Title: Gravity actuated windmill sails
The following specification particularly describes the invention and the manner in which it is to performed
Field of invention
This invention relates to the wind energy, more particularly to the field of making wind energy cost effective and easy to install.
This invention is useful in small and large wind mills. This invention is useful in making electricity from wind. This invention can also be used to draw water from wells for irrigation and other purposes.
Prior art and problem to be solved:
Most of the previous wind mills have blades or vanes making an angle with direction of wind and plane of rotation. These are costly to manufacture and install. These can work only in high velocity wind. These can utilize only small fraction of wind energy.
Objective of the invention:
The objective of this invention is to produce wind energy. Another object of this invention is to make a windmill which can run in
low as well as high velocity wind efficiently. Yet another object of this invention is to make low cost windmill so that produced electricity may be economically viable. Further object of this invention is to make a windmill that can save itself from breaking in high storm wind.
Summary of invention
Accordingly the invention provides an apparatus consisting of a horizontal shaft installed on a vertical axle. This axis helps the shaft to rotate in a horizontal plane if there is a change in direction of wind. The shaft is fitted with three or more arms. These arms are distributed symmetrically around the shaft. Each arm consists of a frame of rectangular or square or any other shape. Each frame is fitted with a sail of strong cloth or sheet of flexible material. This sail is fixed to outer side or to the inner side of the frame, the sail is not fixed to other end. Other end is attached to a rod or plate to keep it strait. This rod or plate is free to move towards or away from shaft under the effect of gravity. If sail is fixed to the outer side of a frame, the sails of other frames belonging to other arms are also fixed to outer side. If the sail of one frame is fixed to inner side, sails of all other frames will be fixed to inner side. Each arm fixed to the shaft has a supporting web, made of wires or rods. This web supports the sail, prevents the bulge in the sail when wind pushes it. This web saves the sail from tearing. All the arms are

similar in every respect. The sail of each arm is attached to sides of corresponding frame transverse to shaft, by rings these rings can slide near and away from the shaft. This sliding movement of rings makes the sail to spread and obstruct the path of wind through the frame of an arm. In a preferred embodiment of invention sail is fixed to the outer side of the frame. In this case when an arm is in the upper half of rotational path, the rings attached to its sail slide towards shaft and space surrounded in frame is obstructed to wind. The wind pushes this arm to rotate shaft. When this arm comes in lower half of its circular path, its rings slide away from shaft due to gravitation to fold the sail near the outer side of the frame, leaving whole space surrounded in the frame, open for wind to pass freely. As soon as any of the arms come just above the shaft rings holding its sails slide towards shaft to open and spread its sail, obstructing space of frame for the wind. The sail receives energy of wind, transmit it to shaft which rotate to rotate electricity generater. Same is the story of rotation of all other arms. In case there is a storm, rotational velocity increases and rings will experience outward centrifugal force. This decreases area obstructed by the sail, this in turns decrease the speed. A balance between speed and space obstructed is formed. Windmill rotor rotates with steady speed even in storm.
The above mentioned preferred embodiment acts like a speed governer in high speed winds. But if the sail is fixed to the opposite side, that is, the side near and parallel to the shaft, it spreads when its arm comes below the shaft. In this case there is no control on speed in high wind since centrifugal force pulls the rings away from shaft only to spread open the sail and to enhance speed further.
Detailed description of invention:
This invention is a windmill to receive kinetic energy of wind, transmit to electric generator. The rotor consists of a horizontal shaft, three or more arm attached to it, ball bearings and gear to transmit the energy. Each arm fixed to the shaft has Components. These components are 1 rectangular or square frame of metal or wooden or any other rigid material rods. 2 a web structure of metal or wooden or any other rigid material having area comparable to the frame. 3 A sail of cloth or flexible sheet of strong material having area comparable to that of the frame. 4 A plurality of rings encircling those two sides of the frame which are transverse to the length of shaft. Arms 3 or more in number, are fixed symmetrically around the shaft. These arms hold the sails in spread position in front of the wind when moving away from wind. On its return journey towards the wind the sail cloth folds itself to one end of the frame. This time most of the area enclosed by the frame remains unobstructed and open for the wind to pass through it. The sail is fixed in such a way that its one side is fixed to the outer side of the frame. This side is parallel to length of the shaft. Also this side is far away from the shaft. The other end of the sail is not fixed to any side of the frame. It is fixed to a rod or bar of metal or wood or any other material. This rod or bar keeps this end of the sail straight. In some other embodiments of the invention, this bar work as base to

roll the sail on it. This rod or bar remains free to move away from the shaft and towards the shaft to open or fold the sail.
The frame and the web are fixed to each other at vertices only. Web is kept behind the frame looking from the side of the wind. This means that during its journey around the shaft web remains ahead of the frame attached to it. This web supports the sail, prevents bulge in the sail and save it from tearing in strong winds.
The rings encircle the sides of the frame transverse to the length of shaft. These rings are free to move along the length of their sides. The rings are attached to the sail in such away that the distance between any two consecutive rings is same. When an arm is in the upper half of the circular path of its journey around the shaft, the rings and bar attached to the sail are pulled down by gravity. This downward pull opens the sail to fill the entire space of the frame. The wind pushes the sail which is supported by web behind it. When this arm of windmill enter the lower half of the circle,there is tilt in the position. Rings and bar attached to sail experience gravitational pull to fold and push the sail near the outer side to which the sail is fixed. This creates the open space in the frame so that wind passes freely without giving drag to the arm. The windmill rotor of this invention utilize maximum part of winds kinetic energy. In yet another embodiment of this invention having multiple part sails attached to each arm, area receiving wind energy can be increased. This type is useful where wind velocities are small. In such rotors each part of the sail of an arm has its own part of frame area to obstruct during upper half journey and open during lower half journey.

Statement of claims:

I claim,
1. a windmill rotor shaft having a plurality of arms, each arm comprising; a front frame, a web paralal to the said frame; a sail fixed to one side of said frame parallel to length of shaft and attached to the plurality of rings slidable along those sides of the front frame which are transverse to length of the shaft
2. windmill rotor shaft as defined in claim 1, wherein the web parallel to the front frame is fixed to the said frame on outer or inner sides parallel to shaft
3. windmill rotor shaft as defined in claim 1 wherein each arm having a sail spreadable and foldable by sliding movement of the rings attached to it.
4. windmill rotor shaft as defined in claim 1, wherein each arm having a web made of metal wires.
5. windmill rotor shaft as defined in claim 1 wherein each arm having aweb
made of metal rods or rods of woods or of any other rigid material
6. a windmill rotor shaft of claim 1 wherein the sail is attached to a rod or bar of any rigid material,on theside opposite to that fixed to the frame.
7. windmill rotor shaft as defined in claim 1 wherein the sail holding rings are movable along the transverse sides of frame due to gravity when the arm to which these are attached, moves above and below the shaft alternately during its journey around the shaft.
8. windmill rotor shaft having plurality of complex arms, each complex arm comprising a plurality of front frames joined to each other in a series,each frame linked to a supporting web;a sail fixed to one side of each frame, parallel to length of shaft and attached to plurality of rings slidable along those sides of the frame which are transverse to length of shaft.
9. Windmill rotor shaft wherein the sail is roll able on and unroll able off a bar or rod falling under the effect of gravity during the journey of the arm around the shaft.
10. an apparatus substantially as herein above described in the specification.