the energy recovery conditions are met based on the state of charge of the energy storage device and / or the outlet pressure of the pump motor 4.

[0160] When the energy recovery conditions are met, the return oil from the control stick cylinder 18 and the boom cylinder merges and enters the pump motor 4 for energy recovery. Otherwise, the return oil from the control stick cylinder 18 returns to the hydraulic oil tank 21 through the second two-position three-way solenoid directional valve 13. The return oil from the control boom cylinder returns to the hydraulic oil tank 21 through the second relief valve 6.

[0161] Specifically, the control method for extending the boom cylinder 18 and the boom cylinder when they operate simultaneously includes the steps of combined boom and boom drive and energy recovery by the system.

[0162] When the stick and boom are driven in a combined manner, steps G1 to G2 are included.

[0163] G1. Determine whether the difference between the pressure in the rodless chamber and the pressure in the rod chamber of the boom cylinder 18 exceeds the ninth preset value of the boom.

[0164] G2. When it is determined that the pressure difference between the rodless chamber and the rod chamber of the stick cylinder 18 exceeds the ninth preset value of the stick, adjust the working positions of the first three-position four-way solenoid directional valve 16 and the second three-position four-way solenoid directional valve 17 to the right position. Open the first two-position two-way solenoid directional valve 10, open the third two-position two-way solenoid directional valve 22, and close the first two-position three-way solenoid directional valve 12. The hydraulic oil is diverted at the outlet of the first check valve 7 and flows to the rodless chambers of the stick cylinder 18, the first boom cylinder 19, and the second boom cylinder 20 respectively, so as to realize the combined drive of the excavator stick and boom.

[0165] When the boom and stick perform combined energy recovery, it includes steps H1 and H2.

[0166] H1. Determine if the SOC of the supercapacitor is less than the upper limit Scmax. Determine if the outlet pressure of pump motor 4 exceeds the tenth preset value.

[0167] H2. When it is determined that the SOC of the supercapacitor exceeds the upper limit Scmax, or the outlet pressure of the pump motor 4 exceeds the tenth preset value, the second two-position two-way solenoid directional valve 11 is closed so that the hydraulic oil in the boom and arm cylinders returns to the hydraulic oil tank 21.

[0168] Otherwise, close the second two-position three-way solenoid directional valve 13, open the second two-position two-way solenoid directional valve 11, and adjust the working positions of the first three-position four-way solenoid directional valve 16 and the second three-position four-way solenoid directional valve 17 so that the hydraulic oil in the boom and arm cylinders enters the pump motor 4 under load to achieve hydraulic energy recovery.

[0169] Preferably, the energy recovery assembly includes an integrated electric generator 3 and a pump motor 4. The inlet of the second overflow valve 6 is connected to the oil inlet of the pump motor 4. The outlet of the pump motor 4 is connected to the hydraulic oil tank 21.

[0170] First preset value = Third preset value = Sixth preset value = Seventh preset value.

[0171] Second preset value > Fourth preset value.

[0172] Fifth preset value = Eighth preset value = Tenth preset value.

[0173] The eighth and fifth preset values ​​depend on the maximum working pressure of pump motor 4, and the ninth preset value is used to start the cooperative operation.

[0174] The ninth preset value is greater than the second preset value.

[0175] The fourth preset value is greater than the first preset value.

[0176] The specific values ​​of each preset value shall be set by those skilled in the art based on the actual situation, and the present invention does not make specific settings in this regard.

[0177] During the energy recovery phase, based on the oil pressure (i.e., the load) in the rodless or rod chamber of the boom or stick cylinder 18, the system controls the speed and direction of the bidirectional pump motor 4 to convert the gravitational potential energy released during boom lowering and stick resetting into hydraulic energy. Furthermore, the hydraulic energy generated during boom lifting and stick lifting is transmitted to the pump motor 4, which then drives the motor to generate electricity and stores it in the supercapacitor. During the energy release and drive phase, based on the oil pressure (i.e., the load) in the rodless or rod chamber, the supercapacitor releases electrical energy to drive the pump motor 4, outputting high-pressure oil to assist the main hydraulic pump 1 in supplying oil to the cylinders, thereby achieving energy saving and oil replenishment. The control strategies for the pump motor 4 and the supercapacitor during energy storage and release are to be selected by those skilled in the art, and this invention does not impose specific limitations on them.

[0178] This invention discloses an energy recovery system for excavator boom and stick based on a pump motor 4. The system employs a bidirectional pump motor 4 unit to convert the gravitational potential energy released during boom lowering and stick resetting into hydraulic energy. Furthermore, the hydraulic energy generated during boom and stick lifting is transmitted to the pump motor 4, which then drives the motor to generate electricity, which is stored in a supercapacitor. This avoids the direct energy loss through throttling and overflow valves in traditional systems, significantly improving energy utilization. It effectively solves the problems of high energy consumption, low energy utilization, and unstable operation inherent in traditional excavator boom and stick drive systems.

[0179] The energy recovery system of the excavator boom and stick based on the pump motor 4 of the present invention includes multiple drive and energy recovery components, and each drive and energy recovery component is provided with a preset value of different size.

[0180] This invention discloses an energy recovery system for the boom and stick of an excavator based on a pump motor 4. The boom and stick employ independent electro-hydraulic drive circuits, using a two-position two-way solenoid valve and a three-position four-way solenoid directional valve to separate the energy recovery and drive oil circuits under different working conditions. Depending on the hydraulic oil pressure, the operating mode of the pump motor 4 is selected, along with the charging and discharging state of the pump / motor and supercapacitor. This enables bidirectional energy flow between the boom and stick during independent or coordinated operation, reducing oil energy loss in the oil circuit and maximizing energy recovery and reuse, thus improving energy utilization efficiency. The system relies on a motor to drive the pump motor 4 for energy recovery and auxiliary drive. During boom lifting and stick digging, the supercapacitor releases energy to drive the pump motor 4 to replenish the hydraulic system, thereby achieving efficient operation.

[0181] An energy recovery system for an excavator boom and stick based on a pump motor 4, according to an embodiment of the present invention, uses a supercapacitor as the core energy storage unit, and has the following significant advantages compared to traditional batteries or hydraulic accumulators:

[0182] During the energy recovery phase, the supercapacitor can achieve high-current, high-power rapid charging, efficiently capturing the gravitational potential energy released during instantaneous working conditions such as boom lowering and stick resetting, as well as the hydraulic energy generated during driving conditions such as boom raising and stick lifting, avoiding energy loss during the recovery process. During the drive phase, the supercapacitor can quickly release the stored electrical energy to drive pump motor 4 to output high-pressure hydraulic fluid, providing instantaneous auxiliary power for boom lifting and stick digging, effectively reducing the peak load on the main drive system.

[0183] Meanwhile, supercapacitors feature long charge-discharge cycle life, strong environmental adaptability, and low maintenance costs, making them suitable for excavator operation scenarios with frequent start-stop cycles and large load fluctuations, ensuring long-term stable system operation. Their balanced energy density and power density also make energy allocation more flexible under complex working conditions, further improving the excavator's overall energy efficiency and operational reliability.

[0184] Example 2: This application also provides an excavator that includes the energy recovery system for the excavator boom and stick based on the pump motor 4 described in any section of Example 1.

[0185] 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 energy recovery system for an excavator boom and stick based on a pump motor, characterized in that, The device includes a boom cylinder, a first three-position four-way solenoid directional valve adapted to switch the rod chamber and rodless chamber of the boom cylinder to a first two-position two-way solenoid directional valve and a second two-position three-way solenoid directional valve respectively, a boom cylinder, a second three-position four-way solenoid directional valve adapted to switch the rod chamber and rodless chamber of the boom cylinder to a first two-position three-way solenoid directional valve and a second two-position two-way solenoid directional valve respectively, a hydraulic pump adapted to supply hydraulic oil from the hydraulic tank to the first two-position two-way solenoid directional valve and a third two-position two-way solenoid directional valve, an electric motor driven by the hydraulic pump; a pump motor with pipelines connected between the second two-position two-way solenoid directional valve and the hydraulic tank, an electric generator driven by the pump motor, and an energy storage device electrically connected to the electric motor and the electric generator. The second two-position three-way solenoid directional valve is used to connect the hydraulic oil flowing out of the first three-position four-way solenoid directional valve to the second two-position two-way solenoid directional valve or the hydraulic oil tank. The pipeline of the first two-position two-way solenoid directional valve is connected to the third two-position two-way solenoid directional valve. The first two-position three-way solenoid directional valve is used to connect the third two-position two-way solenoid directional valve to the second three-position four-way solenoid directional valve, or to connect the second two-position two-way solenoid directional valve to the third two-position two-way solenoid directional valve. The boom lifting and lowering circuit includes a hydraulic oil tank, a hydraulic pump, a first check valve, a third two-position two-way solenoid directional valve, a first two-position three-way solenoid directional valve, a second three-position four-way solenoid directional valve, and the rodless chamber of the boom cylinder, which are connected in sequence. The auxiliary oil replenishment circuit includes a second two-position two-way solenoid directional valve, a second check valve, a first two-position three-way solenoid directional valve, and a third two-position two-way solenoid directional valve connected in sequence, and then connected in series between the outlet of the first check valve and the working port of the first two-position two-way solenoid directional valve.

2. The energy recovery system for the excavator boom and stick based on a pump motor according to claim 1, characterized in that, It also includes a first throttle valve connected between a first three-position four-way solenoid directional valve and a first two-position two-way solenoid directional valve, and a second throttle valve connected between a first two-position three-way solenoid directional valve and a second three-position four-way solenoid directional valve.

3. The energy recovery system for the excavator boom and stick based on a pump motor according to claim 1, characterized in that, It also includes a second check valve and a third check valve; The inlet of the third check valve is used to input the hydraulic oil flowing out of the second three-position four-way solenoid directional valve; The outlet of the third check valve, the inlet of the second check valve, and the inlet of the second overflow valve are all connected to the pump motor through the second two-position two-way solenoid directional valve. The outlet of the second check valve is connected to the first two-position three-way solenoid directional valve.

4. The energy recovery system for the excavator boom and stick based on a pump motor according to claim 1, characterized in that, It also includes a first relief valve; The inlet of the first relief valve is connected to the hydraulic pump; The outlet of the first relief valve is connected to the hydraulic oil tank.

5. The energy recovery system for the excavator boom and stick based on a pump motor according to claim 2, characterized in that, The control method when only the boom cylinder is active is as follows: Determine whether the boom cylinder is in the extended or retracted state; When the stick is determined to be in the extension condition, the first three-position four-way solenoid directional valve is controlled to be in the working position that allows hydraulic oil to enter the rodless chamber of the stick cylinder; when the stick is determined to be in the retraction condition, the first three-position four-way solenoid directional valve is controlled to be in the working position that allows hydraulic oil to enter the rod chamber of the stick cylinder. The flow area of ​​the first throttle valve is adjusted according to the pilot control pressure difference of the first throttle valve, and the hydraulic pump is controlled to supply oil to the corresponding working chamber of the boom cylinder; the difference between the pressure in the rodless chamber and the pressure in the rod chamber of the boom cylinder is used to determine whether it is necessary to supply oil by the hydraulic pump and the pump motor at the same time. When simultaneous oil supply is required, the hydraulic pump and pump motor are connected in parallel to supply oil to the corresponding working chamber of the boom cylinder; when simultaneous oil supply is not required, the hydraulic pump supplies oil to the corresponding working chamber of the boom cylinder alone, and determines whether the energy recovery conditions are met based on the state of charge of the energy storage device and / or the outlet pressure of the pump motor. When the energy recovery conditions are met, the pump motor is in hydraulic motor mode and the integrated electric generator is in generator mode, controlling the return oil from the boom cylinder to drive the pump motor to perform energy recovery; otherwise, the return oil from the boom cylinder returns to the hydraulic oil tank through the second two-position three-way solenoid directional valve.

6. The energy recovery system for the excavator boom and stick based on a pump motor according to claim 2, characterized in that, The control method when only the boom cylinder is in motion is as follows: Determine whether the boom cylinder is in the extended or retracted state; When the boom is determined to be in the extension condition, the second and third position four-way solenoid directional valve is controlled to be in the working position that allows hydraulic oil to enter the rodless chamber of the boom cylinder; when the boom is determined to be in the retraction condition, the second and third position four-way solenoid directional valve is controlled to be in the working position that allows hydraulic oil to enter the rod chamber of the boom cylinder. The flow area of ​​the second throttle valve is adjusted according to the pilot control pressure difference of the second throttle valve, and the hydraulic pump is controlled to supply oil to the corresponding working chamber of the boom cylinder. Determine whether the energy recovery conditions are met based on the state of charge of the energy storage device and / or the outlet pressure of the pump motor; When the energy recovery conditions are met, the pump motor is in hydraulic motor mode and the electric generator is in generator mode, controlling the return oil from the boom cylinder to enter the pump motor for energy recovery; otherwise, the return oil from the boom cylinder is controlled to return to the hydraulic oil tank through the second relief valve.

7. The energy recovery system for the excavator boom and stick based on a pump motor according to claim 2, characterized in that, The control method when the stick cylinder and boom cylinder operate simultaneously is as follows: Determine the operating conditions of the boom cylinder and the stick cylinder; When the boom cylinder is determined to be in the extended state, the first three-position four-way solenoid directional valve is controlled to be in the working position that allows hydraulic oil to enter the rodless chamber of the boom cylinder; when the boom cylinder is determined to be in the retracted state, the first three-position four-way solenoid directional valve is controlled to be in the working position that allows hydraulic oil to enter the rod chamber of the boom cylinder. When the boom cylinder is determined to be in the extended position, the second and third position four-way solenoid directional valve is controlled to be in the working position that allows hydraulic oil to enter the rodless chamber of the boom cylinder; when the boom cylinder is determined to be in the retracted position, the second and third position four-way solenoid directional valve is controlled to be in the working position that allows hydraulic oil to enter the rod chamber of the boom cylinder. The hydraulic oil output from the control hydraulic pump is split and supplied to the corresponding working chambers of the stick cylinder and boom cylinder respectively, so as to realize the synchronous movement of the stick and boom. Determine whether the energy recovery conditions are met based on the state of charge of the energy storage device and / or the outlet pressure of the pump motor; When the energy recovery conditions are met, the return oil from the control stick cylinder and boom cylinder merges and enters the pump motor for energy recovery; otherwise, the return oil from the control stick cylinder returns to the hydraulic oil tank through the second two-position three-way solenoid valve; the return oil from the control boom cylinder returns to the hydraulic oil tank through the second relief valve.

8. The energy recovery system for excavator boom and stick based on a pump motor according to any one of claims 1 to 7, characterized in that, There are two boom cylinders, namely the first boom cylinder and the second boom cylinder; the rodless chamber pipelines of the first boom cylinder and the second boom cylinder are connected; the rod chamber pipelines of the first boom cylinder and the second boom cylinder are connected. The energy storage device is set as a supercapacitor.

9. The energy recovery system for excavator boom and stick based on a pump motor according to any one of claims 1 to 7, characterized in that, The first three-position four-way solenoid directional valve is provided with working port A, working port B, working port C and working port D, and is configured such that working port A can be switched to be connected to one of working port B and working port C, and the other of working port B and working port C is connected to working port D; wherein, working port A is connected to the first two-position two-way solenoid directional valve; working port B is connected to the rodless chamber of the boom cylinder; and working port C is connected to the rod chamber of the boom cylinder. The second three-position four-way solenoid directional valve is provided with working port U, working port V, working port W and working port X, and is configured such that working port U can switch to be connected to one of working port V and working port W, and the other of working port V and working port W is connected to working port X; wherein, working port V is connected to the rodless chamber of the boom cylinder; working port W is connected to the rod chamber of the boom cylinder; and working port X is connected to the second two-position two-way solenoid directional valve and the second relief valve. The first two-position three-way solenoid directional valve is provided with working port R, working port S and working port T, and is configured such that working port R can be switched to be connected to working port S or working port T; wherein, working port R is connected to the third two-position two-way solenoid directional valve; working port S is connected to working port U; and working port T is connected to the second two-position two-way solenoid directional valve. The second two-position three-way solenoid directional valve is provided with working port G, working port J and working port H, and is configured such that working port G can be switched to be connected to working port J or working port H; wherein, working port G is connected to working port D; working port J is connected to hydraulic oil tank; and working port H is connected to the second two-position two-way solenoid directional valve. The first and second position two-way solenoid directional valve is provided with working port E and working port F, and is configured to be able to connect or disconnect; wherein, working port E is connected to the hydraulic pump; working port F is connected to working port A; The second two-position two-way solenoid directional valve is provided with working port K and working port L, and is configured to be able to connect or disconnect; wherein, working port K is connected to the second three-position four-way solenoid directional valve, working port T and the second relief valve; working port L is connected to the pump motor. The third two-position two-way solenoid valve is equipped with a working port P and a working port Q, and is configured to be able to connect or disconnect; wherein, the working port P is connected to the first two-position two-way solenoid valve and the hydraulic pump; the working port Q is connected to the working port R.

10. An excavator, characterized in that, An energy recovery system comprising a pump motor-based excavator boom and stick as described in any one of claims 1 to 9.

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