A novel closed pump-controlled asymmetric cylinder system for an electrically powered construction machine

Abstract

The application provides a novel closed pump control asymmetric cylinder system, which can recycle energy of the system under forward load working condition through bidirectional hydraulic pump motor and bidirectional variable speed servo motor to generate electricity to store energy in an electric energy storage unit, and the electric energy storage unit supplies power to the bidirectional variable speed servo motor and the bidirectional hydraulic pump motor to utilize energy under reverse load working condition. Meanwhile, the asymmetric hydraulic cylinder of the system has a third hydraulic cavity directly connected to a small closed pump control system, and energy recycling and utilization are carried out through separate control, and the small closed pump control system can be driven alone to actively control flow and pressure to assist in controlling the asymmetric hydraulic cylinder actuator, thereby improving the use performance of the system. Through the application, the energy utilization efficiency of the electric engineering machinery boom is improved, the wasted energy in the working process is recycled and utilized, and the load capacity and working performance of the boom are improved.

Description

Technical Field

[0001] This invention relates to the field of closed-loop pump control system technology, and more specifically, to a novel closed-loop pump control asymmetric cylinder system for electric engineering machinery. Background Technology

[0002] With the development of the national economy and the demands of national construction, engineering projects play a crucial role in the national economy, and excavators are an indispensable type of construction machinery in the rapid development of society. Traditional construction machinery widely adopts an engine-variable pump-multi-way valve-actuator drive system, which suffers from high energy consumption, high noise, low operating accuracy, and serious oil contamination, problems that urgently need to be addressed. At the same time, global energy shortages and the continuously increasing demand for excavators from various construction projects are placing increasingly higher demands on the technical specifications of excavators. Therefore, the development of excavator industry technology towards green, environmentally friendly, intelligent, and IoT-based technologies is an unchanging trend. However, existing multi-way valve controls inevitably produce throttling and overflow losses, and are insufficient in heavy-duty capacity and energy transfer efficiency, easily causing energy loss. During operation, high noise and low operating accuracy also affect the user experience. Summary of the Invention

[0003] This invention discloses a novel closed-loop pump-controlled asymmetric cylinder system for electric construction machinery. It has a simple structure and is easy to operate, aiming to improve the existing problems of high energy consumption, high noise, low operating accuracy and serious oil pollution in construction machinery.

[0004] The present invention adopts the following solution: a novel closed-loop pump-controlled asymmetric cylinder system for electric engineering machinery, comprising an electric energy storage unit, an oil tank, and further comprising: a first bidirectional variable speed servo motor, a first bidirectional hydraulic pump motor, an asymmetric hydraulic cylinder, a second bidirectional hydraulic pump motor, a second bidirectional variable speed servo motor, a first motor driver, a second motor driver, and a controller; wherein, the asymmetric hydraulic cylinder is adapted to connect to an external load of the system, and comprises a first chamber, a second chamber, and a third chamber;

[0005] The first bidirectional hydraulic pump motor includes a first oil port and a second oil port. The first oil port is connected to the first chamber of the asymmetric hydraulic cylinder to form a first chamber oil circuit, and the second oil port is connected to the second chamber of the asymmetric hydraulic cylinder to form a second chamber oil circuit. The third chamber of the asymmetric hydraulic cylinder is connected to the second bidirectional hydraulic pump motor to form a third chamber oil circuit. The second bidirectional hydraulic pump motor is connected to the second bidirectional variable speed servo motor, and the second bidirectional variable speed servo motor is electrically connected to the second motor driver. The first bidirectional variable speed servo motor is configured to control the asymmetric hydraulic cylinder's direction of motion and speed by controlling the flow rate and pressure of the first bidirectional hydraulic pump motor.

[0006] The energy storage unit is simultaneously connected to the first bidirectional variable speed servo motor and the second bidirectional variable speed servo motor. It is configured such that when the external load is under load, the first bidirectional variable speed servo motor, the second bidirectional variable speed servo motor, the first bidirectional hydraulic pump motor, and the second bidirectional hydraulic pump motor can rotate under the influence of the external load to generate electricity for the energy storage unit for energy recovery and storage. When the external load is under reverse load, the energy storage unit can supply power to the controller and motor driver to drive the first bidirectional variable speed servo motor and the second bidirectional variable speed servo motor to rotate. At this time, the controller and the second motor driver are configured to drive the second bidirectional variable speed servo motor to rotate, thereby applying pressure to the third chamber of the asymmetric cylinder, based on the operating conditions of the external load, to achieve high-load output from the asymmetric hydraulic cylinder.

[0007] Furthermore, the asymmetric hydraulic cylinder also includes a magnetostrictive displacement sensor and an extension rod, the extension rod being movably connected to the first and third chambers and adapted to be connected to electric engineering machinery to bear external loads of the system; the magnetostrictive displacement sensor is connected to the controller and the extension rod, and is configured to collect displacement data of the extension rod and transmit the data to the controller.

[0008] Furthermore, a first check valve and a second check valve connected to the oil tank are respectively connected in parallel on the first chamber oil circuit and the second chamber oil circuit of the first bidirectional hydraulic pump motor, and a first relief valve and a second relief valve connected to the oil tank are respectively connected in parallel on the first check valve and the second check valve.

[0009] Furthermore, a first two-position two-way solenoid valve is also connected in parallel on the first bidirectional hydraulic pump motor. The first two-position two-way solenoid valve is configured between the first chamber oil passage and the second chamber oil passage of the asymmetric hydraulic cylinder and is in the normally closed position.

[0010] Furthermore, a second two-position two-way solenoid valve is provided in the first chamber oil circuit and is in the normally open position; a third two-position two-way solenoid valve is provided in the second chamber oil circuit and is in the normally open position; and a fourth two-position two-way solenoid valve is provided in the third chamber oil circuit and is in the normally open position. The second, third, and fourth two-position two-way solenoid valves are configured to switch the on / off state of the first, second, and third chamber oil circuits respectively through opening and closing actions.

[0011] Furthermore, a third overflow valve connected in parallel to the oil tank is also provided in the third chamber oil circuit. The third overflow valve is configured to allow oil to flow from the third chamber into the oil tank when the pressure in the third chamber of the asymmetric hydraulic cylinder is overloaded.

[0012] Furthermore, the controller is electrically connected to the first motor driver and the second motor driver, and the first motor driver and the second motor driver are respectively electrically connected to the first bidirectional variable speed servo motor and the second bidirectional variable speed servo motor. The first bidirectional variable speed servo motor and the second bidirectional variable speed servo motor are adapted to provide speed feedback and current feedback to the first motor driver and the second motor driver, respectively.

[0013] Beneficial effects:

[0014] 1. This system uses an electric energy storage unit and a bidirectional variable speed servo motor for driving and energy recovery. The bidirectional variable speed servo motor is connected to a bidirectional hydraulic pump motor to control the flow and pressure. The forward and reverse rotation of the motor is controlled by the controller and motor driver to control the extension and retraction of the symmetrical hydraulic cylinder actuator. The forward and reverse rotation speed of the motor is controlled by the controller and motor driver to control the extension and retraction speed of the symmetrical hydraulic cylinder actuator.

[0015] 2. The asymmetric cylinder used in this system is equipped with a third chamber directly connected to a small pump control system, enabling independent energy recovery and load force control of the asymmetric cylinder according to working conditions. By identifying on-load and off-load conditions and controlling the two servo motors individually, energy exchange between the servo motors and the energy storage unit can be achieved, thus realizing energy recovery and utilization. It can also better match the working conditions for load force output. Unlike traditional closed-loop pump-controlled asymmetric cylinder systems, this new closed-loop pump-controlled asymmetric cylinder system solves the flow compensation problem existing in traditional closed-loop pump-controlled asymmetric cylinder systems by using a three-chamber hydraulic cylinder. Furthermore, the pressure of the third chamber can be actively controlled by a small closed-loop pump control system to assist in controlling the energy recovery and actuation of the asymmetric cylinder, resulting in significant improvements in energy utilization efficiency, actuation speed, and output force. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the novel closed-loop pump-controlled asymmetric cylinder system and its control principle according to an embodiment of the present invention;

[0017] Icons: 1. Electric energy storage unit; 2. First bidirectional variable speed servo motor; 3. First bidirectional hydraulic pump motor; 4. Oil tank; 5. First check valve; 6. Second check valve; 7. First relief valve; 8. Second relief valve; 9. First two-position two-way solenoid valve; 10. Second two-position two-way solenoid valve; 11. Third two-position two-way solenoid valve; 12. Magnetostrictive displacement sensor; 13. Asymmetric hydraulic cylinder; 14. Fourth two-position two-way solenoid valve; 15. Third relief valve; 16. Second bidirectional hydraulic pump motor; 17. Second bidirectional variable speed servo motor; 18. Second motor driver; 19. First motor driver; 20. Controller. Detailed Implementation

[0018] Example

[0019] Combination Figure 1 This embodiment provides a novel closed-loop pump-controlled asymmetric cylinder system for electric engineering machinery, including an electric energy storage unit 1, an oil tank 4, and further including: a first bidirectional variable speed servo motor 2, a first bidirectional hydraulic pump motor 3, an asymmetric hydraulic cylinder 13, a second bidirectional hydraulic pump motor 16, a second bidirectional variable speed servo motor 17, a first motor driver 19, a second motor driver 18, and a controller 20; wherein, the asymmetric hydraulic cylinder 13 is adapted to connect to an external load of the system, and includes a first chamber, a second chamber, and a third chamber;

[0020] The first bidirectional hydraulic pump motor 3 includes a first oil port and a second oil port. The first oil port is connected to the first chamber of the asymmetric hydraulic cylinder 13 to form a first chamber oil circuit, and the second oil port is connected to the second chamber of the asymmetric hydraulic cylinder 13 to form a second chamber oil circuit. The third chamber of the asymmetric hydraulic cylinder 13 is connected to the second bidirectional hydraulic pump motor 16 to form a third chamber oil circuit. The second bidirectional hydraulic pump motor 16 is connected to the second bidirectional variable speed servo motor 17, and the second bidirectional variable speed servo motor 17 is electrically connected to the second motor driver 18. The first bidirectional variable speed servo motor 2 is configured to control the asymmetric hydraulic cylinder 13's operating direction and operating speed by controlling the flow rate and pressure of the first bidirectional hydraulic pump motor 3.

[0021] The energy storage unit 1 is simultaneously connected to the first bidirectional variable speed servo motor 2 and the second bidirectional variable speed servo motor 17. It is configured such that when the external load is under load, the first bidirectional variable speed servo motor 2, the second bidirectional variable speed servo motor 17, the first bidirectional hydraulic pump motor 3, and the second bidirectional hydraulic pump motor 16 can rotate under the influence of the external load to generate electricity for the energy storage unit 1 for energy recovery and storage. When the external load is under reverse load, the energy storage unit 1 can supply power to the controller 20 and the motor driver to drive the first bidirectional variable speed servo motor 2 and the second bidirectional variable speed servo motor 17 to rotate. At this time, the controller 20 and the second motor driver 18 are configured to drive the second bidirectional variable speed servo motor 17 to rotate the second bidirectional hydraulic pump motor 16 according to the working conditions of the external load, thereby applying pressure to the third chamber of the asymmetric cylinder and achieving a large load output from the asymmetric hydraulic cylinder 13.

[0022] In this embodiment, the electric construction machinery may be excavators, elevators, or other machinery. For ease of description, this embodiment uses an excavator as an example, but it is not limited to excavators.

[0023] In this embodiment, the asymmetric hydraulic cylinder 13 further includes a magnetostrictive displacement sensor 12 and an extension rod. The extension rod is movably connected to the first and third chambers and is adapted to be connected to electric engineering machinery to bear external loads. The magnetostrictive displacement sensor 12 is connected to the controller 20 and the extension rod, and is configured to collect displacement data of the extension rod and transmit the data to the controller 20. Here, the extension rod is used to bear the load, and its working principle is as follows:

[0024] When the extension rod of the asymmetric hydraulic cylinder 13 extends upward and the load force is upward, the first bidirectional variable speed servo motor 2 is in a load-carrying condition (e.g., the excavator boom contacts the ground and the support body slowly descends). The first chamber of the asymmetric hydraulic cylinder 13 is a high-pressure chamber, and the second chamber is a low-pressure chamber. With the extension rod of the asymmetric hydraulic cylinder 13 extending upward, the hydraulic fluid, under the action of the external load, flows from the first chamber through the first bidirectional hydraulic pump motor 3 to the second chamber, simultaneously driving the first bidirectional hydraulic pump motor 3 and the first bidirectional variable speed servo motor 2 to rotate forward, generating electricity to power the energy storage unit 1 to complete the recovery of electrical energy. The second bidirectional variable speed servo motor 17 is also in a load-carrying condition at this time. Under the action of the external load, the hydraulic fluid flows from the oil tank 4 through the second bidirectional hydraulic pump motor 16 into the third chamber of the asymmetric hydraulic cylinder 13, driving the second bidirectional hydraulic pump motor 16 and the second variable speed servo motor to rotate forward, generating electricity to power the energy storage unit 1 to complete the recovery and storage of energy.

[0025] When the extension rod of the asymmetric hydraulic cylinder 13 retracts downward and the load force is upward, the first bidirectional variable speed servo motor 2 is in a reverse load condition (e.g., the excavator boom contacts the ground and the support body slowly lifts up, or the excavator boom contacts the ground and digs downward). At this time, the first chamber of the asymmetric hydraulic cylinder 13 is a high-pressure chamber, and the second chamber is a low-pressure chamber. Powered by the electric energy storage unit 1, under the control of the controller 20 and the first motor driver 19, the first bidirectional variable speed servo motor 2 and the first bidirectional hydraulic pump motor 3 rotate in opposite directions, causing the oil to flow from the second chamber through the first bidirectional hydraulic pump motor 3 to the first chamber, pushing the extension rod of the asymmetric hydraulic cylinder 13 to retract downward. The second bidirectional variable speed servo motor 17 is also in a reverse load condition at this time. Powered by the electric energy storage unit 1, under the control of the controller 20 and the second motor driver 18, the second bidirectional variable speed servo motor 17 and the second bidirectional hydraulic pump motor 16 rotate in opposite directions. Under the action of the second bidirectional hydraulic pump motor 16, the oil flows from the third chamber of the asymmetric hydraulic cylinder 13 through the second bidirectional hydraulic pump motor 16 into the oil tank 4, assisting the extension rod of the asymmetric hydraulic cylinder 13 to retract downward.

[0026] When the extension rod of the asymmetric hydraulic cylinder 13 retracts downwards and the load force is downwards, the first bidirectional variable speed servo motor 2 is in the load-following condition (e.g., the excavator boom lowers from high to low under no-load or load conditions). At this time, the first chamber of the asymmetric hydraulic cylinder 13 is the low-pressure chamber, and the second chamber is the high-pressure chamber. As the extension rod of the asymmetric hydraulic cylinder 13 retracts downwards, the hydraulic fluid flows from the second chamber through the first bidirectional hydraulic pump motor 3 to the first chamber under the action of the external load of the system. At the same time, it drives the first bidirectional hydraulic pump motor 3 and the first bidirectional variable speed servo motor 2 to rotate in opposite directions to generate electricity and supply the energy storage unit 1 to complete the recovery of electrical energy. The second bidirectional variable speed servo motor 17 is also in the load-following condition at this time. Under the action of the external load of the system, the hydraulic fluid flows from the third chamber of the asymmetric hydraulic cylinder 13 through the second bidirectional hydraulic pump motor 16 into the oil tank 4, driving the second bidirectional hydraulic pump motor 16 and the second variable speed servo motor to rotate in opposite directions to generate electricity and supply the energy storage unit 1 to complete the recovery and storage of energy.

[0027] When the extension rod of the asymmetric hydraulic cylinder 13 extends upward and the load force is downward, the first bidirectional variable speed servo motor 2 is in reverse load condition (e.g., the excavator boom is raised from low to high under no-load or load conditions). The first chamber of the asymmetric hydraulic cylinder 13 is a low-pressure chamber, and the second chamber is a high-pressure chamber. Powered by the electric energy storage unit 1, the first bidirectional variable speed servo motor 2 and the first bidirectional hydraulic pump motor 3 are driven to rotate forward under the control of the controller 20 and the first motor driver 19, causing the oil to flow from the first chamber through the first bidirectional hydraulic pump motor 3 to the second chamber, pushing the extension rod of the asymmetric hydraulic cylinder 13 upward. At this time, the second bidirectional variable speed servo motor 17 is also in reverse load condition. Powered by the electric energy storage unit 1, the second bidirectional variable speed servo motor 17 and the second bidirectional hydraulic pump motor 16 are driven to rotate forward under the control of the controller 20 and the second motor driver 18. Under the action of the second bidirectional hydraulic pump motor 16, the oil flows from the oil tank 4 through the second bidirectional hydraulic pump motor 16 into the third chamber of the asymmetric hydraulic cylinder 13, assisting the extension rod of the asymmetric hydraulic cylinder 13 to extend upward.

[0028] In this embodiment of the invention, a small closed-loop pump control system is provided. This system includes a fourth two-position two-way solenoid valve 14, a third relief valve 15, a second bidirectional hydraulic pump motor 16, a second bidirectional variable speed servo motor 17, and a second motor driver 18. The third relief valve 15 is connected in parallel to the third chamber oil circuit and is connected to the oil tank 4. The third relief valve 15 is configured to allow oil to flow from the third chamber into the oil tank 4 when the pressure in the third chamber of the asymmetric hydraulic cylinder 13 is overloaded. The third chamber of the asymmetric hydraulic cylinder 13 is directly connected to the small closed-loop pump control system. When the pressure in the third chamber of the asymmetric hydraulic cylinder 13 is overloaded, the third relief valve 15 operates to allow oil to flow from the third chamber of the asymmetric hydraulic cylinder 13 into the oil tank 4. Depending on the load conditions (forward and reverse), the controller 20 and the second motor driver 18 jointly control the speed, direction, and power generation of the second bidirectional variable speed servo motor 17 and the second bidirectional hydraulic pump motor 16.

[0029] In this embodiment, a first check valve 5 and a second check valve 6, connected to the oil tank 4, are respectively connected in parallel on the first and second chamber oil circuits of the first bidirectional hydraulic pump motor 3. A first relief valve 7 and a second relief valve 8, connected to the oil tank 4, are also respectively connected in parallel on the first and second check valves 5 and 6. When the excavator boom extends (retracts) to its maximum position or the load is too high, causing excessive pressure inside the novel closed-loop pump-controlled asymmetric cylinder system, hydraulic fluid will flow into the oil tank 4 via the first relief valve 7 and the second relief valve 8 to achieve overload protection and prevent damage to the system and components. Simultaneously, when the flow rate inside the novel closed-loop pump-controlled asymmetric cylinder system is insufficient, hydraulic oil in the oil tank 4 will flow into the system via the first check valve 5 and the second check valve 6 to replenish hydraulic fluid to the first or second chamber of the asymmetric hydraulic cylinder 13.

[0030] A first two-position two-way solenoid valve 9 is also connected in parallel on the first bidirectional hydraulic pump motor 3. The first two-position two-way solenoid valve 9 is located between the first chamber oil circuit and the second chamber oil circuit of the asymmetric hydraulic cylinder 13 and is normally closed. When the excavator is finished using or the new closed-loop pump-controlled asymmetric cylinder system is damaged and cannot work normally, the first two-position two-way solenoid valve 9 can be actively operated to unload the asymmetric hydraulic cylinder 13, allowing the extension rod of the asymmetric hydraulic cylinder 13 to return to its initial position, controlling the pressure balance of the first and second chambers of the asymmetric hydraulic cylinder 13 to prevent system damage.

[0031] In a preferred embodiment, a second two-position two-way solenoid valve 10 is provided on the first chamber oil circuit and is in the normally open position; a third two-position two-way solenoid valve 11 is provided on the second chamber oil circuit and is in the normally open position; and a fourth two-position two-way solenoid valve 14 is provided on the third chamber oil circuit and is in the normally open position. The second two-position two-way solenoid valve 10, the third two-position two-way solenoid valve 11, and the fourth two-position two-way solenoid valve 14 are configured to switch the on / off state of the first chamber oil circuit, the second chamber oil circuit, and the third chamber oil circuit respectively through opening and closing actions. When the power is off, the asymmetric hydraulic cylinder 13 is fully connected to the first chamber oil circuit, the second chamber oil circuit, and the small closed-loop pump control system to ensure that the novel closed-loop pump control asymmetric cylinder system can operate normally. When the excavator boom needs to be suspended at a certain position due to working conditions, the system supplies power to simultaneously switch the second two-position two-way solenoid valve 10, the third two-position two-way solenoid valve 11, and the fourth two-position two-way solenoid valve 14 to the closed position, thereby cutting off the first chamber oil circuit, the second chamber oil circuit, and the small pump control system, so that the asymmetric hydraulic cylinder 13 is in a pressure-holding state.

[0032] The controller 20 is electrically connected to the first motor driver 19 and the second motor driver 18. The first motor driver 19 and the second motor driver 18 are respectively electrically connected to the first bidirectional variable speed servo motor 2 and the second bidirectional variable speed servo motor 17. The first bidirectional variable speed servo motor 2 and the second bidirectional variable speed servo motor 17 are adapted to provide speed feedback and current feedback to the first motor driver 19 and the second motor driver 18, respectively.

[0033] This novel closed-loop pump-controlled asymmetric cylinder system primarily controls the asymmetric hydraulic cylinder 13's direction and speed by controlling the rotation and speed of the first bidirectional variable-speed servo motor 2 and the second bidirectional variable-speed servo motor 17. The control system of this novel closed-loop pump-controlled asymmetric cylinder system includes a controller 20 and a first motor driver 19 and a second motor driver 18. When a target signal is input to the controller 20, the controller 20 automatically analyzes and processes the data, sending it to the first motor driver 19 and the second motor driver 18 to control the rotation and speed of the first and second bidirectional variable-speed motors. Simultaneously, the controller receives displacement and velocity signals from the magnetostrictive displacement sensor 12 installed on the asymmetric hydraulic cylinder 13 and sends this feedback data to the controller 20 to complete negative feedback control. The controller 20 independently controls the first bidirectional variable-speed servo motor 2 and the second bidirectional variable-speed servo motor 17 based on the excavator's operating conditions and working mode to achieve optimal performance.

[0034] The novel closed-loop pump-controlled asymmetric cylinder system in this invention can recover energy under on-load conditions. Energy is stored in the energy storage unit 1 by generating electricity through a bidirectional hydraulic pump motor and a bidirectional variable-speed servo motor. Under off-load conditions, the energy storage unit 1 supplies power to the bidirectional variable-speed servo motor and the bidirectional hydraulic pump motor for energy utilization. Simultaneously, the asymmetric hydraulic cylinder 13 of this system has a third hydraulic chamber directly connected to a small closed-loop pump-controlled system. Energy recovery and utilization are achieved through independent control. Furthermore, the small closed-loop pump-controlled system can be independently driven to actively control flow and pressure to assist in controlling the actuator of the asymmetric hydraulic cylinder 13, thereby improving system performance. This invention improves the energy utilization efficiency of the electric engineering machinery boom, realizing the recovery and utilization of energy wasted during operation, while simultaneously enhancing the boom's load capacity and working performance.

[0035] It should be understood that the above are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions that fall within the scope of the present invention are within the scope of protection of the present invention.

[0036] The accompanying drawings used in the above description of the embodiments only illustrate certain embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

Claims

1. A closed pump controlled asymmetric cylinder system of an electrically powered working machine, comprising an electrical energy storage unit, an oil tank, characterized in that, Also comprising: a first bidirectional variable speed servo motor, a first bidirectional hydraulic pump motor, an asymmetric hydraulic cylinder, a second bidirectional hydraulic pump motor, a second bidirectional variable speed servo motor, a first motor driver, a second motor driver and a controller; wherein, the asymmetric hydraulic cylinder is adapted to connect an external load of the system, comprising a first cavity, a second cavity and a third cavity; the first bidirectional hydraulic pump motor comprises a first oil port and a second oil port, and the first oil port is in communication with the first cavity of the asymmetric hydraulic cylinder to form a first cavity oil circuit, the second oil port is in communication with the second cavity of the asymmetric hydraulic cylinder to form a second cavity oil circuit, the third cavity of the asymmetric hydraulic cylinder is communicated to the second bidirectional hydraulic pump motor to form a third cavity oil circuit, and the second bidirectional hydraulic pump motor is connected to the second bidirectional variable speed servo motor, and the second bidirectional variable speed servo motor is electrically connected to the second motor driver; the first bidirectional variable speed servo motor is configured to control the actuating direction and speed of the asymmetric hydraulic cylinder by controlling the flow and pressure of the first bidirectional hydraulic pump motor; the electric energy storage unit is connected to the first bidirectional variable speed servo motor and the second bidirectional variable speed servo motor, and is configured to, when the external load of the system is in a forward load condition, the first bidirectional variable speed servo motor, the second bidirectional variable speed servo motor and the first bidirectional hydraulic pump motor can rotate under the action of the external load to generate electricity to the electric energy storage unit for energy recovery and storage; when the external load of the system is in a reverse load condition, the electric energy storage unit can supply power to the controller and the first motor driver, the second motor driver to drive the first bidirectional variable speed servo motor and the second bidirectional variable speed servo motor to rotate; At this time, the controller and the second motor driver are configured to drive the second bidirectional variable speed servo motor to rotate the second bidirectional hydraulic pump motor to give the third cavity of the asymmetric cylinder pressure, realizing the large load output of the asymmetric hydraulic cylinder; the asymmetric hydraulic cylinder further comprises a magnetostrictive displacement sensor and an extension rod, the extension rod is movably connected to the first cavity and the third cavity, and is adapted to be connected with an electric engineering machinery to receive the external load of the system; the magnetostrictive displacement sensor is connected to the controller and the extension rod, and is configured to collect displacement data of the extension rod and transmit the data to the controller.

2. A closed pump controlled asymmetric cylinder system of an electrically powered working machine according to claim 1, characterized in that, First and second one-way valves connected to the oil tank are respectively arranged in parallel on the first and second cavity oil circuits of the first bidirectional hydraulic pump motor, and first and second overflow valves connected to the oil tank are respectively arranged in parallel on the first and second one-way valves.

3. A closed pump controlled asymmetric cylinder system of an electrically powered working machine according to claim 2, characterized in that, A first two-position two-way electromagnetic valve is further arranged in parallel on the first bidirectional hydraulic pump motor, and the first two-position two-way electromagnetic valve is arranged between the first and second cavity oil circuits of the asymmetric hydraulic cylinder and is in a normally closed position.

4. A closed pump controlled asymmetric cylinder system of an electrically powered working machine according to claim 1, characterized in that, A second two-position two-way electromagnetic valve is arranged on the first cavity oil path and is in a normally open position, a third two-position two-way electromagnetic valve is arranged on the second cavity oil path and is in a normally open position, and a fourth two-position two-way electromagnetic valve is arranged on the third cavity oil path and is in a normally open position; the second, third, and fourth two-position two-way electromagnetic valves are configured to switch the first, second, and third cavity oil paths on and off through opening and closing actions.

5. A closed pump controlled asymmetric cylinder system of an electrically powered working machine according to claim 1, characterized in that, A third overflow valve is also arranged in parallel on the third cavity oil path and is connected to the oil tank; the third overflow valve is configured to allow oil to flow from the third cavity to the oil tank when the third cavity pressure of the asymmetric hydraulic cylinder is overloaded.

6. A closed pump controlled asymmetric cylinder system of an electrically powered working machine according to claim 1, characterized in that, The controller is electrically connected to the first motor driver and the second motor driver, the first motor driver and the second motor driver are respectively electrically connected to the first bidirectional variable-speed servo motor and the second bidirectional variable-speed servo motor, and the first bidirectional variable-speed servo motor and the second bidirectional variable-speed servo motor are adapted to provide speed feedback and current feedback to the first motor driver and the second motor driver, respectively.

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