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
Hoe-shaped stator spacers and stators / motors thereof
APPLICANTS:
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR(S):
Reddy Bijjam V. Krishna, Paramane Sachin Bhimarao and Dhavileswarapu Srinivas; all of Analytics Centre, Global R&D Centre, Crompton Greaves Ltd., Kanjur Marg (East), Mumbai - 400 042, Maharashtra, 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 motors, generators, alternators.
Particularly, this invention relates to stators in motors.
Still particularly, this invention relates to stator spacers.
More particularly, this invention relates to hoe-shaped stator spacers and stators / motors thereof.
Background of the Invention:
A motor is electrical equipment that translates electrical energy into mechanical energy. A motor comprises stator, rotor, and commutator. A stator is the stationary part while the rotor is a rotating part of an electric motor.
A stator of a motor includes bars and stator spacers between the bars.
Presently, a stator spacer with I-cross section is used. There is an air gap between the rotor and stator. As the rotor rotates, the rotating action causes centrifugal air to interact with the stator. The stator spacers are designed in order to allow passage of this air, through its sides.
However, it does not have any guided surfaces for uniform and smooth entry of flow from rotor to stator parts. This stator spacer guides the flow only in one side

exposed to stampings. Therefore, the other side surface temperatures are higher and which in turn reduces the thermal efficiency of the motor.
Typically, the motors are designed by electrical engineers. Calculations and parameters relating to fluid flow, pressure drop and heat transfer and time have not been keenly observed or inferred in a rotor stator arrangement. Furthermore, general thinking is to increase the motor size or to increase the number of spacers to improve the air flow but may not look at other aspects to reduce the resistance of air flow, uniform distribution of air, enhancement in heat transfer.
Furthermore, most of the engineers look at the stampings and spacers as a separate entity not as a combined configuration. Moreover, these effects are studied by only CFD analysis as the experimentation will be difficult and costly for such type of design.
Prior Art:
US6504273B2 discloses the concept of using an adjustable baffle secured to the space block with fastening assembly for controlling the air flow.
US6777836B2 discloses space blocks itself forming a wavy longitudinal profile with an alternating pattern of peaks and valleys.
Also, patent documents disclosed scoop structured spacers (US6495943) and reentrant space block configuration with a contoured rearward facing (US6617749)

which are arranged between the end windings of rotor for achieving the advantage of enhanced rotor cavity heat transfer and improved cooling of rotors.
None of the above-mentioned patent documents disclose embodiment, techniques, methods for increase in air exposure to stamping surfaces on both sides of spacer or better reliability and reduction in maintenance or reduction noise of motor and power consumption.
Objects of the Invention:
An object of the invention is to provide an improved stator design.
Another object of the invention is to provide a stator spacer adapted to be fitted in a stator, said spacer guiding air effectively.
Yet another object of the invention is to provide a stator spacer adapted to be fitted in a stator, said spacer guiding air uniformly.
Still another object of the invention is to provide a motor with reduced maintenance.
An additional object of the invention is to provide a motor with less noise.
Yet an additional object of the invention is to provide a motor with better heat dissipating characteristics.

Summary of the Invention:
According to this invention, there is provided a hoe-shaped stator spacer comprising:
an elongate member with an I-shaped cross section, said elongate member consisting of a central rectangular column flanked by a pair of side rectangular columns parallel to each other, length-wise, and placed laterally orthogonal to the width-wise edges of said central column; said pair of side rectangular columns touching said central rectangular columns at their substantial mid-length and mid-width central axis respectively,
characterized in that, baffle means protruding angularly from an operative rotor side end of said I-shaped cross section elongate member, said baffle adapted to allow entry of air in the gap between said baffle and said elongate member and to further allow substantially balanced amount of air in the gap between said stator spacer and an adjacent stator stamping.
According to this invention, there is also provided a stator having a plurality of stator stampings and stator spacers radially dispersed in an alternating fashion wherein, said stator spacer being a hoe-shaped stator spacer comprises: an elongate member with an I-shaped cross section, said elongate member consisting of a central rectangular column flanked by a pair of side rectangular columns parallel to each other, length-wise, and placed laterally orthogonal to the width-wise edges of said central column; said pair of side rectangular columns touching said central rectangular columns at their substantial mid-length and mid-width central axis respectively,

characterized in that, baffle means protruding angularly from an operative rotor side end of said I-shaped cross section elongate member, said baffle adapted to allow entry of air in the gap between said baffle and said elongate member and to further allow substantially balanced amount of air in the gap between said stator spacer and an adjacent stator stamping.
According to this invention, there is further provided a motor having at least a stator and at least a rotor, said stator having a plurality of stator stampings and stator spacers radially dispersed in an alternating fashion wherein, said stator spacer being a hoe-shaped stator spacer comprises:
an elongate member with an I-shaped cross section, said elongate member consisting of a central rectangular column flanked by a pair of side rectangular columns parallel to each other, length-wise, and placed laterally orthogonal to the width-wise edges of said central column; said pair of side rectangular columns touching said central rectangular columns at their substantial mid-length and mid-width central axis respectively,
characterized in that, baffle means protruding angularly from an operative rotor side end of said I-shaped cross section elongate member, said baffle adapted to allow entry of air in the gap between said baffle and said elongate member and to further allow substantially balanced amount of air in the gap between said stator spacer and an adjacent stator stamping.
Typically, said baffle means (mentioned above) is a substantially rectangular plate having a first portion of the plate, at one of its edge on one side, mate with the width-wise edge of a first side column from said pair of side rectangular columns of said elongate member, and a second portion of the plate, at the other edge on the

same side, mate with the width-wise edge of said second side column from said pair of side rectangular columns of said elongate member.
Additionally, said baffle means may be a holed baffle means comprising at least a hole in said plate to allow passage of air.
Brief Description of the Accompanying Drawings:
Figure 1 illustrates an existing stator assembly of the prior art.
Figure 2 illustrates a stator spacer of the prior art.
Figure 3 illustrates a CFD analysis of the stator assembly with the stator spacer of the prior art.
The invention will now be described in relation to the accompanying drawings, in which:
Figure 4 illustrates a stator spacer;
Figure 5 illustrates a CFD analysis of the stator assembly with the stator spacer of Figure 4; and
Figure 6 illustrates an additional alternative embodiment of a stator spacer of Figure 4.

Detailed Description of the Accompanying Drawings:
Figure 1 illustrates an existing stator assembly of the prior art which includes stator stampings (12) and stator spacers (14). A portion of a rotor (16) is shown.
Figure 2 illustrates a stator spacer (14) of the prior art.
Figure 3 illustrates a CFD analysis of the stator assembly with the stator spacer of the prior art. It shows Velocity contour and vectors with existing stator spacer (14). Blue coloured region shows the low velocity region whereas red colour region shows high velocity, and therefore low temperature portion. There is a higher temperature gradient on either side of the stator spacer. An operative first side (15) records a bluish profile depicting a relatively lesser flow of air from that side. An operative right side (17) records a greenish-yellowish profile depicting a relatively higher flow of air from that side. This imbalance in air flow makes the stator assembly subject to stress and deterioration over a span of time.
According to this invention, there is provided a hoe-shaped stator spacer and stator thereof.
Figure 4 illustrates a stator spacer (30) of this invention.
In accordance with an embodiment of this invention, there is provided an elongate member with an I-shaped cross section. Typically, the elongate member is a central rectangular column (32) flanked by a pair of side rectangular columns (34, 36) parallel to each other, length-wise, and placed laterally orthogonal to the width-

wise edges of said central column. The pair of side rectangular columns touches the central rectangular columns at their substantial mid-length and mid-width central axis respectively. The I-shaped cross section elongate member is characterized by a baffle means (38) protruding angularly from an operative rotor side end of said I-shaped cross section elongate member.
Preferably, the baffle means is a substantially rectangular plate. A first portion of the plate, at one of its edge on one side, mates with the width-wise edge of a first side column from said pair of side rectangular columns, while a second portion of the plate, at the other edge on the same side, mates with the width-wise edge of said second side column from said pair of side rectangular columns.
The defined configuration of the spacer according to this invention is such that there is gap provided in between the edge which mates with portions of the spacer and the central column of the spacer.
Air flowing through the motor assembly or as dispersed by the rotor assembly finds easy channels through the gaps mentioned above and as shown by the dotted arrows in Figure 4 of the accompanying drawings. Earlier, more air flowed through the side where the baffle is now placed due to the centrifugal force exerted on the air by the rotating rotor. The other side of the spacer recorded lower velocity of air.
Ease of flow of air, without obstruction, lessens turbulence and vortex formation, thereby reducing resistance and chances of heating up associated assembly.

This 'hoe shaped' stator spacer is placed in between bunch of stampings and used for better flow distribution whose arrangement is determined according to direction of rotation of the rotor to improve the thermal performance of motor. The stator spacers and stator stampings are radially dispersed in the stator assembly of the motor and form a full circle. As the rotor rotates, it disperses air, which due to the centrifugal force attains a curved path and finds exit paths through the stator, especially through the gaps provided in the stator spacer.
This configuration allows flow of air into the gap between the stator stampings, catches more uniform and better air flow distribution, mass flow rate enhancement; reduce power consumption and noise of motor.
The most common dictum being followed according to prior art design considerations is that it is important that air should be exposed to maximum possible area of stator stampings for better flow distribution and heat dissipation. In the current invention, better air flow distribution can be achieved by providing an inclined surface (due to baffle) at one end (rotor side) of the I-section spacer in the flow entry side of the stator. This hoe shaped spacer design provides the path for uniform flow on either side of the spacer and remains in contact with the stampings surfaces during the operation of the motor compared to the existing design. To enhance the heat transfer from the stator stampings it is needed that air should be exposed to more surface area of the stator stampings. Therefore, the cooling of the motor can be increased for better reliability and reduction in maintenance.

Moreover, smoother and uniform entry of flow of air around the spacer and in between the stampings will reduce motor noise. Also, due to this invention, weight of motor can be reduced which in turn will help to reduce the cost of motor. This will lead to higher heat transfer coefficients and higher cooling capacity in stampings thereby increased rating of motor for same size or lower size of motor for same rating.
The use of this 'hoe shaped' stator spacer design in between the bunch of stampings, provides more uniform, higher mass flow rate of air and guides flow path thereby improving flow distribution without increase in pressure drop.
Figure 5 illustrates a CFD analysis of the stator assembly with the stator spacer of Figure 4. It shows velocity contour and vectors with hoe shaped spacer. The bluish profile shows relatively lesser velocity air about the stator spacer and in communication with the stator stampings. Hence, it shows uniform distribution of air and improved velocity distribution as compared to the CFD analysis depicted in Figure 3 (prior art) of the accompanying drawings
Figure 6 illustrates an additional alternative embodiment of a stator spacer of Figure 4. In order to still balance the amount of air being dispersed on either side of the spacer, air holes (42) are provided in the baffle, thereby ensuring that the baffle does not block more air on one side.
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. A hoe-shaped stator spacer comprising:
an elongate member with an I-shaped cross section, said elongate member consisting of a central rectangular column flanked by a pair of side rectangular columns parallel to each other, length-wise, and placed laterally orthogonal to the width-wise edges of said central column; said pair of side rectangular columns touching said central rectangular columns at their substantial mid-length and mid-width central axis respectively,
characterized in that, baffle means protruding angularly from an operative rotor side end of said I-shaped cross section elongate member, said baffle adapted to allow entry of air in the gap between said baffle and said elongate member and to further allow substantially balanced amount of air in the gap between said stator spacer and an adjacent stator stamping.
2. A stator spacer as claimed in claim 1 wherein, said baffle means is a substantially rectangular plate having a first portion of the plate, at one of its edge on one side, mate with the width-wise edge of a first side column from said pair of side rectangular columns of said elongate member, and a second portion of the plate, at the other edge on the same side, mate with the width-wise edge of said second side column from said pair of side rectangular columns of said elongate member.
3. A stator spacer as claimed in claim 1 wherein, said baffle means is a holed baffle means comprising at least a hole in said plate to allow passage of air.

4. A stator having a plurality of stator stampings and stator spacers radially
dispersed in an alternating fashion wherein, said stator spacer being a hoe-
shaped stator spacer comprising:
an elongate member with an I-shaped cross section, said elongate member consisting of a central rectangular column flanked by a pair of side rectangular columns parallel to each other, length-wise, and placed laterally orthogonal to the width-wise edges of said central column; said pair of side rectangular columns touching said central rectangular columns at their substantial mid-length and mid-width central axis respectively,
characterized in that, baffle means protruding angularly from an operative rotor side end of said I-shaped cross section elongate member, said baffle adapted to allow entry of air in the gap between said baffle and said elongate member and to further allow substantially balanced amount of air in the gap between said stator spacer and an adjacent stator stamping.
5. A stator as claimed in claim 4 wherein, said baffle means is a substantially
rectangular plate having a first portion of the plate, at one of its edge on one
side, mate with the width-wise edge of a first side column from said pair of side
rectangular columns of said elongate member, and a second portion of the plate,
at the other edge on the same side, mate with the width-wise edge of said
second side column from said pair of side rectangular columns of said elongate
member.

6. A stator spacer as claimed in claim 4 wherein, said baffle means is a holed baffle means comprising at least a hole in said plate to allow passage of air.
7. A motor having at least a stator and at least a rotor, said stator having a plurality of stator stampings and stator spacers radially dispersed in an alternating fashion wherein, said stator spacer being a hoe-shaped stator spacer comprising: an elongate member with an I-shaped cross section, said elongate member consisting of a central rectangular column flanked by a pair of side rectangular columns parallel to each other, length-wise, and placed laterally orthogonal to the width-wise edges of said central column; said pair of side rectangular columns touching said central rectangular columns at their substantial mid-length and mid-width central axis respectively,
characterized in that, baffle means protruding angularly from an operative rotor side end of said I-shaped cross section elongate member, said baffle adapted to allow entry of air in the gap between said baffle and said elongate member and to further allow substantially balanced amount of air in the gap between said stator spacer and an adjacent stator stamping.
8. A motor as claimed in claim 7 wherein, said baffle means is a substantially
rectangular plate having a first portion of the plate, at one of its edge on one
side, mate with the width-wise edge of a first side column from said pair of side
rectangular columns of said elongate member, and a second portion of the plate,
at the other edge on the same side, mate with the width-wise edge of said
second side column from said pair of side rectangular columns of said elongate
member.

9. A stator spacer as claimed in claim 7 wherein, said baffle means is a holed baffle means comprising at least a hole in said plate to allow passage of air.