JP2007135269A - Stator of ultrasonic motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stator which can enhance the efficiency of an ultrasonic motor while increasing the torque. <P>SOLUTION: In an ultrasonic motor where a rotor is driven by vibrating an oscillating piece touching the rotor with a piezoelectric element, the stator is circular, the oscillating piece is arranged in the circumferential direction of the circular stator, a thin vibration separating band is provided between the oscillating piece and the stator, and the vibration separating band is located on the outside of contact point between the oscillating piece and the rotor in the radial direction of the stator. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a stator for an ultrasonic motor, and more particularly to a stator for an ultrasonic motor characterized by the shape of the stator in contact with the rotor.

  2. Description of the Related Art Conventionally, an ultrasonic motor that can drive a rotor in contact with a stator by vibration of a piezoelectric element on the stator side without using magnetic force has been developed.

  Ultrasonic motors can be used for various purposes by devising the number of stators and the shape of the rotor. For example, disk-type and ring-type rotors are already well known. Recently, development of a spherical ultrasonic motor having a rotor as a sphere has also been advanced.

  A stator of such an ultrasonic motor is formed by, for example, polarizing a predetermined portion of a flat plate-shaped piezoelectric element in a predetermined direction to form an A phase and a B phase as piezoelectric element members. A predetermined voltage is applied to the drive electrode provided for each phase to generate a traveling wave vibration on the elastic vibrating piece on the piezoelectric element member. The rotor in contact with the stator is driven by the vibration of this vibrating piece.

  Patent Documents 1 and 2 disclose the shape of a stator of a conventional ultrasonic motor. The structure of this conventional stator will be described below with reference to FIG.

  FIG. 13 is a perspective view of a stator of a conventional ultrasonic motor.

  As shown in FIG. 13, the conventional stator 203 has a disk shape, and a large number of flat vibrating pieces 233 are provided along the circumference of the stator 203 on the surface of the stator 203 pressed against the rotor. Yes. Each of these vibrating pieces 233 is formed by a slit 233a. Further, a thin vibration separation band 233b is provided between the vibration piece 233 and the fixed portion 234 of the stator 203 fixed to the outside, and the vibration piece 233 is configured to easily vibrate. .

  A piezoelectric element member is provided under these vibrating pieces 233, and the piezoelectric element of the piezoelectric element member expands and contracts by applying a voltage to vibrate the vibrating piece 233. In the ultrasonic motor using the stator 203, the rotor pressed against the vibration piece 233 can be rotated in an arbitrary direction by controlling the vibration of the vibration piece 233.

Japanese Patent Laid-Open No. 7-80793 JP 2000-270569 A

  Conventionally, in an ultrasonic motor, it has been a problem to increase the torque by improving the efficiency. However, as shown in FIG. 13, the stator 203 of the conventional ultrasonic motor has a flat disk-like stator shape, and the rotor is driven by pressing a predetermined portion of the vibrating piece against the rotor. If the pressing force of the rotor is increased for the purpose of increasing torque, the deformation of the stator impedes vibrations, resulting in a problem of torque reduction.

  The present invention has been made in view of the above points, and provides a stator capable of improving the efficiency of an ultrasonic motor and increasing torque by adopting a shape in which vibration is not easily inhibited by a pressing force. Objective.

  In the stator of an ultrasonic motor that drives the rotor by vibrating a vibrating piece in contact with the rotor by a piezoelectric element, the stator is circular, and the vibrating piece is arranged in a circumferential direction of the circular stator, A thin vibration isolation band is provided between the vibration piece and the fixed portion of the stator, and the position of the vibration isolation band in the diameter direction of the stator is outside the contact point between the vibration piece and the rotor. It is characterized by being.

  In the stator of an ultrasonic motor that drives the rotor by vibrating a vibrating piece in contact with the rotor by a piezoelectric element, a thin vibration isolation band is provided between the vibrating piece and a fixed portion of the stator. The direction of the vibration isolation band is different from the direction perpendicular to the pressing force between the stator and the rotor.

  In the stator of an ultrasonic motor that drives the rotor by vibrating a vibrating piece in contact with the rotor by a piezoelectric element, a thin vibration isolation band is provided between the vibrating piece and a fixed portion of the stator. Furthermore, a window which is a through hole is provided in the vibration isolation band.

  ADVANTAGE OF THE INVENTION According to this invention, the stator of the ultrasonic motor which can increase a torque can be provided by making the shape of the stator which contact | connects a rotor different from the past.

  That is, according to the present invention, resistance to the pressing force that presses the rotor against the stator is improved, and the vibration of the vibrating piece is hardly hindered, so that a larger pressing force can be applied and the torque of the ultrasonic motor can be increased. it can.

  In addition, according to the present invention, the holding force and rigidity of the rotor by the stator are improved, and the contact state between the stator and the rotor is further stabilized.

  Further, according to the present invention, the area of the piezoelectric element provided in the stator can be increased, and the torque of the ultrasonic motor can be increased.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a perspective view schematically showing an ultrasonic motor according to an embodiment of the present invention.

  As shown in FIG. 1, the ultrasonic motor 1 according to the present embodiment rotates a rotor 2 that is a sphere on a stator 3.

  A large number of vibrating pieces 33 shown in FIG. 3 are provided on the surface of the stator 3 that comes into contact with the rotor 2, and the vibrating pieces 33 vibrate to generate traveling waves, whereby the rotor 2 is rotated. The stator 3 is fixed to the pedestal 4.

  FIG. 2 is a side sectional view of the ultrasonic motor 1 shown in FIG.

  In this embodiment, as shown in FIG. 2, the stator 3 is fixed to the pedestal 4 with screws, but the present invention is not limited to this embodiment, and the stator 3 is attached in any way. There may be.

  FIG. 3 is a perspective view of the stator 3 shown in FIG. 1 as viewed from the contact surface of the rotor 2.

  FIG. 4 is a plan view of the stator 3 shown in FIG. 1 as viewed from the contact surface of the rotor 2.

  FIG. 5 is a cross-sectional view of the stator 3 shown in FIG.

  As shown in FIG. 3, the stator 3 has a conical shape with a conical tip cut out (hereinafter referred to as “cage type”), and is configured to come into contact with the rotor 2 at the recessed portion. .

  As can be seen with reference to FIGS. 3, 4, and 5, a large number of vibrating pieces 33 are provided on the contact surface of the stator 3 with the rotor 2. Each of these vibrating pieces 33 is formed by a slit 33a. Further, a thin vibration isolation band 33b is provided between the vibration piece 33 and the fixed portion 34 of the stator 3 fixed to the pedestal 4 so that the vibration piece 33 can easily vibrate. Yes.

  A piezoelectric element (not shown) is provided under the vibrating piece 33, and the piezoelectric element expands and contracts by applying a voltage to vibrate the vibrating piece 33. In the ultrasonic motor 1, the rotor 2 can be rotated in an arbitrary direction by controlling this vibration.

  Next, the effect of this embodiment will be described with reference to the drawings.

  FIG. 6 is an enlarged cross-sectional view of a portion where the conventional stator 203 shown in FIG. 13 is in contact with the rotor 2.

  FIG. 7 is an enlarged cross-sectional view showing a portion where the stator 3 of the present embodiment shown in FIG.

  In an ultrasonic motor, the rotor is pressed against a stator that has generated a traveling wave to obtain a driving force by frictional force. it can.

  However, in the conventional stator 203, as shown in FIG. 6, even if the pressing force between the vibrating piece 233 and the rotor 2 is increased, the vibration separating band 233b bends and vibrates as shown by a two-dot chain line in FIG. The piece 233 is warped outward, and the strength of contact between the vibrating piece 233 and the rotor 2 cannot be increased.

  On the other hand, in the present embodiment, as shown in FIG. 7, when the pressing force between the vibrating piece 33 and the rotor 2 is increased, the vibration separating band 33b as shown by a two-dot chain line in FIG. Is bent and the vibrating piece 33 is warped inward to wind the rotor 2, so that the strength of contact between the vibrating piece 33 and the rotor 2 can be increased. This is because in the stator 3 of the present embodiment, the position of the vibration isolation band 33 b in the diameter direction of the stator 3 is outside the contact point between the vibrating piece 33 and the rotor 2.

  Further, in the conventional stator 203, since the direction of the vibration separating band 233b is perpendicular to the pressing force, it is easy to bend by the pressing force, but in the stator 3 of the present embodiment, the direction of the vibration separating band 33b. Is not in a direction perpendicular to the pressing force, it can be made difficult to bend even if the pressing force is received, and a stable torque can be obtained.

  FIG. 8 is a bar graph comparing the torque of the conventional ultrasonic motor shown in FIG. 6 with the torque of the ultrasonic motor of the present embodiment shown in FIG. The horizontal axis indicates whether the ultrasonic motor is the conventional ultrasonic motor shown in FIG. 6 or the ultrasonic motor of the present embodiment shown in FIG. 7, and the vertical axis indicates the torque of the ultrasonic motor.

  According to the configuration shown in FIG. 7, the strength of contact between the resonator element 33 and the rotor 2 can be increased, and the torque of the ultrasonic motor can be increased as compared with the conventional case as shown in FIG. .

  Next, an embodiment different from FIG. 3 of the present invention will be described.

  FIG. 9 is a perspective view of the stator 103 of the ultrasonic motor according to the present invention, as viewed from the rotor contact surface, which is a stator 103 according to another embodiment of FIG.

  FIG. 10 is a plan view of the stator 103 shown in FIG. 9 as seen from the rotor contact surface.

  Further, FIG. 11 is a YY sectional view of the stator 103 shown in FIG.

  In this embodiment, the relationship between the rotor 2 and the pedestal 4 is the same as that shown in FIG.

  As shown in FIG. 9, the stator 103 of this embodiment is a cage type in which a conical tip is cut and recessed as in the embodiment of FIG. 3, and the rotor 2 is in contact with the recessed portion. The rotor 2 is configured to be pressed.

  As can be seen with reference to FIGS. 9, 10, and 11, a large number of vibrating pieces 133 are provided on the surface of the stator 103 that is pressed against the rotor 2. Each of these vibrating pieces 133 is formed by a slit 133a. In addition, a thin vibration isolation band 133b is provided between the vibrating piece 133 and the fixed portion 134 of the stator 103 fixed to the pedestal 4 so that the vibrating piece 133 can easily vibrate. Yes.

  In the stator 103 of the present embodiment, a window 133c that is a through hole is further provided in the vibration isolation band 133b. By providing the window 133c, the vibrating piece 133 is more easily vibrated by the piezoelectric element than in the embodiment of FIG.

  FIG. 12 is a line graph showing the relationship between the pressing force and the torque by comparing the embodiment shown in FIG. 3 with the embodiment shown in FIG. The horizontal axis indicates the pressing force between the stator and the rotor, and the vertical axis indicates the torque of the ultrasonic motor.

  As can be seen with reference to FIG. 12, a stronger pressing force is obtained when the stator 103 of the embodiment shown in FIG. 9 is used than when the stator 3 of the embodiment shown in FIG. 3 is used. A large torque can be generated.

1 is a perspective view schematically showing an ultrasonic motor according to an embodiment of the present invention. It is a sectional side view of the ultrasonic motor 1 shown in FIG. FIG. 2 is a perspective view of the stator 3 shown in FIG. 1 as viewed from the direction in which the stator 3 is pressed against the rotor 2. FIG. 2 is a plan view of the stator 3 shown in FIG. 1 as viewed from the direction in which the stator 3 is pressed against the rotor 2. It is XX sectional drawing of the stator 3 shown in FIG. FIG. 14 is an enlarged cross-sectional view of a portion where the conventional stator 203 shown in FIG. 13 is in contact with the rotor 2. FIG. 4 is an enlarged cross-sectional view of a portion where the stator 3 of the present embodiment shown in FIG. 3 is in contact with a rotor 2. It is the bar graph which compared the torque of the conventional ultrasonic motor shown in FIG. 6, and the torque of the ultrasonic motor of this Embodiment shown in FIG. FIG. 4 is a perspective view of the stator of the ultrasonic motor according to the present invention as seen from the direction in which the stator 103, which is an embodiment different from FIG. 3, is pressed against the rotor. It is the top view which looked at the stator 103 shown in FIG. 9 from the direction pressed on a rotor. FIG. 11 is a YY sectional view of the stator 103 shown in FIG. 10. FIG. 10 is a line graph comparing the embodiment shown in FIG. 3 with the embodiment shown in FIG. 9 and showing the relationship between pressing force and torque. It is a perspective view of the stator of the conventional ultrasonic motor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ultrasonic motor 2 Rotor 3 Stator 4 Base 33 Vibrating piece 33a Slit 33b Vibration separation zone 34 Fixed part

Claims (4)

In the stator of the ultrasonic motor that drives the rotor by vibrating the vibrating piece in contact with the rotor by a piezoelectric element,
The stator is circular, and the resonator element is disposed in a circumferential direction of the circular stator;
A thin vibration isolation band is provided between the vibrating piece and the fixed portion of the stator,
The stator of an ultrasonic motor, wherein a position of the vibration separating band in a diameter direction of the stator is outside a contact point between the vibrating piece and the rotor. In the stator of the ultrasonic motor that drives the rotor by vibrating the vibrating piece in contact with the rotor by a piezoelectric element,
A thin vibration isolation band is provided between the vibrating piece and the fixed portion of the stator,
The ultrasonic motor stator according to claim 1, wherein a direction of the vibration isolation band is different from a direction perpendicular to a pressing force between the stator and the rotor. In the stator of the ultrasonic motor that drives the rotor by vibrating the vibrating piece in contact with the rotor by a piezoelectric element,
A thin vibration isolation band is provided between the vibrating piece and the fixed portion of the stator,
Further, a stator of an ultrasonic motor, wherein a window which is a through hole is provided in the vibration isolation band. An ultrasonic motor comprising the stator according to claim 1, wherein the rotor is driven by the stator.

Images