JPH09135587A - Ultrasonic motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to provide uniform contact pressure between a vibrating member and a moving member. SOLUTION: In an ultrasonic motor, a vibrating member 13 is put in pressure contact with a moving member 16 that is connected with an output axle 17 to take out torque from the output axle 17. A motor casing 20 has oil- impregnating bearings 21 and 22 with a moving member in between, and both sides of the output axle 17 is held by the bearings 21 and 22. A pressure spring 18 put in contact with one side of the output axle 17 is used with a sliding member 19 for making the moving member 16 in pressure contact with the vibrating member 13. As a result, an influence of outer load can hardly affect the vibrating member 13, and a uniform contacted state can be held constantly, and an ultrasonic motor with good efficiency and small noises is realized.

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 a driving force by exciting elastic waves using a piezoelectric body such as a piezoelectric ceramic, and more particularly, to a shaft holding of an ultrasonic motor having an output take-out shaft. It relates to a structure and a pressure structure.

[0002]

2. Description of the Related Art In recent years, attention has been paid to ultrasonic motors that use elastic vibration as a driving force by vibrating a vibrating body made of a piezoelectric material.

This ultrasonic motor is constructed as shown in FIG. The output shaft 5 is held in the motor casing 8 via first and second bearings 9 and 10. Inside the motor casing 8, an annular vibrating body 3 is installed via a support member 6 such as felt.

The vibrating body 3 comprises a disc-shaped elastic substrate 1 and a disc-shaped piezoelectric body 2. The disk-shaped elastic substrate 1 has a plurality of protrusions 1a, and the bottom surface thereof has a radial direction 1
Next, the disk-shaped piezoelectric body 2 having an electrode structure capable of exciting a traveling wave of flexural vibration of the third or higher circumferential direction is laminated.

A moving body 4 is attached to the output shaft 5 by press fitting or the like. The moving body 4 and the second bearing 1 are attached.
The pressure spring 7 is interposed between 0. Therefore,
When the vibrating body 3 is driven while the moving body 4 is in pressure contact with the protrusion 1a of the vibrating body 3 by the pressure spring 7, the output shaft 5
Rotates.

FIG. 7 shows the operating principle of rotation of the moving body 4. The piezoelectric body 2 has two sets of drive electrodes, and two AC voltages having a predetermined phase difference are applied to the drive electrodes, respectively. As a result, expansion and contraction vibration is generated in the piezoelectric body 2, and the elastic substrate 1 acts so as to resist expansion and contraction, so that a progressive wave of flexural vibration is excited in the vibration body 3 by the same effect as bimetal.

An arbitrary point on the surface of the vibrating body 3 moves along an elliptical locus by a traveling wave of flexural vibration. The protrusion 1a (omitted in FIG. 7) magnifies the lateral displacement (ζ in FIG. 7) of this elliptical locus. The moving body 4 installed in pressure contact with the protrusion 1a of the vibrating body 3 is driven by frictional force due to the enlarged lateral displacement to rotate.

[0008]

When miniaturizing this ultrasonic motor, the outer diameter of the piezoelectric body 2 as a drive source becomes smaller in proportion to the outer diameter of the vibrating body 3, and the piezoelectric body 2 is stored in the vibrating body 3. Reduced kinetic energy.

Therefore, the motor characteristics greatly change due to the pressurizing mechanism for pressurizing the moving body 4 against the vibrating body and the load fluctuation when the driving force is taken out from the output shaft 5. Further, when a force by an external load is applied in the axial direction of the ultrasonic motor (the direction of biasing by the pressure spring) or in the direction perpendicular thereto, the vibrating body 3
Uneven stress is applied to the elastic substrate 1 (the base portion other than the protrusion 1a) from the protrusion 1a, and the flexural vibration of the vibrating body 3 is disturbed. As a result, unnecessary vibration occurs, the contact state between the vibrating body 3 and the moving body 4 becomes uneven, and the motor efficiency is lowered and noise is easily generated.

Further, for example, when manufacturing a small ultrasonic motor having a diameter of 10 mm, a bearing having a diameter of about 4 mm is required as the first and second bearings 9 and 10. The bearings are expensive and are the main cause of cost increase of ultrasonic motors.

An object of the present invention is to provide an ultrasonic motor which is small in size, realizes uniform pressure contact between the vibrating body and the moving body, can suppress the generation of noise, and is excellent in efficiency. .

[0012]

An ultrasonic motor according to claim 1 forms a vibrating body by coupling a piezoelectric body to an elastic substrate,
In an ultrasonic motor for extracting rotational force from the output shaft by pressurizing and contacting the vibrating body and a moving body coupled to the output shaft, the moving body is centered and both ends of the output shaft are arranged on both sides of the motor casing. An oil-impregnated bearing for holding the movable body is provided, and a pressurizing means for contacting one end of the output shaft to bring the moving body into pressure contact with the vibrating body is provided.

According to another aspect of the ultrasonic motor of the present invention, a piezoelectric body is coupled to an elastic substrate to form a vibrating body, and the vibrating body and a moving body coupled to the output shaft are brought into pressure contact with each other to output the output. In an ultrasonic motor that extracts rotational force from a shaft, an oil-impregnated bearing that holds both ends of the output shaft in a motor casing is provided on both sides of the moving body as a center, and the vibrating body is pressed against the moving body through a holding member. It is characterized in that a pressurizing means is provided.

According to another aspect of the ultrasonic motor of the present invention, a piezoelectric body is coupled to an elastic substrate to form a vibrating body, and the vibrating body and a moving body coupled to the output shaft are brought into pressure contact with each other to output the output. In an ultrasonic motor for extracting a rotational force from one end of a shaft, first and second oil-impregnated bearings for holding both ends of the output shaft in a motor casing are provided on both sides of a moving body as a center. A circular recess is formed in the center of the first oil-impregnated bearing on the one end side of the output shaft, and is engaged with the circular recess of the first oil-impregnated bearing between the vibrating body and the first oil-impregnated bearing. A spherical holding member is provided, and a pressurizing unit is provided that comes into contact with the other end of the output shaft to press the moving body into the circular recess of the first oil-impregnated bearing via the vibrating body and the holding member. It is characterized by that.

Further, the ultrasonic motor according to claim 4 is
In the first and third aspects, the shaft end shape that abuts the pressurizing means of the output shaft is formed into a spherical surface. Further, the ultrasonic motor according to claim 5 is the ultrasonic motor according to claim 2, wherein the output shaft is provided with movement restricting means for contacting the shaft end of the output shaft to restrict the movement of the output shaft in the biasing direction by the pressurizing means. The shape of the shaft end is formed into a spherical surface.

Further, the ultrasonic motor according to claim 6 is
In Claims 4 and 5, the shaft end shape of the output shaft is formed into a spherical surface, and the receiving surface with which one end abuts is formed into a spherical concave portion.

Further, the ultrasonic motor according to claim 7 is
In any one of claims 1 to 6, the contact width of the oil-impregnated bearing with the output shaft is set to 1 mm or less. Therefore, in the ultrasonic motor according to the present invention, the output shaft is held not by the bearing but by the oil-impregnated bearing, and the shaft end of the output shaft is used as a fulcrum to apply pressure from one end on the output side of the output shaft or the vibrating body side to vibrate. Since the body and the moving body are in pressure contact, the output shaft is held by a bearing, the moving body is pressurized, and the vibrating body and the moving body are in pressure contact. Therefore, not only the radial position regulation of the output shaft but also the axial position regulation can be performed, so that the output extraction shaft can be held more stably and a more uniform pressure distribution can be achieved. It is possible to pressurize the vibrating body and the moving body. Even when an external load is applied in the axial direction of the ultrasonic motor or in the direction perpendicular to the axial direction, the output extraction shaft rarely causes shaft runout, and the effect of load fluctuations on the vibrator can be reduced. It becomes possible and the load resistance of the vibration body is improved. That is, even when the above-mentioned external load is applied, a uniform contact state between the vibrating body and the moving body can be maintained.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS. [First Embodiment] FIG. 1 shows an ultrasonic motor according to the first embodiment.

As shown in FIG. 1, a small ultrasonic motor having a diameter of, for example, 10 mm is constructed by pressing the output shaft 17 with a pressure spring 18 to bring the vibrating body 13 and the moving body 16 into pressure contact with each other. is there.

The output shaft 17 having a spherical end portion 17a at a position opposite to the output take-out is pressed by a pressure spring 18 via a sliding member 19 made of polyacetal resin, and the output shaft 17 It is configured to receive a thrust load at the spherical surface of the shaft end.

The output shaft 17 is held by the motor casing 20 via a first oil-impregnated bearing 21 and a second oil-impregnated bearing 22. That is, the radial position regulation of the output shaft 17 is set to 2
By performing the oil-impregnated bearings 21 and 22 at some positions and restricting the axial position by the shaft end spherical surface of the output shaft 17, the vibrating body 13 and the moving body 16 can be brought into uniform pressure contact. As a result, a stable driving force can be taken out from the output shaft 17.

Specifically, the vibrating body 13 has a plurality of rectangular protrusions 11a. A disc-shaped piezoelectric body 12 having an electrode structure capable of exciting a traveling wave of flexural vibration of primary in the radial direction and tertiary in the circumferential direction or more is bonded to the bottom surface of a disc-shaped elastic substrate 11 made of brass or the like. In order to support the vibrating body 13, the vibrating body 13 is provided with a holding member 14 having a spherical shape and made of, for example, polyphenylene sulfide side resin.
The vibrating body 13 is supported by a support member 15 made of, for example, polyphenylene sarside resin and having a circular recess at the inner center.

The moving body 16 is made of, for example, a composite of 30% by weight of carbon fiber and 70% by weight of polyphenylene sulfide resin, and is integrally molded with the output shaft 17 so as to be coupled to the output shaft 17. It is configured.

The first oil-impregnated bearing 21 and the second oil-impregnated bearing 22 are
For example, a sintered body of copper alloy or the like impregnated with lubricating oil is used, and it is installed by press-fitting it into the motor casing 20 that houses the motor.

In the above structure, the tightening member 23 with a screw is used to press the pressure spring 18, and the pressing force can be adjusted by changing the screwing amount. The tightening member 23 with a screw is not always necessary, and the portion for receiving the pressure spring 18 can be formed integrally with the motor casing 20.

The holding member 14 having a spherical shape was press-fitted into the vibrating body 13 and the vibrating body 13 was supported by the supporting member 15. However, the vibrating body supporting method is not limited to this, and FIG. As shown, it is also possible to support the vibrating body 13 using a support member 26 such as felt.

[Second Embodiment] FIG. 3 shows an ultrasonic motor according to the second embodiment. This ultrasonic motor
The vibrating body 33 is pressed by a pressure spring 38, and the vibrating body 33 and the moving body 36 are brought into pressure contact with each other.
It is a small ultrasonic motor of 0 mm.

By forming the shaft end portion 37a of the output shaft 37 opposite to the output take-out into a spherical shape and pressing the vibrating body 33 with the pressing spring 38, a sliding member 39 made of, for example, polyacetal resin is used. The thrust load is applied to the shaft end spherical surface of the output shaft 37. In addition, the output shaft 37
Is a configuration in which a motor casing 40 accommodating a motor holds a first oil-impregnated bearing 41 at a position opposite to a contact surface of a vibrating body 33 and a second oil-impregnated bearing 42 at a position opposite to a contact surface of a moving body.

More specifically, the vibrating body 33 has a plurality of rectangular-shaped protrusions 31a, and has a bottom surface of a disk-shaped elastic substrate 31 made of, for example, stainless steel or the like. Is formed by adhering a disk-shaped piezoelectric body 32 having an electrode structure capable of exciting the traveling wave of, while holding the vibrating body 33 and restricting the position of the pressure spring 38,
A holding member 34 made of, for example, polyacetal resin or the like, which has a convex portion in the radial direction in order to make pressure contact with the moving body 36.
Is press-fitted to form a vibrating body.

The moving body 36 is formed, for example, by injection-molding a composite of 30% by weight of carbon fiber and 70% by weight of polyphenylene sulfide resin.
It is configured to be connected to the output shaft 37 by being press-fitted into the output shaft 7.

The first oil-impregnated bearing 41 and the second oil-impregnated bearing 42 are
As in the case of the first embodiment, for example, a sintered body of copper alloy or the like impregnated with lubricating oil is used, and it is installed by press-fitting it into the motor casing 40 that houses the motor.

Also, unlike the [first embodiment], the [second embodiment] applies pressure from the side of the vibrating body 33 so that the moving body 3 is caused by a coaxial shift between the bearings or the like.
The vibrating body 33 is moved to the moving body 36 regardless of the inclination of 6,
It is possible to always make uniform contact.

Further, since the vibrating body 33 and the moving body 36 are brought into pressure contact with each other, it is possible to have a function of supporting the vibrating body 33, and FIG. 1 of the [first embodiment] is shown. The support member 15 shown in FIG. 2 is unnecessary, and the number of parts can be reduced.

Further, by applying pressure from the vibrating body 33 side, it is possible to effectively utilize the storage space,
It is possible to reduce the axial length of the ultrasonic motor and realize a more compact ultrasonic motor.

[Third Embodiment] FIG. 4 shows an ultrasonic motor according to the third embodiment. This ultrasonic motor
The output shaft 47 is pressed by a pressure spring 48, and the vibrating body 13 and the moving body 46 are brought into pressure contact with each other.
It is a small ultrasonic motor of 0 mm.

The output shaft 47 in which the shaft end portion 47a opposite to the output take-out is formed in a spherical shape is provided with a sliding member 49 made of, for example, polyacetal resin, having a spherical concave portion 49a corresponding to this spherical shape. The pressure is applied by the pressure spring 48, and a thrust load is applied to the shaft end spherical surface of the output shaft 47. The output shaft 47 is held by the motor casing 20 via the first oil-impregnated bearing 21 and the second oil-impregnated bearing 22.

More specifically, the vibrating body 13 has a diameter similar to that of the first embodiment, which has a plurality of rectangular protrusions 11a, and is formed on the bottom surface of a disk-shaped elastic substrate 11 made of, for example, brass. It is configured by bonding a disk-shaped piezoelectric body 12 having an electrode structure capable of exciting a traveling wave of flexural vibration of the first-order direction and the third-order circumferential direction or more, and in order to support the vibrator 13, a spherical shape is formed. The holding member 14 made of, for example, polyphenylene sulfide side resin is press-fitted, and the vibrating body 13 is supported by the support member 15 made of, for example, polyphenylene sulfide side resin having a circular recess.

The moving body 46 is made of, for example, 30% by weight of carbon fiber and 70% by weight of polyetheretherketone resin composite, and is joined to the output shaft 47 by being integrally injection-molded on the output shaft 47. It is configured.

The first oil-impregnated bearing 21 and the second oil-impregnated bearing 22 are
As in the case of the first embodiment, a sintered body of copper alloy or the like impregnated with lubricating oil is used, and is installed by press-fitting it into the motor casing 20.

In the above structure, in order to press the pressure spring 48, the tightening member 23 with a screw is used as in the case of the [first embodiment], and the pressing amount is changed by changing the screwing amount. The pressure can be adjusted. This tightening member 23 with a screw is not always necessary, and the pressing spring 4
It is also possible to integrally form the part for receiving 8 with the motor casing 20.

In the above structure, the holding member 14 having a spherical shape is press-fitted into the vibrating body 13 to support the supporting member 15.
Although the vibrating body 13 is supported by, the supporting method of the vibrating body is not limited to this, and the vibrating body 13 is supported by using a supporting member such as felt as in the [first embodiment]. It is possible as well.

In the third embodiment, the first
Of the present invention, the centering effect of the output shaft 47 can be enhanced and the pressure concentration on the sliding member 49 can be alleviated, so that an external load in the radial direction can be applied to the output shaft 47. Even when it is applied, the output shaft 47 can be held with a larger restricting force and at the same time, the sliding member 4 can be held.
9 wear can be reduced.

The ultrasonic motor of the [third embodiment] and the ultrasonic motor of the [first embodiment] are selectively used according to the pressure applied to the vibrating body and the moving body under pressure. In addition, this [third embodiment] can be applied to the ultrasonic motor of the [second embodiment], and the same operational effect as the [third embodiment] can be obtained. It goes without saying that you can get it.

[Fourth Embodiment] FIG. 5 shows an ultrasonic motor according to the fourth embodiment of the present invention. This ultrasonic motor is a small ultrasonic motor having a diameter of 10 mm, which is configured by pressing the output shaft 57 with a pressing spring 58 to bring the vibrating body 33 and the moving body 56 into pressure contact with each other.

The output shaft 57 having a shaft end portion 57a opposite to the position where the output is taken out and formed into a spherical shape is pressed by a pressure spring 58 via a sliding member 59 made of, for example, polyacetal resin, and the output shaft 57 It is configured to receive a thrust load at the spherical surface of the shaft end. The output shaft 57 is held by an oil-impregnated bearing, and the first oil-impregnated bearing that also functions as a supporting member of the vibrating body 33 is provided in the motor casing 50 that houses the motor at a position opposite to the contact surface of the vibrating body 33. 51, the second oil-impregnated bearing 52 is installed at a position opposite to the contact surface of the moving body 56.

In the above structure, the sliding member 59 having a shape different from that of the first embodiment is used. However, by restricting the position of the pressure spring 58 at the inner peripheral portion, In the first embodiment], it is possible to eliminate the contact resistance between the outer peripheral portion of the pressure spring 18 and the inner peripheral portion of the sliding member 19, and the pressure spring can be pressed by the vibrating body and the moving body. Since the pressure spring uniformly deforms when it contracts, it is possible to prevent the pressure spring from twisting, falling, and the like, and more uniform pressure contact between the vibrating body and the moving body can be performed.

More specifically, the vibrating body 33 has a plurality of rectangular-shaped protrusions 31a, as in the case of the second embodiment. It is configured by adhering a disk-shaped piezoelectric body 32 having an electrode structure capable of exciting a traveling wave of bending vibration of primary and circumferential third or higher order, and has a spherical shape to support the vibrating body 33. For example, a holding member 54 made of polybutylene terephthalate resin containing glass fiber is press-fitted, and the first oil-impregnated bearing 21 having a circular recess is used to form the vibrating body 1.
Supported 3.

The moving body 56 is formed, for example, by injection-molding a composite of 30% by weight of carbon fiber and 70% by weight of polyether sulfone resin, and press-fitted into the output shaft 57 to form an output shaft. It is configured to be connected to 57.

The first oil-impregnated bearing 51 and the second oil-impregnated bearing 52 are
For example, a sintered body of copper alloy or the like impregnated with lubricating oil was used, and it was installed by press-fitting it into a motor casing 50 that houses a motor.

In the above structure, unlike the first embodiment, the oil-impregnated bearing 51, which also has the function of supporting the vibrating body 33, supports the vibrating body 33. Form], the support member 15 shown in FIG.
The number of parts can be reduced. Moreover, since the vibrating body 33 is supported by the contact between the spherical surface of the holding member 54 and the circular recess of the first oil-impregnated bearing 51, it is possible to prevent the vibrating body 33 from being displaced, and to move with the vibrating body 33. More uniform pressure contact with the body 56 can be achieved.

[Fifth Embodiment] Next, an ultrasonic motor according to the fifth embodiment will be described. The configuration of the main part is the same as that of the [first embodiment] shown in FIG. 1, but there are several types of contact widths between the first oil-impregnated bearing 21 and the second oil-impregnated bearing 22 with the output shaft 17. Diameter 10mm
The small ultrasonic motor of
3 and the moving body 16 are brought into pressure contact with each other, and the pressing force is 300 g.
set to f.

The first oil-impregnated bearing 21 and the second oil-impregnated bearing 22 are
For the sake of convenience, oil-impregnated bearings having the same thickness were used, and tapered portions were provided at both ends of the inner surface of the oil-impregnated bearing, and the contact width with the output shaft was changed by changing the degree of this taper.

The power consumption when this small ultrasonic motor was rotated at a rotation speed of 600 rpm was measured. The results are shown in [Table 1] below.

[0054]

[Table 1]

As shown in the results of [Table 1], when the contact width of the oil-impregnated bearing is larger than 1.0 mm, the power consumption of the motor for obtaining the same rotation speed increases. It was This is because when the contact width of the oil-impregnated bearing with the output shaft becomes larger than 1.0 mm, the contact resistance between the output shaft and the oil-impregnated bearing increases. Therefore, the load resistance when the output shaft rotates increases, and it is considered that more power is required to overcome the load resistance and obtain the same rotation speed, and the power consumption of the motor increases. .

From the above results, if the contact width of the oil-impregnated bearing with the output shaft is set to 1.0 mm or less, a small ultrasonic motor with low power consumption can be realized. In addition, although the ultrasonic motor having the configuration of the [first embodiment] has been described in the [fifth embodiment], the [second embodiment] to
It is needless to say that the present invention can be applied to the ultrasonic motor of [Fourth Embodiment] and the same operational effect as that of [Fifth Embodiment] can be obtained.

Although specific embodiments have been described above, the polyacetal resin is used as the sliding member that receives the thrust load on the shaft end spherical surface of the output shaft in each embodiment, but the present invention is not limited to this. However, a material having a small friction coefficient and excellent wear resistance is desirable, and a polyacetal resin containing polytetrafluoroethylene powder, or an oil-containing polyacetal resin containing 5 to 8% by weight of a lubricant, or graphite powder. It is likewise possible to use engineering plastics containing.

Further, in each of the embodiments, the oil-impregnated bearing for holding the output shaft is a copper alloy sintered body impregnated with lubricating oil, but the invention is not limited to this. It is also possible to use a metal-based oil-impregnated bearing obtained by impregnating the sintered body with lubricating oil, or a plastic-type oil-impregnated bearing in which phenol resin or polyacetal resin is impregnated with lubricating oil or a lubricant.

[0059]

As described above, according to the present invention, by virtue of devising the holding mechanism for the output shaft and the pressurizing mechanism for the vibrating body and the moving body, the vibrating body is less likely to be affected by an external load, and the vibrating body is less affected. It becomes possible to maintain a uniform contact state between the movable body and the moving body, and as a result, it is possible to provide a small ultrasonic motor that suppresses the generation of noise and is efficient, and at a low cost.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an ultrasonic motor according to a [first embodiment].

FIG. 2 is a cross-sectional view showing another configuration according to the [first embodiment].

FIG. 3 is a cross-sectional view of an ultrasonic motor according to a second embodiment.

FIG. 4 is a sectional view of an ultrasonic motor according to a third embodiment.

FIG. 5 is a sectional view of an ultrasonic motor according to a fourth embodiment.

FIG. 6 is a sectional view of a conventional ultrasonic motor.

FIG. 7 is an explanatory diagram of the operating principle of the ultrasonic motor.

[Explanation of symbols]

 1, 11, 31 Elastic substrate 1a, 11a, 31a Projection body 2, 12, 32 Piezoelectric body 3, 13, 33 Vibrating body 4, 16, 36, 46, 56 Moving body 5, 17, 37, 47, 57 Output shaft 6,15,26 Support member 7,18,38,48,58 Pressure spring 8,20,30,40,50 Motor casing 9 1st bearing 10 2nd bearing 14,34,54 Holding member 19,39,49 , 59 Sliding member 21, 41, 51 First oil-impregnated bearing 22, 42, 52 Second oil-impregnated bearing 23 Tightening member

Claims (7)

[Claims] 1. An ultrasonic wave in which a piezoelectric body is coupled to an elastic substrate to form a vibrating body, and the vibrating body and a moving body coupled to the output shaft are brought into pressure contact with each other to extract a rotational force from the output shaft. In the motor, an oil-impregnated bearing for holding both ends of the output shaft in the motor casing is provided on both sides of the moving body as a center, and a pressing means for contacting one end of the output shaft with the moving body under pressure contact with the vibrating body is provided. Ultrasonic motor provided. 2. An ultrasonic wave for extracting a rotational force from the output shaft by forming a vibrating body by connecting a piezoelectric body to an elastic substrate and bringing the vibrating body and a moving body connected to the output shaft into pressure contact with each other. In the motor, an oil-impregnated bearing for holding both ends of the output shaft in the motor casing is provided on both sides of the moving body as a center, and a pressure means for pressing the vibrating body to the moving body through a holding member is provided. Sonic motor. 3. A vibrating body is formed by coupling a piezoelectric body to an elastic substrate, and the vibrating body and a moving body coupled to the output shaft are brought into pressure contact with each other to extract a rotational force from one end of the output shaft. In the ultrasonic motor, the first and second oil-impregnated bearings for holding both ends of the output shaft in the motor casing are provided on both sides of the moving body as a center,
A circular recess is formed in the center of the first oil-impregnated bearing on the one end side of the output shaft of the oil-impregnated bearing, and the circular recess is formed between the vibrating body and the first oil-impregnated bearing. A spherical holding member that engages with the circular recess is provided, and the moving body is brought into contact with the other end of the output shaft to press-contact the circular recess of the first oil-impregnated bearing through the vibrating body and the holding member. An ultrasonic motor provided with a pressurizing means. 4. The ultrasonic motor according to claim 1, wherein the shaft end shape which comes into contact with the pressurizing means of the output shaft is formed into a spherical surface. 5. A movement restricting means for contacting the shaft end of the output shaft to restrict the movement of the output shaft in the urging direction by the pressing means is provided, and the shape of the shaft end of the output shaft is formed into a spherical surface. Item 2
The described ultrasonic motor. 6. The ultrasonic motor according to claim 4, wherein a receiving surface, which is in contact with one end of the output shaft having a spherical end shape, is formed into a spherical recess. 7. The ultrasonic motor according to claim 1, wherein the contact width of the oil-impregnated bearing with the output shaft is set to 1 mm or less.