JPH07170764A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To provide an ultrasonic motor, operation of which is stabilized at all times and which has high efficiency, by solving a problem that vibrations are not transmitted to a moving body efficiently because the vibrations of a vibrator are disturbed due to the accuracy of machining of a part, the fluctuation of external load, etc., efficiency is deteriorated and stability is lowered and keeping a contact between the vibrator and the moving body constant. CONSTITUTION:A spherical or conical projection 15 is formed at the central section of a vibrator 14 while the vibrator is held by a support substrate 16 with a circular recessed surface 16a rotatably engaged with the projection, thus keeping a contact between the vibrator 14 and a moving body 17 constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic motor for generating driving force by exciting elastic waves using a piezoelectric body such as a piezoelectric ceramic, and more particularly to a method for supporting a vibrating body.

[0002]

2. Description of the Related Art In recent years, attention has been paid to ultrasonic motors that use elastic vibration as a driving force by vibrating a vibrating body made of a piezoelectric material. Hereinafter, a conventional technique of an ultrasonic motor will be described with reference to the drawings.

FIG. 7 is a cross-sectional view of a main part structure of a conventional disc type ultrasonic motor. In the figure, reference numeral 1 denotes a vibrating body, in which a plurality of protrusions 2a are formed on one surface of a disk-shaped elastic substrate 2 and a traveling wave of flexural vibration of radial primary, circumferential tertiary or higher is excited on the other surface. The disk-shaped piezoelectric body 3 is bonded and configured.

Reference numeral 4 denotes a moving body made of composite plastic or metal, and both ends thereof are press-fitted and locked to a rotary shaft 7 held by bearings 5 and 6. The moving body 4 is brought into pressure contact with the projection 2a of the vibrating body 1 by the coil spring 8, and the vibrating body 1 is pressed against the support substrate 10 via the felt 9 and locked by the frictional force.

The felt 9 is for locking without vibrating the vibration of the vibrating body. 10 is a housing.

When an AC voltage is applied to the driving electrode formed on the piezoelectric body 3, an elastic traveling wave is excited in the vibrating body 1, and the displacement component in the circumferential direction of this traveling wave is expanded by the projecting body 1a and the moving body is moved. 4 is rotated by being driven by frictional force, and the rotary shaft press-fitted and locked by this is also rotated to take out an output.

[0007]

As described above, since the ultrasonic motor transmits the displacement due to the vibration of the vibrating body to the moving body by the frictional force, stable and uniform contact between the moving body and the vibrating body is important. is there. In other words, how accurately the parallelism between the moving body and the protrusion of the vibrating body is maintained and the pressure is applied greatly affects the characteristics.

However, the conventional ultrasonic motor is
The position of the vibrating body was only fixed through a substance such as felt, and due to processing errors of the supporting substrate, uneven thickness of the felt, and uneven bonding of the piezoelectric body, as shown in FIG. A large error occurs in the parallelism, a part of the felt is deformed unevenly due to pressure contact, it is not possible to obtain a uniform contact, efficiency is low, vibration occurs and rotation speed does not increase, There was a problem that noise was generated and uneven rotation was generated.

Further, the vibrating body is fixed only by frictional engagement through the felt, the position of the vibrating body sometimes shifts, and the felt is compressed and deformed due to constant pressure, resulting in deterioration of characteristics over time. There was a problem that it would end up.

An object of the present invention is to solve the above problems and to provide a highly efficient ultrasonic motor which is always stable in operation by keeping the contact between the vibrating body and the moving body uniform.

[0011]

In order to solve the above-mentioned problems, an ultrasonic motor of the present invention forms a spherical or conical projection in the center of a vibrating body and rotatably engages with the projection. The vibrating body is held by a supporting substrate having a circular concave surface.

In the ultrasonic motor of the present invention, a circular concave surface is formed at the center of the vibrating body, and the vibrating body is formed by a support substrate having a spherical or conical projection that rotatably engages with the concave surface. Is held.

In the ultrasonic motor of the present invention, the central portion of the vibrating body is rotatably engaged with and held by the supporting substrate by a thin plate-shaped elastic member.

[0014]

According to the above means, by supporting the vibrating body only at the center portion where the vibration amplitude is the smallest, it is possible to minimize the vibration amplitude inhibition without using the felt as in the conventional case. It is possible to prevent displacement of the vibrating body with time and deterioration of characteristics with time. Further, since the vibrating body is rotatably held on the support substrate, the vibrating body automatically acts on the contact surface of the moving body when the moving body is pressed and contacted by the spring pressure. Even if there is a factor such as an error, an extremely uniform contact state can be realized.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view of an ultrasonic motor according to a first embodiment of the present invention. In FIG. 1, reference numeral 12 is a disk-shaped elastic substrate made of metal, and one side thereof is provided with a projection 12a in a circumferential shape for expanding displacement.

On the other surface of the elastic substrate 12, a piezoelectric ceramic 13 as a driving piezoelectric body is bonded by an adhesive or the like to form a vibrating body 14. At the center of the vibrating body 14, a resin spherical projection 15 having a small hole at the center is press-fitted and fixed.

Reference numeral 16 is a support substrate, which has a tapered surface 16a at its center so that the spherical projection 15 is rotatably engaged and held.
Are formed.

Reference numeral 17 denotes a moving body made of composite plastic or metal, which is press fitted and locked to the rotary shaft 18. Both ends of the rotary shaft 18 are held by bearings 19 and 20. The bearings 19 and 20F are press-fitted and fixed to the support substrate 16 and the housing 22. The moving body 17 is in pressure contact with the protrusion 2a of the vibrating body by the coil spring 21.

When an AC voltage is applied to the drive electrode formed on the piezoelectric body 13, an elastic traveling wave is excited in the vibrating body 14,
The circumferential displacement component of the traveling wave is enlarged by the projection 12a, and the moving body 17 is driven by the frictional force proportional to the applied pressure to rotate, and the rotary shaft press-fitted and locked to this also rotates and outputs. Can be taken out.

The vibrating body 14 is rotatably held as described above, and when the moving body 17 pressurizes the vibrating body 14, the moving body 17 automatically follows the moving body 17, and there are factors such as machining errors. However, it is possible to realize a very uniform contact state. As a result, stable and highly efficient rotation can be obtained.

Instead of the tapered surface 16, a spherical seat as shown in FIG. 2 may be used. Furthermore, as shown in FIG. 3, the same effect can be obtained by combining a conical projection and a circular hole.

FIG. 4 is a sectional view of an ultrasonic motor according to the second embodiment of the present invention. In FIG. 4, reference numeral 23 denotes a disk-shaped elastic substrate made of metal, and one surface thereof is provided with a protrusion 23a in a circumferential shape for expanding displacement. Further, on the other surface of the elastic substrate 23, a piezoelectric ceramic 24 as a driving piezoelectric body is bonded by an adhesive or the like to form a vibrating body 25.
Is configured. A circular concave surface (tapered surface) 23b is formed at the center of the vibrating body 25.

Reference numeral 26 is a support substrate, on which a spherical protrusion 27 made of resin having a small hole in the center is press-fitted and fixed. The vibrating body 2
5 is rotatably engaged and held by the spherical projection.

Reference numeral 28 denotes a moving body made of composite plastic or metal, which is press fitted and locked to the rotary shaft 29. Both ends of the rotary shaft 29 are held by bearings 30 and 31. The moving body 28 is brought into pressure contact with the projecting body 23a of the vibrating body by the coil spring 32. 33 is a housing.

When an AC voltage is applied to the drive electrode formed on the piezoelectric body 24, an elastic traveling wave is excited in the vibrating body 25,
The circumferential displacement component of the traveling wave is enlarged by the projection 23a, the moving body 28 is driven by the frictional force proportional to the applied pressure to rotate, and the rotary shaft 29 press-fitted and locked thereto also rotates. You can retrieve the output.

The vibrating body 25 is rotatably held as described above, and when the moving body 28 pressurizes the vibrating body 25, it automatically follows the moving body 28, and there are factors such as machining errors. However, it is possible to realize a very uniform contact state. As a result, stable and highly efficient rotation can be obtained.

FIG. 5 is a sectional view of an ultrasonic motor according to a third embodiment of the present invention. In FIG. 5, reference numeral 34 denotes a disk-shaped elastic substrate made of metal, and one surface thereof is provided with a protrusion 34a in a circumferential shape for expanding displacement.

On the other surface of the elastic substrate 34, a piezoelectric ceramic 35 as a driving piezoelectric body is bonded by an adhesive or the like to form a vibrating body 36. A hollow bush 37 is press-fitted and fixed to the center of the vibrating body 36.

Reference numeral 38 denotes a support substrate, and the bush 37 is rotatably held by an elastic thin plate 39 made of stainless steel and having a thickness of 0.05 mm as shown in FIG. The elastic thin plate 39 is the inner circumference,
The outer periphery is press-fitted and fixed to the bush 37 and the support substrate 38, respectively.

Reference numeral 40 denotes a moving body made of composite plastic or metal, which is press fitted and locked to the rotary shaft 41. Both ends of the rotary shaft 41 are held by bearings 42 and 43. The vibrating body 36 is in pressure contact with the moving body 40 of the vibrating body by the coil spring 44. 45 is a housing.

When an AC voltage is applied to the drive electrode formed on the piezoelectric body 35, an elastic traveling wave is excited in the vibrating body 36,
The circumferential displacement component of the traveling wave is enlarged by the protrusion 34a, the moving body 40 is driven by the frictional force proportional to the pressing force to rotate, and the rotary shaft 41 press-fitted to this also rotates. You can retrieve the output.

The vibrating body 36 has the elastic thin plate 39 as described above.
It is rotatably held by the moving body 27, and when the moving body 27 pressurizes the vibrating body 24, the moving body 27 automatically follows the moving body 27, and an extremely uniform contact state is realized even if there are factors such as machining errors. be able to. Further, the vibrating body 36 is supported by the elastic thin plate 39 so as not to be displaced in the radial direction, and since there is no deformation such as felt, there is no characteristic change with time. As a result, stable and highly efficient rotation can be obtained.

[0034]

EFFECTS OF THE INVENTION By forming a spherical or conical projection at the center of the vibrating body and holding the vibrating body by a support substrate having a circular concave surface that rotatably engages with the projection, As described above, it is possible to minimize the vibration amplitude inhibition without using the felt, and to prevent the positional displacement of the vibrating body with time and the characteristic deterioration with time.

Further, since the vibrating body is rotatably held on the support substrate by the spherical projection, the vibrating body is automatically brought into contact with the vibrating body by pressing the moving body with the vibrating body by spring pressure. It has a flattening action, and can achieve a very uniform contact state between the vibrating body and the moving body even if there are factors such as machining errors. As a result, it is possible to realize a highly efficient ultrasonic motor whose operation is always stable.

Further, a circular concave surface is formed in the center of the vibrating body, and the vibrating body is held by a supporting substrate having a spherical or conical projection that rotatably engages with the concave surface. It is possible to minimize the inhibition of vibration amplitude without using a felt, and to prevent positional displacement of the vibrating body over time and deterioration of characteristics over time.

Further, since the vibrating body is rotatably held by the spherical protrusion of the supporting substrate, the vibrating body is automatically vibrated on the contact surface of the moving body by pressing the moving body with the vibrating body by spring pressure. It has a function of conforming to the body, and it is possible to realize a very uniform contact state between the vibrating body and the moving body even if there are factors such as machining errors. As a result, it is possible to realize a highly efficient ultrasonic motor whose operation is always stable.

Further, since the center portion of the vibrating body is rotatably engaged with and held by the supporting substrate by the elastic member in the shape of a thin plate, the vibration amplitude inhibition can be minimized without using a felt as in the conventional case. As a result, it is possible to prevent positional displacement of the vibrating body over time and deterioration of characteristics over time.

Further, since the vibrating body is rotatably held on the support substrate, the vibrating body is automatically arranged on the contact surface of the moving body by pressing the moving body with the vibrating body by spring pressure. It is possible to realize a very uniform contact state between the vibrating body and the moving body, even if there is a factor such as a machining error. As a result, it is possible to realize a highly efficient ultrasonic motor whose operation is always stable.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a main part configuration of an ultrasonic motor according to a first embodiment of the present invention.

FIG. 2 is a partial sectional view of an example of holding a vibrating body of the motor of the embodiment.

FIG. 3 is a partial cross-sectional view of an example of holding a vibrating body of the motor of the embodiment.

FIG. 4 is a cross-sectional view showing a main part configuration of an ultrasonic motor according to a second embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a main part configuration of an ultrasonic motor according to a third embodiment of the present invention.

FIG. 6 is a front view of an elastic thin plate of the motor of the embodiment.

FIG. 7 is a cross-sectional view showing a main part configuration of an ultrasonic motor in a conventional example.

FIG. 8 is a cross-sectional view showing a contact state between a vibrating body of an ultrasonic motor and a moving body in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vibrating body 2 Elastic substrate 2a Projection body 3 Piezoelectric body 4 Moving body 5,6 Bearing 7 Rotating shaft 8 Coil spring 9 Felt 10 Support substrate 11 Housing 12 Elastic substrate 12a Projection body 13 Piezoelectric body 14 Vibrating body 15 Spherical projection 16 Support substrate 16a Tapered surface 17 Moving body 18 Rotating shaft 19, 20 Bearing 21 Coil spring 22 Housing 23 Elastic substrate 23a Projecting body 24 Piezoelectric body 25 Vibrating body 26 Supporting substrate 27 Spherical projection 28 Moving body 29 Rotating shaft 30, 31 Bearing 32 Coil spring 33 Housing 34 Elastic Substrate 34a Projection body 35 Piezoelectric body 36 Vibrating body 37 Hollow bush 38 Supporting substrate 39 Elastic thin plate 40 Moving body 41 Rotating shaft 42, 43 Bearing 44 Coil spring 45 Housing

Claims (3)

[Claims] 1. A moving body is brought into pressure contact with a vibrating body in which a piezoelectric body is coupled to an elastic substrate, and a traveling wave of flexural vibration is excited in the vibrating body, so that the vibrating body is moved between the vibrating body and the moving body. In an ultrasonic motor for moving the moving body via the frictional force of the circular concave surface which forms a spherical or conical projection at the center of the vibrating body and rotatably engages with the projection. An ultrasonic motor in which the vibrating body is held by a supporting substrate having. 2. A moving body is brought into pressure contact with a vibrating body in which a piezoelectric body is coupled to an elastic substrate, and a traveling wave of flexural vibration is excited in the vibrating body, so that the vibrating body is moved between the vibrating body and the moving body. In the ultrasonic motor for moving the moving body via the frictional force of the above, a spherical or conical projection that forms a circular concave surface at the center of the vibrating body and rotatably engages with the concave surface. An ultrasonic motor in which the vibrating body is held by a supporting substrate having. 3. A moving body is brought into pressure contact with a vibrating body in which a piezoelectric body is coupled to an elastic substrate, and a traveling wave of flexural vibration is excited in the vibrating body, whereby the vibrating body is moved between the vibrating body and the moving body. In an ultrasonic motor for moving the moving body through the frictional force of the ultrasonic motor, an ultrasonic motor in which a central portion of the vibrating body is rotatably engaged with and held by a support substrate by a thin elastic member.