A pump-controlled electro-hydraulic system based on a double-shaft extension motor and a control method thereof

Abstract

This invention discloses a pump-controlled electro-hydraulic system and its control method based on a dual-shaft extension motor. The system includes an oil source, two pump motors, a dual-shaft extension motor, two safety valves, a hydraulic lock, two pressure sensors, a hydraulic actuator, a displacement sensor, a working condition identification and control unit, and a drive and power generation unit. The drive and power generation unit is connected to the dual-shaft extension motor. Each end of the extension shaft of the dual-shaft extension motor is connected to a pump motor. The two oil ports of the pump motors are connected to the oil source and the forward oil inlet of the hydraulic lock, respectively. The forward oil outlet of the hydraulic lock is connected to the hydraulic actuator, forming the control loop of the hydraulic actuator. The working condition identification and control unit identifies the working condition of the hydraulic actuator and adjusts the speed of the dual-shaft extension motor and the displacement of the pump motors according to the working condition characteristics to control the output displacement of the hydraulic actuator. Simultaneously, energy is recovered when the working condition is exceeded. This invention can independently control the two chambers of the hydraulic actuator, recover energy, has a simple structure, and high system energy efficiency.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic engineering, specifically relating to a pump-controlled electro-hydraulic system based on a dual-shaft extension motor and its control method. Background Technology

[0002] Hydraulic drive systems are widely used in industrial production due to their high power density and large output force or torque. Currently, hydraulic drive systems mainly control the action of actuators through hydraulic valves. Although valve-controlled systems are mature, reliable, and easy to install, they suffer from significant throttling losses and low system efficiency, typically only around 30%, making it difficult to meet the demands of "green" development. Pump-controlled systems, on the other hand, directly drive actuators through hydraulic pumps, completely eliminating throttling losses and achieving high system efficiency. This is considered an effective way to achieve "green" hydraulic drive systems and one of the future development directions in the field of hydraulic drives.

[0003] Currently, pump-controlled systems can effectively replace valve-controlled systems when driving symmetrical actuators. However, compared to asymmetrical actuators, symmetrical actuators are less commonly used in industry. Because the two chambers of an asymmetrical actuator have different working areas, the flow rates in the two chambers are asymmetrical. In pump-controlled asymmetrical actuator systems, a makeup oil circuit is usually required to balance the asymmetrical flow. This makeup oil circuit not only complicates the system structure and increases the difficulty of control but also reduces the system's energy efficiency. This "flow imbalance problem" is one of the main factors restricting the industrial application of pump-controlled asymmetrical actuator systems. Summary of the Invention

[0004] To address the "flow imbalance problem" in pump-controlled asymmetric actuator systems, this invention proposes a pump-controlled electro-hydraulic system and its control method based on a dual-shaft extension motor. This system features a simple structure, high integration, and high energy efficiency.

[0005] The objective of this invention is achieved through the following technical solution: A pump-controlled electro-hydraulic system based on a dual-shaft extension motor includes an oil source, a first safety valve, a first pump motor, a dual-shaft extension motor, a second pump motor, a second safety valve, a hydraulic lock, a first pressure sensor, a hydraulic actuator, a second pressure sensor, a displacement sensor, a working condition identification and control unit, and a drive and power generation unit. The drive and power generation unit is connected to the dual-shaft extension motor. One end of the extension shaft of the dual-shaft extension motor is fixedly connected to the shaft of the first pump motor, and the other end is fixedly connected to the shaft of the second pump motor. One oil port of the first pump motor is connected to an oil source via a pipeline, and the other oil port is connected to the positive oil inlet A1 of the hydraulic lock and the high-pressure oil port P of the first safety valve via pipelines. One oil port of the second pump motor is connected to the oil source via a pipeline, and the other oil port is connected to the positive oil inlet A2 of the hydraulic lock and the high-pressure oil port P of the second safety valve via pipelines. The first safety valve and the second safety valve... The return port T is connected to the oil source via a pipeline; the positive oil outlet B1 of the hydraulic lock is connected to one oil port of the hydraulic actuator via a pipeline, making it communicate with the rod chamber of the hydraulic actuator; the positive oil outlet B2 of the hydraulic lock is connected to the other oil port of the hydraulic actuator via a pipeline, making it communicate with the rodless chamber of the hydraulic actuator; the first pressure sensor is installed on the rodless chamber of the hydraulic actuator, and the second pressure sensor is installed on the rod chamber of the hydraulic actuator; a displacement sensor 11 is installed on the piston rod of the hydraulic actuator, and the piston rod of the hydraulic actuator is externally connected to a load.

[0006] Furthermore, both the first pump motor and the second pump motor are selected from four-quadrant pumps or two-quadrant pumps.

[0007] Furthermore, the power supply unit is an energy storage element or a power grid.

[0008] Furthermore, the working condition identification and control unit has a built-in working condition identification algorithm and a control algorithm. The working condition identification algorithm is used to determine the working condition of the hydraulic actuator based on the received sensor signals and control command signals. The control algorithm is used to generate displacement control commands for the first pump motor and the second pump motor, as well as speed commands for the dual-shaft extension motor, based on the received working condition signals, sensor signals, and control commands, thereby realizing the control of the output displacement of the hydraulic actuator.

[0009] A control method for a pump-controlled electro-hydraulic system based on a dual-shaft extension motor, wherein the hydraulic actuator has four working conditions: impedance extension, impedance retraction, over-extension, and over-retraction. When the hydraulic actuator is in the resistive extension condition, the first pump motor is in pump mode and the second pump motor is in motor mode. The condition identification and control unit first generates the displacement command of the first pump motor based on the signals from the displacement sensor, the signals from the first and second pressure sensors in both chambers, and the displacement command input by the operator. Then, it generates the speed command of the dual-shaft extension motor based on the displacement of the first pump motor and the displacement command input by the operator, thereby controlling the output displacement of the hydraulic actuator. At the same time, it generates the displacement command of the second pump motor based on the signals from the first and second pressure sensors in both chambers and the pressure command input by the operator, thereby controlling the back pressure of the hydraulic actuator and ensuring the operating rigidity of the system. When the hydraulic actuator is in the impedance retraction condition, the second pump motor is in pump mode and the first pump motor is in motor mode. The condition identification and control unit first generates the displacement command of the second pump motor based on the signals from the displacement sensor, the signals from the first and second pressure sensors in both chambers, and the displacement command input by the operator. Then, it generates the speed command of the dual-shaft extension motor based on the displacement of the second pump motor and the displacement command input by the operator, thereby controlling the output displacement of the hydraulic actuator. At the same time, it generates the displacement command of the first pump motor based on the signals from the first and second pressure sensors and the pressure command input by the operator, thereby controlling the back pressure of the hydraulic actuator and ensuring the operating rigidity of the system. When the hydraulic actuator is in overextended operation, the second pump motor is in motor mode and the first pump motor is in pump mode. The operation condition identification and control unit first generates a displacement command for the second pump motor based on the signals from the displacement sensor, the signals from the first and second pressure sensors in both chambers, and the displacement command input by the operator. Then, it generates a speed command for the dual-shaft extension motor based on the displacement of the second pump motor and the displacement command input by the operator, thereby controlling the output displacement of the hydraulic actuator and recovering the overload force to generate regenerative torque. When the regenerative torque is less than the torque required by the first pump motor, the regenerative torque is used to assist the dual-shaft extension motor in driving the first pump motor. When the regenerative torque is greater than the torque required by the first pump motor, part of the regenerative torque is used to drive the first pump motor, and the excess is used to drive the dual-shaft extension motor to generate electricity, which is then stored in the power supply unit through the drive and power generation unit. At the same time, the operation condition identification and control unit generates a displacement command for the first pump motor based on the signals from the first and second pressure sensors and the pressure command input by the operator, thereby controlling the inlet oil pressure of the hydraulic actuator and ensuring the operating rigidity of the system. When the hydraulic actuator is in over-retraction mode, the first pump motor is in motor mode and the second pump motor is in pump mode. The condition identification and control unit first generates a displacement command for the first pump motor based on the signals from the displacement sensor, the signals from the first and second pressure sensors in both chambers, and the displacement command input by the operator. Then, it generates a speed command for the dual-shaft extension motor based on the displacement of the first pump motor and the displacement command input by the operator, thereby controlling the output displacement of the hydraulic actuator and recovering the overload force to generate regenerative torque. When the regenerative torque is less than the torque required by the second pump motor, the regenerative torque is used to assist the dual-shaft extension motor in driving the second pump motor. When the regenerative torque is greater than the torque required by the second pump motor, part of the regenerative torque is used to drive the second pump motor, and the excess is used to drive the dual-shaft extension motor to generate electricity, which is then stored in the power supply unit through the drive and generation unit. At the same time, the condition identification and control unit generates a displacement command for the second pump motor based on the signals from the first and second pressure sensors and the pressure command input by the operator, thereby controlling the oil inlet pressure of the hydraulic actuator and ensuring the operating rigidity of the system.

[0010] The beneficial effects of this invention are as follows: 1. The pump-controlled electro-hydraulic system and its control method based on a dual-shaft extension motor proposed in this invention do not require a replenishment circuit when driving an asymmetric hydraulic actuator. The system has a simple structure and low implementation cost.

[0011] 2. This invention achieves decoupled control of the two chambers of the hydraulic actuator through a dual-shaft extension motor and two pump motors, fundamentally solving the "flow imbalance problem" in the pump-controlled asymmetric hydraulic actuator system, reducing the difficulty of system control, and improving the system's operating rigidity.

[0012] 3. Under overload conditions, one of the first pump motor and the second pump motor is in pump mode and the other is in motor mode. The pump motor in motor mode can convert the overload load into regenerative torque, realize energy recovery, and improve the energy efficiency of the system. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the pump-controlled electro-hydraulic system and its control method based on a dual-shaft extension motor, according to an embodiment of the present invention.

[0014] In the diagram: 1-oil source, 2-first safety valve, 3-first pump motor, 4-dual shaft extension motor, 5-second pump motor, 6-second safety valve, 7-hydraulic lock, 8-first pressure sensor, 9-hydraulic actuator, 10-second pressure sensor, 11-displacement sensor, 12-load, 13-operating condition identification and control unit, 14-power supply unit, 15-drive and power generation unit. Detailed Implementation

[0015] The present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments. The purpose and effects of the present invention will become clearer. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0016] like Figure 1 As shown, the pump-controlled electro-hydraulic system based on a dual-shaft extension motor in this embodiment of the invention includes an oil source 1, a first safety valve 2, a first pump motor 3, a dual-shaft extension motor 4, a second pump motor 5, a second safety valve 6, a hydraulic lock 7, a first pressure sensor 8, a hydraulic actuator 9, a second pressure sensor 10, a displacement sensor 11, a working condition identification and control unit 13, and a drive and power generation unit 15.

[0017] The drive and power generation unit 15 is connected to the dual-shaft extension motor 4. When the system is working, the drive and power generation unit 15 also requires an external power supply unit 14. One end of the extension shaft of the dual-shaft extension motor 4 is connected to the shaft of the first pump motor 3 via a coupling, and the other end is connected to the shaft of the second pump motor 5 via a coupling. One oil port of the first pump motor 3 is connected to the oil source 1 via a pipeline; the other oil port is connected to the forward oil inlet A1 of the hydraulic lock 7 and the high-pressure oil port P of the first safety valve 2 via pipelines. One oil port of the second pump motor 5 is connected to the oil source 1 via a pipeline, and the other oil port is connected to the forward oil inlet A2 of the hydraulic lock 7 and the second safety valve 6 via pipelines. The high-pressure oil port P is connected to the oil source. The return oil ports T of the first safety valve 2 and the second safety valve 6 are both connected to the oil source through pipelines. The forward oil outlet B1 of the hydraulic lock 7 is connected to one oil port of the hydraulic actuator 9 through a pipeline, so that it is connected to the rod chamber of the hydraulic actuator 9. The forward oil outlet B2 of the hydraulic lock 7 is connected to another oil port of the hydraulic actuator 9 through a pipeline, so that it is connected to the rodless chamber of the hydraulic actuator 9. A first pressure sensor 8 is installed on the rodless chamber of the hydraulic actuator 9, a second pressure sensor 10 is installed on the rod chamber, and a displacement sensor 11 is installed on the piston rod of the hydraulic actuator 9. An external load 12 is connected to the piston rod of the hydraulic actuator 9.

[0018] In this embodiment, the first pump motor 3 and the second pump motor 5 can be four-quadrant pumps or two-quadrant pumps. The hydraulic lock 7 can also be any other valve assembly with hydraulic locking function. The energy source for the power supply unit 14 can be either an energy storage device or the power grid.

[0019] Combination Figure 1The following describes the control method of the pump-controlled electro-hydraulic system based on a dual-shaft extension motor according to an embodiment of the present invention: The hydraulic actuator 9 has four operating conditions: impedance extension, impedance retraction, overshoot extension, and overshoot retraction. At any given moment during operation, the hydraulic actuator can only be in one of these four conditions. The operating condition identification and control unit 13 has a built-in operating condition identification algorithm and a control algorithm. The operating condition identification algorithm determines the operating condition of the hydraulic actuator 9 based on received sensor signals and control command signals. The control algorithm generates displacement control commands for the first pump motor 3 and the second pump motor 5, and a speed command for the dual-shaft extension motor 4, based on the received operating condition signals, sensor signals, and control commands, thereby controlling the output displacement and pressure of the two chambers of the hydraulic actuator 9.

[0020] Therefore, in another embodiment of the present invention, a control method for a pump-controlled electro-hydraulic system based on a dual-shaft extension motor is provided, the method comprising the following steps: When the hydraulic actuator 9 is in the resistance extension condition, the first pump motor 3 is in pump mode and the second pump motor is in motor mode. The condition identification and control unit 13 first generates the displacement command of the first pump motor 3 based on the signal of the displacement sensor 11, the signals of the first pressure sensor 8 and the second pressure sensor 10 of the two chambers, and the displacement command input by the operator. Then, it generates the speed command of the dual-shaft extension motor 4 based on the displacement of the first pump motor 3 and the displacement command input by the operator, thereby controlling the output displacement of the hydraulic actuator 9. At the same time, it generates the displacement command of the second pump motor 5 based on the signals of the first pressure sensor 8 and the second pressure sensor 10 of the two chambers and the pressure command input by the operator, thereby controlling the back pressure of the hydraulic actuator 9 and ensuring the operating rigidity of the system. When the hydraulic actuator 9 is in the impedance retraction condition, the second pump motor is in pump mode and the first pump motor is in motor mode. The condition identification and control unit 13 first generates the displacement command of the second pump motor 5 based on the signal of the displacement sensor 11, the signals of the first pressure sensor 8 and the second pressure sensor 10 of the two chambers, and the displacement command input by the operator; then, it generates the speed command of the dual-shaft extension motor 4 based on the displacement of the second pump motor 5 and the displacement command input by the operator, thereby controlling the output displacement of the hydraulic actuator 9; at the same time, it generates the displacement command of the first pump motor 3 based on the signals of the first pressure sensor 8 and the second pressure sensor 10 and the pressure command input by the operator, thereby controlling the back pressure of the hydraulic actuator 9 and ensuring the operating rigidity of the system. When the hydraulic actuator 9 is in over-extension mode, the second pump motor 5 is in motor mode and the first pump motor is in pump mode. The condition recognition and control unit 13 first generates a displacement command for the second pump motor 5 based on the signal from the displacement sensor 11, the signals from the first pressure sensor 8 and the second pressure sensor 10 in both chambers, and the displacement command input by the operator. Then, it generates a speed command for the dual-shaft extension motor 4 based on the displacement of the second pump motor 5 and the displacement command input by the operator, thereby controlling the output displacement of the hydraulic actuator 9 and recovering the overload force to generate regenerative torque. When the regenerative torque is less than that of the first pump motor... When the required torque is 3, the regenerated torque is used to assist the dual-shaft extension motor 4 in driving the first pump motor 3; when the regenerated torque is greater than the required torque of the first pump motor 3, part of the regenerated torque is used to drive the first pump motor 3, and the excess part is used to drive the dual-shaft extension motor 4 to generate electricity, and the electrical energy is stored in the power supply unit 14 through the drive and power generation unit 15; at the same time, the working condition identification and control unit 13 generates the displacement command of the first pump motor 3 according to the signals of the first pressure sensor 8, the second pressure sensor 10 and the pressure command input by the operator, so as to realize the control of the oil inlet pressure of the hydraulic actuator 9 and ensure the operating rigidity of the system.

[0021] When the hydraulic actuator 9 is in over-retraction mode, the first pump motor 3 is in motor mode and the second pump motor is in pump mode. The condition recognition and control unit 13 first generates a displacement command for the first pump motor 3 based on the signal from the displacement sensor 11, the signals from the first pressure sensor 8 and the second pressure sensor 10 in both chambers, and the displacement command input by the operator. Then, it generates a speed command for the dual-shaft extension motor 4 based on the displacement of the first pump motor 3 and the displacement command input by the operator, thereby controlling the output displacement of the hydraulic actuator 9 and recovering the overload force to generate regenerative torque. When the regenerative torque is less than that of the second pump motor... When the required torque is 5, the regenerated torque is used to assist the dual-shaft extension motor 4 in driving the second pump motor 5. When the regenerated torque is greater than the required torque of the second pump motor 5, part of the regenerated torque is used to drive the second pump motor 5, and the excess part is used to drive the dual-shaft extension motor 4 to generate electricity. The electrical energy is stored in the power supply unit 14 through the drive and power generation unit 15. At the same time, the working condition identification and control unit 13 generates the displacement command of the second pump motor 5 according to the signals of the first pressure sensor 8, the second pressure sensor 10 and the pressure command input by the operator, so as to realize the control of the oil inlet pressure of the hydraulic actuator 9 and ensure the operating rigidity of the system.

[0022] It will be understood by those skilled in the art that the above descriptions are merely preferred examples of the invention and are not intended to limit the invention. Although the invention has been described in detail with reference to the foregoing examples, those skilled in the art can still modify the technical solutions described in the foregoing examples or make equivalent substitutions for some of the technical features. All modifications and equivalent substitutions made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A control method for a pump-controlled electro-hydraulic system based on a dual-shaft extension motor, characterized in that, The pump-controlled electro-hydraulic system based on a dual-shaft extension motor includes an oil source, a first safety valve, a first pump motor, a dual-shaft extension motor, a second pump motor, a second safety valve, a hydraulic lock, a first pressure sensor, a hydraulic actuator, a second pressure sensor, a displacement sensor, a working condition identification and control unit, and a drive and power generation unit. The drive and power generation unit is connected to the dual-shaft extension motor. One end of the extension shaft of the dual-shaft extension motor is fixedly connected to the shaft of the first pump motor, and the other end is fixedly connected to the shaft of the second pump motor. One oil port of the first pump motor is connected to an oil source via a pipeline, and the other oil port is connected to the positive oil inlet A1 of the hydraulic lock and the high-pressure oil port P of the first safety valve via pipelines. One oil port of the second pump motor is connected to the oil source via a pipeline, and the other oil port is connected to the positive oil inlet A2 of the hydraulic lock and the high-pressure oil port P of the second safety valve via pipelines. The first safety valve and the second safety valve... The return port T is connected to the oil source via a pipeline; the positive oil outlet B1 of the hydraulic lock is connected to one oil port of the hydraulic actuator via a pipeline, making it communicate with the rod chamber of the hydraulic actuator; the positive oil outlet B2 of the hydraulic lock is connected to the other oil port of the hydraulic actuator via a pipeline, making it communicate with the rodless chamber of the hydraulic actuator; the first pressure sensor is installed on the rodless chamber of the hydraulic actuator, and the second pressure sensor is installed on the rod chamber of the hydraulic actuator; a displacement sensor 11 is installed on the piston rod of the hydraulic actuator, and the piston rod of the hydraulic actuator is externally connected to a load; The hydraulic actuator has four working conditions: resistance extension, resistance retraction, over-extension, and over-retraction. When the hydraulic actuator is in the resistive extension condition, the first pump motor is in pump mode and the second pump motor is in motor mode. The condition identification and control unit first generates the displacement command of the first pump motor based on the signals from the displacement sensor, the signals from the first and second pressure sensors in both chambers, and the displacement command input by the operator. Then, it generates the speed command of the dual-shaft extension motor based on the displacement of the first pump motor and the displacement command input by the operator, thereby controlling the output displacement of the hydraulic actuator. At the same time, it generates the displacement command of the second pump motor based on the signals from the first and second pressure sensors in both chambers and the pressure command input by the operator, thereby controlling the back pressure of the hydraulic actuator and ensuring the operating rigidity of the system. When the hydraulic actuator is in the impedance retraction condition, the second pump motor is in pump mode and the first pump motor is in motor mode. The condition identification and control unit first generates the displacement command of the second pump motor based on the signals from the displacement sensor, the signals from the first and second pressure sensors in both chambers, and the displacement command input by the operator. Then, it generates the speed command of the dual-shaft extension motor based on the displacement of the second pump motor and the displacement command input by the operator, thereby controlling the output displacement of the hydraulic actuator. At the same time, it generates the displacement command of the first pump motor based on the signals from the first and second pressure sensors and the pressure command input by the operator, thereby controlling the back pressure of the hydraulic actuator and ensuring the operating rigidity of the system. When the hydraulic actuator is in overextended working condition, the second pump motor is in motor mode and the first pump motor is in pump mode. The working condition identification and control unit first generates a displacement command for the second pump motor based on the signals from the displacement sensor, the signals from the first and second pressure sensors in the two chambers, and the displacement command input by the operator. Then, it generates a speed command for the dual-shaft extension motor based on the displacement of the second pump motor and the displacement command input by the operator, thereby controlling the output displacement of the hydraulic actuator and recovering excess load force to generate regenerative torque. When the regenerative torque is less than the torque required by the first pump motor, the regenerative torque is used to assist the dual-shaft extension motor in driving the first pump motor. When the regenerative torque is greater than the torque required by the first pump motor, part of the regenerative torque is used to drive the first pump motor, and the excess part is used to drive the dual-shaft extension motor to generate electricity, which is then stored in the power supply unit through the drive and power generation unit. At the same time, the working condition identification and control unit generates the displacement command of the first pump motor based on the signals from the first pressure sensor and the second pressure sensor and the pressure command input by the operator, so as to control the oil inlet pressure of the hydraulic actuator and ensure the operating rigidity of the system. When the hydraulic actuator is in the over-retracted working condition, the first pump motor is in motor mode and the second pump motor is in pump mode. The working condition identification and control unit first generates a displacement command for the first pump motor based on the signals from the displacement sensor, the signals from the first and second pressure sensors in the two chambers, and the displacement command input by the operator. Then, it generates a speed command for the dual-shaft extension motor based on the displacement of the first pump motor and the displacement command input by the operator, thereby controlling the output displacement of the hydraulic actuator and recovering excess load force to generate regenerative torque. When the regenerative torque is less than the torque required by the second pump motor, the regenerative torque is used to assist the dual-shaft extension motor in driving the second pump motor. When the regenerative torque is greater than the torque required by the second pump motor, part of the regenerative torque is used to drive the second pump motor, and the excess part is used to drive the dual-shaft extension motor to generate electricity. The electrical energy is then stored in the power supply unit through the drive and power generation unit. Simultaneously, the operating condition identification and control unit generates a displacement command for the second pump motor based on the signals from the first and second pressure sensors and the pressure command input by the operator, thereby controlling the oil inlet pressure of the hydraulic actuator and ensuring the operating rigidity of the system.

2. The control method for a pump-controlled electro-hydraulic system based on a dual-shaft extension motor according to claim 1, characterized in that, Both the first pump motor and the second pump motor are selected from four-quadrant pumps or two-quadrant pumps.

3. The control method for a pump-controlled electro-hydraulic system based on a dual-shaft extension motor according to claim 1, characterized in that, When the system is working, the drive and power generation unit is also connected to an external power supply unit, which is an energy storage element or a power grid.

4. The control method for a pump-controlled electro-hydraulic system based on a dual-shaft extension motor according to claim 1, characterized in that, The working condition identification and control unit has a built-in working condition identification algorithm and a control algorithm. The working condition identification algorithm is used to determine the working condition of the hydraulic actuator based on the received sensor signals and control command signals. The control algorithm is used to generate displacement control commands for the first pump motor and the second pump motor, as well as speed commands for the dual-shaft extension motor, based on the received working condition signals, sensor signals and control commands, so as to control the output displacement of the hydraulic actuator.

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