JP2013135592A - Elastic body for ultrasonic motor and ultrasonic motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an elastic body for an ultrasonic motor that excels in a vibration transmission property regardless of being made of a resin and is also capable of achieving an improvement in a heat resistance property.SOLUTION: An elastic body 3 for an ultrasonic motor, which is fixed to an ultrasonic vibration body 2 for generating ultrasonic vibration through application of a frequency voltage and transmits the ultrasonic vibration generated by the ultrasonic vibration body 2 to a moving body 5 as a surface progressive wave to thereby drive the moving body 5, is made of a thermoplastic resin that has a glass transition temperature of 90°C or higher, is fixed so that both surfaces of the elastic body formed in a plate shape is sandwiched between plate-shaped piezoelectric elements, is caused to vibrate at a resonance frequency through application of a frequency voltage to the piezoelectric elements, has the maximum vibration velocity of 500 mm/sec or higher at the time of increase of the voltage.

Description

  The present invention relates to an elastic body for an ultrasonic motor using ultrasonic vibration by an ultrasonic vibration body such as a piezoelectric element, and an ultrasonic motor including the elastic body.

  Ultrasonic motors that utilize ultrasonic vibrations from piezoelectric vibrators (electromechanical transducers), such as piezoelectric motors, require no windings and are simple in structure, and respond at low speed and high torque. Since it is excellent in controllability and controllability and can be driven minutely and precisely, it is widely used in optical equipment devices such as cameras and DVDs. There are a linear type and a rotor type in the ultrasonic motor, and the ultrasonic vibration from the vibrating body is converted into a linear motion or a rotational motion.

  FIG. 1 is a schematic side view of a rotor type ultrasonic motor, and FIG. 2 is a schematic perspective view of an elastic body constituting the rotor type ultrasonic motor of FIG. The ultrasonic motor 1 is regularly formed on the disk-shaped (or ring-shaped) piezoelectric element 2 having the same outer diameter as the outer diameter of the piezoelectric element 2 and along the outer periphery. A stator 4 to which a ring-shaped elastic body (comb-shaped elastic body) 3 having a comb-shaped convex portion (comb-toothed portion) 3a is fixed; A disk-shaped (or ring-shaped) rotor (rotating body) 5 having the same outer diameter as that of the elastic body is provided. In the ultrasonic motor 1, the stator 4 composed of the piezoelectric element (piezo element) 2 and the comb-like elastic body 3 is a fixed member, whereas the rotor 5 is rotatably arranged. The ultrasonic vibration generated by the piezoelectric element 2 is converted into the rotational motion of the rotor 5 via the comb-like elastic body 3. Specifically, the piezoelectric element 2 is formed of a piezoelectric ceramic that generates distortion when a voltage is applied. When a frequency voltage is applied, the piezoelectric element 2 regularly repeats distortion and recovery (stretching motion), thereby ultrasonic vibration. To do. On the other hand, in the comb-like elastic body 3 fixed to the piezoelectric element, the surface traveling wave (longitudinal wave and transverse wave) transmitted along the surface of the elastic body is combined with the ultrasonic vibration from the piezoelectric element. Rayleigh wave). As a result, an elliptical motion occurs on the surface of the elastic body, and the rotor 5 in pressure contact with the elastic body rotates.

  As the elastic body, a metal material is used because it can generate a surface traveling wave without absorbing ultrasonic vibration from the piezoelectric element. However, elastic bodies made of metal have a high specific gravity and are hard, so their own vibration is low, their formability is low, and in complex shapes such as comb teeth, productivity decreases, rust There are also drawbacks, such as deterioration due to corrosion, difficulty in improving the characteristics by blending additives, etc., and inability to ensure insulation. In addition, although not put into practical use as an elastic body other than metal, an elastic body formed of plastic has been proposed.

  Japanese Patent Laid-Open No. 5-300764 (Patent Document 1) discloses a moving body that contacts an elastic body by applying elliptical motion generated in an elastic body that applies a frequency voltage to the electromechanical conversion element and is joined to the electromechanical conversion element. A drive mechanism is disclosed in which a side of the elastic body that contacts the moving body is formed of resin. In this document, an elastic body made of metal is further interposed between an elastic body made of resin and the electromechanical conversion element.

  However, even in this drive mechanism, since the elastic body contains metal, the vibration is not sufficient and rust is also generated. Further, this document does not describe details of the resin, and the resin usually absorbs ultrasonic vibration as compared with a metal material, and therefore has low vibration transmission. Furthermore, since the elastic body is a friction drive type that is brought into contact with the moving body, frictional heat is generated and heat resistance is required. However, the resin material has lower heat resistance than the metal material.

  Japanese Examined Patent Publication No. 7-89746 (Patent Document 2) discloses a stator composed of a piezoelectric element and an elastic body excited by the piezoelectric element, and a surface of ultrasonic vibration generated in the stator in pressure contact with the stator. In a surface wave motor comprising a mover that is an elastic body that moves on the surface of the stator by a traveling wave, at least one of the two elastic bodies is formed of a synthetic resin material. There is disclosed a surface wave motor in which a vibrating portion having a surface to which the elastic body is pressed, a supporting portion extending from the vibrating portion, and a held portion provided on the outer periphery of the supporting portion are integrally molded. Yes.

  However, even in this document, the synthetic resin material includes engineering plastic, and a material having a low elastic modulus is preferable. An elastic modulus of about 1/10 for a piezoelectric element and an elastic modulus of about 1/20 for a metal. However, details of the synthetic resin are not described.

  Japanese Patent Laid-Open No. 2006-311794 (Patent Document 3) includes an electromechanical transducer that expands and contracts when a voltage is applied, and a movable body that is slidably supported and coupled to the electromechanical transducer. And a movable body support member that is displaced together with the electromechanical conversion element. The drive device moves the movable body along the movable body support member by expansion and contraction of the electromechanical conversion element. A drive device is disclosed in which the material is a fiber reinforced resin composite, and the synthetic resin material constituting the fiber reinforced resin composite is a liquid crystal polymer or polyphenylene sulfide.

  However, since the liquid crystal polymer has low vibration transmission, it is difficult to drive the moving body. On the other hand, polyphenylene sulfide is excellent in vibration transmission, but has low heat resistance and impact resistance, and also has low wear resistance at high temperatures. Furthermore, since polyphenylene sulfide generates sulfides at the time of molding, equipment using a special steel material having anti-sulfurity is also required, resulting in high running costs and low productivity.

JP-A-5-300764 (Claim 1, FIGS. 1 and 3) Japanese Patent Publication No. 7-89746 (Claim 1, page 2, column 4, lines 19-21) JP 2006-311794 A (Claim 1)

  Therefore, an object of the present invention is to provide an elastic body for an ultrasonic motor that is excellent in vibration transmission and can be improved in heat resistance despite being formed of a resin, and an ultrasonic motor including the elastic body. There is.

  Another object of the present invention is to provide an elastic body for an ultrasonic motor that can improve impact resistance and wear resistance at high temperatures and has high productivity, and an ultrasonic motor including the elastic body.

  Still another object of the present invention is to provide an ultrasonic motor elastic body that can improve moldability and property improvement properties and can also provide insulation, and an ultrasonic motor including this elastic body.

  As a result of intensive studies to achieve the above-mentioned problems, the inventors have formed an elastic body of an ultrasonic motor with a thermoplastic resin having a glass transition temperature of 90 ° C. or higher and a specific vibration speed. In spite of being formed of a resin, the present inventors have found that it is excellent in vibration transmission and can also improve heat resistance, thereby completing the present invention.

That is, the elastic body for an ultrasonic motor of the present invention is fixed to an ultrasonic vibration body for generating ultrasonic vibration by applying a frequency voltage, and the ultrasonic vibration generated by the ultrasonic vibration body is moved as a surface traveling wave. An ultrasonic motor elastic body for transmitting to a body and driving the movable body, having a glass transition temperature of 90 ° C. or higher, and sandwiching both sides of the elastic body formed into a plate shape with plate-shaped piezoelectric elements The piezoelectric element is made of a thermoplastic resin having a maximum vibration speed of 500 mm / second or more when the piezoelectric element is loaded with a frequency voltage and vibrated at a resonance frequency to raise the voltage. The thermoplastic resin may be a non-liquid crystal polymer. The thermoplastic resin may be at least one selected from the group consisting of a polyaryl ketone resin, a polybenzimidazole resin, a polyamideimide resin, and an aromatic polyamide resin (particularly, a polyether ether ketone resin). The elastic body of the present invention may be formed of a thermoplastic resin having an Izod impact strength (notched) of 50 J / m or more in accordance with ASTM D256. The elastic body of the present invention may have a tensile elastic modulus based on ISO 527-1 / -2 of about 10 to 30 GPa. The elastic body of the present invention may have a shape having comb teeth. The elastic body of the present invention may further contain an inorganic filler. The inorganic filler may be an inorganic fiber. The proportion of the inorganic filler may be about 20 to 60 parts by weight with respect to 100 parts by weight of the thermoplastic resin. The elastic body of the present invention may be formed of a thermoplastic resin having a density of 3 g / cm ³ or less. In the elastic body of the present invention, the ultrasonic vibrating body may be a piezoelectric element, and the moving body may be a rotating body.

  The present invention also includes an ultrasonic motor provided with the elastic body.

  In the present invention, since the elastic body of the ultrasonic motor is formed of a thermoplastic resin having a glass transition temperature of 90 ° C. or higher and a specific vibration speed, Excellent vibration transmission and heat resistance. In addition, heat resistance, impact resistance, and wear resistance at high temperatures can be improved, and productivity is high. Therefore, the driving performance of the ultrasonic motor is excellent. Furthermore, the moldability and the improvement of characteristics can be improved, and the insulating property can be imparted.

FIG. 1 is a schematic side view of a rotor type ultrasonic motor. FIG. 2 is a schematic perspective view of an elastic body constituting the rotor type ultrasonic motor of FIG. FIG. 3 is a schematic diagram for explaining a measurement method or an evaluation method of the vibration speed of the elastic body and the driving force of the moving body in the embodiment.

[Elastic body for ultrasonic motor]
The elastic body for an ultrasonic motor of the present invention is formed of a thermoplastic resin having high heat resistance and excellent vibration transmission.

  Specifically, the glass transition temperature (Tg) of the thermoplastic resin is 90 ° C. or higher, preferably 90 to 450 ° C., more preferably about 95 to 430 ° C. (particularly 100 to 400 ° C.). From this point, it is preferably 90 to 300 ° C, more preferably about 100 to 200 ° C (particularly 120 to 160 ° C). When the ultrasonic motor is driven, the temperature of the elastic body increases due to heat generation due to vibration, an increase in ambient temperature, heat storage due to friction, and the like, and vibration characteristics decrease. Further, the coefficient of friction of the elastic body also decreases, and the vibration transmission to the moving body decreases. However, when the glass transition temperature is less than 90 ° C., such a decrease in vibration transmission becomes significant. Furthermore, if the glass transition temperature is less than 90 ° C., the wear resistance at high temperatures also decreases, and wear and breakage are likely to occur in a high temperature state (for example, about 90 to 150 ° C.) due to frictional heat. On the other hand, if the glass transition temperature is too high, the elastic modulus is too large, impact resistance and the like are reduced, the glass tends to break, and the durability tends to decrease. The thermoplastic resin used in the present invention has an excellent elastic property by having an appropriate elastic modulus, and in particular, in the case of a comb-like elastic body, the vibration property at the tip portion in contact with the moving body is large. Therefore, the drive transmission force can be improved.

  In this specification, the glass transition temperature can be measured according to the DSC method of ASTM 3418.

  Thermoplastic resins need to have excellent vibration transmission properties. Specifically, both sides of a plate-shaped elastic body are fixed by sandwiching them between plate-shaped piezoelectric elements, and a resonant voltage is applied by applying a frequency voltage to the piezoelectric elements. When the voltage is increased, the maximum vibration speed is 500 mm / second or more, preferably 500 to 1500 mm / second (for example, 600 to 1000 mm / second), more preferably 650 to 900 mm / second (particularly 700). ˜800 mm / second). When the vibration speed is less than 500 mm / second, the transmission of vibration to the moving body is low, and it becomes difficult to drive the moving body. The details of the method for measuring the vibration speed can be measured by the method described in Examples described later.

  The thermoplastic resin preferably has excellent impact resistance, and may have an Izod impact strength (notched) of 20 J / m or more in accordance with ASTM D256, for example, 25 to 200 J / m, preferably 30 to 150 J / m, more preferably about 35 to 100 J / m (particularly 40 to 100 J / m). From the viewpoint of excellent durability, 50 J / m or more is particularly preferable, for example, 50 to 150 J / m, Preferably it is 60-120 J / m, More preferably, it is about 70-100 J / m (especially 75-90 J / m). If the impact strength is too low, the impact strength is weak, vibration is likely to occur, and the durability is lowered. By blending fillers such as glass fiber and carbon fiber, a decrease in linear expansion coefficient and an improvement in rigidity can be expected, but in the case of fine parts, because the impact strength in practice cannot be guaranteed due to the presence or orientation of the fiber, etc. The impact strength of the single resin is preferably within the above range.

The density (specific gravity) of the thermoplastic resin may be, for example, 3 g / cm ³ or less, preferably 0.8 to 2.5 g / cm ³ , more preferably 0.9 to 2 g / cm ³ (particularly 1 ˜1.5 g / cm ³ ). If the density is too large, the vibration property is lowered, and the drive transmission property of the moving body is lowered. The density can be measured by a method based on ISO 1183.

  The thermoplastic resin is not particularly limited as long as it satisfies the above characteristics, but is preferably a non-liquid crystal polymer from the viewpoint of suppressing attenuation and loss of vibration energy. Specific examples include, for example, polyaryl ketone resins. , Polybenzimidazole resin, polyamideimide resin, aromatic polyamide resin and the like. These thermoplastic resins can be used alone or in combination of two or more.

(Polyaryl ketone resin)
The polyaryl ketone resin is an aromatic polyether ketone in which aromatic rings are bonded by an ether bond and a ketone bond. Depending on the ratio of the ether bond to the ketone bond, the polyether ketone resin, the polyether ether ketone resin, It is classified as an ether ketone ketone resin. These polyaryl ketone resins can be used alone or in combination of two or more. Of these polyaryl ketone resins, polyether ether ketone resins having a high proportion of ether bonds are preferred from the viewpoint of excellent mechanical properties such as impact resistance.

Polyetheretherketone-based resins are polyetheretherketone obtained by polycondensation of dihalogenobenzophenone and hydroquinone, and are commercially available under the trade name “PEEK” series from VICTREX and “VESTAKEEP” series from EVONIK However, the polyether ether ketone in which the benzene ring has a substituent (for example, a C _1-3 alkyl group), the polyether ether ketone in which the benzene ring is another aromatic ring such as a naphthalene ring, and the like may be used.

(Polybenzimidazole resin)
In addition to polybenzimidazole, the polybenzimidazole-based resin may have part or all of the benzene skeleton substituted with other aromatic rings (for example, biphenyl ring, naphthalene ring, etc.). In addition, a copolymer unit such as an arylene group such as phenylene may be contained. These polybenzimidazole resins can be used alone or in combination of two or more. Of these polybenzimidazole resins, polybenzimidazole is widely used.

(Polyamideimide resin)
The polyamide-imide resin is a polymer having an imide bond and an amide bond in the main chain, and a polyamide-imide obtained by reacting a tricarboxylic acid anhydride and a polyvalent isocyanate, or a imide obtained by reacting a tricarboxylic acid anhydride and a polyvalent amine. It may be a polyamide imide that has been amidated by reacting with a polyvalent isocyanate after forming a bond. As the tricarboxylic acid anhydride, trimellitic acid anhydride is usually used. Examples of the polyvalent amine and polyvalent isocyanate include polyvalent amines including aromatic amines (phenylenediamine, naphthalenediamine, 2,2-bis (aminophenyl) propane, 4,4′-diaminodiphenyl ether, etc.), aromatic isocyanates ( Polyisocyanates including phenylene diisocyanate, xylylene diisocyanate, tolylene diisocyanate, etc.) are preferred. As the polyamideimide, for example, a polyamideimide described in JP-A-59-135126 may be used.

(Aromatic polyamide resin)
The aromatic polyamide resin may be a polyamide resin containing an aromatic ring, and examples thereof include a polyamide obtained by polymerizing an aliphatic diamine and an aromatic dicarboxylic acid, and a polyamide obtained by polymerizing an aromatic diamine and an aliphatic dicarboxylic acid. It is done. Examples of the aliphatic diamine include alkylene diamines such as ethylene diamine, hexamethylene diamine, and nonamethylene diamine. Examples of the aromatic diamine include phenylenediamine, metaxylylenediamine, naphthalenediamine, and the like. Examples of the aliphatic dicarboxylic acid include succinic acid, adipic acid, sebacic acid, and the like. Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, and phthalic anhydride. Of these aromatic polyamide resins, polyamides obtained by polymerizing C _6-12 alkylenediamines such as hexamethylenediamine and nonamethylenediamine and aromatic dicarboxylic acids such as terephthalic acid are preferred.

(Characteristics of polyaryl ketone resin)
Of these thermoplastic resins, polyaryl ketone resins are preferred, and polyether ether ketone resins are particularly preferred from the viewpoint of excellent balance of vibration transmission, heat resistance and durability.

  The weight average molecular weight of the polyaryl ketone resin (especially polyether ether ketone resin) is, for example, 5000 to 30000, preferably 6000 to 25000, and more preferably about 8000 to 20000 in GPC (polystyrene conversion).

Polyaryl ketone resin (especially a polyether ether ketone resin) volume flow rate (MVR) is in compliance with ISO 1133 (380 ℃ / 5kg) , for example, 10 to 200 cm ^3/10 min, preferably 30~150cm ^3/10 min, more preferably about 50 to 100 cm ^3/10 min.

  Polyaryl ketone resins (especially polyether ether ketone resins) are capable of improving vibration transmission in a tensile test (50 mm / min) based on ISO 527-1 / -2. The elongation and tensile elastic modulus may be in the following ranges.

  That is, the tensile strength may be, for example, about 10 to 300 MPa, preferably about 50 to 200 MPa, and more preferably about 80 to 150 MPa.

  The elongation may be, for example, about 1 to 10%, preferably 2 to 8%, more preferably about 3 to 6%.

  The breaking elongation may be, for example, 10% or more, for example, 10 to 100%, preferably 15 to 50%, and more preferably about 20 to 40%.

  The tensile elastic modulus may be, for example, about 1000 to 10,000 MPa, preferably about 2000 to 5000 MPa, and more preferably about 3000 to 4000 MPa.

(Additive)
Since the elastic body of the present invention is formed of a thermoplastic resin, it can be easily improved in mechanical properties, design properties, and the like by adding an additive for resin.

  For example, the elastic body of the present invention may contain a filler in order to improve mechanical properties such as dimensional stability and rigidity, heat resistance and vibration properties. Examples of the filler include fibrous fillers [for example, inorganic fibers (glass fiber, carbon fiber, glass fiber, asbestos fiber, silica fiber, silica / alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber) , Potassium titanate fiber, stainless steel fiber, aluminum fiber, titanium fiber, copper fiber, brass fiber, etc.), organic fiber (such as high melting point organic fiber such as aramid fiber, fluororesin fiber, acrylic fiber, etc.)], granular filler [For example, carbon black, silica, quartz powder, glass beads, glass powder, silicate (calcium silicate, aluminum silicate, kaolin, talc, clay, diatomaceous earth, wollastonite, etc.), metal oxide (iron oxide, titanium oxide, Zinc oxide, alumina, etc.), metal carbonates (calcium carbonate, magnesium carbonate, etc.), sulfur Salts (calcium sulfate, barium sulfate), silicon carbide, silicon nitride, boron nitride, various metal powders, etc.] and the like. These fillers can be used alone or in combination of two or more.

  Among these fillers, inorganic fillers, particularly fibrous inorganic fillers are preferable, and inorganic fibers such as carbon fibers and glass fibers are widely used. The surface of the inorganic filler may be surface-treated with a surface treatment agent having a functional group (for example, an epoxy compound, an isocyanate compound, a coupling agent, etc.).

  The proportion of the filler is, for example, about 5 to 100 parts by weight, preferably 10 to 80 parts by weight, more preferably 20 to 60 parts by weight (particularly 30 to 50 parts by weight) with respect to 100 parts by weight of the thermoplastic resin. is there. When the proportion of the filler is too large, impact resistance and durability are lowered.

  Furthermore, the elastic body of the present invention includes other additives for conventional resins such as colorants (dye pigments), lubricants, stabilizers (antioxidants, ultraviolet absorbers, heat stabilizers, light resistance stable). Agents), antistatic agents, flame retardants, flame retardant aids, anti-blocking agents and the like.

(Characteristics and manufacturing method of elastic body)
The elastic body of the present invention can be selected from a range where the tensile modulus is, for example, about 1 to 50 GPa in a tensile test (50 mm / min) based on ISO 527-1 / -2, for example, 2 to 40 GPa, preferably Is about 3 to 30 GPa, more preferably about 3.5 to 25 GPa. From the viewpoint of improving vibration transmission, for example, 5 to 50 GPa, preferably 10 to 40 GPa, more preferably 15 to 30 GPa (particularly 20 to 25 GPa). It may be a degree. If the tensile elastic modulus is too small, the vibration transmission property is lowered, and if the tensile elastic modulus is too large, the molding process becomes difficult. Furthermore, it is preferable to adjust the tensile elastic modulus of the elastic body by combining a thermoplastic resin and a filler. By combining the thermoplastic resin and the filler and adjusting the elastic modulus within the above range (especially about 10 to 30 GPa), the mechanical properties such as the dimensional stability and rigidity of the elastic body can be improved and the vibration transmission property can be improved. Can be improved.

  The shape of the elastic body of the present invention can be selected according to the type of the ultrasonic motor. In the case of a linear ultrasonic motor, for example, a two-dimensional shape such as a plate shape (square flat plate shape, disk shape, etc.), a rod shape, etc. In the case of a rotor-type ultrasonic motor, minute projections are regularly formed on the surface in the two-dimensional shape and the three-dimensional shape. The shape (shape which has a comb-tooth part) is preferable. Examples of the planar shape of the convex portion (comb portion) include a quadrangular shape (square shape, rectangular shape, etc.), a triangular shape, and a wave shape. Of these shapes, a quadrangular shape and a corrugated shape are preferable, and a rectangular shape such as a rectangular shape is particularly preferable. The cross-sectional shape of the convex portion (comb portion) is not particularly limited, but is usually a quadrangular shape such as a rectangular shape.

  The shape having the comb-tooth portion is not particularly limited as long as the minute convex portions are regularly formed on the surface, but in the case of a rotor type ultrasonic motor, it is usually a ring shape or a disc shape having the comb-tooth portion. It is. The comb-teeth portion only needs to be formed at the contact portion with the moving body. In the case of a ring-shaped elastic body, it is formed at the opening end, and in the case of a disk-shaped elastic body, it is formed on the surface along the circumference. It may be. Since the elastic body of the present invention is excellent in moldability, even a shape having a comb tooth portion can be manufactured with high productivity, and the vibration property at a comb-shaped minute convex portion is excellent. Driveability can be improved.

  In the shape having a comb tooth portion, when the convex portion (comb tooth portion) has a quadrangular shape such as a rectangular shape and a slit portion is formed between the convex portions, the width of the convex portion is, for example, 0.1 to 30 mm, preferably 0.2 to 15 mm, more preferably about 0.5 to 10 mm, and the height of the convex portion is, for example, 0.1 to 30 mm, preferably 0.2 to 15 mm, and more preferably 0. It may be about 5 to 10 mm. The depth of the slit may be, for example, about 0.1 to 30 mm, preferably about 0.2 to 15 mm, and more preferably about 0.5 to 10 mm. Furthermore, the ratio of the width of the convex portion to the width of the slit portion (the width of the convex portion / the width of the slit portion) is, for example, 0.01 to 100, preferably 0.1 to 10, and more preferably 0.3 to. About 30.

  The elastic body of the present invention can be produced by a conventional molding method, for example, extrusion molding, injection molding, compression molding, or the like, depending on the type and shape of the ultrasonic motor. Of these molding methods, extrusion molding, injection molding, and the like are widely used, and in the case of a three-dimensional shape such as a comb tooth shape, the molding can usually be performed by injection molding.

[Ultrasonic motor]
The ultrasonic motor of the present invention is only required to include the elastic body, and the elastic body is normally fixed to an ultrasonic vibration body for generating ultrasonic vibration by applying a frequency voltage, and the ultrasonic wave The elastic body has a structure that can transmit ultrasonic vibrations from the vibrating body as surface traveling waves to the moving body.

The ultrasonic vibrator is not particularly limited as long as ultrasonic vibration can be generated, but is usually a piezoelectric element. As a piezoelectric material constituting the piezoelectric element, piezoelectric ceramics widely used in an ultrasonic motor, for example, ABO ₃ type such as lead zirconate titanate (PZT), lead lanthanum zirconate titanate, lead titanate, barium titanate, etc. Perovskite oxide can be used.

  As the moving body, a conventional rotor (rotating body) or slider can be used according to the type of the ultrasonic motor, but a rotating body used for the rotor type ultrasonic motor is preferable. The material of the moving body is not particularly limited and can be formed of a conventional metal material or resin, and is usually formed of a metal such as stainless steel, aluminum, or brass. A film made of silicone or fluororesin may be formed on the surface of the moving body in order to improve slidability with the elastic body.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. The abbreviations of the components of the materials used in the examples and comparative examples are as follows, and the elastic bodies obtained in the examples and comparative examples were evaluated by the following methods.

[Glass transition temperature Tg]
Measured according to the ASTM 3418 DSC method.

[Elastic modulus]
The tensile modulus was measured based on a tensile test (50 mm / min) based on ISO 527-1 / -2.

[Vibration speed and driving force of moving body]
A method for measuring or evaluating the vibration speed of the elastic body and the driving force of the moving body will be described below with reference to FIG.

  For the thermoplastic resins of Examples 1 to 5 and Comparative Examples 1 and 2, a 10 cm square, 3 mm thick flat plate mold was injection molded, and the resulting molded body was cut into 1 cm × 3 cm by cutting to obtain a resin. An elastic body 11 was obtained.

  As shown in FIG. 3, the obtained resin elastic body 11 is sandwiched between two plate-like piezoelectric elements 12 (“C-123” manufactured by Fuji Ceramics Co., Ltd., 1 cm × 2 cm × 1 mm), and an adhesive (Huntsman Advanced Materials Co., Ltd. “Araldite”), cured for 24 hours and cured.

  A copper wire 13 is soldered to the electrode of the piezoelectric element 12 to vibrate at the resonance frequency. Vibration is measured with a laser Doppler meter at the maximum speed of vibration. When the voltage is increased, an increase in the vibration speed is observed, but at or above a specific voltage corresponding to the mechanical properties of the resin elastic body, a stagnation or decrease in the vibration speed is observed, but the maximum speed is the vibration speed. .

Further, as shown in FIG. 3, a rotatable disc-like rotating body 14 is pressed against one side surface of the elastic resin body 11 that vibrates at the maximum speed with a pressure of 1 kg / cm ² . The presence or absence of rotation was evaluated.

[Impact strength]
Measured according to ASTM D256 (notched).

[Abrasion resistance]
In accordance with JIS K 7128-1986, using a Suzuki friction friction tester with a furnace, the counterpart material was SUS304, and the dynamic friction coefficient was measured when sliding at a temperature of 100 ° C. for 7 hours. The evaluation of the test piece that could not be measured by fracture was “buckling”.

[Abbreviations for materials]
CF-containing PEEK: Polyetheretherketone containing 30% by weight of carbon fiber, “VESTAPEEK4000CF3” manufactured by Daicel-Evonik Co., Ltd., density 1.41 g / cm ³
PEEK: Polyetheretherketone, “VESTAPEEK4000” manufactured by Daicel Evonik Co., Ltd., density 1.30 g / cm ³
PBI: Polybenzimidazole, “Polypenco PBI” manufactured by Quadrant Polypenco Japan, density 1.30 g / cm ³
PAI: Polyamideimide, “Torlon T4000” manufactured by Solvay Advanced Polymers Co., Ltd., density 1.14 g / cm ³
PA9T: Aromatic polyamide, “Genesta N1000A” manufactured by Kuraray Co., Ltd., density 1.42 g / cm ³
PPS: polyphenylene sulfide, “Torelina A400” manufactured by Toray Industries, Inc., density 1.35 g / cm ³
PC: Polycarbonate, “Caliber 301-10” manufactured by Sumitomo Dow Co., Ltd., density 1.20 g / cm ³
Epoxy glass: uncolored epoxy glass laminate, manufactured by Nikko Kasei Co., Ltd., conforming to NEMA standard G10, density 1.20 g / cm ³
Acrylic: Acrylic resin, “Acrypet MD” manufactured by Mitsubishi Rayon Co., Ltd., density 1.47 g / cm ³ .

Example 1
An elastic body was obtained by injection molding (injection molding pressure: 250 MPa, molding temperature: 400 ° C., mold temperature: 200 ° C.) using CF-containing PEEK.

Example 2
An elastic body was obtained by injection molding (injection molding pressure: 250 MPa, molding temperature: 390 ° C., mold temperature: 200 ° C.) using PEEK.

Example 3
A commercially available PBI molded body (“Polypenco PBI” manufactured by Quadland Polypenco Japan Co., Ltd.) was cut to obtain an elastic body.

Example 4
Using PAI, an elastic body was obtained by injection molding (injection molding pressure: 200 MPa, molding temperature: 350 ° C., mold temperature: 200 ° C.).

Example 5
Using PA9T, an elastic body was obtained by injection molding (injection molding pressure: 220 MPa, molding temperature: 330 ° C., mold temperature: 180 ° C.).

Comparative Example 1
An elastic body was obtained by injection molding (injection molding pressure: 60 MPa, molding temperature: 310 ° C., mold temperature: 150 ° C.) using PPS. In addition, sulfide was generated during molding.

Comparative Example 2
An elastic body was obtained by injection molding (injection molding pressure: 120 MPa, molding temperature: 330 ° C., mold temperature: 80 ° C.) using PC.

Comparative Example 3
As an elastic body, glass epoxy was used instead of the injection molded body.

Comparative Example 4
An elastic body was obtained by injection molding (injection molding pressure: 100 MPa, molding temperature: 220 ° C., mold temperature: 60 ° C.) using acrylic.

  The evaluation results of the elastic bodies obtained in the examples and comparative examples are shown in Table 1.

  As is apparent from the results in Table 1, the elastic bodies obtained in the examples are excellent in driving performance, heat resistance and impact resistance. In particular, the elastic bodies of Examples 1 and 2 (particularly the elastic body of Example 1) are excellent in the balance of these characteristics.

  On the other hand, the elastic body obtained in Comparative Example 1 has low heat resistance and impact resistance and also low productivity. Furthermore, the elastic bodies obtained in Comparative Examples 2 to 4 have a low vibration speed and cannot drive the rotating body.

  The elastic body for an ultrasonic motor of the present invention can be used as an elastic body of an ultrasonic motor provided with an ultrasonic vibrator such as a piezoelectric element.

DESCRIPTION OF SYMBOLS 1 ... Ultrasonic motor 2 ... Piezoelectric element 3 ... Comb-like elastic body 4 ... Stator 5 ... Rotor

Claims (12)

It is fixed to the ultrasonic vibrating body for generating ultrasonic vibration by applying the frequency voltage, and the ultrasonic vibration generated by this ultrasonic vibrating body is transmitted to the moving body as a surface traveling wave to drive this moving body. An elastic body for an ultrasonic motor,
The glass transition temperature is 90 ° C. or more, and both sides of the elastic body formed into a plate shape are fixed by sandwiching them between plate-shaped piezoelectric elements, and the piezoelectric element is loaded with a frequency voltage and oscillated at a resonance frequency to increase the voltage An elastic body made of a thermoplastic resin having a maximum vibration speed of 500 mm / second or more.   The elastic body according to claim 1, wherein the thermoplastic resin is a non-liquid crystal polymer.   The elastic body according to claim 1 or 2, wherein the thermoplastic resin is at least one selected from the group consisting of a polyaryl ketone resin, a polybenzimidazole resin, a polyamideimide resin, and an aromatic polyamide resin.   The elastic body according to any one of claims 1 to 3, wherein the thermoplastic resin is a polyether ether ketone resin.   The elastic body in any one of Claims 1-4 currently formed with the thermoplastic resin whose Izod impact strength (with notch) based on ASTM D256 is 50 J / m or more.   The elastic body according to any one of claims 1 to 5, wherein a tensile elastic modulus based on ISO 527-1 / -2 is 10 to 30 GPa.   It is a shape which has a comb-tooth part, The elastic body in any one of Claims 1-6.   Furthermore, the elastic body in any one of Claims 1-7 containing an inorganic filler.   The elastic body according to claim 8, wherein the inorganic filler is an inorganic fiber, and the proportion of the inorganic filler is 20 to 60 parts by weight with respect to 100 parts by weight of the thermoplastic resin. Elastic bodies according to any one of claims 1 to 9 density is formed in the thermoplastic resin is 3 g / cm ³ or less.   The elastic body according to claim 1, wherein the ultrasonic vibration body is a piezoelectric element, and the moving body is a rotating body.   The ultrasonic motor provided with the elastic body in any one of Claims 1-11.

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