An SMA linear actuator

Abstract

The present invention relates to an SMA linear actuator, comprising: an SMA winding mechanism: comprising an SMA wire, a driving spindle, a spindle pulley mounted on the driving spindle, and a transition pulley group located next to the driving spindle, one end of the SMA wire is wound and fixed on the spindle pulley, and the other end passes through the transition pulley group and is fixed, and the SMA wire is also energized; a heat dissipation mechanism: it is arranged next to the SMA winding mechanism and is used to dissipate heat for the SMA wire; an actuator: comprising an inner tube, an outer tube and a connecting end plate, one end of the inner tube is connected to the driving spindle, and the other end is fixedly connected to the connecting end plate, and the outer tube itself can be extended and retracted along the driving spindle direction, and one end of the inner tube is fixed, and the other end is fixedly connected to the connecting end plate. The present invention can better realize linear drive, has a simple structure, and has a large output displacement.

Description

Technical Field

[0001] The invention belongs to the technical field of drivers and relates to an SMA linear drive. Background Art

[0002] SMA (shape memory alloy) is a special material with shape memory effect, which has the advantages of large strain, large output force, high power-to-weight ratio, good wear resistance and no noise. SMA is widely used as a driving element in aerospace, medical equipment, automation, power and many other fields due to its unique shape memory effect, superelasticity and superior wear resistance. However, there are still some shortcomings in the existing SMA actuators. The existing SMA actuators are relatively complex in structure, lack stability, are large in size, and have small output stroke and output force.

[0003] The University of Science and Technology of China (Zhang Yiliao, Dong Erbao, Xu Min, et al. SMA linear motor based on displacement accumulation principle [J]. Mechanical Research and Application, 2010 (1): 3.) published an SMA linear actuator based on displacement accumulation, which includes a driving element, a frame, a lead screw, a driving plate, and left and right locking nuts. The SMA single action displacement is accumulated by the nut locking method to output force and displacement. The linear actuator driving element is composed of 20 shape memory alloy sheets, which are symmetrically distributed in two groups, each with 10 sheets, one end of which is fixed on the frame and the other end is connected to the middle baffle. By continuously heating and cooling the two groups of alloy sheets alternately and contracting in turn, the middle baffle is driven to push the nut and the lead screw to achieve force and displacement output. The outer periphery of the left and right locking nuts is a spur gear, which is driven by a small gear driven by a motor, as a displacement progression and self-locking with the shaft. Although this drive achieves a large displacement by means of displacement accumulation, it has the following defects: 1. A motor is required to drive the nut to reset, which increases the complexity of the structure and control system; 2. The drive speed is slow by using the displacement accumulation method. Summary of the invention

[0004] The purpose of the present invention is to provide an SMA linear actuator which can better realize linear driving, has a simple structure, and has a large output displacement.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] An SMA linear actuator, comprising:

[0007] The SMA winding mechanism includes an SMA wire, a driving spindle, a spindle pulley mounted on the driving spindle, and a transition pulley block located next to the driving spindle. One end of the SMA wire is wound and fixed on the spindle pulley, and the other end passes through the transition pulley block and is fixed. The SMA wire is also energized.

[0008] Heat dissipation mechanism: It is arranged next to the SMA winding mechanism and is used to dissipate heat for the SMA wire;

[0009] Actuator: includes an inner tube, an outer tube and a connecting end plate, one end of the inner tube is connected to the driving spindle, and the other end is fixedly connected to the connecting end plate, the outer tube itself can be extended and retracted along the driving spindle direction, and one end is fixed, and the other end is fixedly connected to the connecting end plate.

[0010] Furthermore, the SMA winding mechanism also includes a left mounting plate and a right mounting plate, and one end of the driving spindle is rotatably mounted on the left mounting plate, and the other end passes through the right mounting plate and is connected to the inner tube, and a plurality of side plates arranged around the driving spindle are also installed between the left mounting plate and the right mounting plate, and the side plates form a cavity for accommodating the transition pulley group, and the left mounting plate and the side plates are both provided with heat dissipation holes.

[0011] Furthermore, the total length of the SMA wire is greater than 500 mm.

[0012] Furthermore, the transition pulley group includes four pulley shafts arranged in parallel around the driving main shaft, a plurality of main pulleys evenly arranged on the pulley shafts, and a side pulley arranged on the side of the pulley shaft. The end of the SMA wire away from the main shaft pulley passes through the main pulley and the side pulley to form four circles around the driving main shaft and then is fixed.

[0013] Furthermore, the main pulleys are provided with 16 and the side pulleys are provided with 3.

[0014] Furthermore, the heat dissipation mechanism is a heat dissipation fan.

[0015] Furthermore, a transition piece connecting the heat dissipation mechanism and the SMA winding mechanism is provided between the two.

[0016] Furthermore, the ends of the inner tube and the outer tube are fixed to the connecting end plates by screws respectively.

[0017] Furthermore, the inner tube is a Kresling folded tube.

[0018] Furthermore, the installation direction of the inner tube satisfies that: when the SMA wire heats up and contracts, and drives the driving spindle to rotate, the inner tube is twisted and contracted in the positive direction along with the driving spindle, thereby causing the actuator to contract as a whole. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the structure of the driver of the present invention;

[0020] Figure 2It is a structural schematic diagram of the left mounting plate of the present invention;

[0021] Figure 3 It is a schematic diagram of the disassembled SMA winding mechanism of the present invention;

[0022] Figure 4 It is a disassembled schematic diagram of the actuator of the present invention;

[0023] Description of the markings in the figure:

[0024] 1-SMA winding mechanism, 11-SMA wire, 12-driving spindle, 13-spindle pulley, 14-left mounting plate, 15-right mounting plate, 16-side plate, 17-pulley shaft, 18-main pulley, 19-side pulley;

[0025] 2-Heat dissipation mechanism;

[0026] 3-actuator, 31-inner tube, 32-outer tube, 33-connecting end plate;

[0027] 4- Transition piece. DETAILED DESCRIPTION

[0028] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0029] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0030] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] In the following implementation manners or examples, unless otherwise specified, functional components or structures are conventional components or conventional structures used in the art to achieve corresponding functions.

[0032] In order to better realize linear drive, simple structure, large output displacement, etc., the present invention provides an SMA linear drive, the structure of which is shown in FIG. Figure 1 , Figure 3 , Figure 4 As shown, including:

[0033] The SMA winding mechanism 1 includes an SMA wire 11, a driving spindle 12, a spindle pulley 13 mounted on the driving spindle 12, and a transition pulley block located next to the driving spindle 12. One end of the SMA wire 11 is wound and fixed on the spindle pulley 13, and the other end passes through the transition pulley block and is fixed. The SMA wire 11 is also energized.

[0034] Heat dissipation mechanism 2: it is arranged beside the SMA winding mechanism 1 and is used to dissipate heat for the SMA wire 11;

[0035] Actuator 3: includes an inner tube 31, an outer tube 32 and a connecting end plate 33, wherein one end of the inner tube 31 is connected to the driving spindle 12, and the other end is fixedly connected to the connecting end plate 33, and the outer tube 32 itself can be extended and retracted along the driving spindle 12, and one end thereof is fixed, and the other end is fixedly connected to the connecting end plate 33.

[0036] In some specific implementations, please refer to Figure 2 and Figure 3 As shown, the SMA winding mechanism 1 also includes a left mounting plate 14 and a right mounting plate 15, and one end of the driving spindle 12 is rotatably mounted on the left mounting plate 14, and the other end passes through the right mounting plate 15 and is connected to the inner tube 31, and a plurality of side plates 16 arranged around the driving spindle 12 are also installed between the left mounting plate 14 and the right mounting plate 15, and the side plates 16 form a cavity for accommodating the transition pulley set, and heat dissipation holes are installed on both the left mounting plate 14 and the side plates 16.

[0037] In some specific implementations, the total length of the SMA wire 11 is greater than 500 mm.

[0038] In some specific implementations, please refer to Figure 3 As shown, the transition pulley group includes four pulley shafts 17 arranged in parallel around the driving main shaft 12, a plurality of main pulleys 18 evenly arranged on the pulley shafts 17, and a side pulley 19 arranged on the side of the pulley shaft 17. The end of the SMA wire 11 away from the main shaft pulley 13 passes through the main pulley 18 and the side pulley 19 to form four circles around the driving main shaft 12 and then is fixed.

[0039] Furthermore, the main pulleys 18 are provided with 16, and the side pulleys 19 are provided with 3. For details, please refer to Figure 3 As shown, four pulley shafts 17 are defined as a first pulley shaft 17, a second pulley shaft 17, a third pulley shaft 17, and a fourth pulley shaft 17, and 16 main pulleys 18 are divided from right to left into a first group (pulley No. 1, pulley No. 2, pulley No. 3, pulley No. 4), a second group (pulley No. 5, pulley No. 6, pulley No. 7, pulley No. 8), a third group (pulley No. 9, pulley No. 10, pulley No. 11, pulley No. 12), and a fourth group (pulley No. 13, pulley No. 14, pulley No. 15, pulley No. 16) corresponding to the four pulley shafts 17. The three side pulleys 18 are respectively 9 are the first side pulley 19, the second side pulley 19 and the third side pulley 19 respectively, then the SMA line 11 can pass through the No. 1 pulley, the No. 5 pulley, the No. 9 pulley, and the No. 13 pulley in sequence, and then turn through the first side pulley 19, then pass through the No. 14 pulley, the No. 10 pulley, the No. 6 pulley, and the No. 2 pulley, continue to turn through the second side pulley 19, then pass through the No. 3 pulley, the No. 7 pulley, the No. 11 pulley, and the No. 15 pulley, and then continue to turn through the third side pulley 19, and finally pass through the No. 16 pulley, the No. 12 pulley, the No. 8 pulley, and the No. 4 pulley, and then be fixed to the left mounting plate 14 with bolts.

[0040] In some specific implementations, the heat dissipation mechanism 2 is a heat dissipation fan.

[0041] In some specific implementations, a transition piece 4 is further provided between the heat dissipation mechanism 2 and the SMA winding mechanism 1 to connect the two.

[0042] In some specific implementations, please refer to Figure 4 As shown, the ends of the inner tube 31 and the outer tube 32 are fixed to the connecting end plate 33 by screws respectively.

[0043] In some specific embodiments, the inner tube 31 is a Kresling folded tube.

[0044] In some specific embodiments, the installation direction of the inner tube 31 satisfies that: when the SMA wire 11 heats up and shrinks, and drives the driving spindle 12 to rotate, the inner tube 31 twists and shrinks in the positive direction along with the driving spindle 12, thereby shrinking the actuator 3 as a whole.

[0045] The above embodiments may be implemented individually or in any combination of two or more.

[0046] The above implementation is described in more detail below in conjunction with specific examples.

[0047] Embodiment 1:

[0048] This embodiment provides an SMA linear actuator, including a cooling fan, a transition piece 4, an SMA wire 11 winding mechanism and an actuator 3. The SMA winding mechanism 1 includes an SMA wire 11, a driving spindle 12, a spindle pulley 13, a main pulley 18 and a side pulley 19, a left mounting plate 14, a right mounting plate 15 and a side plate 16, wherein the two ends of the SMA wire 11 are respectively fixedly connected to the spindle pulley 13 and the side plate 16, and the SMA wire 11 passes through the main pulley 18 and the side pulley 19 and is wound in the mechanism, and when the SMA wire 11 is heated and contracted, the spindle pulley 13 is pulled to rotate, and the driving spindle 12 is driven to rotate. The actuator 3 is composed of an inner tube 31, an outer tube 32 and a connecting end plate 33, one end of the inner tube 31 is connected to the driving spindle 12 of the SMA winding mechanism 1 by a screw, and the other end is connected to the outer tube 32 by a connecting end plate 33, and the actuator 3 can convert the rotation of the driving spindle 12 into linear motion.

[0049] like Figure 1 As shown, the complete mechanism consists of a cooling fan, a transition piece 4, an SMA winding mechanism 1 and an actuator 3. The SMA wire 11 is fixed at both ends in the winding mechanism through a transition pulley set, and the total winding length is about 500 mm. The ends of the SMA wire 11 are fastened by bolts and connected to the wires. Under the action of external current, the SMA wire 11 contracts, driving the drive spindle 12 to rotate, and then driving one end of the inner tube 31 of the actuator 3 to rotate, and the actuator 3 performs linear motion. When the current passes through the SMA wire 11, a large amount of heat will be generated, which needs to be discharged in time through an external heat dissipation device. The cooling fan is connected to the SMA winding mechanism 1 through the transition piece 4, and continuously pumps gas into the winding mechanism, such as Figure 2 As shown, the left mounting plate 14 is provided with many heat dissipation holes to facilitate the circulation of heat dissipation air. The gas flows out from the heat dissipation holes on the side plate 16 and continuously takes away the heat. By adjusting the current of the SMA wire 11 and the power of the heat dissipation fan, the contraction degree of the SMA wire 11 can be controlled so that the main axis of the SMA winding mechanism 1 rotates to a specific angle.

[0050] Figure 3The figure shows the disassembly diagram of the SMA winding mechanism 1. The SMA winding mechanism 1 is composed of a left mounting plate 14, a right mounting plate 15, four side plates 16, three side pulleys 19, 16 main pulleys 18, a main shaft pulley 13, a driving main shaft 12 and an SMA wire 11. The head end of the SMA wire 11 is wound around the main shaft pulley 13 (pre-wound 1 circle) and fixed by bolts. The SMA wire 11 passes through 16 main pulleys 18 and 3 side pulleys 19, and is wound about 4 circles in the mechanism, with a total length of about more than 500mm, and is finally fixed to the bolts of the side plate 16 with bolts. The bolts are also wound with electric wires while winding the SMA wire 11, so that the SMA wire 11 is energized and heated. The SMA wire 11 contracts under the action of heat, and the SMA wire 11 pre-wound on the main shaft pulley 13 gradually contracts, driving the main shaft pulley 13 to rotate. The driving spindle 12 is connected to the spindle pulley 13 through a key, thereby driving the driving spindle 12 to rotate. The driving spindle 12 is connected to the inner tube 31 of the actuator 3 through a screw, thereby driving one end of the inner tube 31 of the actuator 3 to rotate. When the temperature of the SMA wire 11 decreases under the action of the cooling air, it gradually stretches and gradually winds back on the spindle pulley 13 under the action of the restoring force of the inner tube 31 of the actuator 3. In this way, the mechanism can achieve a cyclic reciprocating motion.

[0051] Figure 4 As shown in the disassembled diagram of the actuator structure, the actuator 3 is composed of an inner tube 31, an outer appearance, and an end plate 33 connected to the inner tube 31. One end of the inner tube 31 is connected to the main shaft of the SMA winding mechanism 1 by screws, and the other end is connected to the end plate of the inner tube 31 by screws. The end plate of the inner tube 31 is connected to one end of the outer tube 32 by screws, thereby realizing the connection between the inner tube 31 and the outer tube 32. The other end of the outer tube 32 is connected to the right mounting plate 15 of the SMA winding mechanism 1 by screws. When the SMA wire 11 contracts and drives the main shaft to rotate, it drives one end of the inner tube 31 to rotate. The other end of the inner tube 31 is connected to the outer tube 32 and does not rotate. At this time, the two end faces of the inner tube 31 rotate relative to each other, the inner tube 31 contracts, and the actuator 3 contracts as a whole. When the temperature of the SMA wire 11 decreases, the inner tube 31 actively extends under the action of its own restoring force, and the actuator 3 extends as a whole, thereby realizing reciprocating linear drive.

[0052] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A SMA linear actuator, characterized in that: include: The SMA winding mechanism includes an SMA wire, a driving spindle, a spindle pulley mounted on the driving spindle, and a transition pulley block located next to the driving spindle. One end of the SMA wire is wound and fixed on the spindle pulley, and the other end passes through the transition pulley block and is fixed. The SMA wire is also energized. Heat dissipation mechanism: It is arranged next to the SMA winding mechanism and is used to dissipate heat for the SMA wire; Actuator: includes an inner tube, an outer tube and a connecting end plate, one end of the inner tube is connected to the driving main shaft, and the other end is fixedly connected to the connecting end plate, the outer tube itself can be extended and retracted along the driving main shaft, and one end is fixed, and the other end is fixedly connected to the connecting end plate.

2. The SMA linear actuator according to claim 1, characterized in that: The SMA winding mechanism also includes a left mounting plate and a right mounting plate, and one end of the driving spindle is rotatably mounted on the left mounting plate, and the other end passes through the right mounting plate and is connected to the inner tube. A plurality of side plates arranged around the driving spindle are also installed between the left mounting plate and the right mounting plate, and the side plates form a cavity for accommodating the transition pulley set, and both the left mounting plate and the side plates are provided with heat dissipation holes.

3. The SMA linear actuator according to claim 1, characterized in that: The total length of the SMA wire is greater than 500 mm.

4. The SMA linear actuator according to claim 1, characterized in that: The transition pulley group includes four pulley shafts arranged in parallel around the driving main shaft, a number of main pulleys evenly arranged on the pulley shafts, and side pulleys arranged on the sides of the pulley shafts. The end of the SMA wire away from the main shaft pulley passes through the main pulley and the side pulley to form four circles around the driving main shaft and then is fixed.

5. The SMA linear actuator according to claim 4, characterized in that: The main pulleys are provided with 16 pieces, and the side pulleys are provided with 3 pieces.

6. The SMA linear actuator according to claim 1, characterized in that: The heat dissipation mechanism is a heat dissipation fan.

7. The SMA linear actuator according to claim 1, characterized in that: A transition piece is also provided between the heat dissipation mechanism and the SMA winding mechanism to connect the two.

8. The SMA linear actuator according to claim 1, characterized in that: The ends of the inner tube and the outer tube are fixed to the connecting end plate by screws respectively.

9. The SMA linear actuator according to claim 1, characterized in that: The inner tube is a Kresling folded tube.

10. The SMA linear actuator according to claim 1 or 9, characterized in that: The installation direction of the inner tube satisfies that when the SMA wire heats up and contracts, and drives the driving spindle to rotate, the inner tube twists and contracts in the positive direction along with the driving spindle, thereby causing the actuator to contract as a whole.

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