WO2009125429A2

WO2009125429A2 - Double acting power take off for ocean wave energy converter

Info

Publication number: WO2009125429A2
Application number: PCT/IN2009/000132
Authority: WO
Inventors: Arunachalam Amar Karthik; Sri Hari Raju Katari
Original assignee: Arunachalam Amar Karthik; Sri Hari Raju Katari
Priority date: 2008-03-20
Filing date: 2009-03-02
Publication date: 2009-10-15
Also published as: WO2009125429A3

Abstract

The proposed invention captures and converts the energy available in ocean waves into any usable form of energy. To complete the conversion the entire system works in two stages, the first stage captures up and down motion of wave surface into alternative mechanical rotation and the second converts this alternative rotation into continuous rotation with no significant loss in transmitted energy. This captured and converted energy in the form of mechanical rotation could be used for further utilization. The wave harnessing is done in first stage which comprising a Central Body (1) and balancing weight (2) assembly which oscillates along up and down motion of waves and produces an alternative mechanical rotation at the input shaft (3). The second stage of conversion is responsible for converting captured energy in the form of alternative rotation at shaft (3) into continuous rotation by a unique gearbox called Unidirectional Gearbox. This unidirectional gearbox is capable of converting any clockwise or anti-clockwise directional rotation at its input shaft into continuous unidirectional rotation at its output shaft. This process happens with no significant energy loss. In the over all assembly, the central body assembly is coupled with a shaft (3) and this shaft is coupled with the input shaft of said unidirectional gearbox. The output (Continuous unidirectional rotation) of the Unidirectional Gearbox could be utilized for any purpose; in this case the output shaft is connected with an electric generator.

Description

"DOUBLE ACTING POWER TAKE OFF FOR OCEAN WAVE ENERGY CONVERTER"

The following specification particularly describes the invention and the manner in which it is to be performed. TECHNICAL FIELD OF THE INVENTION

This invention relates to a buoyant body (Called as Central Body from herein) assembly and a gearbox for harnessing both up and down movement of ocean waves to produce continuous mechanical rotation for further energy conversion thereof.

BACKGROUND OF THE INVENTION AND PRIOR ART

Open ocean swells contain large amounts of energy which can be utilized as an alternative source of electric power. This type of energy source does not create pollution or depend on finite resources. In the past, a variety of systems have been utilized to generate electric power from ocean swells by converting the motion of the waves to some other form of energy to turn a conventional rotating generator. This type of system can be seen in prior systems which use wave motion to drive a hydraulic pump to force a fluid through a turbine connected to an electrical generator. Other ocean energy systems use wave motion to force air through hollow shafts.

Certain types of conversion plants use floats or buoyant pontoons as their means for capturing ocean-wave energy. The floats, placed in the ocean, undulate with the waves. The mechanical energy captured by the floats is imparted to some form of mechanical to electrical energy conversion mechanism. It is self apparent that the better the performance of the float in terms of capturing the available wave energy, the more the mechanical energy that can be imparted to the conversion mechanism. In turn this leads to an increased electrical output.

By way of background information to the invention disclosed herein, the energy component contained within a typical ocean wave is now explained. The wave can be split into two components. These are known as wave trough and wave crest. The wave crest is responsible for lifting the float and the trough is responsible for lowering the float. The available energy is divided equally between these two parts of the wave.

To date, accepted teaching states that the maximum energy that can theoretically be captured by a float is limited to the 50% of the available wave energy. This is would be obvious from the following explanation.

When the wave passes; the wave crest lifts the float up due to the buoyancy force and the wave energy is intern transferred to the pivoted point of the connecting rod. At the time when wave trough approaches, the water level beneath the float goes down and the float supposes to follow the water level by using its own weight. A heavy dead weight or spring action is needed for the float if it is needed to harness energy even during the down fall. When the dead weight is added, the equivalent amount of wave energy is lost during the lifting action since the weight is acting against the wave crest. This reason makes any wave energy converter to be less efficient in hydraulic efficiency and intern in overall efficiency. In order to avoid the energy loss due to own weight of the float body and to improve the over all efficiency of Wave Energy Conversion the below described invention is made. Before entering in to the detailed description it is important to import the knowledge of previous publications and patents which comes similar to the scope of the proposed invention. The following are a few inventions related to the proposed invention.

US 6389810 (2002-05-21)

A device to convert vertical motion of waves in a body of water into useable work has hollow float centrally mounted on vertical sleeve sliding on fixed vertical shaft. Oscillations are converted into rotation via an opposing pair of pinion gears, transferring power from upstroke and downstroke respectively, by meshing with circular grooves on sleeve. The device is protected from lateral and torsional forces of the waves by an encircling slotted wall. The float may be half filled with water to balance buoyancy and gravitational forces.

WIPO Publication Number WO2008129378 (A2)

The invention has a float of any form, preferably in the form of long sealed and rigid container/tube, floating upright and occupying down to a square foot or less than sea surface area. The float has three parts or chambers; the smaller top part/chamber, is filled with any heavy material, preferably sea water, the middle chamber is larger and is filled with air or any floating materials and the largest, third bottom part/chamber of the tube/container is filled with any heavy material, sea water preferably. The shape and distribution of the content of the float is so arranged to make it possible for a heavy float occupy a smallest surface area. The ratchet wheel's teeth being very close, a smallest movement of the float, will pull on the ratchet wheel, and activate the pawl and maintain a rotation of the driving wheel. Through the driving wheel the energy is further transferred and converted.

WIPO Publication Number WO 2008103344 (A2) (2008-08-28)

An ocean wave driven energy device that uses the power of ocean waves to continually lift and lower a float which in turn lifts or lowers one side of a lever arm about a stationary pivot point thereby driving down or raising a piston, which is attached to the opposite side of the lever arm, thru a cylinder which in turn causes large volumes of air to move. That air is funneled to drive turbines which produce electric power.

WIPO Publication Number WO 2007042800 (Al) (2007-04-19)

A float for use in capturing energy from waves, said float comprising: a central body providing buoyancy, said float further comprising: a leading part which has a leading surface which, in use of the float, is inclined upwards from horizontal such that the top of said leading surface projects further from said central body than the bottom of said leading surface and/or a trailing part which, in use of said float, extends downwards from said central body and presents a trailing surface which is inclined downwards from horizontal such that the top of said trailing surface is closer to said body than the bottom of said trailing surface.

US 2007108773 (Al) (2007-05-17)

A wave power apparatus includes a plurality of rotationally supported arms, each of which carries a float at its free end, so that a translational movement of the float caused by a wave results in rotation of the arm. The apparatus comprises power conversion means for converting power transmitted from the wave to the arms into electric power, e.g. a hydraulic system, in which a hydraulic fluid is displaced by the movement of the arms to drive one or more hydraulic motors. The plurality of are arranged in a row such that a wave passing the row of arms causes the arms to successively pivot with a mutual phase shift. Thereby, an even power output may be achieved, and the need for frequency converters may be reduced or eliminated.; Preferably, each arm is connected to a hydraulic cylinder of the hydraulic system, whereby a plurality of arms feed hydraulic medium into the hydraulic motor or motors through common hydraulic conduits.

US 2008169653 (Al) 2008-07-17

A device comprising a pivoting float and lever arm combination attached to a beam such that the float and lever arm can unfold and change orientation to the ocean surface. The float and lever arm pivot and the float can be rotated to a vertical position relative to the water surface. The lever arm can, for example, be attached to a suspended beam or to the ocean bottom. A method for moving a float and a lever arm in response to ocean wave action comprising pivotally attaching a first end of a lever arm to a float; attaching a second end of the lever arm to a connector component; and attaching an end of the connector component to the ocean floor.

WIPO Publication Number WO2008129378 (A2) (2008-10-30)

A tide and wave concertina energy conversion device, small and portable or huge and fixed, that can be used at most locations on sea or lakes, including any form, preferably, an elongated tubular form container, filled and sealed with any material, preferably with water, as float , on down to a square foot or less water surface area, connected to two concertina devices and which convert the movement of float, by the rise and fall of the tide and wave, into a unidirectional rotary motion of an only driving wheel , which turns generator or other power output via belt.

OBJECTS OF THE INVENTION

A primary objective of the present invention is to provide an apparatus and a method for effectively convert up and down motion of ocean waves into alternative rotation of a shaft.

Another object of the present invention is to provide an apparatus and a method for converting up and down motion of ocean waves into alternative mechanical rotation by eliminating the energy conversion losses due to the self weight of the float or buoyancy material assembly.

Another object of the present invention is to provide an apparatus and method for converting up and down motion of the ocean waves into alternative mechanical rotation by using gravity force.

It is also an objective of converting alternative mechanical rotation into continuous rotation without any further significant energy loss by a special type gearbox.

Reference may be made to principal claims indicating inventive steps/features of the present invention and subsequent claims indicating advantageous features of the present invention.

SUMMARY OF THE INVENTION

It is therefore among the principal objects of the present invention to provide a means of capture both up and down motion of waves to the maximum extend and to convert said captured alternative mechanical rotation into continuous rotation so that the retrieval of energy from ocean waves is substantially increased. The present invention provides a float assembly and a Gearbox Assembly which comprising: a central body(l) with the density more than surrounding water, said float assembly further comprising: a connecting rod(4) with sufficient length and pivoted(3) rigidly connected with a shaft(7) preferably at the middle, balancing weight(2) to mount at one end of said connecting rod and finally a Gearbox which gives a continuous rotation at its output shaft by utilizing and converting alternative mechanical rotation given at its input shaft.

According to the invention, the wave energy is harnessed and converted into usable form in two major stages. The first stage is in float assembly and the second is in unidirectional gearbox. The Working, Uniqueness and construction of each stage will be apparent from the following explanation.

a float assembly to be fitted with any wave energy converter for use in ocean waves for capturing the energy thereof comprises as a first part, a central body (1) which is a solid body with any shape (Preferably Cylindrical shape), volume and the density more than the surrounding water body, and as a second part the connecting rod (4) connected with said central body (1) by one of its end and said balancing weight (2) at its other end. The said balancing weight is to be decided to make sure at least one half of the central body's volume comes out of the water body when the whole assembly is installed in the ocean. The connecting rod is rigidly fixed with a shaft (3) and said shaft is supported by bearings. The Axis of the shaft is kept perpendicular to the connecting rod axis.

The Unidirectional Gearbox for converting alternative mechanical rotation into continuous rotation with no significant energy loss comprises as a first part, two one-way gear wheels or free wheel gears (10 & 11) mounted on a shaft (3) wherein one gearwheel (10) will transfer energy when the shaft (3) rotates in clock wise and will overrun or disengage during the counter clockwise rotation of the shaft (3), the second wheel will transfer energy when the shaft (3) rotates in counter clock wise and will overrun or disengage during the clockwise rotation of the shaft (3), and as a second part two main gear wheels (14 & 15) connected through a bearing supported shaft and a gear wheel with each of said one-way gear wheels 10 and 11 respectively. Another gearwheel is geared with any of the said main gears (14 & 15) to transfer mechanical energy for further conversion.

The entire assembly of unidirectional gearbox is kept inside an airtight box called main box (6). This main box (6) is securely mounted in Ocean and kept well above the maximum tide level on a fixed pillar (7) or a platform.

BRIEF DESCRIPTION OF THE DRAWING

Further objects and advantages of this invention will be more apparent from the ensuing description when read in conjunction with the accompanying drawings and wherein: FIG. 1 is a schematic view, in perspective of an embodiment of the invention. FIG.2 is a schematic Top view of an embodiment of the invention. FIG.3 is an Isometric view of overall assembly of the invention.

DETAILED DESCRIPTION OF THE DISCLOSED EMBODIMENT

The method of operation of the float assembly and Unidirectional gearbox is as follows. Float Assembly:

The entire assembly of connecting rod, counter weight and the central body is to be fitted with a wave energy conversion device.

The connecting rod is pivoted preferably at its middle with a shaft (7) which is mounted by a bearing (6) assembly. This shaft (7) is rigidly connected with the connecting rod (4). For efficient use, the shaft (7) axis is to be kept perpendicular to the connecting rod (4) and substantially parallel to the ocean surface (5). This assembly makes sure that the shaft gives alternative rotation when one end of the connecting rod oscillates with respect to the pivoted point. The said shaft is to be connected or mounted on any wave energy conversion device for further utilization and conversion of converted mechanical energy. The said central body (2) is rigidly connected with one end of said connecting rod (4) with connecting means. The said balancing weight (2) is rigidly connected with another end of said connecting rod.

This entire float assembly works as follows

Once the Float assembly is fitted with the Wave Energy Converter the entire assembly is to be placed in the ocean such that the central body partially dips into the water surface. The balancing weight will make the connecting rod to pull at least one half of the central body to come out of the water surface. When the assembly is installed the force due to the gravity of balancing weight and the central body gets equal and the connecting rod maintained in equilibrium state. This assembly makes the following action to happen.

When the wave passes, the effective weight of the central body (1) gets reduced due to the buoyancy force by the increase in water level by wave crest at central body area, intern balancing weight (2) pulls the central body up and makes the connecting rod to oscillate with respect to the pivoted point (3) and this makes the shaft (7) to rotate in one direction, the central body's effective weight gets increased due to gravity when the water level decreases during the wave trough and intern the central body pulls the balancing weight up and makes the connecting rod to oscillate with respect to the pivoted point (3) and this makes the shaft (7) to rotate in another direction. These said reactions give continuous oscillation for ^• the assembly with respect to the pivoted point of the connecting rod and produces alternating rotation at said shaft and thus the wave energy is harnessed and transferred for further conversion.

Unidirectional Gearbox Assembly

The following action makes the entire assembly of gears and free wheels to convert alternative rotation at the input shaft (3) into continuous unidirectional rotation at the output gear (16) with no significant energy loss. When the shaft (3) rotated in clockwise by the float assembly, the free wheel gear (10) gets encaged with the shaft (3) and rotates the main wheel (14) in counter clockwise through the gearwheel 13 and intern the output wheel (16) rotates in clockwise. When the shaft (3) rotated in counter clockwise by the float assembly, the free wheel gear (11) gets encaged with the shaft (3) and rotates the main wheel (15) in clockwise through the gear wheel (12) and intern the output wheel (16) rotates in clockwise through the main wheel (14). In both the above cases the output wheel (16) rotates in clockwise direction this action makes the gearbox to produce continuous rotation at its output wheel (16) from the alternative rotation given at the input shaft (3) by central body assembly.

Claims

I CLAIM:

1. A Double Acting Power Takeoff apparatus that converts up and down motion of water waves into continuous rotation comprising:

At least one arm or connecting rod supported at its m iddle by a bearing supported shaft.

A central body rigidly connected at one end of said connecting rod and this end of connecting rod is called as central body end.

A balancing weight attached with the other end of said connecting rod, which is opposite to the central body end.

A unidirectional gearbox coupled with the connecting rod shaft, to convert alternative rotation of said shaft into continuous rotary output with no significant power loss.

2. A Double Acting Power Takeoff apparatus according to claim 1, wherein the connecting rod is rigidly fixed with a bearing supported shaft which is secured on a fixed position relative to the ocean surface on a platform in the ocean and said shaft is coupled with said unidirectional gearbox.

3. A Double Acting Power Takeoff apparatus according to claim 1, wherein the central body is a solid object with any shape and volume with density equal or more than the surrounding water body.

4. A Double Acting Power Takeoff apparatus according to claim 3, wherein the shape of the central body is preferably cylindrical and the maximum outer dimensions of the central body is less than l/4^th of the wave length of the respective ocean surface where the invention is installed.

5. A Double Acting Power Takeoff apparatus according to claim 13, wherein the shaft (3) is fitted with two one way clutch (OWC) gears (10,11) at its free end wherein one OWC gear transmits energy-during clockwise rotation of said shaft (3) and the second OWC gear transmits energy during counter clockwise rotation of the shaft(3).

6. A Double Acting Power Takeoff apparatus according to claim 18, wherein one gear wheel called Main Wheel 1 (MWl) (14) is geared with any one of said OWC gear through a bearing supported shaft and gear (13), an another gear wheel called Main Wheel 2 (M W2) (1_.5) is geared with remaining OWC gear through a bearing supported shaft and gear (12), both the main wheels are mutually geared together wherein an output gearwheel is geared with any of said main wheels for further energy conversion.

7. A Double Acting Power Takeoff apparatus according to claim 1, wherein the entire gear assembly is kept in an airtight chamber or box called Mainbox (6) which is placed on a platform in the ocean above the maximum ocean surface. Wherein the connecting rod end of said shaft (3) is kept outside the Mainbox

(6).

8. A Double Acting Power Takeoff apparatus according to claim 7, wherein said Wave Energy Converter is to be placed in the ocean above the ocean surface on a platform with said central body partially submerged into the ocean surface and the balancing weight is attached with another end of said connecting rod (4) to bring at least one half of the central body out of the water surface.

9. A Double Acting Power Takeoff apparatus herein substantially described with reference to and as illustrated through accompanying drawing. These drawing are for illustrative purpose only not intended to limit the scope of the invention.