FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF INVENTION
Windmill generator
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR
Hangal Anand, Crompton Greaves Limited, Advance Motor Design and Technology Centre (AMDTC), CG Global R&D Centre, Kanjurmarg (East), Mumbai 400042, Maharashtra, India, an Indian National
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention and the manner in which it is to be performed:

FIELD OF INVENTION
This invention relates to a windmill generator.
PRIOR ART DESCRIPTION
Windmill generators are environment friendly and non-polluting machines employing naturally, abundantly and freely available wind energy for generation of electricity. A windmill generator comprises a shaft horizontally rotatably mounted in a pair of end shields using two bearings, one bearing in each of the end shields. An armature is rigidly mounted on the shaft. A stator is disposed over the armature describing an air gap against the armature and located in a stator body held onto the end shields. One end of the shaft protrudes outside the corresponding end shield and is fitted with a fan. In another construction of the windmill generator, the stator is disposed over the shaft describing a clearance against the shaft and facing the armature mounted on the shaft and is held onto the adjacent end shield. The generator is usually mounted on a tower. In order to carry out repairs and maintenance work after installation of the generator on the tower, it is necessary to bring down the whole generator to the ground level. This is cumbersome, difficult, time consuming and reduces power generation. Use of two bearings increases the initial and recurring cost and also the maintenance cost of the windmill generator. Wind energy being captured by the fan is transmitted to the armature via the shaft. As a result, there are transmission losses and reduction in power generation. The shaft is very long extending along the length of the windmill generator and protruding out of one of the end shields. Energy losses also occur due to the energy expended for driving the long shaft. Further material cost of the fan shaft is increased.
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OBJECTS OF INVENTION
An object of the invention is to provide a windmill generator which minimises transmission losses and improves power generation.
Another object of the invention is to provide a windmill generator which is simple in construction and easy and convenient to repair and maintain within reduced time.
Another object of the invention is to provide a windmill generator which is economical.
Another object of the invention is to provide a windmill generator which requires minimum maintenance.
Another object of the invention is to provide a self setting windmill generator which minimises transmission losses and improves power generation.
Another object of the invention is to provide a self setting windmill generator which is simple in construction and easy and convenient to repair and maintain within reduced time.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention there is provided a windmill generator comprising a support
frame having a base and a pair of slotted upstanding extensions, the base being mounted
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on a platform at the upper end of a tower, a shaft horizontally disposed and rigidly fitted in the slotted upstanding extensions, a fan rotatably mounted on the shaft using a bearing, an armature comprising a plurality of permanent magnets located within the fan radially distributed around the shaft and exposed at the inner side of the fan and a stator disposed over the shaft describing a clearance against the shaft and fan and held onto the adjacent slotted upstanding extension, the stator comprising a magnetic material core having electric conductors wound thereon and facing the permanent magnets of the armature and a protective cover fixed to the fan and extending over the outer surface of the stator.
According to the invention there is also provided a self setting windmill generator comprising a support frame having a base and a pair of slotted upstanding extensions, the base being located on a platform at the upper surface of a tower and fitted to a spindle vertically rotatably held in the platform using a bearing, a rod disposed horizontally with its one end fitted in the spindle and the other end fitted with a vane, a shaft horizontally disposed and rigidly fitted in the slotted upstanding extensions, a fan rotatably mounted on the shaft using another bearing, an armature comprising a plurality of permanent magnets located within the fan radially distributed around the shaft and exposed at the inner side of the fan and a stator disposed over the shaft describing a clearance against the shaft and fan and held onto the adjacent slotted upstanding extension, the stator comprising a magnetic material core having electric conductors wound thereon and facing the permanent magnets of the armature and a protective cover fitted to the fan and extending over the outer surface of the stator.
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The following is a detailed description of the invention with reference to the accompanying drawings, in which
Fig 1 is a crosssectional view of a self setting windmill generator according to an embodiment of the invention;
Fig 2 is an isometric view of the support frame and fan of the windmill generator of Fig
l;
Figs 3 and 4 are inner side view and crosssectional view of the fan of the windmill generator of Fig 1, respectively;
Figs 5 and 6 are inner side view and crosssectional view of the stator of the windmill generator of Fig 1, respectively;
Fig 7 is crosssectional view of a windmill generator according to another embodiment of the invention.
The windmill generator 1 as illustrated in Figs 1 to 6 of the accompanying drawings comprises a U-shaped frame 2 having a base 3 and a pair of slotted upstanding extensions 4. The slots in the upstanding extensions are marked 4a (Fig 2). The base is located on a platform 5 at the upper surface of a tower 6 and fitted to a spindle 7 vertically rotatably held in the platform using a bearing 8. 9 is a rod disposed horizontally with its one end
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fitted in the spindle and the other end fitted with a vane 10. 11 is a shaft horizontally disposed and rigidly fitted in the upstanding extensions. 12 is a fan comprising an annular body 13 rotatably mounted on the shaft using another bearing 14. The shaft hole in the fan is marked 11a (Figs 3 and 4). The fan body describes an annular recess 15 at the inner side thereof and has a plurality of blades 16 provided on the outer circumference thereof radially spaced apart. An armature comprising a plurality of permanent magnets 17 are located in the annular recess in the annular body radially distributed around the shaft and exposed at the inner side of the fan. 18 is a stator comprising a circular shaped body 19 formed with an annular groove 20 at the inner side thereof. The stator is disposed over the shaft through shaft hole lib (Figs 5 and 6) therein describing a clearance against the shaft. The stator is held onto the respective slotted upstanding extension 4 by bracket 21. 22 is a magnetic material core located in the annular groove and having electric conductors 23 (Fig 5) wound thereon facing the permanent magnets of the armature. 24 is a protective cover fixed to the fan and extending over the outer surface of the stator. Due to wind forces acting on the fan blades, the fan rotates around the shaft alongwith the permanent magnets of the armature. Because of the slots in the upstanding extensions, the upstanding extensions do not offer practically any resistance to the flow of air to the fan and air flows to the fan also through the upstanding extensions freely and smoothly. As the permanent magnets of the armature rotate around the shaft, an axial magnetic field is generated around the magnetic material core of the stator and an electric current is induced in the electric coils wound around the magnetic material core. The current is conducted away from the coils in the usual manner. Due to the wind forces, the vane also rotates and causes the spindle to
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rotate in the platform in the direction of the wind alongwith the U-shaped frame and the windmill generator. This helps the windmill generator to align or selfset in the wind direction so as to capture the maximum wind energy blowing in the direction of the windmill generator and correspondingly increase electric power generation. The windmill generator as illustrated in Fig 7 of the accompanying drawings is fixed on the platform. In both the embodiments of the windmill generator of the invention as illustrated and described above, the shaft and stator are stationary and the armature is rotated directly by the fan. Therefore, wind energy being captured by the fan is directly transmitted to the armature and transmission losses are reduced and power generation is improved. The shaft is comparatively very short thereby reducing the material cost thereof. Due to the shaft being stationary, there is no energy required for driving it thereby power generation is further improved. The U-shaped frame provides sufficient work area for mechanics to stand and to carry out repair and maintenance work on the windmill generator. Therefore, there is no need for bringing down the whole generator to the ground level for repairs and maintenance work. Maintenance and repairs to the windmill generator can be carried out easily and conveniently and within reduced time. Power generation is also improved because of the reduced time for repairs and maintenance. The windmill generator of both the embodiments is simple in construction. The windmill generator of Fig 1 has the added advantage of being self setting. In the case of the embodiment of the windmill generator of Fig 7 only one bearing is used correspondingly reducing the cost of the windmill generator including its maintenance cost. The invention also eliminates the endshields and the cost thereof.
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The fan and armature and stator configuration /construction and configuration / construction of the U-shaped support frame can vary. The frame is essentially to support the windmill generator and to provide work area for mechanics. Any support frame giving such functional benefits can be used in the windmill generator of the invention. The support frame need not be U-shaped. Such variations of the windmill generator of the invention are to be construed and understood to be within the scope of the invention.
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We claim:
1. A windmill generator comprising a support frame having a base and a pair of slotted upstanding extensions, the base being mounted on a platform at the upper end of a tower, a shaft horizontally disposed and rigidly fitted in the slotted upstanding extensions, a fan rotatably mounted on the shaft using a bearing, an armature comprising a plurality of permanent magnets located within the fan radially distributed around the shaft and exposed at the inner side of the fan and a stator disposed over the shaft describing a clearance against the shaft and fan and held onto the adjacent slotted upstanding extension, the stator comprising a magnetic material core having electric conductors wound thereon and facing the permanent magnets of the armature and a protective cover fixed to the fan and extending over the outer surface of the stator.
2. The windmill generator as claimed in claim 1, wherein the fan comprises an annular body rotatably mounted on the shaft using the said bearing and describing an annular recess at the inner side thereof, the fan having a plurality of blades provided on the outer circumference of the annular body radially spaced apart, the permanent magnets of the armature being located in the annular recess in the annular body and the stator comprises a circular shaped body formed with an annular groove at the inner side thereof, the magnetic material core having the electric conductors wound thereon being located in the annular groove and facing the permanent magnets of the armature.
3. The windmill generator as claimed in claim 1 or 2, wherein the support frame is a U-shaped frame having a base and a pair of slotted upstanding extensions.
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4. A self setting windmill generator comprising a support frame having a base and a pair of slotted upstanding extensions, the base being located on a platform at the upper surface of a tower and fitted to a spindle vertically rotatably held in the platform using a bearing, a rod disposed horizontally with its one end fitted in the spindle and the other end fitted with a vane, a shaft horizontally disposed and rigidly fitted in the slotted upstanding extensions, a fan rotatably mounted on the shaft using another bearing, an armature comprising a plurality of permanent magnets located within the fan radially distributed around the shaft and exposed at the inner side of the fan and a stator disposed over the shaft describing a clearance against the shaft and fan and held onto the adjacent slotted upstanding extension, the stator comprising a magnetic material core having electric conductors wound thereon and facing the permanent magnets of the armature and a protective cover fitted to the fan and extending over the outer surface of the stator.
5. The windmill generator as claimed in claim 4, wherein the fan comprises an annular body rotatably mounted on the shaft using the said another bearing and describing an annular recess at the inner side thereof, the fan having a plurality of blades provided on the outer circumference of the annular body radially spaced apart, the permanent magnets of the armature being located in the annular recess in the annular body and the stator comprises a circular shaped body formed with an annular groove at the inner side thereof, the magnetic material core having the electric conductors wound thereon being located in the annular groove and facing the permanent magnets of the armature.
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6. The windmill generator as claimed in claim 4 or 5, wherein the support frame is a U-shaped frame having a base and a pair of slotted upstanding extensions.
Dated this 29th day of June 2007.

(Jose M A) of Khaitan & Co
Crompton Greaves Limited By their Agent & Attorney
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ABSTRACT
A windmill generator (1) comprising a support frame (2) having a base (3) and a pair of slotted upstanding extensions (4). The base is mounted on a platform (5) at the upper end of a tower (6). A shaft (11) is horizontally disposed and rigidly fitted in the slotted upstanding extensions. A fan (12) is rotatably mounted on the shaft using a bearing (14). An armature comprising a plurality of permanent magnets (17) is located within the fan radially distributed around the shaft and exposed at the inner side of the fan. A stator (18) is disposed over the shaft describing a clearance against the shaft and fan and held onto the adjacent slotted upstanding extension. The stator comprises a magnetic material core (22) having electric conductors (23) wound thereon and facing the permanent magnets of the armature. A protective cover (24) is fixed to the fan and is extending over the outer surface of the stator (Fig 1).