FORM 2
THE PATENTS ACT, 1970
(39 of 1970) As amended by the Patents (Amendment) Act, 2005
AND
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2005
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
An improved fan assembly and self cooled or forced cooled motor with said improved fan assembly
APPLICANTS :
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company.
INVENTOR (S):
Barve Bharat Anant, Mettem Navadeep and Piyada Mumtazul Hassan; all of
Crompton Greaves Limited, FHP (M4) Commercial Motors Division, 196-198,
Kundaim Industrial Estate, Kundaim, Ponda, Goa-403115, India; all Indian
Nationals.
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 THE INVENTION:
This invention relates to the field of cooling systems for motors.
Particularly, this invention relates to fans for self cooled motors or forced cooled motors.
Specifically, this invention relates to an improved fan assembly and self cooled or forced cooled motors with said improved fan assembly by changing speed of fan.
BACKGROUND OF THE INVENTION:
Motors are heat generating mechanical assemblies. The heat output is due to various motor losses. For working of motors, it is imperative that this byproduct of heat does not increase beyond defined thresholds. Hence, a ventilating or cooling system for such motors is necessary.
Fan cooled motors or self cooled motors feature an axial fan (or axial in radial out) attached to the shaft of the motor (usually but not necessarily on the opposite end as the output shaft) that spins with the motor, providing increased airflow to the motor's internal and external parts which aids in cooling. This fan draws air over the motor with or without fins, removing excess heat and thereby cooling the motor.
The placement of the fan is at a drive or non-drive end of the motor. According to the prior art, the cooling fan was directly mounted on motor shaft. So, fan rotates at the same speed as that of the motor.

The cooling curve between fan speed and air flow followed by the fan of the motor is a U-curve. Therefore, for every motor - fan combination, an optimum speed of cooling is not necessarily obtained at the rotation-per-minute offered by the motor shaft upon which the fan is installed. Also, merely increasing fan speed also may not necessarily optimally or efficiently cool the motor. Hence, there has to be synchronism between fan speed and motor speed operation in terms of its cooling curve.
OBJECTS OF THE INVENTION:
An object of the invention is to provide efficient cooling of a motor and its associated assemblies.
Another object of the invention is to provide appropriate cooling of a motor.
Yet another object of the invention is to increase cooling of motor.
Yet another object of the invention is to reduce motor cost by reducing active material content.
Still another object of the invention is to increase functional life of motor.
SUMMARY OF THE INVENTION:
According to this invention, there is provided an improved fan assembly adapted for a motor, said fan assembly comprises:
a belt and pulley arrangement between a motor shaft at drive or non-drive end of said motor and a fan mounted on said shaft through a rolling bearing, said

belt and pulley being driven by said motor shaft and driving said fan, said belt and pulley being of pre-defined dimensions and configuration in accordance with desired fan speed in correlation with rotation of motor shaft.
According to this invention, there is also provided a self cooled or forced cooled motor with said improved fan assembly adapted for a motor, said fan assembly comprises:
a belt and pulley arrangement between a motor shaft at drive or non-drive end of said motor and a fan mounted on said shaft through a rolling bearing, said belt and pulley being driven by said motor shaft and driving said fan, said belt and pulley being of pre-defined dimensions and configuration in accordance with desired fan speed in correlation with rotation of motor shaft.
Typically, said assembly includes a first pulley mounted on a first rolling bearing on said end cover, said first pulley and said first bearing adapted to be radially spaced apart with respect to said shaft.
Typically, said assembly includes a second pulley integrated in said fan mounted on a second rolling bearing, said second rolling bearing mounted on said shaft at predefined location.
Typically, said assembly includes a first belt adapted to be looped around said shaft at one end and a first pulley at another end.
Typically, said assembly includes a second belt adapted to be looped around a radially spaced apart motor-mounted first pulley and a second pulley.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
The invention will now be described in relation to the accompanying drawings, in which:
Figure 1 illustrates an isometric view of the improved fan assembly; and
Figure 2 illustrates another isometric view of the improved fan assembly.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
According to this invention, there is provided an improved fan assembly and self cooled or forced cooled motor with said improved fan assembly.
Figure 1 illustrates an isometric view of the improved fan assembly.
Figure 2 illustrates another isometric view of the improved fan assembly.
In accordance with an embodiment of this invention, there is provided a plurality of belts' (12, 13) and a plurality of pulleys' (14, 15) arrangement between the motor shaft (16) at the drive or non-drive motor end and the fan (18). The said cooling fan (18) is mounted on shaft (16) with the help of rolling bearing and is driven by the belts' (12, 13) and pulleys' (14, 15) arrangement. The inner race of said second rolling bearing rotates at same speed that of motor shaft and outer race rotates at the same speed (predefined resulting from the said belts' and pulleys' arrangement) of the said fan.
Each of these pulleys is bearing mounted.

A second pulley (14) is mounted on a second bearing which is installed at the non-drive end disc (24) of the motor. The first pulley (14) is mounted on a first bearing.
Said first pulley (14) has two grooves with pre-defined dimensions each for the said belts (12, 13). Said second pulley (integral part of cooling fan (18)) has one groove with predefined dimensions for the said second belt (13)
A groove on the shaft (16) of the motor enables fitting of a first belt (12) which is looped about first groove of first pulley (15) and the groove on the shaft. The first belt (12) is driven by the shaft (16) which in turn drives the first pulley (15). This first pulley (15) mounted on a first bearing is in a radially spaced apart manner with respect to the shaft (16) which is co-axial to the end disc (24) of the motor and fan (18).
The second rolling bearing is fitted on to the motor shaft. The second pulley (14) is mounted on to the second bearing. The second pulley is an integral part of the fan. The second belt (13) is looped over the second groove of the first pulley (15) and groove of the second pulley.
As the motor shaft (16) rotates according to the drive of the motor, the first belt (12) is engaged which drives the radially spaced apart first pulley (15). This first pulley (15), in turn, engages the second belt (13) and drives the fan mounted second pulley (14) to rotate the fan.
Thus, due to this arrangement, step up of fan speed can occur. Any ratio of fan speed to motor speed can be achieved by altering pulley dimensions. Cooling of fan is governed by a U-curve. Hence, an optimum speed of fan rotation can be

designed to be achieved by this arrangement, instead of merely increasing the fan rotation speed. This also results in increased life of motor.
According to a non-limiting exemplary embodiment, a 4-pole motor, on full load, rotates at 1400 RPM. With this invention, the fan of the motor can be rotated at higher speed like 5600 RPM (4 times).
While this detailed description has disclosed certain specific embodiments of the present invention for illustrative purposes, various modifications will be apparent to those skilled in the art which do not constitute departures from the spirit and scope of the invention as defined in the following claims, and it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

We claim,
1. An improved fan assembly adapted for a motor, said fan assembly
comprising:
- a belt and pulley arrangement between a motor shaft at drive or non-drive end of said motor and a fan mounted on said shaft through a rolling bearing, said belt and pulley being driven by said motor shaft and driving said fan, said belt and pulley being of pre-defined dimensions and configuration in accordance with desired fan speed in correlation with rotation of motor shaft.
2. An assembly as claimed in claim 1 wherein, said assembly includes a first pulley mounted on a first rolling bearing on said end cover, said first pulley and said first bearing adapted to be radially spaced apart with respect to said shaft.
3. An assembly as claimed in claim 1 wherein, said assembly includes a second pulley integrated in said fan mounted on a second rolling bearing, said second rolling bearing mounted on said shaft at predefined location.
4. An assembly as claimed in claim 1 wherein, said assembly includes a first belt adapted to be looped around said shaft at one end and a first pulley at another end.
5. An assembly as claimed in claim 1 wherein, said assembly includes a second belt adapted to be looped around a radially spaced apart motor-mounted first pulley and a second pulley.
6. A self cooled or forced cooled motor with said improved fan assembly adapted for a motor, said fan assembly comprising:

- a belt and pulley arrangement between a motor shaft at drive or non-drive end of said motor and a fan mounted on said shaft through a rolling bearing, said belt and pulley being driven by said motor shaft and driving said fan, said belt and pulley being of pre-defined dimensions and configuration in accordance with desired fan speed in correlation with rotation of motor shaft.
7. A motor as claimed in claim 1 wherein, said assembly includes a first pulley mounted on a first rolling bearing on said end cover, said first pulley and said first bearing adapted to be radially spaced apart with respect to said shaft.
8. A motor as claimed in claim 1 wherein, said assembly includes a second pulley integrated in said fan mounted on a second rolling bearing, said second rolling bearing mounted on said shaft at predefined location.
9. A motor as claimed in claim 1 wherein, said assembly includes a first belt adapted to be looped around said shaft at one end and a first pulley at another end.
10. A motor as claimed in claim 1 wherein, said assembly includes a second belt adapted to be looped around a radially spaced apart motor-mounted first pulley and a second pulley.