JPH06165536A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To harmonize the rigidity of a comb teeth-shaped drive part formed at a diaphram and to efficiently turn a rotor by a method wherein slits are formed in a drive part in the thickness direction of a diaphram and the width of each slit is formed to be narrower as it is advanced toward the side of a vibration part. CONSTITUTION:Slits 27 are formed in the outer circumferential face of a drive part 16 at a diaphragm 10 in the thickness direction of the drive part 16. The width of each slit 27 is made to be narrower as it is advanced toward the center of the diaphragm 10. Consequently, the base end of the drive part 16 and a vibration part 15 are set to a state that their connection part becomes large and that the drive part 16 becomes stable with reference to the vibration part 15. In addition, since the tip of the drive part 16 is formed to be thinner, the drive part 16 is easy to vibrate. As a result, the coupling force of the vibration part 15 to the drive part 16 is ensured, a rotor can be turned efficiently by traveling waves, in one direction, which are generated at the drive part 16 even if the slide contact face of the rotor urges the drive part 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic motor, and more particularly to the shape of a diaphragm which constitutes a stator.

[0002]

2. Description of the Related Art Conventionally, a driving portion having an annular shape in the thickness direction thereof is formed so as to project on the outer peripheral edge of a diaphragm constituting a stator of an ultrasonic motor. An annular rotor is placed in pressure contact with the drive unit. Further, when a voltage is applied to the piezoelectric element provided on the stator, a traveling wave is generated in the drive portion of the diaphragm, and the rotor rotates in the direction opposite to the traveling wave.

By the way, in order to increase the amplitude in the circumferential direction of the drive unit, the thickness of the drive unit may be increased. However, as the thickness of the drive unit is increased, its rigidity is increased, so that the vibration of the vibrating unit is suppressed and the amplitude of the traveling wave is reduced.

Therefore, an ultrasonic motor disclosed in Japanese Patent Laid-Open No. 3-230772 has been proposed. That is, a plurality of slits are formed at equal intervals in the radial direction of the diaphragm on one side surface of the diaphragm driving section to form a comb tooth-shaped driving section. Then,
The thickness can be provided without increasing the rigidity of the drive unit. Therefore, the amplitude in the circumferential direction can be increased without reducing the amplitude of the traveling wave, and the rotor can be efficiently rotated.

However, in the case of forming such a comb-teeth-shaped drive portion, it is necessary to form a slit for each diaphragm, which requires a long working time and a high working cost.

Therefore, in addition to this, JP-A-63-2620
An ultrasonic motor disclosed in Japanese Patent No. 69 has been proposed. In this case, the inner peripheral portion or the outer peripheral portion of the diaphragm is formed with slits having a constant width in the thickness direction of the diaphragm to form a comb-shaped drive unit, which shortens the processing time and reduces the cost. I am trying to

[0007]

However, since the rotor is placed in pressure contact with the comb-teeth-shaped drive portion, a load is applied to the drive portion. As a result, if the number of slits is increased or the slit width is increased, the thickness of the drive unit can be provided without increasing the rigidity. However, there is a problem that the coupling force with the vibrating section becomes weak and the vibration generated in the vibrating section cannot be transmitted to the driving section.

On the contrary, if the number of slits is reduced or the slit width is narrowed, the coupling force becomes stronger, but if the thickness of the driving portion is increased, the rigidity of the driving portion increases, so that the vibration of the vibrating portion is suppressed, There is a problem that the amplitude of the traveling wave is reduced.

The present invention has been made to solve the above problems, and its purpose is to harmonize the rigidity of a comb-teeth-shaped drive portion formed on a diaphragm to efficiently rotate a rotor. Another object of the present invention is to provide an ultrasonic motor that can reduce the machining time for comb teeth.

[0010]

In order to solve the above-mentioned problems, the present invention forms a drive portion projecting in the thickness direction of the vibration plate with respect to an annular vibration plate, and A piezoelectric element is arranged on the peripheral surface of the vibrating portion, which is the peripheral side or the outer peripheral side, and an annular rotor is pressed against the driving portion of the vibrating plate to apply an AC voltage to the piezoelectric element. In the ultrasonic motor that rotates the rotor by generating a traveling wave that moves in the circumferential direction in the drive unit, a slit is formed in the thickness direction of the diaphragm with respect to the drive unit, and the width of the slit is vibrated. The feature is that it becomes narrower toward the department side.

[0011]

By forming a slit in the thickness direction of the vibrating plate which becomes narrower toward the vibrating portion side, the shape of the driving portion becomes thinner from the base end to the tip end of the driving portion. Then, a large connecting portion between the vibrating portion and the driving portion is ensured, so that a decrease in coupling force between the driving portion and the vibrating portion is prevented. Further, since the tip of the drive unit is thin, the mass of the drive unit is small, and the drive unit is likely to vibrate due to the vibration of the vibrating unit. Therefore, the traveling wave in the circumferential direction generated on the support base is expanded, and the coupling force between the vibrating portion and the driving portion is secured, so that the rotor efficiently rotates by the traveling wave.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment embodying the present invention will now be described with reference to FIGS.
It will be described with reference to FIG. As shown in FIG. 1, a main body case 1 constituting an ultrasonic motor is composed of a base 2 and an upper cover 3, and the base 2 and the upper cover 3 form a storage space portion 4. A mounting portion 5 is formed on the upper surface of the center of the base 2 in a protruding manner, and an insertion hole 6 is formed in the center of the base 2. The base end of the rotary shaft 7 is inserted into the storage space 4 through the insertion hole 6.

The rotating shaft 7 is rotatably supported by a bearing 8 arranged in the insertion hole 6. Furthermore,
A cover recess 3a is formed in the upper cover 3 so as to project outward. A bearing 9 is arranged in the cover recess 3a, and the base end of the rotary shaft 7 is rotatably supported by the bearing 9. Further, an engaging portion 7a having an oval cross section and a flange 7b having a circular shape are formed on the rotary shaft 7 in the storage space 4.

An annular diaphragm 1 is provided on the upper surface of the mounting portion 5.
0 is placed, and the vibration plate 10 is pressure-bonded to the placing portion 5 with screws 11. The rotary shaft 7 is inserted into the through hole 12 of the diaphragm 10.

The vibrating plate 10 has a circular boss portion 13 through which the rotary shaft 7 is inserted, a thin connecting portion 14 formed on the outer periphery of the boss portion 13, and an outer periphery of the connecting portion 14. The vibrating section 15 and the driving section 16 formed on the outer circumference of the vibrating section 15.

Power supply lines 17a and 17b are introduced into the storage space 4 of the main body case 1. Then, one power supply line 17a is led out to the upper surface side of the diaphragm 10 through a through hole 13a formed in the boss portion 13 of the diaphragm 10. Piezoelectric elements 18a, 18b, such as a pair of annular PZTs, are attached to the upper and lower surfaces of the vibrating portion 15 with an adhesive or the like. A flexible printed circuit (hereinafter, simply referred to as F) is provided on the piezoelectric elements 18a and 18b.
19a and 19b (referred to as PC) are attached. The power supply line 17a is connected to the FPC 19a,
The power supply line 17b is connected to the PC 19b. The vibrating plate 10 and the pair of piezoelectric elements 18a and 18b constitute a stator.

High-frequency voltages having a phase difference of 90 deg are applied to the piezoelectric elements 18a and 18b by the power supply lines 17a and 17b, respectively, and electric energy is converted into vibration energy. Therefore, the pair of piezoelectric elements 18a and 18b perform expansion / contraction operation (vibration), and due to this expansion / contraction operation, a traveling wave traveling in the circumferential direction is generated in the drive unit 16.

A rotor 20 made of aluminum or the like is mounted on the upper surface of the vibration plate 10. A sliding contact portion 21 protruding in the thickness direction of the rotor 20 is formed on the outer peripheral edge of the rotor 20, and a lining material (wear-resistant Teflon resin) 22 is provided on the lower surface of the sliding contact portion 21. ing. The sliding contact portion 21 on which the lining material 22 is formed comes into contact with the drive portion 16 of the diaphragm 10.

An insertion hole 23 having a flat oval shape is provided at the center of the rotor 20. And this insertion hole 2
The engaging portion 7 a of the rotary shaft 7 is inserted into the shaft 3. Therefore, the rotor 20 and the rotating shaft 7 are in a state of being integrally rotatable. The rotor 20 can move in the axial direction of the rotary shaft 7.

A flange 7 is provided on the engaging portion 7a of the rotary shaft 7.
The pressurizing plate 24 that comes into contact with b is inserted, and rotates integrally with the rotary shaft 7 and the rotor 20.
Then, it can move in the axial direction of the rotary shaft 7. A leaf spring 25 is in contact with the pressure plate 24. The leaf spring 25 and the rotor 20
An anti-vibration rubber 26 is provided between the and.

The pressure plate 24 presses the rotor 20 downward via the leaf spring 25 and the vibration-proof rubber 26. Therefore, the driving unit 16 of the diaphragm 10
The sliding contact surface 21 of the rotor 20 is pressed against the upper surface of the. The pressure contact force can be adjusted by changing the thickness of the spacer 27 inserted into the rotary shaft 7 between the flange 7b and the bearing 9.

Therefore, the FPC is connected to the feeder lines 17a and 17b.
When a high frequency voltage having a phase difference of 90 deg is applied to each of the piezoelectric elements 18a and 18b via 19a and 19b, the piezoelectric elements 18a and 18b vibrate and a unidirectional traveling wave is generated in the drive unit 16 of the diaphragm 10. To do. The rotor 20 rotates in a direction opposite to the traveling direction of this traveling wave.

As shown in FIGS. 2 and 3, the vibration plate 10 is
A slit 27 is formed on the outer peripheral surface of the drive unit 16 in the direction of the thickness of the drive unit 16. The width of the slit 27 becomes narrower toward the center of the diaphragm 10. In this embodiment, the slit 27 has a trapezoidal plane shape. Therefore, the driving unit 16 is formed in a trapezoidal shape in plan view. In other words, the base portion of the drive unit 16 has a long bottom side and a top end side has a short top trapezoidal shape. Therefore, the base end of the driving unit 16 and the vibrating unit 15 enlarge the connecting portion so that the driving unit 16 is stable with respect to the vibrating unit 15.

Now, the power supply line 17 from the drive circuit (not shown)
Piezoelectric element 1 via a, 17b and FPC 19a, 19b
A high frequency voltage having a phase difference of 90 deg is applied to 8a and 18b. Then, the piezoelectric elements 18a and 18b expand and contract (vibrate) to generate a unidirectional traveling wave in the drive unit 16.
The traveling wave causes the rotor 20 to rotate in the direction opposite to the traveling direction of the traveling wave, and the rotation causes the rotating shaft 7 to rotate.

Further, since the slit 27 is formed on the outer peripheral surface of the drive unit 16 so as to become narrower toward the diaphragm 10, the drive unit 16 has a flat base trapezoidal shape having a long base on the base end side and a short top side. It is formed.

Therefore, since the connecting portion of the driving portion 16 can be enlarged with respect to the vibrating portion 15, the driving portion 16 becomes stable with respect to the vibrating portion 15. That is, even if a plurality of slits 27 are formed in the driving unit 16, it is possible to prevent the coupling force between the vibrating unit 15 and the driving unit 16 from decreasing.
Further, since the leading end of the drive unit 16 is formed to be thinner, the drive unit 16 is likely to vibrate.

As a result, since the coupling force between the vibrating portion 15 and the driving portion 16 is secured, even if the sliding contact surface 21 of the rotor 20 presses the driving portion 16, the rotor 20 is generated in the driving portion 16. It can be rotated by a traveling wave in one direction.

Further, even if a plurality of slits 27 are formed for the drive unit 16, the coupling force between the vibration unit 15 and the drive unit 16 does not decrease. Therefore, the weight of the drive unit 16 can be reduced, and the drive unit 16 can be made thick. As a result, the amplitude in the circumferential direction can be increased without reducing the amplitude of the traveling wave generated in the drive unit 16, and the rotor 20 can be efficiently rotated.

Further, since the slits 27 are formed in the thickness direction of the vibrating plate 10, the slits 27 may be formed along the outer peripheral surface of the driving unit 16 in a state where the vibrating plates 10 are stacked. it can. As a result, since the slits 27 are formed in the plurality of diaphragms 10 at once, the processing time can be shortened and the cost increase can be suppressed.

In the present embodiment, the drive portion 16 is provided on the outer peripheral edge of the diaphragm 10. However, as shown in FIGS. 4 and 5, the drive portion 16 is provided on the inner peripheral surface of the through hole 12 in the drive portion 16.
It is also possible to form. The diaphragm 10 shown in FIGS. 4 and 5 is used for an ultrasonic motor as shown in FIG. It should be noted that the members having the same functions and the same components as those in the above-described embodiment are designated by the same reference numerals and the description thereof will be omitted.

In this case, although the slit 27 is formed in the driving portion 16, the slit 27 has a trapezoidal shape whose width becomes narrower toward the vibrating portion 15. Therefore, the base of the drive unit 16 on the side of the vibration unit 15 becomes longer, and the drive unit 16
It may have a trapezoidal shape in which the upper side on the tip side of the is shortened.

Further, in the present embodiment, the shape of the drive unit 16 is a trapezoidal plane, but as shown in FIG. 6, the shape of the drive unit 16 is a plane triangle, or as shown in FIG. It is also possible that the shape of the drive unit 16 is a plane arc shape. In addition, in this another example, the shape of the slit 27 is a flat triangular shape or a flat trapezoidal shape, but other shapes can be used as long as the shape becomes narrower toward the diaphragm 15 side.

[0033]

As described in detail above, according to the present invention, the rigidity of the comb-teeth-shaped drive portion formed on the diaphragm is harmonized.
There is an excellent effect that the rotor can be efficiently rotated and the processing time of the comb teeth can be shortened.

[Brief description of drawings]

FIG. 1 is a sectional view of an ultrasonic motor according to the present invention.

FIG. 2 is a perspective view of a diaphragm.

FIG. 3 is a plan view of a diaphragm.

FIG. 4 is a perspective view showing another example of the diaphragm.

FIG. 5 is a plan view showing another example of the diaphragm.

FIG. 6 is a plan view showing another example of the diaphragm.

FIG. 7 is a plan view showing another example of the diaphragm.

FIG. 8 is a cross-sectional view of an ultrasonic motor configured using a diaphragm of another example.

[Explanation of symbols]

10 ... Vibration plate, 15 ... Vibration part, 16 ... Drive part, 18a,
18b ... Piezoelectric element, 20 ... Rotor, 27 ... Slit

Front page continued (72) Inventor Noboru Handa No. 390 Umeda, Kosai City, Shizuoka Asmo Co., Ltd. In-house (72) Inventor Yasuaki Kawai One of 41, Yokomichi, Nagakute-cho, Aichi-gun, Aichi-gun Toyota Central Research Institute Co., Ltd.

Claims (1)

[Claims] 1. A drive part projecting in a thickness direction of the vibration plate is formed with respect to an annular vibration plate, and the vibration part is provided on an inner peripheral side or an outer peripheral side of the drive part. A piezoelectric element is provided, and an annular rotor is pressed against the drive portion of the diaphragm, and an alternating voltage is applied to the piezoelectric element to generate a traveling wave that moves in the circumferential direction in the drive portion. In the ultrasonic motor for rotating the rotor, a slit is formed in the thickness direction of the diaphragm with respect to the drive unit, and the width of the slit is made narrower toward the vibration unit side. Ultrasonic motor.