FIELD OF THE INVENTION
This invention relates to a down wind type micro-wind turbine generator. The invention relates in particular to a down-wind type micro-wind turbine generator in which the turbine rotor is directly coupled to a rim of a micro-wind generator.
Prior Art.
Micro-wind turbines of the art use a two pole permanent magnet generator rotated at a high speed by using a step up gear box or friction/belt drive to increase the rpm of the generator. Such an indirect drive mechanism results in losses of the input mechanical power of the generator. Further, the rotor blades of the prior art devices once damaged due to cyclone or other calamites, those are generally difficult to repair/replace. Further, due to use of belt drive/gear-box, the maintenance of the device is rather costly and time consuming. The micro-wind turbines presently in use do not normally have any support structures to protect the device being damaged against cyclone. Additionally, the basic components of the existing turbines for example, rotor blades, magnets, stator coils are tailor made and thus expensive. Since the peripheral speed of magnetic poles of prior art devices is comparatively lower due to use of a two-pole permanent magnet generator, the devices of prior art do not have much of a flexibility in selection of the locations where those can be installed.
OBJECTS OF THE INVENTION
It is an object of this invention to propose a down-wind type micro-wind turbine generator; which eliminates the drive losses associated with step-up gear box or belt drive.
It is a further object of this invention to propose a down-wind type micro-wind turbine generator, utilizing parts of an ordinary bicycle and parts of a scooter dynamo/magneto, and which is cost effective.
Another object of this invention is to propose a down-wind type micro-wind turbine generator, particularly for use in free standing type micro-wind farms for roof top locations.
Yet another object of this invention is to propose a down-wind type turbine generator, particularly for use in micro-wind farms for generating and supplying power to installations not connected to the grid, such as petrol pumps and restaurants on high ways.
At the outset of the description which follows, it is to be understood that the ensuing description only illustrated a particular form of this invention. However, such a particular form is only an exemplary embodiment and the teachings of the invention is not intended to be taken restrictively.
SUMMARY OF THE INVENTION.
According to the present frwention there a down wind type micro-wind turbine generator for generation and supply of electrical power to micro-wild farms through storing in a 12V battery comprising
a wind turbine rotor comprising of a pluratity of compound blades consisthg of plastic sheets tied to a square wire mesh mounted on a bicycle wheel which is comprised of a rim and a hub with spokes and an axle with metal balls disposed therein for bearing, the wire mesh frame being Bed to a pipe which in turn being tied to the bicycle wheel and the outer ends of each compound blade being tied to the adjoining blades; a generator consisting of a rotor having 12 to 36 poles mounted at the inner periphery of a bicycle rim tied to the wheel, the magnetic poles being fixed to the rim via screws through the holes meant for the spokes; a stator consisting of coils being fixed on a bicycle rim; the support frame/rim being fixed to a support structure consisting of a beam suspended from the bicycle fork which is inserted into a hinged pipe being provided with a counter weight at its bottom, the said support frame providing means for correction of orientation of rotor plane perpendicular to wind during change of wind direction and means of restoring couples for tilting, the rotor up positions the blades at an angle to the wind.
At the outset of the description which follows, it is to be understood that the ensuing description only illustrates a particular form of the invention. However, such a particular form is only exemplary embodiment and the teachings of the invention is not intended to be taken restrictively.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS.
Fig.l- shows an overall view of the Micro wind turbine generator according to the invention.
Fig.2- shows a turbine rotor with compound blades of the micro turbine generator.
Fig. 3 - shows an exploded view of a single compound blade of the turbine rotor.
Fig.4- shows the tying arrangement of a plastic type blade of a turbine rotor.
FIG. 5- shows a cross-sectional view of a micro-wind turbine generator.
Fig.6. - shows an end view of the rim-mounted generator.
Fig.7- shows a system of direction orientation of the turbine rotor
Fig. 8- shows the wind generator in a tilted down position.
Fig.9- shows the features of protection of the turbine generator against strong winds.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION.
One embodiment of the wind turbine rotor (1) consisting of a plurality of compound blades (2) mounted on a first bicycle wheel (3) is shown in Fig. 2. The bicycle wheel (3) consists of a rim (4) and a hub with spokes (5) and an axle (24) with balls for the bearing. Each compound blade (2) consists of plastic sheets (17) preferably 1mm thick and about 80mm wide tied to a 3" to 3"square wire mesh (18) as shown in fig. 3.
In an alternative embodiment the rotor blades (2) can be made from plastic bucket cut length wise. The plastic sheets are tied to the wire mesh frame(18) in such a way so as to give the required blade angles at the tip and the blade root. The wire mesh frame (18) with the 5PVC sheets is tied to a stick/ aluminum pipe, which in turn is tied to the bicycle wheel. The outer ends of the each compound blade (2) is tied to the adjoining blades.
On a commercial scale the compound blades (2) can be moulded in plastic, integral with tube meant for fixing the blade with bicycle wheel. Also necessary steel reinforcement wires can be moulded integral to make them stronger.
This type of rotor (1) with compound blades (2) has the advantage of being suitable for low wind speeds, which in-turn means lesser installation height, and hence making it
suitable for roof-top application and for mounting on the poles of street lights of remote areas.
For medium winds speeds, the turbine rotor design uses pieces (19) cut form a long plastic drum and tied to the spokes of the bicycle wheel (3) as shown in fig. 4. The curved portion of the drum (19) is complementary configured to an aerodynamic profile. The trailing portion of the blade (2) is tied to the adjoining spoke (-4-) (5) using a spring (20) or a rubber strip so as to give it the required angle during normal operation and to open out in strong winds and prevent over speeding of the rotor.
For higher wind speeds, the turbine rotor is configured with moulded plastic blades which have the cross section to give the required profile and strength. Also the blade roots are moulded in such a way that they can be easily fixed to the bicycle wheel rim and spokes. A commercial model will have interchangeable blades so that damaged blades can be easily replaced and the rotor can be easily and quickly put back into service.
The generator (11) consists of a rotor (6) having 20 to 36 poles (8) mounted on the inner periphery of a bicycle rim (6) which Is fixed to the wheel (3) of the turbine rotor (1) on its side as shown in fig. 5 and 6. The magnetic field is created using the permanent magnet poles (8) of a scooter dynamo/magneto. These magnet poles (8) are fixed to the rim (6) using screws (10) through the holes meant for the spokes.
The stator (?) consists of coils (9) used in a scooter dynamo. These coils (9) are fixed inside a bicycle rim (7) of a smaller diameter. This stator frame/rim (7) in turn fixed to a support structure.
Thus the permanent magnet poles, about 20 to 36 in number and fixed to the rim rotate around the stator coils, thus generating electricity. The current generated in the stator coils (9) is carrfed by a two cored insulated copper wire led through the central hote in the bicycle fork (13). The current generated is stored in 12Vbattery.
It is estimated that about 40 to 50W can be generated by this wind generator. Use of high energy magnets would increase the generation capacity substantially.
This is a down-wind type of wind turbine i.e. wind turbine rotor (1) is on downstream side of the vertical axis (21) of orientation. The plane of wind turbine rotor (1) is offset from the vertical axis (21) of orientation as shown in Fig.7. When the wind direction has changed and is not perpendicular to the plane of the rotor, but an angle; then the force of wind on the rotor produces a couple which brings about the necessary correction in orientation and makes rotor plane perpendicular to wind.
The support structure consists of beam (23) supporting the rotor is suspended form the bicycle fork (13). The bicycle fork (13) is hserted Into a pipe (14). The supporting pipe (14) is provided with a hinged connection (26) with a counter weight (16) fixed at the bottom end of the pipe (14). A hinged prop (IS) is attached to pipe (14) at a suitable height. This arrangement thus permits tilting of the support pipe (14) to a convenient
height for initial erection as well as subsequent maintenance. This arrangement as shown in Fig.8 is similar to the road barrier at check posts for collection of octroi tax or toll tax for bridges. The hinged prop (15) is so located that when the support pipe (14) with wind turbine mounted on it, is lowered /tilted for maintenance it automatically rests on the prop (15) with the rotor (1) at convenient height. This tilting pole arrangement is so convenient that only one man can easily erect the wind turbine, lower it for maintenance. On account of the counter-balance weight (16) on the bottom end of the support pole and the arrangement of guy ropes (22) it is possible to lower the wind turbine within a few minutes and protect the wind turbine against storms/cyclones.
When the wind turbine is to be used for rooftop micro-wind farms they are to be used in clusters of 4 viz. at the corners of a square, forming a self supporting structure.
This wind turbine is provided by a safety feature to protect it against strong winds.
The beam (23) supporting the rotor is suspended from the end of bicycle fork (13) as shown in the fig.9. The resultant force on the rotor (1) produces a couple trying to rotate up the beam (23) supporting rotor, about it's point of suspension form the bicycle fork (13). Tilting the rotor up positions the blades (2) at an angle to the wind thus prevent the rotor from over speeding. The restoring couple is provided by a restoring weight (25) suspended by a hinged connection from the fork (13) and the beam (23) supporting rotor (1) . A more sophisticated design can have the hydraulic door closing mechanism for smooth retraction.
The current generated by the wind generator would be stored in a 12V battery and used directly or through an inverter. The wind generators can be used in a cluster to increase the generation capacity thus forming a micro-wind farm.
This design of wind generator can be used for a number of applications some of which are listed below:
i) For lights, radios, T.V.s in rural houses.
ii) For street lighting in rural areas. The pipe supporting the wind turbine would
serve the dual purpose of lamp post, iii) For the restaurant and petrol pumps on highways.

WE CLAIM
1. A down wind type micro-wind turbine generator for generation and supply of
electrical power to micro-wind farms through storing in a 12V battery comprising
a wind turbine rotor (1) comprlsfcTg of a plurality of compound blades (2) consisting of plastic sheets (17) tied to a square wire mesh (18) mounted on a bicycle wheel (3) which is comprised of a rim (4) and a hub with spokes (5) and an axle (24) with metal balls disposed therein for bearing, the wire mesh frame (18) being tied to a pipe which in turn being tied to the bicycle wheel (3) and the outer ends of each compound blade being tied to the adjointig blades; a generator (11) consisting of a rotor (6) having 12 to 36 poles (8) mounted at the inner periphery of a bicycle rim (6) tied to the wheel (3), the magnetic poles being fixed to the rim (6) via screws (10) through the holes meant for the spokes (5); a stator (7) consisting of coils (9) being fixed on a bicycle rim (7); the support frame/rim (7) being fixed to a support structure consisting of a beam (23) suspended from the bicycle fork (13) which is rserted into a hinged pipe (14) being provided with a counter weight (16) at its bottom, the said support frame providing means for correction of orientation of rotor plane perpendicular to wind during change of wind direction and means of restoring couples for tilting, the rotor up positions the blades (2) at an angle to the wind.
2. The generator as claimed in claim 1 wherein the said means for correction of orientation of rotor plane is provided by maintaining the wind turbine rotor (1) is on downstream side of the vertical axis (21) of orientation, the plain of the turbine rotor (1) being adopted offset from the vertical axis (21) of orientation so that when the wind direction changes at an angle to the plane of the rotor, the force of wind on the rotor produces a couple to bring about necessary correction in orientation in making the rotor plane perpendicular to wind.
3. The generator as claimed in claim 1 wherein the said means of restoring couple comprises a restoring weight (25) suspended by a hinged connection from the fork (13) and the beam (23), tilting the rotor up positions the blades (2) at an angle to wind.
4. The generator as claimed in claim 1, wherein said turbine comprises a plurality of said blades (2) having one end tied to the bicycle wheel (3) and the outer ends being tied to the adjoining blades.

5. The generator as claimed In claim 1, wherein each blade Is configured to have a curved portion (19) to complement an aerodynamic profile, and wherein the trailing portion of the blades being tied-up with adjoining spoke (5) so as to open out under strong wild for preventing over-speeding of the rotor.
6. The generator as claimed in claim 1, wherein an insulated copper wire is provided to transmit the current generated by said stator coils of the mounted generator.
7. A down-wind type micro-wind turbine generator as substantially herein described and illustrated with reference to the accompanying drawings.