Integrated electro-static pressure actuator

Abstract

The invention discloses an integrated electro-static pressure actuator, and belongs to the technical field of actuator design. The electro-static pressure actuator comprises an actuating cylinder, an oil immersion type motor pump, an integrated shell, a pump front end cover, an oil tank, a filling valve, a bypass valve, an oil supplementing one-way valve and a motor rear end cover. Wherein the integrated shell and the pump front end cover are designed based on an additive manufacturing process method, an internal flow channel is self-formed, and other parts and components are mounted in the 3D printed integrated shell. Through the design of the invention, the electro-static pressure actuator realizes maximum structural integration, and has the advantages of small size and light weight.

Description

Technical Field

[0001] The present invention relates to an electrostatic actuator, and in particular to an integrated electrostatic actuator. Background Art

[0002] As a type of electric actuator, electrostatic actuators are used in high-end equipment such as aviation, aerospace, and robotics due to their outstanding advantages such as strong heavy-load capacity, high power density, and high reliability. Current patents for electrostatic actuators mainly involve system redundancy design and design for special applications or functional requirements. With the further reduction in the installation space of aviation and aerospace vehicle control surfaces and the increasing demand for high-load capacity and high-burst robot joints, higher requirements are placed on the miniaturization, integration, and high power density of electrostatic actuators.

[0003] Chinese patent CN111637104A discloses a coaxial modular triple-redundant electrostatic actuator with a coaxial layout and modular design. The actuator module, the redundancy management module, and the triple-redundant servo motor pump module are connected by bolts, and the sensor and valve assembly are integrated into the redundancy management module. The system has a high degree of integration and is easy to replace modules. However, the system has many connection interfaces, which increases the risk of hydraulic leakage. The redundancy management module is complex to design and process.

[0004] Chinese patent CN110202608B discloses a highly compact electrostatic actuator for robot joints. The actuator is designed to integrate a servo motor, a hydraulic pump, and a piston rod into a common shell. The design has a higher degree of integration. The motor pump assembly and the actuator cylinder composed of the motor and the pump are arranged in parallel. The structural design mainly considers the installation requirements on the robot joints. However, the overall design is still a structural design carried out under the traditional material removal processing technology. The integrated shell is relatively complex and cumbersome in design. It is inevitable to add process flow channels to achieve flow channel reversal. While increasing the flow resistance, it is also necessary to add corresponding process plugs to close the process flow channel entrance that passes through the outside of the integrated shell. The design, processing, and inspection are relatively time-consuming and labor-intensive, and the structural compactness is not high enough.

[0005] Chinese patent CN21886299U discloses a compact miniaturized electrostatic hydraulic actuator that uses a split layout scheme of the actuator assembly, micro pump, hydraulic valve, and magnetostrictive sensor. The use of the micro pump and magnetostrictive sensor facilitates overall miniaturization, but structural parts such as the actuator cylinder and hydraulic valve block are processed using a material removal process, and the motor and pump are connected using a coupling, which increases the number of connection and sealing interfaces and reduces the degree of integration of the overall structure. Summary of the Invention

[0006] The technical problem solved by the present invention is to overcome the deficiencies of the prior art and propose an integrated electrostatic actuator to improve the compactness of the structure, the power-to-weight ratio, and shorten the design and production cycle.

[0007] The technical solution of the present invention is:

[0008] An integrated electrostatic actuator comprises an actuator cylinder, an oil-immersed motor pump, an integrated housing, a pump front end cover, an oil tank, a filling valve, a bypass valve, an oil replenishment check valve and a motor rear end cover;

[0009] The integrated housing includes six areas, with area one located at the central axis of the integrated housing, area two located below area one, and the remaining areas located above area one; area one is a cylindrical structure with an actuator installed in its inner cavity; area two is a cylindrical structure with an oil-immersed motor pump installed in its inner cavity; area three is equipped with a filling valve and an oil replenishment check valve; area four is equipped with an oil tank and an oil replenishment check valve; area five is equipped with a sealing connector; and area six is ​​equipped with a bypass valve.

[0010] At the end of area 2, the inner cavity branches into three flow channels. The center is the first flow channel, flanked by the second and third flow channels. The first flow channel extends along the inner cavity of area 2, passes through area 2, and then extends to areas 3 and 4 in sequence, forming a hydraulic chamber A. The oil output from the bellows tank flows into the chamber.

[0011] A fourth flow channel and a fifth flow channel are provided at the outer edge of the end of region 2 and extend along the side of region 2 opposite to region 1, respectively. The other ends of the flow channels are connected to the two ends of the actuator in region 1 respectively.

[0012] The pump front cover is mounted on the end of area 2 and is provided with five flow channel openings, connecting the first flow channel to the fifth flow channel respectively. A connecting pipe is provided on the lower surface of the pump front cover, connecting the second flow channel with the fourth flow channel, and the third flow channel with the fifth flow channel. The second flow channel and the fourth flow channel form a hydraulic chamber B, and the third flow channel and the fifth flow channel form a hydraulic chamber C.

[0013] The bypass valve connects the hydraulic chamber A, the hydraulic chamber B and the hydraulic chamber C.

[0014] Furthermore, the actuator is a single-rod symmetrical cylinder design, including a piston rod, a middle rod, a front end cover of the actuator, a front support lug, a rear support lug and a feedback potentiometer;

[0015] The front end cover of the actuator is installed at the front of area 1. An arc-shaped pipeline is set inside the front end cover of the actuator to connect the fourth flow channel and the fifth flow channel, so as to communicate the two oil inlet and outlet ports on the end face of the oil-immersed motor pump with the inner cavity of the actuator;

[0016] The piston rod is unilaterally extended, and the inner and outer sides of the piston rod are connected to the fourth flow channel and the fifth flow channel respectively;

[0017] The body of the feedback potentiometer is fixed to the integrated housing by means of a rear lug, and the movable part is fixed to the piston rod by means of a front lug.

[0018] Furthermore, the oil-immersed motor pump includes a motor, a plunger pump, a rear end cover of the motor, and a distribution plate;

[0019] The distribution plate is located at the end of the second area, dividing the inner cavity of the second area into three flow channels, namely the first flow channel, the second flow channel and the third flow channel;

[0020] The plunger pump and the valve plate are mechanically sealed, and there is a gap. When the oil pressure in any hydraulic chamber is high, the oil will leak through the gap to the other two hydraulic chambers.

[0021] The motor is located on the output side of the plunger pump, and the rear end cover of the motor is installed at the other end of area 2;

[0022] The front cover of the pump is installed on the end where the distribution plate is located.

[0023] Furthermore, the area 2 is a cylindrical structure with a small front end and a large rear end. The plunger pump has a smaller outer diameter than the motor. The plunger pump is placed at the front end of the inner cavity of area 2, and the motor is placed at the rear end of the inner cavity of area 2.

[0024] Furthermore, an arc-shaped groove is provided at the rear end of the region one, connecting the first flow channel and the region five, and the output wires of the motor stator and the rotary transformer are led to the sealed connector through the arc-shaped groove.

[0025] Furthermore, the integrated housing and the pump front cover are designed based on additive manufacturing process methods, and the internal flow channel is self-forming.

[0026] Furthermore, the oil filling the valve enters the hydraulic chamber C through the oil replenishment one-way valve, and the oil in the oil tank enters the hydraulic chamber B through the oil replenishment one-way valve.

[0027] Furthermore, each flow channel adopts an arc transition design at the reversal point to reduce flow resistance.

[0028] Furthermore, the integrated shell is also provided with area seven, which is located above area two and between area four and area five; area seven is an elliptical cylindrical structure, and the inner cavity is equipped with a pressure core.

[0029] Furthermore, the integrated shell is also provided with area eight, which is located above area two and between area four and area five; area eight is a cylindrical structure, the inner cavity of which is equipped with a safety valve and connected to the hydraulic chamber A; when the oil pressure in the hydraulic chamber A exceeds the set safety value, the oil leaks from the safety valve.

[0030] The advantages of the present invention compared with the prior art are:

[0031] (1) The present invention adopts a fully integrated design scheme, installing all parts and components such as the motor pump, actuator, bellows oil tank, safety valve, pressure sensor, etc. on a 3D printed housing to achieve maximum structural integration to achieve small size and light weight.

[0032] (2) The present invention adopts an end cover with an arc-shaped pipeline arranged inside, which connects the two oil inlet and outlet ports on the end face of the motor pump with the two-chamber oil circuits of the actuator on the oil circuit block, thereby realizing the oil distribution of the two chambers of the motor pump and the actuator in the common shell, avoiding the large-volume external pipeline structure, and having good compactness.

[0033] (3) The present invention adopts an actuator cylinder with a single-rod symmetrical design, and the axis has only a rear support ear structure. An adjustment gasket is used to fix the embedded feedback potentiometer and fine-tune the actuator stroke range, eliminating the axial length required for the threaded connection structure. Under the same stroke design index, the axial installation length is further saved.

[0034] (4) The motor pump in the present invention adopts a small outer diameter pump and a large outer diameter motor, and an overall oil-immersed design. The motor pump housing forms a connection part in the area shared by the motor end and the actuator cylinder. The size of the pump end is just used to design the mechanical and oil circuit connection interface. The oil circuit is close to the connection part between the motor pump and the actuator cylinder, which not only enhances the connection strength but also saves the overall volume.

[0035] (5) The present invention forms an arc-shaped inner pipe in the 3D printed housing block, buries the power cable of the motor pump and the signal cable of the rotary transformer, and eliminates external wiring. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present invention. The same reference symbols are used throughout the drawings to represent the same components. In the drawings:

[0037] Figure 1 This is a front view of an electrostatic actuator according to an embodiment of the present invention;

[0038] Figure 2 This is a right side view of an electrostatic actuator according to an embodiment of the present invention;

[0039] Figure 3 A three-dimensional diagram of an electrostatic actuator according to an embodiment of the present invention;

[0040] Figure 4 This is a three-dimensional diagram of the integrated housing of the electrostatic actuator according to an embodiment of the present invention;

[0041] Figure 5 This is a three-dimensional view of the front end cover of the electrostatic actuator pump according to an embodiment of the present invention. DETAILED DESCRIPTION

[0042] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0043] The present invention proposes an integrated electrostatic actuator, which is suitable for situations where the demand matches the actuator design parameters, especially in scenarios where the power-to-weight ratio of the actuator is required to be high.

[0044] The electrostatic actuator Figures 1 to 3 As shown, it includes a piston rod 1, a middle rod 2, a front end cover of the actuator 3, a rear support ear 4, a front support ear 5, a rotary transformer 6, a bypass valve 7, a pressure core 8 (2 pcs), a plunger pump 9, a front end cover of the pump 10, a filling valve 11, a bellows oil tank 12, a rotor shaft 13, a rear end adjustment gasket 14, a safety valve 15, a motor stator 16, a front end adjustment gasket 17, a rear end cover of the motor 18, a feedback potentiometer 19, a distribution plate 20, a sealing connector 21, an integrated housing 22, an oil plug 23 and an oil replenishment check valve 24 (2 pcs).

[0045] The integrated housing 22 serves as both a hydraulic channel and a structural support. Structurally, it can be divided into eight blocks, which are connected together through the outer wall. Figure 1 As shown, area 1 is at the center, area 2 is below, and the remaining areas are above. Areas 3 and 4 are side by side on the left, area 5 and area 8 are side by side on the right, and area 6 and area 7 are located between area 4 and area 5.

[0046] Area 1 is the cylindrical structure where the piston rod 1, the middle rod 2, and the front cover 3 of the actuator are installed and its rearward ( Figure 1 A square portion extending to the right for mounting the feedback potentiometer 19 body, the rear end adjustment gasket 14 and the rear support ear 4 components.

[0047] Area 2 is a cylindrical structure with a small front end and a large rear end where the motor stator 16, rotor, plunger pump 9, resolver 6 and other components are installed. The pump is placed at the front end and the motor is placed at the rear end. The size left at the pump end is just enough for the design of the mechanical and oil circuit connection interface, such as Figure 4 and Figure 5As shown, the main oil circuit connecting the two oil ports of the motor pump with the two chambers of the actuator is located precisely at the intersection of the motor pump and the actuator's outer wall, between the pump front cover 10 and the integrated housing 22. Two of the four threaded connection holes are located between the motor pump and the cylindrical surface of the actuator, and two hydraulic interfaces are also located nearby. Besides the necessary sealing and connection structure strength, the pump front cover 10 has only two internal flow channels with 180° reversing inlet and outlet directions, connecting the B / C chambers in area 1 of the integrated housing 22 with the corresponding B / C chambers in area 2. The reversing channels use a curved transition design to effectively reduce the pressure loss along the flow path caused by the flow channel reversal.

[0048] Area three is the cylindrical structure where the filling valve 11 and the oil replenishment one-way valve 24 are installed.

[0049] Area four is the cylindrical structure where the bellows oil tank 12 and the oil replenishment one-way valve 24 are installed.

[0050] Area five is the block structure where the sealed connector 21 is installed.

[0051] Area six is ​​the cylindrical structure where the bypass valve 7 is installed.

[0052] Area seven is the elliptical cylindrical structure where the pressure cores 8 (2) are installed.

[0053] Area eight is the cylindrical structure where the low-pressure safety valve is installed.

[0054] The components are installed in the corresponding chambers in each area of ​​the integrated housing 22, and the components are connected to the integrated housing 22 using threaded structural parts. The sealing structure closes and divides the chamber to form three types of hydraulic cavities, such as Figure 1 As shown, the oil pressure in hydraulic chamber B and hydraulic chamber C may reach high pressure of 20 MPa during the operation of the mechanism. The oil pressure in hydraulic chamber C is relatively low, below 3 MPa. If it exceeds 3 MPa, some oil will be discharged through the safety valve 15 to ensure that the pressure in chamber C is not too high.

[0055] The flow channels are arranged along the intersections between the regions, connecting the corresponding hydraulic cavities and the hydraulic interfaces of the components. The flow channel reversals are all arc-shaped transitions to reduce the fluid pressure loss caused by the reversal, while the flow channel walls strengthen the connection strength between the regions.

[0056] The piston rod 1, center rod 2, actuator front cover 3, feedback potentiometer 19 body, and integrated housing 22 area 1 form the actuator cylinder function (a single-rod symmetrical cylinder design, with the piston rod extending from one side and the same effective hydraulic area on both sides of the piston). The feedback potentiometer 19 body is secured to the integrated housing 22 using the rear lug 4 and rear adjustment shim 14. The movable component is secured to the piston rod 1 via the front lug 5 and front adjustment shim 17. By fine-tuning the axial dimension of the front adjustment shim 17, the actuator travel range can be fine-tuned. The cavity in area 1 is divided into three parts. When the hydraulic oil pressure in hydraulic chamber B on the inner side of the piston rod is higher than that in hydraulic chamber C on the outer side, the piston rod is extended (moved to the left). When the hydraulic oil pressure in hydraulic chamber C on the inner side of the piston rod is higher than that in hydraulic chamber B on the outer side, the piston rod is retracted (moved to the right). The right end of the piston rod is a movable cavity, which is open to the air.

[0057] The pump front end cover 10, motor stator 16, rotor 26, plunger pump 9, resolver 6, motor rear end cover 18, distribution plate 20 and integrated housing 22 in area 2 constitute an oil-immersed motor pump. At the same time, the pump front end cover 10 and distribution plate 20 divide the area 2 chamber into three parts. The oil pump outlet forms a hydraulic chamber B and a hydraulic chamber C separately, which are connected to the B / C type chambers in area 1 through two flow channels in the pump front end cover 10, and the rest are hydraulic chambers A. The distribution plate 20 and the plunger pump 9 are mechanically sealed, and there is a gap. In the high-pressure chamber, the oil will slowly leak to the other two hydraulic chambers through the gap. There is an arc-shaped groove at the rear end of area 1, which belongs to the A type chamber, connecting the A type hydraulic chambers in area 1 and area 5. Figure 2 As shown, the outgoing wires of the motor stator 16 and the resolver 6 are led to the sealed connector 21 through this arc-shaped slot and then led out through the pins on the sealed connector 21 .

[0058] In area 3, the filling valve 11 is located in the Class A hydraulic chamber, where oil can enter the Class C chamber through the oil-replenishing check valve 24. A flow path connects the oil port of the oil-replenishing check valve 24 with the Class C chamber in area 1 and is located along the outer wall of the cylindrical structure in area 1. In area 4, the bellows oil tank 12 is located in the Class A hydraulic chamber, where oil can enter the Class B chamber through the oil-replenishing check valve 24. A flow path connects the oil port of the oil-replenishing check valve 24 with the Class B chamber in area 1 and is located along the outer wall of the cylindrical structure in area 1. The oil path between the filling valve 11 and the bellows oil tank 12 in the Class A chamber is connected.

[0059] The bypass valve 7 in area six has three oil ports that are interconnected. When in the "bypass" state, it will serve as an oil circuit section to connect the three types of hydraulic cavities on the integrated housing 22.

[0060] The pressure cores 8 in area seven are located in chambers of type B and C, respectively, to measure their pressures.

[0061] like Figure 4 、 Figure 5As shown, the integrated housing 22 and pump front cover 10 are designed using additive manufacturing techniques. During the component design process, a certain wall thickness is maintained between the connection structure and the outer wall, between different pressure chambers, and between the internal chamber and the exterior. Only the sealing structure, connection structure, and areas necessary for strength are retained. A flow channel reversal arc transition design reduces flow resistance. By sharing the outer wall of the flow channel and the outer wall of the structure, the integrated component structure is formed, minimizing the component's physical footprint, while ensuring functional performance and achieving the lowest weight.

[0062] During the forming process of the pump front end cover 10 and the integrated shell 22, the internal flow channels are self-formed, and there are no additional process flow channels and process plugging holes. The sealing structure and the connection structure retain a small amount of secondary processing allowance, and the dimensional accuracy is guaranteed by secondary machining. The rest is directly formed into place by additive manufacturing. The main structure is formed quickly and less material is removed during secondary processing.

[0063] The above-described embodiments are only preferred specific implementations of the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. An integrated electrostatic actuator, characterized in that: It includes an actuator, an oil-immersed motor pump, an integrated housing (22), a pump front end cover (10), an oil tank (12), a filling valve (11), a bypass valve (7), an oil replenishment check valve and a motor rear end cover (18); The integrated housing (22) includes six areas, area one is located at the central axis of the integrated housing, area two is located below area one, and the remaining areas are located above area one; area one is a cylindrical structure, the inner cavity of which is equipped with an actuator cylinder; area two is a cylindrical structure, the inner cavity of which is equipped with an oil-immersed motor pump; area three is equipped with a filling valve (11) and an oil replenishing one-way valve; area four is equipped with an oil tank (12) and an oil replenishing one-way valve; area five is equipped with a sealing connector; area six is ​​equipped with a bypass valve (7); At the end of region 2, the inner cavity branches into three flow channels. The center is the first flow channel, flanked by the second and third flow channels. The first flow channel extends along the inner cavity of region 2, passes through region 2, and then extends to regions 3 and 4 in sequence, forming a hydraulic chamber A. The oil output from the bellows oil tank 12 flows into the chamber. A fourth flow channel and a fifth flow channel are provided at the outer edge of the end of region 2 and extend along the side of region 2 opposite to region 1, respectively. The other ends of the flow channels are connected to the two ends of the actuator in region 1 respectively. The pump front end cover (10) is installed on the end of the area 2. The pump front end cover (10) is provided with five flow channel openings, respectively connecting the first flow channel to the fifth flow channel; a connecting pipe is provided on the lower surface of the pump front end cover, connecting the second flow channel with the fourth flow channel, and connecting the third flow channel with the fifth flow channel; wherein the second flow channel and the fourth flow channel form a hydraulic chamber B, and the third flow channel and the fifth flow channel form a hydraulic chamber C; The bypass valve (7) connects the hydraulic chamber A, the hydraulic chamber B and the hydraulic chamber C.

2. The integrated electrostatic actuator according to claim 1, characterized in that: The actuator is a single-rod symmetrical cylinder design, comprising a piston rod (1), a middle rod (2), an actuator front end cover (3), a front support lug (5), a rear support lug (4) and a feedback potentiometer (19); The front end cover (3) of the actuator is installed at the front of the area 1. An arc-shaped pipeline is provided inside the front end cover (3) of the actuator to connect the fourth flow channel and the fifth flow channel, so as to communicate the two oil inlet and outlet ports on the end face of the oil-immersed motor pump with the inner cavity of the actuator. The piston rod (1) is unilaterally extended, and the inner side and outer side of the piston rod are respectively connected to the fourth flow channel and the fifth flow channel; The body of the feedback potentiometer (19) is fixed on the integrated housing (22) by means of a rear support lug (4), and the movable part is fixed on the piston rod (1) by means of a front support lug (5).

3. The integrated electrostatic actuator according to claim 1, characterized in that: The oil-immersed motor pump comprises a motor, a plunger pump (9), a motor rear end cover (18), and a distribution plate (20); The distribution plate (20) is located at the end of the second area, dividing the inner cavity of the second area into three flow channels, namely the first flow channel, the second flow channel and the third flow channel; The plunger pump (9) and the valve plate (20) are mechanically matched and sealed, and a gap exists; when the oil pressure in any hydraulic chamber is high, the oil will leak into the other two hydraulic chambers through the gap; The motor is located at the output side of the plunger pump, and the rear end cover (18) of the motor is installed at the other end of the area 2; The pump front end cover (10) is installed on two end portions of the area where the distribution plate (20) is located.

4. The integrated electrostatic actuator according to claim 1 or 3, characterized in that: The second area is a cylindrical structure with a small front end and a large rear end. The plunger pump (9) has a smaller outer diameter than the motor. The plunger pump (9) is placed at the front end of the inner cavity of the second area, and the motor is placed at the rear end of the inner cavity of the second area.

5. The integrated electrostatic actuator according to claim 1, characterized in that: An arc-shaped groove is provided at the rear end of the area one, connecting the first flow channel and the area five, and the output wires of the motor stator (16) and the rotary transformer (6) are led to the sealing connector (21) through the arc-shaped groove.

6. The integrated electrostatic actuator according to claim 1, characterized in that: The integrated housing (22) and the pump front cover (10) are both designed based on an additive manufacturing process, with the internal flow channel self-forming, and all the components of the actuator are installed on the 3D printed integrated housing (22).

7. The integrated electrostatic actuator according to claim 1, characterized in that: The oil in the filling valve (11) enters the hydraulic chamber C through the oil replenishment one-way valve, and the oil in the bellows oil tank (12) enters the hydraulic chamber B through the oil replenishment one-way valve.

8. The integrated electrostatic actuator according to claim 1, characterized in that: Each flow channel adopts an arc transition design at the reversing point to reduce flow resistance.

9. The integrated electrostatic actuator according to claim 1, characterized in that: The integrated shell (22) is further provided with a region seven, which is located above the region two and between the region four and the region five; the region seven is an elliptical column structure, and the inner cavity is provided with a pressure core (8).

10. The integrated electrostatic actuator according to claim 1, characterized in that: The integrated housing (22) is further provided with an area eight, which is located above the area two and between the area four and the area five; the area eight is a cylindrical structure, the inner cavity of which is equipped with a safety valve (15) connected to the hydraulic chamber A; when the oil pressure in the hydraulic chamber A exceeds a set safety value, the oil is discharged from the safety valve.

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