SMA WIRE-DRIVEN REUSABLE RELEASE MECHANISM HAVING SELF-RESETTING FUNCTION

Abstract

The present invention discloses an SMA wire-driven reusable release mechanism having a self-resetting function. The present invention adopts a structure of two-stage load reduction and one-stage release. First-stage load reduction: a compression rod and a hoop petal, as well as an inclined block and a shell or a sliding block, all cooperate with each other by means of inclined surfaces, which can transfer most of tension load of the compression rod to the shell, leaving only a small part of the load transmitted to a thrust bearing. Second-state load reduction: balls in the thrust bearing are coated with a molybdenum disulfide lubricating coating, which can effectively reduce friction so as to reduce a torque transmitted to a driving shaft. First-stage release: the driving shaft drives a thrust bearing to rotate by a certain angle, causing an upper ring of the thrust bearing to descend to release a certain axial clearance.

Claims

1. An SMA wire-driven reusable release mechanism having a self-resetting function, internally and sequentially comprising an SMA driver assembly, a thrust bearing assembly, a tray assembly, and a separation assembly from bottom to top, and realizing external encapsulating by a shell (1) and a bottom cover (22), wherein the SMA driver assembly comprises an SMA wire (13), a driving shaft (12), a reset spring (11), and a support frame (14); the driving shaft (12) is mounted on the support frame (14); the SMA wire (13) is wrapped around the driving shaft (12) and two ends are fixed to the support frame (14); the reset spring (11) is mounted on a tray nut (10), and the other end is mounted on the driving shaft (12); the thrust bearing assembly is pressed onto the support frame (14) and connected to the driving shaft (12); pits are uniformly formed in a raceway of the thrust bearing assembly; the tray assembly comprises a tray (6), a tray spring (7), a tray shaft (8), a tray bracket (9), and the tray nut (10), wherein the tray bracket (9) is mounted on the support frame (14); the tray (6) is mounted on the tray bracket (9) through the tray shaft (8) and the tray nut (10); the tray spring (7) is wrapped around the tray shaft (8) and located between the tray (6) and the tray bracket (9); the separation assembly comprises a compression rod (2), a hoop petal (3), and an inclined block (4), wherein a protrusion is arranged at one end of the compression rod (2), and the protrusion of the compression rod (2) is inserted into the hoop petal (3) and surrounded by the hoop petal (3); the upper end and the lower end of the hoop petal (3) are respectively in contact with the shell (1) and the tray (6); the inclined block (4) is located between the hoop petal (3) and the shell (1) and moves up and down along an inclined surface; and the hoop petal (3) and the inclined block (4) are provided with symmetrical grooves in a contact surface.

2. The SMA wire-driven reusable release mechanism having a self-resetting function according to claim 1, wherein the thrust bearing assembly is of a double-column structure, and sequentially comprises an upper ring (15), an upper row of balls (16), an upper cage (17), a middle ring (18), a lower cage (19), a lower row of balls (20), and a lower ring (21) from top to bottom, wherein the lower ring (21) of a thrust bearing is pressed onto the support frame (14), and the middle ring (18) is connected to the driving shaft (12); and pits are formed in a raceway of the middle ring (18) and are evenly spaced from the raceway.

3. The SMA wire-driven reusable release mechanism having a self-resetting function according to claim 1, wherein the balls in the thrust bearing assembly are coated with a molybdenum disulfide lubricating coating.

4. The SMA wire-driven reusable release mechanism having a self-resetting function according to claim 1, wherein the top of the shell (1) is narrow in an upper portion and wide in a lower portion, a side surface is inclined, and the shell cooperates with an inclined surface of the inclined block (4); and the inclined block (4) slides up and down along the side surface of the shell (1).

5. The SMA wire-driven reusable release mechanism having a self-resetting function according to claim 1, wherein the separation assembly further comprises a sliding block (5), the sliding block (5) is mounted on an upper end surface of the thrust bearing assembly, the sliding block (5) is provided with an inclined surface which cooperates with the inclined block (4), and the inclined block (4) slides up and down along the inclined surface of the sliding block (5).

6. The SMA wire-driven reusable release mechanism having a self-resetting function according to claim 5, wherein the sliding block (5) is conical, and the inclined surface of the inclined block (4) is formed at the bottom of the inclined block (4) and cooperates with the sliding block (5).

7. The SMA wire-driven reusable release mechanism having a self-resetting function according to claim 5, wherein the sliding block (5) penetrates through the inclined block (4).

8. The SMA wire-driven reusable release mechanism having a self-resetting function according to claim 1, wherein two groups of SMA driver assemblies are arranged.

9. The SMA wire-driven reusable release mechanism having a self-resetting function according to claim 1, wherein a circular hole is formed in a center of the bottom of the bottom cover (22), and an inner hexagonal groove is formed in the bottom of the driving shaft (12) for manual rotation of the driving shaft (12).

10. The SMA wire-driven reusable release mechanism having a self-resetting function according to claim 1, wherein a protrusion is processed on a side surface of the thrust bearing assembly, and corresponding grooves are formed in the side surface of the bottom cover (22) for manual unlocking and resetting.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG. 1 shows a schematic structural diagram of the existing SMA wire-driven connection and unlocking mechanism;

[0031] FIG. 2 shows a schematic diagram of a state of a release mechanism of the present invention, where (a) is in a locking state and (b) is in an unlocking process state;

[0032] FIG. 3 shows a schematic structural diagram of the release mechanism of the present invention;

[0033] FIG. 4 shows a schematic structural diagram of a thrust bearing assembly, where (a) is in a locking state and (b) is in an unlocking process state;

[0034] FIG. 5 shows a schematic structural diagram of deep and shallow grooves in a middle ring of a thrust bearing;

[0035] FIG. 6 shows a schematic structural diagram of an SMA driver assembly;

[0036] FIG. 7 shows a schematic diagram of mounting of a driving shaft and a support frame;

[0037] FIG. 8 shows a schematic diagram of a manual unlocking structure of a driving shaft and a shell;

[0038] FIG. 9 shows an alternative scheme 1 for a separation assembly;

[0039] FIG. 10 shows an alternative scheme 2 for a separation assembly;

[0040] FIG. 11 shows an alternative scheme 3 for a separation assembly;

[0041] FIG. 12 shows a scheme of replacing a plug enclasping connection with a threaded connection; and

[0042] FIG. 13 shows an alternative scheme for mounting of an SMA wire.

[0043] Where, 1-shell; 2-compression rod; 3-hoop petal; 4-inclined block; 5-sliding block; 6-tray; 7-tray spring; 8-tray shaft; 9-tray bracket; 10-tray nut; 11-reset spring; 12-driving shaft; 13-SMA wire; 14-support frame; 15-upper ring of thrust bearing; 16-upper row of balls; 17-upper cage; 18-middle ring of thrust bearing; 19-lower cage; 20-lower row of balls; 21-lower ring of thrust bearing; 22-bottom cover.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0044] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0045] The specific structure of the present invention is shown in FIG. 3, and a releaser can be divided into four assemblies: an SMA driver assembly, a thrust bearing assembly, a tray assembly, and a separation assembly. Where, the SMA driver assembly consists of the SMA wire 13, the support frame 14, the driving shaft 12, and the reset spring 11, the thrust bearing assembly consists of an upper ring 15 of a thrust bearing, an upper row of balls 16, an upper cage 17, a middle ring 18 of the thrust bearing, a lower cage 19, a lower row of balls 20, and a lower ring 21 of the thrust bearing; the tray assembly consists of a tray 6, a tray spring 7, a tray shaft 8, a tray bracket 9, and a tray nut 10; the separation assembly consists of a compression rod 2, a hoop petal 3, an inclined block 4, and a sliding block 5; and the outer part of the mechanism is enclosed by a shell 1 and a bottom cover 22.

[0046] As shown in FIG. 3, the SMA wire 13 goes around the driving shaft 12 which is assembled in the groove of the support frame and can rotate by a certain angle. The support frame 14 is assembled on the bottom cover 22. Besides, the structure of the thrust bearing is shown as FIG. 4, and the thrust bearing consists of the upper ring 15 of the thrust bearing, the upper row of balls 16, the upper cage 17, the middle ring 18 of the thrust bearing, the balls 21, the lower cage 22, and the lower ring 21 from top to bottom; and the lower ring of the thrust bearing is pressed onto the support frame 14, and the driving shaft 12 is connected to the middle ring 18 of the thrust bearing, which can drive the middle ring of the thrust bearing to rotate. At the same time, the tray bracket 9 is also mounted on support frame 14 through screws, the tray shaft 8 is mounted on the tray bracket 9 through the tray nut 10, the reset spring 11 is mounted on tray nut 10, and the other end is mounted on driving shaft 12 for resetting the driving shaft 12. One end of the tray spring 7 is pressed onto the tray bracket 9, and the other end is pressed onto the tray 6. The separation assembly is mounted on the upper ring 15 of the thrust bearing.

[0047] The locking state of a self-resetting releaser is shown as FIG. 2 (a). When unlocking is needed, the SMA wire 13 is electrified for heating, such that the SMA wire 13 contracts to drive the driving shaft 12 to rotate, and the driving shaft 12 drives the middle ring 18 of the thrust bearing to rotate. The upper row of balls 16 and the lower row of balls 20 fall into the deep groove 18-I of the middle ring 18 of the thrust bearing, and the upper ring 15 of the thrust bearing descends by a certain displacement, as shown in FIG. 2 (b). Then, the sliding block 5 descends by a certain displacement under the pressure of the inclined block 4, and the inclined block 4 moves radially outwards under the action of the hoop petal 3. The constraint of the hoop petal 3 on the compression rod 2 is released, and the compression rod 2 is separated under tension. After the SMA wire 13 cools, the tension of the SMA wire decreases. Under the action of the reset spring 11, the driving shaft 12 resets, and at the same time, the middle ring 17 of the thrust bearing is driven to reset. The upper row of balls 16 and the lower row of balls 20 move from the deep groove 18-I of the middle ring 17 of the thrust bearing to the shallow groove 18-II. The upper ring 15 of the thrust bearing moves upwards along with the upper row of balls and the lower row of balls, and the sliding block 5 moves upwards accordingly. The inclined block 4 moves radially inwards, and the hoop petal 3 resets.

[0048] The process of locking the compression rod of the self-resetting releaser is a reverse process of the unlocking process, as shown in FIG. 2 (b) to FIG. 2 (a). The compression rod 2 is inserted into the mechanism, and under the action of the compression rod 2, the hoop petal 3 moves downwards along with the compression rod 2, while the tray spring 7 is compressed through the tray 6. Due to the cooperation of the grooves, the radial constraint of the inclined block 4 on the hoop petal 3 disappears, and the hoop petal 3 moves to two sides. The pressure of the compression rod 2 on the hoop petal 3 disappears. Under the action of the tray 6, the hoop petal 3 moves upwards and inwards simultaneously, the compression rod 2 is enclasped, thereby achieving locking.

[0049] As shown in FIG. 4 and FIG. 5, the present invention draws on the structure of the thrust bearing and improves a ball groove of the middle ring 18 of the thrust bearing into a structure where the deep groove 18-I and the shallow groove 18-II are staggered. The shallow groove can be an original rolling groove, while the deep groove is designed as the pits. When releasing is needed, the middle ring of the thrust bearing rotates by a certain angle under the action of the driving shaft. The upper row of balls 16 and the lower row of balls 20 roll into the deep groove 18-I from the shallow groove 18-II, thereby achieving the release of axial clearance. During automatic resetting, the driving shaft 12 drives the inner ring 18 of the thrust bearing to rotate back to a certain angle. Under the action of the upper cage 17, the balls roll from the deep groove 18-I of the middle ring 18 of the thrust bearing to the shallow groove 18-II, thereby eliminating axial clearance.

[0050] As shown in FIG. 6 and FIG. 7, the SMA driver assembly consists of the reset spring 11, the driving shaft 12, the SMA wire 13, and the support frame 14. Two ends of two sets of SMA wires 13 are fixed to the support frame and go around the driving shaft 12. The driving shaft 12 is assembled in the groove of the support frame and can rotate by a certain angle.

[0051] As shown in FIG. 8, a circular hole is formed in the center of the bottom of the bottom cover 15, and an inner hexagonal groove is formed in the bottom of the driving shaft 12. The driving shaft 12 can be manually rotated by means of an internal hexagonal wrench, thereby achieving manual unlocking and resetting.

[0052] Apparently, the embodiments described are merely a part rather than all of the embodiments of the present invention. The SMA driver assembly, the thrust bearing assembly, the tray assembly, and the separation assembly all have alternative schemes.

[0053] Taking the separation assembly as an example, three alternative schemes can be proposed. Scheme 1 is shown as FIG. 9, the inclined block 4 and the sliding block 5 are combined into one part, and the shell with the inclined surface is adopted to cooperate with the inclined block, thereby achieving the release of radial constraint in the inclined direction of the inclined block. Scheme 2 is shown as FIG. 10, the sliding block 5 is conical, and the inclined block 4 is changed into four cylindrical sliding blocks. The conical sliding block 5 moves downwards, and the cylindrical sliding block 4 moves outwards to release the hoop petal 3. Scheme 3 is shown as FIG. 11, the sliding block 5 penetrates through the inner part of the inclined block 4, and the inclined surface in the inclined block 4 cooperates with that of the sliding block 5. When the sliding block 5 moves downwards, the inclined block 4 moves outwards to release the hoop petal 3. It should be noted that the above multiple alternative manners are not all implementation examples. Schemes that can be easily thought of by designers in the prior art, such as changing the shape and size of the inclined block and the sliding block, or integrally combining the two parts, should all be within the scope of protection of the present invention.

[0054] The compression rod 2 and a separation structure of the present invention adopt a pluggable connection manner which can be replaced with a threaded connection, as shown in FIG. 12. A mounting manner of the SMA wire of the SMA driver assembly in the present invention is not unique and can be replaced with the mounting manner as shown in FIG. 13. The above changes should also be within the scope of protection of the present invention.

[0055] To sum up, the above only describes preferred embodiments of the present invention and is not intended to limit the protection scope thereof. Any modifications, equivalent replacements, improvements, and the like made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.