HYDRAULIC ACTUATOR WITH NO FRICTION AND ZERO LEAKAGE, AND ITS DRIVE SYSTEM

Abstract

A hydraulic actuator with no friction and zero leakage and its drive system are provided. The hydraulic actuator includes a thickened disc structure A and a thickened disc structure B. The second end face of the thickened disc structure A is connected with the first end face of the thickened disc structure B, and a control cavity is formed between the second end face of the thickened disc structure A and the first end face of the thickened disc structure B. The drive oil access hole is arranged on the thickened disc structure B, and the control cavity is connected with the drive oil access hole. The displacement output method based on elastic deformation is adopted, which completely avoids the nonlinear phenomena such as leakage and friction, and reduces the difficulty of high-precision control of the actuator.

Claims

1. A hydraulic actuator with no friction and zero leakage includes a thickened disc structure A and a thickened disc structure B; the second end face of the thickened disc structure A is connected to the first end face of the thickened disc structure B, and a control cavity is formed between the second end face of the thickened disc structure A and the first end face of the thickened disc structure B, a drive oil access hole is set on the thickened disc structure B, and the control cavity is connected with the drive oil access hole; a convex platform is set on the first end surface of the thickened disc structure A, and an installation flange is set on the second end surface of the thickened disc structure B.

2. The hydraulic actuator with no friction and zero leakage according to claim 1, wherein the second end face of the thickened disc structure A and the first end face of the thickened disc structure B are sealed with a seal ring.

3. The hydraulic actuator with no friction and zero leakage according to claim 1, the thickened disc structure A and the thickened disc structure B both include several stiffness-weakening areas and stiffness-enhanced areas, the stiffness-weakening areas and the stiffness-enhanced areas are alternately arranged along the radial direction of the thickened disc structure A and the thickened disc structure B.

4. The hydraulic actuator with no friction and zero leakage according to claim 1, wherein groove A is set on the second end surface of the thickened disc structure A, the second end surface of the thickened disc structure A is connected with the first end surface of the thickened disc structure B, a control cavity is formed by groove A.

5. The hydraulic actuator with no friction and zero leakage according to claim 1, wherein groove A is set on the second end surface of the thickened disc structure A, groove B is set on the first end surface of the thickened disc structure B, the second end surface of the thickened disc structure A is connected with the first end surface of the thickened disc structure B, a control cavity is formed by groove A and groove B.

6. The hydraulic actuator with no friction and zero leakage, wherein it includes a disc actuator I and a disc actuator II; both the disc actuator I and the disc actuator II include a thickened disc structure A and a thickened disc structure B; the second end face of the thickened disc structure A is connected to the first end face of the thickened disc structure B, and a control cavity is formed between the second end face of the thickened disc structure A and the first end face of the thickened disc structure B; the control cavity of the disc actuator I is connected to the control cavity of the disc actuator II, and a drive oil access hole is set on the thickened disc structure B of the disc actuator I; the drive oil access hole is connected with the control cavity of the disc actuator I.

7. A drive system for the hydraulic actuator with no friction and zero leakage is characterized by including a controller, a hydraulic pump, proportional valves, relief valves, several pressure sensors, and several hydraulic actuators with no friction and zero leakage according to any of the claims 1-5; the hydraulic pump is connected to the oil inlet of the proportional valve, and the oil outlet of the proportional valve is connected to the drive oil access holes of the hydraulic actuators with no friction and zero leakage, respectively; the relief valves are set on the connecting pipeline between the hydraulic pump and the oil inlet, and the connecting pipeline between the oil outlet and the drive oil access hole; the pressure sensors are used to obtain the control cavity pressure of each hydraulic actuator with no friction and zero leakage; the controller is used to calculate the output displacement of the hydraulic actuators with no friction and zero leakage according to the control cavity pressure; the output displacement is compared with the commanded displacement to obtain the control signal, the proportional valve is controlled by the control signal.

8. The drive system for the hydraulic actuator with no friction and zero leakage according to claim 7, wherein two hydraulic actuators with no friction and zero leakage and two pressure sensors are provided, the two outlets of the proportional valves are connected one by one with the two drive oil access holes.

9. The drive system for the hydraulic actuator with no friction and zero leakage according to claim 7, wherein four hydraulic actuators with no friction and zero leakage are provided, one outlet of the proportional valve is connected with two of the drive oil access holes, and the other outlet is connected with the other two drive oil access holes.

10. The drive system for the hydraulic actuator with no friction and zero leakage according to claim 7 wherein the hydraulic actuators with no friction and zero leakage are connected to a fixed bracket.

11. The drive system for the hydraulic actuator with no friction and zero leakage according to claim 7 wherein the hydraulic actuators with no friction and zero leakage are connected to a rotating platform through a ball hinge.

12. The drive system for the hydraulic actuator with no friction and zero leakage includes a controller, a hydraulic pump, a proportional valve, a relief valve, several pressure sensors, and several hydraulic actuators with no friction and zero leakage disclosed in claim 6; the hydraulic pump is connected with the inlet of the proportional valve, and the outlet of the proportional valve is connected with the drive oil access holes of the hydraulic actuators with no friction and zero leakage; the relief valves are set on the connection pipeline between the hydraulic pump and the inlet, and the connection pipeline between the outlet and the drive oil access hole; the pressure sensors are used to obtain the pressure in the control cavity of each hydraulic actuator with no friction and zero leakage; the controller is used to calculate the output displacement of the hydraulic actuators with no friction and zero leakage according to the pressure in the control cavity; the output displacement is compared with the commanded displacement to obtain the control signal, and the proportional valve is controlled by the control signal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings of the specification, which form part of this application, are used to provide a further understanding of this application. The schematic embodiments and descriptions of this application are used to explain this application and do not constitute an improper limitation of this application.

[0022] FIG. 1 is the first structural section view of the hydraulic actuator disclosed in Embodiment 1.

[0023] FIG. 2 is the side view of the hydraulic actuator disclosed in Embodiment 1;

[0024] FIG. 3 is the stress curve along the radius direction of the thickened disc structure of the hydraulic actuator disclosed in Embodiment 1.

[0025] FIG. 4 is the second structural section view of the hydraulic actuator disclosed in Embodiment 1.

[0026] FIG. 5 is the structural profile of the hydraulic actuator disclosed in Embodiment 2.

[0027] FIG. 6 is the schematic diagram of the first drive control loop of the open drive system disclosed in Embodiment 3.

[0028] FIG. 7 is the schematic diagram of the second drive control loop of the open drive system disclosed in Embodiment 3.

[0029] FIG. 8 is the schematic diagram of the third drive control loop of the open drive system disclosed in Embodiment 3.

[0030] FIG. 9 is the schematic diagram of the rotary drive application disclosed in Example 3.

[0031] FIG. 10 is the schematic diagram of the multi-group parallel drive application disclosed in Embodiment 3.

[0032] FIG. 11 is the schematic diagram of the multi-group series drive application disclosed in Embodiment 4.

[0033] Among them: 1, pump station motor; 2, hydraulic pump; 3, relief valve; 4, proportional directional valve; 5, relief valve; 6, relief valve; 7, disc actuator II; 8, fixed bracket II; 9, disc actuator I; 10, fixed bracket I; 11, pressure sensor; 12, pressure sensor; 13, driven platform; 14, controller; 15, the thickened disc structure A; 16, the thickened disc structure B; 17, seal ring; 18, installation flange; 19, flange thread hole; 20, drive oil access hole; 21, connecting screw; 22, seal groove; 23, stiffness weakening area; 24, stiffness enhanced area; 25, convex plate; 26, proportional pressure reducing valve; 27, proportional pressure reducing valve; 28, disc actuator II; 29, disc actuator I; 30, fixed bracket; 31, drive oil access hole; 32, rotating platform; 33, disc actuator I; 34, disc actuator II; 35, fixed ball hinge I; 36, fixed ball hinge II; 37, disc actuator I; 38, disc actuator II; 39, fixed bracket I; 40, disc actuator III; 41, disc actuator IV; 42, fixed bracket II; 43, driven platform, 44, tandem disc actuator I; 45, tandem disc actuator II; 46, fixed bracket H; 47, fixed bracket I; 48, driven platform.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] The following is a further explanation of the invention in combination with drawings and embodiments.

[0035] It should be noted that the following details are illustrative and are intended to provide further clarification of this application. Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as those commonly understood by ordinary technicians in the technical field to which this application relates.

[0036] It should be noted that the terminology used here is only to describe the specific embodiments, it is not intended to limit the examples of the embodiment in this application. As used here, the singular form is also intended to include the plural form unless explicitly stated in the context. In addition, it should be understood that when the terms include and/or comprise are used in this specification, they indicate the presence of features, steps, operations, devices, components, and/or combinations of them.

[0037] In this invention, terms such as up, down, left, right, front, back, vertical, horizontal, side, and bottom indicate the position or position relationship based on the position or position relationship shown in the attached figures, which is only a relation word determined to facilitate the description of the structural relationship of any accessory or component of the invention. It does not refer to any accessory or component in the invention and cannot be understood as a restriction on the invention.

[0038] In this invention, terms such as fixed connection, connect, link, etc. should be understood in a broad sense, indicating that it can be a fixed connection, an integrated connection, or a detachable connection; it can be directly connected or indirectly connected through an intermediary. For the relevant scientific research or technical personnel in this field, the specific meaning of the above terms in the invention can be determined according to the specific situation, which cannot be understood as a restriction on the invention.

Embodiment 1

[0039] In this embodiment, a hydraulic actuator with no friction and zero leakage is disclosed, as shown in FIGS. 1-4, including a thickened disc structure A and a thickened disc structure B. The second end face of the thickened disc structure A is connected with the first end face of the thickened disc structure B, and a control cavity is formed between the second end face of the thickened disc structure A and the first end face of the thickened disc structure B. A drive oil access hole is set on the thickened disc structure B, the control cavity is connected with the drive oil access hole, and the drive oil access hole is connected to the control cavity.

[0040] As shown in FIG. 1 and FIG. 4, a convex plate 25 is set on the first end face of the thickened disc structure A 15. The convex plate 25 is circular and is located at the center of the thickened disc structure A 15. The displacement of the hydraulic actuator disclosed in this embodiment is output through the convex plate 25, and the installation flange 18 is connected to the second end face of the thickened disc structure B 16. The hydraulic actuator disclosed in this embodiment is fixed with the fixed bracket by installation flange 18, and the installation flange 18 and the fixed bracket are bolted through the flange thread hole 19 for bolt connection.

[0041] A drive oil access hole 20 is connected to the high-pressure tube, and the hydraulic oil is introduced into the control cavity by the drive oil access hole 20. Under the action of the hydraulic oil, the thickened disc structure A 15 and the thickened disc structure B16 are elastically deformed so that the displacement can be output.

[0042] To ensure the sealing performance of the hydraulic actuator and prevent the oil from leaking, a seal ring 17 is installed between the second end face of the thickened disc structure A 15 and the first end face of the thickened disc structure B 16. Specifically, a seal groove 22 is set on the second end face of the thickened disc structure A 15, and the seal ring 17 is installed in the seal groove 22. The seal ring 17 is used for preventing the hydraulic oil in the control cavity from leaking in the junction of the second end face of the thickened disc structure A 15 and the first end face of the thickened disc structure B16, the optimal choice of the seal ring 17 is an O-ring.

[0043] The thickened disc structure A 15 and the thickened disc structure B 16 include a plurality of stiffness weakening areas 23 and stiffness enhanced areas 24. The stiffness weakening areas 23 and the stiffness enhanced areas 24 are alternately arranged along the radial direction of the thickened disc structure A 15 and the thickened disc structure B 16. By alternately arranging the stiffness enhanced areas 24 and the stiffness weakening areas 23, the stress distribution along the radius direction is optimized, the stress concentration of the thickened disc structure is reduced, and the deformation of the thickened disc structure is fully utilized. As shown in FIG. 3, it is the equivalent stress diagrams of the disc structure along the radius direction of the stiffness enhanced area and the stiffness weakening area alternate one time before optimization, and the stiffness enhanced area and the stiffness weakening area alternate three times after optimization, respectively.

[0044] The thickened disc structure A 15 and the thickened disc structure B 16 are connected by a connecting screw 21.

[0045] The groove A is set on the second end face of the thickened disc structure A15, and the groove B is set on the first end face of the thickened disc structure B 16. The second end face of the thickened disc structure A 15 is connected with the first end face of the thickened disc structure B 16. The control cavity is formed by the groove A and the groove B. The bottom of the groove A and the bottom of the groove B both include a plurality of stiffness weakening areas and stiffness enhanced areas. The stiffness weakening areas of the groove A and the groove B are set relatively, and the stiffness enhanced areas are set relatively to form a control cavity.

[0046] In the specific implementation, the thickened disc structure B can also adopt a fixed bracket 30, and a drive oil access hole 31 connected to the control cavity is set on the fixed bracket 30.

[0047] As shown in FIG. 4, groove A is only set on the second end face of the thickened disc structure A. The second end face of the thickened disc structure A is connected with the first end face of the thickened disc structure B. The control cavity is formed by groove A, and a plurality of stiffness weakening areas and stiffness enhanced areas are only set at the bottom of groove A.

[0048] The hydraulic actuator with no friction and zero leakage disclosed in this embodiment, for the area of the control cavity between the thickened disc structure A and the thickened disc structure B, as well as the thickness of the stiffness enhanced area and the stiffness weakening area, the number of alternate arrangements should be determined according to the volume limit of the hydraulic actuator disclosed in this embodiment and the mechanical properties of the manufacturing material, and the design of key size parameters should be completed under the condition of ensuring the fatigue strength of the actuator.

[0049] The hydraulic actuator with no friction and zero leakage disclosed in this embodiment outputs the axial displacement based on the elastic deformation of the material, adopts the design of a static seal, and there is no motion pair inside the structure, which effectively avoids the inherent friction, leakage, hysteresis, creep and other nonlinear characteristics of the traditional hydraulic actuators, and reduces the difficulty of high-precision displacement and force control. The end face of the static seal is sealed with a seal ring, which has low processing accuracy requirements and greatly reduces manufacturing costs. At the same time, there is no motion pair inside the actuator, which has the characteristics of a simple structure and small axial size.

[0050] The stiffness enhanced areas and the stiffness weakening areas are alternately arranged in the thickened disc structure of the actuator. On this basis, the sizes of the stiffness weakening area and the stiffness enhanced area are optimized according to the material stress limit, which reduces the stress concentration and gives full play to the deformation of the disc structure. At the same time, the stiffness of the actuator is designable, and different stiffness actuators can meet different stroke requirements.

Embodiment 2

[0051] In this embodiment, a hydraulic actuator with no friction and zero leakage is disclosed as shown in FIG. 5, it is a series disc actuator, including a disc actuator I and a disc actuator II. Both the disc actuator I and the disc actuator II include a thickened disc structure A and a thickened disc structure B. The second end face of the thickened disc structure A is connected to the first end face of the thickened disc structure B, and a control cavity is formed between the second end face of the thickened disc structure A and the first end face of the thickened disc structure B. The control cavity of the disc actuator I is connected to the control cavity of the disc actuator II. The drive oil access hole is set on the thickened disc structure B of the disc actuator I, and the drive oil access hole is connected to the control cavity of the disc actuator I.

[0052] A convex platform is set on the first end face of the thickened disc structure A in the disc actuator II, and an installation flange is set on the second end face of the thickened disc structure B in the disc actuator I.

[0053] The thickened disc structure A and the thickened disc structure B both include a plurality of stiffness weakening areas and stiffness enhanced areas. The stiffness weakening areas and the stiffness enhanced areas are alternately arranged along the radial direction of the disc actuator I.

[0054] The hydraulic actuator with no friction and zero leakage disclosed in this embodiment realizes the series connection of two disc actuators and improves the stroke of the hydraulic actuator.

Embodiment 3

[0055] In this embodiment, a drive system for the hydraulic actuator with no friction and zero leakage is shown in FIGS. 6-11, including a controller 14, a hydraulic pump 2, a proportional valve, relief valves, pressure sensors, and a plurality of hydraulic actuators with no friction and zero leakage disclosed in Embodiment 1. The hydraulic pump 2 is connected to the oil inlet of the proportional valve, and the oil outlet of the proportional valve is connected to the drive oil access holes of the hydraulic actuators with no friction and zero leakage, respectively. The relief valves are set on the connection pipeline between the hydraulic pump 2 and the oil inlet, and the connection pipeline between the oil outlet and the drive oil access hole. The pressure sensor is used to obtain the pressure of each control cavity of the hydraulic actuators with no friction and zero leakage. The proportional valve and pressure sensors are connected with the controller. The controller is used to calculate the output displacement of the hydraulic actuators with no friction and zero leakage according to the pressure of the control cavity. The output displacement is compared with the commanded displacement to obtain the control signal. The proportional valve is controlled by the control signal.

[0056] The hydraulic pump 2 is driven by pump station motor 1 to output high-pressure oil.

[0057] The proportional valve is a proportional directional valve, a proportional pressure-reducing valve, a proportional relief valve, or a servo directional valve.

[0058] Two hydraulic actuators with no friction and zero leakage and two pressure sensors are provided, and the two outlets of the proportional valves are connected one by one with the two drive oil access holes.

[0059] Or four hydraulic actuators with no friction and zero leakage are provided, one outlet of the proportional valve is connected with two of the drive oil access holes, and the other outlet is connected with the other two drive oil access holes.

[0060] The hydraulic actuators with no friction and zero leakage are connected to a fixed bracket.

[0061] Or the hydraulic actuators with no friction and zero leakage are connected to a rotating platform through a ball hinge.

[0062] The following is the detailed description of the drive system for the hydraulic actuator with no friction and zero leakage disclosed in this embodiment.

[0063] As shown in FIG. 6, the proportional valve adopts the proportional directional valve 4, which includes two hydraulic actuators with no friction and zero leakage disclosed in Embodiment 1, which are disc actuator I 9 and disc actuator II 7, respectively. The hydraulic pump 2 is connected with the oil inlet of the proportional directional valve 4, and the oil outlet of the proportional directional valve 4 is connected with the drive oil access holes of the disc actuator I 9 and the disc actuator II 7, respectively. The relief valve 3 is set on the connection pipeline between the hydraulic pump 2 and the oil inlet, and the relief valve 5 is set on the connection pipeline between the oil outlet of the proportional directional valve 4 and the drive oil access hole of the disc actuator I 9. The relief valve 6 is set on the connecting pipe of another outlet of the proportional directional valve 4 and the drive oil access hole of the disc actuator II 7. The pressure sensor 12 is set to obtain the pressure of the disc actuator I 9 to control the cavity pressure, and the pressure sensor 11 is set to obtain the pressure of the disc actuator II 7 to control the cavity pressure. The proportional directional valve 4, and the pressure sensor 11 and 12 are connected with the controller 14. The controller 14 is used to calculate the output displacement of the disc actuator I 9 and the disc actuator II 7 according to the control cavity pressure obtained by the pressure sensors 11 and 12. The output displacement is compared with the commanded displacement to obtain the control signal, and the proportional directional valve 4 is controlled by the control signal.

[0064] Among them, the pump station motor 1 drives the hydraulic pump 2 to output high-pressure oil, the relief valve 3 controls the output pressure of the hydraulic pump 2, the proportional directional valve 4 controls the flow direction and flow rate of the high-pressure oil flowing into the disc actuator II 7 and the disc actuator I 9, the disc actuator II 7 is fixed with the fixed bracket II 8, the disc actuator I 9 is fixed with the fixed bracket I 10, the relief valve 5 limits the maximum value of the cavity pressure p1 of the disc actuator I 9, and the relief valve 6 limits the maximum value of the cavity pressure p2 of the disc actuator II 7; the pressure sensor 12 monitors the control cavity pressure p1 of the disc actuator I 9 in real time, the pressure sensor 11 monitors the control cavity pressure p2 the disc actuator II 7 in real time; the controller 14 calculates the real-time output displacement x=A1(p1?p2)/k1 according to the pressure signals p1 and p2 monitored by the pressure sensor 12 and 11, the overall stiffness k1 and the action area A1 of the disc actuator I 9 and the disc actuator II 7, and compares it with the command displacement f. The difference between the commanded displacement and the real-time displacement ?=f?x is processed and the control signal u is output to the proportional directional valve 4. The control cavity pressure difference p1?p2 of the disc actuator I 9 and the disc actuator II 7 is changed by controlling the opening and direction of the proportional directional valve and the purpose of closed-loop control of the displacement of the driven platform 13 is realized. At this time, the driving force F=A1(p1?p2)/2 of the driven platform 13.

[0065] The proportional directional valve 4 can also be replaced by a proportional relief valve or a servo directional valve, and the oil circuit is the same as the above oil circuit.

[0066] As shown in FIG. 7, the proportional relief valves 26 and 27 can also be used instead of the proportional directional valve 4 to connect the hydraulic pump 2 with one end of the first tubing, the other end of the first tubing is connected with the second tubing and the third tubing respectively. The second tubing and the third tubing are connected with the inlets of the proportional relief valves 26 and 27 respectively. The outlet of the proportional relief valve 26 is connected with the drive oil access hole of the disc actuator II 7. The outlet of the proportional relief valve 27 is connected with the drive oil access hole of the disc actuator I 9. The relief valve 6 is set on the connection pipeline between the outlet of the proportional relief valve 26 and the drive oil access hole of the disc actuator II 7. The relief valve 5 is arranged on the connection pipeline between the oil outlet of the pressure-reducing valve 27 and the drive oil access hole of the disc actuator I 9, and the relief valve 3 is arranged on the first tubing.

[0067] When the axial size is tight, as shown in FIG. 8, the disc actuator I 9 and the disc actuator II 7 can be replaced by the hydraulic actuators with no friction and zero leakage with only groove A on the second end face of the thickened disc structure A, and the control cavity is formed by the groove A. The disc actuator I 29 and the disc actuator II 28.

[0068] In the case of a rotating drive, as shown in FIG. 9, there are two hydraulic actuators with no friction and zero leakage disclosed in Embodiment 1, which are disc actuator I 33 and disc actuator II 34, respectively. The disc actuator I 33 is connected to the rotating platform 32 through the ball hinge O1, and it is connected to the fixed ball hinge I 35 through the ball hinge O3. The disc actuator II 34 is connected to the rotating platform 32 through the ball hinge O2, and it is connected to the fixed ball hinge II 36 through the ball hinge O4. The control cavity pressure p1 and p2 of the disc actuator I 3 and the disc actuator II 34 can realize the valve group control of the pressure closed-loop control through the proportional valves. The overall stiffness k3, the action area A3, and the arm of force L from O1 and O2 to O of the disc actuator I 33 and the disc actuator II 34 are known. Under the action of the pressure difference p1?p2 in the control cavity, the disc actuator I 33 and the dis actuator II 34 output displacements, and furthermore, the rotation angle of the rotating platform 32 around the axis O is ?=arctan (A3(p1?p2)/(k3L)). According to the angle and the command angle, the control signal is output and the proportional valve is controlled by the control signal. Furthermore, the pressure difference p1?p2 of the control cavity of the disc actuator I 33 and the disc actuator II 34 is controlled to achieve the purpose of controlling the rotation angle of the rotating platform 32.

[0069] When a large driving force is required, as shown in FIG. 10, four hydraulic actuators with no friction and zero leakage disclosed in Embodiment 1 are included, namely: disc actuator I 37, disc actuator II 38, disc actuator III 40, disc actuator IV 41.

[0070] Disc actuator I 37 and disc actuator II 38 are symmetrically arranged with disc actuator III 40 and disc actuator IV 41. Disc actuator I 37 and disc actuator II 38 are fixed with the fixed bracket I 39, the disc actuator III 40 and disc actuator IV 41 are fixed with the fixed bracket H 42, and the fixed bracket I 39 and the fixed bracket II 42 are fixed with each other. One outlet of the proportional valve is connected with the drive oil access hole of the disc actuator I 37 and the disc actuator II 38, and the other outlet is connected with the drive oil access hole of the disc actuator II 40 and the disc actuator IV 41. The internal control cavity pressure p1 of the disc actuator I 37 and disc actuator II 38, and the internal control cavity pressure p2 of the disc actuator III 40 and disc actuator IV 41 can realize the valve group control of pressure closed-loop control through the proportional valve; the overall stiffness k4 and the action area A4 of the disc actuator I 37 and the disc actuator II 38, and the disc actuator III 40 and the disc actuator IV 41 are known. Under the action of the pressure difference p1?p2 of the control cavity, the output displacement of the driven platform 43 is driven to output displacement x=A4(p1?p2)/k4. The output displacement is compared with the commanded displacement, and the control signal is output. The proportional valve is controlled by the control signal to control the displacement of the driven platform 43. At this time, the driving force of the driven platform 43 is F=A4 (p1?p2)/2.

[0071] The proportional valve is a proportional directional valve, a proportional pressure-reducing valve, a proportional relief valve, or a servo directional valve.

[0072] The drive system for the hydraulic actuator with no friction and zero leakage disclosed in this embodiment can realize high frequency and high precision displacement and force control of the hydraulic actuators with no friction and zero leakage using electro-hydraulic servo control.

Embodiment 4

[0073] In this embodiment, a drive system for the hydraulic actuator with no friction and zero leakage is disclosed, including a controller, a hydraulic pump, proportional valves, relief valves, a plurality of pressure sensors, and a plurality of hydraulic actuators with no friction and zero leakage disclosed in Embodiment 2. The hydraulic pump is connected to the oil inlet of the proportional valve, and the oil outlet of the proportional valve is connected to the oil access holes of the hydraulic actuators with no friction and zero leakage, respectively. The relief valves are set on the pipeline connecting the hydraulic pump and the oil inlet, and the pipeline connecting the oil outlet and the oil access hole. The pressure sensors are used to obtain the pressure in the control cavity of each hydraulic actuator with no friction and zero leakage. The controller is used to calculate the output displacement of the hydraulic actuators with no friction and zero leakage according to the pressure in the control cavity. The output displacement is compared with the commanded displacement to obtain the control signal, and the proportional valve is controlled by the control signal.

[0074] The difference between this embodiment and Embodiment 3 is as follows: As shown in FIG. 11, the hydraulic actuator with no friction and zero leakage disclosed in Embodiment 1 and Embodiment 3 is replaced by the hydraulic actuator with no friction and zero leakage disclosed in Embodiment 2, which is a series disc actuator I 44 and a series disc actuator II 45, a series disc actuator I 44 and a series disc actuator II 45 symmetrically arranged, respectively, and they are fixed with the fixed bracket I 47 and the fixed bracket II 46, the fixed bracket I 47 and the fixed bracket II 46 are fixed with each other respectively. The control cavity pressure p1 and p2 of the series disc actuator I 44 and the series disc actuator II 45 can realize the valve group control of the pressure closed-loop control through the proportional valve, and the rest connections are the same as those of the embodiment 3. The overall stiffness k5 and the area A5 of the tandem disc actuator I 44 and the tandem disc actuator II 45 are known. Under the action of the pressure difference p1?p2 in the control cavity, the output displacement x=A5(p1?p2)/k5 of the driven platform 48 is driven. The output displacement is compared with the commanded displacement, and the control signal is output. The proportional valve is controlled by the control signal to control the displacement of the driven platform 48. At this time, the driving force F=A5(p1?p2)/2 of the driven platform 48.

[0075] The drive system for the hydraulic actuator with no friction and zero leakage disclosed in this embodiment can output large displacement through a series structure, which is suitable for use in scenarios requiring large strokes.

[0076] Finally, it shall be noted that the above embodiments are only used to explain the technical solution of the present invention and shall not be construed as a limitation thereto. Although the present invention is described in detail with reference to preferred embodiments, those of ordinary skill in the art shall understand that they still can modify or equivalently substitute the technical solution of the present invention. These modifications or equivalent substitutions do not deviate the modified technical solution from the spirit and scope of the technical solution of the present invention.