JP3120228B2 - Ultrasonic motor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the shape of a vibrator of an ultrasonic motor. 2. Description of the Related Art In a conventional ultrasonic motor which has been conventionally considered, as shown in FIGS. 3 and 4, a vibrating body 4 having a piezoelectric element 5 bonded thereto has two different phases. When the high frequency voltage is applied, a traveling wave is generated in the vibrating body, and the friction material 3 adhered to the moving body 2 and the surface forming the comb teeth 4a of the vibrating body 4 in contact with the friction material 3 are pressed against each other. Driven. [0003] In the structure of the ultrasonic motor as described above, the comb teeth of the vibrating body and the friction material adhered to the moving body are pressed against each other and rotated. The softer friction material was shaved off. If the maximum displacement position of the vibrating body varies from one position to another, and if the comb teeth are displaced from the maximum displacement position in the radial direction, the friction material is scraped by the manner of contact between the comb teeth and the friction material. It was different. Also, if left unattended, the vibrating body sinks into the friction material, so that the static torque increases and the self-starting property deteriorates. SUMMARY OF THE INVENTION It is an object of the present invention to provide an ultrasonic motor having a vibrating body with less wear of a friction material, excellent durability and good self-startability. SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a vibrating body having a plurality of concentric teeth on a part thereof in a radial direction. A configuration is provided in which a chamfered portion is provided on the ridgeline on the peripheral side and the ridgeline on the outer peripheral side.
In addition, a configuration is provided in which the chamfered portions are provided on all the ridge lines at the tips of the plurality of comb teeth of the vibrating body. [0006] According to the above configuration, the friction material is less likely to be scraped, so that wear powder generated by scraping the friction material is reduced. Further, since the friction material is less entangled even when left standing, a vibrating body having excellent durability and good self-starting properties can be obtained. Embodiments of the present invention will be described below with reference to the drawings. 3 and 4 show general ultrasonic motors. Moving body 2 with friction material 3 bonded
Has a central axis 1 and is rotatable via a bearing 6 to a vibrating body 4 to which a piezoelectric element 5 is bonded. The moving body 2 that is in pressure contact with the vibrating body 4 is moved by the bending vibration wave component generated by applying two high-frequency voltages having different phase differences to the piezoelectric element 5 bonded to the vibrating body 4. It is driven by friction by the comb teeth 4a to rotate. Here, the comb tooth 4a is a so-called displacement enlarging mechanism for enlarging a minute bending vibration wave component generated on the surface of the vibrating body 4. FIGS. 1 and 2 show a first embodiment of the ultrasonic motor vibrator according to the present invention. The friction material 3 and the vibrator 4 shown in FIG. Are chamfered 4b, 4b 'on both sides of the comb tooth 4a in the circumferential direction of the comb tooth portion 4a, which is the portion where the contact is made. By applying the chamfers 4b and 4b 'to both sides in this way, the self-starting property is good even when driving, and the friction material 3 shown in FIG.
It is possible to realize an ultrasonic motor with less scraping and excellent durability. FIGS. 5 (a), 5 (b), 5 (c), and 5 (d) are views showing the behavior of the comb teeth according to the variation of the comb set position according to the present invention. Here, FIG. 5A is a diagram showing the behavior in the vertical direction in the radial direction of the vibrating body, FIG. 5B is a diagram showing the case where the comb tooth set position is set on the maximum displacement position, and FIG.
FIG. 5C is a diagram illustrating a case where the comb tooth set position is shifted outward from the maximum displacement position, and FIG. 5D is a diagram illustrating a case where the comb tooth set position is shifted inward from the maximum displacement position. When the maximum displacement position of the vibrating body 4 varies, and as shown in FIGS. 5 (c) and 5 (d), the comb teeth 4a are displaced from the maximum displacement position in the radial direction. 5 (c ') and FIG.
In order to exhibit the behavior as shown in FIG.
The method of shaving the friction material 3 shown in FIG. 4 differs depending on the manner of contact of the friction material 3 shown in FIG.
Also, if left unattended, the comb teeth 4a would sink into the friction material 3 shown in FIG. 4 and the self-starting property would deteriorate. Therefore, as in the embodiment shown in FIGS. 6 and 7, the comb member 4a, which is the portion where the friction member 3 and the vibrating body 4 are in contact with each other as shown in FIG. The above problem is solved by chamfering 4c, 4c 'on the inner and outer circumferences of the teeth 4a. FIGS. 8 and 9 show a third embodiment according to the present invention, and the chamfers 4b, shown in FIGS. 1 and 2 and FIGS.
FIG. 4 is a diagram showing a case where both of the embodiments 4b ′, 4c, and 4c ′ are used. The same effect can also be obtained by cutting the corners of the comb teeth 4a to be chamfered as shown in FIGS. 1 and 2 and FIGS. 6 and 7 instead of chamfering them. In the embodiment described above, the ultrasonic motor
The vibrating body 4 has a surface in contact with the friction material 3 and a comb tooth 4
By chamfering the ridgeline formed by the vertical surface forming a, the friction material 3 is less likely to be shaved, and the amount of abrasion powder is reduced. Further, even if the vibrating body 4 is sunk into the friction material 3, the vibrating body has good self-starting property because it is chamfered and has no corners. According to the present invention, there is provided an ultrasonic motor, comprising: a vibrating body having a plurality of comb teeth which are concentric in a part in the radial direction; A chamfer is provided on the ridgeline on the outer peripheral side. In addition, since the chamfers are provided on all the ridges of the tips of the plurality of comb teeth of the vibrating body, the friction material is less scraped and has excellent durability.
Further, even when the apparatus is left standing still, there is an effect that an ultrasonic motor having a vibrator having good self-starting properties can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view showing a first embodiment of a vibrator of an ultrasonic motor according to the present invention. FIG. 2 is a sectional view of the first embodiment. FIG. 3 is a plan view of a vibrating body of a conventional general ultrasonic motor. FIG. 4 is a cross-sectional view of a conventional general ultrasonic motor. FIG. 5 is an explanatory diagram showing a behavior of a comb tooth portion according to a change in a comb tooth set position according to the present invention. FIG. 6 is a plan view showing a second embodiment of the vibration body of the ultrasonic motor according to the present invention. FIG. 7 is a sectional view of the second embodiment. FIG. 8 is a plan view showing a third embodiment of the vibration body of the ultrasonic motor according to the present invention. FIG. 9 is a sectional view of the third embodiment. [Description of Signs] 1 Central axis 2 Moving body 3 Friction material 4 Vibrating body 4a Comb 5 Piezoelectric element 6 Bearing or more

Claims (1)

(57) [Claims] In an ultrasonic motor having a vibrating body that generates a vibration wave and a moving body that is frictionally driven by the vibrating body, the vibrating body includes a plurality of concentric comb teeth in a part in a radial direction. An inner diameter of a surface that contacts the comb teeth is smaller than an inner diameter of the comb teeth, and an outer diameter of a surface of the moving body that contacts the comb teeth is larger than an outer diameter of the comb teeth, and An ultrasonic motor characterized in that chamfers are provided on all ridges of the contact surface of the comb teeth with the moving body.