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, 2005
PROVISIONAL SPECIFICATION (See section 10 and rule 13)
TITLE OF INVENTION
Switch Reluctance Motor
INVENTORS
Ekram Samsul and Patwardhan Vinay Satish, Corporate R&D and Quality, Advanced Motor Design and Technology Centre, Kanjur (E), Mumbai 400 042, Maharashtra, India, both Indian Nationals
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 025, Maharashtra, India, an Indian Company
PREAMBLE TO THE DESCRIPTION
The following specification describes the invention.:

FIELD OF INVENTION
This invention relates to a switch reluctance motor.
This invention relates particularly to a switch reluctance motor for use in electrical appliances such as mixer/grinder, washing machine, vacuum cleaner or power tools having a non-conducting material body or housing.
BACKGROUND OF INVENTION
Electrical appliances like mixer/grinder, washing machine, vacuum cleaner or machine tools are generally driven by induction motors or universal motors. Induction motors are not very efficient and suitable for high speed operations. Universal motors are also not very efficient and have reduced life. Switch reluctance motors are ideal for high speed operations and have increased life. They have also other advantages like high efficiency, low cost or rugged construction. Switch reluctance motors are generally used in electrical vehicles as traction motors.
A typical switch reluctance motor comprises a rotor mounted on the rotor shaft and a stator located in a stator housing and disposed around the rotor. The stator casing is fitted with end shields. The rotor comprises poles to provide closed magnetic flux paths around the stator during the operation of the motor. The motor also includes a sensor magnet mounted on the motor shaft externally of one of the end shields. The speed of rotation of the rotor of the motor is sensed through the sensor magnet by hall sensors located either in the corresponding end shield or in the stator slots. The hall sensors are generally located in
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the stator slots with glue or adhesive. In this kind of fitment, there is the possibility of the hall sensors getting dislodged from the stator slots due to vibration or malfunctioning of the hall sensors due to temperature rise in the stator. The hall sensors are generally located in the end shields by screw fit which requires tapped holes to be drilled in the end shield. Screw fitment of the hall sensors in the end shield increases manufacturing time and also cost of manufacture.
DESCRIPTION OF INVENTION
According to the invention there is provided a switch reluctance motor comprising a rotor mounted on a motor shaft and disposed within a stator. The rotor is provided with poles around the circumference thereof. A sensor magnet is mounted on the motor shaft at one end thereof externally of the stator. The sensor magnet comprises poles magnets corresponding to the poles on the rotor. The motor further comprises a sensor mounting end adaptor and a motor mounting end adaptor each removably fitted at each end of the stator. Hall sensors are mounted on a sensor holder which is removably located in the sensor mounting end adaptor. The motor mounting end adaptor is provided with support means whereby the motor can be removably supported on a surface formed or provided in a conducting material body or housing of a mixer/grinder, washing machine, vacuum cleaner, machine tools or the like in which the motor is used.
The following is a description of the invention with reference to the accompanying schematic drawings, in which;
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Fig 1 is an isometric view of a switch reluctance motor according to embodiment of the invention;
Fig 2 is crossectional view of the motor of Fig 1;
Fig 3 is isometric view of the sensor mounting end adaptor of the motor of Fig 1;
Figs 4a and 4b are isometric views of the motor mounting end adaptor of the motor of Fig
l;
Fig 5 is isometric view of the sensor holder of the motor of Fig 1; and
Fig 6 is isometric view of the sensor mounting end adapter with the sensor holder having the hall sensors located therein;
The motor 1 as illustrated in Fig 1 to 6 of the accompanying drawings comprises a rotor 2 mounted on motor shaft 3 and disposed in a stator 4. The poles on the circumference of the rotor are marked 5. 6 is a sensor magnet mounted on the motor shaft at one end thereof externally of the stator. The pole magnets (not shown) of the sensor magnet correspond to the poles of the rotor. 7 is a slotted C-shaped sensor magnet mounting end adapter comprising a base 8 provided with a hole 9 for the motor shaft and a pair of opposite arms 10. The distal ends of the arms are provided with steps marked 11. One face 11a of the step abuts against the corresponding end face of the stator and the other face 1 lb of the step extends over the circumference of the corresponding end of the stator. The arms are
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provided with lugs 12 with mounting holes 13. A pair of spaced apart sensor locators 14 are provided on the base of the end adapter 7. The sensor locators each is provided with a slit 15 at the inner surface thereof. The slits match with each other. The end adaptor 7 is also as provided with support members 16 provided at the base thereof along the same lines as the sensor locators. 17 is planner holder for the hall sensors 18. The planner holder comprises two prongs 19 projecting from it spacedly. The prongs are provided with tapered heads 20. The width of the planner support from one prong to the other prong correspond to the depth between the two slits in the sensor locators. The prongs of the planner holder are slightly flexible or collapsible. The prongs are slightly collapsed or compressed and the prongs are introduced in the slits by their tapered heads which will facilitate sliding engagement of the prongs in the slits. On releasing the holding pressure on the prongs, the prongs will regain their original position and will remain tightly fitted in the slit between the sensor supports. The tapered heads will engage against the sensor locators and retain the prongs engaged in the slits in position. Thus the planner holder with the hall sensors are tightly held in position between the sensor locators with the planar holder also supported against the support members 16. In order to remove the planar from the sensor locators the prongs are slightly collapsed and slid out and disengaged from the slits in the sensor locators. The sensor holder with the hall sensors is aligned with the sensor magnet. 21 is a motor mounting end adaptor comprising a slotted cup shaped member provided with a mounting flange 22. The edge of the end adaptor 22 is provided with strips 23 protruding from it. The edge of the end adaptor 21 abuts against the corresponding face of the stator with the strips overlying the outer circumference of the stator. The flange is provided with mounting holes 24 aligned with lugs and the holes in the lugs in the end adapter 7. The end adapter are removably held onto the stator by screws
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25 tightened in the mounting holes in the flange and the mounting lugs. The flange is also provided with engaging protrusions 26. The motor is removably held or mounted in place in a non-conducting material housing or body (not shown) of a mixer/grinder, washing machine, vacuum cleaner, machine tools or the like in which the motor is used by engaging the protrusions in corresponding holes (not shown) provided in another flange in the housing or body.
The invention eliminates the end shields and stator body of a switch reluctance motor. Instead end adaptors are provided adapted to be removably fitted to the stator. One end adaptor holds the hall sensors, whereas the other end adaptor helps to mount the motor removably on a surface. Fitment of the hall sensors is without glue or adhesive or screws. The hall sensors can be easily fitted and removed and in case of any damage to any one of the hall sensors it can be easily replaced. The motor can also be mounted and removed easily by engaging and disengaging the protrusions in corresponding holes. End shields are generally solid in construction and do not help in dissipation of heat being generated within the motor. The end adaptors are slotted and comprise large openings which will not only save material cost but also facilitate dissipation of heat generated in the motor. The invention also has all the other desirable advantages associated with switch reluctance motors like high efficiency, long life, rugged construction, high speed or low cost.
Dated this 30th day of March 2007.

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