WO2011037287A1

WO2011037287A1 - Fail safety actuator

Info

Publication number: WO2011037287A1
Application number: PCT/KR2009/005510
Authority: WO
Inventors: 조언정; 김홍선; 조은상; 이창인; 이진우
Original assignee: 한국산업기술대학교산학협력단; 인지컨트롤스주식회사
Priority date: 2009-09-25
Filing date: 2009-09-25
Publication date: 2011-03-31

Abstract

The present invention relates to a fail safety actuator. The fail safety actuator according to the present invention includes: a driver for supplying a driving force; a moving member for moving to a position or returning to an original position by the driving force of the driver so as to transmit the driving force of the driver to a separate device; and a return assembly to be supplied with power from the outside when the driver is not in operation, and operating by heating operations due to the supplied power so as to supply a pressing force to a part of the moving member, thereby returning the moving member to the original position. According to the present invention, it is possible to easily operate the return assembly since the return assembly operates by the power supply. In addition, it is possible to simply construct the return assembly.

Description

Failsafe Actuator

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fail safety actuator, and to a fail safety actuator having a safety function that provides a driving force to a separate mechanism and prevents malfunction in case of failure. In particular, the present invention relates to a failsafe actuator capable of restoring (returning) a moved component to its original state (home position) when some of the moved components are inoperative.

In general, the actuator is a general term for a driving device that uses electricity, hydraulic pressure, compressed air, etc., and generally refers to a device that performs mechanical work using fluid energy. In the field of mechatronics, it refers to an electric motor having some kind of control mechanism or a piston / cylinder mechanism operated by hydraulic or pneumatic pressure. Recently, the development of artificial muscles and micro actuators using new materials has been actively conducted.

In the case of vehicles, an actuator is installed to open and close the valve. As shown in FIG. 1, the actuator is a valve in which the coupler 14 mounted on the rotation shaft 12a of the spur gear 12 is not shown as the spur gear 12 is rotated by the driving motor 10. Rotate At this time, the spur gear 12 receives the driving force of the drive motor 10 through the gear train 16 as shown by the broken line.

Such an actuator is a fail safety actuator in which the spur gear 12 automatically returns to its original position upon failure, and the spur gear 12 is rotated forward as shown in (b) of the drawing. When opening the valve while (CW), the other end 18b of the compression coil spring 18, in which one end 18a is fixed to the base 1, moves as shown by broken lines in (b) of the figure. . When the compression coil spring 18 is inoperative after the forward rotation (CW) of the drive motor 10 due to an error in the control circuit or a failure of the drive motor 10, the other end 18b is drawn by its own elastic force. Return to the original position as shown by the broken line in (b) of FIG. At this time, the spur gear 12 is forced to the reverse rotation (CCW) by the other end portion 18b of the compression coil spring 18 to return to the correct position. That is, the spur gear 12 is rotated in a state before being rotated. Of course, the not shown valve is closed again. Thus, the vehicle can maintain a stable state as the valve is closed.

Here, the above-described compression coil spring 18 has an elastic force of about 6kgcm. In addition, the above-described drive motor 10 is composed of about 12W class and has a torque of about 10kgcm (Torque). Therefore, when the spur gear 12 is rotated forward by the driving force of the drive motor 10, the spur gear 12 always rotates forward while overcoming the elastic force of the compression coil spring 12.

However, such a common fail safety actuator uses a 12W class drive motor 10 as described above so that the spur gear 12 can always overcome the elastic force of the compression coil spring 18, so that excessive power is required. There is a problem that the miniaturization and weight reduction of parts are almost impossible. That is, the general fail-safe actuator has to use a largely formed drive motor 10 to obtain a large torque, not only excessive power is required, but also miniaturization and weight reduction of the component is not possible.

The present invention has been made to solve the above-mentioned conventional problems, and provides a fail-safe actuator provided with a mechanism for returning a moved member to its original position while being operated by a heating action by a power source generated when the driving source is not operated. For that purpose.

In particular, it is an object of the present invention to provide a fail-safe actuator made of a configuration that can be operated through the deformation characteristics of the elastic force and the shape memory alloy.

Another object of the present invention is to provide a fail safety actuator having a structure in which a moving member can minimize power loss.

In addition, another object of the present invention is to provide a fail-safe actuator provided with a mechanical element capable of controlling the rotation angle of a rotationally moving member by intermittently rotating the rotation angle of the rotationally moving member.

A fail safety actuator according to the present invention for achieving the above object is a driver for providing a driving force; A moving member which transfers the driving force of the driver to another device while being moved by the driving force of the driver or returning to its original position; And a return assembly which receives power from the outside as the driver is inoperative and provides a pressing force to a portion of the moving member while returning the moving member to its original position while operating by a heating operation by the supplied power.

The moving member is a spur gear that is rotatably moved by a driving force provided by the driver, has a rotation axis in the center, and is returned to its original position by the return assembly operated by the non-operation of the driver. Can be.

The return assembly is, for example, is wound around the rotating shaft of the spur gear, and has one end forming a fixed end and the other end forming a free end, while deforming to the form in which the other end is stored by the heat generation action by the supplied power. A self-variable torsion spring made of a moving shape memory alloy; And a protrusion for protruding the spur gear and forcibly rotating the spur gear while the other end of the moving self-variable torsion spring is caught and moved together with the other end.

In contrast, the return assembly may include, for example, a protrusion protruding from the spur gear; The spur gear is wound on a rotational axis of the spur gear, and has one end forming a fixed end and the other end movably fixed in a compressed state while forming a free end. The other end of the spur gear is moved by a compressive force as the fixed state is released. A torsion spring for forcibly rotating the spur gear by rotating the projection; The other end of the torsion spring is in close contact with the other end and supports the one end of the other end so as to be movable in a compressed state, and is bent into a memorized form by a heat generating action by the supplied power to maintain the support of the other end. It may be configured to include; a stopper made of a shape memory alloy to release the movement of the other end.

The present invention, it is necessary to further comprise a rotation angle control means for controlling the rotation angle of the spur gear by moving the projection by a set distance.

The rotation angle control means, for example, has a length corresponding to the set rotation angle of the spur gear, the long hole holder for receiving the projection to guide the rotation of the projection; may be configured.

On the other hand, the return assembly is, for example, provided in the spur gear in unison, a male thread having a steep inclination is formed on the outer circumferential surface to rotate with the spur gear; A union nut provided with a female screw threaded to the male screw of the rotary ring to be screwed to the rotary ring; A coil spring elastically supporting the union nut connected to the rotary ring; An anti-rotation member coupled to one side of the union nut supported by the coil spring to prevent rotation of the union nut; Pressing the union nut, one end of which is in close contact with one side of the union nut, the rotation of which is suppressed by the rotation preventing member, is extended in a memorized form by the exothermic action of the supplied power, and the rotation is suppressed. It may be configured to include; self-elastic spring made of a shape memory alloy forcibly rotating the rotary ring screwed with the union nut.

The anti-rotation member may include, for example, a coupling protrusion integrally provided at one end of the self-elastic spring and coupled with a portion of the union nut to prevent rotation of the union nut; It is preferably configured to include; a projection sheet is provided in one side of the union nut, the projection sheet is seated by fitting the coupling projection.

The fail safety actuator according to the present invention as described above, the return assembly is operated by the heat generation action by the power source can easily operate the return assembly, it is possible to simply configure the return assembly.

In addition, when the moving member is composed of a spur gear that rotates in a rotational manner, the driving force of the driver can be prevented from being lost due to the structural characteristics of the gear. Operation is possible.

In addition, when the return assembly is composed of shape memory alloy material self-variable torsion springs and projections, the self-variable torsion springs are deformed only when the driver is not in operation, and the projections are pressed to rotate the spur gears. Since the pressure is not released and does not interfere with the rotation of the spur gear, it is possible to apply a low-power type small driver that dissipates less torque than before, and to miniaturize the product.

In addition, when providing a rotation angle control means made of a long hole holder, it is possible to limit the movement of the projection through the long hole holder, it is possible to precise control.

In addition, when the return assembly is composed of the projection, the torsion spring and the shape memory alloy stopper, only the stopper needs to be made of the shape memory alloy, so as described above, the manufacturing cost is greater than that of manufacturing the self-variable torsion spring with the shape memory alloy. Can be saved.

In addition, when the return assembly is composed of a coil type self-elastic spring consisting of a rotating ring, union nut, coil spring, anti-rotation member, and shape memory alloy, the return characteristics described above are due to the structural characteristics of the coil type self-elastic spring. In addition to providing greater pressure than the assembly, the pressure can be easily adjusted by adjusting the pitch spacing or the number of turns of the self-elastic spring.

Furthermore, when the anti-rotation member is composed of the engaging projection and the groove-like protrusion sheet, the anti-rotation member can be configured very simply.

1 is a longitudinal sectional view and a plan view of a typical fail safety actuator;

2 is an exploded perspective view of a fail safety actuator according to an embodiment of the present invention;

FIG. 3 is a side view of a portion of the failsafe actuator shown in FIG. 2;

4 is a plan view showing the configuration of the return assembly shown in FIG. 3;

5 is a plan view of a return assembly according to another embodiment of the present invention;

6 is a longitudinal cross-sectional view of a return assembly according to another embodiment of the present invention; And

FIG. 7 is a longitudinal sectional view showing an operating state of the return assembly shown in FIG. 6; FIG.

Hereinafter, referring to the fail safety actuator according to an embodiment of the present invention with reference to the accompanying drawings as follows, the accompanying Figure 2 is an exploded perspective view of the fail safety actuator according to an embodiment of the present invention, Figure 3 2 is a side view of the fail safety actuator shown in FIG. 2, and FIG. 4 is a plan view of the return assembly shown in FIG. 3.

2, a fail safety actuator according to an embodiment of the present invention includes a driver (60) for providing a driving force as shown; Rotor 70 and; Contains the return assembly described below.

The driver 60 may be composed of a hydraulic cylinder or a motor as shown. The driver 60 is built in the case 52.

The rotor 70 may be constituted by a moving member that is rotatable. The rotor 70 is preferably composed of a spur gear 72 is coupled to the rotating shaft 72a as shown. The rotor 70 may be provided with an electric gear coupled to the spur gear 72. In this case, the electric gear may be composed of the drive gear 74 and the driven gear 76 and / or middle gear 78 as shown, alternatively, may be composed of only the drive gear (74). Rotor 70 is connected to the coupler (CP) as shown. This coupler CP connects the rotor 70 with a separate device, such as a valve, not shown.

The return assembly may include a self-variable torsion spring 81 as shown and a protrusion 83 to be described later. The self-variable torsion spring 81 is composed of a shape memory alloy, and the other end portion 81b is a shape memory spring whose shape is stored in a bent form as shown by a broken line. That is, the self-variable torsion spring 81 normally maintains the shape of the other end 81b as shown by the solid line, and when the shape is heated and memorized, the other end 81b is bent in the form as shown by the broken line. Is transformed. The self-variable torsion spring 81 is designed to generate an elastic force of about 10 kgcm to 20 kgcm when deformed.

On the other hand, the case 52 is coupled to the cover 54 is provided with a connector 54a on one side as shown. In this case, the case 52 has a gasket GK interposed therebetween as shown in the edge coupled to the cover 54. Thus, the case 52 is hermetically sealed inside.

As shown in the case 54, a circuit board PC and a gear seat GS are embedded therein. The circuit board PC controls the power supplied to the driver 60 described above to drive the driver 60. And the gear seat GS supports the above-mentioned rotation shaft 72a and the

gear shaft

76a, 78a mentioned later.

On the other hand, the above-described driven gear 76 and middle gear 78 are provided with the above-described

gear shafts

76a and 78a in the center, respectively.

Referring to FIG. 3, the spur gear 72 is fixed to the inside of the case 52 in a rotatable state by the rotation shaft 72a as shown. Spur gear 72 is mated with middle gear 78 as shown. The middle gear 78 forms a gear train together with the drive gear 74 fixed to the rotation axis of the driver 60 and the driven gear 76 engaged with the drive gear 74 as shown. Therefore, the spur gear 72 receives the driving force of the driver 60 through the gear train.

The self-variable torsion spring 81 is fitted and fixed to the rotation shaft 72a of the spur gear 72 as shown. As shown in the enlarged view, the self-variable torsion spring 81 is fixed at one end 81a through the protruding portion of the case 52 to form a fixed end, and the other end 81a is free on the case 52. To achieve. The self-variable torsion spring 81 has an electric wire EW connected to one end 81a and the other end 81b, respectively, as shown in an enlarged manner, and receives a positive current and a negative current from the electric wire EW, respectively.

On the other hand, the spur gear 72 is a coupler (CP) is connected to the end of the rotation shaft (72a) as shown. In addition, the spur gear 72 is provided with a projection 83 of the return assembly at the lower portion as shown. In addition, the circuit board PC and the gear sheet GS are embedded in the case 52 in a stacked state as shown.

On the other hand, the case 52 is provided with a long hole holder 94 for receiving the above-described projections 83 as shown. The long hole holder 94 is formed in the form of a long hole in the case 52 as shown enlarged. The long hole holder 94 is a rotation angle control means for controlling the rotation angle of the rotor 70 by moving the received projection 83 only by a set distance as described below. The long hole holder 94 is formed to have a length corresponding to the set rotation angle of the rotor 70, and is formed in an arc shape as shown to enable the movement of the protrusion 83.

Referring to Figures 3 and 4 attached to the operation of the fail-safe actuator according to an embodiment of the present invention configured as described above are as follows.

Referring to FIG. 3, the driver 60 operates the spur gear 72 through the driving gear 74, the driven gear 76, and the middle gear 78 while operating by the power supplied from the circuit board PC. Rotate At this time, the spur gear 72 is driven by the driving force of the driver 60 through the coupler CP provided at the end of the rotation shaft 72a while being rotated forward or reversely about the rotation shaft 72a (CCW). Open and close the not shown valve. Of course, the valve is open when the coupler CP is rotated forward (CW) and closed when the coupler CP is reversed (CCW).

Referring to FIG. 4, the protrusion 83 moves as shown by the solid line when the spur gear 72 rotates forward (CW), and when the spur gear 72 rotates counterclockwise (CCW), the protrusion 83 moves in a broken line. Move as shown. At this time, the self-variable torsion spring 81 is located at the other end 81b as it is shown in the solid line.

The self-variable torsion spring 81 is stopped by a malfunction or failure after the above-mentioned driver 60 is rotated forward (CW), so that the projections 83 are positioned as shown in solid lines. Power is supplied via the wire EW of 81b). Of course, the self-variable torsion spring 81 is deformed into a memorized shape as shown by the broken line while being heated by the power source. At this time, the self-variable torsion spring 81 is deformed and moved as shown by the broken line while deforming the shape as shown by the broken line while pressing the projection 83 with an elastic force of about 10kgcm to 20kgcm. Therefore, the projection 83 moves as shown by the broken line by the pressing force of the self-variable torsion spring 81. In other words, the protrusion 83 transmits the pressing force of the self-variable torsion spring 81 to a part of the spur gear 72.

On the other hand, the spur gear 72 rotates the rotation shaft 72a while being forced to reverse rotation (CCW) by the projection 83 moving as shown by the broken line. That is, the spur gear 72 is reversely rotated by the pressing force of the self-variable torsion spring 81 transmitted through the protrusion 83. At this time, the rotating shaft 72a reversely rotates the above-described coupler CP installed at the end. Thus, the not shown valve is closed by the coupler CP.

On the other hand, the projection 83 moves along the long hole holder 94 when the spur gear 72 rotates. That is, the long hole holder 94 guides the movement of the protrusion 83. The protrusion 83 is fixed to the end of the long hole holder 94. Therefore, the spur gear 72 has a limited rotation angle due to the long hole holder 94.

The failsafe actuator according to the embodiment of the present invention as described above, the return assembly is composed of a shape memory alloy material self-variable torsion spring 81 which is operated by the heat generation action by the power source can easily operate the return assembly. In addition, the return assembly can be easily configured.

In addition, while the self-variable torsion spring 81 of the return assembly is deformed only when the driver 60 is not operated, the protrusion 83 is pressed to rotate the spur gear 72 of the rotor 70, and the protrusion is normally used. Since the pressure of the 83 is not released to hinder the rotation of the spur gear 72, it is possible to apply the low-power type small driver 60 that dissipates less torque than in the related art, and to miniaturize the product.

In addition, when the moving member is constituted by a spur gear 72 which rotates, the driving force of the driver 60 can be prevented from being lost due to the structural characteristics of the gear. Not only can it be delivered completely but also stable driving is possible.

In addition, since the movement of the projection 83 can be restricted through the long hole holder 94 which is a rotation angle control means, precise control is possible.

On the other hand, Figure 5 is a plan view showing a configuration of a return assembly according to another embodiment of the present invention. The return assembly according to this other embodiment is applied to the metal torsion spring 85 is wound on the rotary shaft 72a of the spur gear 72, as shown instead of the above-described self-variable torsion spring 81, this torsion The stopper 87 is provided to support the other end 85b of the spring 85, which is different from the above-described return assembly.

As shown, the return assembly according to another embodiment of the present invention, as shown, one end 85a of the torsion spring 85 is fixed to the protrusion of the case 52, the other end 85b forms a free end. This torsion spring 85 is supported by the stopper 87 as shown in the other end 85b is forcibly bent. That is, the torsion spring 85 is fixed in a compressed state so that the other end portion 85b constituting the free end is caught by the stopper 87 and is movable. The torsion spring 85 is designed to have an elastic force capable of pressing the protrusion 83 of the spur gear 72.

The stopper 87 is formed of a shape deformation alloy, and an enlarged view on the drawing is formed in a plate shape as shown in "1". The stopper 87 is a shape memory element whose shape is stored in a bent form as shown by a broken line in the enlarged view "1", and maintains a vertical state in a straight line as shown by the solid line. The stopper 87 supports one side of the other end 85b side of the torsion spring 85 in a vertical state as shown in the enlarged view "1". The stopper 87 is connected to the upper and lower wires (EW), respectively, as shown in the enlarged view "①".

Return assembly according to another embodiment as described above, when the driver 60 is not operated after the forward rotation (CW), as shown in the enlarged view "①", both ends of the wire (EW) EW The positive and negative currents are supplied respectively. Accordingly, the stopper 87 is heated to release the supporting state of the other end 85b side of the torsion spring 85 while being deformed as shown by the broken line. At this time, the torsion spring 85 presses the protrusion 83 shown by a solid line while the other end 85b is bounced off by the compressed elastic force. Therefore, the projection 83 forcibly rotates the spur gear 72 while moving along the long hole holder 94 as shown by the broken line (CCW). That is, the projection 83 provides the pressing force to the spur gear 72 to reversely rotate the spur gear 72. Of course, the spur gear 72 rotates together with the rotation shaft 72a to close the valve (not shown) through the rotation shaft 72a and the coupler CP (not shown).

On the other hand, the above-mentioned stopper 87 may be provided with a curved surface 87a at the end of one side facing the other end 85b of the torsion spring 85 as shown in the enlarged view "②" in the drawing. . The curved surface 87a smoothly guides the other end 85b of the torsion spring 85 to the protrusion 83 by the shape characteristic of the stopper 87 when the shape is changed.

In addition, the stopper 87 may be provided with a spring seating groove 87b as shown when the curved surface 87a is formed. The spring seating groove 87b stably restrains the other end 85b of the torsion spring 85 when the stopper 87 is undeformed.

The fail safety actuator according to another embodiment as described above is manufactured only by the shape memory alloy stopper 87 can significantly reduce the manufacturing cost than the above-described embodiment.

On the other hand, Figure 6 attached is a longitudinal cross-sectional view of a return assembly according to another embodiment of the present invention, Figure 7 is a longitudinal cross-sectional view showing an operating state of the return assembly shown in FIG.

Referring to FIG. 6, a return assembly according to another embodiment includes a rotating ring 88 as shown; Union nut 89; Coil springs CS; Self-elastic spring 89b and; The anti-rotation member described below is configured to include a difference from the above-described embodiments. Therefore, only these differences are explained as follows.

As shown by welding or bolting, the rotary ring 88 has one end connected to the spur gear 72 of the rotor 70 in unison. The rotary ring 88 is formed with a male screw 88a having a steep slope on the outer circumferential surface as shown. At this time, the male screw 88a has a steep slope of about 40 ° to 65 °. This male screw 88a is composed of one or two lines. That is, the rotary ring 88 is a single row screw or two rows of screws.

The union nut 89 has a female screw 89a which is screwed with the aforementioned male screw 88a on the inner circumferential surface as shown. The union nut 89 has one end fitted to the other end of the rotary ring 88 slightly. At this time, the female screw (89a) forms a slightly screwed state with the male screw (88). Therefore, the union nut 89 is connected to the rotary ring 88 in a state capable of screwing the rotary ring 88.

Coil spring CS is fitted to the rotary ring 88 in an expanded state as shown. The coil spring CS elastically supports one end of the union nut 89 as shown. Therefore, the union nut 89 does not move (raise) along the rotation ring 88 due to the coil spring CS.

Self-elastic spring 89b is formed in the form of a coil as shown. The self-elastic spring 89b is made of a shape memory alloy, and is compressed as shown after being processed to store the expanded state. Thus, the self-elastic spring 89b remains compressed as shown normally.

The self-elastic spring 89b supports one side of the union nut 89 in a compressed state as shown. At this time, one end of the self-elastic spring (89b) is in close contact with one side of the union nut (89).

As shown in the self-elastic spring 89b, one end and the other end of the wire EW are connected to each other. The wire EW applies positive and negative currents to both ends of the self-elastic spring 89b when the driver 60 is not operated.

On the other hand, the anti-rotation member described above, for example, the engaging projection (89p) integrally connected to one end of the self-elastic spring (89b) and; It is provided on one side of the union nut (89) is a projection sheet of the groove (89 ') shape is coupled to the engaging projection (89p) can be configured;

The coupling protrusion 89p may use a metal plate in the form of a block as shown in an enlarged manner. However, the coupling protrusion 89p may be formed by bending one end of the self-elastic spring 89b, as shown. The formation of the coupling protrusion 89p is easily understood by those skilled in the art, and thus a detailed description thereof will be omitted.

The coupling protrusion 89p is fitted into the groove 89 'provided in the union nut 89 to be coupled with the union nut 89 as shown in an enlarged view. The coupling protrusion 89b is coupled to the groove 89 'to prevent rotation of the union nut 89. That is, the union nut (89) is engaged with the engaging projection (89p) in the groove (89 ') of one side, the rotation is prevented.

Such rotation preventing member is provided with a rod or rail guider GD fitted vertically to the outer circumferential surface of the union nut 89 inside the case 52 as shown by the broken line, so that the union nut ( 89) may be configured to prevent rotation. That is, since the union nut 89 is fitted with a rod or rail guider GD on its outer circumferential surface, rotation is prevented.

Referring to FIG. 7, the self-elastic spring 89b is deformed into a stored shape while being extended as shown when power is supplied from the wire EW by the non-operation of the driver 60 not shown. The self-elastic spring (89b) is extended to press the union nut (89). At this time, the union nut (89) is not rotated due to the engaging projection (89p) fitted in the groove (89 ') as shown in enlargement moves along the rotary ring (88). Of course, the union nut 89 is raised while compressing the coil spring (CS) as shown.

The rotary ring 88 is rotated due to the male screw 88a coupled with the female screw 89a of the union nut 89 as the union nut 89 rises. That is, the rotary ring 88 is rotated because the female screw (89a) is forcibly screwed to the male screw (88a) by the lifting force of the union nut (89). At this time, the female screw (89a) and the male screw (89a) can be screwed together is formed as a steep slope. Accordingly, the rotary ring 88 rotates to reverse the spur gear 72 rotated forward by the driver 60 to its original position.

Fail safety actuator according to another embodiment as described above, because the self-elastic spring (89b) made of a shape memory alloy is formed in the form of a coil can not only provide greater pressure (elastic force) than the above-described embodiment, The pressure (elastic force) can be easily adjusted by adjusting the pitch interval and the number of windings.

Fail safety actuator according to the present invention can be applied to the vehicle as described above, otherwise it can be installed in various industrial devices to enable safe operation of the industrial device. In particular, it is possible to enable safe driving of a driving device such as a motor or a cylinder.

Claims

In an actuator having a failsafe function,

A driver providing a driving force;

A moving member for transferring the driving force of the driver to another device while being moved by the driving force of the driver or returning to its original position; And

A return assembly for returning the moving member to its original position by supplying a pressing force to a portion of the moving member while receiving power from the outside as the driver is not operated and operating by a heating action by the supplied power. Actuator.
The method of claim 1, wherein the moving member,

A spur gear 72 which is rotatably moved by a driving force provided by the driver, has a rotation axis 72a at the center thereof, and is returned to its original position by the return assembly operated by the non-operation of the driver; The failsafe actuator characterized by the above-mentioned.
The method of claim 2, wherein the return assembly,

It is wound on the rotation shaft 72a of the spur gear 72, and has one end portion 81a that forms a fixed end and the other end portion 81b that forms a free end. A self-variable torsion spring 81 made of a shape memory alloy which is moved while deforming to a shape in which 81b) is stored; And

Protrudingly formed on the spur gear 72, the other end 81b of the moving self-variable torsion spring 81 is caught, and the spur gear 72 is forcibly rotated while moving together with the other end 81b. A fail safety actuator comprising a;
The method of claim 2, wherein the return assembly,

A protrusion 83 protruding from the spur gear 72;

It is wound on the rotary shaft 72a of the spur gear 72, and has one end portion 85a constituting a fixed end and the other end portion 85b movably fixed in a compressed state while forming a free end. A torsion spring 85 forcibly rotating the spur gear 72 by rotating the protrusion 83 while moving by the compression force as the fixed state of the 85b) is released; And

The other end (85b) is in close contact with the other end (85b) of the torsion spring (85) while holding one side of the other end (85b) to fix the other end (85b) to be moved in a compressed state, by a heat generating action by the power supplied And a stopper (87) made of a shape memory alloy that allows the movement of the other end (85b) by releasing the support state of the other end (85b) while being bent in a memorized form.
The method according to claim 3 or 4,

Rotation angle control means for controlling the rotation angle of the spur gear 72 by moving the protrusion 83 by a predetermined distance, further comprising:

The rotation angle control means,

And a length holder corresponding to a set rotation angle of the spur gear 72, and a long hole holder 94 for receiving the protrusion 93 and guiding rotation of the protrusion 83.
The method of claim 2, wherein the return assembly,

Rotating ring 88 is provided in the spur gear 72 at one time, the male screw 88a having a steep inclination is formed on the outer circumferential surface and rotates with the spur gear 72;

Union nut (89) is provided with a female screw (89a) for screwing the male screw (88a) of the rotary ring 88 is connected to the rotating ring 88 in a state capable of screwing;

A coil spring (CS) elastically supporting the union nut (89) connected to the rotary ring (88);

A rotation preventing member coupled to one side of the union nut 89 that is elastically supported by the coil spring CS to prevent rotation of the union nut 89; And

Union nut which is one side of the union nut (89) in which the rotation is suppressed by the rotation preventing member is in a compressed state and the one end is in close contact with each other, and the rotation is suppressed while being elongated in a memorized form by the heating action of the supplied power ( 89. A fail-safe actuator comprising: a self-elastic spring (89b) formed of a shape memory alloy for forcibly rotating the rotary ring (88) screwed with the union nut (89).
The method of claim 6, wherein the rotation preventing member,

A coupling protrusion (89p) integrally provided at one end of the self-elastic spring (89b) and coupled with a portion of the union nut (89) to prevent rotation of the union nut (89); And

And a projection sheet provided on one side of the union nut 89 in a groove shape and seated with the coupling protrusion 89p inserted therein.