JPH0783620B2 - Stepping motor using an actuator driven by a bimorph type piezoelectric ceramic - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor using an actuator having a bimorph type piezoelectric ceramic as a drive source.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In a conventional stepping motor, a plurality of iron pieces are provided on the outer circumference of a rotor with a constant pitch, and a plurality of magnetic poles are provided on the inner circumference of a stator at a constant angle with respect to the iron pieces of the rotor. It is known that the rotor is rotated by a fixed angle by sequentially exciting each magnetic pole by sequentially exciting each magnetic pole and attracting iron pieces. In a stepping motor that rotates the rotor, the magnetic pole and the iron piece do not mechanically engage, for example, when teeth are engaged with each other. Therefore, when the rotor is rotated, the magnetic pole is resisted against its inertial force. It is difficult to surely stop at the position where the iron piece and the iron piece are aligned,
There was a shortcoming of lack of certainty.

Therefore, the applicant of the present application, as a stepping motor having excellent positive motion, rotatably supports a rotor having a large number of teeth on the outer peripheral surface in a cylindrical body, and the tooth on the inner peripheral surface of the body. A plurality of pressing bodies that have engaging portions that engage with each other and that are free to move back and forth in the direction of the center of the rotor are provided with different phases to the teeth of the engaging portions. An actuator that expands and contracts using a laminated piezoelectric ceramic in which a plurality of piezoelectric ceramics whose thickness changes by application is laminated as a drive source is provided corresponding to each pressing body, and each pressing body is moved forward and backward in sequence to We developed a motor that rotates the rotor by a certain angle by pressing the beveled surface of the tooth with the engaging part when moving forward, and filed it as Japanese Patent Application No. 59-51371 (Japanese Patent Publication No. 3-34306). The structure of stepping motor is low Since the rotor is rotated by the mechanical engagement of the pressing body and the pressing body, the above-mentioned accuracy is excellent, and since the piezoelectric ceramic is excellent in high-speed response, the high-frequency pulse voltages whose phases are sequentially shifted are applied to the respective actuators. Since the rotor can be smoothly and continuously rotated by applying the voltage to the actuator, the actuator driven by the laminated piezoelectric ceramic that expands and contracts according to the total change in the thickness of each piezoelectric ceramic has a relatively small amount of change. small,
In order to obtain the stroke required for the pressing body, it is necessary to increase the number of laminated piezoelectric ceramics and increase the total length of the actuator, and the actuator is housed on the outer circumference of the rotor to move the pressing body back and forth toward the center of the rotor. There is a problem that the motor becomes large due to the large space required, and in order to avoid this, the actuator is placed between the pressing body and the body at an angle with respect to the moving direction of the pressing body. A method of driving the pressing body by amplifying the displacement of the actuator by restricting the operating end that engages with the pressing body so as to move freely only in the advancing / retreating direction was also considered, but the structure is complicated. There was a problem that it took time to manufacture, and there was still room for improvement.

The present invention has been completed in view of the above points, and by using an actuator that uses a bimorph type piezoelectric ceramic as a drive source for an actuator that drives a pressing body, the accuracy of the rotor is guaranteed and the rotor To provide a stepping motor that utilizes the excellent characteristics of a stepping motor that uses an actuator that uses a laminated piezoelectric ceramic that enables smooth continuous rotation as described above, and that has a simple structure and can be integrated into a small volume. The purpose is to

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

Reference numeral 1 denotes a body having a center hole 2 and having a narrow tubular shape of a substantially equilateral cross section, which is supported by a pair of legs 3 and 3. In the center hole 2 of the body 1, Cylindrical rotor 4
Are fitted concentrically and are rotatably supported around a horizontal axis, and a large number of isosceles outer peripheral teeth 5 are continuously formed on the outer peripheral surface of the rotor 4 with constant pitches.

At the position corresponding to the center of each side of the triangle on the inner peripheral surface of the body 1, three guide grooves 6 facing the center of the rotor 4 are provided.
A pressing body 7 is formed at intervals of 120 degrees, and a plurality of feed teeth 8 are formed in each guide groove 6 on the surface corresponding to the rotor 4 so as to have the same pitch as the outer peripheral teeth 5. The rotor 4 is fitted so as to move back and forth in the direction of the center, and the positional relationship of these feed teeth 8 with respect to the outer peripheral teeth 5 is based on the feed teeth 8 aligned with the outer peripheral teeth 5 and the other two feed teeth. 8
However, the phase shift with respect to the outer peripheral tooth 5 is sequentially increased counterclockwise by 1/3 pitch, and when the feed dog 8a at the position I is aligned with the outer peripheral tooth 5, the feed at the position II is fed. tooth
8b is out of phase with the 1/3 pitch, and the position III feed dog 8c is out of phase with the outer peripheral tooth 5 in each of the 2/3 pitches.

Actuators 11 for driving the pressing bodies 7 are installed and fixed to the lower surface of each pressing body 7 in the body 1 in a posture along each side of the triangle. As shown in FIG. 2, the actuator 11 uses a bimorph-type piezoelectric ceramic 12 as a driving source, and the bimorph-type piezoelectric ceramic 12 includes magnesium-niobate lead as shown in FIG. It consists of lead titanate binary solution ceramics {(1-X) Pb (Mg _1/3 Nb _2/3 ) O ₃ -PbTiO ₃ } in which X is close to 0.35. On one surface of the elongated piezoelectric ceramic plate 13 having the property to occur,
It has a structure in which a back plate 14 having a small expansion / contraction rate such as a stainless steel plate is laminated and bonded to each other, and when a voltage is applied to the piezoelectric ceramic plate 13, a difference in elongation between the free front surface side and the restrained back surface side is caused. Then, it swells and bends to the surface side, it returns to its original state when the voltage application is removed, the response speed is extremely fast, and it bends an elongated plate-shaped object, so compared to the laminated piezoelectric ceramics. The bimorph type piezoelectric ceramic 12 has a feature that a large amount of displacement can be taken, and the bimorph type piezoelectric ceramic 12 is loaded with the surface upward in an elongated recess 16 formed on the upper surface of the substrate 15, and the rollers 17 and 17 fixed to both ends are provided. The bimorph-type piezoelectric ceramic 12 is fitted and supported in the circular holes 18 and 18 so as to freely rotate around the axis.
An actuator 20 is fitted in the central portion in the longitudinal direction of the piezoelectric ceramic plate 13, and electrodes 40, 40 are provided on both ends of the piezoelectric ceramic plate 13 as shown in FIG.
41 are attached, and these are connected to a power source (not shown) by a lead wire, and by repeatedly energizing and insulating the piezoelectric ceramic plate 13, the bimorph type piezoelectric ceramic 12 has a curve shown by a chain line. And the return to the free state shown by the solid line is repeated, whereby the actuator 20 reciprocates between the chain line position and the solid line position.

The actuator 11 is provided with the actuator 20 corresponding to the lower surface of the pressing body 7 as described above, and the forward movement of the actuator 20 moves the pressing body 7 to the position where the feed dog 8 of the pressing body 7 meshes with the outer peripheral teeth 5 of the rotor 4. An elastic ring (not shown) for returning the pressing body 7 is fitted so as to be inwardly in contact with each pressing body 7.

In addition, the above-mentioned bimorph type piezoelectric ceramic 12 has a fifth
As shown in the figure, two piezoelectric ceramic plates 13 are attached to each other, and one piezoelectric ceramic plate 13 is expanded by applying a voltage by the electrodes 40 and 41, and the other piezoelectric ceramic plate 13 is expanded.
It is also possible to use the one that contracts to change the curvature.

Next, the operation of this embodiment will be described.

As shown in FIG. 1, when the pressing body 7 at the position I is advanced and the feed dog 8a is engaged with the outer peripheral tooth 5, the feed dog is moved.
When 8b energizes the adjacent actuator 11 whose phase is shifted by 1/3 pitch with respect to the outer peripheral tooth 5 and cuts off energization of the actuator 11 at the position I, the pressing body 7 at the position II moves forward and the position I The pressing body 7 of 6 moves backward by the elastic force of the elastic ring, and as described above, the feed dog 8b at the position II is out of phase by 1/3 pitch with respect to the outer peripheral tooth 5, and the tip of the feed tooth 8b is the outer peripheral tooth. Since it corresponds to the clockwise front slope of No. 5, the tooth tip pushes the slope of the outer peripheral tooth 5 in the forward movement of the feed dog 8b to rotate the rotor 4 counterclockwise by 1/3 pitch. In this state, the feed dog 8c adjacent to the position III is out of phase with the outer peripheral tooth 5 by 1/3 pitch, so that the actuator 11 at the position III is continuously energized to feed dog 8c.
By moving the actuator 11 at the position II off and turning the feed dog 8b backward.
1/3 pitch Rotate in the same direction.

As described above, the rotor 4 can be intermittently rotated counterclockwise by 1/3 pitch by repeating energization and interruption in the actuators 11 at the positions I, II, and III in a constant cycle. When the predetermined sending tooth 8 meshes with the outer peripheral tooth 5, if the actuator 11 is kept in the energized state, the rotor 4 can be stopped at an arbitrary rotation angle.

Further, the pressing body 7 is driven by an actuator 11 using a bimorph type piezoelectric ceramic 12, and since the bimorph type piezoelectric ceramic 12 is excellent in high-speed response, the phase is sequentially shifted to the actuator 11. By applying a high-frequency pulse voltage, the rotor 4 can be smoothly and continuously rotated. Further, the bimorph type piezoelectric ceramic 12 is curved so that the plate-shaped one changes its curvature. Since a large amount of change of 20 can be taken, the actuator with a long overall length is used to obtain the stroke required for the pressing body 7 as in the case of using an actuator using a laminated piezoelectric ceramic as a drive source. 4 is installed on the lower surface of the pressing body 7 in the direction of the center of the motor 4, or the size of the motor is increased, or an actuator is attached to the pressing body 7. It is possible to avoid the complication of the structure due to device to be inclined obliquely with respect to the backward direction.

FIG. 4 shows another embodiment of the present invention. In this stepping motor, a body 31 has a central hole 32, and six bulges are formed at intervals of 60 degrees over the entire length of the outer peripheral surface. In the axial direction of the star-shaped cross section in which the portions 33 are radially projected, a long and slender tubular shape is formed.
A rotor 34 formed by continuously forming 35 is rotatably supported around a horizontal axis, and a guide groove 36 facing the center of the rotor 34 is formed over the entire length on the inner peripheral surface of each bulging portion 33. Guide groove 36
A pressing body 37 is formed on the surface corresponding to the rotor 34, in which two feed teeth 38 which face each other and whose phase shift with respect to the outer peripheral teeth 35 sequentially increases counterclockwise by 1/3 pitch are formed.
Is fitted in the rotor 33 so as to move back and forth in the center direction, and the above-mentioned bimorph type piezoelectric ceramics 12 are attached to the lower surface of each pressing body 37.
An actuator 11 having a drive source as a drive source is installed and fixed along the axial direction of the body 31, and the actuator 20 corresponds to the lower surface of the pressing body 37.
The rotor 11 is rotated counterclockwise by repeatedly energizing and blocking the actuators 11 at positions II and V and positions III and VI in a fixed cycle, and sequentially driving the pressing bodies 37 facing each other in the counterclockwise direction. It is possible to rotate the rotor 34 intermittently by 1/3 pitch and to drive the rotor 34 by pressing the outer peripheral teeth 35 of the rotor 34 with the feed teeth 38 of the two pressing bodies 37 facing each other. As well as getting
This has the advantage that no bending moment acts on the rotor 34 when the outer peripheral teeth 35 are pushed.

In each of the above-mentioned embodiments, since the outer peripheral teeth 5 and 35 are in an isosceles triangle and the slopes are formed on both sides, the pressing bodies 7 and 37 are sequentially driven in the clockwise direction contrary to the respective embodiments. Then, the rotors 4 and 34 can be rotated clockwise by 1/3 pitch at a time. However, when it is sufficient to rotate the rotors 4 and 34 in only one direction, the outer peripheral teeth 5 and 35 can be rotated only in one side. It may be serrated with a slope, and
The number of devices of the feed dogs 8 and 38 may be two or more.

As described in detail with reference to the above embodiments, a stepping motor using an actuator having a bimorph type piezoelectric ceramic of the present invention as a driving source has a large number of slopes on one side or both sides. A rotor provided with teeth on its outer peripheral surface is rotatably supported in a cylindrical body, and has an engaging portion for engaging the teeth on the inner peripheral surface of the body, Of a plurality of pressing bodies that can freely move back and forth with different phases of the engaging portions with respect to the teeth, and a back plate with a small expansion / contraction rate such as a metal plate on one surface of an elongated piezoelectric ceramic plate that expands when a voltage is applied. And the curvature changes due to the extension and return of the piezoelectric ceramic plate, or
Piezoelectric ceramic plates, one of which expands and the other of which contracts when a voltage is applied, are attached to each other, and the curvature changes when the piezoelectric ceramic plates expand and contract and are mounted at the center in the longitudinal direction due to the change in the curvature of the bimorph piezoelectric ceramic. An actuator for reciprocating the operated actuator is fixed to the body on the outside of each of the pressing bodies, the actuator corresponds to the outer surface of the pressing body, and a voltage having a phase shift is sequentially applied to each of the actuators. In this way, the pressing body is sequentially advanced and retracted, and when the pressing body is advanced, the engaging portion presses the inclined surface of the tooth to rotate the rotor by a constant angle. However, since the engaging portion of the pressing body, which is out of phase with the teeth of the rotor, directly pushes the inclined surface of the teeth to rotate the rotor. Can be reliably rotated by a fixed angle, and rotation of the rotor is stopped by mechanical engagement between the teeth of the rotor and the engaging portion of the pressing body, so that the rotor can be reliably rotated at any rotation angle. Since each actuator is driven by an actuator that uses a bimorph type piezoelectric ceramic that can be stopped and has excellent high-speed response, a high-frequency pulse voltage with a phase shift is sequentially applied to each actuator. As a result, the rotor can be smoothly and continuously rotated, and the bimorph type piezoelectric ceramic deforms so that the plate-shaped one changes its curvature, and thus the displacement of the actuator can be made large. Therefore, as in the case of using an actuator that uses a laminated piezoelectric ceramic as a drive source, the total length must be long to obtain the stroke required for the pressing body. It is not necessary to mount the actuator on the lower surface of the pressing body toward the center of the rotor or to tilt the actuator obliquely with respect to the reciprocating direction of the pressing body to form a complicated structure. This has the effect of achieving downsizing and simplification of the structure.

[Brief description of drawings]

1 is a partially cutaway front view of an embodiment of the present invention, FIG. 2 is an enlarged sectional view of an actuator, FIG. 3 is a partially enlarged perspective view of a bimorph type piezoelectric ceramic, and FIG. FIG. 5 is a partially cutaway front view of another embodiment, and FIG. 5 is a partially enlarged perspective view of another bimorph type piezoelectric ceramic. 1, 31: Body, 4, 34: Rotor, 5, 35: Peripheral teeth, 7, 3
7: Pressing body, 8, 38: Feed dog, 11: Actuator, 12: Bimorph type piezoelectric ceramic, 13: Piezoelectric ceramic plate, 14:
Back plate, 20: Actuator, 40, 41: Electrode

Claims (2)

[Claims] 1. A rotor for rotatably supporting a rotor having a large number of teeth having inclined surfaces on one side or both sides on an outer peripheral surface thereof, the inner peripheral surface of the body engaging with the teeth. A plurality of pressing bodies having joint portions and free to move back and forth in the center direction of the rotor are provided with different phases of the engaging portions with respect to the teeth, and are elongated piezoelectric ceramics which are extended by applying a voltage. A back plate having a small expansion / contraction ratio such as a metal plate is attached to one surface of the plate, and the piezoelectric ceramic plate is mounted at the central portion in the longitudinal direction due to the change in the curvature of the bimorph type piezoelectric ceramic whose curvature is changed by the extension return. An actuator for reciprocating the actuator is fixed to the body on the outside of each of the pressing bodies, the actuator corresponds to the outer surface of the pressing body, and voltages having a phase shift are sequentially applied to each of the actuators. The bimorph is configured so that the pressing body is sequentially advanced and retracted by the above, and when the pressing body is advanced, the engaging portion presses the inclined surface of the tooth to rotate the rotor by a constant angle. Type stepping motor using an actuator that uses a piezoelectric ceramic as a drive source. 2. A rotor for rotatably supporting a rotor having a large number of teeth having inclined surfaces on one side or both sides on an outer peripheral surface thereof, the inner peripheral surface of the body engaging with the teeth. A plurality of pressing bodies that have a joint portion and are free to move back and forth in the center direction of the rotor are provided with different phases with respect to the teeth of the engaging portion, and one of them is extended by applying a voltage and the other is extended. The piezoelectric ceramic plates that contract
An actuator that reciprocates an actuator mounted in the central portion in the longitudinal direction by the change of the curvature of the bimorph type piezoelectric ceramic whose curvature is changed by the expansion and contraction return of both the piezoelectric ceramic plates is attached to the body outside the pressing bodies. The actuator is fixed to correspond to the outer surface of the pressing body, and the pressing body is sequentially advanced and retracted by applying voltages having a phase shift to each of the actuators, and when the pressing body is advanced. A stepping motor using an actuator using a bimorph type piezoelectric ceramic as a drive source, characterized in that the rotor is rotated by a predetermined angle by pressing the inclined surface of the tooth with the engaging portion.