A rotary drive driven by SMA wires

Abstract

The application provides a SMA wire driven rotary driver, the square head section at both ends of the output shaft is connected with the fixed end, the middle circular shaft section is provided with a torsion disc and a driving disc, the driving disc is fixedly connected with the output shaft, and the transmission torsion disc is supported on the output shaft through a bearing. The SMA wire is arranged in a folded-back mode or a parallel mode through the axial holes in the transmission torsion disc and the driving disc, the outer edge of the transmission torsion disc is fixedly connected with the transmission torsion shell and the driving end to output the torque. When the driver is subjected to an external load, the transmission torsion shell rotates relative to the output shaft, the transmission torsion disc rotates relative to the driving disc, and the driver is balanced under the action of the external load and the tension of the SMA wire. When driving is needed, the SMA wire is heated by power supply to generate phase change and shrink, the transmission torsion disc is driven to rotate, and the relative rotation between the driving end and the fixed end is realized. After the driving is finished, the SMA wire is powered off and cooled, and the driver returns to the state before driving under the action of the external load. The driver has the advantages of simple structure, small radial size, large output torque, high driving efficiency and the like.

Description

Technical Field

[0001] This invention relates to the field of spacecraft drive technology, and in particular to a rotary drive device. Background Technology

[0002] As a power source for realizing mechanical actions, rotary actuators are widely used in many fields such as machinery, electronics, and chemical industry. The fields of aircraft, automobiles, robots, and spacecraft have put forward new requirements for the rotary actuators required. The rotary actuators used in these scenarios are different from conventional actuators and need to meet the following requirements: (1) The actuator has a limited working stroke and only needs to rotate a limited angle when driving; (2) The actuator is highly miniaturized and integrated, with small size, light weight, high power density, and controllable cost; (3) The actuator has a large output torque. The miniaturized actuator has a short output lever arm and requires the actuator to output a large torque when driving the load.

[0003] Rotary actuators are widely used in spacecraft. The most typical type is the SMA-driven rotary actuator. There are two main types of high-torque SMA actuators: one type uses an SMA tube as the driving element. This type of actuator has a small driving stroke and a complex structure. The other type is the SMA wire-spring drive. This type of actuator has a large output stroke but a small output torque, which limits its use. Summary of the Invention

[0004] To address the shortcomings of existing rotary actuators, this invention proposes a rotary actuator using SMA wires for driving. This actuator has a simple structure, small radial dimensions, and large output torque.

[0005] The technical solution adopted in this invention is as follows: a rotary actuator driven by SMA wire, which mainly includes SMA wire, output shaft, left transmission disk, right transmission disk, drive disk, transmission housing and bearing. The SMA wire is the driving element, and the output shaft and the two transmission disks are connecting parts.

[0006] The output shaft is connected to the fixed end at both ends. The middle circular shaft section supports two transmission disks (left and right) via bearings near both ends. The left and right transmission disks have identical structures, generally ring-shaped, with their centers mate with the bearings. Several axial holes for inserting SMA wires are evenly distributed around the circumference of each transmission disk. The outer edge of the transmission disk is fixed to the transmission housing, and the drive end is connected to the outside of the transmission housing. The middle of the output shaft circular shaft section is fixed to the drive disk, which has axial holes corresponding to the axial holes of the transmission disks. The SMA wires are arranged axially, sequentially passing through the axial holes on the left transmission disk, drive disk, and right transmission disk, with both ends of the wire fixed to the outside of either the left or right transmission disk.

[0007] When subjected to an external load, the torque transmission housing rotates relative to the output shaft; correspondingly, the left and right torque transmission discs rotate at a certain angle relative to the drive disc; the entire actuator remains balanced under the external load and the tension of the SMA wire. When driving is required, the SMA wire is energized, causing its temperature to rise, resulting in phase change deformation and contraction, driving the torque transmission disc to rotate, thereby achieving relative rotation between the drive end and the fixed end. After driving is completed, the energization of the SMA wire is stopped, the SMA wire temperature decreases, and the actuator returns to its state before driving under the external load.

[0008] Furthermore, the output shaft is provided with 6 annular grooves, the positions of which correspond to the front and rear edges of the left and right transmission disks and drive disks. A limit structure is fixed in the grooves to axially limit the transmission disks and drive disks.

[0009] Furthermore, the drive disk and the output shaft are keyway-fitted, and the drive disk and the output shaft are circumferentially locked.

[0010] Furthermore, the bearing between the torque transmission disc and the output shaft is a rolling bearing or a sliding bearing, which allows the torque transmission disc to rotate freely on the output shaft. Under external load or SMA wire tension, the torque transmission disc and the output shaft can rotate relative to each other.

[0011] Furthermore, the left and right transmission discs have one or more radial threaded holes distributed on their rims, which can be connected to the transmission housing and drive end by bolts to output torque.

[0012] Furthermore, the two ends of the transmission housing are connected to end caps, and the end caps are provided with axial small holes. Wires for connecting to an external power source are inserted through the holes to supply power to the SMA wire.

[0013] Furthermore, insulating tubes are provided in the axial circular holes on the transmission disc and the drive disc, and SMA wires are arranged through the insulating tubes to ensure that the SMA wires are electrically insulated from the transmission disc and the drive disc.

[0014] Furthermore, the portion of the SMA wire located between the drive disc and the transmission disc is covered with heat-shrink tubing or other insulating high-temperature resistant materials, which can electrically insulate the entire SMA wire from the metal structural components inside the driver.

[0015] Furthermore, in order to obtain greater output torque, the driver needs to arrange the longest possible SMA wire within a limited space. To this end, the present invention can arrange the SMA wire in either a single wire folded-back arrangement or multiple wires arranged in parallel. When the folded-back arrangement is used, the SMA wire passes through an insulating bend at the fold. When the parallel arrangement is used, multiple SMA wires are arranged in parallel and driven simultaneously, achieving a redundant design for the driver.

[0016] Compared with existing technologies, this invention has the advantages of small radial dimension, large output torque, and low energy loss, specifically in the following aspects:

[0017] (1) The SMA wires of the present invention are arranged along the axial direction, which greatly reduces the radial space required for arranging the SMA wires. This design greatly reduces the radial dimension of the driver.

[0018] (2) The present invention has multiple axial circular holes on the circumference of the transmission disk and the drive disk, which can be arranged by folding back a single SMA wire or arranging multiple SMA wires in parallel as needed. Under the premise that the axial dimension of the driver remains unchanged, a larger output torque can be obtained.

[0019] (3) The SMA wire of the present invention is provided with an insulation device along the entire path of the arrangement, which can effectively prevent the SMA wire from contacting or entangled with other structures during the driving process, resulting in low internal friction loss and high driving efficiency. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the external structure of the present invention;

[0021] Figure 2 This is a schematic diagram of the internal structure of the present invention;

[0022] Figure 3 This is a schematic diagram of the output shaft of the present invention;

[0023] Figure 4 This is a schematic diagram of the structure of the transmission disc of the present invention;

[0024] Figure 5 This is a schematic diagram of the drive disk of the present invention;

[0025] Figure 6 This is a schematic diagram of the structure of the torsion transmission shell of the present invention.

[0026] The markings in the diagram represent: 1. Output shaft; 2. Torque housing; 3. End cap; 4. SMA wire; 5. Left torque plate; 6. Drive plate; 7. Right torque plate; 8. Bearing; 9. Snap ring; 10. Key; 11. Insulating tube; 12. Insulating bend; 13. Wire fixing head. Detailed Implementation

[0027] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0028] like Figure 1 , 2As shown, the present invention provides a rotary actuator driven by an SMA wire. The actuator uses an output shaft 1 and a transmission disk as connecting parts. The two ends of the output shaft 1 are fixedly connected to the fixed end, and the middle part is fixedly connected to the drive disk 6. The transmission disk includes a left transmission disk 5 and a right transmission disk 7, which are supported on the output shaft 1 by bearings 8. The cylindrical transmission housing 2 is fixedly connected to the left transmission disk 5 and the right transmission disk 7 by bolts. The transmission housing 2 is connected to the drive end, and its two ends are connected to end caps 3. The drive element SMA wire 4 is arranged to pass through the left transmission disk 5, the drive disk 6 and the right transmission disk 7.

[0029] The structure of output shaft 1 is as follows Figure 3 As shown, its left and right ends are square-headed sections, which can be easily and efficiently connected to the fixed end; the middle part is a round shaft section, and the center of the round shaft section has an axial groove for cooperating with the key 10 to fix the drive disk 6; the left and right ends of the round shaft section are connected to the left transmission torque disk 5 and the right transmission torque disk 7 through bearings 8. The drive disk 6, the left transmission torque disk 5 and the right transmission torque disk 7 are all axially limited by retaining rings 9, which are fixed in 6 annular grooves on the output shaft 1.

[0030] The left-hand transfer disk 5 and the right-hand transfer disk 7 of this invention have the same structure. Taking the left-hand transfer disk 5 as an example, it is as follows: Figure 4 As shown, the overall shape is ring-shaped, and the large circular hole 501 in the center can be matched with the bearing 8; several axial circular holes 502 are distributed on the circumference of the transmission disc for installing the insulating tube 11. The spacing angle between adjacent circular holes 502 is the same, and an insulating bend 12 is provided at the interval; the edge of the transmission disc is provided with a radial threaded hole 503 for connecting the transmission disc and the transmission housing 2.

[0031] The SMA wire 4 passes axially through the insulating tubes 11 on the left transmission disk 5, the drive disk 6, and the right transmission disk 7. Both ends of the wire are fixed to the outside of the left or right transmission disk 5 or 7 via wire fixing heads 13. The folded-back portion of the SMA wire 4 passes through the insulating bend 12. In this example, both the insulating tubes 11 and 12 are made of ceramic material, which not only ensures electrical insulation between the SMA wire 4 and the two transmission disks and the drive disk 6, but also effectively reduces friction between the SMA wire 4 and other components during the phase change driving process.

[0032] The structure of the drive disk 6 of this invention is as follows: Figure 5 As shown, the drive disk 6 has a central hole with an axial groove, and the output shaft 1 also has an axial groove at the corresponding position. The key 10 can lock the drive disk 6 and the output shaft 1 circumferentially. The drive disk 6 has an axial circular hole on its edge that corresponds to the circular hole 502 of the left transmission disc 5, which is used to fix the insulating tube 11.

[0033] The torsion transmission outer shell 2 of the present invention has a cylindrical structure, the specific structure of which is as follows: Figure 6As shown, the cylinder wall of the transmission housing 2 is provided with multiple rows of holes evenly distributed around the circumference. The round holes in the middle are used to bolt to the left transmission disk 5 and the right transmission disk 7, and the round holes at the ends are used to bolt to the end cover 3.

[0034] The working process of the driver of this invention is as follows:

[0035] Before driving, under the action of external load, the transmission housing 2 rotates relative to the output shaft 1; correspondingly, the left transmission disk 5 and the right transmission disk 7 rotate at a certain angle relative to the drive disk 6; the driver is balanced under the action of external load and the tension provided by SMA wire 4.

[0036] When driving is required, the SMA wire 4 is energized, causing it to undergo a phase change and shrink due to heat, which drives the left torsion disk 5 and the right torsion disk 7 to rotate relative to the drive disk 6, thereby achieving relative rotation between the fixed end and the drive end.

[0037] After the drive is completed, the power supply to SMA wire 4 is stopped, SMA wire 4 cools down, and the driver returns to its state before the drive under the action of external load.

[0038] The above description is merely an embodiment of the present invention and is not intended to limit the present invention in any way. Techniques not described in detail herein are well-known in the art. Any modifications, equivalent variations, alterations, or improvements made to the above embodiments based on the principles and technical essence of the present invention should be included within the scope of protection of the present invention.

Claims

1. A rotary actuator driven by an SMA wire, comprising an output shaft (1), a torque transmission housing (2), an SMA wire (4), a left torsion disc (5), a drive disc (6), a right torsion disc (7), and a bearing (8); characterized in that, The output shaft (1) and the transmission disks (5,7) are connecting parts; the two ends of the output shaft (1) are connected to the fixed end, and the middle circular shaft section supports the left transmission disk (5) and the right transmission disk (7) respectively through bearings (8) at both ends. The middle of the circular shaft section of the output shaft (1) is fixedly connected to the drive disk (6); the outer edge of the transmission disks (5,7) is fixedly connected to the transmission housing (2), and the drive end is connected to the outside of the transmission housing (2); the transmission disks (5,7) and the drive disk (6) are provided with axial circular holes for passing through SMA wires (4); The SMA wire (4) is a driving element, which is arranged to pass through the axial circular holes on the left transmission disc (5), the driving disc (6) and the right transmission disc (7) along the axial direction. When subjected to external load, the transmission housing (2) rotates relative to the output shaft (1), and the left transmission disk (5) and right transmission disk (7) rotate relative to the drive disk (6). The entire driver remains balanced under the action of external load and the tension of SMA wire (4). When driving is required, the SMA wire (4) is heated by electricity, causing it to undergo phase change deformation and shrink, driving the transmission disks (5,7) to rotate, thereby realizing the relative rotation between the drive end and the fixed end. After the driving is completed, the power supply to the SMA wire (4) is stopped, the temperature of the SMA wire (4) decreases, and the driver returns to the state before driving under the action of external load.

2. The SMA wire driven rotary actuator according to claim 1, characterized in that, The portions of the output shaft (1) that connect to the fixed ends are square-headed sections.

3. The SMA wire driven rotary actuator according to claim 1, characterized in that, The output shaft (1) is provided with 6 annular grooves, the positions of which correspond to the front and rear edges of the left transmission disc (5), the right transmission disc (7) and the drive disc (6), respectively. The grooves are fixed with retaining rings (9) to axially limit the transmission discs (5,7) and the drive disc (6).

4. The SMA wire driven rotary actuator according to claim 3, characterized in that, The drive disk (6) and the output shaft (1) are keyway fitted together, and the drive disk (6) and the output shaft (1) are circumferentially locked.

5. The SMA wire driven rotary actuator according to claim 1, characterized in that, The bearing (8) is a rolling bearing or a sliding bearing.

6. The SMA wire driven rotary actuator according to any one of claims 1 to 5, characterized in that, The driver also includes an end cap (3), which is connected to both ends of the torque transmission housing (2). The end cap (3) has an axial small hole through which a wire for powering the SMA wire (4) is inserted.

7. The SMA filament driven rotary actuator according to claim 1, characterized in that, Insulating tubes (11) are provided in the axial circular holes on the transmission disc (5,7) and the drive disc (6), and SMA wires (4) are arranged through the insulating tubes (11).

8. The SMA filament driven rotary actuator according to claim 1 or 7, characterized in that, The portion of the SMA wire (4) between the transmission disc (5,7) and the drive disc (6) is fitted with a heat-shrink tubing, which electrically insulates the entire SMA wire (4) from the metal structure inside the driver.

9. The SMA wire driven rotary actuator according to claim 1, characterized in that, The SMA wire (4) is arranged in either a single wire folded-back arrangement or multiple wires arranged in parallel. When the folded-back arrangement is used, the SMA wire (4) passes through the insulating bend (12) at the fold. When the parallel arrangement is used, multiple SMA wires (4) are arranged in parallel and driven simultaneously.

10. The SMA filament driven rotary actuator according to claim 7 or 9, characterized in that, Both the insulating tube (11) and the insulating bend (12) are made of ceramic material.

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