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
A motor frame providing ease of commutation, and a motor, thereof.
APPLICANT(S):
Crompton Greaves Limited, CG House, 6th Floor, Dr. Annie Besant Road, Worli, Mumbai - 400030, Maharashtra, India; an Indian Company.
INVENTOR (S):
Pandya Ankit and Upadhyay Amarendra; both of Crompton Greaves Limited, Machine (M7) Division, Industrial Area, MPAKVN, 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:
This invention relates to the field of electrical and electronics engineering.
Particularly, this invention relates to motors and motor assemblies.
Specifically, this invention relates to a motor frame providing ease of commutation, and a motor, thereof.
BACKGROUND OF THE INVENTION:
A motor for electrical purposes, i.e. an electric motor, is a device which converts electrical energy to mechanical energy. For industrial use, the ratings of motor may typically be very high. They may be placed in housings or frames. It contains two main components; stator and rotor. The rotor is the non-stationary part of a rotary motor, which rotates because the wires and magnetic field of the motor are arranged so that a torque is developed about the rotor's axis. The stator is the stationary part of a rotor system.
A commutator is a rotary electrical switch in certain types of electric motors or electrical generators that periodically reverses the current direction between the rotor and the external circuit. A commutator is a common feature of a DC motor. This commutator consists of a number of segments of copper or of other suitable electrical conducting substance place together in the form of a ring with a sheet of electrical insulating substance between every two adjacent segments. The segments

or bars of a commutator are held in position by an undercut clamping ring of an insulating material such as mica.
In a DC motor there are main poles and inter-poles. The main poles are used for generation field magnetization which interacts with the armature to rotate the machine. The inter-poles are used to reduce the effect of armature reaction and hence improve commutation in DC motors. The air gap between these inter-poles and rotor is important for the performance of the machine. This air gap is maintained with the addition or removal of liners at the bottom of the poles.
Usually, during prototype manufacturing of a particular design of DC motor, the most commonly faced problem is that of poor commutation. Because of poor commutation, heavy sparking and even shooters are observed at high current levels. This poor commutation occurs due to the shift in the black band zone (no-sparking zone) from its requisite position. To correct the shift of the black band zone, the magneto-motive force (mmf) required by the inter-poles has to be corrected. The mmf required either has to be increased or decreased depending on the shift the black band zone. For confirming the exact requirement a special type of test is carried out namely "Black Band Test". After carrying out the test, it can be ascertained that whether the mmf of the inter-pole has to be increased or decreased. Mmf depends upon the Ampere-turns (AT) of the inter-poles. Now for a particular design where the motor has already been manufactured, neither the Amperes nor the turns can be changed. So how can the problem of incorrect commutation due to improper mmf of the inter-poles be corrected. The solution lies in the fact that the mmf is depended on the air gap of the inter-pole. So by adjusting the air gap the actual mmf fed by the inter-poles can also be adjusted. The adjustment of the air gap can be done by changing the liner combination of the inter-poles. These liners are placed between the pole brick of the inter-pole and the

frame of the DC Motor on to which the pole bricks are mounted. But for changing the liner combination the motor has to be dismantled first. Then, the connections of the inter-poles with the brush holder have to be opened and finally the mounting bolts of the inter-poles have to be removed.
The process is repeated until a suitable combination is established wherein desired commutation level is achieved. This situation may arise at customer site during installing and commissioning which may not be able to resolve at the site. Moreover, liners are installed on poles using bolts, and these liners are custom-designed.
As the poles are located in the interior the motor, the motor is required to be disassembled to change the liner combination. And in order to obtain a correct custom designed fit, multiple liner configurations may need to be removed and installed. According to the prior art, this warrants motor disassembly, each time, and therefore, a higher amount of time for testing.
PRIOR ART:
JP2004104878 discloses a gap in the diametrical direction of the brush inspection window. However, it does not provide for insertion of removal of liners.
US2003161740 discloses use of liners in motor, especially in motor air gaps.
US4922146 document discloses use of air gaps. However, they are for cooling purposes and not for liners.
US4668139 discloses spacers for in situ chamfering of commutator segments.

US3 543067 describes an insulating support structure for commutating field coils employed in electric machines and insulating support structure placed between poles and frames. The use of rigid, comb like insulating structures secured to the sides of the pole piece body with the turns held in place between teeth or lateral projections of the comb like structures.
US4780953 describes a roll-formed, submersible electric motor for a well pump wherein motor laminations are compressed between an end ring and a coupling base while an outer metallic shell is formed to grippingly engage the ring and base, thereby maintaining the components in assembled relationship. The coupling base has fluid conduits for circulation of coolant to an armature bearing, and the base also has structure for contacting one end of a stack of pump stages and maintaining the latter in aligned relationship to the pump drive shaft.
Still there is a need exist that air gap between these inters poles and rotor is important for the performance of the inter-poles.
OBJECTS OF THE INVENTION:
An object of the invention is to provide for changing of liner combination in a motor without it being dismantled.
Another object of the invention is to change liners located behind poles in a motor without the motor being dismantled.
Yet another object of the invention is to allow different configurations of liners in a reduced time period.

Still another object of the invention is to provide an improved time span in remedial procedures of changes in motor assembly.
SUMMARY OF THE INVENTION:
According to this invention, there is provided a motor frame providing ease of commutation, said motor frame comprises:
• at least two laterally located cut-outs on operative top surface of said motor
frame, said cut-outs being located in a pre-defined manner at pre-defined
locations for allowing insertion of self-aligning liners merely by loosening
of mounting bolts of pole bricks.
According to this invention, there is also provided a motor located within a motor frame providing ease of commutation, said motor frame comprises:
• at least two laterally located cut-outs on operative top surface of said motor
frame, said cut-outs being located in a pre-defined manner at pre-defined
locations for allowing insertion of self-aligning liners merely by loosening
of mounting bolts of pole bricks.
Typically, said cut-outs are located just before starting of liners such that the liners can pass through it to the desired position under said frame.
Typically, said motor frame comprising at least a guide in order to guide said liners through axial length of said frame when properly inserted through said cut-outs.
Typically, said liners are self-locking liners allowing themselves to be guided with the help of a guide in said motor frame.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
Figure la illustrates an exploded view of pole and liner assembly in a motor;
Figure lb illustrates a liner assembly between a pole brick and motor frame; and
Figure lc illustrates a zoomed-in view of the liner assembly.
The invention will now be described in relation to the accompanying drawings, in which:
Figure 2 illustrates a motor frame with cut-outs for liner insertion;
Figure 3 illustrates a loosened pole assembly; and
Figure 4 illustrates a liner insertion in the loosened pole assembly of Figure 3 using the motor frame with cut-outs of Figure 2.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
The existing arrangement of the liner assembly for main field pole and the inter-poles is as shown in the figure 1 (a, b and c). As is visible in figure 1, of the accompanying drawings, the liner (12) combination for the poles (14) is placed in between the pole brick of the field windings (16) and the motor frame of the motor. In case, during testing of a particular motor, desired commutation levels are not achieved, then black band test has to be carried out to achieve the desired level of commutation. To achieve the desired level of commutation the liner combination of the inter-poles has to be adjusted. For adjusting the liner combination, complete dismantling of the motor has to be carried out along with dismounting of the poles from the frames. If the process is not successful in its first attempt, then the process is to be repeated until the desired level of commutation is achieved. This is a very tedious process as it involves a lot of man hours. According to the prior art, in a typical scenario, 2 or 3 changes of liner configurations are required before optimum commutation is achieved. This may take up to a week of effort and time wastage. Also, repetitive dismantling of motor is also not suitable for the health of the bearings.
To eliminate the need for dismantling of the machine and the field poles of the motor, there is a need of a motor frame that allows for easier and removal of liners.
According to this invention, there is provided a motor frame providing ease of commutation.
Figure 2 illustrates a motor frame with cut-outs for liner insertion.

In accordance with an embodiment of this invention, there are provided at least two laterally located cut-outs (22) on the operative top external surface of motor frame (20). The provisioning of these cut-outs in a pre-defined manner at predefined locations allow for insertion of self aligning liner combinations merely by loosening of mounting bolts of pole bricks. The cut-outs are so designed and located that the liners (12) can pass through it to the desired position under the frame. The two laterally located cut-outs are provided so that each half of the modified liner can pass through each of the cut-outs, respectively.
In accordance with another embodiment of this invention, there is provided a guide in order to guide the liners through the axial length of the frame when properly inserted through the cut-outs.
Figure 3 illustrates a loosened pole assembly.
Prior to the insertion of the liner assembly, the poles (14) have to be loosened to allow for space for the liner assembly to pass in between the motor frame and pole brick of the inter pole assembly. As soon as mounting bolts of the inter-pole assembly are loosened, the field pole assembly loses its contact with the frame and hangs from the frame through the loosened mounting bolts. Now, each half of the modified liners of the existing liner combination can be removed through the cutouts in the magnet frame. Please note that the modified liners shall have provision for pulling it out from its location.
Figure 4 illustrates a liner insertion in the loosened pole assembly of Figure 3 using the motor frame with cut-outs of Figure 2. After the existing liner combination has been removed, the new liner (12) combination can now be inserted through the cutouts (22) in the frame (20).

In accordance with an embodiment of this invention, the liner of this invention is provisioned for self-locking and allows itself to be guided with the help of the afore-mentioned guide into the motor frame.
As soon as the modified liner combination is in its desired location the mounting bolts of the field pole assembly is tightened to the specified torque levels and the motor is now ready for testing again.
The present invention is simple to design and economic in terms of man power relating to motors having commutation problems and requiring replacement of liners. The process involves loosening of the inter-poles to allow a gap between the frame and pole surface. And with the help of accessibility from the frame cutout, liners could be changed as required.
The INVENTIVE STEP of the proposed invention lies in the provisioning of cut-outs in a motor frame in an advantageous manner and provisioning of modified liners to be inserted and pulled out through the cut-outs. The liners, of this proposed invention, have provision to self lock and be guided along the way through the cut-out in the frame.
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 motor frame providing ease of commutation, said motor frame
comprising:
• at least two laterally located cut-outs on operative top surface of said
motor frame, said cut-outs being located in a pre-defined
manner at pre-defined locations for allowing insertion of self-aligning liners merely by loosening of mounting bolts of pole bricks.
2. The motor frame as claimed in claim 1, wherein said cut-outs are located just before starting of liners such that the liners can pass through it to the desired position under said frame.
3. The motor frame as claimed in claim 1, wherein said motor frame comprising at least a guide in order to guide said liners through axial length of said frame when properly inserted through said cut-outs.
4. The motor frame as claimed in claim 1, wherein said liners are self-locking liners allowing themselves to be guided with the help of a guide in said motor frame.
5. The motor frame as claimed in claim 1, wherein said motor frame comprising removable covers over said cut-outs.
6. A motor located within a motor frame providing ease of commutation, said motor frame comprising:

• at least two laterally located cut-outs on operative top surface of said
motor frame, said cut-outs being located in a pre-defined
manner at pre-defined locations for allowing insertion of self-aligning liners merely by loosening of mounting bolts of pole bricks.
7. The motor as claimed in claim 6, wherein said cut-outs are located just before starting of liners such that the liners can pass through it to the desired position under said frame.
8. The motor as claimed in claim 6, wherein said motor frame comprising at least a guide in order to guide said liners through axial length of said frame when properly inserted through said cut-outs.
9. The motor as claimed in claim 6, wherein said liners are self-locking liners allowing themselves to be guided with the help of a guide in said motor frame.
10. The motor as claimed in claim 6, wherein said motor frame comprising removable covers over said cut-outs.