JPH03195379A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To prevent generation of unnecessary slip oscillation by a method wherein a member for supporting an oscillator on another member is supported so as not to block the rotation about the node of bending oscillation. CONSTITUTION:The oscillator 12 of an ultrasonic motor is constituted of a longitudinal oscillator 4 and a bending oscillator 11 where the bending oscillator 11 is formed of an elastic body 5 and a piezoelectric body 6, bonded to the upper surface of the elastic body 5. A supporting part 5a, projected into the widthwise direction of the bending oscillator 11, is provided integrally with the elastic body 5 at the position of the node of the bending oscillation of the bending oscillator 11. A supporting member 14, equipped with a flange, is fixed or fitted to the outer periphery of the projected supporting part 5a while the projected supporting part 5a is fitted to the engaging notch 7b of a holding body 7, fixed to a supporting frame 1 through a screw 10, whereby the bending oscillator 11 is fixed to the supporting frame 1. According to this method, the oscillator 12 can be supported without blocking the oscillation of the bending oscillator 11 whereby a highly efficient motor may be manufactured.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention combines an ultrasonic motor, more specifically a bending vibrator and a longitudinal vibrator, and attaches the longitudinal vibrator to the bending vibration node of the bending vibrator. The present invention relates to the structure of an ultrasonic motor.

[Prior Art] As is well known, ultrasonic motors, which have been attracting attention recently, have the characteristics of being easy to drive at low speeds and being able to obtain high torque output, and some motors have already been commercialized. There is. However, this commercialized ultrasonic motor is a rotary type motor, and a small linear type motor that has a high degree of design freedom and can easily be converted into a rotary type motor is still commercially available. has not been standardized. The reason for this is that it is difficult to manufacture a small linear type ultrasonic motor with high efficiency and high output.
In the traveling-wave linear ultrasonic motor proposed in Publication No. 1, it is necessary to use a closed-loop bending vibrator in order to efficiently generate a traveling wave, and the vibrator becomes very large. The support mechanism for this vibrator is also complicated, and the efficiency of the motor itself is only a few percent, which does not necessarily result in a small linear type ultrasonic motor with high efficiency. Furthermore, in the case of a linear type ultrasonic motor that combines the bending resonance of a plate and the longitudinal resonance vibration in the longitudinal direction of the plate, as disclosed in JP-A-63-277477, the bending resonance of the plate and the longitudinal resonance vibration of the plate are combined. Unless the resonant frequencies of the longitudinal resonances match, a highly efficient motor cannot be realized, and the size and shape of the motor are limited. Therefore, it has not been easy to downsize and increase efficiency. Furthermore, because this motor uses the transverse effect of the piezoelectric body (the direction of vibration is perpendicular to the direction of voltage application) to generate the frictional force, it is not possible to increase the crimping force. However, it also has the disadvantage of not being able to generate a large driving force.

Therefore, in order to eliminate the above-mentioned drawbacks of the conventional ultrasonic motor of this type, the present applicant has generated a resonant bending standing wave in a plate-shaped bending vibrator to which a piezoelectric material is attached, and at the position of the bending vibration node. , by providing a vertical vibrator made of a laminated piezoelectric material that vibrates in a direction perpendicular to the neutral axis of bending vibration, and by shifting the phase of the bending vibration and the longitudinal vibration generated by the longitudinal vibrator by 90 degrees, the tip of the vertical vibrator We have previously proposed a small linear type ultrasonic motor that generates elliptical vibrations in order to prevent a moving body crimped onto the tip of a vertical vibrator from moving in a predetermined direction (Japanese Patent Application No. No. 195767).

According to this ultrasonic motor, the motor efficiency is high and it can be configured to be thinner, making it extremely useful. Since this small linear type ultrasonic motor is small, it is possible to arrange them in a circular manner, or to make the bending vibrator itself into an annular shape or a disk shape.
It is easy to create a small rotary ultrasonic motor, and since a longitudinal vibrator of laminated piezoelectric material is used in the direction in which the crimping force is applied to generate frictional force, it can generate a large driving force despite its small size. There are many benefits of being able to generate

[Problem to be Solved by the Invention] Incidentally, in an ultrasonic motor using a resonant standing wave, the mounting structure of the flexural vibrator to the fixed support frame is generally designed to improve motor efficiency and stabilize output. This is an important requirement, but since the vibrator emits standing wave resonance vibration, in order to fix it without damaging the vibration as much as possible, it must be configured to support the nodes of standing wave vibration. That's a good thing.

However, the present applicant first proposed (Patent Application No. 1195767)
In the ultrasonic motor (No.), the driving force uses minute pendulum vibrations generated around the nodes of bending vibration, so
If the nodes are completely fixed, the minute pendulum vibrations around the nodes due to bending resonance will also stop, resulting in no movement at all.

In addition, in this ultrasonic motor, the nodes of bending vibration are supported by bearings that allow minute vibrations around the nodes, so the relative relationship between the supported part of the bending vibrator and the supporting part is These micro-frictional vibrations not only reduce motor efficiency due to friction loss, but also cause non-uniform slip vibrations due to non-uniform friction, which in turn causes unpleasant audible noise. It is also accompanied by

An object of the present invention is to support the flexural oscillator so as to minimize the efficiency loss of the flexural oscillator, in order to eliminate the above-mentioned defects in the ultrasonic motor proposed by the present applicant.
To provide an ultrasonic motor which is small in size, highly efficient, provides stable high output, and does not generate unpleasant audible sounds by preventing the generation of unnecessary slip vibrations due to this support.

[Means and effects for solving the problems] The ultrasonic motor of the present invention includes a rod-shaped or plate-shaped bending vibrator that excites bending standing wave vibrations, and a bending vibrator that excites the standing wave vibrations on the bending vibrator. A vibrator consisting of at least one longitudinal vibrator installed at a node position and vibrating in a direction perpendicular to the neutral plane of bending standing wave vibration; It is equipped with a rail configured to allow relative movement only in the direction,
In the ultrasonic motor that moves the rail and the vibrator relative to each other by a composite vibration of the bending vibration of the bending vibrator and the longitudinal vibration of the longitudinal vibrator, the support member that supports the vibrator on the other part H is It is characterized by being supported so as not to inhibit rotation around nodes of bending vibration.

[Implementation example] The present invention will be explained below with reference to illustrated embodiments.

FIGS. 1A and 1B are cross-sectional views of an ultrasonic motor showing a first embodiment of the present invention. Vibrator 12 in this motor
is composed of a longitudinal vibrator 4 and a bending vibrator 11,
The bending vibrator 11 is formed by adhering a thin piezoelectric material 6 polarized in the thickness direction to the upper surface of a relatively thick plate-like elastic body 5 having a rectangular planar shape. When a high frequency voltage is applied to the piezoelectric body 6 in its polarization direction, the bending vibrator 1 causes bending vibration, and when a signal of a specific frequency is further applied, it causes a resonance bending standing wave vibration. In the case of this embodiment, the bending vibrator is configured so that first-order bending resonance vibration is most efficiently excited.

On the other hand, the longitudinal vibrator 4 is wider than the bending vibrator 11 (
1(A)), and is located at two nodes of the first-order bending vibration of the bending vibrator 11, and on the opposite side to the side to which the piezoelectric body 6 is attached. The bending vibrator vibrates in the thickness direction of the bending vibrator 1 when a high frequency voltage is applied thereto. Furthermore, a slider 4a made of a wear-resistant friction material is fixed to the tip surface of the vertical vibrator 4.

The slider 4a is pressed into frictional contact with a slide plate 3 made of a wear-resistant friction material fixed to the upper surface of a rail member 2 fixed to a stationary member (not shown).

On the other hand, on the surface of the rail member 2 on the side to which the slide plate 3 is not fixed, linear guide grooves 2a having a semicircular cross section are bored in two places parallel to the direction in which the vibrator 12 is driven. has been done. Further, a part of the rail member 2 and the bending vibrator 1] are disposed within the motor support frame,
This motor support frame 1 is formed of a channel-shaped member having a U-shaped cross section so as to surround a part of the rail member 2 and the bending vibrator 11. This support frame 1 is provided with a straight, parallel ball storage groove 1a having a semicircular cross section similar to the guide groove 2a at a position opposite to the guide groove 2a. Groove 1a and the guide groove 2a
A plurality of bearing balls 13 are arranged in both grooves. As a result, the support frame 1 is configured to be movable only in the direction of the guide groove 2a of the rail member 2 while holding the ball 13 in the ball storage groove la.

The bending vibrator 11 is attached to the support frame 1 in the following manner. That is, the bending vibrator 1
At the position of the bending vibration node 1, four cylindrical shaft-shaped support parts 5a protruding in the width direction of the bending vibrator 11 are integrally provided on the elastic body 5 at symmetrical positions. This protruding support part 5
A support member 14 with a flange is fixed or fitted to the outer periphery of a, and the protruding support part 5a is fitted into the engagement notch 7b of the holder 7 fixed to the support frame 1 with screws 10. As a result, the bending vibrator 11 is attached to the support frame 1.

The holding body 7 is made of a channel-shaped member formed in an inverted U-shape in cross section so as to surround the bending vibrator 11 from above,
The engagement notch 7b is formed in the left and right edges of the engagement notch 7b at a portion facing the protruding support portion 5a. and,
The middle portions of both left and right edges are bent upwards to form attachment pieces 7a that protrude horizontally outward to the left and right in the width direction, and the engaging notches 7b are fitted into the protruding support portions 5a. By placing the double clawed piece 7a of the holder 7 on the upper surface of the support frame 1, and screwing the screw 10 through the mounting piece 7a and onto the upper surface of the support frame 1 via the disc spring 8 and the spacer 9. The holding frame 7 is fixed to the support frame 1. Further, in this attached state, the design is such that there is a slight gap between the attachment piece 7a and the upper surface of the support frame. Therefore, the disc spring 8
By adjusting the elasticity 0 and the screwing amount of the screw 10 using the spacer 9, the pressing force generated by the spring 8 directly applies to the vibrator 12, thereby increasing the pressing force of the slider 4a against the contact surface of the slide plate 3. can be adjusted optimally.

Further, in this embodiment, the support member 14 is made of a soft elastic member such as rubber, urethane, or felt.

According to the ultrasonic motor of the first embodiment configured in this way, the minute rotational vibrations generated on the outer circumference of the protruding support portion 5a are absorbed by the elastic deformation of the support member 14, so that the bending vibration caused by the support is absorbed. The energy loss of the child 11 can be reduced.

Furthermore, since the elastic deformation of the support member 14 is constant and stable, the output of the bending vibrator 11 is also stable. Moreover, vertical oscillator 4
Even if an unbalanced vibration occurs in the combined vibration of the oscillator 12 and the bending oscillator 12, the support member 4 has a vibration-proofing effect, so that unnecessary vibrations will not leak to the outside of the oscillator 12. Therefore, unpleasant audible sounds can be prevented and the motor output 1 is also stable.

In addition to the above-mentioned materials, the support member 14 may be made of other synthetic resin materials as long as they are vibration-proof and have low rigidity, or may be made of inorganic materials such as carbon fiber or glass fiber, and resin materials. The material may be a composite material such as felt, woven fabric/foam material, etc.

Further, this support member 14 may be manufactured as a component and may be glued or press-fitted into the protruding support portion 5a, or may be coated with a material on the protrusion support portion 5a, or may be formed by molding. . In the case of this embodiment, the support member 14 is formed of a cylindrical body with a flange, and the flange portion is configured so that the holding body 7 and the elastic body 5 do not come into direct contact with each other, so that vibrations from the flexural vibrator 1 are prevented. Transducer 1 in the protected state
The lateral position of 2 relative to the holder 7 can also be determined. Furthermore, if the support member 14 is made of an insulating material, the holder 7
Even if it is made of metal, it is possible to easily electrically insulate it from the electrode exposed on the surface of the piezoelectric body 6 to which a high-frequency, high-voltage electrical signal is applied.

Furthermore, since the holder 7 can be easily made by pressing a thin metal plate, the motor can also be made more inexpensively and more compactly.

Further, in the first embodiment, the support member 14 is configured to self-deform to absorb minute rotational reciprocating vibrations around the nodes of the flexural vibrator 1;
This can also be achieved by reducing the friction between the support part 5a and the support part 5a, and by making it movable.

Next, this will be described as a second embodiment of the present invention. In this case, the surface roughness of the engagement notch 7b and the support part 5a that contact the support member 14 are made fine and smooth, and
The support member 14 is also made of a low-friction material with a smooth and fine surface roughness.

Further, the movable contact portion may be provided on either one of the support member 14 and the support portion 5a or the support member 14 and the engagement notch portion 7b, or both may be provided as contact portions.

Looking at the movement of the nodes of vibration of the bending vibrator 11, it is accompanied by a minute rotational movement around the node 3 and a movement in which the interval between the nodes expands and contracts. In the first embodiment, this expansion and contraction movement is also performed by the support member 14.
However, in this second embodiment, a gap is provided between the outer circumferential surface of the support member 14 and the inner circumferential surface of the engagement notch 7b, so that the expansion and contraction movement of the node interval can be absorbed. do. Of course, this gap may also be provided between the inner circumferential surface of the support member 14 and the outer circumferential surface of the support portion 5a.

Further, the position of the vibrator 12 relative to the holder 7 is precisely determined by the centripetal action exerted by the pressing between the outer circumferential surface of the support member 14 and the inner circumferential surface of the engaging notch 7b.

This movable support part is made of a resin material with excellent sliding properties, durability, and vibration-proofing properties, such as PTFE (polytetrafluoroethylene), PP5 (polyphenylene sulfide), etc.
FAI (polyamideimide).

Composite resins made of resins such as PI (polyimide), PE5 (polyether sulfone), and PEEK (polyether ether ketone), or reinforced with GF (glass fiber), CF (carbon fiber), etc. It is preferable to use Support member 1 is made of these resins.
4 may be molded or coated. Further, it may be coated with a dry lubricant such as Teflon or molybdenum disulfide, and furthermore, a bearing using a ball bearing or rollers may be used.

In addition, as another example of the movable support part mentioned in 1., the movable support part is coated with a lubricant such as oil or grease to reduce friction.

High durability may be achieved. Low friction and high durability can be easily achieved by using oil. However, if maintenance is not done, sufficient durability cannot be obtained, and if oil emanates from the support, the support will rapidly wear out and the performance of the motor will be significantly reduced. It is preferable that the support member 14 is made of an oil-impregnated material instead of being attached to the support member 14, so that the above-mentioned problems will not occur. Further, even if the support member 14 is not used, either the support portion 5a or the holder 7 may be made of an oil-impregnated material.

If oil or grease is used in this way, the oil film of the oil or grease has a damping effect, thereby preventing unnecessary vibrations.

FIGS. 2(A) and 2(B) are main part configuration diagrams of an ultrasonic motor showing a third embodiment of the present invention. The configuration of the ultrasonic motor of this third embodiment is the same as that of the ultrasonic motor of the first embodiment except for the mounting structure of the bending transducer 11 to the support frame 1. The main differences from the embodiment will be explained, and the same components will be denoted by the same reference numerals.

First, the main difference is that the support portion 5a is formed of four support portions 5Aa consisting of circular holes drilled in the elastic body 5A, and the engagement notch 7b is integrally formed in the holder 7A. The engaging bent portion 7Ab is constituted by a bent protrusion. The holding body 7A is formed of an inverted U-shaped channel member that covers the bending vibrator 1 from above,
The engaging bent portions 7Ab are formed by bending inward at the lower portions of both left and right edges, and are respectively formed at the lower portions of the four supporting portions S.
Fits into Aa.

And between the four supporting parts 5Aa and the engaging bent part 7Ab, there is a space between the first part 5Aa and the engaging bent part 7Ab. A support section (6) rA' 14A similar to that of the second embodiment is provided. Also, a mounting piece 7A for attaching the holding body 7A to the upper surface of the support frame 1.
In this embodiment, a is bent so as to act as a leaf spring, and has an elastic function that presses the vibrator 12 onto the rail member 2. Further, the slide plate 3 is not attached to the rail member 2. This is because the contact interface between the slider 4a and the rail member 2 should be able to obtain optimal frictional force and wear resistance by selecting the material of the partner. For example, if the rail member 2 is made of SK steel or stainless steel, It is best to use a wear-resistant and non-aggressive resin such as PTFE containing Teflon for the slider 4a. Also,
Of course, the material on the rail member side and the material on the slider side may be reversed.

According to the third embodiment configured in this way, the support portion 5A
a can be easily formed into the elastic body 5A, and
The engaging bent portion 7Ab can also be easily formed integrally with the holder 7, and a spring for press-fitting the vibrator 12 to the rail member 2 is not required. 12 Supports 7 The supporting structure is simplified and costs are reduced. Furthermore, in the case of this embodiment, the length of engagement between the support member 1.4A and the support recess 5Aa can be made longer than in the first embodiment, and the space required for this is also small, so that stable vibration can be achieved in a space-saving manner. This has the effect of being able to support child 12.

FIGS. 3A and 3B show a fourth embodiment of the present invention. The configuration of the ultrasonic motor of this fourth embodiment is also similar to that of the ultrasonic motor of the first embodiment except for the mounting structure of the bending vibrator 11 to the support frame 1.
Only the differences from the first embodiment will be explained.

The difference from the first embodiment is that the support part 5Ba provided on the elastic body 5B is formed with a through hole bored in the width direction of the elastic body 5B, and the retainer SBa is inserted through the support part SBa. An engaging portion is formed at the mating shaft portion 7Bb. The engagement shaft portion 7Bb is composed of a round bar-shaped shaft member with both ends fixed to the open end portions of the left and right side edges of the holder 7B. A support member 14B made of a soft material or a low friction material is provided.

Further, the attachment piece 7Ba of the holder 7B is formed in exactly the same manner as in the first embodiment, and is attached to the support frame 1 in the same manner. Furthermore, no slide plate is used in this embodiment as well.

According to the fourth embodiment configured in this way, the support member 1
Since the engagement length between the support portion 4B and the support portion 5Ba can be longer than that in the third embodiment, the vibrator 12 can be stably supported. Also, considering the case where the pressure bonding force is constant, the supporting member 1-
The contact area between the support member 4B and the support portion 5Ba is the largest, and the contact pressure per unit area that the support member 14B receives is the smallest, so even if a soft material is used for the support member 14B or a low friction material is used Durability is improved.

Note that the support members 14 and 1.4A in each of the above embodiments.

Even if 14B is made of a rigid material, it is designed so as not to hinder the rotation of the joints, so even if the surface of the supporting member is given a mirror finish or lubricated to provide a good sliding surface, the specifications will be improved. The problems of the ultrasonic motor proposed by the applicant (Japanese Patent Application No. 1-195767) mentioned at the beginning of this paper can be solved.

Incidentally, in each of the above embodiments, the rail member was fixed, but the support frame 1. Of course, the holding frame 7 and the vibrator may be fixed and the rail member 2 may be moved.

[Effects of the Invention] As described above, according to the present invention, it is possible to support the oscillator without inhibiting the vibration of the flexural oscillator, which is the driving source of the ultrasonic motor. It is possible to manufacture a highly efficient motor without any problems.

In addition, the simple support structure makes the vibrator stable.
Moreover, since the motor can be supported reliably and the support portion is made of a vibration-absorbing material, the motor can be driven stably. Therefore, it is possible to prevent the generation of unpleasant audible sounds without generating unnecessary vibrations, and to provide an ultrasonic motor that eliminates the problems of this type of motor.

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[Brief explanation of drawings]

1(A) and 1(B) are sectional views of essential parts of an ultrasonic motor showing a first embodiment of the present invention, in which FIG. 1(A) is a vertical sectional view of essential parts, and FIG. ) is a side sectional view taken along the line X-X in FIG. Side view of transducer holding frame FIGS. 3(A) and 3(B) are a longitudinal cross-sectional view of a main part of an ultrasonic motor and a side view of the transducer holding frame, showing a fourth embodiment of the present invention. 1......Support frame 2...
・・・・・・・・・Rail member 4・・・・・・・・・
・・・・・・Longitudinal vibrator 5・・・・・・・・・・・・・・・
・Elastic body 6...Piezoelectric body 11
......Bending vibrator 12...
...... Vibrator 14 ...... Support member 1 547-

Claims (3)

[Claims] (1) A rod-shaped or plate-shaped bending vibrator that excites bending standing wave vibration, and a neutral plane of the bending standing wave vibration that is provided at the node of the standing wave vibration on this bending vibrator. a vibrator consisting of at least one longitudinal vibrator that vibrates in a direction perpendicular to the vertical vibrator; and a rail that is pressed against the tip of the vertical vibrator and is configured to allow relative movement only in a predetermined direction. In the ultrasonic motor that moves the rail and the vibrator relative to each other by a composite vibration of the bending vibration of the bending vibrator and the longitudinal vibration of the longitudinal vibrator, a supporting member that supports the vibrator on another member is provided. An ultrasonic motor characterized in that the ultrasonic motor is supported so as not to inhibit rotation around the bending vibration nodes. (2) The ultrasonic motor according to claim 1, wherein the support member is made of an elastic body. (3) The ultrasonic motor according to claim 1, wherein the support member is made of a low-friction member.