Closed numerical control hydraulic pump and robot

Abstract

The invention provides a closed type numerical control hydraulic pump and a robot. The closed type numerical control hydraulic pump comprises a sub-pump body and at least one mother pump body, and the sub-pump body is connected with the mother pump body through a hose to form a closed type space hydraulic cavity; the mother pump body is driven by a servo motor to drive the son pump bodies to move synchronously. The oil pump comprises a closed single pump body and a double pump body, and under the condition that the oil amount is certain, a mother pump body drives a son pump body to continuously reciprocate; the mounting position of the sub-pump body is flexible and is not limited by the size of a space range; the device is easy to carry and can be remotely controlled to move; the output direction is free, the fixed-point staying position is accurate, energy consumption is small, and safety and reliability are achieved.

Description

Technical Field

[0001] The present application belongs to the technical field of CNC hydraulic pumps, and in particular, relates to a closed CNC hydraulic pump and a robot equipped with the CNC hydraulic pump. Background Art

[0002] At present, most traditional hydraulic pumps are large and single-pump open structures. They cannot be installed in narrow spaces and are not easy to carry. Because this single-pump open hydraulic pump is greatly affected by working conditions, once its position is fixed, its output direction is single, and it can only reciprocate in one direction along the direction of the pump body connection position, and cannot control robots or remote objects. In addition, conventional hydraulic pumps have power consumption losses when they stay at a fixed position and are subjected to force.

[0003] The maximum arm strength of humanoid robots on the market is currently 20 kg, which is not enough to lift a disabled human body. Therefore, the use of a closed CNC hydraulic pump based on the principle of specifications can enable a single arm to lift a 50 kg weight. The average weight of a person is less than 100 kg. In addition, due to the poor portability of existing hydraulic cylinders, it is impossible to flexibly control the robotic arm. In addition, existing humanoid robots do not have a spine design, which affects the range of the center of gravity adjustment of the humanoid robot. The closed CNC hydraulic pump can remotely control the micro hydraulic cylinder to adjust the spinal joints, thereby adjusting the posture of the humanoid robot and achieving anthropomorphic adjustment of the center of gravity. Summary of the invention

[0004] The present application provides a closed CNC hydraulic pump and robot, which solve the technical problems of the existing single-pump open-structure hydraulic pump having a single output direction, a large volume and an inability to work directly in a narrow space.

[0005] In order to solve at least one of the above technical problems, the technical solution adopted in this application is:

[0006] A closed CNC hydraulic pump comprises a sub-pump body and at least one main pump body, wherein the sub-pump body is connected to the main pump body via a hose to form a closed air-tight hydraulic chamber; the main pump body is driven by a servo motor to drive the sub-pump body to move synchronously.

[0007] Furthermore, the servo motor is directly connected to the mother pump body through a reducer; the number of the hoses is two; and the reducer is connected to the mother piston in the mother pump body through a ball screw.

[0008] Furthermore, the number of the mother pump bodies is one or two, and the number of the sub-pump body is one; the hydraulic chamber in each of the mother pump body and the sub-pump body is provided with a rodless chamber end and a rod chamber end.

[0009] Furthermore, when there is only one mother pump body, the servo motor is connected to the mother pump body through a reducer with a single output shaft; the diameter of the hydraulic cavity of the sub-pump body is the same as the diameter of the hydraulic cavity of the mother pump body.

[0010] Furthermore, one of the hoses is respectively connected to the rodless cavity ends of the hydraulic cavities in the sub-pump body and the main pump body; the other hose is respectively connected to the rod cavity ends of the hydraulic cavities in the sub-pump body and the main pump body.

[0011] Furthermore, when there are two mother pump bodies, they include one mother pump body with a short cylinder body and one mother pump body with a long cylinder body; the servo motor is respectively connected to the two mother pump bodies through a reducer with dual output shafts.

[0012] Furthermore, one of the hoses is respectively connected to the rodless chamber end of the hydraulic chamber in the sub-pump body and the rodless chamber end of the mother pump body with the short cylinder body; the other hose is respectively connected to the rod chamber end of the hydraulic chamber in the sub-pump body and the rodless chamber end of the mother pump body with the long cylinder body.

[0013] Furthermore, the diameter of the short cylinder is greater than the diameter of the long cylinder.

[0014] A robot is provided with a closed CNC hydraulic pump as described above on its arm, wherein the sub-pump body is constructed on the upper arm, the fixing seat at the tail of the sub-pump body is fixed on the side of the upper arm close to the scapula, and the suspension end is pivotally connected to the connecting shaft between the upper arm and the lower arm through a pin shaft.

[0015] Furthermore, the mother pump body and the sub-pump body are arranged on the same side of the big arm or are configured away from the big arm.

[0016] A closed CNC hydraulic pump designed by the present application includes a closed single pump body and a double pump body. Under the condition of a certain amount of oil, the mother pump body drives the sub-pump body to continuously reciprocate; the sub-pump body can be installed flexibly and is not limited by the size of the space range; it is easy to carry and its movement can be remotely controlled; not only is the output direction free, but the fixed-point stop position is accurate, the energy consumption is low, and it is safe and reliable. The present application also proposes a robot equipped with the closed CNC hydraulic pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a front view of a double-pump enclosed CNC hydraulic pump in the present application;

[0018] Figure 2 yes Figure 1 Middle AA section view;

[0019] Figure 3 is a top view of a double-pump enclosed CNC hydraulic pump in the present application;

[0020] Figure 4 It is a front view of a single-pump enclosed CNC hydraulic pump in the present application;

[0021] Figure 5 is a cross-sectional view of a single-pump enclosed CNC hydraulic pump in the present application;

[0022] Figure 6 This is an example diagram of a robot arm that uses a dual-pump enclosed CNC hydraulic pump control;

[0023] Figure 7 This is another example diagram of a robot arm controlled by a dual-pump enclosed CNC hydraulic pump.

[0024] In the figure:

[0025] 10. Sub-pump body 11. Sub-piston 12. Fixed seat

[0026] 13. Pin 20, mother pump body 21, mother piston

[0027] 22. Ball screw 23. Guide key 24. Short cylinder

[0028] 25, long cylinder 30, hose 40, servo motor

[0029] 50, reducer 60, big arm 70, small arm

[0030] 80. Shoulder bone A, rodless cavity end B, rod cavity end

[0031] C. Rodless cavity end D. Rod cavity end E. Rodless cavity end DETAILED DESCRIPTION

[0032] The present application is described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] This embodiment provides a closed type numerically controlled hydraulic pump, such as Figure 1-5 As shown, it includes a sub-pump body 10 and at least one mother pump body 20, and the sub-pump body 10 is connected to the mother pump body 20 through a hose 30 to form a closed air-insulated hydraulic cavity, wherein the amount of hydraulic oil in the hydraulic cavity of the sub-pump body 10 and the mother pump body 20 is a fixed value, and the mother pump body 20 is driven by a servo motor 40 to drive the sub-pump body 10 to move synchronously, thereby indirectly controlling the sub-pump body 20 to perform reciprocating motion in any direction set by itself through the mother pump body 20, which is not only portable but also can adjust the hose length based on actual working conditions, and adapt to the operation of the sub-pump body 10 controlled at any distance. This closed CNC hydraulic pump is not only not limited by the size of the space range, but also can be remotely controlled, has a free output direction, and has a precise fixed-point stop position, low energy consumption, and is safe and reliable.

[0034] In the present application, the servo motor 40 is directly connected to the mother pump body 20 through the reducer 50, and the reducer 50 is connected to the mother piston 21 in the mother pump body 20 through the ball screw 22. The servo motor 40 drives the reducer 50 to make the ball screw 22 drive the mother piston 21 to push the hydraulic oil in the mother pump body 20, and the hydraulic oil is ejected under pressure and enters the cylinder in the sub-pump body 10 through the hose 30, thereby pushing the sub-piston 11 in the sub-pump body 10 to move.

[0035] In the present application, the number of the mother pump body 20 can be one, such as Figure 4-5 ; It can also be two, such as Figure 1-3 Regardless of the number of mother pump bodies 20, there is only one sub-pump body 10, and there are only two hoses 30, and their lengths can be determined according to actual conditions. The hydraulic chamber in each mother pump body 20 and sub-pump body 10, that is, in the hydraulic cylinder, is provided with a rodless chamber end and a rod chamber end; the hose 30 is respectively connected to the rodless chamber end / rod chamber end in the hydraulic chamber of the sub-pump body 10 and the rodless chamber end / rod chamber end in the hydraulic chamber of the mother pump body 20.

[0036] like Figure 1-3 As shown, when there are two mother pump bodies 20, they include a mother pump body 20 with a short cylinder body 24 and a mother pump body 20 with a long cylinder body 25, wherein the diameter of the short cylinder body 24 is greater than the diameter of the long cylinder body 25, and the volume of the hydraulic chamber in the short cylinder body 24 is greater than the volume of the hydraulic chamber in the long cylinder body 25, and thus the amount of oil stored in the short cylinder body 25 is greater than the amount of oil stored in the long cylinder body 25. This is because the rodless chamber end A of the hydraulic chamber in the sub-pump body 10 is connected to the rodless chamber end C in the short cylinder body 24 through the hose 30; the rod chamber end B of the hydraulic chamber in the sub-pump body 10 is connected to the rodless chamber end E of the long cylinder body 25. For the sub-pump body 10, although the internal diameter of its hydraulic chamber is the same, the chamber area at the rodless chamber end A is greater than the chamber area at the rod chamber end B, that is, the amount of oil required at the rodless chamber end A in the sub-pump body 10 is greater than the amount of oil at the rod chamber end B.

[0037] like Figure 3 As shown, the servo motor 40 is connected to the two mother pump bodies 20 through a dual-output shaft reducer 50, wherein the short cylinder body 24 is connected to the positive output shaft of the reducer 50 through a ball screw 22, and the long cylinder body 24 is connected to the reverse output shaft of the reducer 50 through a ball screw 22. Based on different fixing scenarios, guide keys 23 can be set outside the pump bodies of the two mother pumps 20 for easy installation and fixing.

[0038] from Figure 3It can be seen that the servo motor 40 is connected to the reducer 50, and the reducer 50 is connected to the ball screw 22. What moves on the ball screw 22 is the nut, which is the female piston 21. The servo motor 40 can preset its output torque in advance through the PLC controller, and the motor encoder set on it can also record the rotation angle and number of rotations of the servo motor in real time, and it can determine the rotation position of the ball screw 22 without zero reset.

[0039] At the same time, after the preset parameters of the servo motor 50 are input in advance on the PLC controller, the servo motor 50 can adjust the output torque in real time, thereby ensuring that the thrust of the female piston 21 driven by the ball screw 22 matches the system load. In addition, the servo motor 40 has a self-locking and holding function, and can also control the ball screw position to automatically lock when the power is off to prevent the hydraulic cylinder from retreating due to gravity.

[0040] Furthermore, the linear motion of the ball screw 22 is directly converted into the change of the volume of the pump chamber, so that it can realize the precise displacement transmission of the hydraulic oil by driving the mother piston 21 to move. At the same time, based on the incompressibility of the hydraulic oil, the linear transmission of displacement → pressure → actuator thrust can be ensured. Moreover, through the reverse motion of the two ball screws, the double pump bodies can be rotated in different directions to compensate, so as to eliminate the risk of hydraulic cylinder shaking caused by discontinuous hydraulic oil flow.

[0041] In this dual-pump closed CNC hydraulic pump, the rod-side chamber volume and the rodless side chamber volume in the sub-pump body 10 are respectively interconnected with the absolutely closed chamber volumes in the two main pump bodies 20, and the servo motor 40 drives the reducer 50 with dual output shafts in opposite directions to rotate, and the reducer 50 then drives the two ball screws to rotate in opposite directions, and at the same time makes the two nuts serving as the main pistons 21 and adapted to the ball screws 22 move in the opposite direction, so that the pressurized hydraulic oil in the chambers of the two main pump bodies 20 is in a state of simultaneous discharge and recovery, so as to drive the sub-pump body 10 connected to the two main pump bodies 20 to work.

[0042] like Figure 3As shown, after receiving the command from the controller, the servo motor 40 rotates forward according to the preset output torque, and then drives the ball screw 22 in the short cylinder 24 to rotate through the reducer 50, while the long cylinder 25 does not move. The reducer 50 drives the female piston 21 in the short cylinder 24 to push and move from the rod cavity end B to the rodless cavity end A, that is, to the tail of the cylinder in the short cylinder 24. When the female piston 22 in the short cylinder 24 moves to the rodless cavity end A, the female piston 22 pushes the hydraulic oil in the cavity where the rodless cavity end A of the short cylinder 24 is located to be discharged from the rodless cavity end A in the short cylinder 24 to the rodless cavity end C in the cylinder of the sub-pump body 10 through the hose 30. Under the action of the pressurized oil, the sub-piston 11 in the sub-pump body 10 moves from the rodless chamber end C to the rod chamber end B in the cylinder body of the sub-pump body 10, and then the hydraulic oil in the chamber where the rod chamber end D of the sub-pump body 10 is located is pushed by the sub-piston 11, and is discharged from the hydraulic chamber where the rod chamber end D of the sub-pump body 10 is located into the hydraulic chamber where the rodless chamber end E in the long cylinder body 25 is located through another hose 30, thereby completing the propulsion operation of the sub-piston 11.

[0043] When the sub-piston 11 in the sub-pump body 10 needs to be controlled to retract, after the servo motor 30 receives the retraction command from the controller, the servo motor 30 starts to rotate in the opposite direction and rotates according to the preset output torque, and then drives the ball screw 22 to rotate through the reducer 50 to drive the female piston 21 in the long cylinder body 25 to retract and move toward the rodless cavity end E, that is, to move toward the side of the long cylinder body 25 close to the tail of the cylinder body, at this time, the short cylinder body 24 does not move. When the female piston 22 in the long cylinder body 25 moves toward the rodless cavity end E, the female piston 22 pushes the hydraulic oil in the long cylinder body 25 to be discharged from the rodless cavity end E of the long cylinder body 25 through the hose 30 into the cavity where the rod cavity end D in the cylinder body of the sub-pump body 10 is located. Under the action of the pressurized oil, the sub-piston 11 in the sub-pump body 10 moves from the rod cavity end D to its rodless cavity end C, and then the sub-piston 11 can push the hydraulic oil in the cavity where the rodless cavity end C is located to be discharged from the rodless cavity end C in the sub-pump body 10 into the cavity at the rodless cavity end A in the short cylinder body 24 through the hose 30, thereby completing the retraction operation of the sub-piston 11.

[0044] like Figure 4-5 As shown, when there is only one mother pump body 20, the servo motor 40 is connected to the mother pump body 20 through a single output shaft reducer 50; at the same time, two hoses 30 are respectively connected to the same end sides of the sub-pump body 10 and the mother pump body 20. Specifically, one of the hoses 30 is respectively connected to the rodless cavity end of the hydraulic cavity in the sub-pump body 10 and the mother pump body 20, that is, the rodless cavity end in the sub-pump body 10 and the rodless cavity end in the mother pump body 20 are respectively connected; the other hose 30 is respectively connected to the rod cavity end of the hydraulic cavity in the sub-pump body 10 and the mother pump body 20, that is, the rod cavity end in the sub-pump body 10 and the rod cavity end in the mother pump body 20 are respectively connected.

[0045] like Figure 5 As shown, the servo motor 40 is electrically connected to an external PCL controller (illustration omitted). After receiving the command from the controller, it starts to rotate in the forward direction and rotates according to the preset output torque, and then drives the ball screw 22 to rotate through the reducer 50 to drive the mother piston 21 in the mother pump body 20 to push and move toward the rodless cavity end A, that is, to move toward the tail of the cylinder body in the mother pump body 20. When the mother piston 22 moves from the rod cavity end B to the rodless cavity end A, the mother piston 22 pushes the hydraulic oil in the cavity where the rodless cavity end A in the mother pump body 20 is located to be discharged from the rodless cavity end A to the rodless cavity end C in the cylinder body of the sub-pump body 10 through the hose 30. Under the action of the pressurized oil, the sub-piston 11 in the sub-pump body 10 moves from the rodless chamber end C to the rod chamber end D in the cylinder body of the sub-pump body 10, and then the hydraulic oil in the cylinder body of the sub-pump body 10 is pushed by the sub-piston 11, and is discharged from the rod chamber end D in the hydraulic chamber of the sub-pump body 10 to the rod chamber end B in the hydraulic chamber of the mother pump body 20 through another hose 30, thereby completing the propulsion operation of the sub-piston 11.

[0046] When it is necessary to control the sub-piston 11 in the sub-pump body 10 to retract, after the servo motor 30 receives the retraction command from the controller, the servo motor 30 starts to rotate in the opposite direction and rotates according to the preset output torque, and then drives the ball screw 22 to rotate through the reducer 50 to drive the mother piston 21 in the mother pump body 20 to retract toward the rod chamber end B, that is, to move toward the side of the mother pump body 20 away from the tail of the cylinder. When the mother piston 22 moves toward the rod chamber end B, the mother piston 22 pushes the hydraulic oil in the cylinder of the mother pump body 20 to be discharged from the rod chamber end B in the hydraulic chamber of the mother pump body 20 to the rod chamber end D in the cylinder of the sub-pump body 10 through the hose 30 close to the reducer 50. Under the action of the pressurized oil, the sub-piston 11 in the sub-pump body 10 gradually moves from the rod chamber end D to the rodless chamber end C in its cylinder body, and then the hydraulic oil in the cylinder body of the sub-pump body 10 is pushed by the sub-piston 11, and is discharged from the rodless chamber end C in the hydraulic chamber of the sub-pump body 10 to the rodless chamber end A in the hydraulic chamber of the mother pump body 20 through the hose 30 away from the side of the reducer 50, thereby completing the retraction operation of the sub-piston 11.

[0047] In this embodiment, the cylinder diameter of the sub-pump body 10 is the same as that of the mother pump body 20, and the diameter of the sub-piston 11 is the same as that of the mother piston 21. Based on the incompressibility of the hydraulic oil, the quantitative hydraulic oil is continuously circulated in and out of the hydraulic cavity that is interconnected between the sub-pump body 10 and the mother pump body 20, so that the movement of the sub-piston 11 and the mother piston 21 is synchronized. When the mother piston 21 advances a certain distance in the cylinder of the mother pump body 20, it advances in the cylinder of the sub-pump body 10 at an equal distance relative to the sub-piston 11. Correspondingly, when the mother piston 21 retreats a certain distance in the cylinder of the mother pump body 20, the sub-piston 11 retreats a certain distance in the cylinder of the sub-pump body 10. At the same time, the servo motor has a self-locking function, so that the static state of the mount at any position can be effectively controlled, so that the sub-piston 21 can be accurately positioned to achieve fixed-point stop.

[0048] Regardless of whether it is a closed CNC hydraulic pump with a single pump body or a double pump body, the suspended end of the sub-piston 11 is connected to the pin 13, and the pin 13 is provided with a mounting hole that can be externally connected and pivoted. Figure 1-3 In the embodiment, the ends of the sub-piston 11 are connected with a pin 13; Figure 4-5 In the figure, the end of the sub-piston 11 is not connected with the pin 13, which is the original structure, and it can also be flexibly matched with it through the pin 13 (omitted in the figure). Correspondingly, a fixing seat 12 for fixing is provided at the end where the rodless cavity end C in the sub-pump body 10 is located. This fixing seat 12 is also a flexibly connected structure with the cylinder of the sub-pump body 10 like the pin 13, and can be connected to the tail of the cylinder of the sub-pump body 10 when needed, such as Figure 1-3 If not needed, it can be disassembled, such as Figure 4-5 The sub-pump body 10 can be integrally connected with the mounted component through the pin shaft 13 and the fixing seat 12, so that the mounted component can be driven to move through the sub-pump body 10.

[0049] The closed CNC hydraulic pump proposed in this application uses "electromechanical-hydraulic coupling control" with an absolute servo motor as the motion reference and a ball screw as the displacement conversion core. It combines the rigid transmission characteristics of the hydraulic closed system to break through the response hysteresis and positioning error bottlenecks of traditional hydraulic valve control and is suitable for high-precision industrial scenarios. The hydraulic pump can achieve sub-micron positioning with a linear displacement resolution of 0.07um / Step, and can also reduce the error rate of thrust accuracy to less than 0.2%.

[0050] A robot is provided with a closed CNC hydraulic pump as described above on its arm, wherein a sub-pump body 10 is constructed on a large arm 60, a fixing seat 12 at the tail of the sub-pump body 10 is fixed on the side of the large arm 60 close to the scapula 80, and a suspended end of a sub-piston 11 is pivotally connected to the connecting shaft between the large arm and the small arm through a pin shaft 13.

[0051] like Figure 6 As shown, a robot arm controlled by a dual-pump closed CNC hydraulic pump is adopted, in which two main pump bodies 20 and a sub-pump body 10 are fixed together on the same side of a large arm 60, and the main pump body 20 with a short cylinder body 24 is arranged close to the side of the sub-pump body 10, and the rodless cavity end A of the short cylinder body 24 is connected with the rodless cavity end C of the sub-pump body 10 through a hose 30, and the rodless cavity end E of the long cylinder body 25 is connected with the rod cavity end D of the sub-pump body 10 through a hose 30, thereby forming a closed hydraulic cavity. The PLC controller uses electrical signals to control the operation of the servo motor 40, which in turn drives the ball screw 22 to rotate through the reducer 50, so that the ball screw 22 restricted by the guide rail drives the nut as the mother piston 21 to perform linear reciprocating motion; the nut is made into a hydraulic cylinder piston structure, so that the mother piston 21 can be controlled to reciprocate in the cylinder body in the mother pump body 20, and the hydraulic oil can be squeezed or sucked into the cylinder body in the sub-pump body 10 through a hose to drive the sub-pump body 10 to drive the small arm 70 to work, thereby adjusting the posture of the robot arm and realizing anthropomorphic adjustment.

[0052] like Figure 7 As shown, if space is limited, the sub-pump body 10 can be fixed on the upper arm 60, and the two main pump bodies 20 can be set on the thighs, and the hose 30 can be arranged close to the upper body of the robot, so that the sub-pump body 10 can drive the small arm 70 to adjust different postures. Of course, the two main pump bodies 20 can also be set externally according to actual conditions (the figure is omitted), and the sub-pump body 10 is connected to the main pump body 20 only through a pipeline, and the sub-pump body 10 can also drive the small arm 70 to adjust different postures.

[0053] Of course, for the structure of the sub-pump body 10 controlled by the single main pump body 20, the following can also be achieved: Figure 5-6 The connections shown will not be described in detail here and will be omitted from the drawings.

[0054] This CNC mother pump body 20 indirectly controls the distributed sub-pump bodies 10 through flexible pipes, which can break through the limitations of traditional hydraulic pumps and be applied to the robot's bionic spine, so that the sub-pump body 10 is embedded in the mechanical spine joints. Through remote control of the sub-pump body 10, it drives multiple joints and adjusts the joint center of gravity to adjust the human body posture and complete the corresponding action requirements. This achieves a leap in the load capacity and bionic motion performance of the humanoid robot, and its modular architecture provides an expandable hardware foundation for future high-dynamic scenarios such as rescue and nursing.

[0055] A closed CNC hydraulic pump designed by the present application includes a closed single pump body and a double pump body. Under the condition of a certain amount of oil, the mother pump body drives the sub-pump body to continuously reciprocate; the sub-pump body can be installed flexibly and is not limited by the size of the space range; it is easy to carry and its movement can be remotely controlled; not only is the output direction free, but the fixed-point stop position is accurate, the energy consumption is low, and it is safe and reliable. The present application also proposes a robot equipped with the closed CNC hydraulic pump.

[0056] The above detailed description of the embodiments of the present application is only a preferred embodiment of the present application and cannot be considered to limit the scope of implementation of the present application. All equivalent changes and improvements made within the scope of the present application should still fall within the scope of the patent coverage of the present application.

Claims

1. A closed CNC hydraulic pump, characterized in that: It comprises a sub-pump body and at least one main pump body, wherein the sub-pump body is connected to the main pump body via a hose to form a closed air-tight hydraulic chamber; the main pump body is driven by a servo motor to drive the sub-pump body to move synchronously.

2. A closed type CNC hydraulic pump according to claim 1, characterized in that: The servo motor is directly connected to the mother pump body through a reducer; the number of the hoses is two; the reducer is connected to the mother piston in the mother pump body through a ball screw.

3. A closed CNC hydraulic pump according to claim 1 or 2, characterized in that: The number of the mother pump bodies is one or two, and the number of the sub-pump bodies is one; the hydraulic chambers in each of the mother pump body and the sub-pump body are provided with a rodless chamber end and a rod chamber end.

4. A closed type numerically controlled hydraulic pump according to claim 3, characterized in that: When there is only one mother pump body, the servo motor is connected to the mother pump body through a reducer with a single output shaft; the diameter of the hydraulic cavity of the sub-pump body is the same as the diameter of the hydraulic cavity of the mother pump body.

5. A closed type numerically controlled hydraulic pump according to claim 4, characterized in that: One of the hoses is connected to the rodless cavity ends of the hydraulic cavities in the sub-pump body and the main pump body respectively; the other hose is connected to the rod cavity ends of the hydraulic cavities in the sub-pump body and the main pump body respectively.

6. A closed type numerically controlled hydraulic pump according to claim 3, characterized in that: When there are two mother pump bodies, one of them has a short cylinder and the other has a long cylinder; the servo motor is connected to the two mother pump bodies respectively through a reducer with dual output shafts.

7. A closed type numerically controlled hydraulic pump according to claim 6, characterized in that: One of the hoses is respectively connected to the rodless chamber end of the hydraulic chamber in the sub-pump body and the rodless chamber end of the mother pump body with the short cylinder body; the other hose is respectively connected to the rod chamber end of the hydraulic chamber in the sub-pump body and the rodless chamber end of the mother pump body with the long cylinder body.

8. A closed type numerically controlled hydraulic pump according to claim 7, characterized in that: The diameter of the short cylinder is greater than the diameter of the long cylinder.

9. A robot, characterized in that: A closed CNC hydraulic pump as described in any one of claims 1 to 9 is provided on its arm, the sub-pump body is constructed on the upper arm, the fixing seat at the tail of the sub-pump body is fixed on the side of the upper arm close to the scapula, and its suspended end is pivotally connected to the connecting shaft between the upper arm and the forearm through a pin shaft.

10. A robot according to claim 9, characterized in that: The mother pump body and the sub-pump body are arranged on the same side of the big arm or are arranged away from the big arm.

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