Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Reexamination Certificate
1999-07-22
2001-10-09
Budd, Mark O. (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
C310S323020
Reexamination Certificate
active
06300705
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ultrasonic motor that is driven by elliptic vibration formed by combining longitudinal and twisting vibrations, and more particularly to an improved motor structure for converting the longitudinal vibration to the twisting vibration, or vice versa.
2. Description of Related Art
A standing-wave-type ultrasonic motor driven by elliptic vibration that is a compound of longitudinal and twisting vibrations is known. An example of this kind of motor is shown in FIG.
29
. The ultrasonic motor is composed of a stator
500
and a rotor
504
. The stator
500
includes a pair of metallic blocks
502
and
503
, between which a pair of piezoelectric elements
501
is interposed, constituting a Langevin-type vibrator. The metallic blocks
502
,
503
and the piezoelectric elements
501
are fastened together, thereby forming the stator
500
. The rotor
504
is mounted on the stator
500
by a through-bolt so that the rotor
504
silidably rotates on the upper surface of the stator
500
. Longitudinal vibration is generated by the piezoelectric elements, and a part thereof is converted into twisting vibration by slits
505
formed on the metallic block
503
. The longitudinal and the converted twisting vibrations are combined into elliptic vibration which appears on the upper surface of the metallic block
502
. The rotor
504
is driven by the elliptic vibration. The slits
505
are formed on the outer periphery of the metallic block
503
by machining with a certain depth. Conventionally, the slits
505
are machined with an end mill, a metal saw or the like. However, such machining is not easy, and it is expensive to machine all the slits on the outer periphery of the metallic block.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above-mentioned problem, and an object of the present invention is to provide an improved structure for converting the longitudinal vibration into the twisting vibration, or vice versa, and more particularly to provide a vibration converting member having plural slits which are formed without being machined. Another object of the present invention is to provide a method of manufacturing such vibration converting member.
The ultrasonic motor is composed of a stator and a rotor that slidably rotates on the stator. The ultrasonic motor is generally cylinder-shaped. The stator includes a vibration generating member in which ultrasonic longitudinal vibration is generated by piezoelectric elements and a vibration converting member that converts a part of the longitudinal vibration into twisting vibration. The vibration converting member has slits formed thereon by which the longitudinal vibration is converted into the twisting vibration. Both of the longitudinal and twisting vibrations are compounded into elliptic vibration in the stator, and the rotor is driven by the elliptic vibration.
The vibration converting member is formed by laminating a number of element plates each including cut-out portions to form the slits when laminated. Accordingly, the slits are easily formed on the vibration converting member without using a machining process. The element plates may be connected to one another by bonding their outer periphery with a bonding material such as solder or adhesive, or by covering the laminated block with molding resin or plating metal. Also, the element plates may be connected by press-fitting projections into holes formed on each element plate, or by a holding case that contains the laminated element plates therein. Preferably, the slits are slanted relative to the axis of the stator to enhance the efficiency for converting the longitudinal vibration into the twisting vibration. The slits may be open to the outer periphery or the center hole of the vibration converting member.
Alternatively, the vibration converting member is formed by combining several divided blocks made by die-casting, forging, sintering or the like. The slits are formed between the divided blocks when they are combined. The divided blocks are combined with one another by adhesive, for example.
The vibration converting member may be included in the rotor to form the compound elliptic vibration therein, or it may be formed in both of the rotor and stator to further enhance the conversion efficiency. The twisting vibration may be generated in the stator in place of the longitudinal vibration, and a part of the twisting vibration is converted into the longitudinal vibration to form the elliptic vibration.
Since the vibration converting member is made, according to the present invention, by laminating the element plates having cut-out portions or by combining the divided blocks, the slits are easily formed on the vibration converting member without using a machining process.
Other objects and features of the present invention will become more readily apparent from a better understanding of the preferred embodiments described below with reference to the following drawings.
REFERENCES:
patent: 4703214 (1987-10-01), Mishiro
patent: 5376858 (1994-12-01), Imabayashi et al.
patent: 5416375 (1995-05-01), Funakubo et al.
patent: 5825118 (1998-10-01), Okazaki
patent: 6018213 (2000-01-01), Yano
patent: A-7-184380 (1995-07-01), None
patent: A-7-75353 (1995-08-01), None
patent: A-9-182469 (1997-07-01), None
Komoda Masahiko
Tariki Atsushi
Asmo Co. Ltd.
Budd Mark O.
Fish & Richardson P.C.
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