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 end plate for a rotor and a rotor for axially ventilated machines, thereof.
APPLICANTS :
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR (S):
Pandya Ankit and Upadhyay Amarendra; both of Crompton Greaves Limited Machine (M7) Division, D-5, Industrial Area, MP.AKVN, Mandideep - 462046, Madhya Pradesh, India; both 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:
The invention relates to the field of axially ventilated machines.
Particularly, this invention relates to the field of ventilation and cooling of axially ventilated machines.
More particularly, this invention relates to an improved end plate for a rotor and a rotor for axially ventilated machines, thereof.
BACKGROUND OF THE INVENTION:
An 'electrical rotating machine' or a 'rotating electrical machine' is any form of apparatus, equipment, or system which has a rotating member and generates, converts, transforms, or modifies electric power. These include apparatus such as a motor, generator, or synchronous converter.
Essentially all of the world's electric power is produced by rotating electrical generators, and about 70% of this energy is consumed in driving electric motors. Electric machines are electromechanical energy converters; generators convert mechanical energy into electrical energy and motors convert electrical energy into mechanical energy.
An electric machine can be constructed on the principle that a magnet will attract a piece of permeable magnetic material such as iron or magnetic steel. For example, a pole structure along with a magnetic block is allowed to rotate. The magnetic

block will experience a torque tending to rotate it counterclockwise to the vertical direction.
In these examples, if the rotor were allowed to move under the influence of the magnetic forces, it would eventually come to rest at an equilibrium position. Since most applications require continuous motion and constant torque, it is necessary to keep the angle between the rotor magnetic field and the stator magnetic field constant. Thus, in the above examples, the stator magnetic field must rotate ahead of the rotor.
Although there are many variations, the three basic machine types are synchronous, induction, and direct-current machines. These machines may be used as motors or as generators, but the basic principles of operation remain the same. The synchronous machine runs at a constant speed determined by the line frequency. There is an alternating-current winding (normally on the stator) and a direct-current winding (normally on the rotor).
A rotor includes two types of stampings; 1) core or central stampings which essentially form the central body of a rotor and 2) bunch of stacked end stampings which form the end portions of a rotor.
The performance of an 'electrical rotating machine' or a 'rotating electrical machine' is defined by many characteristics. One such characteristic is the cooling quotient and ability of the components of the machine. The rotor temperature needs to be kept in check and below pre-determined threshold parameters for such electrical rotating machines. Efficient cooling of the rotor is an imperative parameter which decides its enhanced working coefficients.

Hence, there is a need for a system and design which induces efficient and
improved heat dissipating characteristics, thereby resulting in improved
performance.
OBJECTS OF THE INVENTION:
An object of the invention is to provide an 'electrical rotating machine' or 'rotating
electrical machine' with improved heat absorbing or heat dissipating
characteristics.
Another object of the invention is to provide an 'electrical rotating machine' or 'rotating electrical machine' with improved heat absorbing or heat dissipating characteristics, thereby resulting in better cooling of the machine.
Yet another object of the invention is to provide enhanced cooling of axially ventilated 'electrical rotating machine' or 'rotating electrical machine'.
Still another object of the invention is to improve the ventilation capabilities of axially ventilated 'electrical rotating machine' or 'rotating electrical machine'.
An additional object of the invention is to provide lower air resistance path to air flowing through the rotor in axially ventilated 'electrical rotating machine' or 'rotating electrical machine'.
Yet an additional object of the invention is to provide a draft for air flow in end laminations of a rotor of axially ventilated 'electrical rotating machine' or 'rotating electrical machine'.

SUMMARY OF THE INVENTION:
According to this invention, there is provided an improved rotor end plate comprising a plurality of stacked end laminations on either side of a substantially cylindrical rotor comprised of main laminations, each of said end laminations and main lamination including vent holes surrounding an axial hole, characterised in that, each vent hole of said stack of end laminations having a pre-defined diameter in accordance with the placement of the end lamination in the stack of end laminations with each end stamping having a vent hole with a diameter that is relatively bigger than the vent hole of an adjacent operatively inward placed end stamping, thereby providing a drafted air flow at the entrance of the vent holes.
According to this invention, there is also provided an axially ventilated machine consisting of a rotor with an improved rotor end plate comprising a plurality of stacked end laminations on either side of a substantially cylindrical rotor comprised of main laminations, each of said end laminations and main lamination including vent holes surrounding an axial hole, characterised in that, each vent hole of said stack of end laminations having a pre-defined diameter in accordance with the placement of the end lamination in the stack of end laminations with each end stamping having a vent hole with a diameter that is relatively bigger than the vent hole of an adjacent operatively inward placed end stamping, thereby providing a drafted air flow at the entrance of the vent holes.
Typically, each of said vent holes includes a protuberance defining an opening and connecting with an outwardly located vent hole of an adjacent end stamping.

Typically, from the operative outer end to the operative inner end laminations on either side of the substantially cylindrical rotor, the diameters of the punched vent holes are progressively reducing.
Typically, each of said end laminations is spot welded to an appropriate adjacent end lamination.
Typically, each of said end laminations includes vent holes wherein the cuts of the vent holes are used to bend said vent holes outwards so as to form a draft for the air inlet.
Typically, each of said end laminations includes vent holes wherein each of said vent holes includes a protuberance defining an opening.
Typically, each of said laminations is made of a metal or other material with a high coefficient of heat transfer.
According to this invention, there is further provided a method for manufacturing an improved rotor end plate comprising a plurality of stacked end laminations on either side of a substantially cylindrical rotor comprised of main laminations, each of said end laminations and main lamination including vent holes surrounding an axial hole, said method comprises the steps of:
a) stacking a pre-defined number of end laminations having a pre-defined diameter in accordance with the placement of the end lamination in the stack of end laminations with each end stamping having a vent hole with a diameter that is relatively bigger than the vent hole of an adjacent operatively inward placed end stamping, thereby providing a drafted air flow at the entrance of the vent holes.

According to this invention, there is still further provided a method for manufacturing a rotor of an axially ventilated machine consisting of an improved rotor end plate comprising a plurality of stacked end laminations on either side of a substantially cylindrical rotor comprised of main laminations, each of said end laminations and main lamination including vent holes surrounding an axial hole, said method comprises the steps of:
A. stacking a pre-defined number of end laminations having a pre-defined diameter in accordance with the placement of the end lamination in the stack of end laminations with each end stamping having a vent hole with a diameter that is relatively bigger than the vent hole of an adjacent operatively inward placed end stamping, thereby providing a drafted air flow at the entrance of the vent holes.
Typically, said method includes a step of spot welding adjacent end laminations with progressively reducing vent hole diameters.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Figure 1 illustrates a front view of a stamping used for rotor construction according to the prior art;
Figure 2 illustrates an isometric view of a rotor constructed using a stack of stampings of Figure 1; and
Figure 3 illustrates a cross-section of the rotor of Figure 2.

The invention will now be described in relation to the accompanying drawings, in which:
Figure 4 illustrates an isometric view of a rotor constructed using a stack or bunch of end stampings defined according to this invention;
Figure 5 illustrates a stack of end stampings in accordance with this invention;
Figure 6 illustrates a cross-section of the rotor of Figure 4; and
Figure 7 illustrates an operative upper portion of a cross-section of the rotor of Figure 4.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Figure 1 illustrates a front view of a stamping used for rotor construction according
to the prior art.
Figure 2 illustrates an isometric view of a rotor constructed using a stack of
stampings of Figure 1.
Figure 3 illustrates a cross-section of the rotor of Figure 2.
Each rotor (200) includes a bunch of stampings which form the core of the rotor. Towards its axial ends, the rotor (200) includes a bunch of end stampings (100) on either side which form the end portion of the rotor. According to the prior art design, each stamping (100) was identical in dimensions as well as with reference to the punched axial hole (12) and punched axially circumferential vent holes (14). There was an intermediate axial hole (12), and vent holes (14) circumferentially

distributed about the axial hole (12). These vent holes and axial holes for each stamping mapped onto each other to form a substantially cylindrical axial hole (22) and a plurality of substantially cylindrical circumferential vent holes (24). The sizes of these holes were uniform for both the main and end laminations for a particular PCD.
As the air enters the motor from the blower unit, it encounters the end stampings. The air enters through the vent holes (14) in the end stamping and passes through the main stampings. In this process, some of air strikes the portions of the end stamping where the vent holes are not present due to which they lose their kinetic energy.
According to this invention, there is provided an improved end plate for a rotor and a rotor for axially ventilated machines, thereof.
Figure 4 illustrates an isometric view of a rotor constructed using a stack or bunch of end stampings defined according to this invention.
Figure 5 illustrates a stack of end stampings in accordance with this invention.
Figure 6 illustrates a cross-section of the rotor of Figure 4.
Figure 7 illustrates an operative upper portion of a cross-section of the rotor of Figure 4.
In accordance with an embodiment of this invention, there is provided a predefined number of end laminations (200), each end lamination having an axially

punched hole (44) of a common pre-defined diameter and further having a plurality of vent holes (42) circumferentially distributed about the axial hole (44), with each vent hole (42) having a pre-defined diameter in accordance with the placement of the end lamination in the stack of end laminations. Each of said vent holes (42) includes a protuberance defining an opening and connecting with an outwardly located vent hole of an adjacent end stamping.
From the operative outer end to the operative inner end laminations (200) on either side of the cylindrical rotor (250), the diameters of the punched vent holes (42) are progressively reducing. This results in a drafted type of end stampings (200) which have a lower air resistance entry path to the vent holes (42).
An additional process is incorporated with respect to the earlier end stampings that shall be included to provide a draft. As shown in the figures 1, 2, and 3, the normal end stamping has normal and matching circular cross sectional vent holes. While in the drafted type of end stampings along with the normal axial hole, cuts protruding outwards from the hole center have been provided as shown in figures 4 and 5 of the accompanying drawings.
After the end stampings have been spot welded to form an end plate, the cuts of the holes are used to bend the holes outwards as shown in figures 6 and 7 of the accompanying drawings so as to form a draft for the air inlet.
This results in no Joss of kinetic energy of the air particles that are targeted towards the vent holes of the motor from the blower unit, thereby resulting in enhanced cooling of the axially ventilated motors.

The technical advancement lies in the provisioning an end plate comprising a plurality of end stampings, each end stamping having a vent hole with a diameter that is relatively bigger than the vent hole of an adjacent inward placed end stamping, thereby providing a drafted air flow at the entrance of the vent holes and lowering the air resistance path, thereby increasing cooling efficiency.
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 rotor end plate comprising a plurality of stacked end laminations on either side of a substantially cylindrical rotor comprised of main laminations, each of said end laminations and main lamination including vent holes surrounding an axial hole, characterised in that, each vent hole of said stack of end laminations having a pre-defined diameter in accordance with the placement of the end lamination in the stack of end laminations with each end stamping having a vent hole with a diameter that is relatively bigger than the vent hole of an adjacent operatively inward placed end stamping, thereby providing a drafted air flow at the entrance of the vent holes.
2. An improved rotor end plate as claimed in claim 1 wherein, each of said vent holes includes a protuberance defining an opening and connecting with an outwardly located vent hole of an adjacent end stamping.
3. An improved rotor end plate as claimed in claim 1 wherein, from the operative outer end to the operative inner end laminations on either side of the substantially cylindrical rotor, the diameters of the punched vent holes are progressively reducing.
4. An improved rotor end plate as claimed in claim 1 wherein, each of said end laminations is spot welded to an appropriate adjacent end lamination.
5. An improved rotor end plate as claimed in claim 1 wherein, each of said end laminations includes vent holes wherein the cuts of the vent holes are used to bend said vent holes outwards so as to form a draft for the air inlet.

6. An improved rotor end plate as claimed in claim 1 wherein, each of said end laminations includes vent holes wherein each of said vent holes includes a protuberance defining an opening.
7. An improved rotor end piate as claimed in claim I wherein, each of said laminations is made of a metal or other material with a high coefficient of heat transfer.
8. An axially ventilated machine consisting of a rotor with an improved rotor end plate comprising a plurality of stacked end laminations on either side of a substantially cylindrical rotor comprised of main laminations, each of said end laminations and main lamination including vent holes surrounding an axial hole, characterised in that, each vent hole of said stack of end laminations having a pre-defined diameter in accordance with the placement of the end lamination in the stack of end laminations with each end stamping having a vent hole with a diameter that is relatively bigger than the vent hole of an adjacent operatively inward placed end stamping, thereby providing a drafted air flow at the entrance of the vent holes.
9. An improved rotor end plate as claimed in claim 8 wherein, each of said vent holes includes a protuberance defining an opening and connecting with an outwardly located vent hole of an adjacent end stamping.
10.An improved rotor end plate as claimed in claim 8 wherein, from the operative outer end to the operative inner end laminations on either side of the substantially cylindrical rotor, the diameters of the punched vent holes are progressively reducing.

11.An improved rotor end plate as claimed in claim 8 wherein, each of said end laminations is spot welded to an appropriate adjacent end lamination.
12. An improved rotor end plate as claimed in claim 8 wherein, each of said end laminations includes vent holes wherein the cuts of the vent holes are used to bend said vent holes outwards so as to form a draft for the air inlet.
13.An improved rotor end plate as claimed in claim 8 wherein, each of said end laminations includes vent holes wherein each of said vent holes includes a protuberance defining an opening.
14.An improved rotor end plate as claimed in claim 8 wherein, each of said laminations is made of a metal or other material with a high coefficient of heat transfer.
15.A method for manufacturing an improved rotor end plate comprising a plurality of stacked end laminations on either side of a substantially cylindrical rotor comprised of main laminations, each of said end laminations and main lamination including vent holes surrounding an axial hole, said method comprising the steps of:
a) stacking a pre-defined number of end laminations having a pre-defined diameter in accordance with the placement of the end lamination in the stack of end laminations with each end stamping having a vent hole with a diameter that is relatively bigger than the vent hole of an adjacent operatively inward placed end stamping, thereby providing a drafted air flow at the entrance of the vent holes.

16.A method as claimed in claim 15 wherein, said method includes a step of spot welding adjacent end laminations with progressively reducing vent hole diameters.
17.A method for manufacturing a rotor of an axially ventilated machine consisting of an improved rotor end plate comprising a plurality of stacked end laminations on either side of a substantially cylindrical rotor comprised of main laminations, each of said end laminations and main lamination including vent holes surrounding an axial hole, said method comprising the steps of:
A. stacking a pre-defined number of end laminations having a predefined diameter in accordance with the placement of the end lamination in the stack of end laminations with each end stamping having a vent hole with a diameter that is relatively bigger than the vent hole of an adjacent operatively inward placed end stamping, thereby providing a drafted air flow at the entrance of the vent holes.
18.A method as claimed in claim 17 wherein, said method includes a step of spot welding adjacent end laminations with progressively reducing vent hole diameters.