JPH0533689U - Ultrasonic motor - Google Patents

Abstract

(57) [Summary] [Purpose] To obtain a compact, yet low rotation and high torque output. [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 rotatably abuts on the other transmission member 18, and a small-diameter gear 25 is integrated with the rotor 26. The large-diameter gear 20 meshes with the small-diameter gear 25,
A second output shaft 21 to which the gear 20 is attached is rotatably supported around the center of the stator 15.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 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 elliptic 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 ceramics 51 is attached to the surface thereof. A reference numeral 52 designates a transmission member having a rectangular cross section fixed to a position A facing each other on the circumferential surface of the stator 50, and is formed of a plastic in order to obtain a predetermined friction transmission force. A pressing member 53 rotatably supports the pressing roller 54 on a shaft 55 spanned by the shaft 55, and is biased by a compression spring 56 so as to press the pressing roller 54 toward the transmitting member 52. A peripheral surface of a rotor 57 attached to a rotary shaft 58 is rotatably abutted on 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 motion of the stator 50 at the 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 motion.

[0004]

Generally, in the ultrasonic motor using the vibration mode as described above, since the vibration is generated by a high frequency vibration frequency, the rotation obtained from the output shaft is high rotation and low rotation. It has torque characteristics, and in order to obtain high torque rotation at low rotation speed, it is necessary to provide a reduction gear train, and there is a drawback that the overall size becomes large. Further, if the pressing force of the transmission member fixedly attached to the stator to the rotor is increased in order to obtain a high torque, the transmission member is significantly worn out, which shortens the life of the motor. Further, since the output shaft is located at the end portion deviated from the center of the motor, there is a drawback that it is not convenient to use. The present invention has been made in view of the above-mentioned conventional drawbacks and problems, and an object thereof is to provide an ultrasonic motor of a small size, low rotation speed, and high torque.

[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 element for pressing the stator to the rotor side, which is arranged on a surface, and imparts a stretching vibration mode in the radial direction and an in-plane bending vibration mode to the piezoelectric element to generate an elliptic motion on the peripheral surface of the stator. An ultrasonic wave motor for rotating the rotor, comprising: a small-diameter gear that rotates integrally with the rotor; and a large-diameter gear that meshes with the small-diameter gear. The output shaft is rotatably supported around the center of the stator. Further, according to the present invention, a disk-shaped stator having a piezoelectric element, a rotor rotatably supported by contacting with a peripheral surface of the stator, and a rotor disposed on the peripheral surface of the stator opposite to the rotor. And a pressing element that presses the stator to the side of the rotor. The piezoelectric element is given a radial expansion vibration mode and an in-plane bending vibration mode to rotate the rotor by an elliptical motion generated on the peripheral surface of the stator. A sonic motor, the first output shaft to which the rotor is attached, a small-diameter gear attached to the first output shaft, a large-diameter gear that meshes with the small-diameter gear, and a large-sized gear. A second output shaft to which a gear having a diameter is attached and which is rotatably supported at the center of the stator; and a third output shaft to which the presser is rotatable and to which the presser is attached. One of the three output shafts Or is one which was selected as an output shaft.

[0006]

[Action]

 In the present invention, the rotation of the small diameter gear of the rotor is reduced by the large diameter gear, and low rotation and high torque rotation is output from the output shaft centered on the center of the stator.

[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 mounting 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-proof material which is entirely made of an elastic body and has a center 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 denotes a small-diameter gear, the rotor 26 of which 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 to keep the stator 15 horizontal by absorbing the thickness and to function 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 and 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 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 to the rotor 26 as a rotational motion 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 becomes 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 stator 15 is formed by the two points of the rollers 34 and 26 via the transmission members 17 and 18. It is fixed at 1, which improves the efficiency of the motor.

In this embodiment, the fixed shaft 35 that rotatably supports the pressing roller 34 is fixed to the pressing member 30, but as another embodiment, the pressing member 30 is 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 rotate from low rotation to high rotation. It is possible to meet a wide range of needs from low torque to high torque.

[0020]

[Effect of the device]

 As described above, according to the present invention, a small-diameter gear that rotates integrally with a rotor that comes into contact with the stator circumferential surface and rotates due to the elliptical motion of the stator circumferential surface, and a large-diameter gear that meshes with the small-diameter gear The output shaft to which this large diameter gear is attached is rotatably supported with the center of the stator as the center point, so that a low-rotation, high-torque rotation output can be obtained from the output shaft without increasing the size. Obtainable. In addition, high torque rotation can be obtained without increasing the pressing force on the rotor, which reduces wear on the contact surface with the rotor and significantly extends the product life. Further, by appropriately selecting the three output shafts, there is an effect that one motor can meet a wide range of needs from low rotation to high rotation and low torque to high torque.

[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 (2)

[Scope of utility model registration request] 1. A disk-shaped stator having a piezoelectric element,
A rotor, which is in contact with the peripheral surface of the stator and is rotatably supported, and a pressing element, which is arranged on the stator peripheral surface on the side opposite to the rotor and presses the stator toward the rotor side, are provided in the piezoelectric element. In an ultrasonic motor that rotates the rotor by an elliptic motion generated on the peripheral surface of the stator by giving a stretching vibration mode in a direction and an in-plane bending vibration mode, a small-diameter gear that rotates integrally with the rotor, An ultrasonic motor comprising: a small-diameter gear and a large-diameter gear that mesh with each other, and an output shaft to which the large-diameter gear is attached is rotatably supported about the center of the stator. 2. A disk-shaped stator having a piezoelectric element,
A rotor that is rotatably supported by contacting the peripheral surface of the stator
Is installed on the peripheral surface of the stator opposite to the rotor.
And a pressing element that presses the stator on the rotor side.
The piezoelectric element has a radial stretching vibration mode and in-plane bending.
An ellipse generated by applying a vibration mode to the peripheral surface of the stator.
In an ultrasonic motor that rotates the rotor by a circular motion
And a first output shaft to which the rotor is attached,
Of the small diameter gear attached to the first output shaft of the
The large-diameter gear that meshes with the large-diameter gear and this large-diameter gear
Attached and rotatably supported at the center of the stator
The output shaft of 2 and the pusher are rotatable,
And a third output shaft attached to these three outputs.
Characterized by selecting one of the force axes as the output axis
And ultrasonic motor.