Hydraulic actuator based on servo motor plunger pump

Abstract

The invention relates to a hydraulic actuator based on a servo motor plunger pump, and belongs to the technical field of servo mechanisms. Comprising a servo motor pump, a first oil supplementing one-way valve, a second oil supplementing one-way valve, a first safety valve, a second safety valve, a manual bypass valve, an electromagnetic bypass valve, a damper, a balance valve, a filter, a pressurization oil tank and a hydraulic cylinder. An integrated servo motor plunger pump is adopted, a servo motor and the plunger pump are coaxially connected in a shell-sharing mode, and no coupler exists. The plunger pump is small in leakage and high in efficiency, high-precision speed control of the actuator is achieved, and the problems of miniaturization and reliability are solved through the integrated design; the integrated design of an integrated driving control module, a driving module, a control module, a power supply module and the like is adopted; bidirectional active control of the actuator is achieved, and the actuator can be actively and controllably driven to retract or stretch out through the servo motor pump under any working condition. The control precision of the actuator is improved, and the defect of one-way controllable output of an existing actuator is overcome.

Description

Technical Field

[0001] The invention belongs to the technical field of servo mechanisms and relates to a hydraulic actuator based on a servo motor plunger pump. Background Art

[0002] The hydraulic actuator is a driving device for the deformation of the active reflector surface of the FAST telescope and is an important component of the FAST telescope. The existing technical solutions mainly use a stepper motor or a servo motor with a bidirectional gear pump as the power source; the motor and the pump are connected through a separate coupling; a separate driver module and a controller module are used, and the two are connected through an external cable. The actuator actively retracts when the motor pump rotates forward; the hydraulically controlled one-way valve or the balancing valve is opened when the motor pump rotates reversely, and the actuator is passively extended under the action of an external tensile load; the actuator is extended by differential means under the action of the electromagnetic valve when the motor pump rotates forward.

[0003] 1) The patent "CN103629171 B" of Tianjin Yourunus Hydraulic Machinery Co., Ltd. discloses a hydraulic actuator with a speed control device. The actuator uses a stepper motor with a bidirectional gear pump as a power source. The actuator has a hydraulically controlled one-way valve in the rod chamber oil circuit, and a flow control valve is set in front of the solenoid valve. The actuator has active retraction, passive extension and differential extension functions, and the differential extension speed can be controlled by a flow valve.

[0004] 2) The patent "CN107489665A" of the National Astronomical Observatory of the Chinese Academy of Sciences discloses a direct-drive volume control electro-hydraulic servo single-acting hydraulic actuator, which uses a stepper motor and a bidirectional gear pump as the power source, and the actuator has a rod chamber oil circuit with a hydraulically controlled one-way valve. The motor pump outputs pressure oil in the forward rotation to directly drive the piston rod to actively retract; the motor pump reverses and outputs pressure oil to open the hydraulically controlled one-way valve, and the piston rod can be passively extended under the action of an external tensile load, and the piston rod extension speed is controlled by controlling the motor pump speed; when there is no external tensile load, the motor pump outputs pressure oil in the forward rotation, and the piston rod differential extension is completed by controlling the solenoid valve switch.

[0005] 3) Patent CN112901572A of Jiangsu Hengli Hydraulic Technology Co., Ltd. and National Astronomical Observatory of the Chinese Academy of Sciences discloses a pump-controlled double-acting hydraulic actuator, which uses a servo motor and a gear pump as a power source. The actuator has a rod chamber with a balancing valve. The motor pump rotates forward to drive the actuator to actively retract. The motor pump reverses to output pressure oil to open the balancing valve, and the piston rod can be passively extended under the action of an external tensile load. The piston rod extension speed is controlled by controlling the motor pump speed. When there is no external tensile load, the motor pump rotates forward to output pressure oil, and the differential extension of the piston rod is completed by controlling the solenoid valve switch.

[0006] 4) Wang Tiantian from Yanshan University proposed a new scheme of direct-drive volumetric controlled hydraulic actuator in his master's thesis "Research on Hydraulic Actuator of Active Reflector Surface of FAST Project". This scheme uses AC asynchronous motor variable frequency speed regulation to drive bidirectional gear pump to realize bidirectional variable speed movement of the actuator. The variable frequency motor pump works forward and reverse to drive the actuator to retract or extend.

[0007] 5) Wang Liugen from Yanshan University proposed a new electro-hydraulic actuator for FAST active reflector adjustment system in his master's thesis "Development and Performance Analysis of New Hydraulic Actuator for FAST". The solution adopts a servo motor + bidirectional piston pump to control the asymmetric cylinder. The servo motor pump works forward and reverse to drive the actuator to retract or extend.

[0008] Problems:

[0009] 1) In the prior art, the hydraulic pump and the motor are connected through an independent coupling, which is easy to wear, has poor reliability and low transmission efficiency;

[0010] 2) In the prior art, the driver module and the controller module are separate and independent structures, and the two modules are connected by an external cable, which makes the wiring complicated and has poor reliability;

[0011] 3) In the existing patented technology, the actuator can only be passively extended under the action of an external tensile load. When there is no external tensile load, the actuator can only achieve differential extension by switching the oil circuit through the hydraulic valve. The control accuracy and controllability of the actuator extension process are poor, and the complexity of the hydraulic system is increased. Summary of the invention

[0012] The technical problem solved by the present invention is: to overcome the deficiencies of the prior art and propose a hydraulic actuator based on a servo motor plunger pump, thereby solving the problems in the prior art of servo motor pump coupling wear, low integration of the drive control module, and the inability of the actuator to actively extend.

[0013] The solution of the present invention is:

[0014] A hydraulic actuator based on a servo motor plunger pump, comprising a servo motor pump, a first oil replenishment check valve, a second oil replenishment check valve, a first safety valve, a second safety valve, a manual bypass valve, an electromagnetic bypass valve, a damper, a balancing valve, a filter, a booster tank, and a hydraulic cylinder;

[0015] Among them, the servo motor plunger pump oil port A is connected to the balance valve oil inlet; the balance valve oil outlet is connected to the hydraulic cylinder rod cavity A port; the balance valve control oil port is connected to the motor pump oil port B; the oil ports at both ends of the filter are respectively connected to the hydraulic cylinder rodless cavity B port and the servo motor plunger pump oil port B;

[0016] The oil outlet of the first oil replenishment check valve is connected to the oil port A of the motor pump; the oil inlet of the first oil replenishment check valve is connected to the booster tank; the control oil port of the first oil replenishment check valve is connected to the oil port B of the motor pump; the outlet of the second oil replenishment check valve is connected to the oil port B of the motor pump; the oil inlet of the second oil replenishment check valve is connected to the booster tank; the control oil port of the second oil replenishment check valve is connected to the oil port A of the motor pump;

[0017] The first safety valve inlet is connected to the hydraulic cylinder rod chamber A port; the first safety valve outlet is connected to the booster tank; the second safety valve inlet is connected to the hydraulic cylinder rodless chamber B port; the second safety valve outlet is connected to the booster tank;

[0018] The three oil ports of the manual bypass valve are respectively connected to the rod chamber A port, rodless chamber B port and booster tank of the hydraulic cylinder;

[0019] The oil inlet of the electromagnetic bypass valve is connected to the A port of the rod chamber of the hydraulic cylinder; the oil outlet of the electromagnetic bypass valve is connected to the B port of the rodless chamber of the hydraulic cylinder through the damper.

[0020] In the above-mentioned hydraulic actuator based on a servo motor plunger pump, the working states of the hydraulic actuator include an active retracted state, an active extended state, a position holding state, an electrically controlled follow-up extended state and a manually followed extended state.

[0021] In the above-mentioned hydraulic actuator based on a servo motor plunger pump, the working process of the active retraction state is:

[0022] The servo motor pump receives the command from the upper computer and rotates forward; the servo motor pump oil port A outputs pressure oil into the rod chamber of the hydraulic cylinder through the balance valve; at this time, the oil replenishment check valve is closed, and the oil replenishment check valve opens in the reverse direction under the action of the control oil pressure; the servo motor pump oil port B is connected to the booster tank; the oil in the rodless chamber of the hydraulic cylinder flows out through the filter; a part of the oil enters the servo motor pump oil port B; the rest of the oil flows back to the booster tank through the oil replenishment check valve; the hydraulic cylinder actively retracts, and the actuator forms a retraction action circulation oil circuit.

[0023] In the above-mentioned hydraulic actuator based on the servo motor plunger pump, in the active retracted state, the safety valve, the safety valve, the manual bypass valve, and the electromagnetic bypass valve are all in the closed state.

[0024] In the above-mentioned hydraulic actuator based on a servo motor plunger pump, the working process of the active extension state is:

[0025] The servo motor pump receives the command from the upper computer and rotates in the opposite direction; the output pressure oil from the servo motor pump oil port B enters the rodless chamber of the hydraulic cylinder through the filter; at this time, the oil replenishment check valve is closed; the oil replenishment check valve opens in the opposite direction under the action of the control oil pressure; the motor pump oil port A is connected to the booster tank; the balance valve opens in the opposite direction to a certain degree under the action of the control oil pressure, and the oil in the rod chamber of the hydraulic cylinder flows back to the motor pump oil port A through the balance valve; at the same time, a part of the oil in the booster tank enters the motor pump oil port A through the oil replenishment check valve, the oil replenishment is completed, the hydraulic cylinder actively extends, and the actuator forms a circulating oil circuit for the extension action.

[0026] In the above-mentioned hydraulic actuator based on a servo motor plunger pump, in the active extension state, the safety valve, the safety valve, the manual bypass valve, and the electromagnetic bypass valve are all in a closed state.

[0027] In the above-mentioned hydraulic actuator based on a servo motor plunger pump, in the position holding state, the servo motor pump stops working; the manual bypass valve and the electromagnetic bypass valve are both in a closed state; the balance valve is in a reverse closed state; the hydraulic cylinder rod chamber oil circuit and the motor pump oil port A are disconnected; the oil in the hydraulic cylinder rod chamber cannot flow, and the hydraulic cylinder remains in the current position.

[0028] In the above-mentioned hydraulic actuator based on a servo motor plunger pump, the working process of the electrically controlled follower in the extended state is as follows:

[0029] The servo motor pump stops working; the manual bypass valve is in the closed state; the balancing valve is in the reverse closed state; the hydraulic cylinder rod chamber oil circuit and the motor pump oil port A are disconnected; the upper computer sends a follow-up command, the electromagnetic bypass valve is energized and opened, and the hydraulic cylinder rod chamber and rodless chamber are connected through the electromagnetic bypass valve and damping to achieve oil circuit communication; the hydraulic cylinder is extended by follow-up under the action of external tensile load.

[0030] In the above-mentioned hydraulic actuator based on a servo motor plunger pump, the working process in the manual follow-up extension state is:

[0031] The servo motor pump stops working; the electromagnetic bypass valve is in the closed state; the balance valve is in the reverse closed state; the hydraulic cylinder rod chamber oil circuit and the motor pump oil port A are disconnected; the manual bypass valve is opened; the hydraulic cylinder rod chamber and rodless chamber are connected to the booster tank through the manual bypass valve; the hydraulic cylinder is extended with follow-up under the action of external tensile load.

[0032] In the above-mentioned hydraulic actuator based on a servo motor plunger pump, the servo motor pump adopts a coaxial and common shell connection form of the servo motor and the plunger pump without a coupling.

[0033] The beneficial effects of the present invention compared with the prior art are:

[0034] (1) The present invention adopts an integrated servo motor pump module, and the servo motor and the plunger pump are coaxially connected to the same shell without a separate coupling. Compared with the existing solution, there is no coupling wear problem and the reliability is higher; the plunger pump has high volumetric efficiency and the speed control accuracy of the actuator is higher;

[0035] (2) The present invention adopts an integrated drive control module, and the drive module, control module, power module and the like are integrated in design; there is no external cable connection between the modules, the reliability is high, the structure is compact, and the use and maintenance are convenient;

[0036] (3) The present invention uses a servo motor plunger pump to realize bidirectional active control of the actuator. The actuator can be directly driven to retract or extend by the servo motor pump under any working condition, thereby improving controllability. On the basis of solving the extension control accuracy, the retraction control accuracy is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the hydraulic actuator system of the present invention;

[0038] Figure 2 It is a schematic diagram of the structure of the hydraulic actuator of the present invention. DETAILED DESCRIPTION

[0039] The present invention will be further described below in conjunction with the embodiments.

[0040] The present invention provides a hydraulic actuator based on a servo motor plunger pump, which solves the problems in the prior art of servo motor pump coupling wear, low integration of a drive control module, and failure of the actuator to actively extend.

[0041] Hydraulic actuators based on servomotor piston pumps, such as Figure 1 As shown, it specifically includes a servo motor pump 1, a first oil replenishment check valve 21, a second oil replenishment check valve 22, a first safety valve 31, a second safety valve 32, a manual bypass valve 4, an electromagnetic bypass valve 5, a damper 6, a balance valve 7, a filter 8, a booster oil tank 9, and a hydraulic cylinder 10. Among them, the oil port A of the servo motor plunger pump 1 is connected to the oil inlet of the balance valve 7; the oil outlet of the balance valve 7 is connected to the rod cavity A port of the hydraulic cylinder 10; the control oil port of the balance valve 7 is connected to the oil port B of the motor pump 1; the oil ports at both ends of the filter 8 are respectively connected to the rodless cavity B port of the hydraulic cylinder 10 and the oil port B of the servo motor plunger pump 1.

[0042] The oil outlet of the first oil replenishment check valve 21 is connected to the oil port A of the motor pump 1; the oil inlet of the first oil replenishment check valve 21 is connected to the boost oil tank 9; the control oil port of the first oil replenishment check valve 21 is connected to the oil port B of the motor pump 1; the outlet of the second oil replenishment check valve 22 is connected to the oil port B of the motor pump 1; the oil inlet of the second oil replenishment check valve 22 is connected to the boost oil tank 9; the control oil port of the second oil replenishment check valve 22 is connected to the oil port A of the motor pump 1. The inlet of the first safety valve 31 is connected to the rod chamber A port of the hydraulic cylinder 10; the outlet of the first safety valve 31 is connected to the boost oil tank 9; the inlet of the second safety valve 32 is connected to the rodless chamber B port of the hydraulic cylinder 10; the outlet of the second safety valve 32 is connected to the boost oil tank 9. The three oil ports of the manual bypass valve 4 are respectively connected to the rod chamber A port, the rodless chamber B port and the boost oil tank 9 of the hydraulic cylinder 10. The oil inlet of the electromagnetic bypass valve 5 is connected to the rod chamber A port of the hydraulic cylinder 10; the oil outlet of the electromagnetic bypass valve 5 is connected to the rodless chamber B port of the hydraulic cylinder 10 through the damper 6.

[0043] The working states of the hydraulic actuator include active retraction state, active extension state, position holding state, electric control follow-up extension state and manual follow-up extension state.

[0044] The servo motor pump 1 adopts the coaxial and common shell connection form of the servo motor and the plunger pump without a coupling.

[0045] The working process of the active retraction state is:

[0046] The servo motor pump 1 receives the command from the upper computer and rotates forward; the output pressure oil from the oil port A of the servo motor pump 1 enters the rod chamber of the hydraulic cylinder 10 through the balance valve 7; at this time, the oil replenishment check valve 21 is closed, and the oil replenishment check valve 22 opens in the opposite direction under the control oil pressure; the oil port B of the servo motor pump 1 is connected to the booster tank 9; the oil in the rodless chamber of the hydraulic cylinder 10 flows out through the filter 8; a part of the oil enters the oil port B of the servo motor pump 1; the rest of the oil flows back to the booster tank 9 through the oil replenishment check valve 22; the hydraulic cylinder 10 actively retracts, and the actuator forms a retracting action circulation oil circuit. In the active retracted state, the safety valve 31, the safety valve 32, the manual bypass valve 4, and the electromagnetic bypass valve 5 are all in the closed state.

[0047] The working process of active extension state is:

[0048] The servo motor pump 1 receives the command from the upper computer and rotates in the reverse direction; the output pressure oil from the oil port B of the servo motor pump 1 enters the rodless chamber of the hydraulic cylinder 10 through the filter 8; at this time, the oil replenishment check valve 22 is closed; the oil replenishment check valve 21 is opened in the reverse direction under the control oil pressure; the motor pump 1 oil port A is connected to the booster tank 9; the balance valve 7 is opened in the reverse direction to a certain degree under the control oil pressure, and the oil in the rod chamber of the hydraulic cylinder 10 flows back to the motor pump 1 oil port A through the balance valve 7; at the same time, part of the oil in the booster tank 9 enters the motor pump 1 oil port A through the oil replenishment check valve 21, completing the oil replenishment, the hydraulic cylinder 10 actively extends, and the actuator forms an extension action circulation oil circuit. In the active extension state, the safety valve 31, the safety valve 32, the manual bypass valve 4, and the electromagnetic bypass valve 5 are all in the closed state.

[0049] In the position holding state, the servo motor pump 1 stops working; the manual bypass valve 4 and the electromagnetic bypass valve 5 are both in the closed state; the balance valve 7 is in the reverse closed state; the rod chamber oil circuit of the hydraulic cylinder 10 and the oil port A of the motor pump 1 are disconnected; the oil in the rod chamber of the hydraulic cylinder 10 cannot flow, and the hydraulic cylinder remains in the current position.

[0050] The working process of the electric control follow-up extension state is:

[0051] The servo motor pump 1 stops working; the manual bypass valve 4 is in the closed state; the balance valve 7 is in the reverse closed state; the rod chamber oil circuit of the hydraulic cylinder 10 and the oil port A of the motor pump 1 are disconnected; the upper computer sends a follow-up command, the electromagnetic bypass valve 5 is energized and opened, and the rod chamber and the rodless chamber of the hydraulic cylinder 10 are connected in the oil circuit through the electromagnetic bypass valve 5 and the damper 6; the hydraulic cylinder 10 is extended by follow-up under the action of the external tensile load.

[0052] The working process in the manual follow-up extension state is:

[0053] The servo motor pump 1 stops working; the electromagnetic bypass valve 5 is in a closed state; the balance valve 7 is in a reverse closed state; the rod chamber oil circuit of the hydraulic cylinder 10 and the oil port A of the motor pump 1 are disconnected; the manual bypass valve 4 is opened; the rod chamber and the rodless chamber of the hydraulic cylinder 10 are connected to the booster tank 9 through the manual bypass valve 4; the hydraulic cylinder 10 is extended servo-actively under the action of an external tensile load.

[0054] like Figure 2As shown, the hydraulic cylinder is a single-rod asymmetric structure with an integrated magnetostrictive displacement sensor; the servo motor is equipped with an axial piston pump as a power source; the motor pump outlet is bypassed with an oil replenishment check valve, which is used for replenishing the servo motor pump and discharging the excess oil in the rodless chamber back to the oil tank when the asymmetric hydraulic cylinder is retracted; a balance valve is set in the rod chamber oil circuit of the hydraulic cylinder to maintain the position of the hydraulic cylinder; high and low pressure safety valves are set in the two-chamber oil circuit of the hydraulic cylinder to protect the actuator and facilitate debugging; a filter is set in the rodless chamber oil circuit of the hydraulic cylinder to maintain the cleanliness of the medium and maintain the long-term operation of the device; solenoid valves and damping holes are set in the two chambers of the hydraulic cylinder to realize the electric control follow-up function of the actuator, and the follow-up movement speed is limited by the damper; a manual bypass valve is set between the two chambers of the hydraulic cylinder to realize the manual follow-up function of the actuator.

[0055] The present invention adopts an integrated servo motor pump module, and the servo motor and the plunger pump are coaxially connected with the same shell without a separate coupling. Compared with the existing solution, there is no coupling wear problem and the reliability is higher; the plunger pump has high volumetric efficiency and the speed control accuracy of the actuator is higher.

[0056] The present invention adopts an integrated drive control module, drive module, control module, power module, etc. There is no external cable connection between modules, high reliability, compact structure, and easy use and maintenance.

[0057] The present invention uses a servo motor plunger pump to realize bidirectional active control of the actuator, and the actuator can be directly driven to retract or extend by the servo motor pump under any working condition, thereby improving controllability. On the basis of solving the extension control accuracy, the retraction control accuracy is improved.

[0058] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A hydraulic actuator based on a servo motor plunger pump, characterized in that: It comprises a servo motor pump (1), a first oil replenishment check valve (21), a second oil replenishment check valve (22), a first safety valve (31), a second safety valve (32), a manual bypass valve (4), an electromagnetic bypass valve (5), a damper (6), a balancing valve (7), a filter (8), a booster oil tank (9), and a hydraulic cylinder (10); The oil port A of the servo motor plunger pump (1) is connected to the oil inlet of the balance valve (7); the oil outlet of the balance valve (7) is connected to the rod chamber A port of the hydraulic cylinder (10); the control oil port of the balance valve (7) is connected to the oil port B of the motor pump (1); and the oil ports at both ends of the filter (8) are respectively connected to the rodless chamber B port of the hydraulic cylinder (10) and the oil port B of the servo motor plunger pump (1); The oil outlet of the first oil replenishment check valve (21) is connected to the oil port A of the motor pump (1); the oil inlet of the first oil replenishment check valve (21) is connected to the boost oil tank (9); the control oil port of the first oil replenishment check valve (21) is connected to the oil port B of the motor pump (1); the outlet of the second oil replenishment check valve (22) is connected to the oil port B of the motor pump (1); The oil inlet of the second oil replenishment check valve (22) is connected to the boost oil tank (9); the control oil port of the second oil replenishment check valve (22) is connected to the oil port A of the motor pump (1); The inlet of the first safety valve (31) is connected to the rod chamber A port of the hydraulic cylinder (10); the outlet of the first safety valve (31) is connected to the booster oil tank (9); the inlet of the second safety valve (32) is connected to the rodless chamber B port of the hydraulic cylinder (10); the outlet of the second safety valve (32) is connected to the booster oil tank (9); The three oil ports of the manual bypass valve (4) are respectively connected to the rod chamber A port, the rodless chamber B port and the booster oil tank (9) of the hydraulic cylinder (10); The oil inlet of the electromagnetic bypass valve (5) is connected to the rod chamber A port of the hydraulic cylinder (10); the oil outlet of the electromagnetic bypass valve (5) is connected to the rodless chamber B port of the hydraulic cylinder (10) via the damper (6).

2. A hydraulic actuator based on a servo motor plunger pump according to claim 1, characterized in that: The working states of the hydraulic actuator include active retraction state, active extension state, position holding state, electric control follow-up extension state and manual follow-up extension state.

3. A hydraulic actuator based on a servo motor plunger pump according to claim 2, characterized in that: The working process of the active retraction state is as follows: The servo motor pump (1) receives the command from the upper computer and rotates forward; the pressure oil output from the oil port A of the servo motor pump (1) enters the rod chamber of the hydraulic cylinder (10) through the balance valve (7); at this time, the oil replenishment check valve (21) is closed, and the oil replenishment check valve (22) opens in the reverse direction under the action of the control oil pressure; the oil port B of the servo motor pump (1) is connected to the booster tank (9); the oil in the rod chamber of the hydraulic cylinder (10) flows out through the filter (8); a part of the oil enters the oil port B of the servo motor pump (1); the remaining oil flows back to the booster tank (9) through the oil replenishment check valve (22); the hydraulic cylinder (10) actively retracts, and the actuator forms a retraction action circulation oil circuit.

4. A hydraulic actuator based on a servo motor plunger pump according to claim 3, characterized in that: In the active retracted state, the safety valve (31), the safety valve (32), the manual bypass valve (4) and the electromagnetic bypass valve (5) are all in a closed state.

5. The hydraulic actuator based on a servo motor plunger pump according to claim 2, characterized in that: The working process of the active extension state is as follows: The servo motor pump (1) receives the command from the upper computer and rotates in the reverse direction; the pressure oil output from the oil port B of the servo motor pump (1) enters the rodless chamber of the hydraulic cylinder (10) through the filter (8); at this time, the oil replenishment check valve (22) is closed; the oil replenishment check valve (21) is opened in the reverse direction under the action of the control oil pressure; the motor pump (1) oil port A is connected to the booster tank (9); the balance valve (7) is opened in the reverse direction to a certain degree under the action of the control oil pressure, and the oil in the rod chamber of the hydraulic cylinder (10) flows back to the motor pump (1) oil port A through the balance valve (7); at the same time, a part of the oil in the booster tank (9) enters the motor pump (1) oil port A through the oil replenishment check valve (21), completing the oil replenishment, the hydraulic cylinder (10) actively extends, and the actuator forms an extension action circulation oil circuit.

6. The hydraulic actuator based on a servo motor plunger pump according to claim 5, characterized in that: In the active extension state, the safety valve (31), the safety valve (32), the manual bypass valve (4) and the electromagnetic bypass valve (5) are all in a closed state.

7. The hydraulic actuator based on a servo motor plunger pump according to claim 2, characterized in that: In the position holding state, the servo motor pump (1) stops working; the manual bypass valve (4) and the electromagnetic bypass valve (5) are both in a closed state; the balance valve (7) is in a reverse closed state; the rod chamber oil circuit of the hydraulic cylinder (10) and the oil port A of the motor pump (1) are disconnected; the oil in the rod chamber of the hydraulic cylinder (10) cannot flow, and the hydraulic cylinder remains in the current position.

8. The hydraulic actuator based on a servo motor plunger pump according to claim 2, characterized in that: The working process of the electrically controlled follower in the extended state is as follows: The servo motor pump (1) stops working; the manual bypass valve (4) is in a closed state; the balance valve (7) is in a reverse closed state; the rod chamber oil circuit of the hydraulic cylinder (10) and the oil port A of the motor pump (1) are disconnected; the upper computer sends a follow-up instruction, the electromagnetic bypass valve (5) is energized and opened, and the rod chamber and the rodless chamber of the hydraulic cylinder (10) are connected in the oil circuit through the electromagnetic bypass valve (5) and the damper (6); the hydraulic cylinder (10) is extended in a follow-up manner under the action of an external tensile load.

9. The hydraulic actuator based on a servo motor plunger pump according to claim 2, characterized in that: The working process in the manual follow-up extended state is as follows: The servo motor pump (1) stops working; the electromagnetic bypass valve (5) is in a closed state; the balance valve (7) is in a reverse closed state; the rod chamber oil circuit of the hydraulic cylinder (10) and the oil port A of the motor pump (1) are disconnected; the manual bypass valve (4) is opened; the rod chamber and the rodless chamber of the hydraulic cylinder (10) are connected to the booster oil tank (9) through the manual bypass valve (4); the hydraulic cylinder (10) is extended servo-actively under the action of an external tensile load.

10. The hydraulic actuator based on a servo motor plunger pump according to claim 1, characterized in that: The servo motor pump (1) adopts a coaxial and common shell connection mode of the servo motor and the plunger pump, without a coupling.

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