FORM 2
THE PATENT ACT, 1970
(39 of 1970)
&
THE PATENT RULES, 2003
COMPLETE SPECIFICATION (See Section 10 and Rule 13)
TITLE OF INVENTION: ROTOR CONSTRUCTION FOR DIRECT LINE OPERATED PERMANENT MAGNET SYNCHRONOUS MOTOR
APPLICANT(S): SHAKTI PUMPS (INDIA) LTD.
PREAMBLE
The following specification particularly describes nature of the invention.

Field of the invention
The present invention relates to an energy efficient motor. More particularly, it relates to a construction of rotor employed in high energy efficient motor.
Background of the invention
The construction of line operated energy efficient motor wherein conductor bars placed in outermost side & magnet placed at inner peripheral side of the of the stack, thus it reduces the inner diameter of the stack, consequently it reduces the outer diameter of the shaft, as a result further reduction in strength of the shaft, which leads to torsional bending of the shaft at high torsional load conditions at the time of starting or sudden load changes.
Such a motor has been disclosed in US 4358696 B1. Said invention relates to a permanent magnet rotor configuration which produces four magnetic poles utilizing two sets of symmetrically-disposed permanent magnets. The slots carrying the magnets exhibit a truncated V-shaped configuration, extending from points on the periphery of the rotor to meet the ends of a straight, central portion which lies parallel to a tangent to the rotor shaft. A short magnetic bridge interrupts the center of each slot, the slots being disposed generally symmetrically upon opposite sides of the rotor shaft.

Such a motor is disclosed in US 4922152. Said invention relates to a rotor lamination for a permanent magnet synchronous machine. The rotor lamination can be used for a two, four or eight pole synchronous machine. The orientation of the permanent magnets determines the number of poles of the machine. The lamination can also include openings adapted to contain conductors used to bring a synchronous motor up to synchronous speed as an induction motor. Such a motor is disclosed in US 6844652 B1. Said invention relates to a rotor structure of line-start permanent magnet (LSPM) synchronous motor that includes a shaft; four fan-shaped magnetic poles each having a first eccentric circular arcs of the surface of the magnetic poles which has a center O1 that is offset from the center O of the rotor with an offset length OS1 and which makes the maximum thickness of the air gap roughly two to five times as much as the minimum thickness of the air gap; four permanent magnets disposing in the inner loop of each of the fan-shaped magnetic poles. A plurality of pear-shaped conductor slots disposing in equal spaces in the outer loop of the rotor in each of the fan-shaped magnetic poles and orienting in radial direction having O1 as the center for forming a squirrel cage winding; as well as four recesses at the midpoint of the first eccentric circular arcs of the surface of the magnetic poles in each of the fan-shaped magnetic poles.
Such a motor is disclosed in US 7,531,934 B2. Said invention relates a method of manufacturing a self-start synchronous motor for preventing deterioration of permanent magnets used in a rotor, and also for

enhancing the efficiency of the self-start synchronous motor, the self-start synchronous motor comprising a stator having a stator core and windings wound around the stator core, and a rotor having an outer diameter slightly smaller than an inner diameter of the stator and arranged inside of the stator. The rotor is provided with a rotor core, a plurality of conductor bars embedded in the outer peripheral portion of the rotor core over an entire periphery thereof, end rings provided on opposite end sides of the conductor bars and constituting a squirrel cage conductor in cooperation with the conductor bars, and a plurality of permanent magnets embedded in the rotor core and arranged at a position inner than that of an inner peripheral surface of the conductor bars. Further, the conductor bars and the end rings are electrically and mechanically joined together through frictional agitation joint. The construction of the rotor described in prior arts wherein magnet buried in rotor stack reduces the outermost diameter of the shaft, thus it reduces shaft strength, moreover the prior arts does not describe to improve the shaft strength.
Objective of the Invention
The object of the invention is to improve strength of the shaft without compromising the outermost diameter of the rotor.
The further object of the invention is to improve strength of the shaft without compromising the motor efficiency.
Yet another object of the invention is to provide a rotor that is simple; cost effective & easy to manufacture.

Summary of the Invention
The present invention relates to a construction of rotor employed in direct line operated permanent magnet synchronous motor, the construction of the rotor improve the strength of the rotor shaft without compromising the outermost diameter of the rotor & motor efficiency.
The present invention comprises of; a rotor shaft incorporated with slots; a magnet placed in said slot of the rotor shaft; a rotor stack having slot to adapt; a conductor bars. Said rotor shaft incorporated with plurality of slots design to retain the magnet in its position.
Brief Description of Drawings
Figure 1 illustrates the Exploded View of the rotor assembly according to the first preferred embodiment of the invention.
Figure 2 depicts the Sectional View of the Rotor Assembly according to the first preferred embodiment of the invention.
Figure 3 illustrates the Exploded View of the rotor assembly according to the second preferred embodiment of the invention.
Figure 4 depicts the Sectional View of the Rotor Assembly according to the second preferred embodiment of the invention.
Figure 5 depicts the Sectional View of the Rotor Assembly according to the third preferred embodiment of the invention.

Detailed Description of the invention
The present invention relates to a construction of rotor employed in direct line operated permanent magnet synchronous motor. The present invention improves the strength of the rotor shaft without compromising the outermost diameter of the rotor & motor efficiency.
According to first preferred embodiment of the invention as described in Figure-1&2. The rotor comprising of: a rotor shaft (01) incorporated with slots (02); a magnet (03); a rotor stack (04) having slots (05) to adapt; a conductor bars (06).
Slots (02) designed to completely adapt the magnet profile, once the said magnet (03) placed in their dedicated slots (02), rotor stack (04) along with short circuited conductor bars (06) press fitted on the shaft (01) in a manner that inner surface of the rotor stack cover the magnet (03) & restrict its movement in radial direction. Wherein closed ends (08) of the slots restrict the axial movement of the magnet (03). Thus the above construction of rotor firmly holds the magnet (03) in its position.
According to second preferred embodiment of the invention as described in Figure-3&4 rotor comprising of: rotor shaft (21) incorporated with slots (22); a magnet (23) securely placed in said slots (22); a rotor stack (24), having slots (25) to adapt; a conductor bars (26); a filler (27) to top up in the slot (22).
Same as described in previous embodiment, rotor stack (24) along with short circuited conductor bars (26) press fitted on the shaft (21) &

prevents the radial movement of the magnet (23), whereas slots (22) have open ends (28), thus to secure the magnet (23) in its position, filler (27) fill up in the air gap between wall of the slots (22) & magnet (23), moreover it covers the opening (28) of the slot to protect the magnet. Said filler material selected from group not limited to Epoxy, Glue.
According to third preferred embodiment of the invention as described in Figure-5, slots (31) to adapt the magnet (34), partially form in shaft (32) & partially form in stack (33).
Technical Advance:
In accordance with the present invention, there is provided a construction of rotor to improve the strength of the rotor shaft, without compromising the outermost diameter of the rotor & motor efficiency. As magnet buried in rotor shaft instead of rotor stack, thus it does not required to reduce inner diameter of the stack, hence it gives more space to increase the outer diameter of rotor shaft, and therefore it improves the shaft strength.
While considerable emphasis has been placed herein on the specific features of the preferred embodiments, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiments without departing from the principles of the invention. These and other changes

in the preferred embodiments of the invention will be apparent to those skilled in the art from the disclosure herein, whereby 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.

CLAIMS
We claim:
1. A rotor for direct line operated permanent magnet synchronous motor, said rotor comprises of: rotor shaft (01) incorporated with slots (02); a magnet (03) securely placed in said slots (02); a rotor stack (04), having slots (05) to adapt; a conductor bars (06).
2. The rotor as claimed in claim 1, wherein said slot (02) have closed end (08) to restrict the axial movement of the magnet (03).
3. A rotor for direct line operated permanent magnet synchronous motor, said rotor comprises of: rotor shaft (21) incorporated with slots (22); a magnet (23) securely placed in said slots (22); a rotor stack (24), having slots (25) to adapt; a conductor bars (26); a filler (27) top up in slot (22) to secure the magnet (23) in its position.
4. The rotor as claimed in claim 3 wherein said filler material selected from a group not limited to epoxy & glue.
5. The rotor as claimed in claim 1 and 3, wherein rotor stack mount on the rotor shaft.

6. The rotor as claimed in claim 1 and 3, wherein said rotor stack restrict the radial movement of the magnet.
7. The rotor as claimed in claim 1 and 3, wherein one of the embodiment of the invention, slots (31) partially formed in rotor shaft (32) & partially formed in stack (33).
8. The rotor as claimed in claim 1 and 3, substantially described with reference to accompanying drawing.