Sma wire driven wedge tight repeatable gripping release mechanism

Abstract

The application provides an SMA wire driven wedge type repeatable holding and releasing mechanism, which comprises a holding end and a limiting end fixed on the holding end. The holding end is reliably held between the upper and lower supporting cylinders through wedge type cooperation between the holding cone ring and the elastic sheet of the lower supporting cylinder; the limiting end limits the position of the holding cone ring in a plug-in limiting pin mode. The application adopts two groups of SMA wire-spring structures as driving components: the first driving component composed of an unlocking SMA wire and a holding spring, which is used to drive the holding cone ring to move up and down, so as to hold or release; the second driving component composed of a triggering SMA wire and a limiting compression spring, which is used to drive the limiting pin to move horizontally, so as to limit or release the limiting of the holding cone ring, and then trigger the mechanism to hold or release. The application has the advantages of large holding force, stable action, rapid response, small volume, simple structure, light mass, high reliability and repeatability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of clamping and releasing mechanism, in particular to a SMA wire driven reusable clamping and releasing mechanism. BACKGROUND

[0002] With the development of aerospace field, the importance of reusable clamping and releasing mechanism is highlighted, for example, the mechanical gripper outside the space station, in order to replace the gripper device conveniently and quickly, the clamping and releasing mechanism plays a crucial role. At the same time, the harsh working conditions also put forward higher reliability requirements for the clamping and releasing mechanism.

[0003] At present, the common reusable clamping and releasing mechanism in China mainly adopts hydraulic power, and the hydraulic drive mode leads to the complex mechanical structure and large mass of the clamping and releasing mechanism, and the complex structure also affects the reliability of the mechanism, so the application in the field of aerospace is limited. SUMMARY

[0004] The present application mainly aims at the shortcomings of the existing reusable clamping and releasing mechanism technology, and provides a SMA wire driven wedge type reusable clamping and releasing mechanism, which realizes clamping through the wedge type cooperation of the clamping cone ring, and is actuated and driven through the SMA wire-spring structure, so that the structure is simple, the mass is light, the mechanism is reusable, and the reliability is high.

[0005] The technical scheme adopted by the present application is as follows: a SMA wire driven wedge type reusable clamping and releasing mechanism, comprising a clamping end and a limiting end fixed on the clamping end. The clamping end comprises a lower supporting cylinder and a clamping connecting assembly, which is used to clamp or release the upper supporting cylinder. The limiting end comprises a clamping mechanism shell and a limiting connecting assembly, which is used to limit the clamping connecting assembly to keep the mechanism in a clamping state or a releasing state. A transverse cavity for installing the limiting connecting assembly is arranged on the outer side of the clamping mechanism shell, and the transverse cavity extends inward along the radial direction and has a slide pin through hole; the clamping mechanism shell is fixedly connected with the lower supporting cylinder and surrounds a longitudinal cavity, and the clamping connecting assembly is installed in the longitudinal cavity.

[0006] The upper end of the lower supporting cylinder is circumferentially distributed with a plurality of elastic sheets, the inner side of the elastic sheet is a cylindrical surface, and the outer side is a conical surface. When the conical surface of the elastic sheet is subjected to extrusion force, the elastic sheet is inwardly folded and tightly presses the upper supporting cylinder, so as to realize clamping.

[0007] The clamping connection assembly includes a clamping cone ring and a first drive assembly. The clamping cone ring is mounted outside the lower support tube. Its upper section features a conical surface on the inside that mates with the outer conical surface of the elastic plate, forming a wedge-like fit. The outer surface of the clamping cone ring is cylindrical and mates with the inner cylindrical surface of the clamping mechanism housing. The outer cylindrical surface of the clamping cone ring also features a stopper structure that mates with the stopper connection assembly. The first drive assembly is installed below the clamping cone ring in the longitudinal cavity and is used to drive the clamping cone ring up and down for clamping or releasing.

[0008] The limiting connection assembly includes a limiting pin and a second drive assembly. The limiting pin is used to limit the axial position of the clamping cone ring and can move radially within the sliding pin hole in the clamping mechanism housing. When the pin is pushed inward, it engages with the limiting structure on the side of the clamping cone ring and disengages from the limiting structure when the pin is pulled outward. The second drive assembly is installed in the transverse cavity of the clamping mechanism housing and is used to drive the limiting pin to move radially, thereby limiting or releasing the clamping cone ring.

[0009] Furthermore, the first drive assembly comprises an SMA wire-spring drive structure consisting of an unlocking SMA wire and a clamping spring. In the clamping state, the clamping spring presses the clamping cone ring upward, forming a wedge-like fit between the clamping cone ring and the elastic sheet, thereby squeezing the elastic sheet inward and pressing the upper support tube, thereby clamping the upper support tube. When the mechanism needs to be released, the unlocking SMA wire is energized, and its contraction pulls the clamping cone ring downward, overcoming the spring force of the clamping spring, thereby disengaging the clamping cone ring from the conical surface of the lower support tube and releasing the wedge-like fit.

[0010] Furthermore, multiple unlocking SMA wires are evenly arranged along the circumference, preferably 2, 3 or 4. Multiple unlocking SMA wires work simultaneously to ensure that the clamping cone ring is evenly stressed and avoid the risk of jamming when moving downward.

[0011] Furthermore, the second drive assembly is an SMA wire-spring drive structure composed of a triggering SMA wire and a limiting compression spring, which is arranged in the transverse direction and installed between the limit pin head and the inner wall of the transverse cavity of the clamping mechanism housing. The triggering SMA wire is used to pull the limit pin out of the limiting structure on the clamping cone ring, thereby triggering the actuation process of the clamping cone ring; one end of the triggering SMA wire is connected to the limit pin head, and the other end is fixed to the inner wall of the transverse cavity of the clamping mechanism housing; when the clamping cone ring needs to be actuated, the triggering SMA wire pulls the limit pin outward. One end of the limiting compression spring is supported on the limit pin head, and the other end is supported on the inner wall of the transverse cavity of the clamping mechanism housing, and is used to drive the limit pin to move inward to cooperate with the limiting structure on the clamping cone ring to limit the clamping cone ring.

[0012] Further, the trigger SMA wire is provided with two roots, and power supply to any one of the SMA wires can pull out the limiting pin to release the limiting of the holding cone ring, and the redundant design can improve the reliability of the mechanism.

[0013] Further, in the two-group SMA wire-spring driving structure adopted by the present application, the springs are all pre-compression springs. When not powered, the elastic recovery force of the spring is greater than the pulling force of the SMA wire; when powered, the force generated by the heating shrinkage of the SMA wire is greater than the elastic recovery force of the spring when reaching the maximum compression amount.

[0014] Compared with the prior art, the SMA wire driving wedge type repeatable holding and releasing mechanism has the following advantages:

[0015] (1) The holding and releasing mechanism holds the upper and lower support cylinders by the conical surface cooperation between the holding cone ring and the lower support cylinder, and the holding is reliable and the holding force is large;

[0016] (2) The present application releases the mechanism by unlocking the SMA wire to drive the axial movement of the holding cone ring, and the releasing mode is stable and has small impact force;

[0017] (3) The present application triggers the mechanism to start holding by triggering the SMA wire to drive the radial movement of the limiting pin to release the axial limiting of the holding cone ring, and the triggering mode of the holding process is fast;

[0018] (4) The present application applies two-group SMA wire-spring structure as a driving component, i.e. the first group driving component composed of the unlocking SMA wire and the holding spring for driving the holding cone ring to move up and down to hold or release, and the second group driving component composed of the trigger SMA wire and the limiting compression spring for driving the limiting pin to move transversely to limit or release the holding cone ring, compared with the existing hydraulic driving mode, has the advantages of small volume, simple structure, light weight, high reliability, etc. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a holding state sectional view of the holding and releasing mechanism of the present application;

[0020] Figure 2 is a release state sectional view of the holding and releasing mechanism of the present application;

[0021] Figure 3 is a structural schematic view of the lower support cylinder.

[0022] Meaning of reference signs:

[0023] 1. Upper support tube; 2. Clamping cone ring; 3. Clamping mechanism housing; 4. Trigger SMA wire; 5. Limiting and pressing spring; 6. Limiting pin; 7. Clamping spring; 8. Unlocking SMA wire; 9. Lower support tube; 901. Elastic sheet. DETAILED DESCRIPTION

[0024] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0025] The present invention provides an SMA wire driven wedge type repeatable clamping and releasing mechanism, the structure of which is as follows: Figures 1-2 As shown, it includes a clamping end and a limiting end fixed on the clamping end. The clamping end includes a lower support tube 9 and a clamping connection assembly, whose function is to enable the lower support tube 9 to clamp or release the upper support tube 1. The limiting end includes a clamping mechanism housing 3 and a limiting connection assembly, whose function is that when the clamping end releases the locking relationship between the upper and lower support tubes, the limiting connection assembly limits the clamping connection assembly to keep the mechanism in a released state. A transverse cavity for installing the limiting connection assembly is provided on the outer surface of the clamping mechanism housing 3, and a sliding pin through hole extends inwardly from the transverse cavity; the clamping mechanism housing 3 is connected to the lower support tube 9, and the clamping connection assembly is installed in the longitudinal cavity surrounded by the two.

[0026] The structure of the lower support tube 9 is as follows Figure 3 As shown, a plurality of elastic sheets 901 are distributed circumferentially at its upper end, and the inner side of the elastic sheet 901 is a cylindrical surface. When subjected to extrusion force, the elastic sheet 901 contracts inward to press the upper support tube 1, thereby realizing the clamping function; the outer side of the elastic sheet 901 is a conical surface, which is used to perform wedge-tight cooperation with the clamping connection component.

[0027] The clamping connection assembly includes a clamping cone ring 2, a clamping spring 7, and an unlocking SMA wire 8. The clamping cone ring 2 is sleeved onto the outside of the lower support tube 9. The inner side of its upper section is flared and has a conical surface that mates with the outer conical surface of the elastic sheet 901, forming a wedge-type fit between the two. The outer side of the clamping cone ring 2 is a cylindrical surface that mates with the inner cylindrical surface of the clamping mechanism housing 3. The outer cylindrical surface of the clamping cone ring 2 also has a limit hole that mates with the limit connection assembly. The clamping spring 7 is a compression spring, arranged axially (i.e., longitudinally as shown), and surrounds the outside of the lower support tube 9. Its upper end is supported on the lower end surface of the clamping cone ring 2, and its lower end is supported on the inner bottom side of the clamping mechanism housing 3. In the clamping state, the clamping spring 7 presses the clamping cone ring 2 upward, thereby squeezing the elastic sheet 901 inward to press the upper support tube 1, thereby achieving a clamping of the upper support tube 1. Two unlocking SMA wires 8 are provided on each side, their upper ends connected to the lower end surface of the clamping cone ring 2 and their lower ends fixed to the inner bottom surface of the clamping mechanism housing 3. When the mechanism needs to be released, both unlocking SMA wires 8 are energized simultaneously, and their contraction pulls the clamping cone ring 2 downward, overcoming the spring force of the clamping spring 7. This disengages the conical surface of the clamping cone ring 2 and the lower support tube 9, releasing the wedge-locked fit. The clamping spring 7 and unlocking SMA wires 8 form the first SMA wire-spring drive structure of the present invention, used to drive the clamping cone ring 2 up and down for clamping or releasing.

[0028] The limiting connection assembly includes a triggering SMA wire 4, a limiting compression spring 5 and a limiting pin 6. Among them, the limiting pin 6 is used to limit the clamping cone ring 2. It can move radially (i.e. horizontally as shown in the figure) in the sliding pin through hole of the clamping mechanism housing 3. When the pin is pushed inward, it can be inserted into the limiting hole on the side of the clamping cone ring 2, thereby limiting its longitudinal position and placing the clamping cone ring 2 in a released position. When the pin is pulled outward, it disengages from the limiting hole and releases the limit on the clamping cone ring 2. The triggering SMA wire 4 is used to trigger the clamping process. One end of the triggering SMA wire is connected to the head of the limiting pin 6, and the other end is fixed to the inner wall of the transverse cavity of the clamping mechanism housing 3. When clamping is required, the triggering SMA wire pulls the limiting pin 6 to move outward, disengages from the limiting hole, and releases the limit on the clamping cone ring 2. The limiter and compression spring 5 is a compression spring used to drive the limiter pin 6 inward to insert into the limit hole, thereby limiting the position of the clamping cone ring 2. One end of the spring is supported by the head of the limiter pin 6, and the other end is supported by the inner wall of the lateral cavity of the clamping mechanism housing 3. The trigger SMA wire 4 and the limiter and compression spring 5 form the second SMA wire-spring drive structure of the present invention, which is used to drive the limiter pin 6 to move laterally to limit or release the clamping cone ring 2.

[0029] The working process of the holding release mechanism of the present invention is as follows:

[0030] When released, the unlocking SMA wire 8 is powered to heat and shrink, overcoming the spring force of the clamping spring 7, pulling the clamping cone ring 2 to move downward. When the clamping cone ring 2 moves down to the limit hole on the outer side and the sliding pin hole of the horizontal cavity of the clamping mechanism shell 3 is aligned, the limit compression spring 5 pushes the limit pin 6 to move inward and insert into the limit hole, completing the limiting of the clamping cone ring 2. At this time, the power supply is disconnected, the clamping relationship of the upper support cylinder 1 by the lower support cylinder 9 is released, and the mechanism enters and stabilizes in the release state shown in FIG. 6. Figure 2 When released, the unlocking SMA wire 8 is powered to heat and shrink, overcoming the spring force of the clamping spring 7, pulling the clamping cone ring 2 to move downward. When the clamping cone ring 2 moves down to the limit hole on the outer side and the sliding pin hole of the horizontal cavity of the clamping mechanism shell 3 is aligned, the limit compression spring 5 pushes the limit pin 6 to move inward and insert into the limit hole, completing the limiting of the clamping cone ring 2. At this time, the power supply is disconnected, the clamping relationship of the upper support cylinder 1 by the lower support cylinder 9 is released, and the mechanism enters and stabilizes in the release state shown in FIG. 6.

[0031] When released, the unlocking SMA wire 8 is powered to heat and shrink, overcoming the spring force of the clamping spring 7, pulling the clamping cone ring 2 to move downward. When the clamping cone ring 2 moves down to the limit hole on the outer side and the sliding pin hole of the horizontal cavity of the clamping mechanism shell 3 is aligned, the limit compression spring 5 pushes the limit pin 6 to move inward and insert into the limit hole, completing the limiting of the clamping cone ring 2. At this time, the power supply is disconnected, the clamping relationship of the upper support cylinder 1 by the lower support cylinder 9 is released, and the mechanism enters and stabilizes in the release state shown in FIG. 6. Figure 1 When released, the unlocking SMA wire 8 is powered to heat and shrink, overcoming the spring force of the clamping spring 7, pulling the clamping cone ring 2 to move downward. When the clamping cone ring 2 moves down to the limit hole on the outer side and the sliding pin hole of the horizontal cavity of the clamping mechanism shell 3 is aligned, the limit compression spring 5 pushes the limit pin 6 to move inward and insert into the limit hole, completing the limiting of the clamping cone ring 2. At this time, the power supply is disconnected, the clamping relationship of the upper support cylinder 1 by the lower support cylinder 9 is released, and the mechanism enters and stabilizes in the release state shown in FIG. 6.

[0032] In addition, it can be understood that in the above embodiment, the limit hole on the outer side of the clamping cone ring 2 serves to accommodate the limit pin 6 and limit the longitudinal position of the clamping cone ring 2. Therefore, preferably, the limit structure can also be replaced by a ring-shaped limit groove, which can reduce the alignment accuracy requirement during assembly of the mechanism and effectively reduce the risk of limit pin jamming, further improving the actuation reliability of the mechanism.

[0033] In the above embodiment, the retention of the clamping state of the mechanism relies on the continuous compression of the clamping cone ring 2 by the elastic restoring force of the clamping spring 7. In a working environment with strong vibration, to prevent accidental release of the mechanism, another similar clamping limit structure can be provided below the release position limit structure (i.e. the limit hole or limit ring-shaped groove described in the above embodiment) on the clamping cone ring 2. When the clamping cone ring 2 moves up to the clamping position, the limit compression spring 5 pushes the limit pin 6 into the limit structure, which limits the clamping cone ring 2 at the clamping position, ensuring that the mechanism is in the clamping state. When release is needed, the trigger SMA wire 4 is powered first to drive the pin, and then the unlocking SMA wire 8 is powered to drive the release.

[0034] It should be noted that the above expressions related to the orientation, such as "inner", "outer", "upper", "lower", etc., are based on the orientation or position relationship shown in the drawings, or the orientation or position relationship when the product is used, and are only for convenience of description, but do not indicate or imply that the parts involved must have a specific orientation, structure or operation.

[0035] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. An SMA wire-driven wedge-tightening repeatable clamping and releasing mechanism, comprising a clamping end and a limit end fixed to the clamping end, characterized in that: The clamping end includes a lower support tube (9) and a clamping connection assembly for enabling the lower support tube (9) to clamp the upper support tube (1); the limiting end includes a clamping mechanism housing (3) and a limiting connection assembly for limiting the clamping connection assembly to maintain the mechanism state; the clamping mechanism housing (3) is fixedly connected to the lower support tube (9) and encloses a longitudinal cavity, and the clamping connection assembly is installed in the longitudinal cavity; a transverse cavity for installing the limiting connection assembly is provided on the outer surface of the clamping mechanism housing (3), and a sliding pin through hole extends inwardly from the transverse cavity; The upper end of the lower support tube (9) is provided with a plurality of elastic sheets (901) distributed along the circumferential direction. The elastic sheets (901) are naturally opened, and the inner sides thereof are cylindrical surfaces. When subjected to extrusion force, the elastic sheets (901) are retracted inwards and tightly embrace the upper support tube (1); the outer sides of the elastic sheets (901) are conical surfaces, and are used for wedge-tightening with the embracing connection assembly. The clamping connection assembly comprises a clamping cone ring (2) and a first drive assembly; wherein the clamping cone ring (2) is sleeved on the outside of the lower support tube (9), and the inner side of the upper section thereof is in a trumpet shape, and is provided with a conical surface that matches the outer conical surface of the elastic sheet (901), and a wedge-type fit can be formed between the two; the outer side surface of the clamping cone ring (2) is a cylindrical surface, and is provided with a limiting structure that matches the limiting connection assembly; the first drive assembly is an SMA wire-spring drive structure composed of a clamping spring (7) and an unlocking SMA wire (8), which is arranged in the longitudinal direction and installed between the lower end surface of the clamping cone ring (2) and the bottom inner wall of the clamping mechanism housing (3); the clamping spring (7) surrounds the outside of the lower support tube (9); the first drive assembly is used to drive the clamping cone ring (2) to move up and down for clamping or releasing; The limiting connection assembly includes a limiting pin (6) and a second drive assembly; wherein the limiting pin (6) is used to limit the longitudinal position of the clamping cone ring (2), and can move laterally in the sliding pin through hole. When the pin is pushed inward, it cooperates with the limiting structure of the clamping cone ring (2), thereby limiting the longitudinal position of the clamping cone ring (2); when the pin is pulled outward, it disengages from the limiting structure, thereby releasing the limiting of the clamping cone ring (2); the second drive assembly is an SMA wire-spring drive structure composed of a triggering SMA wire (4) and a limiting compression spring (5), which is arranged in the transverse direction and installed between the head of the limiting pin (6) and the inner wall of the transverse cavity of the clamping mechanism housing (3). The second drive assembly is used to drive the limiting pin (6) to move laterally to achieve limiting or releasing the limiting of the clamping cone ring (2).

2. The SMA wire-driven wedge-tightening repeatable tightening and releasing mechanism according to claim 1, characterized in that: The unlocking SMA wires (8) are evenly arranged in 2, 3 or 4 pieces along the circumferential direction, and the multiple wires work synchronously.

3. The SMA wire-driven wedge-tightening repeatable tightening and releasing mechanism according to claim 1, characterized in that: Two trigger SMA wires (4) are provided, and the limit pin (6) can be pulled out by energizing any one of them.

4. The SMA wire-driven wedge-tightening repeatable tightening and releasing mechanism according to claim 1, characterized in that: The holding spring (7) and the limit pressing spring (5) are both pre-compressed springs; when not energized, the elastic restoring force of the springs (5, 7) is greater than the tension of the SMA wires (4, 8); when energized, the force generated by the thermal contraction of the SMA wires (4, 8) is greater than the elastic restoring force of the springs (5, 7) when they reach maximum compression.

5. The SMA wire driven wedge-tightening repeatable tightening and releasing mechanism according to claim 1, characterized in that: The limiting structure on the outer cylindrical surface of the clamping cone ring (2) is provided in two layers, the upper limiting structure corresponding to the clamping cone ring (2) is in a releasing position, and the lower limiting structure corresponding to the clamping cone ring (2) is in a clamping position.

6. The SMA wire driven wedge-tightening repeatable tightening and releasing mechanism according to claim 1, characterized in that: The limiting structure on the outer cylindrical surface of the clamping cone ring (2) is a limiting hole.

7. The SMA wire driven wedge-tightening repeatable tightening and releasing mechanism according to claim 1, characterized in that: The limiting structure on the outer cylindrical surface of the clamping cone ring (2) is an annular limiting groove.

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