Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Patent
1988-10-24
1990-09-25
Budd, Mark O.
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
H01L 4108
Patent
active
049595806
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to piezoelectric devices and, more particularly, to piezoelectric motors.
2. Description of the Prior Art
Known in the art is a piezoelectric motor (GB,A, 2118374B), comprising a stator, a rotor frictionally interacting with the stator having a housing, a piezoelectric oscillator producing radial mode vibrations mounted on the housing and comprising a piezoelectric cell disposed coaxially with the rotor and made in the form of a disk with electrodes, the disk being polarized perpendicular to the electrodes, and at least two pushers, each pusher having one end secured on the cylindrical surface of the piezoelectric cell and another end resting against the rotor.
In this piezoelectric motor any change of the rotational speed can be effected only by changing the diameter of the piezoelectric cell. This does not allow one to make a general-purpose piezoelectric cell suitable for any rotational speed of the rotor of the piezoelectric cell suitable for any rotational speed of the rotor of the piezoelectric motor. Therefore, the range of rotational speeds of the rotor for a given piezoelectric cell is limited.
Furthermore, the robustness of the pusher increases with the increase in the thickness of the piezoelectric cell and this does not allow one to reduce the input power, for example, when running the piezoelectric motor under a low load, e.g. for driving the diaphragm of a photographic camera.
SUMMARY OF THE INVENTION
The basic object of the invention is to provide a piezoelectric motor having a design which permits the axis of symmetry of each pusher to be displaced so that it becomes parallel to the axis of symmetry of the piezoelectric cell by converting the radial acoustic vibrations in the piezoelectric cell into transverse vibrations and then into longitudinal acoustic vibrations in the pushers of the piezoelectric radial mode oscillator. This widens the range of rotational speeds of the rotor for a given piezoelectric cell and the range of input power of the motor.
This object is attained by providing a piezoelectric motor comprising a stator, a rotor frictionally interacting with the stator, having a housing, a piezoelectric oscillator producing radial mode vibrations mounted on the housing and comprising a piezoelectric cell disposed coaxially to the rotor and made in the form of a disk with electrodes, the disk being polarized perpendicular to the electrodes, and at least two pushers, each of which has one end secured on the piezoelectric cell and has another end resting against the rotor. According to the invention, one end of each pusher is secured on at least one flat surface of the piezoelectric cell so that a gap is provided between the piezoelectric cell and the pusher.
This invention makes it possible to produce a number of piezoelectric motors featuring a wide range of input power.
The present invention also makes it possible to produce piezoelectric motors with general-purpose piezoelectric cells featuring a wide range of rotational speeds of the rotor and a wide range of input power. The invention allows one to reduce the cost of a piezoelectric motor so that it can be used as an actuating drive instead of electric magnets, and also to reduce the labour consumption in manufacture of piezoelectric motors.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is further described by way of example with reference to the accompanying drawings, in which:
FIG. 1 is a longitudinal sectional view of a piezoelectric motor featuring a cylindrical rotor encompassing pushers pressed thereto, according to the invention;
FIG. 2 shows a view taken along the line II--II of FIG. 1;
FIGS. 3a, 3b, 3c show a piezoelectric cell carrying pushers secured thereon for the piezoelectric motor having a rotor encompassing the pushers;
FIGS. 3d, 3e, 3g show a piezoelectric cell carrying pushers secured thereon for a piezoelectric motor having a rotor disposed between the pushers;
FIG. 4 is a schematic view of a piezoelectric motor, in
REFERENCES:
patent: 3211931 (1965-10-01), Tehon
patent: 4400641 (1983-08-01), Vishnevsky et al.
patent: 4453103 (1984-06-01), Vishnevsky et al.
Lavrinenko Vyacheslav V.
Vishnevsky Vladimir S.
Budd Mark O.
Kievsky Politekhnichesky Institut Imeni
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