JP2636334B2 - Laminated ultrasonic motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention (1) Industrial Application Field The present invention connects a plurality of motor units to a common output shaft, and connects the output shaft by operating at least one motor unit. The present invention relates to an ultrasonic motor that can be driven to rotate.

(2) Conventional technology Since equipment mounted on aircraft, rockets, satellites, etc. requires a high degree of reliability, a fail-safe mechanism is provided to prevent a fatal accident when a trouble occurs. Have been.

For example, in an electric motor used as a drive source of various devices, a common output shaft is driven by a plurality of motors at the same time, or an output shaft is driven by one motor and another motor is put on standby for backup. This achieves fail-safe.

(3) Problems to be Solved by the Invention However, if a plurality of motors are mounted in order to realize fail-safe, not only a large space for mounting the motors is required, but also the weight is inevitably increased. Problems arise. For this reason, for aerospace equipment in which small size and light weight are extremely important requirements, the appearance of a compact motor having a fail-safe mechanism has been desired.

The present invention has been made in view of the above-described circumstances, and provides a laminated ultrasonic motor having a small and light weight and a fail-safe mechanism by accommodating a plurality of motor units in one casing. Subject.

B. Configuration of the Invention (1) Means for Solving the Problems In order to solve the above problems, the present invention provides a plurality of motor units stacked and housed inside a cylindrical casing to drive a common output shaft. A laminated ultrasonic motor, wherein each of the motor units includes a stator having a large number of piezoelectric elements disposed on an outer periphery thereof, a rotor having an internal gear and pressed against the stator via a pressing means, and a center of the casing. A sun gear rotatably supported by the motor unit, and a planetary gear meshing with the sun gear and the internal gear. The planetary gears of the adjacent motor units are rotatable relative to each other and support a common revolution. The motor units in the final stage are connected sequentially by alternately using the connecting shaft and an intermediate shaft that integrally supports the sun gears of adjacent motor units. A planetary gear or the sun gear, characterized in that coupled to the output shaft.

(2) Operation According to the present invention having the above-described configuration, the stator is caused to generate ultrasonic vibration by energizing the piezoelectric element, and the rotor pressed against the stator by the pressing means is rotationally driven. Then, the planetary gear meshing with the internal gear formed on this rotor revolves around the sun gear while rotating,
The revolving motion of the planetary gear is transmitted to the planetary gear of the next motor unit via the connecting shaft. When the planetary gear of the next-stage motor unit revolves in this way, the sun gear meshing with the planetary gear rotates, and the rotation is transmitted to the sun gear of the next-stage motor unit via the intermediate shaft, and the sun gear is rotated. The planetary gear that meshes with the gear revolves. In this way, the driving force of one motor unit is finally transmitted to the output shaft via the next and subsequent motor units. At that time, when the intermediate stage motor unit is driven, the driving force is reduced. The power is transmitted to the output shaft while being superimposed on the driving force. Therefore, if at least one of the plurality of motor units operates, the output shaft is driven to rotate, and the rotational speed of the output shaft increases as the number of operating motor units increases.

(3) Example Hereinafter, an example of the present invention will be described with reference to the drawings.

1 to 5 show an embodiment of the laminated ultrasonic motor according to the present invention. FIG. 1 is a longitudinal sectional view, FIG. 2 is an enlarged view of a part II in FIG. 1, and FIG. 1 is a sectional view taken along line III-III, FIG. 4 is a sectional view taken along line IV-IV in FIG. 1, and FIG. 5 is a sectional view taken along line VV in FIG. In the following description, the suffixes L, M, and U correspond to the lower, middle, and upper motor units, respectively.

As shown in FIG. 1, the laminated ultrasonic motor includes a cylindrical casing 1, and an output shaft 4 having a drive plate 3 at a lower end at the center of a cover plate 2 covering an upper surface thereof is provided with a ball bearing 5 It is rotatably supported by. In the casing 1, three motor units 6 each having a well-known traveling wave type ultrasonic motor are provided.
L, 6M, and 6U are housed in a vertically stacked state.

As is clear from FIGS. 1 and 3, the lower motor unit 6L is provided with a ring which is prevented from rotating by engaging grooves 4a formed in the vertical direction at four locations on the inner periphery of the casing 1. A ring-shaped stator 8L made of an elastic material is fixed to the upper surface of the support plate 7L with screws 9. Further, on the upper surface of the stator 8L, a rotor 11L having an internal gear 10L (see FIG. 3) formed on the inner periphery is mounted. Three planetary gears 12L meshing with the internal gear 10L are provided in a casing. 1 meshes with a sun gear 14L fixed to a fixed shaft 13 erected from the center of the bottom surface 1b.

On the upper part of the lower motor unit 6L configured as described above, the middle motor unit 6M shown in FIG. The middle motor unit 6M has substantially the same configuration as the lower motor unit 6L, but the sun gear 14M is connected to the drive plate 3 and the sun so as to be located on an extension of the output shaft 4 and the fixed shaft 13. Intermediate shaft 1 supported rotatably between gears 14L
Fixed to 6. The planetary gear 12L of the lower motor unit 6L is supported via a needle bearing 19 on a connecting shaft 18 fixed to the planetary gear 12M of the middle motor unit 6M by a key 17.

Further, an upper motor unit 6U shown in FIG. 5 is laminated above the middle motor unit 6M via a thrust bearing 15. This upper motor unit
6U has substantially the same configuration as the lower and middle motor units 6L and 6M, but the sun gear 14U
The planetary gear 12U is fixed to the drive plate 3 by a key 17 and supported by a connecting shaft 20 via a needle bearing 19. A compression spring 22 as a pressing means is mounted between the pressure plate 21 mounted on the upper part of the upper motor unit 6U via the slide bearing 15 and the cover plate 2, and the elastic force of the compression spring 22 The rotors 11L, 11M, 11U of the motor units 6L, 6M, 6U are pressed against the stators 8L, 8M, 8U.

The structure for restricting the movement of each of the planetary gears 12L, 12M, 12U in the axial direction is not shown, but can be easily realized by using an appropriate thrust bearing or bearing.

Next, the driving principle of the motor units 6L, 6M, 6U will be described with respect to the lower motor unit 6L shown in FIG. As shown in the figure, a large number of piezoelectric elements 23 divided in the circumferential direction are provided on the outer periphery of the lower surface of the stator 8L fixed to the support plate 7L, and the upper and lower surfaces thereof have electrodes 24a, 24b, respectively. Are arranged. As is well known, the piezoelectric element 23 is an electrode
It has the property of expanding and contracting in the thickness and width directions when the polarity of the voltage applied to 24a and 24b is reversed, and a large number of piezoelectric elements arranged in the circumferential direction of the stator 8L made of an elastic material.
By sequentially shifting the phase of the voltage applied to 23, the stator 8L resonates and a traveling wave is formed on its surface.
Then, the rotor 11L pressed against the stator 8L by the compression spring 22 is pressed by the traveling wave in a direction opposite to the traveling direction of the traveling wave, and is driven to rotate. The above-described ultrasonic motor can be formed to be extremely thin, has a large torque at low speed rotation, and has high quietness.

Next, the operation of the embodiment of the laminated ultrasonic motor according to the present invention having the above-described configuration will be described.

As shown in FIG. 3, when the piezoelectric element 23 mounted on the stator 8L of the lower motor unit 6L is energized to drive the rotor 11L in the direction of the arrow L1, the three planetary gears 12L meshing with the rotor 11L become Sun gear 14L while rotating in the L2 direction
Revolves around in the direction of arrow L3. Then, in FIG. 4, the planet gear 12M fixed to the connecting shaft 18 supported by the planet gear 12L revolves in the direction of arrow M3. At this time, if the rotor 11M of the middle motor unit 6M is not driven, the planetary gears 12M
Rotates in the direction of arrow 2 and rotates the sun gear 14M meshing with the planetary gear 12M in the direction of arrow M4. This sun gear 14M
Rotates the sun gear 14U of the upper motor unit 6U shown in FIG. 5 in the direction of arrow U4 via the intermediate shaft 16.
At this time, if the rotor 11U of the upper motor unit 6U is not driven, the planetary gear 12U meshing with the sun gear 14U revolves in the direction of the arrow U3 while rotating in the direction of the arrow U2. Then, the revolution of the planetary gear 12U is transmitted to the drive plate 3 via the connection shaft 20, and the output shaft 4 fixed to the drive plate 3 is rotationally driven. As mentioned above, 3
The output shaft 4 is rotationally driven by the operation of only the lower motor unit 6L of the motor units 6L, 6M, 6U.

Next, when only the middle motor unit 6M is operated,
In FIG. 4, the rotor 11M is driven in the direction of arrow 1.
At this time, since the position of the connection shaft 18 is fixed by the stop of the lower motor unit 6L, the planetary gear 12M
Sun gear 14 that rotates in two directions and meshes with this planet gear 12M
Rotates in the direction of arrow 4. Then, similarly to the above, the rotation of the sun gear 14M is rotated by the intermediate shaft 16, the sun gear 14U, and the planetary gear 12
The output shaft 4 is rotationally driven via the U, the connecting shaft 20 and the driving plate 3.

Next, when only the upper motor unit 6U is operated,
In FIG. 5, the rotor 11U is driven in the direction of arrow U1.
At this time, since the sun gear 14U is fixed by stopping the lower and middle motor units 6L and 6M, the planetary gear 12U
Revolves in the direction of the arrow U3 while rotating in the direction opposite to the arrow U2, and the revolution of the planetary gear 12U drives the output shaft 4 via the connecting shaft 20 and the drive plate 3 to rotate.

As described above, when any one of the three motor units 6L, 6M, and 6U operates, the output shaft 4 is driven to rotate. However, even when a plurality of motor units 6L, 6M, and 6U are simultaneously operated, the output shaft 4 is driven. 4 can be driven to rotate.

For example, when the middle motor unit 6M is operated during the operation of the lower motor unit 6L, the planetary gear 12M in the direction of the arrow M2 in FIG. The rotation is accelerated by the driving of the rotor 11M in the direction of the arrow M1, and the planetary gear 12M and the sun gear 14M eventually rotate at twice the speed. Further, when the upper motor unit 6U is driven simultaneously,
Arrow of planetary gear 12U due to rotation of sun gear 14U in the figure
The revolving speed in the U3 direction is accelerated by driving the rotor 11U in the direction of the arrow U1, and the revolving speed is set to the lower motor unit 6L.
Is three times the revolution speed of the planetary gear 12L.

As can be understood from the above description, the output shaft 4 is driven to rotate by the operation of at least one of the three motor units 6L, 6M, 6U, and the rotation speed is controlled by the operating motor units 6L, 6M, 6U. Increases in proportion to the number of.

Next, another embodiment of the present invention will be described based on FIG. 6 and FIG. In the figure, the same members as those of the previous embodiment are denoted by the same reference numerals, and the duplicate description thereof will be omitted.

The laminated ultrasonic motor of this embodiment differs from the previous embodiment only in the configuration of the lower motor unit 6L '. That is,
This motor unit 6L 'does not include an internal gear, a planetary gear, and a sun gear, and a lower end of a connecting shaft 18' supported by a planetary gear 12M of a middle motor unit 6M via a needle bearing 19 is connected to a lower stage. Motor unit 6L 'rotor
Screwed directly to 11L '.

Therefore, according to this embodiment, instead of revolving the connection shaft 18 via the planetary gear 12L that meshes with the internal gear 10L and the sun gear 14L of the rotor 11L as in the previous embodiment,
Since the connecting shaft 18 'is fixed to the rotor 11L' and revolved directly, the structure can be simplified.

As described above, the embodiments of the laminated ultrasonic motor according to the present invention have been described in detail. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the present invention described in the appended claims. It is possible to make small design changes.

For example, the number of motor units is not limited to three, and any number of motor units can be stacked as long as the number is two or more.

Instead of transmitting power from the planetary gear of the last motor unit to the output shaft via the connection shaft and the drive plate, it is also possible to directly connect the sun gear of the last motor unit to the output shaft.

Furthermore, the number of planetary gears provided in each motor unit is not limited to three, and any number of planetary gears can be mounted. However, three or more planetary gears must be used to position the rotor with the planetary gears. Is desirable.

C. Effects of the Invention According to the above-described laminated ultrasonic motor of the present invention, a plurality of motor units each having a thin ultrasonic motor are housed in a single casing in a stacked state, and among the plurality of motor units, When at least one of the motors operates, the output shaft can be driven to rotate, so that a highly reliable fail-safe mechanism can be realized by the volume and weight of a conventional single motor. Further, by stacking the motor units, the pressing means for pressing the rotor against each stator can be shared, so that the entire motor can be formed more compact.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a laminated ultrasonic motor according to one embodiment of the present invention, FIG. 2 is an enlarged view of a part II in FIG. 1, FIG. 4 is a sectional view taken along line IV-IV of FIG. 1, FIG. 5 is a sectional view taken along line VV of FIG. 1, FIG. 6 is a longitudinal sectional view of another embodiment, and FIG. It is sectional drawing by the VII-VII line of FIG. 1 ... casing, 4 ... output shaft, 6, 6 '... motor unit, 8 ... stator, 10 ... internal gear, 11, 11' ...
... rotor, 12 ... planetary gear, 14 ... sun gear, 16 ... intermediate shaft, 18, 18 '... connecting shaft, 22 ... compression spring (pressing means), 23 ... piezoelectric element

Claims (1)

(57) [Claims] 1. A laminated ultrasonic motor in which a plurality of motor units stacked and housed in a cylindrical casing drive a common output shaft; wherein each of the motor units has a plurality of piezoelectric elements on its outer periphery. The installed stator, a rotor having an internal gear and being pressed against the stator via pressing means, a sun gear rotatably supported at the center of the casing, and meshing with the sun gear and the internal gear The planetary gears of the adjacent motor units alternately rotate relative to each other and alternately rotate the connection shaft that supports the common rotation and the intermediate shaft that integrally supports the sun gears of the adjacent motor units. Wherein the motor units are sequentially connected to each other, and a planetary gear or a sun gear of a final stage motor unit is connected to the output shaft. Ultrasonic motor.