Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Reexamination Certificate
1999-02-19
2001-02-27
Ramirez, Nestor (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
Reexamination Certificate
active
06194815
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to the generation of electrical energy, and particularly to a piezoelectric electric generator of the rotary type.
Piezoelectric electrical energy generators of the rotary type, e.g., comprising a rotating armature within a stator, are known and described, for example, in U.S. Pat. No. 3,101,420 (Hufferd, et al., Aug. 20, 1963), U.S. Pat. No. 3,208,443 (Hurwitz, Sep. 38, 1965) and U.S. Pat. No. 3,350,583 (Schiavone, Oct. 31, 1967) and in Soviet Union Patent 699,590 (Nov. 25, 1979), the subject matter of which U.S. patents is incorporated herein by reference.
The piezoelectric materials used in these patents are alternately mechanically strained and destrained for generating electrical energy. What occurs is that the mechanical strainings of the materials cause displacements of electrical charges within the materials. The charges resist such displacements, and the energy required to force the charge movement is stored in the form of electrical energy which can be extracted from the materials. In terms of efficiency, practically all the energy required to overcome the resistance by the charges to movement can be stored and recovered. However, the charges are embedded within piezoelectric host materials which themselves resist movement. The energy required to mechanically alternately strain and destrain the piezoelectric materials is generally quite significant, and to the extent that the energy required to mechanically strain and destrain the piezoelectric materials is not recovered, the efficiency of the mechanical energy to electrical energy conversion process is generally very low. The present invention addresses this problem.
SUMMARY OF THE INVENTION
In accordance with a first aspect of the invention, a piezoelectric generator comprises an outer support structure having a central axis, a centrally disposed hub, and means, e.g. a known eccentric mechanism, for causing the hub to circle, without rotation around its own axis, around the central axis of the support structure. A plurality of elastic piezoelectric elements are secured between the hub and respective spaced apart points on the outer support structure. Upon movement of the hub relative to the support structure, the elastic piezoelectric elements are alternately strained and destrained for generating electrical energy.
By using a number n of three or more symmetrically positioned, identical piezoelectric elements, which elements are identically strained, but 360
degrees out-of-phase with one another, practically all the energy required to initially mechanically strain the piezoelectric elements is recovered for successive strainings of the elements. Accordingly, substantially only that mechanical energy required for direct conversion into electrical energy is required during operation of the generator a for an exceptionally high efficiency of operation.
In accordance with a second aspect of the invention, two hubs are axially spaced apart along a driving shaft with the two hubs being equally eccentrically mounted on the shaft but 90 degrees out-of-phase with one another. Each hub contains one or more groups of piezoelectric elements with each group containing but two elements and with each group of two elements on one hub being matched (as hereinafter described) with a corresponding group of two elements in the other hub for the effective creation of a four element group of elements providing exceptionally high efficiency generator operation.
REFERENCES:
patent: 3030527 (1962-04-01), Czyryk et al.
patent: 3168660 (1965-02-01), Marks
patent: 3430080 (1969-02-01), Horan
patent: 4387318 (1983-06-01), Kolm et al.
patent: 0179584 (1988-07-01), None
Epstein, RPA Michael Y.
Medley Peter
Ocean Power Technology, Inc.
Ramirez Nestor
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