JP2000308375A - Vibrator for ultrasonic motor and ultrasonic motor using the same, and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ultrasonic motor, which is miniaturized and in which the total length of a rod-shaped vibrator is made short without lowering performance. SOLUTION: In this ultrasonic motor, an electromechanical energy conversion element 2 is fixed to an amplitude expansion member 1, which is composed of friction parts 1a, constriction parts 1b and sandwiching and holding parts 1c. The ultrasonic motor is composed of a rod-shaped vibrator 21, which generates a circular motion or an elliptical motion at the friction parts 1a. The ultrasonic motor is composed of a rotating body 5, which comes into pressurization contact with the friction parts 1a at the rod-shaped vibrator 21. In this case, in the ultrasonic motor, the amplitude expansion member 1 at the vibrator 21 is integrally formed of martensitic stainless steel which is quenchd and hardened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibrator for an ultrasonic motor, an ultrasonic motor and an apparatus using the same, and more particularly, to supplying electric energy to an electro-mechanical energy conversion element provided on a rod-shaped vibrator. Accordingly, the present invention relates to a vibrator of an ultrasonic motor that generates a circular or elliptical motion in a friction portion of the rod-shaped vibrator and rotates a rotating body pressed against the friction portion, an ultrasonic motor and an apparatus using the same. . Particularly, the present invention relates to a material of an elastic member constituting the vibrator.

[0002]

2. Description of the Related Art Some ultrasonic motors having a rod-shaped vibrator are known. For example, as shown in FIG.
An ultrasonic motor disclosed in Japanese Patent Application Laid-Open No. H5-211785 is one example. The vibrator of the ultrasonic motor includes a member 101 provided with a constricted portion having an action of expanding vibration displacement. The constricting member uses brass, which is a metal material having relatively low strength. Therefore, in order to enhance the wear resistance, the surface of the member provided with the constricted portion is plated with nickel.

[0003] Further, a female screw portion 1 is provided on an inner diameter portion of the member 101.
01a is cut, and the piezoelectric element 108 is clamped and fixed by the screw 110. At this time, in order to reliably transmit the minute displacement of the piezoelectric element to the member 101, the axial tensile force applied to the screw 110 must be sufficiently large. For this reason, the length of the female screw portion 101a is lengthened to reduce the strength.

Another example is disclosed in Japanese Patent Application Laid-Open No. H8-103088.
In the ultrasonic motor disclosed in the official gazette, as shown in the amplitude enlarging member of FIG. 6, an upper vibrator structure 201 made of brass (corresponding to a member having an action of enlarging the above-described vibration displacement) 201 A sliding member 210-1 made of stainless steel or the like is joined to the sliding member.

[0005] As described above, conventionally, a material having good workability such as brass is used as the material for the vibrator, and the friction portion is usually made of another member.

[0006]

However, in the conventional ultrasonic motor as described above, no consideration is given to the size, particularly to the length, and at present, the ultrasonic motor is downsized. It has been desired.

That is, brass material has been used because it is relatively easy to cut, but the material has relatively low Young's modulus and low strength, which has prevented the bar-shaped ultrasonic motor from being shortened. .

SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional technique, and it is possible to reduce the size of an ultrasonic motor, to reduce the cost without deteriorating the performance, and to shorten the length of the rod-shaped vibrator. It is an object of the present invention to provide a motor vibrator and an ultrasonic motor and a device using the same.

[0009]

That is, according to the present invention, there is provided an electric-power expanding member comprising a friction portion, a constricted portion and a holding portion.
The mechanical energy conversion element is fixed, and is used for an ultrasonic motor including a rod-shaped vibrator that generates a circular or elliptical motion in the friction portion and a rotating body that presses and contacts the friction portion of the rod-shaped vibrator. A vibrator for an ultrasonic motor, characterized in that a vibrating member of the vibrator is integrally formed of martensitic stainless steel hardened by quenching.

When the martensitic stainless steel is quenched and hardened, mechanical properties 5 times higher in tensile strength and 2 times higher in Young's modulus than those of brass material can be obtained.

According to another aspect of the present invention, there is provided a rod-shaped vibrator in which an electromechanical energy conversion element is fixed to an amplitude-enhancing member comprising a friction portion, a constricted portion, and a holding portion, and a circular or elliptical motion is generated in the friction portion. And an ultrasonic motor consisting of a rotating body that comes into pressure contact with a friction portion of the rod-shaped vibrator, wherein the amplitude-enlarging member of the vibrator is integrally formed of martensitic stainless steel hardened by quenching. An ultrasonic motor characterized in that:

Further, the present invention is an apparatus characterized in that the above-mentioned ultrasonic motor is provided as a drive source.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A vibrator for an ultrasonic motor according to the present invention is constructed such that an electromechanical energy conversion element is fastened to a widening member provided with a friction portion, a constricted portion and a holding portion by a fastening member such as a bolt. It is used for an ultrasonic motor composed of a rod-shaped vibrator that is fixed and generates a circular or elliptical motion in the frictional part, and a rotating body that comes into pressure contact with the frictional part of the rod-shaped vibrator. The member is integrally formed of martensitic stainless steel hardened by quenching.

As described above, the present invention provides a friction portion of a vibrator,
By using martensitic stainless steel hardened by quenching for the material of the amplitude-enlarging member consisting of the constricted part and the pinching part, it is about five times as large as that conventionally used for brass amplitude-enlarging member. The elastic limit strength and the Young's modulus were doubled. For this reason, even if the holding portion 1c is thinned to shorten the overall length of the vibrator, a sufficient adhesion force can be secured. Even if the length of the fastening portion such as a screw is reduced to about 1/5, the necessary strength can be secured, so that a sufficient fastening force can be obtained.

On the other hand, in the conventional example, the friction sliding portion of the amplitude expanding member is made of a material having particularly high abrasion resistance. However, if the martensitic stainless steel hardened by quenching in the present invention is used, the friction resistance is kept as it is. It was found that the friction sliding member had a high abrasion property, and a wide material could be manufactured with a single material, so that the manufacturing cost was reduced.

Further, the present invention can be used for various kinds of equipment by using an ultrasonic motor using the above-described vibrator as a drive source. Specific examples of the equipment include optical equipment such as a camera, office equipment such as a printer and a copying machine, and automobile-related equipment such as a power window and an active suspension.

[0017]

EXAMPLES The present invention will be specifically described below with reference to examples.

Example 1 FIG. 1 is a sectional view showing an ultrasonic motor using a vibrator according to a first embodiment of the present invention. In the figure, an ultrasonic motor according to the present invention includes a friction portion 1a, a narrow portion 1b, and a holding portion 1a.
A vibrator 2 composed of an amplitude expanding member 1 in which c is integrally formed, and a piezoelectric element 2 which is an electromechanical energy conversion element
1 and a rotating body 5 in pressure contact with a friction portion 1a of the vibrator 21.

In FIG. 1, two amplitude expansion members 1 are used, and a piezoelectric element 2 which is an electromechanical energy conversion element is used.
And a flexible printed circuit board 12 for supplying power to the piezoelectric element 2 and a support member 3 for supporting these members.
Are clamped and fixed by the hollow bolts 6 to form a rod-shaped vibrator 21. A bearing 7 is press-fitted into the inner diameter portion of the hollow bolt 6 to position the rod-shaped vibrator with respect to the output shaft 10.

The rod-shaped vibrator 21 combines the two bending vibrations by the voltage applied to the piezoelectric element 2 to generate a swinging motion at both ends. Due to the swinging motion, a circular or elliptical motion is generated on the friction sliding surface 1d of the friction portion 1a at both ends. On the other hand, a stainless steel stepped pipe-shaped friction member 4 made by press working is used as an adhesive for the rotating body 5.
They are joined by brazing or welding. The end face of the stepped pipe-shaped friction member is pressed against the friction sliding surface 1 d by a pressure spring 11.

The rotational force of the rotating body 5 is transmitted to the output shaft 10 via the rotation stopper 7a. The reaction force of the pressure spring is received by two E-shaped stop rings 8. Since the E-shaped stop ring 8, the output shaft 10 and the detent 7a are joined by an adhesive, the rotational force of the rotating body 5 is reliably transmitted to the output shaft. Also, instead of using an adhesive, joining may be performed by spot welding or brazing using a laser or the like. The output shaft 10 is supported by two case-side bearings 9. The case is separated into cases 13 and 14, and the support member 3 that supports the entire vibrator is sandwiched and fixed.

FIG. 2 is a schematic diagram showing a vibrator used in the ultrasonic motor of FIG. The amplitude expanding member 1 is functionally divided into three parts. That is, the friction portion 1a, the constricted portion 1b, and the holding portion 1c. The displacement of the electromechanical energy conversion element can be enlarged by the constricted portion 1b and taken out as the displacement of the friction portion. The shape of the constriction,
A desired vibration displacement can be obtained by adjusting the diameter. By the way, there is a screw portion 1e in the inner diameter portion of the amplitude increasing member 1, but not in the inner diameter portion of the constricted portion. The reason is that the constricted portion 1b is the place where the deformation is the largest, so when the screw thread is applied to the inner diameter of the constricted portion, frictional heat is generated at the joint surface between the external thread and the internal thread, resulting in a vibrator with low electric-mechanical energy conversion efficiency. It is because it becomes.

In the present embodiment, a quenched and hardened martensitic stainless steel JIS
SUS440C was used. The amplitude expanding member 1 has a friction portion 1a, a constricted portion 1b, and a holding portion 1c integrally formed, and a friction sliding surface 1d is also made of the stainless steel. Also,
No surface treatment such as plating is applied. As described above, it is possible to reduce the thickness of the holding portion of the amplitude expanding member to about half. As a result, the entire vibrator has become significantly shorter. In addition, although quenching treatment is required, it is not necessary to join a separate friction member to the friction portion, so that the manufacturing cost is eventually reduced.

Further, the following effects were obtained in the present invention. First, the anisotropy in bending stiffness was reduced. The conventional brass has undergone a special manufacturing process for a member having an increased amplitude in order to reduce the anisotropy. Therefore, the material cost is significantly higher than that of a normal brass material. On the other hand, in the quenched martensitic stainless steel, there is no difference in bending rigidity depending on the bending direction. That is, the resonance frequency was almost the same regardless of the bending direction. As a result, when the two bending vibrations are combined, the trajectory of the swinging motion described above becomes almost a perfect circle, the unevenness of the frictional transmission to the rotating body is reduced, and the improvement of the motor efficiency and the reduction of the unevenness of the rotation can be achieved. Was. The quenching of the martensitic stainless steel resulted in delicate martensite in the metal structure, and it is considered that the reason for the above effect was that the uniformity of the material was improved.

Second, reliability is improved because it is not necessary to join a separate friction member. Conventionally, the joining was performed with an epoxy adhesive, but if left in an environment of high temperature and high humidity for a long period of time, the friction member sometimes peeled off. Therefore, there has been a problem that the efficiency of the motor is remarkably reduced. This has the same problem of peeling of plating even in a method using a surface treatment film such as plating as a friction member, but the present invention has eliminated such a problem.

Embodiment 2 FIG. 3 is a schematic view showing another embodiment of the vibrator of the present invention. 4 shows another example of the vibrator portion of the ultrasonic motor according to the first embodiment. Hollow bolt is one side of amplitude expansion member 1-1
It is united with. Since the position of the bolt does not shift in the axial direction at all with respect to the entire vibrator, the balance of vibration is stabilized. That is, since the magnitudes of the vibrations generated in the two amplitude expanding members 1-1 and 1-2 are always equal, there is no difference in the frictional force transmitted to the two rotating bodies. Further, a bearing 7 for supporting the output shaft 10 is provided on the inner diameter portion of the hollow bolt. In this embodiment, since the hollow bolt portion is integral with the amplitude expanding member, the bearing and the vibration The coaxiality with the width-enlarging member is improved, and the pipe-shaped friction member 4 rotates at a substantially perfect center of the amplitude-enlarging member. As a result, the efficiency of the motor was improved, and the wear of the friction sliding portion was reduced.

Embodiment 3 FIG. 4 is a sectional view showing another embodiment of the ultrasonic motor of the present invention. This ultrasonic motor has no output shaft.
Output to the outside is performed via a gear 17. The bolt 15 for sandwiching and fixing the amplitude expanding member 1 and the piezoelectric element 2 has thread portions at both ends. A large nut 16 is provided at one end of the screw portion, and the large-width member 1, the piezoelectric element 2, and the elastic member 20 are integrally held and fixed.

On the other end, there is a small nut 19 for fixing the fixing member 18. The amplitude expanding member has no thread portion, and the small diameter portion 1f is pressed by the flange portion 15a of the bolt 15. That is, the screw portion 1e in the first embodiment.
There is a small-diameter portion 1f instead of. In other words, it is a single thread. Because the whole amplitude expanding member is quenched martensitic stainless steel JIS SUS420j2,
The axial thickness of the small diameter portion was also made thinner than before. Therefore, the overall length of the vibrator was shortened, and the size of the motor was reduced.

As described above, the present invention has made it possible to reduce the cost and size of the ultrasonic motor, and more specifically, to reduce the overall length of the rod-shaped vibrator at low cost without deteriorating the performance.

In the case of using a vibrator in which the electro-mechanical energy conversion element is sandwiched and fixed between the amplitude enlarging members like the ultrasonic motor of the present invention, it is inevitable to shorten the total length of the vibrator. The thickness of the holding portion must also be reduced. On the other hand, since the displacement of the electro-mechanical energy conversion element is very small, if the close contact of the holding portion with the holding surface is not reliable, the displacement will not be properly transmitted to the amplitude increasing member, resulting in a motor with low efficiency. This phenomenon becomes more remarkable as the displacement becomes larger.

By the way, in the rod-shaped vibrator of the present invention, the vicinity of the center of the amplitude expanding member is pulled with a bolt or the like, and the holding surface of the amplitude expanding member is pressed against the electro-mechanical energy conversion element without using an adhesive. If the thickness of the sandwiching portion is small, only the vicinity of the center of the sandwiching surface strongly adheres to the electro-mechanical energy conversion element, and the close contact of the outer peripheral portion becomes uncertain. At this time, when the surface shape of the holding surface was measured, it was found that the surface was plastically deformed. The above phenomenon also occurs in a vibrator that combines a torsion and a longitudinal vibration to generate a circular or elliptical motion in a friction portion.However, particularly in a vibrator that synthesizes a plurality of bending vibrations, the vibration side further increases on the convex side of the bending deformation. Adhesion near the outer periphery of the holding surface tends to be uncertain. Therefore, it is a first problem to increase the adhesion between the electromechanical energy conversion element and the amplitude expanding member to obtain a highly efficient vibrator.

Next, it is necessary to secure the strength of the joint between the fastening member such as a bolt and the amplitude increasing member. The coupling portion is usually a threaded portion, but if the strength is low, the above-mentioned adhesion is not sufficiently obtained, resulting in a transducer having low conversion efficiency. As described above, when the thickness of the width-enlarging member in the axial direction becomes thinner as the size is reduced, the length of the screw becomes shorter, and this tendency becomes remarkable. That is, it is a second problem to obtain a necessary adhesion force without reducing the fastening force and to obtain a highly efficient vibrator.

In order to solve the above-mentioned problem, if brass used as a material of the amplitude expanding member in the conventional example is simply replaced with a high-strength material, the manufacturing cost of the amplitude expanding member generally increases. . That is, a third problem is to provide an inexpensive amplitude increasing member. The present invention relates to the first to third aspects.
Problem was solved.

[0034]

As described above, the present invention relates to an ultrasonic motor using a vibrator in which an amplitude expanding member and an electro-mechanical energy conversion element are sandwiched and fixed, wherein the material of the amplitude expanding member is burned. By using the martensitic stainless steel hardened by the filling treatment, the strength was greatly increased and the overall length was shortened. Therefore, the size of the motor can be reduced. Also, the difference in the rigidity due to the direction of bending has almost disappeared. That is, the anisotropy of the material is reduced, and as a result,
Motor efficiency improved.

Further, since the amplitude expanding member is integrated, the joint of the friction member is eliminated, and the reliability of the motor is improved. The corrosion resistance has also been improved compared to unhardened martensitic stainless steel, and has reached a practical level as a motor. In addition, the quenching reduced the vibration damping rate, resulting in a transducer having high conversion efficiency. Further, the present invention can provide a device using the above-described miniaturized ultrasonic motor.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an ultrasonic motor using a vibrator according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a vibrator used in the ultrasonic motor of FIG.

FIG. 3 is a schematic view showing another embodiment of the vibrator of the present invention.

FIG. 4 is a sectional view showing another embodiment of a rod-shaped ultrasonic motor using the vibrator of the present invention.

FIG. 5 is a sectional view showing a conventional rod-shaped ultrasonic motor.

FIG. 6 is a sectional view showing a conventional amplitude enlarging member.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Amplitude expansion member 1a Friction part 1b Constriction part 1c Nipping part 1d Friction sliding surface 1e Screw part 1f Small diameter part 2 Electromechanical energy conversion element (piezoelectric element) 3 Support member 4 Pipe-like friction member 5 Rotating body 6 Hollow bolt Reference Signs List 7 bearing 7a detent 8 E-shaped stop ring 9 case side bearing 10 output shaft 11 pressure spring 12 flexible printed circuit board 13, 14 case 15 bolt 15a flange 16 large nut 17 gear 18 fixing member 19 small nut 20 elastic member 21 vibration Child 101 Member provided with constricted portion 101a Female screw portion 108 Piezoelectric element 110 Screw

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Claims (3)

[Claims] 1. A rod-shaped vibrator having an electro-mechanical energy conversion element fixed to an amplitude expanding member comprising a friction portion, a constricted portion, and a holding portion, and generating a circular or elliptical motion in the friction portion; A vibrator used for an ultrasonic motor composed of a rotating body that comes into pressure contact with a friction portion of the vibrator,
A vibrator for an ultrasonic motor, wherein a vibration-extending member of the vibrator is integrally formed of martensitic stainless steel hardened by quenching. 2. A rod-shaped vibrator having an electromechanical energy conversion element fixed to an amplitude expanding member comprising a friction portion, a constricted portion, and a holding portion, and generating a circular or elliptical motion in the friction portion; In an ultrasonic motor comprising a rotating body which presses and contacts a friction portion of a vibrator, the amplitude expanding member of the vibrator is integrally formed of martensitic stainless steel hardened by quenching. Ultrasonic motor. 3. An apparatus provided with the ultrasonic motor according to claim 2 as a drive source.