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 THE INVENTION
An improved cooling apparatus for totally enclosed fan cooled induction motor .
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTORS
Pangal Sarvesh of Crompton Greaves Ltd, Machine (M7) Division, D-5, Industrial Area, MPAKVN, Mandideep - 462046, Madhya Pradesh, 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 THE INVENTION:
This invention relates to the field of cooling apparatus for motors.
Particularly, this invention relates to the field of an improved cooling apparatus for totally enclosed fan cooled induction motors.
Still particularly, this invention relates to the field of bifurcated cooling systems for totally enclosed fan cooled induction motors.
BACKGROUND OF THE INVENTION:
The motor windings get heated up during its operation due to generation of various heat losses in an induction motor. This invention pertains to an induction motor where an enclosure of totally enclosed type is used. The medium of cooling of the internal parts in a totally enclosed type induction motor is air. The air flow occurs in a pattern such that heat is extracted from the hot portions of stator and rotor and this hot air is then cooled while it passes over tubes of a cooler. Two paths exist inside the motor which are symmetrical in nature.
The path taken by one such air flow across various zones inside the motor (as seen in Figure 1 of the accompanying drawings) is as foilows:
1. A fan (10) delivers air to the stator coil overhang (12) which flows into the cooler zone;
2. Portion of air enters the rotor (14) axially and turns upright through the ducts in between the rotor packs;

3. The air moving ahead cools the stator portion (22), through the stator air guide (20) and gets cooled in the heat exchanger (16); and
4. The cool air now turns again by 180 degrees and a portion of air enters the fan and remainder enters rotor.
The distribution of air to the fan and the rotor is difficult to control. Uneven distribution of air results in the uneven cooling and hence hot spots are created in the circuit. Reference numeral 18 refers to tubes of heat exchanger (16). The movement of hot air and cold air is shown, by arrows.
There is a need for a new and improved baffle design that eliminates this problem and helps in providing the right amount of air to the inlet of the fan and the rotor portions. There is also a need for a baffle design which helps reducing the path velocity losses due to profile of the baffle aiding the flow of air into the rotor.
OBJECTS OF INVENTION:
An object of the invention is to provide to an improved cooling system for totally enclosed fan cooled induction motor in order to reduce in temperature rise of motor.
Another object of the invention is to provide to an improved cooling system for totally enclosed fan cooled induction motor which has a lesser turbulence in the ventilation circuit.

Yet another object of the invention is to provide to an improved cooling system for totally enclosed fan cooled induction motor with no hot spot generation.
Still another object of the invention is to provide to an improved cooling system for totally enclosed fan cooled induction motor which generates lesser turbulence in the ventilation circuit.
An additional object of the invention is to provide to an improved cooling system for totally enclosed fan cooled induction motor which removes bottlenecks in the path towards the air circuit which cools the motor.
Yet an additional object of the invention is to provide to an improved cooling system for totally enclosed fan cooled induction motor which generates lesser noise due to controlled air velocity.
Still another object of the invention is to bifurcate the cold air in rotor circuit as desired / required and overhang which causes effective cooling in rotor and eliminates temperature rise or reduction in temperature of rotor.
Another object of the invention is to avoid / eliminate hot spot generation effectively and separately by cooling the overhang.
Yet another object of the invention is to streamline air path thereby reducing noise level.

SUMMARY OF THE INVENTION:
According to this invention, there is provided an improved cooling apparatus for totally enclosed fan cooled induction motor having rotor core, stator core, stator overhang coils, and ducts, said cooling system comprises:
a. baffle means adapted to be located on an air guiding means for
guiding movement of air through said air guiding means;
b. rotating shaft adapted to mount said baffle means; and
c. internal separator means on said baffle means adapted to split
guided air into pre-defined directions for cooling;
Typically, said baffle means is an aerodynamically shaped baffle means.
Typically, said baffle means includes internal separator means adapted to channel air to said rotor core and into said ducts.
Typically, said baffle means includes internal separator means adapted to channel air to said stator coil overhang.
Typically, said internal separator means is a substantially co-axially located cylindrical projection.
Typically, said baffle means is mounted directly on said rotating shaft.
Typically said apparatus includes a fan adapted to circulate flow of air through said air guide.

Typically, said apparatus includes a fan mounted on said shaft in order to circulate air through said air guide.
Typically, said fan is located on said shaft in accordance with pre-defined cooling parameters.
Typically, said fan is located on said shaft in accordance with pre-defined motor parameters.
Typically, said apparatus includes two fans mounted on said shaft in order to circulate air through said air guide.
Typically, each of said baffle means is correspondingly located before each of said fan element.
Typically, said internal separator means includes a cylindrical hub coaxial with said baffle means, and connected to said baffle means with radial spokes between exterior perimeter of said hub and interior perimeter of said baffle means.
Typically, baffle means is a circular disc with a substantially co-axially located cylindrical projection.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Figure 1 illustrates a cooling system along with air guide, of the prior art, for heat exchangers along with stator, rotor, stator overhang, fans, rotor shaft.

The invention will now be described in relation to the accompanying drawings, in which:
Figure 2 illustrates a schematic of the cooling system, having baffle means with internal separator, along with associated heat exchanger assembly, stator, rotor, stator overhang, fans, and shaft.
Figure 3 illustrates an isometric front view and isometric back view of a first embodiment of said baffle means of Figure 2;
Figure 4 illustrates a side view of a first embodiment of said baffle means of Figure 2;
Figure 5 illustrates an isometric front view and isometric back view of a second embodiment of said baffle means of Figure 2; and
Figure 6 illustrates a side view of a second embodiment of said baffle means of Figure 2.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Figure 2 illustrates a schematic of the cooling system along with associated heat exchanger assembly, stator, rotor, stator overhang, fans, and shaft.
According to this invention, there is provided an improved cooling system for totally enclosed fan cooled induction motor by providing

baffle system (50) on rotating shaft (52) to balance the supply of cooling air to the stator overhang coils (54), rotor core (5.6) and stator core (58).
While high power induction machines are designed, the rotor core length is very large. The rotor core comprises stampings that are stacked on one over the other and discrete packs of such placements are laid in a row separated by ducts. These ducts serve as fan vanes and help in increasing the velocity of the air that extracts heat. When many such ducts are used, the suction of air created by the ducts is greater than the suction created by the fan (60). These result in less amount of air that enters the fan mounted on the shaft which is used to cool the stator coil overhang.
In accordance with an embodiment of this invention, there is provided a baffle which has an aerodynamic profile having another internal separator. Typically, the internal separator divides the air entering the baffle into two portions. One portion is such that it further enters the rotor core (56) and into the ducts and the other portion is such that it is used by the fan (60) mounted on the fan and into the stator coil overhang (54). The baffle dimensions are appropriately designed as per the varying requirements of air to the internal parts of the induction motor. This separation of cool air results in better cooling of the motor and reduces noise generated in the internal circuit of air flow. Due to the aerodynamic construction of the baffle, the turbulence of air is greatly reduced. The baffle introduced helps reducing the number of variations in the rotor circuit design since the guiding baffle (50) is mounted directly on the shaft (52). Reference numeral 62 refers to a stator air guide. Reference numeral 64 refers to a heat exchanger. Reference numeral 66 refers to tubes of heat exchanger (64).

Typically, Epoxy based molded component is used as construction material for baffle. The (aerodynamic) shape of the baffle is important for effective bifurcation of cold air. The side of the baffles should have smooth curvature, for an effective aerodynamic design. Smooth curvatures streamline the airflow without resistance and direct the air in desired direction.
In accordance with another embodiment of this invention, there is provided a controlled distribution means for providing controlled distribution of air to the rotor ducts and the stator coil of an induction motor.
In accordance to the invention, an improved cooling system is provided for totally enclosed fan cooled induction motor, where different internal parts and portions of the induction motor gets heated up during normal operation at load. The heat thus generated at rotor core, rotor conductor, stator core, stator conductor and the stator coil overhang needs to be cooled. Two fans are installed on the rotating shaft in order to cool the aforementioned parts. Two fans installed circulate air from the inside of the motor to the cooler portion where it dissipates the heat. While doing so, it creates two circuits of air circulation known as twin circuit cooling. The invention introduces one baffle before each of the fan element of the cooling circuit in order to control the amount of cool air reaching different portions of the rotor and stator. The separation of cool air helps the differential heat extraction rates while keeping the velocity of air flowing over the parts sufficient to overcome losses at the cooling zones.

Typically, position of internal fan for cooling will decide the quantity of air to be let in and position of the baffle. The position varies according to capacity of the motor.
The movement of air is shown, by arrows.
Drawback associated with the prior art due to heat generation causes heat loss. But, the apparatus of the current invention reduces losses in the motor as there is better heat dissipation.
Figure 3 illustrates an isometric front view and isometric back view of a first embodiment of said baffle means of Figure 2. Figure 4 illustrates a side view of a first embodiment of said baffle means of Figure 2. Figure 5 illustrates an isometric front view and isometric back view of a second embodiment of said baffle means of Figure 2. Figure 6 illustrates a side view of a second embodiment of said baffle means of Figure 2. Reference numeral 82 refers to air guide. Reference numeral 84 refers to spoke. Reference numeral 86 refers to hub. The spoke and hub form the internal separator means.

We claim:
1. An improved cooling apparatus for totally enclosed fan cooled
induction motor having rotor core, stator core, stator overhang coils,
and ducts, said cooling system comprising:
a. baffle means adapted to be located on an air guiding means for
guiding movement of air through said air guiding means;
b. rotating shaft adapted to mount said baffle means; and
c. internal separator means on said baffle means adapted to split
guided air into pre-defined directions for cooling;
2. An apparatus as claimed in claim 1 wherein, said baffle means is an aerodynamic ally shaped baffle means.
3. An apparatus as claimed in claim 1 wherein, said baffle means includes internal separator means adapted to channel air to said rotor core and into said ducts.
4. An apparatus as claimed in claim 1 wherein, said baffle means includes internal separator means adapted to channel air to said stator coil overhang.
5. An apparatus as claimed in claim 4 wherein, said internal separator means is a substantially co-axially located cylindrical projection.
6. An apparatus as claimed in claim 4 wherein, said internal separator means includes a cylindrical hub co-axial with said baffle means, and

connected to said baffle means with radial spokes between exterior perimeter of said hub and interior perimeter of said baffle means.
7. An apparatus as claimed in claim 1 wherein, said baffle means is mounted directly on said rotating shaft.
8. An apparatus as claimed in claim 1 wherein, said apparatus includes a fan adapted to circulate flow of air through said air guide.
9. An apparatus as claimed in claim 1 wherein, said apparatus includes a fan mounted on said shaft in order to circulate air through said air
guide.
10.An apparatus as claimed in claim 9 wherein, said fan is located on said shaft in accordance with pre-defined cooling parameters.
1 l.An apparatus as claimed in claim 9 wherein, said fan is located on said shaft in accordance with pre-defined motor parameters.
12.An apparatus as claimed in claim 1 wherein, said apparatus includes two fans mounted on said shaft in order to circulate air through said air guide.
13.An apparatus as claimed in claim 1 wherein, each of said baffle means is correspondingly located before each of said fan element.

14. An apparatus as claimed in claim 1 wherein, said baffle means is a circular disc with a substantially co-axially located cylindrical projection.