JPH0533690U - Ultrasonic motor - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the transmission efficiency from the stator to the rotor and to stabilize the product life. [Structure] Piezoelectric ceramics 16 is adhered to the surface of the stator 15, and plastic transmission members 17 and 18 are adhered to the peripheral surface at positions facing each other. The pressure roller 34 is pressed against the transmission member 17 toward the other transmission member 18 side. A rotor 26 attached to the first output shaft 27 is rotatably abutted on the other transmission member 18. Then, the surfaces 17a and 18a of the transmission members 17 and 18 which come into contact with the pressing roller 34 and the rotor 26.
Is an arcuate concave surface.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an ultrasonic motor in which a piezoelectric element is given a radial stretching vibration mode and an in-plane bending vibration mode to rotate a rotor by an elliptical motion generated on the peripheral surface of the piezoelectric element.

[0002]

[Prior Art]

 FIG. 5 is a plan view showing a schematic configuration of a conventional ultrasonic motor. In the figure, reference numeral 50 is a disk-shaped stator, and a donut-shaped piezoelectric ceramic 51 is attached to the surface thereof. Reference numeral 52 denotes a transmission member having a rectangular cross section, which is fixed to points A on the circumferential surface of the stator 50 facing each other, and is made of plastic to obtain a predetermined friction transmission force. Reference numeral 53 denotes a pressing member that rotatably supports the pressing roller 54 on a shaft 55 that is bridged, and is biased by a compression spring 56 so that the pressing roller 54 is pressed toward the transmission member 52 side. A peripheral surface of a rotor 57 attached to a rotary shaft 58 rotatably contacts the other transmission member 52, and the rotary shaft 58 that rotates integrally with the rotor 57 is pivotally supported by a case (not shown). Project from the case to form the output shaft.

In such a structure, the piezoelectric ceramic 51 has a radial stretching vibration mode as shown in FIG. 6A and an in-plane bending vibration mode in the vertical direction as shown in FIG. 6B. When the phases of these vibration frequencies are shifted, as shown in FIG. 6 (c), at two points (point A in the figure) on the circumferential surface on the horizontal line passing through the center line of the stator 50, the directions are opposite to each other. A rotating elliptical motion occurs. The elliptical movement of the stator 50 at point A is transmitted to the rotor 57 via the transmission member 52 and can be taken out from the output shaft 58 as a rotational movement.

[0004]

However, in the above-described conventional ultrasonic motor, the shape of the transmission member of the stator, which is sandwiched between the rotor and the pressing roller and pressed by the rotor and the pressing roller, has a simple rectangular cross section. The transmission member, the rotor, and the pressing roller are in point contact with each other. For this reason, there is a drawback in that the fixing of the stator becomes unstable, and the elliptical movement of the stator circumferential surface is not sufficiently transmitted to the rotor, resulting in poor transmission efficiency. Further, the transmission member is heavily worn at the contact portion with the rotor and the pressing roller, which causes a problem that the product life of the motor is shortened. The present invention has been made in view of the above-mentioned conventional drawbacks or inconveniences, and an object of the present invention is to provide an ultrasonic motor that enhances the transmission efficiency from the stator to the rotor and stabilizes the product life. It is in.

[0005]

[Means for Solving the Problems]

 To achieve this object, the present invention provides a disk-shaped stator having a piezoelectric element, a rotor rotatably supported in contact with a peripheral surface of the stator, and a stator peripheral surface opposite to the rotor. A pressing member that is disposed on a surface and presses the stator toward the rotor, and a transmission member that is attached to a portion of the peripheral surface of the stator where the rotor and the pressing member contact, and the piezoelectric element expands and contracts in the radial direction. An ultrasonic motor that applies a vibration mode and an in-plane bending vibration mode to rotate the rotor through the transmission member by an elliptic motion generated on the peripheral surface of the stator, wherein the rotor of the transmission member and the rotor The surface with which the presser abuts is an arcuate concave surface.

[0006]

[Action]

 Since the portion of the transmission member that comes into contact with the rotor and the pusher is an arcuate concave surface, the contact portion changes from point contact to surface contact.

[0007]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. 1 is an exploded perspective view of an ultrasonic motor according to the present invention, FIG. 2 is a plan view of the same, FIG. 3 is a plan sectional view of the same, and FIG. 4 is a side sectional view of the same. In these figures, 1 is a case having an opening in the upper part, which is composed of a bottom surface portion 2 and a side surface portion 6. A keyhole-shaped bearing hole 3 having a slit 3a is bored in the central portion of the bottom surface portion 2, and another bearing hole 4 is bored in the end portion. Bearings 10a and 10b are fitted and fixed in the bearing holes 3 and 4, respectively. Two screw holes 6b are provided in the right side surface portion 6a of the side surface portion 6, and a pair of thick-walled mounting portions 7 are provided from the left side surface portion to the upper and lower side surface portions, and a pair of protruding portions are provided on the upper and lower side surface portions so as to face each other. Guide portions 8 are provided respectively. A screw hole 7a is provided on the upper surface of the placing portion 7, a screw hole 8a is provided on the upper surface of the guide portion 8, and a guide surface is provided on the opposing surface 8b.

Reference numeral 12 is a thin plate vibration isolator which is entirely made of an elastic body, and has a central hole 12a. Reference numeral 15 is a disk-shaped stator having a central hole 15a, and donut-shaped piezoelectric ceramics 16 are attached to the front surface and the back surface. A rectangular transmission member made of a pair of plastics is fixed to the circumferential surface of the stator 15 at positions facing each other, and an outer end surface 18a of the transmission member is formed into an arcuate concave surface. Reference numeral 19 is a lead wire electrically connected to the piezoelectric ceramics 16.

A large-diameter gear 20 is attached to the second output shaft 21. Reference numeral 26 is a small-diameter gear, and the rotor 26 is integrally formed on the lower surface thereof, and is attached to the first output shaft 27.

A pressing member 30 is provided with a through hole 31 in the center and a pair of leg portions 32 formed on the left side portion so as to project in a divergent manner. A guide surface is provided on the side surface 32a of the leg portion 32, and a contact surface is provided on the surface 32b orthogonal to the guide surface 32a. Further, a collar 33, part of which is embedded in the pressing member 30, projects at a substantially central height position sandwiched by the leg portions 32 of the pressing member 30. A fixed shaft 35 is press-fitted and fixed in the through hole 31 of the pressing member 30, and a pressing roller 34, which is a pressing member, is rotatably supported on the fixed shaft 35. 37 is a U-shaped spring.

Reference numeral 40 denotes a flat plate-shaped cover, in which bearing holes 41 and 42 are formed at positions corresponding to the bearing holes 3 and 4 of the case 1, and a screw mounting hole 43 into which a screw 45 is inserted. Has been drilled. 44a and 44b are bearings fitted and fixed in the bearing holes 41 and 42.

The assembly method will be described below. First, the bearings 10a and 10b are fitted and fixed in the bearing holes 3 and 4 of the case 1, respectively. Next, the vibration-damping material 12 and the stator 15 are placed in a laminated state and placed on the bottom plate 3 while aligning the respective central holes 12a and 15a with the bearing holes 3 of the bottom plate 3 of the case 1. At the same time, the lead wire 19 of the stator 15 is led out of the case 1 through the slit 3 a of the bearing hole 3. At this time, the vibration-damping material 12 formed of an elastic body has a vibration-damping function for the motor body, protects the lead wire 19 and insulates it at the same time, and further, the lead wire 19 and the piezoelectric ceramic 16 are soldered together. It functions as a spacer for absorbing the thickness and keeping the stator 15 horizontal, and as a spacer for preventing the stator 15 from coming into contact with the bearing 10a of the case 1.

Subsequently, the first output shaft 27 of the small diameter gear 25 is inserted into the bearing 10b of the case 1 so as to be rotatably supported. At this time, the peripheral surface of the rotor 26 is positioned in contact with the transmission member 18 of the stator 15. Next, the pressing member 30 is housed in the case 1 so that the guide surface 32a of the leg portion 32 of the pressing member 30 is sandwiched between the guide surfaces 8b of the guide portions 8 of the case 1. Then, the U-shaped spring 37 is housed between the guide portion 8 of the case 1 and the right side surface portion 6a, and the screw 38 is screwed into the screw hole 6b to press the tip of the spring 37 at one end side.

As a result, as shown in FIG. 3, the other end of the spring 37 presses the contact surface 32b of the leg portion 32 of the pressing member 30 and presses the pressing member 30 toward the stator 15 side using the guide surface 8a as a guide. Therefore, the pressing roller 34 presses the transmission member 17 toward the rotor 26 side and presses the other transmission member 18 against the peripheral surface of the rotor 26 with a predetermined pressing force. This pressing force is adjusted by advancing and retracting the screw 38 from the side surface portion 6a. At this time, the outer end surfaces 17a and 18a of the transmission members 17 and 18 are formed into arcuate concave surfaces. The pressing roller 34 and the rotor 26 that are in pressure contact with the outer end surfaces 17a and 18a form the stator 15 as shown in FIG. It is fixedly held in the case 1 with its movement in the left, right, up and down directions restricted.

Further, the brim 33 of the pressing member 30 is located on the upper end surface of the stator 15 to prevent the stator 15 from floating upward. Next, the second output shaft 21 of the large-diameter gear 20 is inserted into the bearing 10a of the case 1 and rotatably supported. Finally, the cover 40 is put on the case 1 and attached to the case 1 with the screw 45, and the first and second output shafts are fitted to the bearings 44a and 44b to be rotatably supported.

The operation will be described below. When a voltage is applied to the piezoelectric ceramics 16 to provide a radial stretching vibration mode and an in-plane bending vibration mode, and the phases of these vibration frequencies are shifted, the transmission members 17, 18 of the stator 15 are fixed. Elliptical motion occurs on the circumferential surface. This elliptical motion is transmitted as a rotational motion to the rotor 26 via the transmission member 18 pressing the rotor 26 with a predetermined pressing force. This rotation operation is output as high rotation from the first output shaft 27, and at the same time, is transmitted to the large-diameter gear 20 via the small-diameter gear 25 to rotate the second output shaft 21. The rotation output to the second output shaft 21 is reduced by the large-diameter gear 20 and output as low rotation and high torque. In this case, the reduction ratio can be appropriately selected by changing the gear ratio between the small diameter gear 25 and the large diameter gear 20.

As described above, the second output shaft 21 outputs low-rotation and high-torque rotation, so that in order to obtain high torque, the pressing force of the transmission member 18 on the rotor 26 is increased more than necessary. Since it is not increased, unnecessary wear of the transmission members 17, 18 can be prevented. Further, since the outer end surfaces 17a and 18a of the transmission members 17 and 18 are arcuate concave surfaces, the contact between the pressing roller 34 and the rotor 26 is a surface contact, which increases the friction transmission force to the rotor 26, Also, the pressing force of the transmission member 18 against the rotor 26 is not increased more than necessary. Further, because of the surface contact, the wear of the transmission members 17, 18 is reduced.

Further, the stator 15 that vibrates by the reaction force that rotates the rotor 26 via the transmission member 18 is conventionally provided with rubber or the like in the central hole 15 a of the stator 15 or a part of the outer periphery of the stator 15. Although it was elastically held to prevent vibration, the holding was not perfect, and the position of the stator 15 was not fixed. For this reason, the force by which the stator 15 rotates the rotor 26 and the force by which the stator 15 itself moves slightly The efficiency of the motor was reduced. In the present embodiment, the outer end surfaces 17a and 18a of the transmission members 17 and 18 are arcuate concave surfaces, so that the upper and lower sides of the stator 15 and the left and right movements of both rollers 34 and 34 via the transmission members 17 and 18. It is regulated by two points such as No. 26 and is firmly fixed to the case 1 to improve the transmission efficiency of the transmission member to the rotor.

Further, in this embodiment, the fixed shaft 35 rotatably supporting the pressing roller 34 is fixed to the pressing member 30, but as another embodiment, the pressing member 30 is provided. A bearing is provided, the fixed shaft 35 is rotatably supported by the bearing, the pressing roller 34 is attached to the fixed shaft 35, and the tip of the fixed shaft 35 is extended to the outside of the case 1. 35 can function as a third output shaft. In this case, since the pressing member 30 is biased by the spring 37 and can be slightly moved, the rotation obtained from the third output shaft 35 is lower than the rotation obtained from the first output shaft 27.

With such a configuration, by appropriately selecting the above-described first and second output shafts 27 and 21 and the third output shaft 35, one motor can drive from low rotation to high rotation. It is possible to meet a wide range of needs for rotation and low torque to high torque. In the present embodiment, the structure in which rotation is possible not only from the first output shaft 27 but also from the second output shaft 21 is described. However, the structure is not limited to this, and is a conventional general structure. It goes without saying that the present invention can be applied to an ultrasonic motor having only the first output shaft 27.

[0021]

[Effect of the device]

 As described above, according to the present invention, the contact portion of the transmission member with the rotor and the pressing member is formed into an arcuate concave surface, so that the contact portion is changed from point contact to surface contact. The transfer operation from the member to the rotor is stabilized, and the transfer efficiency is improved. Further, the wear of the transmission member at the contact portion is reduced, and the pressing force on the rotor can be reduced due to the improvement of the friction transmission force due to the surface contact, so that the product life of the motor can be extended. Further, the fixing of the stator sandwiched between the rotor and the presser is stable, and the transmission operation from the stator is not dispersed, which has the effect of improving the transmission efficiency of the transmission member to the rotor.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an ultrasonic motor according to the present invention.

FIG. 2 is a plan view of an ultrasonic motor according to the present invention.

FIG. 3 is a plan sectional view of an ultrasonic motor according to the present invention.

FIG. 4 is a side sectional view of an ultrasonic motor according to the present invention.

FIG. 5 is a plan view showing a schematic configuration of a conventional ultrasonic motor.

FIG. 6 is an explanatory diagram showing the operating principle of the ultrasonic motor.

[Explanation of symbols]

 1 Case 12 Vibration Isolator 15 Stator 16 Piezoelectric Ceramics 18 Transmission Member 18a Outer End Surface 20 Large Diameter Gear 21 Second Output Shaft 25 Small Diameter Gear 27 First Output Shaft 30 Pressing Member 34 Pressing Roller 40 Cover

Claims (1)

[Scope of utility model registration request] 1. A disk-shaped stator having a piezoelectric element,
A rotor rotatably supported in contact with the peripheral surface of the stator, a pressing element arranged on the stator peripheral surface on the side opposite to the rotor and pressing the stator toward the rotor side, the rotor on the peripheral surface of the stator. A transmission member attached to a portion where the rotor and the pressing element come into contact with each other, and the piezoelectric element is provided with a radial expansion / contraction vibration mode and an in-plane bending vibration mode to generate an elliptical motion on the peripheral surface of the stator. An ultrasonic motor that rotates the rotor via a transmission member, wherein a surface of the transmission member that contacts the rotor and the pressing element is an arcuate concave surface.