JPH04347585A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To provide a circular type ultrasonic motor in which problems of generation of noise due to difficulty in uniform contact of a vibrator with a moving element, a decrease in the efficiency of a motor are eliminated, and which is light in weight, excellent in low speed stability and simple in manufacturing process in the motor for generating driving force by exciting an elastic wave by using a piezoelectric element such as piezoelectric ceramic. CONSTITUTION:A moving element 7 is formed of a moving element beam 8, a moving element first protrusion 9 extended from one end of the beam 8, and a moving element second protrusion 10 extended from the other end of the beam 8. A vibrator 11 is pressurized through a surface A of the protrusion 10, and the protrusion 11 is brought into contact with the vibrator 11. The element 7 is formed in a beam structure of cantilevered condition to absorb waviness of the contact surface of the vibrator 11 with the element 7. Further, the protrusion 10 is brought into contact with the vibrator 11 at an inner peripheral side from the center of the vibrator 11.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic motor that generates driving force by exciting elastic waves using a piezoelectric material such as a piezoelectric ceramic, and more particularly to the structure of a moving body of an ultrasonic motor.

0002

2. Description of the Related Art In recent years, ultrasonic motors have attracted attention, in which elastic vibrations are excited in a vibrating body made of a piezoelectric material, and the vibrations are used as driving force.

[0003] The conventional technology of ultrasonic motors will be explained below with reference to the drawings. FIG. 7 is a partially cutaway perspective view of a conventional annular ultrasonic motor. In the same figure,
Reference numeral 1 denotes an annular vibrating body constructed by bonding an annular piezoelectric body 3 to the bottom surface of an annular elastic substrate 2 having a plurality of protrusions 1a. Further, reference numeral 4 denotes a movable body consisting of an annular elastic body 5 coupled with a wear-resistant friction material 6, and is installed in pressure contact with the vibrating body 1.

In the above ultrasonic motor, metals such as steel and stainless steel have conventionally been used as the material for the elastic body 5, and a wear-resistant friction material 6 is attached to the elastic body 5 by a method such as bonding. By combining them, a moving body 4 of an ultrasonic motor is constructed.

The piezoelectric body 3 has two sets of drive electrodes, and when two AC voltages having a predetermined phase difference are applied to the drive electrodes, the piezoelectric body 3 undergoes stretching and contraction vibration, and the elastic substrate 2 Since it acts to resist expansion and contraction, a traveling wave of bending vibration is excited in the vibrating body 1 due to the same effect as that of a bimetal. Any point on the surface of the vibrating body 1 moves in an elliptical locus due to the traveling wave of bending vibration. Projection 1a
is the horizontal direction of this elliptical trajectory (component in the direction in which the traveling wave travels)
Expand the displacement of. The movable body 4 installed in pressure contact with the protrusion 1a of the vibrating body 1 is rotated by being driven by frictional force due to the enlarged lateral displacement.

[0006]

[Problems to be Solved by the Invention] As described above, the ultrasonic motor excites a traveling wave of bending vibration with an amplitude of several microns in the vibrating body 1 consisting of the piezoelectric body 3 and the elastic substrate 2, and This motor magnifies the lateral displacement with the protrusion 1a and drives the movable body 4 installed in pressure contact with the tip of the protrusion 1a.

Therefore, when the movable body 4 is constructed by bonding the wear-resistant friction material 6 to the elastic body 5 made of metal or the like as described above, the traveling wave of the bending vibration caused by the vibrating body 1 can be efficiently moved. In order to transmit the wave to the body 4, the friction material 6 needs to have enough rigidity to prevent the friction material 6 from being significantly elastically deformed in the lateral direction (the direction of travel of the traveling wave) due to the load torque of the ultrasonic motor.

[0008] Furthermore, in order for the vibrating body 1 and the movable body 4 to be in surface contact with each other in a pressurized state and to efficiently transmit the traveling wave of the bending vibration from the vibrating body 1 to the movable body 4, it is necessary to It is necessary to achieve uniform contact, but if a highly rigid material such as metal or ceramic is used for the contact surface, the elastic deformation in the vertical direction when pressure is applied becomes small, making it difficult to achieve uniform contact. Therefore, there is a problem in that the motor efficiency is reduced along with the generation of noise.

On the other hand, even when the movable body 4 is constructed by bonding the wear-resistant friction material 6 to the elastic body 5 made of metal or the like as described above, when the thickness of the friction material 6 is reduced, Although this differs depending on the pressing force of the motor, there are cases where noise is generated and the motor efficiency is reduced. This is because by reducing the thickness of the friction material 6, the vertical elastic deformation of the movable body 4 becomes smaller, making it impossible to achieve uniform contact and reducing the damping against unnecessary vibrations. , which poses a major problem in practice.

The present invention has been made to solve these conventional problems, and aims to provide an ultrasonic motor that realizes uniform contact between a vibrating body and a moving body and has high output transmission efficiency. , it is also possible to simplify the manufacturing process by reducing the number of parts of the moving body and omitting the bonding process.

[0011]

[Means for Solving the Problems] In order to achieve this object, the ultrasonic motor of the present invention includes a moving body beam portion and a moving body portion extending from one end of the moving body beam portion. The movable body second protrusion extends from the other end of the movable body beam. Further, the movable body is configured to be pressurized with the vibrating body through the first protrusion, and to be brought into contact with the vibrating body through the second movable body protrusion.

0012

[Operation] Therefore, according to the present invention, a movable body includes a movable body beam, a movable body first protrusion extending from one end of the movable body beam, and the other end of the movable body beam. By applying pressure to the vibrating body through the movable body first protrusion and bringing the movable body second protrusion into contact with the vibrating body, one end support condition can be achieved. The beam structure has the effect of absorbing the waviness of the contact surface between the vibrating body and the moving body (surface correction effect), ensuring stable and uniform contact, thereby reducing the bending vibration caused by the vibrating body. It becomes possible to efficiently transmit traveling waves to a moving body.

Furthermore, in addition to the above-mentioned effect, by bringing the second protrusion of the moving body into contact with the vibrating body on the inner circumferential side of the center of the vibrating body, the variation in the amplitude of the vibrating body is smaller on the inner circumferential side. Since it has good stability against load fluctuations, it is possible to realize an ultrasonic motor with excellent low-speed stability.

Furthermore, by constructing the movable body from a carbon fiber-reinforced resin composite reinforced with at least carbon fiber, this composite has excellent wear resistance, and at the same time, by using carbon fiber, it is possible to reduce frictional contact. Since it has the effect of imparting appropriate lubricity to the surface, it is possible to maintain stable motor characteristics even during long-term operation, making it possible to realize an ultrasonic motor with excellent long-term reliability.

Furthermore, by constructing the movable body from a carbon fiber-reinforced resin composite reinforced using at least carbon fibers, compared to a configuration in which the friction material is bonded to a metal elastic body,
It is possible to reduce the number of parts of the moving body and simplify the manufacturing process by omitting the bonding process, and at the same time, it is possible to reduce the weight of the moving body, thereby realizing a lightweight ultrasonic motor. Can be done.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram of the main parts of an ultrasonic motor according to an embodiment of the present invention. In the figure, reference numeral 7 indicates a moving body beam 8, a moving body first protrusion 9 extending from one end of the moving body beam 8, and a moving body first protrusion 9 extending from the other end of the moving body beam 8. The moving body is constituted by a second moving body protrusion 10. Reference numeral 11 denotes a vibrating body in which a piezoelectric body 13 is coupled to an elastic substrate 12 having a rectangular protrusion 12a. Furthermore, an ultrasonic motor is constructed by applying pressure to the vibrating body 11 with the A side of the first protrusion 9 of the movable body and bringing it into contact with the vibrating body 11 with the second protrusion 10 of the movable body.

In the above embodiment, the lateral displacement caused by the traveling wave of the bending vibration excited by the vibrating body 11 is magnified by the plurality of projections 12a to drive the movable body 7 installed in pressurized contact. . Therefore, in order to efficiently transmit the traveling wave of the bending vibration caused by the vibrating body 11 to the movable body 7, the effect (surface correction effect) for absorbing the waviness of the contact surface between the vibrating body 11 and the movable body 7 must be moved. It is placed on the body 7 to make the moving body 7 follow the vibrating body 11, and at the same time, it has enough rigidity to prevent the contact surface of the moving body 7 from being significantly elastically deformed in the lateral direction (the direction of travel of the traveling wave) due to the load torque. There is a need.

In the present invention, paying attention to the above points, the movable body 7 has a beam structure with one end supported, so that the movable body beam portion 8 can reduce the waviness of the contact surface between the vibrating body 11 and the movable body 7. It becomes possible to provide an effect for absorption (surface correction effect).

Furthermore, the moving body 7 is made of a carbon fiber-reinforced resin composite in order to increase the rigidity by using carbon fiber and at the same time compensate for the insufficient mechanical strength with a resin alone. Here, the reason for using carbon fiber is that by using carbon fiber, the effect of improving the rigidity of the moving body 7 is greater with the same fiber content compared to inorganic fibers such as glass fiber, and therefore, it is possible to use carbon fiber with less fiber content. This is because it is possible to increase the rigidity of the friction contact surface by increasing the amount, and at the same time, it is possible to improve the mechanical strength of the moving body 7.

Furthermore, since the required rigidity of the moving body 7 varies depending on the pressing force of the ultrasonic motor, it depends on the content of carbon fiber contained in the carbon fiber reinforced resin composite or the width and thickness of the moving body beam portion 8. By adjusting, the rigidity of the moving body 7 can be adjusted.

Next, the present invention will be explained in more detail with reference to specific examples. (Embodiment 1) FIGS. 2(a) and 2(b) show the main components of an annular ultrasonic motor according to a first embodiment of the present invention. As shown in the figure, a plurality of rectangular By adhering the toroidal piezoelectric body 15 to the bottom surface of the toroidal elastic substrate 14 made of stainless steel having the shaped protrusion 14a, the toroidal vibrating body 16
was constructed. Next, 30% by weight carbon fiber and 70% by weight
By injection molding the kneaded product with polyphenylene sulfide resin, an annular moving body 17 made of a carbon fiber reinforced resin composite having an annular shape and a specific gravity of 1.45 was obtained. Further, the annular moving body 17 was installed in pressure contact with the annular vibrating body 16 using a disc spring (not shown), thereby constructing the annular ultrasonic motor of the first embodiment.

As shown in the cross section of FIG. 2(b), this annular moving body 17 has a toric moving body beam portion having a width of 3w/8, where w is the width of the bottom surface of the annular vibrating body 16. 18, an annular moving body first protrusion 19 having a width of 3w/8 extending from the outer periphery of the annular moving body beam 18, and w/ extending from the inner periphery of the annular moving body beam 18. The annular movable body second protrusion 20 has a width of 4, and is brought into contact with the annular vibrating body 16 with a width of w/4.

Note that the width of the annular moving body beam portion 18 is not limited to the above-mentioned dimensions, and the optimum width of the annular moving body beam portion 18 and the optimum thickness of the toric moving body beam portion 18 (t1 in the drawing) ) and the optimum height of the second protrusion 20 of the annular moving body (
t2) in the drawings varies depending on the pressing force of the ultrasonic motor, so by adjusting the width or thickness of the annular moving body beam portion 18 and the height of the toric moving body second protrusion 20, the annular moving body can be adjusted. 17 rigidity can be adjusted.

(Embodiment 2) FIGS. 3(a) and 3(b) show the main components of an annular ultrasonic motor according to a second embodiment of the present invention. In the following embodiments, the same parts as in the first embodiment will be described with the same reference numerals. As shown in the figure, an annular vibrating body 16 was constructed by bonding an annular piezoelectric body 15 to the bottom surface of a stainless steel annular elastic substrate 14 having a plurality of rectangular protrusions 14a. Next, by injection molding a mixture of 30% by weight of carbon fiber and 70% by weight of polyetheretherketone resin, a circle made of a carbon fiber reinforced resin composite having an annular shape and a specific gravity of 1.44 is produced. An annular moving body 21 was obtained. Further, the annular moving body 21 was installed in pressurized contact with the annular vibrating body 16 using a disc spring (not shown), thereby constructing the annular ultrasonic motor of the second embodiment.

As shown in the cross section of FIG. 3(b), this annular moving body 21 has a toric moving body beam portion having a width of w/4, where w is the width of the bottom surface of the annular vibrating body 16. 22 and
An annular moving body first protrusion 23 extending from the inner periphery of the annular moving body beam 22 and having a width of w/4 and a width of w/4 extending from the outer periphery of the annular moving body beam 22. The second protrusion 24 of the annular moving body has a width, and is brought into contact with the annular vibrating body 16 with a width of w/4.

(Embodiment 3) FIGS. 4(a) and 4(b) show the main components of an annular ultrasonic motor according to a third embodiment of the present invention. Rectangular protrusion 1
An annular vibrating body 16 was constructed by adhering an annular piezoelectric body 15 to the bottom surface of an annular elastic substrate 14 made of stainless steel having a diameter of 4a. Next, 30% by weight of carbon fiber and 7
By injection molding a kneaded product with 0% by weight of polyethersulfone resin, an annular moving body 25 made of a carbon fiber reinforced resin composite having an annular shape and a specific gravity of 1.47 was obtained. Further, the annular moving body 22 is connected to the annular vibrating body 16.
The annular ultrasonic motor of the third embodiment was constructed by installing the motor in pressure contact using a disc spring (not shown).

As shown in the cross section of FIG. 4(b), this annular moving body 25 has a toric moving body beam portion having a width of w/4, where w is the width of the bottom surface of the annular vibrating body 16. 26 and
An annular moving body first protrusion 27 having a width of 3w/8 extending from the outer periphery of the annular moving body beam 26 and a width of w/3 extending from the inner periphery of the annular moving body beam 26 A taper 27 is provided on the side of the annular moving body beam portion 26 facing the annular vibrating body 16, and the annular moving body second protrusion 28 has a width of w/3. It is in contact with the body 16.

As described above, by providing the taper 27 on the annular moving body beam 26, the second protrusion 29 of the annular moving body
It is possible to increase the rigidity of the contact portion and at the same time increase the surface correction effect.

(Embodiment 4) FIGS. 5(a) and 5(b) show the main components of an annular ultrasonic motor according to a fourth embodiment of the present invention. An annular vibrating body 16 was constructed by bonding an annular piezoelectric body 15 to the bottom surface of a stainless steel annular elastic substrate 14 having a rectangular protrusion 14a. Next, by injection molding a mixture of 30% by weight of carbon fiber and 70% by weight of polyphenylene sulfide resin, a ring-shaped product with a specific gravity of 1.4
An annular moving body 30 made of a carbon fiber reinforced resin composite material No. 5 was obtained. Further, the annular moving body 30 was installed in pressure contact with the annular vibrating body 16 using a disc spring (not shown), thereby constructing the annular ultrasonic motor of the fourth embodiment.

As shown in the cross section of FIG. 5(b), this annular moving body 30 has a toric moving body beam portion having a width of 3w/8, where w is the width of the bottom surface of the annular vibrating body 16. 31, and 3w/3w extending from the outer periphery of the annular moving body beam portion 31.
The annular moving body first protrusion 32 has a width of 8, and the annular moving body second protrusion 33 extends from the inner circumference of the annular moving body beam 31 and has a width of w/6. , the annular moving body second protrusion 33 is brought into contact with the annular vibrating body 16 on the inner circumferential side of the center.

Note that the width of the annular moving body beam 31 is not limited to the above-mentioned dimensions, and the optimum width of the annular moving body beam 31 and the optimum thickness of the annular moving body beam 31 (t1 in the drawing) ) and the optimum height of the second protrusion 33 of the annular moving body (
t2) in the drawings varies depending on the pressing force of the ultrasonic motor, so by adjusting the width or thickness of the annular moving body beam portion 31 and the height of the toric moving body second protrusion 33, the annular moving body can be adjusted. 30 stiffness can be adjusted.

As described above, by bringing the annular moving body 30 into contact with the annular vibrating body 16 on the inner circumference side of the center,
The variation in the amplitude of the annular vibrating body 16 is smaller on the inner circumference side, and the stability against external load fluctuations is better.
An ultrasonic motor with excellent low-speed stability can be realized.

(Embodiment 5) FIGS. 6(a) and 6(b) show the main components of an annular ultrasonic motor according to a fifth embodiment of the present invention. An annular vibrating body 16 was constructed by bonding an annular piezoelectric body 15 to the bottom surface of a stainless steel annular elastic substrate 14 having a rectangular protrusion 14a. Next, by injection molding a mixture of 30% by weight of carbon fiber and 70% by weight of polyethersulfone resin, a ring made of a carbon fiber reinforced resin composite having an annular shape and a specific gravity of 1.47 is produced. An annular moving body 34 was obtained. Furthermore, this annular moving body 34 is connected to the annular vibrating body 1.
The annular ultrasonic motor of the fifth embodiment was constructed by installing the motor 6 in pressure contact using a disc spring (not shown).

As shown in the cross section of FIG. 6(b), this annular moving body 34 has a toric moving body beam portion having a width of w/4, where w is the width of the bottom surface of the annular vibrating body 16. 35 and
An annular moving body first protrusion 36 having a width of w/4 extending from the inner periphery of the annular moving body beam 35 and a width of w/8 extending from the outer periphery of the annular moving body beam 35. The second protrusion 37 of the annular moving body has a width, and the second protrusion 37 of the annular moving body is brought into contact with the annular vibrating body 16 on the inner circumferential side from the center.

As shown in the above five embodiments, by constructing the movable body from a carbon fiber-reinforced resin composite reinforced with at least carbon fiber, it is possible to reduce friction like a conventional annular ultrasonic motor. There is no need for an adhesion process for bonding the material to the metal elastic body, and it can be easily molded using a mold by a method such as injection molding or compression molding. Furthermore, with the above configuration, the weight of the moving body is lower than that of a moving body of the same size that is constructed by combining a friction material with a stainless steel elastic body like a conventional annular ultrasonic motor. It is possible to reduce the

Specific examples have been described above, and in the five specific examples above, the content of carbon fibers contained in the carbon fiber reinforced resin composite that constitutes the moving body is determined by the pressing force of the ultrasonic motor. However, if the fiber content is less than 5% by weight, the effect of improving rigidity will be insufficient and the abrasion resistance of the friction contact surface of the moving body will be insufficient. When the fiber content exceeds 50% by weight, it depends on the molding method or the fluidity of the resin, but
Since molding becomes difficult and the mechanical strength of the molded product becomes brittle, it is necessary to keep the amount in the range of 5% by weight or more and 50% by weight or less. Judging comprehensively from the material properties required for the moving body, the formability of the moving body, the cost of the moving body, etc., 15
It is desirable that the amount is from 35% by weight to 35% by weight.

Further, in the same example, carbon fiber was used as the type of reinforcing fiber, but it is also possible to use a combination of inorganic fiber other than carbon fiber with the above-mentioned carbon fiber. In order to adjust the lubricity, it is also possible to combine the fibers with an inorganic filler such as graphite powder, tetrafluoroethylene powder, molybdenum sulfide powder, or graphite fluoride powder.

Furthermore, in the above five specific examples, thermoplastic resins such as polyphenylene sulfide resin, polyether ether ketone resin, and polyether sulfone resin were used as the resin constituting the carbon fiber reinforced resin composite. , but not limited to these. As a guideline when selecting a resin constituting this carbon fiber reinforced resin composite, it is desirable to use a resin with heat resistance of 150°C or higher and a high heat distortion temperature.The reason for this is that the heat resistance of the resin is 150°C or less, and if a resin with a low heat distortion temperature is used, wear of the friction contact part of the moving body will be accelerated, causing deterioration of motor performance, making it difficult to ensure long-term reliability. Become. From the above point of view, in addition to the resins shown in the examples, thermoplastic resins such as polysulfone resins, polyarylate resins, polyamideimide resins, polyetherimide resins, polyimide resins, wholly aromatic polyester resins, phenolic resins, bismaleimide triazine, etc. It is also possible to use thermosetting resins such as resins and polyimide resins.

[0040]

[Effects of the Invention] As is clear from the above embodiments, the ultrasonic motor of the present invention has a beam structure in which the moving body is supported at one end, thereby realizing an ultrasonic motor with high output transmission efficiency, and at the same time It is possible to simplify the manufacturing process by reducing the number of body parts and omitting the bonding process. Moreover, by bringing this moving body into contact with the vibrating body at the inner peripheral side of the vibrating body, an ultrasonic motor with excellent low-speed stability can be realized. Furthermore, by constructing this moving body from a carbon fiber-reinforced resin composite reinforced with at least carbon fiber, it is possible to realize an ultrasonic motor with excellent long-term reliability, while at the same time reducing the weight of the motor. It can be realized.

[Brief explanation of drawings]

FIG. 1 is a partially sectional perspective view showing the main components of an ultrasonic motor in an embodiment of the present invention.

FIG. 2: (a) A partially sectional perspective view showing the main components of the annular ultrasonic motor in the first embodiment of the present invention; (b) A partially enlarged sectional view of the annular ultrasonic motor;

FIG. 3 (a) A partially sectional perspective view showing the main components of a toroidal ultrasonic motor according to a second embodiment of the present invention; (b) A partially enlarged sectional view of the same toroidal ultrasonic motor;

FIG. 4 (a) A partial cross-sectional perspective view showing the main components of a toroidal ultrasonic motor according to a third embodiment of the present invention (b) A partial enlarged cross-sectional view of the toric ultrasonic motor according to a third embodiment of the present invention.

FIG. 5 (a) is a partial cross-sectional perspective view showing the main components of an annular ultrasonic motor according to a fourth embodiment of the present invention (b)
Partially enlarged cross-sectional view of the annular ultrasonic motor

[Figure 6] (a)
(b) Partially enlarged sectional view of the annular ultrasonic motor in a fifth embodiment of the present invention, showing main components of the annular ultrasonic motor.

[Fig. 7] Partially sectional exploded perspective view showing the main components of a conventional annular ultrasonic motor.

[Explanation of symbols]

7. Mobile object 8. Moving body beam part 9. Moving body first protrusion 10　Moving body second protrusion 11 Vibrating body 12 Elastic substrate 13 Piezoelectric body

Claims (3)

[Claims] 1. Friction between the vibrating body and the movable body is achieved by bringing a movable body into pressure contact with a vibrating body in which a piezoelectric body is bonded to an elastic substrate, and exciting a traveling wave of bending vibration in the vibrating body. An ultrasonic motor that uses force to move the movable body, the ultrasonic motor comprising: a movable body beam; a movable body first protrusion extending from one end of the movable body beam; and the movable body beam. and a second movable body protrusion extending from the other end of the movable body, the movable body is pressurized with the vibrating body via the first protrusion, and the movable body second protrusion Ultrasonic motor in contact with a vibrating body. 2. A movable body is brought into pressure contact with a vibrating body in which a piezoelectric body is bonded to an elastic substrate, and a traveling wave of bending vibration is excited in the vibrating body, thereby creating friction between the vibrating body and the movable body. An ultrasonic motor that uses force to move the movable body, the ultrasonic motor comprising: a movable body beam; a movable body first protrusion extending from one end of the movable body beam; and the movable body beam. The movable body is constituted by a movable body second protrusion extending from the other end of the movable body, and the movable body is pressurized with the vibrating body via the first protrusion, and the movable body second protrusion is The ultrasonic motor is in contact with the inner circumference of the vibrating body rather than the center. 3. The ultrasonic motor according to claim 1, wherein the moving body is made of a carbon fiber-reinforced resin composite reinforced with at least carbon fibers.