JP2005207409A - Rotary actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotary actuator of a simple structure, quick operation speed and high reliability. <P>SOLUTION: This rotary actuator is provided with a hollow cylindrical frame 1, a rotary shaft 2 rotatably supported at a center part of the frame, and a shape memory alloy coil 5, and is provided with a flywheel 3 provided coaxially with the rotary shaft, a handle 4 provided on a position shifting from the axis of a rotary shaft at a side surface of the flywheel, at least three shape memory alloy coils 5 fixed to the handle at one end and fixed to the frame at the other end, and lead wire 6 applying voltage to the shape memory alloy coils. The handle is made revolve around the rotary shaft by switching energization to the shape memory alloy coils sequentially. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a rotary actuator using a shape memory alloy that continuously rotates in both forward and reverse directions.

Examples of conventional rotary actuators using shape memory alloys are as follows.
The first has a structure as shown in FIG. 10 (see, for example, Patent Document 1).
In the figure, 1 is a hollow cylindrical frame, 2 is a rotating shaft, 8 is a DC power source, 11 is a current collecting member, 12 is a ratchet gear, 13 is a spiral spring, 14 is an outer end, 15 is an inner end, 16 Is a ratchet claw, and 17 is a switching circuit.
The rotating shaft 2 is supported in the frame 1 via a bearing (not shown). The ratchet gear 12 is fixed to the rotating shaft 2. The spiral spring 13 is made of a shape memory alloy having two directions and is assembled so as to surround the ratchet gear 12. The outer end portion 14 is fixed to the inside of the frame 1, and a ratchet claw 16 is fixed to the inner end portion 15 so as to mesh with the ratchet gear 12. The DC power source 8 heats the spiral spring 13, and the negative side is connected via a current collecting member 11 that slides on the rotary shaft 2, and the positive side is connected to a switching circuit 17. The output of the switching circuit 17 is connected to the outer end 14 of the spiral spring 13 so that a pulsed current flows through the spiral spring 13 by PWM control. The bi-directional shape memory alloy has a property of performing a reversible operation that elongates when heated and returns to its original length when cooled.
With this configuration, when a pulsed current is passed from the DC power supply 8 to the spiral spring 13 via the switching circuit 17, the spiral spring 13 is heated and stretched, and accordingly, is fixed to the inner end 15 of the spiral spring 13. The ratchet pawl 16 thus moved moves in the direction in which the spiral spring 13 is rewound, and the ratchet gear 12 engaged with the ratchet pawl 16 is rotated counterclockwise in the drawing. Next, when the current becomes 0 level, the bi-directional spiral spring 13 contracts due to natural cooling, and the ratchet pawl 16 moves in the winding direction, but the ratchet pawl 16 moves to the outer periphery of the ratchet gear 12. Is returned to its original position and meshed with the ratchet gear 12 at that position. Since this operation is repeated by supplying a pulsed current to the spiral spring 13,
The ratchet gear 12 rotates continuously in one direction, and the rotary shaft 2 to which the ratchet gear 12 is fixed also rotates continuously in one direction.
The second one has a mechanical changeover switch that changes depending on the rotation position, and continuously rotates by switching the current-heating of the shape memory alloy (see Patent Document 2).
As described above, the conventional shape memory alloy actuator has a structure in which energization to the shape memory alloy is controlled by including a current collecting member that slides mechanically and a change-over switch that uses a mechanical contact. Yes.
JP-A-9-268969 (page 3, FIG. 1) JP2001-304096 (6th page, FIG. 1)

However, the conventional shape memory alloy actuator has a structure that includes a mechanically slidable ratchet gear, a current collecting member, and a changeover switch using a mechanical contact, so that the structure becomes complicated and the operation speed is slow. there were. There is also a problem that the contact reliability with respect to energization of the mechanical sliding portion is low.
Therefore, the present invention has been made in view of such problems, and by eliminating the mechanically slidable current collecting member and the changeover switch by mechanical contact, the structure is extremely simple and the operation speed is high. An object is to provide a rotary actuator that is fast and reliable.

In order to solve the above problems, the present invention is configured as follows.
According to a first aspect of the present invention, there is provided a rotary actuator provided with a hollow cylindrical frame, a rotary shaft rotatably supported at a central portion of the frame, and a shape memory alloy coil. A flywheel provided concentrically, a handle provided on a side surface of the flywheel at a position eccentric from the axis of the rotary shaft, and at least three of which one end is fixed to the handle and the other end is fixed to the frame A plurality of shape memory alloy coils, and voltage supply lead wires connected to one end and the other end of the shape memory alloy coil, respectively, and by sequentially switching energization to the shape memory alloy coil, A revolving motion is performed around the rotation axis.
According to a second aspect of the present invention, there is provided a rotary actuator including a hollow cylindrical frame, a rotary shaft rotatably supported at a center portion of the frame, and a shape memory alloy coil. A concentric flywheel, a permanent magnet concentrically provided on the rotating shaft, a handle provided on a side surface of the flywheel at a position eccentric from the axis of the rotating shaft, and one end of the handle At least three shape memory alloy coils with the other end fixed to the frame, voltage supply lead wires connected to one end and the other end of the shape memory alloy coil, and the permanent inside the frame A rotational position of a rotary shaft obtained from the permanent magnet and the Hall element for energizing the shape memory alloy coil. By switching sequentially in accordance with the Patent, it is intended to revolve the handle about said rotary shaft.
According to a third aspect of the present invention, the means for switching energization to the shape memory alloy coil is an energization control circuit using a semiconductor element.
According to a fourth aspect of the present invention, the lead wire fixed to the handle is coiled.

According to the first aspect of the present invention, since the shape memory alloy coil is provided on the handle provided on the side surface of the flywheel fixed to the rotating shaft, there is no mechanically slidable current collecting member or mechanical contact, and the structure However, it is possible to obtain a rotary actuator that is extremely simple, has a high operation speed, and high reliability.
According to the second aspect of the present invention, since the permanent magnet and the Hall element are provided, the energization to the shape memory alloy coil can be sequentially switched in accordance with the rotational position signal of the rotating shaft. It can be ensured and torque can be generated stably.
According to the third aspect of the present invention, since the energization control circuit is configured using the semiconductor element as the energization switching means for the shape memory alloy coil, the reliability of the rotational operation can be extremely increased. In addition, since the energization pattern to the shape memory alloy can be freely performed, it is possible to realize intermittent rotation motion, both forward and reverse continuous rotation motion, and the like.
According to the fourth aspect of the present invention, since the lead wire fixed to the handle is coiled, there is no contact failure and the reliability of the rotational operation can be extremely increased.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a front sectional view showing a rotary actuator using the shape memory alloy of the present invention, and FIG. 2 is a side sectional view. In the figure, 1 is a hollow cylindrical frame, 2 is a rotating shaft, 3 is a flywheel, 4 is a handle, 5 is a shape memory alloy coil, 6 is a lead wire, and 7 is a bearing.
The rotary shaft 2 is rotatably supported inside the frame 1 by a bearing 7. The flywheel 3 is fixed with the rotation shaft 2 and the rotation center being the same, and the handle 4 is rotatably installed on the side surface of the flywheel 3 via a bearing 7 at a position eccentric from the rotation center. The shape memory alloy coil 5 includes a U-phase coil 51, a V-phase coil 52, and a W-phase coil 53, and uses a type that contracts when energized and heated. One end is connected to the handle 4 at one location, and the other end is fixed to the inner peripheral surface of the frame 1. The lead wire 6 is connected to the handle 4 in which the ends of the shape memory alloy are gathered and the other ends of the respective shape memory alloy coils.
A drive circuit for the rotary actuator of the present invention is shown in FIG. In the figure, 5, 51, 52 and 53 are shape memory alloy coils, 8 is a DC power supply, 9 is an energization control circuit, and 10 is a semiconductor element.
One end of the shape memory alloy coil 5 is connected together by a handle 4 and is connected to a positive pole of a DC power source through a lead wire 6. The other end of the shape memory alloy coil 5 is connected to the semiconductor element 10 through a lead wire 6. The other end of each semiconductor element 10 is connected to the negative pole of the DC power supply. The control terminals of the semiconductor element 10 are connected to the energization control circuit 9 respectively.

Next, the operation of the rotary actuator of the present invention will be described.
FIG. 4 is an explanatory view showing the operation of the shape memory alloy actuator according to the present invention, and FIG. 5 is an explanatory view showing an energization pattern to each shape memory alloy. Reference numerals (a) to (f) in FIGS. 4 and 5 indicate the energized state and correspond to each other.
First, in the energized state (a), only the U-phase coil 51 is energized and the V-phase coil 52 and the W-phase coil 53 are energized OFF. Therefore, only the U-phase coil 51 is energized and heated to contract, the handle 4 is drawn toward the U-phase coil 51 side, and the V-phase coil 52 and the W-phase coil 53 are expanded because the handle 4 moves.
Next, when the energized state (b) is entered, in addition to energizing the U-phase coil 51, the V-phase coil 52 is energized, and the V-phase coil 52 is also energized and heated to contract. Since the three coils U to W have the same characteristics and length, the contraction force of the U-phase coil 51 and the V-phase coil 52 is the same, and the handle 4 is connected to the U-phase coil 51 and the V-phase from the U-phase coil 51 side. It moves to an intermediate position of the phase coil 52.
Next, when the energized state (c) is entered, the U-phase coil 51 is energized OFF and only the V-phase coil 52 is energized ON. Therefore, the contraction force of the U-phase coil 51 is lost, and only the V-phase coil 52 has the contraction force. Then, the handle 4 moves to the V-phase coil 52 side, and the U-phase coil 51 and the W-phase coil 53 are expanded as the handle 4 moves. As described above, according to the energized state (a) to the energized state (c), the handle 4 is positioned in the order of the U-phase coil 51 side, the intermediate position between the U-phase coil 51 and the V-phase coil 52, and the V-phase coil 52 side. Moving. At this time, since the handle 4 is attached to the side surface of the flywheel 3 whose rotation center coincides with the rotation shaft 2, the handle 4 moves on a circular orbit centering on the rotation shaft 2.
Similarly, by switching the energized state from (d) → (e) → (f), the handle 4 revolves on a circular orbit about the rotating shaft 2. Since the handle 4 is attached to the side surface of the flywheel 3, the flywheel 3 also rotates around the rotation axis 2. Since the flywheel 3 is fixed with the rotation axis 2 being the same as the rotation center, the rotation shaft 2 also rotates about itself as the rotation center. As described above, the rotational motion can be obtained by utilizing the linear contraction motion of the shape memory alloy. Moreover, since it returns to the same position as the first by the said electricity supply state (a)->(f)-> (a), a continuous rotational motion can be obtained by repeating this electricity supply pattern below.
Since the handle 4 is rotatably attached to the side surface of the flywheel 3 via a bearing 7, it makes a revolving motion around the center of the rotating shaft 2, but the handle 4 itself does not rotate. Therefore, the shape memory alloy coil does not get entangled around the handle 4 and does not break.
Also, the energization state is reverse to the above by changing the pattern (a) → (f) → (e) → (d) → (c) → (b) → (a) in the reverse pattern. The continuous rotational motion of can be obtained.

By controlling the semiconductor element 10 with the energization pattern as described above from the energization control circuit 9, each shape memory alloy coil can be energized and heated with the energization pattern as described above. A continuous rotational motion in both reverse directions can be obtained. Further, since the energization switching is performed by the semiconductor element 10, the operation speed can be increased and the reliability can be increased since the switch is not a mechanical contact switch.
Further, by using a bi-directional shape memory alloy as the shape memory alloy coil, the operating speed can be extremely increased.
In the above embodiment, the case where the number of shape memory alloy coils is three is shown. However, the present invention is not limited to the case where the number of shape memory alloys is three, but can be implemented even when the number is four or more. is there.

A second embodiment of the present invention is shown in FIG. FIG. 6 is a front sectional view of the rotary actuator, and FIG. 7 is a side sectional view. In the figure, 18 is a permanent magnet and 19 is a Hall element. The other reference numerals are the same as those in the first embodiment, and a description thereof will be omitted. This embodiment is different from the first embodiment in that a permanent magnet 18 and a hall element 19 are provided. FIG. 6 shows a front sectional view at the position of the permanent magnet 18, and the front sectional view at the position of the shape memory alloy coil 5 is exactly the same as FIG.
The permanent magnet 18 is fixed with the rotation axis 2 being the same as the rotation center, and the Hall element 19 is fixed to the inner peripheral surface of the frame 1 so as to face the permanent magnet 18. Power is supplied from the lead wire for signal output, and a signal can be output to the outside by a lead wire for signal output (not shown).
A drive circuit for the rotary actuator of the present invention is shown in FIG. In the figure, reference numerals 19, 191, 192 and 193 denote Hall elements. The outputs of the three Hall elements 191, 192, 193 are connected to the energization control circuit 9, respectively.

Next, the operation of the rotary actuator of this embodiment will be described.
FIG. 9 is an explanatory diagram showing energization patterns to each shape memory alloy coil. The diagram showing the operation of the present invention is the same as FIG. Reference numerals (a) to (f) in FIG. 4 and FIG. 9 indicate the energized state and correspond to each other.
The invention of the second embodiment is different from the invention of the first embodiment in that the energization timing to the shape memory alloy coil 5 is switched according to the rotation position of the rotation shaft, and the rotation position of the rotation shaft. Is obtained by the permanent magnet 18 and the Hall element 19.
The Hall element 19 outputs a sinusoidal signal due to the strength of the magnetic flux from the permanent magnet 18. The signal waveform of the Hall element shown in FIG. 9 shows the waveform after the shaping process inside the energization control circuit 9, and is shaped into a rectangular wave.
As shown in FIG. 9, in the invention of the second embodiment, the timing of energizing each shape memory alloy coil 5 is executed in synchronization with the output signal of the Hall element 19 corresponding to each shape memory alloy coil 5. Since the operation of obtaining the rotational motion using the linear contraction motion of the shape memory alloy is the same as that of the first embodiment, the description thereof is omitted.
By controlling the semiconductor element 10 with the energization pattern and energization timing as described above from the energization control circuit 9, it is possible to perform energization heating of each shape memory alloy coil with the energization pattern as described above. Thus, continuous rotational motion in both forward and reverse directions can be obtained. Further, since the energization switching is performed by the semiconductor element 10, the operation speed can be increased and the reliability can be increased since the switch is not a mechanical contact switch.
In addition, since a permanent magnet and Hall element are provided, the energization to the shape memory alloy coil can be sequentially switched according to the rotational position signal of the rotating shaft, so that the operation at the start of operation can be ensured and the torque can be stabilized. Can be generated.
In the above embodiment, the case where the number of poles of the permanent magnet is 2 and the number of Hall elements is 3 is shown. However, the present invention is not limited to the case where the number of poles of the permanent magnet is 2, and It goes without saying that the present invention can be implemented not only in the case where the number is three but also in other cases.

  The present invention is an actuator using a shape memory alloy, and has a small size, a simple structure, a high operation speed, and high reliability. Therefore, the present invention can be applied to a drive actuator such as a micromachine.

Front sectional view of a rotary actuator showing an embodiment of the present invention Side sectional view of a rotary actuator showing an embodiment of the present invention The conceptual diagram which shows the drive circuit of the shape memory alloy actuator of this invention Schematic diagram showing the operation of the rotary actuator of the present invention Explanatory drawing which shows the electricity supply pattern of the rotary actuator of this invention Front sectional view of a rotary actuator showing a second embodiment of the present invention Side sectional view of a rotary actuator showing a second embodiment of the present invention The conceptual diagram which shows the drive circuit of the rotary actuator which shows 2nd Example of this invention. Explanatory drawing which shows the electricity supply pattern of the rotary actuator which shows 2nd Example of this invention. Front sectional view showing a conventional shape memory alloy actuator

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Frame 2 Rotating shaft 3 Flywheel 4 Handle 5 Shape memory alloy coil 6 Lead wire 7 Bearing 8 DC power supply 9 Current supply control circuit 10 Semiconductor element 11 Current collecting member 12 Ratchet gear 13 Spiral spring 14 Outer end 15 Inner end 16 Ratchet Claw 17 Switching circuit 18 Permanent magnet 19, 191, 192, 193 Hall element

Claims (4)

In a rotary actuator provided with a hollow cylindrical frame, a rotary shaft rotatably supported at the center of the frame, and a shape memory alloy coil,
A flywheel concentrically provided on the rotating shaft, a handle provided on a side surface of the flywheel at a position eccentric from the axis of the rotating shaft, one end of the handle fixed to the handle, and the other end fixed to the frame At least three shape memory alloy coils that are fixed, and voltage supply lead wires connected to one end and the other end of the shape memory alloy coil, respectively, by sequentially switching energization to the shape memory alloy coil A rotary actuator characterized in that the handle is caused to revolve around the rotation axis. In a rotary actuator provided with a hollow cylindrical frame, a rotary shaft rotatably supported at the center of the frame, and a shape memory alloy coil,
A flywheel concentrically provided on the rotary shaft, a permanent magnet provided concentrically on the rotary shaft, a handle provided on a side surface of the flywheel at a position eccentric from the axis of the rotary shaft, and the handle At least three shape memory alloy coils having one end fixed to the frame and the other end fixed to the frame, voltage supply lead wires respectively connected to one end and the other end of the shape memory alloy coil, and the frame A Hall element provided at a position facing the permanent magnet on the inner side, and by sequentially switching energization to the shape memory alloy coil in accordance with a rotational position signal of a rotating shaft obtained from the permanent magnet and the Hall element A rotary actuator characterized in that the handle is caused to revolve around the rotation axis.   3. The rotary actuator according to claim 1, wherein the means for switching energization to the shape memory alloy coil is an energization control circuit using a semiconductor element.   The rotary actuator according to any one of claims 1 to 3, wherein the lead wire fixed to the handle has a coil shape.

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