Piezoelectric electric energy generator

• US 5,512,795 A
• Filed: 03/13/1995
• Issued: 04/30/1996
• Est. Priority Date: 03/13/1995
• Status: Expired due to Term

• Current Assignee: Ocean Power Technologies, Inc.
• Original Assignee: Ocean Power Technologies, Inc.
• Inventors: Epstein, Michael Y., Carroll, Charles B.
• Primary Examiner(s): Dougherty, Thomas M.
• Application Number:
  US08/404,180
• Time in Patent Office: 414 Days
• Field of Search: 310/338, 310/339
• US Class Current: 310/339
• CPC Class Codes: H02N 2/18 producing electrical output from mechanical input, e.g. generators for measurement devices G01

Abstract

An electrical energy generator comprises a cylindrical stator, a cylindrical liner of a piezoelectric material in concentric contact with the stator, and an armature rotatable about the liner. In one embodiment, as the armature rotates, the armature squeezes successive portions of the liner against the stator for alternately compressing and decompressing the liner portions for causing them to generate electrical energy. In another embodiment, the armature causes alternating stretching and destretching of successive portions of the liner between spaced apart portions of the stator for causing the liner portions to generate electricity.

Claims

1. A piezoelectric generator comprising a first member, a second member of piezoelectric material disposed along said first member, an armature movable relative to second member for alternately straining and destraining adjacently disposed portions of said second member in response to said adjacently disposed portions of said second member being successively compressed and decompressed between said armature and said first member, said first member comprising a portion of a circular cylinder, said second member comprising a uniformly thick layer of said piezoelectric material disposed in contact with said first member, and said armature comprising a member rotatable about an axis of revolution of said first member, said first member and said armature comprising electrically conductive materials which are rigid in comparison with said piezoelectric material, and said first member and said armature each comprising an electrode for contact with a respective one of oppositely disposed surfaces of said piezoelectric material layer for collecting electrical energy in response to said alternating straining and destraining thereof.

2. A generator according to claim 1 wherein one of said electrodes is segmented into spaced apart electrode portions electrically insulated from one another along said one surface contacted by said one electrode.

3. A generator according to claim 2 wherein said armature includes a shaft rotatable about said axis, an arm mounted on said shaft and extending radially therefrom, and a roller mounted on said arm for rotation abut a roller axis parallel to said shaft axis, and said roller having a peripheral surface engaging said second member.

4. A generator according to claim 3 including means for rotating said shaft about said axis for providing said relative movement between said armature and said second member.

5. A generator according to claim 4 wherein said rotating means comprises a pendulum suspended from said shaft.

6. A generator according to claim 5 wherein, in use of said generator, said pendulum swings through an arc of less than 360 degrees, and said layer of piezoelectric material is disposed along a portion of a cylindrical surface of said first member having an angular length less than 360 degrees.

7. A generator according to claim 6 wherein said first member comprises a hollow, circular cylinder, and said cylindrical surface comprises an interior surface of said cylinder.

8. A piezoelectric generator comprising a first member, a second member of piezoelectric material disposed along said first member, an armature moveable relative to said second member for alternately straining and destraining adjacently disposed portions of said second member in response to said adjacently disposed portions of said second member being successively stretched and destretched between portions of said first member by contact of said armature with said adjacently disposed second member portions, said first member having a surface including a plurality of spaced apart raised portions alternating with a plurality of depressed portions, said second member being stretched in tension relative to said first member for contacting said raised portions and being spaced above said depressed portions, and said armature being spring biased for pressing successive portions of said second member extending between adjacent raised portions downwardly relative to said adjacent raised portions in response to movement of said armature relative to said second member, and electrodes connected to said second member for collecting electrical energy in response to said alternating straining and destraining thereof.