JPH11332262A - Stator for ultrasonic motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively manufacture a stator of an ultrasonic motor by effectively improving the motor performance. SOLUTION: An elastic element 2 of the stator is constituted by dividing a circular elastic member 3 and predetermined number of comb teeth 4 from a circular comb toothed member 5 formed with the teeth 4 at an equal pitch in a circumferential direction. The member 3 is formed in a simple circular state from a metal elastic material, and the member 5 is circularly formed integrally with the teeth 4 by injection molding an injection moldable resin. The member 3 is integrated with the member 5 with an adhesive by adhering or the like. Accordingly, its processing is easy, and its manufacturing cost is largely reduced. A friction heat of the member 5 with a rotor is hardly transferred to piezoelectric ceramics, and the ceramics are hardly affected by the heat, thereby improving the performance of the ultrasonic motor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of a stator for an ultrasonic motor, and more particularly to the technical field of a stator for a traveling wave type ultrasonic motor having a stator having comb teeth.

[0002]

2. Description of the Related Art Conventionally, various ultrasonic motors have been developed, and a traveling wave type ultrasonic motor which is one of the ultrasonic motors operates according to the following principle. That is, as shown in FIG. 5, a traveling wave in which a longitudinal wave and a transverse wave are combined is formed on the surface of the elastic body a serving as the stator S, and this traveling wave propagates in the longitudinal direction W of the elastic body a at the speed of sound. After a predetermined time from the state of the wave 1 indicated by the solid line, the state of the wave 2 indicated by the two-dot chain line is set. Now, focusing on the mass point at the position α on the surface in the state of the wave 1, this mass point moves to the position β on the surface in the state of the wave 2 when the traveling wave enters the state of the wave 2. The motion of the mass point is represented by a lateral amplitude w in the counterclockwise rotation direction in which the mass point is opposite to the traveling direction of the wave.
At the vertical amplitude u, the elliptical motion is in the counterclockwise rotation direction.
In other words, the surface of the elastic body a has the vibration velocity V (= 2πf
u; f performs the elliptical vibration of the frequency of the vibration).
Then, when the rotor R is brought into pressure contact with the surface of the elastic body a performing such elliptical vibration, the rotor R comes into contact with the apex of the elastic body due to the elliptical vibration, and the rotor R and the stator S Of the traveling wave at the vibration speed V in the direction opposite to the traveling wave.

In order to form a traveling wave on the elastic body a of the stator S in such a traveling wave type ultrasonic motor, a bending elastic wave is used. A method for generating this bending elastic wave will be described. As shown in FIG.
Is formed by attaching a piezoelectric body (piezoelectric ceramic) b on which a predetermined number of electrodes are formed by performing a polarization process in a thickness direction such that the polarization directions of adjacent sections are alternately opposite to each other, to an elastic body a. You. In FIG. 6A, the piezoelectric body b
Arrows indicate the polarization direction of each electrode.

When a high-frequency voltage is applied to the piezoelectric ceramic b and the applied frequency is equal to the natural frequency of the stator a, the stator S resonates and causes bending vibration in the circumferential direction as shown in FIG. The vibration wave of this stator S is
If it is divided into nine wavelengths in the circumferential direction as shown in FIG. 7, for example, nine wave peaks m _{1 to} m ₉ are formed, and these waves are so-called standing waves. is there.

On the other hand, as shown in FIG. 6 (b), the phases of the mutual positions of the sections A and B of the piezoelectric ceramic b are shifted by 3/4 wavelength (λ) of the applied high frequency voltage, and the sections A and B are shifted. High-frequency voltage with a temporal phase different from each other by 90 °
The application of a ₀ and .PHI _90, each of the high-frequency voltage .PHI ₀ As described above, the standing wave is generated by .PHI _90, by these standing waves are synthesized cause interference with each other,
For the first time, a traveling wave is formed.

When the stator S is formed in an annular shape and the rotor R is formed in an annular shape having the same diameter, the stator S
The traveling wave based on the elliptical vibration causes the rotor R to rotate due to friction between the stator S and the rotor R. In this case, a sliding material made of resin, which is a friction material, is entirely adhered to a sliding surface of the rotor R (that is, a contact surface with the stator S) so that friction between the stator S and the rotor R is increased. Has been. Thus, the ultrasonic motor is constituted by the annular stator S and the annular rotor R.

[0007]

The stator S
As shown in FIG. 8, the elastic body a of the stator S is used to easily generate the rotational movement of the rotor R due to the above-described elliptical vibration.
On the surface side (the side facing the rotor R), a number of comb teeth c
Are formed. The conventional elastic body a of such a stator S is integrally formed including the comb teeth c by a metal elastic body, and the shape of the comb teeth c is relatively complicated, and a large number of comb teeth c are formed. Therefore, in manufacturing the elastic body a, a manufacturing method of cutting an annular metal elastic body by cutting has to be conventionally used, and the manufacturing cost is high.

Further, frictional heat is generated in the comb teeth c due to friction between the sliding member adhered to the rotor R and the comb teeth c provided in the stator S. However, as described above, the elastic body a is formed integrally from the metal elastic body including the comb teeth c, and the piezoelectric ceramic b is directly bonded to the elastic body a with the adhesive d as shown in FIG. From that
This frictional heat is transmitted to the piezoelectric ceramics b and greatly affects the characteristics of the piezoelectric ceramics b.
In addition, since the performance of the ultrasonic motor is also affected by the effect of the heat on the characteristics of the piezoelectric ceramic b, frictional heat hinders the performance improvement of the ultrasonic motor.

Further, as shown in FIG. 9, the elastic body a of the stator S and the piezoelectric ceramics b are bonded to each other by an adhesive d. For this reason, since the elastic body a prevents the vibration of the piezoelectric ceramics b, even if the comb teeth c are formed, the standing wave due to the bending vibration is hardly generated. As a result, the amplitude of the traveling wave is reduced, so that there is a problem that the performance improvement of the ultrasonic motor is limited.

The present invention has been made in view of such a problem, and an object of the present invention is to provide an ultrasonic motor which can more effectively improve the performance of an ultrasonic motor and can be manufactured at low cost. It is to provide a motor stator.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a stator of an ultrasonic motor according to the present invention is provided with an elastic body having a predetermined number of comb teeth and joined to the elastic body. An ultrasonic motor including at least a stator having a piezoelectric body, wherein the elastic body is joined to the piezoelectric body, and an annular elastic member made of a metal elastic body, and the comb made of an injection-moldable material. It is characterized by being formed by joining an annular comb-shaped member having teeth formed thereon.

According to a second aspect of the present invention, there is provided an ultrasonic motor including at least a stator having an elastic body having a predetermined number of comb teeth and a piezoelectric body joined to the elastic body. A predetermined number of second comb teeth are formed on the side opposite to the comb teeth and joined to the piezoelectric body, and only the tip portions of these second comb teeth are joined to the piezoelectric body. It is characterized by being.

Further, according to a third aspect of the present invention, the piezoelectric body is polarized to a predetermined number of electrodes, and the tip portion of the second comb tooth includes a boundary between adjacent electrodes of the piezoelectric body. It is characterized in that it is joined to a predetermined area.

Further, the invention according to claim 4 is characterized in that the elastic body is:
It is formed by joining an annular elastic member made of a metal elastic body, which is joined to the piezoelectric body, and an annular comb tooth member formed of an injection-moldable material and having the comb teeth formed thereon. It is characterized by:

Further, in the invention according to claim 5, the elastic member and the comb-tooth member are joined by an adhesive, or at least a part of the elastic member is inserted and joined to the comb-tooth member. It is characterized by one of the following. Further, the invention according to claim 6 is characterized in that the injection moldable material is any of resin, aluminum, zinc, and magnesium.

Further, the invention according to claim 7 is characterized in that at least a part of the surface of the comb tooth member is plated to form a plated portion. Further, in the invention according to claim 8, at least a part of the surface of the comb tooth member has
It is a sliding surface on which the rotor slides.

[0017]

In the stator of the ultrasonic motor according to the present invention having the above-described structure, the elastic body is formed of an elastic member made of a metal elastic body and an annular member having comb teeth formed of an injection moldable material. And a comb-shaped member. Thus, the elastic member can be formed in a simple shape, and a comb-shaped member having a comb tooth having a complicated shape can be formed by injection molding. Therefore, even if an injection-moldable material is used, the elastic body of the stator has good elastic characteristics as a whole, and furthermore, the processing of the elastic body becomes easy and the manufacturing cost is greatly reduced.

Further, by using a resin as a material that can be injection-molded, the sliding portion of the elastic body of the stator with the rotor is formed of the resin, so that a resin-made sliding material conventionally bonded to the rotor is used. Becomes unnecessary. Therefore, the cost of the rotor is reduced. Further, since the sliding portion of the elastic body of the stator is formed of resin, not only is it difficult to generate frictional heat due to friction with the rotor, but even if frictional heat is generated, the resin has low thermal conductivity. Therefore, it is difficult for this frictional heat to be conducted toward the piezoelectric body by the resin. As a result, the piezoelectric body is hardly affected by frictional heat, and the performance of the ultrasonic motor is improved.

Further, in the present invention, a predetermined number of comb teeth are provided on the side of the elastic body to which the piezoelectric body is joined, and only the tip portions of these comb teeth are partially joined to the piezoelectric body. Accordingly, the flexibility of the stator is increased, so that the vibration of the piezoelectric body is prevented from being hindered by a part of the elastic body. As a result, the amount of vibration of the piezoelectric body increases, so that the amount of vibration of the stator also increases. As a result, the output of the ultrasonic motor increases.

In particular, by virtue of the fact that the adhesive surface of the elastic body is disposed only in a predetermined area including the boundary between the electrodes adjacent to the piezoelectric body, in other words, only at both ends of the piezoelectric body where the vibration amount is large, the vibration of the piezoelectric body The amount will increase more effectively. Further, since the vibration of the piezoelectric body is facilitated because there is no hindrance by a part of the elastic body, the amplitude of the traveling wave is increased, and the performance of the ultrasonic motor is improved.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view similar to FIG. 8, showing an elastic body in a first embodiment of the stator of the ultrasonic motor according to the present invention. FIG. 2A is a radial direction of the elastic body shown in FIG. FIG.

As shown in FIG. 1, the elastic body 2 of the stator 1 of the ultrasonic motor according to the first embodiment is formed of an annular elastic member 3 having the same outer diameter as the elastic member 3, and A predetermined number of comb teeth 4 are divided from an annular comb tooth member 5 formed at a constant pitch in the circumferential direction.
The annular elastic member 3 is formed in a simple annular shape from a metal elastic body made of, for example, phosphor bronze, SUS, or the like as in the related art. The metal elastic body is not limited to phosphor bronze or SUS, and it goes without saying that another metal elastic body may be used.

Further, the comb teeth member 5 is formed in an annular shape integrally with the comb teeth 4 by injection molding from a resin which can be injection molded. As the resin of the comb-tooth member 5, the same resin as a conventional resin-made sliding member adhered to the rotor can be used. Then, as shown in FIG. 2A, the surface of the elastic member 3 on the side opposite to the comb teeth 4 of the comb tooth member 5 is joined by an adhesive, and the elastic member 3 and the comb tooth member 5 are joined. It is integrated. Although not shown, a piezoelectric ceramic is joined to the other surface of the elastic member 3 in the same manner as in the related art.

The first example of the stator 1 thus constructed
According to the method, the elastic member 3 made of a metal elastic body has a simple shape, and the comb tooth member 5 having the comb teeth 4 having a complicated shape is formed by injection molding. It is easier and production costs are greatly reduced.

Further, since the sliding portion of the stator with the rotor is formed of a resin, a resin sliding material conventionally bonded to the rotor is not required, thereby reducing the cost of the rotor. Will be done.

Further, since the sliding portion of the stator is formed of resin, not only is it difficult to generate frictional heat due to friction with the rotor, but even if frictional heat is generated, the resin has low thermal conductivity. Therefore, this frictional heat is not easily transmitted to the piezoelectric ceramics by the resin. This makes the piezoelectric ceramics less susceptible to frictional heat, and improves the performance of the ultrasonic motor.

In addition, as the material of the comb tooth member 5, other than resin, a metal material which can be injection-molded such as aluminum, zinc, and magnesium can be used. By using such a metal material that can be injection-molded, it is possible to form the comb-tooth member 5 having a complicated shape of the comb-tooth portion at low cost by injection (die-cast) molding.
In such a case, such an injection-moldable metal material does not have such a good elastic property, but the elastic body 2 is divided into an elastic member 3 and a comb-tooth member 5, and both these members 3, 3
By using dissimilar metal materials for the elastic members 2,
Can have good elastic properties as a whole and can be molded at low cost.

Further, instead of joining the elastic member 3 and the comb tooth member 5 with an adhesive, a part of the elastic member 3 is inserted into the comb tooth member 5 when the comb tooth member 5 is formed. And can be integrally molded.

FIG. 2 (b) is a view similar to FIG. 2 (a), showing a second embodiment of the stator according to the present invention. The same components as those in the above-described first example are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the above-described first example, the resin comb teeth 4 are simply joined or inserted to the elastic member 3 made of a metal elastic body. However, in the stator 1 of the second example,
As shown in FIG. 2B, plating is performed on the surface of the resin comb teeth 4 of the stator 1 of the first example and the outer peripheral surface of the elastic member 3 to form a plated portion 6. In this case, the plating portion 6 is formed over the entire surface of the resin comb teeth 4 including the sliding surface with the rotor. According to the stator 1 of the second example, since the sliding surface of the resin-made comb teeth 4 with the rotor is hardened by the plated portion 6, early wear of the resin-made comb teeth 4 is prevented, and the durability of the stator 1 is improved. Is improved. Other configurations and other effects of the second example are the same as those of the stator 1 of the first example.

FIG. 2 (c) is a view similar to FIG. 2 (b), showing a third embodiment of the stator according to the present invention. The same components as in the above-described second example are denoted by the same reference numerals, and a detailed description thereof will be omitted.

In the above-described second example, the plating portion 6 is formed over the entire surface of the resin comb teeth 4 of the stator 1 and the outer peripheral surface of the elastic member 3. The plating part 6 is formed only on the sliding surface of the comb teeth 4 with the rotor. According to the stator 1 of the third example, the plating portion 6 is formed only on the sliding surface of the resin comb teeth 4 with the rotor, so that the plating process is simplified and
Less plating material is required. Other configurations and other effects of the third example are the same as those of the stator 1 of the second example.

FIG. 3 is a view partially showing a fourth embodiment of the stator according to the present invention. The same components as those in the above-described first example are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 3, the elastic body 2 in the stator 1 of the fourth embodiment is formed by integrating the comb teeth 4 from a metal elastic body in the same manner as the conventional elastic body a. A predetermined number of comb teeth 8 having a relatively long pitch are formed on the side to be joined to the ceramics 7. Then, the tooth crests 8 a of the comb teeth 8 are joined to the piezoelectric ceramics 7 by an adhesive 9. In that case, the tip portion 8 of the comb teeth 8
a is joined only to a predetermined region including the boundary 10 between the adjacent piezoelectric ceramics 7,7.

The stator 1 of the fourth example thus constructed
In this case, only the tooth crests 8a of the comb teeth 8 in the elastic body 2 are partially joined to the piezoelectric ceramics 7. Therefore, the flexibility of the elastic body 2 is increased, so that the vibration of the piezoelectric ceramics 7 is prevented from being hindered by a part of the elastic body 2. As a result, the amount of vibration of the piezoelectric ceramics 7 increases, and the amount of vibration of the elastic body 2 also increases. As a result, the output of the ultrasonic motor can be increased.

In particular, in the stator 1 of the fourth example, the bonding surface of the elastic body 2 has a large vibration amount of the piezoelectric ceramics 7 only in a predetermined region including the boundary 10 between the adjacent piezoelectric ceramics 7, 7. Since the piezoelectric ceramics 7 are arranged only at both ends, the vibration amount of the piezoelectric ceramics 7 is more effectively increased.

Further, since the piezoelectric ceramics 7 can be easily vibrated since there is no hindrance by a part of the elastic body 2, the amplitude of the traveling wave can be increased, and the performance of the ultrasonic motor can be improved. .

FIG. 4 is a view similar to FIG. 3, partially showing a fifth embodiment of the stator according to the present invention. The same components as those in the first and fourth examples are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the above-described stator 1 of the fourth example shown in FIG. 3, the elastic body 2 is formed by integrating the comb teeth 4 from a metal elastic body. Is divided into two parts, an elastic member 3 made of a metal elastic body and a resin-made comb tooth member 4 as in the first example shown in FIGS. 1 and 2A. Other configurations are the same as those of the stator 1 of the fourth example.

The fifth example of the stator 1 configured as described above
According to this, the operation and effect of the stator 1 of the fourth example and the operation and effect of the stator 1 of the first example are combined.

In addition, as the material of the resin comb member 4 in the stator 1 of the fifth example, other than the resin, a metal material such as aluminum, zinc, magnesium or the like which can be injection-molded can be used, as described above.

Further, by forming a plating portion 6 as shown in FIGS. 2B and 2C on the resin comb member 4 of the stator 1 of the fifth example, the sliding surface with the rotor is reduced. It can be hard.

[0043]

As is apparent from the above description, according to the stator of the ultrasonic motor of the present invention, the elastic body is made of an elastic member made of a metal elastic body and a comb tooth made of an injection-moldable material. The split configuration with the formed annular comb tooth member allows the elastic member to be formed in a simple shape, and the comb tooth member having a comb tooth having a complicated shape can be easily formed by injection molding. . Therefore, even if a material that can be injection-molded is used for the elastic body of the stator, the elastic properties of the elastic body can be improved, and the processing of the elastic body can be facilitated, and the manufacturing cost can be significantly reduced. .

Further, by using a resin as a material which can be injection-molded and forming a sliding portion of the elastic body with the rotor with the resin, a resin-made sliding material conventionally bonded to the rotor becomes unnecessary. it can. Therefore, the cost of the rotor can be reduced. Further, since the sliding portion of the elastic body of the stator is formed of resin, not only the frictional heat due to the friction with the rotor can be hardly generated, but even if the frictional heat is generated, the frictional heat is applied to the piezoelectric material by the resin. Can be made less likely to be conducted. Thereby, the influence of frictional heat on the piezoelectric body can be prevented, and the performance of the ultrasonic motor can be improved.

Further, according to the present invention, a predetermined number of comb teeth are provided on the side of the elastic body to which the piezoelectric body is joined, and only the tip portions of these comb teeth are partially joined to the piezoelectric body. So
It is possible to prevent the vibration of the piezoelectric body from being hindered by a part of the elastic body. Thus, the amount of vibration of the piezoelectric body and the elastic body can be increased, and as a result, the output of the ultrasonic motor can be increased. In particular, the vibration amount of the piezoelectric body can be more effectively increased by arranging the bonding surfaces of the elastic body only at both ends of the piezoelectric body where the vibration amount is large.

Also, since the piezoelectric body is easily vibrated without being hindered by a part of the elastic body,
The amplitude of the traveling wave can be increased, which can also improve the performance of the ultrasonic motor.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an elastic body in a first example of an embodiment of a stator of an ultrasonic motor according to the present invention.

FIGS. 2A and 2B are partial cross-sectional views of an elastic body of a stator taken along a radial direction. FIG. 2A is a partial cross-sectional view of the first example shown in FIG. 1, and FIG. FIG. 5C is a partial cross-sectional view of an elastic body according to a second example, and FIG.
FIG. 3D is a partial cross-sectional view of an elastic body in an example, and FIG.

FIG. 3 is a diagram partially showing a stator according to a fourth example of the embodiment of the present invention.

FIG. 4 is a diagram partially showing a stator according to a fifth example of an embodiment of the present invention.

FIG. 5 is a diagram illustrating the principle of a traveling wave type ultrasonic motor.

FIG. 6 shows a stator of a general ultrasonic motor,
(A) is a side view, (b) is a plan view.

FIG. 7 is a perspective view showing an excited state of a stator.

FIG. 8 is a perspective view showing an elastic body in a stator of a conventional ultrasonic motor.

FIG. 9 is a view partially showing a conventional stator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Stator, 2 ... Elastic body, 3 ... Elastic member, 4 ... Comb teeth,
5 comb members, 6 plated parts, 7 piezoelectric ceramics,
8 comb teeth, 8a tooth head of comb teeth 8, 9 adhesive, 10
boundary

Claims (8)

[Claims] 1. An ultrasonic motor comprising at least an elastic body having a predetermined number of comb teeth and a stator having a piezoelectric body joined to the elastic body, wherein the elastic body is joined to the piezoelectric body. An annular elastic member made of a metal elastic body and an annular comb tooth member formed of an injection-moldable material and having said comb teeth formed thereon. Stator of sonic motor. 2. An ultrasonic motor, comprising at least an elastic body having a predetermined number of comb teeth and a stator having a piezoelectric body joined to the elastic body, wherein the elastic body has a side opposite to the comb teeth. A predetermined number of second comb teeth are formed on the side to be joined to the piezoelectric body, and only the tip portions of these second comb teeth are joined to the piezoelectric body. Ultrasonic motor stator. 3. The piezoelectric body is polarized into a predetermined number of electrodes, and a tip portion of the second comb tooth is joined to a predetermined area of the piezoelectric body including a boundary between adjacent electrodes. 3. An ultrasonic motor stator according to claim 2, wherein: 4. An annular elastic member formed of a metal elastic body, which is joined to the piezoelectric body, and an annular comb tooth formed of an injection-moldable material and having the comb teeth formed thereon. 4. The ultrasonic motor stator according to claim 2, wherein the stator is formed by joining members. 5. The elastic member and the comb tooth member are joined by an adhesive, or at least a part of the elastic member is inserted and joined to the comb tooth member. The stator for an ultrasonic motor according to claim 1 or 4, wherein: 6. The ultrasonic motor stator according to claim 1, wherein the material that can be injection-molded is any one of resin, aluminum, zinc, and magnesium. 7. The ultrasonic motor according to claim 1, wherein at least a part of the surface of said comb-tooth member is plated to form a plated portion. Stator. 8. The stator for an ultrasonic motor according to claim 7, wherein at least a part of the surface of the comb tooth member is a sliding surface on which a rotor slides.