JPH02106180A - Ultrasonic wave motor - Google Patents

Abstract

PURPOSE:To make the diameter of a rotor smaller by setting an oscillation transmitting ring on the central section of a piezoelectric elliptic motion oscillator to fix said oscillator on a bearing frame at the section of the node of oscillation, and by inserting said ring into the rotor to support the rotor rotatably on a projected section via a bearing. CONSTITUTION:When a projected shaft 13a at both ends of an ultrasonic wave motor is supported, then by the elliptic motion oscillation of the central section of an elliptic motion oscillator 12, the internal wall of a cylindrical rotor 16 is frictionally worked by an oscillation transmitting ring 15, and the cylindrical rotor 16 is rotated. The cylindrical rotor is rotatably supported by a bearing 14, and so the rotor is stably rotated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a small motor used in electronic equipment, etc.
In particular, it relates to a small ultrasonic motor with a small rotor diameter.

[Prior Art] Compared to conventional electromagnetic motors, ultrasonic motors have the following advantages: high torque can be obtained at low rotation speeds, and they have a stopping power.
It has advantages such as low electromagnetic noise, and is used for camera autofocus, automobile power motors, etc.

FIG. 7 and FIG. 8 are diagrams showing the schematic structure of a conventional ultrasonic motor, and show the surface of a metal disk 51 provided with small tooth-shaped protrusions on a ring, on which the protrusions are formed. The stator 50 has a structure in which two piezoelectric ceramic disks 52 and 53 are bonded to the back side of the stator 50, and a disk-shaped rotor 54 is pressed into contact with the stator 50. Piezoelectric ceramic discs 52 and 53
The polarization direction is opposite to the even number ':, 'J, and these two piezoelectric ceramic plates are bonded with a difference of half the dividing angle.

[Problems to be Solved by the Invention] As can be seen from FIG.
Therefore, in order to increase the driving torque, it is necessary to increase the diameters of the stator 50 and rotor 54.

Therefore, the practical minimum diameter of a conventional ultrasonic motor is 2
It was limited to 0-30mm.

Therefore, a technical object of the present invention is to provide a small-sized ultrasonic motor with a reduced rotor diameter. Furthermore,
Another technical problem of the present invention is that the diameter of Rogue is 20 m.
An object of the present invention is to provide an ultrasonic motor with a diameter of less than m.

[Means for Solving the Problems] According to the present invention, a vibration transmitting ring is provided in the center of a piezoelectric elliptical motion vibrator that can excite bending vibrations in two directions perpendicular to each other in a rod-shaped elastic body, The piezoelectric elliptical motion vibrator is fixed to a support frame at vibration nodes, and the support frame is fixed at an open end of a cup-shaped support having an open end and a protrusion on an end surface opposite to the open end. Further, the piezoelectric elliptical motion vibrator is inserted into the cylindrical rotor so that the vibration transmission ring contacts the cylindrical rotor, and the cylindrical rotor is rotatably supported by the protrusion via a bearing. An ultrasonic motor is obtained.

[Function] In the ultrasonic motor of the present invention, the piezoelectric elliptical motion oscillator is polarized by applying a DC voltage, and further, an alternating current voltage equal to the resonance frequency is applied to different parts of the piezoelectric elliptical motion oscillator. , consists of a rod-shaped elastic body that can excite bending vibrations in two directions perpendicular to each other, and when excited with an AC voltage having a phase difference so that the phases of the bending vibrations are substantially different, the rod-shaped elastic body Elliptical vibration occurs in a plane perpendicular to the direction along the central axis of the rod-shaped elastic body, with the amplitude being maximum at both ends and at the center. On the other hand, at this time, at the midpoint of the maximum parts adjacent to each other in the direction along the central axis, a vibration node is generated where the amplitude is minimum. A vibration transmission ring is provided at the center of the piezoelectric elliptic motion vibrator having such a configuration, and is fixed to a support frame at vibration nodes located symmetrically with respect to the center, and this support frame is connected to a cup-shaped support. supported and further housed within the cylindrical rotor so that the vibration transmitting ring is in contact with the inside of the cylinder, and
When a cylindrical rotor is supported via a bearing by a cup-shaped support and both ends of this cup-shaped support are fixed, the elliptical vibration in the center of the piezoelectric elliptical motion vibrator is transmitted to the cylindrical rotor that is in contact with it. and rotate it.

[Example] Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a partially cutaway perspective view showing the configuration of an ultrasonic motor according to an embodiment of the present invention. FIG. 2 is a sectional view of the ultrasonic motor of FIG. 1. In these figures, the ultrasonic motor includes a piezoelectric elliptical vibrator 12, a support frame 11, a cup-shaped support 13, a bearing 14, a vibration transmission ring 15, and a cylindrical rotor 16.

Assembly of an ultrasonic motor according to an embodiment of the present invention will be described with reference to FIGS. 3 to 6.

Fig. 3(a) shows an example of a support frame, in which both the inner and outer sides are circular, and Fig. 3(b) shows another example of the support frame, in which the inner side is circular with a part cut away. The outside is circular.

FIG. 4 shows a piezoelectric ceramic material in which electrodes are formed along the length direction of the side surface using the support frame 11 shown in FIG. 3.
, 9 is a perspective view of the case where the vibration node portion of the rod-like clear circular motion vibration is supported by the elastic body of No. 9. As shown in FIG. 4, a pair of support frames 11 and 11' is inserted through the support frames 11 and 11' to suppress the vibration of a rod-shaped piezoelectric elliptic motion vibrator 12 having a regular polygonal cross section or a circular cross section. Support the section. The inner shape of the support frames 11 and 11'' can be selected depending on the cross-sectional shape of the elliptical motion oscillator, etc. Since the shape of the support frame is symmetrical, it is difficult to resist bending vibration in directions perpendicular to each other for exciting elliptical motion. Since the influence of the support acts in the same way, it is possible to excite stable elliptic motion vibrations.

FIG. 5 is a perspective view showing (a) a cup-shaped support and (b) a bearing used in an ultrasonic motor according to an embodiment of the present invention.

FIG. 6 shows that after the vibration transmitting ring 15 is inserted into the center of the elliptical motion vibrator 12, it is attached to both ends of the elliptic motion vibrator with the support frame shown in FIG. 5(a). It is a perspective view showing a state in which a pair of cup-shaped supports 13 having a structure having a hollow portion opened at one end and a protruding shaft 13a extending outward at the other end are set. As shown in this figure, the elliptic motion vibrator 12 has a rod shape, and its vibration nodes are supported by the support frame 11. Both ends of the elliptical motion oscillator 12 are provided with a cup-shaped support 13 in the cavity thereof.
is installed with a small gap. The support frame 11 is
It is inserted through the cavity opening end 13b of the cup-shaped support 13 and fixed. It is housed in a cylindrical rotor 16, and the vibration transmission ring 15 is provided so as to lightly contact the inside of the cylindrical rotor 16, and the cylindrical rotor 16 is supported via a bearing 14 on the protruding shaft of the cup-shaped support. , an ultrasonic motor as shown in FIGS. 1 and 2 is obtained.

1 and 2, when the protruding shafts 13a at both ends of the ultrasonic motor are supported, the central part of the elliptical motion vibrator 12 vibrates in an elliptical motion, and the vibration transmission ring 15 moves against the inner wall of the cylindrical rotor 16. The cylindrical rotor 16 is rotated by rubbing. The cylindrical rotor is mounted by a bearing 14,
It rotates stably because it is rotatably supported.

[Effects of the Invention] As explained above, in the ultrasonic motor of the present invention,
The structure is simple because the shape of the vibrator for generating the driving force is simple, and the two vibration modes for generating the elliptical motion vibration including a circle are the same bending mode.

Furthermore, since a rod-shaped vibrator is used as the elliptical motion vibrator, it is easy to reduce the diameter of the cylindrical rotor, and an ultrasonic motor with a small diameter cylindrical rotor can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an ultrasonic motor according to an embodiment of the present invention, FIG. 2 is a sectional view of FIG. 1, and FIG. 3 is a support frame used in an ultrasonic motor according to an embodiment of the present invention. FIG. 4 is a perspective view showing the piezoelectric elliptical motion vibrator of the ultrasonic motor according to the present invention provided with a support frame, and FIG. 5(a) is a cup of the ultrasonic motor according to the present invention. FIG. 5(b) is a perspective view showing an example of a bearing of an ultrasonic motor according to the present invention, and FIG. 6 is a perspective view showing an example of a bearing of an ultrasonic motor according to an embodiment of the present invention. 7 and 8 are diagrams showing an ultrasonic motor according to a conventional example. In the figure, 11 and 11' are support frames, 12 is an elliptical motion oscillator,
13 is a cup-shaped support, 13a is a protruding shaft, 13b is an open end, 15 is a vibration transmission ring, and 16 is a cylindrical rotor.
51 is a metal disk, 52.53 is a piezoelectric ceramic plate, 5
4 is a rotor.

Claims (1)

[Claims] 1. A vibration transmitting ring is provided at the center of a piezoelectric elliptical motion vibrator that can excite bending vibration in two directions perpendicular to each other in a rod-shaped elastic body, and the piezoelectric elliptic motion vibrator is attached to a support frame at the vibration nodes. The support frame is fixed to the open end of a cup-shaped support having an open end and a protrusion at an end opposite to the open end, and the piezoelectric elliptical motion vibrator is fixed to the vibration transmitting ring. is inserted into the cylindrical rotor so as to be in contact with the cylindrical rotor, and the cylindrical rotor is rotatably supported by the protrusion via a bearing.