Wave operated electrical generation system

• US 4,260,901 A
• Filed: 02/26/1979
• Issued: 04/07/1981
• Est. Priority Date: 02/26/1979
• Status: Expired due to Term

• Current Assignee: David D. Woodbridge
• Original Assignee: David D. Woodbridge
• Inventors: Woodbridge, David D.
• Primary Examiner(s): Truhe, J. V.
• Assistant Examiner(s): Duncanson, Jr., W. E.
• Application Number:
  US06/015,242
• Time in Patent Office: 771 Days
• Field of Search: 290/42, 290/53, 417/330-337, 417/341, 417/343
• US Class Current: 290/42
• CPC Class Codes: F03B 13/1855 where the connection between wom and conversion system takes tension and compression F03B13/187, F03B13/1875 take precedence
• CPC Class Codes: F05B 2220/707 of the linear type
• CPC Class Codes: Y02E 10/30 Energy from the sea, e.g. using wave energy or salinity gradient

Abstract

A system for converting the mechanical energy in the wave motion of a body of water into electrical energy. A frame is fixed with respect to the wave motion of the water. A flotation element is buoyantly supported by the water and constrained to follow only the vertical component of the wave motion. The motion of the flotation element is transferred to an electrical generating device which includes a device for producing electromagnetic flux and electrical coils. The motion of the flotation element causes relative motion between the flux-producing device and the electrical coils thereby generating an electromotive force. A positioning subsystem is provided for moving the electrical generating device relative to the flotation element when the average depth of the body of water changes so as to maintain a symmetrical relative motion between the flux-producing device and the electrical coils.

Claims

1. A system for converting the mechanical energy in the wave motion of a body of water into electrical energy comprising in combination:

a frame being fixed with respect to said wave motion of said water;

flotation means buoyantly supported by said water, for following said wave motion;

a subframe attached to said frame and movable in the vertical plane with respect thereto;

a first pivot shaft supported by said subframe;

a pivot arm attached to said flotation means, with said pivot arm rotatable about said first pivot shaft;

means including means for generating magnetic flux and electrical conductor means coupled to said subframe and said pivot arm for generating electrical voltages from the relative motion therebetween, said magnetic flux means comprising at least one magnet having a pair of poles, and said electrical conductor means comprises a pair of essentially cylindrical coils of electrically conducting cable, each of said coils having a cylindrical coaxial void therethrough, said coils being arranged such that one pole of said magnet is penetrating the void of one of said coils while the other pole of said magnet is withdrawing from the void of the other one of said coils;

voltage comparison means connected to said pair of coils for producing a control signal when the voltages across said pair of coils are not equal; and

subframe positioning means connected to said subframe and to said voltage comparison means, said positioning means responsive to such control signal for vertically positioning said subframe relative to said flotation means so as to produce essentially equal electrical energy from each one of said pair of coils.

2. A device for generating an electromotive force by utilizing the wave motion on the surface of a body of water, comprising in combination:

a frame fixed with respect to the wave motion of the surface of the water;

flotation means buoyantly supported by the water near the surface thereof for following the wave motion of the surface;

a pivot shaft supported by said frame;

a pivot arm disposed on said pivot shaft having a first end pivotally coupled to said flotation means and a second end adapted to move in an arcuate path in response to vertical movement of said flotation means;

a pair of electrical coils, each having an arcuate clyindrical void therethrough, said pair of coils mounted to said frame with the arcuate axes of said voids forming an arc and with an angular separation therebetween preselected to be proportional to the expected difference between the height of a wave crest and the depth of a wave trough on the surface of the water;

an arcuate magnetic flux producing means symmetrically attached to said second end of said pivot arm between said pair of coils matching and aligned with said arcuate axis and in position to cause a first pole of said magnetic flux producing means to penetrate through the void of one coil of said pair when said flotation means is at the crest of a wave and to cause a second pole of said magnetic flux producing means to penetrate through the void of the other coil of said pair when said flotation means is at the trough of a wave, said magnetic flux producing means and said coils being arranged such that one pole of said magnetic flux producing means is penetrating said void of one of said pair while the other pole of said magnetic flux producing means is withdrawing from said void of the other one of said pair; and

control means controlling said magnetic flux producing means and said coils relative to the average depth of the water such that the arcuate movement of said magnetic flux producing means is symmetrical with respect to said voids of said coils.

3. The device as described in claim 2 in which said magnetic flux producing means is a bar type magnet.

4. The device as described in claim 2 in which said magnetic flux producing means is an electromagnet.

5. The device as described in claim 2 in which said flotation means includes a vertical shaft having bearing means attached to said frame for constraining said flotation means to move only in a vertical direction.

6. The device as described in claim 2 which further comprises vertical controlling means for controlling said flotation means to follow only the vertical component of the wave motion of the surface of the water.

7. The device as described in claim 6 in which said vertical controlling means comprises a shield attached to said frame and surrounding said flotation means for shielding said flotation means from any horizontal component of the wave motion of the surface of the water.

8. The device as described in claim 2 in which said control means comprises:

a vertically movable portion of said frame having said pivot means and said pair of electrical coils supported thereon;

drive means for moving said movable portion vertically;

average water level sensing means for producing a control signal when a change occurs in the average depth of the body of water; and

drive control means responsive to such signal for energizing said drive means to move said movable portion in a direction for a distance essentially equal to the change in average depth of the body of water.

9. The device as defined in claim 8 in which said water level sensing means includes comparator means for comparing the output voltage produced by one of said coils to the output voltage produced by the other of said coils in response to the movement of said flux producing means through said void of said coils, and said drive control means is connected to said comparator means adapted to energize said drive means in response to such signal to move said movable portion of said frame in a direction and for a distance to equalize the voltages across said pair of coils.

10. The device as defined in claim 9 in which said drive means is a reversible electrical motor adapted to move said movable portion of said frame in either the up or down direction.