JPH0449874A - Ultrasonic wave motor - Google Patents

Abstract

PURPOSE:To simplify a manufacturing process due to the reduction of the number of the component parts of a moving body and the omission of a bonding process, and lighten the weight of a motor by forming the moving body with a fiber reinforced resin complex, and by realizing uniform contact to improve the efficiency of the motor. CONSTITUTION:A moving body 24 is formed with a fiber reinforced resin complex in order to enhance rigidity by using reinforcing fibers at the same time as mechanical strength insufficient with resin component only is made up for. Accordingly, the complex can be easily molded with the use of a metallic mold, and the weight of the moving body 24 can be reduced. Besides, face correcting effect for absorbing the swell of contact surfaces between an oscillating body and the moving body is obtained, and flatness can be secured, and so the efficient transmission of the progressive wave of deflection oscillation due to the oscillating body, to the moving body, and stable working are obtained. As a result, a manufacturing process can be simplified due to the reduction of the number of the component parts of the moving body and the omission of a bonding process, and the weight of a motor can be lightened, and characteristic can be stabilized.

Description

[Detailed Description of the Invention] Industrial Field of Application 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.More specifically, a moving body of an ultrasonic motor. Conventional technology In recent years, ultrasonic motors that excite elastic vibrations in a vibrating body made of a piezoelectric material and use this as a driving force have been attracting attention. Explain the technology.

FIG. 7 is a partially cutaway perspective view of a conventional annular ultrasonic motor. The vibrating body 7 is a movable body composed of an elastic body 5 and a wear-resistant friction material 6 bonded together, and although it is installed in pressurized contact with the vibrating body 4, FIG. 4 is a partially cutaway perspective view of a disc-shaped ultrasonic motor. In the figure, 4a is a disc-shaped piezoelectric body 3a bonded to the bottom surface of a disc-shaped elastic substrate 2a having a plurality of protrusions 1a. The vibrating body 7a is a movable body in which a wear-resistant friction material 6a is bonded to an elastic body 5a. 5.5a
Conventionally, metals such as iron and stainless steel have been used as the material for the ultrasonic motor. Although not shown in the drawings, two sets of drive electrodes are formed on the piezoelectric body 3.3a of the moving body 7. The piezoelectric body 3.3a undergoes expansion and contraction vibration, and the elastic substrates 2, 2a act to resist expansion and contraction, so even if a traveling wave of bending vibration is excited in the vibrating body 4.4a, it will not vibrate due to the same effect as a bimetal. Any point on the surface of the body 4.4a moves in an elliptical trajectory due to the traveling wave of the bending vibration.The protrusions 1 and 1a magnify the displacement in the lateral direction (component in the direction in which the traveling wave travels) of this elliptical trajectory. The movable body 7.7a installed in pressure contact with the protrusion 1.1a of the vibrating bodies 4, 4a is frictionally driven by the enlarged lateral displacement and rotates.The problem to be solved by the invention. An ultrasonic motor excites a traveling wave of bending vibration with an amplitude of several microns in a vibrating body made of a piezoelectric material and an elastic substrate.
The lateral displacement caused by this traveling wave is magnified by the protrusion, and the motor drives the moving body installed in pressure contact with the tip of the protrusion. In order to efficiently transmit the traveling wave of bending vibration caused by the vibrating body to the moving body when the moving body is constructed by coupling it to an elastic body such as The material needs to have enough rigidity to prevent large elastic deformation in the lateral direction (the direction of travel of the traveling wave), and the vibrating body and moving body must be in surface contact with each other under pressure. In order to efficiently transmit the force to the vibrating body, it is necessary to achieve uniform contact under pressure contact (if the contact surface is made of a highly rigid material such as metal or ceramic, The elastic deformation in the vertical direction becomes small, making it difficult to achieve uniform contact, which results in noise generation and a decrease in motor efficiency.

On the other hand, when a moving body is constructed by bonding a wear-resistant friction material to an elastic body such as metal as described above, kj
i! When the thickness of the friction material is made thinner, the force length varies depending on the motor's pressurizing force.This may cause noise and a decrease in motor efficiency. This force is thought to be caused by the fact that elastic deformation in the longitudinal direction becomes smaller, making it impossible to achieve uniform contact, and increasing the mechanical quality factor (Q,) against unnecessary vibrations (which is a major problem in practice). 12 As mentioned above, when a moving body is constructed by bonding a wear-resistant friction material to an elastic body such as metal, the weight of the moving body increases because the metal material has a high specific gravity, and as a result, the motor As the total weight increases, there is a limit in reducing the weight of the ultrasonic motor.The present invention has been made in view of this problem, and improves motor efficiency by achieving uniform contact. The purpose is to simplify the manufacturing process by reducing the number of parts and omitting the bonding process, and at the same time to reduce the weight of the motor.

Means for solving the problems The present invention
In an ultrasonic motor that moves the movable body by bringing the movable body into pressure contact and exciting a traveling wave of flexural vibration in the vibrating body, the movable body is made of a fiber-reinforced resin composite.

By constructing the action moving body from a fiber-reinforced resin composite,
The reinforced fibers can increase the rigidity of the frictional contact surface in a small range, while at the same time increasing the elasticity in a large range, which has a surface correction effect that absorbs the waviness of the contact surface between the vibrating body and the moving body. In addition, by constructing the moving body from a fiber-reinforced resin composite, it is possible to efficiently transmit the traveling wave of bending vibration from the vibration body to the moving body. Compared to a configuration in which a friction material is bonded to a metal elastic body, the number of moving body parts can be reduced, and at the same time, the manufacturing process can be simplified by omitting the bonding process.The moving body is constructed from a fiber-reinforced resin composite. By doing so, the weight of the moving body can be reduced compared to a structure in which a friction material is combined with a metal elastic body, and the weight of the ultrasonic motor can therefore be reduced. One embodiment will be described in detail.

(First Embodiment) FIG. 1 shows the appearance of the main parts of an annular ultrasonic motor which is a first embodiment of the ultrasonic motor of the present invention.

FIG. 2 is a partially enlarged side view of the main components of an ultrasonic motor according to an embodiment of the present invention. In the figure, reference numeral 23 indicates the bottom surface of an elastic substrate 21 made of stainless steel and having a plurality of protrusions 20. 24 is a moving body made of a fiber-reinforced resin composite, and this moving body 24 is installed in pressure contact with the vibrating body 23. Therefore, in the ultrasonic motor, the lateral displacement due to the traveling wave of the bending vibration excited by the vibrating body 23 is magnified by the plurality of protrusions 20, and the moving body 24, which is placed in pressure contact with each other, is expanded. Even if the drive is performed,
The moving body 24 is moved by the load torque.
If the contact surface of the contact surface has enough rigidity to prevent large elastic deformation in the lateral direction, an appropriate mechanical strength is required to transmit the driving force of the ζ motor to the outside.

In this example, the moving body 24 is constructed of a fiber-reinforced resin composite in order to increase the rigidity by using reinforcing fibers and at the same time compensate for the insufficient mechanical strength of the resin alone. Table 1 for the ultrasonic motor in the example: Moving body 24 and vibrating body 2
In this embodiment, the movable body 24 is made of a fiber-reinforced resin composite, so that the bonding process for bonding the friction material to the metal elastic body as in the conventional example can be avoided. It is possible to easily mold the movable bodies 24 and 34 using a mold using a method such as injection molding or compression molding. It is possible to reduce the weight of the moving body 24.34 to at least 1/4 or less compared to a moving body of the same size constructed by bonding a friction material to a stainless steel elastic body. A surface correction effect that absorbs the undulations of the contact surface with the moving body can be obtained, and flatness can be ensured. Traveling waves of bending vibrations caused by the vibrating body can be efficiently transmitted to the moving body, and stable operation can be achieved. 9 (Second Embodiment) Next 1 The second embodiment is shown in FIG. This embodiment is an ultrasonic motor that is not annular but a disc type.

By bonding a piezoelectric body 32 to the bottom surface of a stainless steel disc-shaped elastic substrate 31 having a plurality of protrusions 30,
Although the disc-shaped vibrating body 33 is configured, it is also composed of a disc-shaped moving body 34ζ, which is made of a fiber-reinforced resin composite, and this moving body 34 has a rotating shaft 3 made of stainless steel.
The movable body 34 into which 5 is press-fitted is brought into pressure contact with the vibrating body 33. By constructing the movable body 34 from a fiber-reinforced resin composite as described above, the same effects as in the first embodiment can be obtained. The stiffness required for this moving body varies depending on the pressing force of the ultrasonic motor.The stiffness of the moving body can be adjusted by adjusting the content of reinforcing fibers contained in the fiber-reinforced resin composite. can.

(Third example) A third embodiment is shown in FIG.

First, a piezoelectric body 42 is bonded to the bottom surface of a stainless steel circular elastic substrate 41 having a plurality of protrusions 40 to form a circular vibrating body 43. As shown in the figure, the surface of the protrusions 40 is A movable body 44 made of an annular fiber-reinforced resin composite whose inner and outer end surfaces do not come into contact with each other is obtained. By installing this movable body 44 in pressurized contact with the vibrating body 43, Even if an annular ultrasonic motor is configured, by configuring the movable body as described above, it is possible to avoid mechanical damage to the movable body contact surface due to the corners of both end faces of the protrusion 40. It is possible to obtain a more uniform frictional contact condition, which results in more efficient output transmission.It is possible to improve motor efficiency in this way. In addition to the above, for example, the width of the protrusion 40 is defined as W as shown in Fig. 5. Then, even if the outer circumferential part W/4 and the inner circumferential part W/4 do not contact, and the protrusion and the movable body contact at the center part W/2 of the protrusion, Q. By chamfering the inner circumferential part W/8 without contacting the part W/2, the inner circumferential side 3 of the protrusion
Even if the protrusion and the movable body are in contact at W/8, α(c) shows that the protrusion does not contact the inner circumference W/2, and by chamfering the outer circumference W/8, the protrusion The structure is such that the protrusion and the movable body are in contact at 3W/8 on the outer circumferential side, and the same effect as described above can be obtained regardless of the shape. Relief width Table 1 Force that is not particularly limited (force that varies depending on the width of the protrusion (a minimum clearance width of about 0.1 mm should be provided) Moreover, it can be easily molded using a mold using methods such as injection molding and compression molding, and it is possible to reduce the weight of the moving body to at least 1/4 or less. 4th Example) FIG. 6 shows a fourth example.

As a fourth embodiment, first, a piezoelectric material 5 is attached to the bottom surface of a stainless steel disk-shaped elastic substrate 51 having a plurality of protrusions 50.
2, the disk-shaped vibrating body 53 is constructed. As shown in FIG. A mobile body 54 made of a fiber-reinforced resin composite was obtained. This mobile body 54
A disc-type ultrasonic motor is constructed by press-fitting a rotating shaft 55 made of stainless steel into the rotary shaft 55 and installing the movable body 54 in pressure contact with the vibrating body 53. In this embodiment, the friction material It does not require an adhesion process, and it can be easily molded using a mold by injection molding, compression molding, etc., and the weight of the moving body can be reduced to at least 1/4 or less. The content of the reinforcing fibers contained in the fiber-reinforced resin composite that constitutes the moving body can be adjusted according to the pressing force of the ultrasonic motor, and the rigidity can be further increased. It is also possible to combine the above fibers with inorganic fillers such as graphite powder, tetrafluoroethylene powder, molybdenum sulfide powder, and graphite fluoride powder. Effects of the Invention The ultrasonic motor of the present invention can be used as a moving object. By constructing the motor from a fiber-reinforced resin composite, it is possible to simplify the manufacturing process by reducing the number of moving body parts and omitting the adhesion process, reducing the weight of the 4-ton motor and stabilizing its characteristics.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view showing the main components of an annular ultrasonic motor, which is an embodiment of the ultrasonic motor of the present invention, partially in section, and the main components of a disk-type ultrasonic motor partially in section. Medicine 4th
Figure 5 shows a strabismus doctor showing an example of the shape of the movable body in the embodiment shown in Figure 4. Figure 6 is an exploded perspective view showing a partial cross-section of the main components of a disc-type ultrasonic motor, which is another embodiment. In the exploded perspective view shown in partial cross section, the arms 1, 1a, 20, 30.
a, 21, 31.41, 51... elastic substrate 3, 3a
, 22, 32. 42, 52... piezoelectric body 4, 4a, 23
, 33.43, 53... Vibrating body 5, 5a... Elastic body 6, 6a... Friction material, 7.7a... Moving body 24, 34, 44, 54... Moving body 35, 55... Name of rotational agent Patent attorney Shigetaka Awano and one other person Figure Figure 23 Still Body

Claims (2)

[Claims] (1) In an ultrasonic motor that moves a movable body by bringing a movable body into pressure contact with a vibrating body having a piezoelectric body coupled to an elastic substrate and exciting a traveling wave of bending vibration to the vibrating body, the moving body An ultrasonic motor characterized by having a body made of a fiber-reinforced resin composite. (2) A movable body is brought into pressure contact with a vibrating body in which a piezoelectric body is coupled to an elastic substrate having a plurality of protrusions, and the movable body is moved by exciting a traveling wave of bending vibration in the vibrating body. In the ultrasonic motor, the movable body is made of a fiber-reinforced resin composite, and the inner circumference and the outer circumference of the protrusion surface of the vibrating body do not come into contact with each other. motor.