FIELD OF THE INVENTION

The present invention relates to a wind turbine for generating electricity by means of roller driven mechanical power transmission. BACKGROUND OF THE INVENTION

Wind turbine convert kinetic energy of the wind to rotational mechanical energy. There are multiple systems are available to convert this energy to the generator.

• Direct drive by coupling rotor to motor shaft

• Gear box and

· Chain drive

DIRECT DRIVE:

A direct drive mechanism is one that takes the power coming from a motor without any reductions. But the problem with direct drive in VAWT is the RPM difference. Since the motor/generator needed very higher angular velocity when compared to the turbine rotor.

GEAR BOX

Gear box is a mechanical system that uses gears and gear trains to provide speed and torque conversions from a rotating power source to another device.

CHAIN DRIVE

Chain drive is another way of transmitting mechanical power from one place to another. It uses a calculated sprocket wheel to match required gear ratio. The sprocket wheel acts as a driver which directly coupled to the turbine rotor.

The both gear box and chain drive needs frequent maintenance/lubrication. So, there is a need for a transmission mechanism to eliminate the need of such arrangements.

In industries cold-rolling is a process which has long been known for the shaping of continuously moving strip, profiled section or sheet made from steel or other metals. The rolling strip passes between oppositely revolving rollers in order to undergo a shape/dimension change. Here, the movement of the rolling strip is achieved by set of oppositely revolving rollers, which provide predetermined contact pressure on the rolling strip for moving and embossing design. The arrangement is illustrated in figure 1.

The prior art US 6874344 B1 relates to a method for cold-rolling metallic rolling stock (4), in which the rolling stock (4) passes through the roll nip (3) between oppositely driven rollers (2) at room temperature in order to undergo a plastic shape change. We can understand from the above description, the movement of the rolling stock strip is achieved by passing the rolling stock/disc/strip between oppositely driven rollers with predetermined pressure. But this entire process is meant for linear motion of the strip. The reverse principle of above said cold rolling is implemented in our present invention for mechanical power transmission. With a circular strip, the profile of the strip and the rollers are changed to accommodate the differential linear speed between the outer and inner surfaces.

In cold rolling: Rolling stock/strip is moved between oppositely rotating rollers for changing shape. Here, the oppositely rotating rollers are act like a "driving" or drive means, which is the source of action or movement. The rolling stock is act like a driven means is turned or moved by the drive means (Refer fig 1 ).

Proposed concept: A circular ring is moved between oppositely rotating rollers for power transmission from disc of rotor assembly to rollers of generator assembly. Here, disc is act like a "driving" or drive means, which is the source of action or movement. The oppositely rotating rollers are act like a driven means is rotated or moved by the disc/drive means. (Refer fig 2,2a).

OBJECT OF THE INVENTION

The object of the present invention is to provide an efficient transmission means in vertical axis wind turbine to eliminate existing chain drive mechanism and lubricant system.

Another object of the invention is to obtain optimum power transmission by reversely implement the principle of cold rolling technique as a power transmission mechanism in wind turbine. Yet another object of the invention is to acquire optimum power from main disc rotation of rotor assembly by providing predetermined favourable contact pressure through rollers.

Yet another object of the invention is to allow power generation through plurality of generators at a same time.

Yet another object of the invention is to improve the stability and bring down CG of the turbine by connecting the main discs with rotor assembly through flexible connection. Yet another object of the invention is to generate power even any one generator failure condition.

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Yet another object of the present invention is to eliminate differential or variable slip along the line of contact.

Yet another object of the invention is to provide tapered profile structure on both the main driving 75 means and driven means for matching both main driving means and plurality of driven means, maintaining relative speed and eliminating variable/differential slip along the line of contact.

Yet another object of the invention is to obtain/achieve relative speed between roller driven transmission means by matching the both line of contact region of tapered main driving means and 80 tapered rolling means

Yet another object of the invention is to control/minimize the slip level by maintaining the contact pressure ratio within the predetermined limit between the main driving means and driven means.

85 Yet another object of the invention is to provide matching tapered rollers arrangements for both Horizontal axis wind turbine as well as Vertical axis wind turbine for eliminating the need of gear box transmission system.

Further object of the invention is to replace large gear box assembly and single large generator in both 90 vertical axis wind turbine as well as horizontal axis wind turbine.

SUMMARY OF THE INVENTION

The present invention relates to a wind turbine for generating electricity by using unique way of transmission mechanism. The transmission mechanism is derived from reverse principle of cold rolling 95 mechanism. The implantation of unique method will improve power transmission performance/efficiency of the wind turbine. In cold rolling oppositely rotating rollers are act like a driving or drive means, which is the source of action or movement. The rolling strip/sheet is act like a driven means is moved by the driven means/oppositely rotating rollers. In our present invention the oppositely rotating rollers (R1&R2) are act like a driven means is rotated or moved by the main disc/drive means (D). The main driving 100 means is connected with rotor assembly through flexible means for bringing down CG of the turbine and obtaining high turbine dynamic/static stability. Further, the engagement region or line of contact of main driving means and plurality driving means are having a tapered shape to eliminate differential/variable slip along the line of contact and obtain relative speed during power transmission.

BRIEF DESCRIPTION OF DRAWINGS

Fig 1 illustrates the prior art of cold rolling's principle of working, which shows oppositely rotating rollers are act like a driving or drive means, which is the source of action or movement. The rolling strip/sheet is act like a driven means is turned or moved by the driven means/oppositely rotating rollers.

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Fig 2 and 2a illustrates embodiment of the present invention, which shows oppositely rotating rollers (R1 &R2) are act like a driven means is rotated or moved by the main disc/drive means (D).

Fig 3a&3b illustrates one of the embodiments of the invention which shows the matching tapered 115 contact points (X, Y with P, Q) of tapered main driving means (D) and tapered driven means (R).

Where, X and Y are respectively arranged R, and R _n radius from centre rotating axis of the turbine. P and Q are arranged n or DJ2 and r _n or D _n /2 radius from the centre rotating axis of the generator.

Fig 4a & 4b illustrates another embodiment of the invention which shows position of tapered driving 120 means on the flat main driving means (D), where generator assembly is correspondingly tilted / positioned along with driving means (R) to accommodate with flat shape of the main driving means (D).

Fig 5 illustrates resultant chart. Which clearly shows, how the required contact pressure is experimentally derived.

125 The above drawing illustrates the details has been given and will be provided with respect to certain specific embodiments, it is to be understood that the scope of the disclosure should not be limited to such embodiments but that the same are provided simply for enablement and best mode purposes. The breadth and spirit of the present disclosure is broader than the embodiments specifically disclosed 130 and encompassed within the claims eventually appended hereto.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a wind turbine, more particularly the invention relates to a unique power transmission assembly which is derived from reverse principle of cold rolling technology.

135

One of the embodiment of the invention discloses about a wind turbine for generating electricity by means of power transmission means which includes main driving means (D) and plurality of pair of oppositely rotating driven means (R1 , R2), the said wind turbine comprises of a tower assembly, a rotor assembly rotatably secured on the tower assembly with air foil blade arrangements. A power

140 transmission means configured to transmit the torque of rotor assembly to generator (G1 ,G2) for generating electricity, the said power transmission means includes at least one main driving means (D) which is flexibly connected with rotor assembly and plurality of pair of driven means (R1.R2) which is rotatably engaged with the main driving means (D), the said main driving means (D) configured to move through plurality of said driven means (R1.R2) for transmitting rotating torque to each driven means

145 (R1.R2). Each said driven means configured to attach with shaft (S) of generator for generating electricity, each said driven means (R) with generator(G) assembly configured to provide predetermined favourable pressure on the main driving means (D) to acquire optimum power, Wherein, when the wind turbine obtain cut in wind speed then the main driving means (D) moves through plurality of driven means (R1.R2) for transmitting acquired torque from wind velocity to plurality of driven means (R1 ,R2)

150 thereby each driven means (R1 ,R2) with generator (G1 ,G2) getting stimulated to generate electricity.

In one aspect of the embodiment, the transmission means arrangement can be implemented in both vertical axis wind turbine and horizontal axis wind turbine.

155 In another aspect of the above embodiment discloses about a main driving means (D), which can be a disc or tapered edge means or flat shaped assembly or wheel or sheet or any suitable dimension which can move through rollers and transmit power or combination thereof. In another embodiment of the invention discloses about a wind turbine for generating electricity by

160 means of tapered engagement of power transmission means which includes tapered main driving means (D) and plurality of pair of oppositely rotating tapered driven means configured to enable relative speed and eliminate variable slip along the line of contact between tapered main driving means (D) and tapered driven means (R1 ,R2), the said wind turbine comprises of a tower assembly, a rotor assembly rotatably secured on the tower assembly with air foil blade arrangements. Accurately a power

165 transmission means configured to transmit the torque of rotor assembly to generator (G1.G2) for generating electricity, the said power transmission means includes at least one tapered main driving means (D) which is flexibly connected with rotor assembly and plurality of pair of tapered driven means (R1.R2) which is rotatably engaged with the tapered main driving means (D), The said flexible connection of tapered main driving means (D) configured to shift the centre of gravity of the turbine to a

170 lower point and structurally isolate the generators from the rotor for obtaining turbine dynamic/static stability and transmitting only the torque between the rotor and the motor. The said tapered main driving means (D) configured to move through plurality of said tapered driven means (R1.R2) for transmitting rotating torque to each driven means (R1.R2), each said tapered driven means configured to attach with shaft (S) of generator for generating electricity, each said tapered driven means (R) with

175 generator(G) assembly configured to provide predetermined favourable pressure on the tapered main driving means (D) to acquire optimum power, Wherein, when the wind turbine obtain cut in wind speed then the said tapered main driving means (D) moves through plurality of tapered driven means (R1 ,R2) for transmitting acquired torque from wind velocity to plurality of tapered driven means (Ri,R2) thereby each driven means (R1.R2) with generator (G1.G2) getting stimulated to generate electricity, wherein,

180 the said line contact region of the said tapered main driving means (D) comprises of plurality of contact points (X to Y) and each contact points engaged with corresponding matching contact points (P to Q) of the said tapered driven means (R1.R2) while power generation for maintaining relative speed between a tapered main driving means (D) and tapered driven means (R1.R2) thereby eliminating a variable slip along the line of contact, wherein, the said initial contact point (X) and final contact point (Y) of the said

185 tapered main driving means (D) are having a radius from the said centre rotating axis R, and R _n and corresponding contact points (P) and (Q) of the said tapered driven means (3) having a radius from centre rotating axis of generator n and r _n respectively, wherein the said contact points (X) and (Y) are having the linear velocity o)R, and oaR _n , and the said contact points (P) and (Q) are having the linear velocity ω ₉ n and ω ₉ r _n , wherein, the said radius ratio Ri and R2 of the said contact points (X) and (Y) of

190 the said tapered main driving means (1) are equal to radius n and r _n of matched contact points (P) and (Q) of the said tapered driven means (R1.R2) thereby achieving relative speed and eliminating the said variable slip along the line of contact. Yet another embodiment of the invention discloses about matching tapered roller driven assembly as 195 shown in figure 3 of the present invention. The matching of roller assembly along their line of contact are derived from the below formula,

Linear velocity of the main driving means at point 'X -F ,

Linear velocity of the main driving means at point Ύ -Rn ω,

Linear Velocity of the rolling means at point 'P - (Di/2) ω ₉ ,

200 Linear velocity of the rolling means at point 'Q - (D _n /2) ω ₉ ,

Equating the surface velocity of both main driving means and rolling based on engaging point X&P, we get

Ri ω =(Di/2) ω ₉

205 Equating the surface velocity of both main driving means and rolling based on engaging point Y&Q, we get

R _n ω =(D _n /2) ω ₉

ω ₉ / ω = 2Rn/D _n ©

Equate both ®&© we get,

Therefore, Ri/R _n =

From the above we can understand, how relative speed between roller driven transmission means (derived from reverse principle of cold rolling technique) are achieved by matching contact points of the tapered main driving means (1) and tapered driven means(3).

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Yet embodiment of the invention discloses about tapered region of both main driving means and driven means arrangement. Both the said main driving means (D) can have a tapered shape on a bottom region or top region or inner or outer or circumference region or combination thereof and the pair of tapered driven means (R1 , R2) engaged with corresponding contact region for maintaining the said 220 relative speed, eliminate variable slip along the line of contact and efficient/optimum power transmission.

Yet another embodiment of the invention discloses about position of tapered driving means on the flat main driving means (D), where generator assembly is correspondingly tilted/positioned along with 225 driving means (R) to accommodate with flat shape of the main driving means (D) which is clearly illustrated in Fig 4a&4b.

Yet another embodiment of the invention discloses about motoring mode of vertical axis wind turbine because this type of wind turbine does not have self-start. During motoring mode, the rotating rollers 230 (R1 &R2) (with generators) are act like a drive means/driving means for transferring starting torque to Main driving means (D) until reach. cut-in wind speed.

Yet another embodiment of the invention discloses about a said driven means (R1 , R2) can be a roller or tapered roller or any suitable shape which can acquire power from main driving means (D).

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Yet another embodiment of the invention discloses about a wind turbine, which can have a plurality of said main driving means (D) with plurality of pair of driven means (R1 , R2) for generating electricity in an effective manner. Further, both the said main driving means (D) and pair of driven means (R1 , R2) can have a tapered shape for efficient/optimum power transmission.

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Yet another embodiment of the invention discloses about applying contact pressure in the transmission means. The predetermined favourable contact pressure between the said main driving means (D) and the said pair of driven means (R1 , R2) can be enabled by means of an actuating means. The said predetermined favourable contact pressure is applied perpendicular to plane axis or suitable axis of 245 main driving means (D) by means of actuating means through both driven means (R1 , R2).

Yet another embodiment of the invention discloses about actuating means. The actuating means can be a linear/torsional spring or solenoid or pneumatic or hydraulic apparatus or electromagnetic means or self-actuating means or combination thereof.

250

Yet another embodiment of the invention discloses about a flexible connection between main driving means (D) and rotor assembly. The flexible connection is configured to bring down Centre of Gravity of the turbine to obtain turbine dynamic/static stability.

255 Yet another embodiment of the invention discloses about main driving means (D) and pair of driven means (R1 , R2) are floating with respect to the rotor and can be positioned anywhere coaxially with the turbine and connected flexibly with the rotor in order to tap the torque created by wind on the order and convert it into electricity using the generators. 260 Yet another embodiment of the invention discloses about the flexible connection between main driving means (D) and rotor assembly configured to shift the Centre of Gravity of the turbine to a lower point, thus obtaining better turbine dynamic/static stability. Further the flexible connection between main driving means (D) and rotor assembly is configured to structurally isolate the generators from the rotor, thus transmitting only the torque between the rotor and the motor, obtaining better overall

265 dynamic/static stability.

Further embodiment of the invention discloses about power transmission efficiency of roller driven mechanism.

The contact pressure between tapered rollers and tapered driving means can determine the power 270 transmission efficiency, which is achieved by maintaining optimum contact pressure between driven means (R1 &R2) and driving means (D).

- If the contact pressure between both driven means and driving means less than the optimum/required, the power transmission system cannot transfer required/optimum mechanical power because of slip.

275 - If the contact pressure between both driven means and driving means higher than the optimum/required, the mechanical power transmission system cannot transfer optimum/required mechanical power because of losses.

In our proposed arrangement required contact pressure is found experimentally by providing various weights and the resultant graph has derived which is illustrated in figure 5.

280 From the experiment, the optimum contact pressure has determined to achieve optimum power transmission.

ADVANTAGE OF THE INVENTION

1. The present transmission mechanism eliminates the need of chain and sprocket assembly thereby eliminating lubricant system and avoiding frequent maintenance.

2. Maintaining relative speed and eliminating variable/differential slip along the line of contact.

3. In case of erection point of view, if the existing turbine is erected with a large gear arrangement and large bearing assembly, it will consume more time.

4. Another advantage of the present invention is that it does not require a huge crane or more than one crane for erecting huge single generator. By comparison, each of the smaller generators on the wind turbine of the present invention can be lifted using a much smaller crane or winch that is locally available and can be mobilized for a small fee. The examples set forth above are provided to give those of ordinary skill in the art a complete 295 disclosure and description of how to make and use the embodiments of the roller driven vertical axis wind turbine, and are not intended to limit the scope of what the inventors regard as their disclosure. Modifications of the above-described modes for carrying out the disclosure may be used by persons of skill in the art, and are intended to be within the scope of the following claims.

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