Large-load bidirectional driver

Abstract

The invention provides a large-load two-way driver. The large-load two-way driver comprises a shell, two SMA wire-spring structures, a taper pin, a retraction spring, a locking sliding block, a steel ball and a double-slope wedge block. A first set of SMA-spring structure for driving the locking sliding block is arranged in a rectangular cavity of the shell, and a taper pin and a second set of SMA-spring structure for driving the double-bevel wedge block are arranged in an L-shaped cavity; when the taper pin needs to stretch out, the first set of SMA-spring structure is powered on to drive the locking sliding block to move rightwards and release limiting on the steel ball, the compression spring of the second set of SMA-spring structure pushes the double-inclined-face wedge block to move leftwards, and then the taper pin is driven to be ejected out and kept in the stretching-out state through friction self-locking of the inclined faces. When the taper pin needs to retract, the second SMA-spring structure is powered on, the double-bevel wedge block is driven to move rightwards, the retraction spring pulls back the taper pin, meanwhile, the steel ball limits the double-bevel wedge block again, and the taper pin is stabilized in the retraction state. The invention has the advantages of simple and compact structure, light weight, strong bearing capacity and high driving reliability.

Description

Technical Field

[0001] The present invention relates to the technical field of locking devices, and particularly relates to a locking device capable of realizing bidirectional driving. Background Art

[0002] After the space deployment mechanism of a spacecraft is deployed in orbit, a locking device is required to lock its deployed state; when the spacecraft makes a maneuvering orbit change, the deployment mechanism needs to be retracted. At this time, the locking device first releases the lock, and after the deployment mechanism is retracted in place, its retracted state needs to be locked and limited; after the orbit change is completed, the deployment mechanism needs to be deployed again, and the locking device locks the deployed state again. This requires the locking device to have bidirectional driving ability and provide two stable states: a locked position and an unlocked position.

[0003] In the prior art, the utility model patent CN214729790U provides a shape memory metal bidirectional driver (as Figure 1 shown), which uses two oppositely pulled shape memory alloy wires (SMA wires) to directly drive the movement of a sliding pin with two trapezoidal grooves, realizes bidirectional driving, and completes the switching between two states of the sliding pin extending and retracting, so as to output two working states of a locked position and an unlocked position externally. Although this driver can realize the bidirectional driving function, its load-bearing capacity is limited. When the sliding pin is in the extended state, if it is compressed by too large an external force, the inclined surface of the trapezoidal groove will squeeze the steel ball out again, and then the sliding pin will lose its restraint and retract into the cage. Therefore, it is difficult for the sliding pin of this driver to maintain a stable extended state when bearing a large load. In addition, during the extension process of the sliding pin, the driving force generated by the energization and contraction of the SMA wire is completely relied on to push out the sliding pin, and the pushing force is small, and it cannot be used for large deployable structures with a large demand for pushing force.

[0004] The patent application CN101435452A provides a tightening device driven by a shape memory alloy (as Figure 2 shown), which uses two sets of SMA-spring drivers to actuate at intervals, and the second SMA-spring structure is used to lock the first SMA-spring structure. The first SMA-spring structure pushes the elastic claw to move upward through a double-wedge surface structure to output a tightening force. By energizing the two sets of SMA-spring structures respectively, the elastic claw can be controlled to complete the tightening of the structural member or the retraction to release the restraint. This tightening device has a complex structure and limited driving reliability. In particular, the first wedge block driven by the first SMA-spring structure limits the retraction position of the second wedge block by inserting a cylindrical boss into the sliding groove of the second wedge block. The contact surface between the cylindrical boss and the sliding groove is large, and the frictional resistance is large. When the first SMA contracts and pulls up the first wedge block, it not only needs to overcome the spring force of the first spring, but also needs to overcome the above frictional resistance, and it is easy to have a situation of driving failure and inability to release the restraint of the contracted state. Summary of the Invention

[0005] In order to overcome the shortcomings of the above-mentioned bidirectional actuators such as low load-bearing capacity, limited reliability and complex structure, the present invention proposes a large-load SMA bidirectional actuator with simple structure, high reliability, and combined friction self-locking and spring tightening.

[0006] The technical solution adopted by the present invention is: a large-load bidirectional driver, which comprises a housing, an SMA wire-spring structure, a cone pin, a retraction spring, a locking slider, a steel ball and a double-bevel wedge.

[0007] The cone pin is an element for outputting locking force to the outside of the present invention, and its upper end is conical to prevent the possibility of accidental jamming caused by friction with the inner wall of the shell when it slips out of the shell, thereby ensuring smooth sliding. The double-bevel structure at the lower end of the cone pin is used to cooperate with the double-bevel of the wedge part of the double-bevel wedge block. The bottom of the cone pin is connected to a retraction spring to provide a pulling force for retracting the cone pin into the shell.

[0008] There are two sets of SMA-spring structures, wherein the first set of SMA-spring structures is composed of SMA wire A and a locking spring, and is used to drive the locking slider; the second set of SMA-spring structures is composed of SMA wire B and a compression spring, and is used to drive the double-bevel wedge.

[0009] The shell is a double-chamber structure, including a rectangular chamber and an L-shaped chamber; the rectangular chamber is used to accommodate the first set of SMA-spring structures; the vertical section of the L-shaped chamber is used to accommodate the cone pin, and the horizontal section is used to arrange the second set of SMA-spring structures; the shell chamber is insulated on the side close to the spring. One end of the SMA wire A is fixed on the locking slider, and the other end passes through the locking spring and is fixed on the insulating end of the rectangular chamber; one end of the SMA wire B is fixed on the double-bevel wedge, and the other end passes through the compression spring and is fixed on the insulating end of the L-shaped chamber. Circular through holes are provided on the boundary walls of the rectangular chamber and the L-shaped chamber, and trapezoidal grooves are provided on the locking slider and the double-bevel wedge for accommodating steel balls. The bottom of the cone pin is connected to a retraction spring, and the other end of the retraction spring is fixed on the wall of the L-shaped chamber. When the double-bevel wedge moves to the right and releases the limit on the cone pin, the retraction spring pulls the cone pin down and retracts into the shell chamber.

[0010] Furthermore, the large slope of the double-slope wedge is used to quickly lift the cone pin, and the small slope is used to form friction self-locking after tightening, ensuring that the cone pin will not accidentally retract even if it is subjected to a large longitudinal pressure, thereby stabilizing in the extended state. Analysis shows that when the large-angle slope of the double-slope wedge is preferably designed to be 50°~60° and the small-angle slope is preferably designed to be 8°~15°, the extension process of the cone pin is smooth, and the output ejection force reaches hundreds or even thousands of Newtons.

[0011] Furthermore, in the two sets of SMA-spring structures, springs of different specifications are selected according to different output requirements. The compression spring is responsible for driving the cone pin to tighten, and requires a larger spring force to provide a larger tightening force, thereby meeting the locking force requirements of large space deployment mechanisms; the locking spring is responsible for driving the locking slider to move to push the steel ball to limit the double-bevel wedge, and the required spring load is smaller, and it only needs to overcome the vibration impact under complex operations such as spacecraft launch or orbit change.

[0012] Furthermore, in the two sets of SMA-spring structures, SMA wires of different specifications are selected according to different output requirements, wherein the diameter of SMA wire A is smaller than that of SMA wire B. By rationally designing and matching the SMA wire and the spring, its contraction force and response speed can be optimized, thereby achieving efficient driving of the actuator in different working stages.

[0013] Furthermore, the insulating end of the shell chamber is installed with an insulating support plate, which is made of high-strength insulating material and can ensure reliable insulation between the SMA wire and the shell under the condition of bearing spring force, effectively prevent electrical faults such as arc discharge, and improve the safety and reliability of the driver.

[0014] The working process of the bidirectional driver of the present invention is as follows:

[0015] When the cone pin is in the retracted state, the steel ball is squeezed into the space formed by the groove of the double-bevel wedge block and the circular through hole, the double-bevel wedge block is limited by the steel ball, the steel ball is limited by the locking slider, the locking slider is pressed by the locking spring, and the cone pin is tightened by the retraction spring and will not extend out of the shell, thereby stabilizing in the retracted state.

[0016] When the cone pin needs to be extended, the SMA wire A is heated to shrink it, and the locking slider is pulled to the right. When the groove on the locking slider is aligned with the circular through hole, the double-bevel wedge squeezes the steel ball into the groove of the locking slider under the restoring force of the compression spring, releasing the limit of the double-bevel wedge; the double-bevel wedge continues to move to the left under the action of the compression spring, thereby lifting the cone pin upward and outputting the locking force to the outside. At this time, the device enters the locking position. The first half of the lifting process is matched by the large-angle bevel, and the second half of the stroke is matched by the small-angle bevel.

[0017] When the taper pin needs to be retracted, the SMA wire B is heated and energized to shrink it, and the double-bevel wedge is pulled to the right until the groove on it is aligned with the circular through hole. Under the restoring force of the locking spring, the locking slider moves left to squeeze the steel ball into the groove of the double-bevel wedge. At the same time, the locking spring presses the locking slider to the left to limit the steel ball and lock the double-bevel wedge. At this time, the taper pin moves down under the action of the retraction spring and stabilizes in the retracted state again. At this time, the device enters the unlocking position.

[0018] Compared with the prior art, the large-load bidirectional driver of the present invention has the following technical advantages.

[0019] (1) Simple structure and small volume. The present invention adopts a double-chamber housing, and two sets of SMA-spring structures are arranged in the two chambers respectively to control the protrusion and retraction of the taper pin. The structure is simple and the layout is compact, with the remarkable advantages of small volume and light weight, and can adapt to various working scenarios.

[0020] (2) Strong load-bearing capacity. The two sets of SMA wire-spring structures of the present invention adopt a differential design. The second set of SMA wire-spring structure for driving the taper pin to eject uses a larger spring and thicker SMA wire, so that the driver can provide a larger and continuous locking force, and has a strong load-bearing capacity.

[0021] (3) Smooth movement and high driving reliability. The upper end of the taper pin of the present invention is conical, and the lower end adopts double inclined surfaces. This structure enables the taper pin to move smoothly during the extension and retraction processes, and at the same time ensures the stable output of the tightening force; while the core limiting element, the steel ball, is arranged in the circular through hole and trapezoidal groove of the boundary wall of the two chambers of the housing, and is in point contact with the hole wall and the groove wall, with small frictional resistance. The steel ball will not accidentally fall off or get stuck during the movement process, and both bidirectional drives have high reliability. Description of the Drawings

[0022] Figure 1 is a schematic structural diagram of a memory metal bidirectional driver of the prior art;

[0023] Figure 2 is a schematic structural diagram of a tightening device driven by a shape memory alloy of the prior art;

[0024] Figure 3 is a schematic diagram of the retracted state of the taper pin of the present invention;

[0025] Figure 4 is a schematic diagram of the extended state of the taper pin of the present invention.

[0026] Meanings of the reference numerals in the drawings:

[0027] 1. Taper pin; 2. Housing; 3. Locking slider; 4. Locking spring; 5. SMA wire A; 6. Double inclined surface wedge block; 7. Steel ball; 8. Compression spring; 9. SMA wire B; 10. Retraction spring; 11. Insulating support plate; 201 Rectangular chamber; 202. L-shaped chamber; 203. Circular through hole; 301 Groove A; 601. Groove B. Detailed Embodiments

[0028] The working principle of the present invention will be further described below in conjunction with the drawings and specific embodiments.

[0029] The present invention provides a large-load bidirectional driver, and its structure is asFigures 3 to 4 As shown in the figure, it includes a taper pin 1, a housing 2, a locking slider 3, a locking spring 4, an SMA wire A 5, a double-bevel wedge 6, a steel ball 7, a compression spring 8, an SMA wire B 9, a retraction spring 10 and an insulating support plate 11.

[0030] The upper end of the taper pin 1 is conical, and the lower end is a double-bevel structure that matches the double-bevel of the head of the double-bevel wedge 6. The bottom of the taper pin 1 is connected to the retraction spring 10, and the bottom of the retraction spring 10 is fixed on the wall of the L-shaped chamber. When the double-bevel wedge 6 slides to the right to release the limit on the taper pin 1, the spring force of the retraction spring 10 pulls the taper pin 1 downward and retracts it into the housing 1.

[0031] The SMA wire A 5 and the locking spring 4 form the first set of SMA-spring structure, whose left end is connected to the locking slider 3 and the right end is fixed on the insulating support plate 11 at the right end of the rectangular chamber 201; the SMA wire B 9 and the compression spring 8 form the second set of SMA-spring structure, whose left end is connected to the double-bevel wedge 6 and the right end is fixed on the insulating support plate 11 at the right end of the L-shaped chamber. The second set of SMA-spring structure is used to drive the taper pin 1 to move upward to provide an external locking force; the first set of SMA-spring structure is used to limit the second set of SMA-spring structure when the taper pin 1 is in the retracted state to ensure that the taper pin 1 can be stably maintained in the retracted state.

[0032] The housing 2 has a double-chamber structure, including a rectangular chamber 201 and an L-shaped chamber 202; the left side of the rectangular chamber 201 is closed and the right side is open, and the first set of SMA-spring structure is accommodated therein; both ends of the L-shaped chamber 202 are open, the left vertical section accommodates the taper pin 1, and the right horizontal section accommodates the second set of SMA-spring structure; insulating support plates 11 are respectively fixed at the open ends of the right sides of the rectangular chamber 201 and the L-shaped chamber 202. The left end of the SMA wire A 5 is fixed on the locking slider 3, and the right end passes through the locking spring 4 and is fixed on the insulating support plate 11 of the rectangular chamber 201; the left end of the SMA wire B 9 is fixed on the double-bevel wedge 6, and the right end passes through the compression spring 8 and is fixed on the insulating support plate 11 of the L-shaped chamber 202. A circular through-hole 203 is provided on the partition wall between the rectangular chamber 201 and the L-shaped chamber 202. The diameter of the circular through-hole 203 is larger than that of the steel ball 7, allowing the steel ball 7 to move freely in the hole; trapezoidal grooves for accommodating the steel ball 7, namely groove A 301 and groove B 601, are respectively provided on the locking slider 3 and the double-bevel wedge 6. The right end faces of the groove A 301 and the groove B 601 are both inclined planes to facilitate the movement of the steel ball 7.

[0033] When the taper pin 1 is in the retracted state, the steel ball 7 is squeezed into the space formed by the trapezoidal groove of the double-bevel wedge 6 and the circular through-hole 203. The double-bevel wedge 6 is limited by the steel ball 7, and the taper pin 1 is tightened by the retraction spring 10, so that the taper pin 1 is stabilized in the retracted state. When the taper pin needs to extend to output the locking force externally, the SMA wire A5 is energized and heated to shrink, pulling the locking slider 3 to move to the right. Under the restoring force of the compression spring 8, the double-bevel wedge 6 squeezes the steel ball 7 into the groove of the locking slider 3. The double-bevel wedge 6 loses its restraint and continues to move to the left under the action of the compression spring 8. The large bevel surface of the double-bevel wedge 6 quickly jacks up the taper pin 1 in the first half of the stroke, and the small bevel surface forms frictional self-locking after being tightened, so that the taper pin 1 is stabilized in the extended state. When it is necessary to retract the taper pin 1 again, the SMA wire B 9 is energized and heated to shrink, pulling the double-bevel wedge 6 to move to the right. Under the restoring force of the locking spring 4, the locking slider 3 moves to the left to squeeze the steel ball 7 into the groove of the double-bevel wedge 6. At the same time, the locking spring 4 presses the locking slider 3 to the left to complete the limitation of the steel ball 7, and further realizes the locking of the double-bevel wedge 6. The taper pin 1 moves downward under the action of the retraction spring and completes the retraction and is stabilized in the retracted state.

[0034] It should be noted that the above-mentioned expressions related to directions, such as "top", "bottom", "left", "right", etc., are all based on the directions or positional relationships shown in the drawings, or the directions or positional relationships in which the products of the present invention are usually placed during use, and are only for the convenience of description, rather than indicating or implying that the components involved must have specific directions, structures or operations.

[0035] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A large-load bidirectional driver, characterized in that, It includes an SMA-spring structure, a taper pin (1), a housing (2), a locking slider (3), a double-inclined wedge (6), a steel ball (7), and a retraction spring (10), and is characterized in that There are two sets of the SMA-spring structure. The first set of the SMA-spring structure is composed of an SMA wire A (5) and a locking spring (4) and is used to drive the locking slider (3); the second set of the SMA-spring structure is composed of an SMA wire B (9) and a compression spring (8) and is used to drive the double-inclined wedge (6); The taper pin (1) is used to output a locking force externally. The lower end is a double-inclined structure, which cooperates with the double-inclined surface at the upper left part of the double-inclined wedge (6). The bottom of the taper pin (1) is connected to the retraction spring (10); The housing (2) is a double-chamber structure, including a rectangular chamber (201) and an L-shaped chamber (202). The right ends of the two chambers are insulated. The first set of the SMA-spring structure is arranged in the rectangular chamber (201); the vertical section on the left side of the L-shaped chamber (202) accommodates the taper pin (1), and the horizontal section on the right side is used to arrange the second set of the SMA-spring structure; the left end of the SMA wire A (5) is fixed on the locking slider (3), and the right end passes through the locking spring (4) and is fixed at the insulated end of the rectangular chamber (201); the left end of the SMA wire B (9) is fixed on the double-inclined wedge (6), and the right end passes through the compression spring (8) and is fixed at the insulated end of the L-shaped chamber (202); a circular through-hole (203) with a diameter larger than that of the steel ball (7) is provided on the partition wall between the rectangular chamber (201) and the L-shaped chamber (202), and trapezoidal grooves for accommodating the steel ball (7) are respectively provided on the locking slider (3) and the double-inclined wedge (6); When it is necessary to extend the taper pin, the SMA wire A (5) is energized and heated to shrink, pulling the locking slider (3) to move rightward. Under the restoring force of the compression spring (8), the double-inclined wedge (6) squeezes the steel ball (7) into the groove of the locking slider (3). The double-inclined wedge (6) loses restraint and continues to move leftward under the action of the compression spring (8). The large inclined surface of the double-inclined wedge (6) quickly jacks up the taper pin (1) in the first half, and the small inclined surface forms frictional self-locking after being tightened, so as to stably hold the taper pin (1) in the extended state; When it is necessary to retract the taper pin, the SMA wire B (9) is energized and heated to shrink, pulling the double-inclined wedge (6) to move rightward. Under the restoring force of the locking spring (4), the locking slider (3) moves leftward to squeeze the steel ball (7) into the groove of the double-inclined wedge (6). At the same time, the locking spring (4) presses the locking slider (3) leftward to complete the limit of the steel ball (7), and further realizes the locking of the double-inclined wedge (6). The taper pin (1) moves downward under the action of the retraction spring and completes the retraction and is stably held in the retracted state.

2. The large-load bidirectional driver according to claim 1, characterized in that, The large-angle inclined surface of the double-inclined wedge (6) is designed to be 50° to 60°, and the small-angle inclined surface is designed to be 8° to 15°.

3. The large-load bidirectional driver according to claim 1, wherein Among the two sets of the SMA-spring structure, the spring force of the compression spring (8) is greater than that of the locking spring (4).

4. The large-load bidirectional driver according to claim 1, characterized in that, Among the two sets of the SMA-spring structure, the diameter of the SMA wire A (5) is smaller than that of the SMA wire B (9).

5. The large-load bidirectional driver according to any one of claims 1 to 4, characterized in that, The right end of the housing chamber is insulated by fixing an insulating support plate (11); the insulating support plate is made of a high-strength insulating material.

6. The large-load bidirectional driver according to claim 1, wherein The upper end of the taper pin (1) is tapered to prevent the possibility of accidental jamming due to friction between the taper pin (1) and the inner wall of the housing (2) during the extension process, ensuring smooth sliding.

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