Variable stroke shape memory alloy actuation device

Abstract

The application relates to a variable-stroke shape memory alloy actuating device which comprises a telescopic connecting rod one, a telescopic connecting rod two, a base support, a sliding rail, a sliding block, a shape memory alloy wire and a reset spring; the telescopic connecting rod one and the telescopic connecting rod two are located on surface I; the two ends of the telescopic connecting rod one are respectively pivotally connected with the base support and the left end of the telescopic connecting rod two, the right end of the telescopic connecting rod two is pivotally connected with the sliding block, and the sliding block is slidingly connected with the sliding rail; one end of the shape memory alloy wire is fixedly connected with the base support, and the other end is rotatably connected with the middle part of the telescopic connecting rod one; the two ends of the reset spring are respectively fixedly connected with the sliding rail and the sliding block; the cooperation relationship of the components satisfies that, when power is on or off, the sliding block is driven to do reciprocating motion through the telescopic connecting rod one and the telescopic connecting rod two along with the deformation of the shape memory alloy wire and the action of the reset spring. The device is simple in structure, and solves the problems of insufficient stroke of the shape memory alloy actuating device and inconvenient stroke amplification ratio adjustment.

Description

Technical Field

[0001] This invention belongs to the field of actuator technology, specifically relating to a shape memory alloy actuator with variable stroke. Background Technology

[0002] Compared with traditional electromechanical, hydraulic, and pneumatic actuators, shape memory alloy (SMA) actuators have advantages such as simple structure, high energy density, and low noise. Moreover, they are stable and reliable in operation and are widely used in fields such as bionic robots, microelectromechanical systems, and aerospace.

[0003] Shape memory alloys also have some drawbacks when applied to actuators, the most prominent being their relatively small actuation strain. Taking nickel-titanium shape memory alloys, currently the best performing alloys overall, as an example, their maximum recoverable strain is generally around 8%. For cyclic actuators in fields with high fatigue requirements, such as optical image stabilization, autofocus, and robotics, the actuation strain is typically below 4% to ensure long-term stable use. For instance, patent CN111380421A discloses an active turbulence actuator mechanism driven by a shape memory alloy wire. This mechanism uses a shape memory alloy wire to pull two horizontal sliders, converting this horizontal motion into vertical slider motion via connecting rods at both ends. The entire device requires three sliders, making the structure relatively cumbersome, and the entire device suffers from the problem of a small stroke of the shape memory alloy wire.

[0004] To achieve a greater stroke in the aforementioned device, the length of the shape memory alloy wire must be increased. However, this not only increases the complexity of the actuator structure and occupies more space, but longer wires often result in slower response speeds. Alternatively, the shape memory alloy wire can be made into a spring to increase the actuation stroke, but this reduces the actuator's driving force, and the lower stiffness of the spring further slows down the actuator's response. Therefore, there is an urgent need to develop a shape memory alloy actuation device that can both increase the stroke of the shape memory alloy to avoid using longer wires and avoid significantly reducing the actuator's response speed due to reduced system stiffness.

[0005] To address the aforementioned issues, patent CN109774985A discloses a connection and release mechanism driven by a shape memory alloy with a large stroke and high load. Its main principle is to amplify the displacement using a lever mechanism. Although it can amplify the displacement, adjusting the amplification ratio on the device itself requires changing the size and position of the device components, which leads to inconvenience in operation. Therefore, there is a problem that the stroke amplification factor is not adjustable. Summary of the Invention

[0006] The purpose of this invention is to solve the problems existing in the prior art and to provide a shape memory alloy actuation device with variable stroke.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A variable stroke shape memory alloy actuation device includes a telescopic link one, a telescopic link two, a base bracket, a slide rail, a slider, a shape memory alloy wire, and a return spring;

[0009] The shape memory alloy wire uses a material with shape memory effect. The shape memory effect material can be any one of nickel-titanium-based shape memory alloy, copper-based shape memory alloy, iron-based shape memory alloy, etc. The telescopic link one and telescopic link two are equipped with fixing bolts. The length of telescopic link one and telescopic link two can be adjusted according to the needs during use. After adjusting to the required length, the length of the link is fixed by fixing bolts.

[0010] Telescopic link one and telescopic link two are both located on surface I; the base bracket and slide rail are both located on surface II, and the length direction of the base bracket is parallel to the left and right direction; surface I and surface II are parallel to each other;

[0011] The left end of telescopic link one is pivotally connected to the base support, and the pivot point is denoted as point A. The right end of telescopic link one is pivotally connected to the left end of telescopic link two, and the pivot point is denoted as point B. The right end of telescopic link two is pivotally connected to the slider, and the pivot point is denoted as point C. The slider is slidably connected to the slide rail, and the slide rail and the base support are perpendicular to each other. Telescopic link one and telescopic link two are connected by a rotatable pivot, which serves as an intermediary for the movement of the shape memory alloy wire and the slider. There are three rotatable pivots, among which the pivot connected to the base support is raised to keep it on the same horizontal plane as the other pivots.

[0012] The shape memory alloy wire is located on surface I; the shape memory alloy wire is located to the right of point A, and the two ends of the shape memory alloy wire are denoted as end m and end n respectively. End m of the shape memory alloy wire is fixedly connected to the base bracket, and end n is rotatably connected to the middle of the telescopic connecting rod.

[0013] The return spring and the slide rail are parallel to each other. The return spring is located between point C and the base bracket. The two ends of the return spring are denoted as p end and q end, respectively. The q end is closer to point C. The p end of the return spring is fixedly connected to the slide rail, and the q end of the return spring is fixedly connected to the slider.

[0014] The coordination relationship of each component satisfies the following: When energized, the shape memory alloy wire deforms, which drives the slider to move through telescopic link one and telescopic link two, causing the return spring to be compressed; when de-energized, the return spring drives the slider to move, which drives the shape memory alloy wire to restore its deformation through telescopic link one and telescopic link two.

[0015] Surface I and Surface II are either vertical or horizontal.

[0016] When the two planes are vertical, the return spring is in a slightly compressed state under the influence of the slider's gravity in the initial state; when the two planes are horizontal, the return spring is in a natural uncompressed state in the initial state.

[0017] When energized, the shape memory alloy wire contracts, causing the first telescopic link to rotate around a pivot fixed to the base. The other end of the first telescopic link is connected to the second telescopic link via the pivot, and the other end of the second telescopic link drives the slider to move linearly along the slide rail via the pivot. The force transmitted from the shape memory alloy wire to the slider through the first and second telescopic links is greater than the sum of the spring force of the return spring and the frictional force between the slider and the slide rail, thus ensuring that the shape memory alloy wire can compress the return spring downwards or forwards. The entire process converts the contraction displacement of the shape memory alloy wire into the linear motion of the slider. A circle O is formed with point A as the center and the distance from point A to the n-end of the shape memory alloy wire as the radius. A circle P is formed with the length of the first telescopic link from point A to point B as the radius. Circles O and P are concentric circles. When the shape memory alloy... When the wire contracts and drives the telescopic link one to rotate around point A, the n end of the shape memory alloy wire becomes the n' end, and the length of the wire changes from mn to mn'. The wire contraction distance Δl = mn - mn'. The wire contraction drives the telescopic link one to rotate by an angle θ, and causes point B to move around circle P to B'. The length of the arc BB' = |AB| × θ. Point B further drives the slider from C to C' through the telescopic link two. The length of CC' is proportional to the length of the arc BB'. Since BB' > nn' > Δl, the linear motion stroke of the slider is greater than the contraction displacement stroke of the shape memory alloy wire. Moreover, the longer the length AB of the telescopic link one, the larger the length of the arc BB', and the larger the stroke CC' transmitted to the slider. Therefore, this invention can realize the amplification of the contraction displacement stroke of the shape memory alloy wire.

[0018] When the power is off, the return spring acting on the slider pushes the slider to move in the opposite direction and drives the shape memory alloy wire to extend through the telescopic link 2 and telescopic link 1; the elastic force of the return spring is transmitted to the shape memory alloy wire through the telescopic link 1 and telescopic link 2, which is greater than the detwinning stress of the shape memory alloy at room temperature, thus ensuring that the shape memory alloy wire can be stretched and restored.

[0019] The above process is repeated to achieve the reciprocating motion of the slider. When the length of the telescopic link is increased, the ratio of the radii of the two concentric circles, the outer circle P and the inner circle O, becomes larger. The increased radius ratio leads to an increase in the length of the arc BB' on circle P, which in turn increases the stroke CC' of the slider. That is, the contraction stroke of the shape memory alloy wire is amplified. Therefore, by adjusting the length of the telescopic link, the radius of circle P can be changed, thereby changing the amplification factor of the stroke.

[0020] The device of this invention has greater rigidity than traditional displacement amplification mechanisms, and the amplification stroke can be adjusted as needed. Furthermore, this invention defines the direction of motion of the shape memory alloy drive device, enabling it to achieve reciprocating motion in a one-dimensional linear direction.

[0021] As a preferred technical solution:

[0022] As described above, in a variable stroke shape memory alloy actuation device, the slide rail is located on the right side of the base bracket and is connected to it in an "L" shape.

[0023] As described above, in a variable stroke shape memory alloy actuation device, the m end of the shape memory alloy wire is fixedly connected to the base support via a fastener and a fixing plate; the fixing plate is fixedly connected to the base support, the fastener is detachably connected to the fixing plate, and the shape memory alloy wire is detachably connected to the fastener.

[0024] As described above, a variable stroke shape memory alloy actuation device includes a fastener comprising a bolt with a hole, a washer, and a nut; the shank of the bolt with a hole passes through the fixing plate, the washer, and the nut in sequence, and the shank of the bolt with a hole has a through hole a, through which a shape memory alloy wire passes, and the shape memory alloy wire is clamped by the washer and the nut at the same time, or by the fixing plate and the washer at the same time.

[0025] As described above, in a variable stroke shape memory alloy actuation device, the fastener is a string rod; the string rod passes through a fixed plate, and a through hole b is provided on the string rod. The shape memory alloy wire is wound around the string rod and then passes through the through hole b. The friction between the two is used to fix the shape memory alloy wire (similar to the way guitar and erhu strings are fixed).

[0026] As described above, in a variable stroke shape memory alloy actuation device, the n-end of the shape memory alloy wire is rotatably connected to the middle of the telescopic connecting rod through a hook and a slide bar.

[0027] The telescopic link 1 has a through hole in the middle, and the slide rod is fixed in the through hole. The slide rod is perpendicular to surface II and perpendicular to the length direction of the telescopic link 1.

[0028] The hook and ring are fitted onto the sliding rod with a clearance fit.

[0029] The n-end of the shape memory alloy wire is fixedly connected to the hook and loop.

[0030] As described above, in a variable stroke shape memory alloy actuation device, the slide bar is made of an insulating material with a friction coefficient of less than 0.08, preferably made of polytetrafluoroethylene with a friction coefficient of less than 0.08 and which is insulating, and the hook is made of a conductive material.

[0031] As described above, in a variable stroke shape memory alloy actuation device, the m-end of the shape memory alloy wire and the hook are simultaneously connected to a drive module, which is connected to the positive and negative terminals of a power supply, thereby enabling the drive module to control the on / off frequency of the circuit.

[0032] As described above, a variable stroke shape memory alloy actuation device comprises a slider consisting of a moving part, a C-shaped block a, and a C-shaped block b;

[0033] The moving part is slidably connected to the slide rail. C1-shaped blocks a and b are distributed on the left and right sides of the moving part, fitted onto the slide rail, and simultaneously fixedly connected to the moving part. The right end of the telescopic link two is pivotally connected to C1-shaped blocks a and b (the right end of the telescopic link two can also be pivotally connected to the moving part. In this case, the hub on the base bracket and the hub on the moving part need to be raised, and the area available for hub installation on the moving part is smaller. Compared to the former, pivoting the right end of the telescopic link two to the C1-shaped block is preferable because the C1-shaped block has a certain thickness. This way, only the hub on the base bracket needs to be raised, and the surface area available for hub installation on the C1-shaped block is larger, which can prevent the link from rubbing against the slide rail plane). The q end of the return spring is fixedly connected to the moving part.

[0034] As described above, in a variable stroke shape memory alloy actuation device, the p end of the return spring is fixedly connected to the slide rail via a support member, and the support member is fixedly connected to both the return spring and the slide rail.

[0035] As described above, in a variable stroke shape memory alloy actuation device, both the moving part and the support part are convex parts, each consisting of a wide portion and a narrow portion. The q-end of the return spring is fitted onto and fixedly connected to the narrow portion of the moving part, and the p-end of the return spring is fitted onto and fixedly connected to the narrow portion of the support part.

[0036] Beneficial effects:

[0037] (1) The present invention forms two concentric circles with proportional radii through a telescopic link. When the initial angle and the length of the shape memory alloy wire are the same, the different proportions of the slider stroke can be magnified by adjusting the length of the telescopic link.

[0038] (2) The driving power source of the present invention is a shape memory alloy wire, which has the advantages of high power density, light weight and strong driving capability. The system can be put into operation by heating through a simple power circuit. At the same time, the frequency of power on and off is controlled by the driving module to realize the frequency of reciprocating motion of the braking device.

[0039] (3) The two telescopic connecting rods of the present invention are rigidly connected to the base support and the slider, so that the whole system maintains a large rigidity. Compared with the stroke amplification mechanism such as shape memory alloy spring, the actuation device of the present invention has the advantage of fast response speed. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the variable stroke shape memory alloy actuation device of the present invention;

[0041] Figure 2 This is a schematic diagram of the connection structure between the shape memory alloy wire, the telescopic connecting rod, and the base support in this invention.

[0042] Figure 3 This is a schematic diagram of the connection structure between a fastener and a shape memory alloy wire according to the present invention.

[0043] Figure 4 This is a schematic diagram of the connection structure between a fastener and a shape memory alloy wire according to another structure of the present invention;

[0044] Figure 5 This is a top view of the bolt with holes according to the present invention;

[0045] Figure 6 This is a top view of the chord of the present invention;

[0046] Figure 7 This is an initial state diagram of the device when switching the magnification ratio according to the present invention;

[0047] Figure 8 This is a schematic diagram demonstrating the enlarged stroke process of the present invention, wherein (a) is the state before power is applied and (b) is the state after power is applied;

[0048] Figure 9 This is a schematic diagram illustrating the movement principle of the telescopic linkage when the actuator of the present invention is powered on and off;

[0049] Among them, 1-power supply, 2-drive module, 3-base bracket, 4-hub, 5-shape memory alloy wire, 6-telescopic link one, 7-support component, 8-fixing bolt, 9-reset spring, 10-telescopic link two, 11-moving component, 12-cubic block a, 13-slide rail, 14-through hole b, 15-hook ring, 16-fastener, 17-slide rod, 18-washer, 19-bolt with hole, 20-fixing plate, 21-through hole a, 22-nut, 23-chord. Detailed Implementation

[0050] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0051] A variable stroke shape memory alloy actuator, such as Figure 1 As shown, it includes a telescopic link 1 6, a telescopic link 2 10, a base bracket 3, a slide rail 13, a shape memory alloy wire 5, a fixing plate 20, a fastener 16, a hook 15, a slide bar 17, a drive module 2, a slider, a return spring 9, and a support 7.

[0052] Telescopic link 6 and telescopic link 10 are both located on surface I;

[0053] The base bracket 3 and the slide rail 13 are both located on surface II. The slide rail 13 and the base bracket 3 are perpendicular to each other. The slide rail 13 is located on the right side of the base bracket 3 and is connected to it in an "L" shape. The length direction of the base bracket 3 is parallel to the left and right direction.

[0054] Surface I and Surface II are parallel to each other;

[0055] The telescopic link 6 has a through hole in the middle. The left end of the telescopic link 6 is pivotally connected to the base bracket 3. The pivot point is marked as point A. The right end of the telescopic link 6 is pivotally connected to the left end of the telescopic link 10. The pivot point is marked as point B.

[0056] The shape memory alloy wire 5 is located on surface I and to the right of point A, with its two ends denoted as end m and end n, respectively.

[0057] like Figure 3 or Figure 4 As shown, the fixing plate 20 is fixedly connected to the base bracket 3;

[0058] like Figure 2 , Figure 3 As shown, fastener 16 includes a bolt with a hole 19, a washer 18, and a nut 22; as Figure 5 As shown, the shank of the bolt with holes 19 passes through the fixing plate 20, the washer 18, and the nut 22 in sequence. The m end of the shape memory alloy wire 5 passes through the through hole a 21 on the shank of the bolt with holes 19 and is clamped by the washer 18 and the nut 22, or by the fixing plate 20 and the washer 18.

[0059] Or, such as Figure 4 , Figure 6As shown, fastener 16 is chord 23; chord 23 passes through fixing plate 20; the m end of shape memory alloy wire 5 passes through through hole b 14 on chord 23, and shape memory alloy wire 5 passes through through hole b 14 after being wound around chord 23.

[0060] The n-end of the shape memory alloy wire 5 is fixedly connected to the hook 15, which is sleeved on the slide rod 17 with a clearance fit. The slide rod 17 is fixed in the through hole in the middle of the telescopic connecting rod 6. The slide rod 17 is perpendicular to surface II and perpendicular to the length direction of the telescopic connecting rod 6. The slide rod 17 is made of an insulating material with a friction coefficient of less than 0.08, and the hook 15 is made of a conductive material.

[0061] The drive module 2 is connected to the m end of the shape memory alloy wire 5 and the hook 15, and is also connected to the positive and negative terminals of the power supply 1, so that the drive module 2 controls the on and off frequency of the circuit.

[0062] The slider consists of a movable component 11, a C-shaped block a 12, and a C-shaped block b. The movable component 11 is slidably connected to the slide rail 13. The C-shaped blocks a 12 and b are distributed on the left and right sides of the movable component 11, fitted onto the slide rail 13, and simultaneously fixedly connected to the movable component 11. The right end of the telescopic connecting rod 10 is pivotally connected to the C-shaped blocks a 12 and b, and the pivot point is denoted as point C.

[0063] The return spring 9 and the slide rail 13 are parallel to each other. The return spring 9 is located between point C and the base bracket 3. The two ends of the return spring 9 are denoted as p end and q end, respectively, with q end being closer to point C.

[0064] Both the movable part 11 and the support part 7 are convex parts, and the convex parts are composed of a wide part and a narrow part;

[0065] The q end of the return spring 9 is sleeved on the narrow part of the moving part 11 and fixedly connected thereto. The p end of the return spring 9 is sleeved on the narrow part of the support part 7 and fixedly connected thereto. The support part 7 is fixedly connected to the slide rail 13.

[0066] The coordination relationship of each component satisfies the following: when energized, the shape memory alloy wire 5 deforms, which drives the slider to move through the telescopic connecting rod 1 6 and the telescopic connecting rod 2 10, causing the return spring 9 to be compressed; when de-energized, the return spring 9 drives the slider to move, which drives the shape memory alloy wire 5 to recover its deformation through the telescopic connecting rod 1 6 and the telescopic connecting rod 2 10.

[0067] The above-mentioned device can be actuated horizontally or vertically. The following is a brief description of its operation, using a vertically positioned device as an example. Figure 8 , Figure 9 As shown:

[0068] When power supply 1 does not supply power to shape memory alloy wire 5, the slider position is as follows: Figure 8 As shown in (a);

[0069] When power supply 1 heats the shape memory alloy wire 5, the wire contracts, pulling the telescopic link 6 downwards. This causes the C-shaped blocks a 12 and b, connected to the telescopic link 10 at the other end, to move. The movement of C-shaped blocks a 12 and b is limited by slide rail 13 to a direction parallel to the initial state of the shape memory alloy wire 5. Because a circle O is formed with pivot point A as the center and the distance from pivot point A to the connection point n between the shape memory alloy wire 5 and the telescopic link 6 as the radius, and another circle P is formed with the length from pivot point A to pivot point B (i.e., the length of the telescopic link 6) as the radius, these two circles form concentric circles with proportional radii. By adjusting the length of the telescopic link 6, the stroke is magnified at different ratios; that is, the contraction stroke of the shape memory alloy wire 5 is magnified and reflected in the movement distance of C-shaped blocks a 12 and b. Figure 8 As shown in (b), the C-shaped block a 12 and the C-shaped block b compress the return spring 9 through the moving part 11;

[0070] When the power supply 1 is disconnected, the reset spring 9 provides a biasing force through the moving part 11 to return the C-shaped blocks a 12 and b to their original positions. At the same time, the shape memory alloy wire 5 is stretched and reset, and the telescopic connecting rod also returns to its original position. In this process of power on and off, the entire device achieves a reciprocating motion defined by one direction.

[0071] like Figure 8 As shown in (a), the length of telescopic link one is 113mm, the length of telescopic link two is 113mm, the length of shape memory alloy wire is 40mm, the initial angle between telescopic link one and the base bracket is 45°, point n is located at the midpoint of telescopic link one, and the radius ratio is 2.

[0072] After power is applied, the actuator is powered by Figure 8 (a) becomes Figure 8 (b) The length of the shape memory alloy wire is shortened by 3.2 mm, and the slider moves downward by 6.8 mm. The comparison shows that the slider's travel on the slide rail is significantly greater than that of the shape memory alloy wire. The actuator has the function of stroke amplification, with an amplification factor of 2.1 times.

[0073] Keeping the length of the shape memory alloy wire and the initial angle parameters between the telescopic connecting rod and the base bracket constant, Figure 8 In (a), the length of telescopic link one is adjusted to 169.5mm, and the length of telescopic link two is adjusted to 169.5mm; Figure 8 (a) becomes Figure 8(b) After that, the slider moves down 12.4mm, and the stroke magnification factor is 3.9 times. By comparison, it can be seen that the present invention can change the stroke magnification factor by adjusting the length of the telescopic connecting rod.

[0074] The specific steps for using the above device are as follows:

[0075] (1) The shape memory alloy wire is installed on the base bracket and the telescopic connecting rod. Pre-strain is applied along the length of the shape memory alloy wire. The n end of the shape memory alloy wire is sleeved on the hook ring. A rectangular hole is cut out on the telescopic connecting rod. The hook ring is sleeved on the slide rod. The slide rod is installed at both ends of the rectangular hole. The m end of the shape memory alloy wire passes through the small hole of the base bracket and is fixed and clamped at the bottom with fasteners. One end of the wire connecting the drive module is connected to the hook ring, and the other end is connected to the m end of the wire passing through the fasteners. The drive module is connected to the positive and negative terminals of the power supply. The shape memory alloy wire is connected to the power supply circuit. The drive module controls the switching frequency of the circuit.

[0076] (2) When the power circuit is energized, the shape memory alloy wire contracts. Since the lower end of the shape memory alloy wire is fixed, when the shape memory alloy wire contracts, it will drive the telescopic link one to move downward, thereby driving the telescopic link two connected to the other end. Through the mobility of the two telescopic links, the slider is pulled down along the slide rail. At the same time, the telescopic link one forms two concentric circles with proportional radii, which realizes the amplification of the stroke. When the power is turned off, the reset spring pushes the slider to move upward, and at the same time pulls the shape memory alloy wire back to its original length. The above power-on and power-off cycles are repeated to realize the reciprocating motion of the slider. The frequency of reciprocating motion can be changed by controlling the power-on and power-off frequency through the drive module.

Claims

1. A shape memory alloy actuation device with variable stroke, characterized in that, It includes a telescopic link one (6), a telescopic link two (10), a base bracket (3), a slide rail (13), a slider, a shape memory alloy wire (5), and a return spring (9); Telescopic link one (6) and telescopic link two (10) are both located on surface I; base bracket (3) and slide rail (13) are both located on surface II, and the length direction of base bracket (3) is parallel to the left and right direction; surface I and surface II are parallel to each other; The left end of the telescopic link 1 (6) is pivotally connected to the base bracket (3), and the pivot point is marked as point A. The right end of the telescopic link 1 (6) is pivotally connected to the left end of the telescopic link 2 (10), and the pivot point is marked as point B. The right end of the telescopic link 2 (10) is pivotally connected to the slider, and the pivot point is marked as point C. The slider is slidably connected to the slide rail (13), and the slide rail (13) and the base bracket (3) are perpendicular to each other. The shape memory alloy wire (5) is located on surface I; the shape memory alloy wire (5) is located to the right of point A. The two ends of the shape memory alloy wire (5) are respectively called the m end and the n end. The m end of the shape memory alloy wire (5) is fixedly connected to the base bracket (3), and the n end is rotatably connected to the middle of the telescopic connecting rod (6). The n-end of the shape memory alloy wire (5) is rotatably connected to the middle of the telescopic connecting rod (6) via a hook (15) and a slide rod (17); The telescopic link 1 (6) has a through hole in the middle, and the slide rod (17) is fixed in the through hole. The slide rod (17) is perpendicular to surface II and perpendicular to the length direction of the telescopic link 1 (6). The hook (15) is fitted onto the slide bar (17) with a clearance fit; The n-end of the shape memory alloy wire (5) is fixedly connected to the hook (15); The reset spring (9) and the slide rail (13) are parallel to each other. The reset spring (9) is located between point C and the base bracket (3). The two ends of the reset spring (9) are respectively called the p end and the q end. The q end is close to point C. The p end of the reset spring (9) is fixedly connected to the slide rail (13), and the q end of the reset spring (9) is fixedly connected to the slider. The coordination relationship of each component satisfies the following: When the power is on, the shape memory alloy wire (5) deforms and drives the slider to move through the telescopic link one (6) and the telescopic link two (10), which causes the return spring (9) to be compressed; when the power is off, the return spring (9) drives the slider to move and drives the shape memory alloy wire (5) to recover its deformation through the telescopic link one (6) and the telescopic link two (10).

2. The variable stroke shape memory alloy actuation device according to claim 1, characterized in that, The m end of the shape memory alloy wire (5) is fixedly connected to the base bracket (3) by a fastener (16) and a fixing plate (20); the fixing plate (20) is fixedly connected to the base bracket (3), the fastener (16) is detachably connected to the fixing plate (20), and the shape memory alloy wire (5) is detachably connected to the fastener (16).

3. The variable stroke shape memory alloy actuation device according to claim 2, characterized in that, The fastener (16) includes a bolt with holes (19), a washer (18), and a nut (22); the shank of the bolt with holes (19) passes through the fixing plate (20), the washer (18), and the nut (22) in sequence. The shank of the bolt with holes (19) is provided with a through hole a (21). The shape memory alloy wire (5) passes through the through hole a (21). The shape memory alloy wire (5) is clamped by the washer (18) and the nut (22) at the same time, or by the fixing plate (20) and the washer (18) at the same time.

4. The variable stroke shape memory alloy actuation device according to claim 2, characterized in that, The fastener (16) is a chord (23); the chord (23) passes through the fixing plate (20), and the chord (23) has a through hole b (14). The shape memory alloy wire (5) is wound around the chord (23) and then passes through the through hole b (14).

5. The variable stroke shape memory alloy actuation device according to claim 1, characterized in that, The slide bar (17) is made of insulating material with a friction coefficient of less than 0.08, and the hook (15) is made of conductive material.

6. The variable stroke shape memory alloy actuation device according to claim 5, characterized in that, The m end of the shape memory alloy wire (5) and the hook (15) are connected to a drive module (2) at the same time. The drive module (2) is connected to the positive and negative terminals of a power supply (1), so that the drive module (2) controls the on and off frequency of the circuit.

7. The variable stroke shape memory alloy actuation device according to claim 1, characterized in that, The slider consists of a movable component (11), a C-shaped block a (12), and a C-shaped block b; The movable part (11) is slidably connected to the slide rail (13). The C-shaped blocks a (12) and b are distributed on the left and right sides of the movable part (11), fitted on the slide rail (13), and fixedly connected to the movable part (11). The right end of the telescopic link two (10) is pivotally connected to the C-shaped blocks a (12) and b. The q end of the return spring (9) is fixedly connected to the movable part (11).

8. A variable stroke shape memory alloy actuation device according to claim 7, characterized in that, The p end of the return spring (9) is fixedly connected to the slide rail (13) through a support member (7), and the support member (7) is fixedly connected to both the return spring (9) and the slide rail (13).

9. A variable stroke shape memory alloy actuation device according to claim 8, characterized in that, Both the moving part (11) and the supporting part (7) are convex parts, which are composed of a wide part and a narrow part. The q end of the return spring (9) is sleeved on the narrow part of the moving part (11) and fixedly connected to it. The p end of the return spring (9) is sleeved on the narrow part of the supporting part (7) and fixedly connected to it.

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