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, 2006
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
A testing device for testing performance of a rotor under dynamic conditions
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR
Kamble Deepak Gajanan of Crompton Greaves Limited, Engineering Department, Global R&D Centre, Kanjur Marg (E), Mumbai 400042, Maharashtra, India, an Indian National.
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed:

FIELD OF THE INVENTION
The present invention relates to testing devices for testing actual performance of
rotors of external rotor motors.
DESCRIPTION OF THE BACKGROUND ART
Testing of rotors is a mandatory pre-requisite to rotors prior to their installation with motors. The testing of rotors or magnetic rotors is primarily done so as to determine whether parameters of rotors are inline with the standard parameters (for on-load conditions) or, if any unacceptable deviations have occurred. Deviation from the standard parameters is quite imminent in rotors that are manufactured at one location and transported to a distant location as the standard parameters set during manufacturing may change due to mishandling during transportation.
Even a slight deviation form the standard parameters could result in the actual performance of the rotors being greatly hampered. The parameters on which the actual performance of the rotor during on-load condition is decided generally include magnetic flux, volts, current, watt, and RPM. There are few conventional testing devices available currently, however, those do not determine all of these parameters during on-load conditions before the rotors are assembled with the motor.
For example, one of the conventional systems uses that check rotors uses a probe to check only the flux density of the rotors. If motors that are checked only for their magnetic flux density assembled in a motor they may get rejected in performance test. This will lead to huge losses in cost and rejection in productivity. Another major problem with the conventional devices is that they cannot determine whether the

rotors have developed hair crack during their transportation until they are assembled with the motors. This is due to the fact that if any of the rotors have developed hair crack, an additional pole will be generated therein and this will lead to a stator unable to sense the number of magnetic poles in the rotor. Eventually, the rotor will stop rotating and this will lead to wastage of time, money and labor. However, such cracks cannot be detected with the present available devices.
Thus there is a need for a testing device that tests the rotors during on-Ioad conditions to determine actual performance of the rotors.
SUMMARY OF THE INVENTION
Disclosed herein is a testing device for testing performance of a rotor under dynamic conditions, the device comprises a base, a pair of upstanding fixed plates mounted to the base and positioned in spaced apart relationship with each other, a rotor housing mounted to one of the fixed plates for rotation about a horizontal axis and having its inner surface adapted to removably hold the rotor, a locking means for locking the rotor in the rotor housing, an upstanding slidable plate for mounting a stator and an electronic controller connected to the stator, the slidable plate adapted to describe guided forward and backward linear movement between the fixed plates, and a guiding device mounted to other of the fixed plates and connected to the slidable plate to linearly move the slidable plate and the stator forward and backward.
In some embodiments, the guiding device includes a pair of guide rods mounted between the pair of fixed plates, the guide rods allowing the slidable plate to move backward and forward thereon.

In some embodiments, the testing device includes a cylinder connected to an outer surface of one of the fixed plates, the cylinder having a reciprocating shaft passing through the fixed plate to operably engage the slidable plate for providing guided forward and backward linear movement to the slidable plate.
In another embodiment, the locking means comprises of a locking nut having a having ia plurality of cut portions formed therein, each of the plurality of cut portions removably engaging a corresponding groove formed within the inner surface of the rotor housing.
Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the invention as described herein, including the detailed description which follows, the claims, as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description of the present embodiments of the invention and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the invention and together with the description serve to explain the principles and operation of the invention.

A BRIEF DESCRIPTION OF THE DRAWINGS
The above-mentioned and other features and advantages of the various embodiments of the invention, and the manner of attaining them, will become more apparent will be better understood by reference to the accompanying drawings, wherein: FIG. 1 is a perspective view of a testing device showing a stator and a rotor in an open configuration according to an embodiment of the present invention;
FIG. 2 is an exploded view of the testing device of FIG. 1;
FIG. 3 shows a perspective view of the testing device of FIG. 1 showing the stator and the rotor in closed configuration; and
FIG. 4 is a cross-sectional front side view of the testing device of FIG. 3 showing connection between a cylinder and its shaft with one a fixed plate and a slidable plate according to one embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a perspective view of a testing device 100 according to an embodiment of the present invention. The testing device 100 includes a base 102 and a pair of fixed plates, hereinafter referred to as a first fixed plate 104 and a second fixed plate 106, fixedly mounted to the base 102. The base 102 has a length (L), a width (W), and a thickness (T) defining the base 102. Both the first fixed plate 104 and the second fixed plate 106 are mounted in upstanding orientation to the base 102. Preferably, both the first fixed plate 104 and the second fixed plate 106 are mounted adjacent to a

first end 108 and a second end 110, respectively, of the base 102. The first end 108 and the second end 110 define the length (L) of the base 102.
The first fixed plate 104 has a rotor housing 112 mounted to an inner surface 114 of the first fixed plate 104 and is rotatably engaged therewith. The rotor housing 112 is defined by a generally hollow cylindrical body 116 having an inner surface 118 and an outer surface 120 and rotatable about its horizontal axis with respect to the first fixed plate 104. Preferably, as shown in FIG. 2 that shows an exploded view of the testing device 100, the rotor housing 112 is rotatably engaged with the first fixed plate 104 by a rotor shaft 122 and a pair of bearings 124 having a spacer 126 positioned therebetween. The rotor shaft 122 is coupled to the first fixed plate 104 by a fastening member 128 for example, a screw or by a nut bolt arrangement. The pair of bearings 124 and the spacer 126 allows the rotor housing 112 to be rotatably coupled to the rotor shaft 122. Assembled view of the rotor housing 112 with the first fixed plate 104 is shows in FIG. 4.
As shown in FIG. 1, the rotor housing 112 also holds a rotor 130 that is rotatably mounted to the inner surface 118 of the rotor housing 112. Preferably, the rotor 130 is a magnetic ring having a plurality of equal opposite (North-South) poles therein. As an outer diameter of the rotor 130 is smaller than inner diameter of the rotor housing 112, the rotor 130 is easily fitted to the rotor housing 112 and mounted to the inner surface 118 thereof. In another embodiment of the present invention, a locking nut 132 that removably engages the inner surface 118 of the rotor housing 112 to lock the rotor 130 against the rotor housing 112. Preferably, the inner surface 118 of the rotor housing 112 has a groove 134 formed on the inner surface 118 of the rotor housing

112. Further, the lock nut also has a plurality of cut portions formed on an outer surface of the locking nut 132. Preferably, the groove 134 is circular in shape extending along the inner surface 118 of the rotor housing 112 to accommodate shape of the rotor housing 112, which is generally circular in shape.
Each of the cut portions 136 of the locking nut 132 detachably engages a corresponding groove 134 so as to lock the locking against the rotor housing 112. As the rotor 130 is positioned behind the locking nut 132 within the rotor housing 112, due to this locking of the locking nut 132, the rotor 130 is securely positioned within the rotor housing 112. On removal of the locking nut 132, the rotor 130 is easily removed from the rotor housing 112. In other embodiments of the present invention, other means and mechanisms to lock the rotor 130 against the rotor housing 112 are also envisaged within the scope of the present invention.
As shown in FIG. 1, a slidable plate 138 is slidably disposed between the first fixed plate 104 and the second fixed plate 106. The slidable plate 138 is disposed in upstanding orientation between the first fixed plate 104 and the second fixed plate 106 and is movable therebetween. Further, a guiding device is also mounted in between the first fixed plate 104 and the second fixed plate 106 so as to slidably mount the slidable plate 138 thereon. Preferably, the guiding device includes a pair of guide rods 140 fixedly mounted adjacent to the two upstanding edges, respectively, of the first fixed plate 104 and the second fixed plate 106. As seen from FIGS. 2 and 3, each of the guide rods 140 have a sliding bush 142 slidably adapted thereon. Mounting position of the pair of guide rods 140 is such that the rotor housing 112 is substantially positioned in between the pair of guide rods 140.

Further, as shown in FIGS. 1-3, the slidable plate 138 has a pair of holes 144 formed therein to receive a corresponding guide rod 140 therein. Each of the pair of guide rods 140 is received within a corresponding pair of holes 144 in such a manner that each of the each of the sliding bushes 142 of the pair of guiding rods is fixedly attached to each of the pair of holes 144. This allows the slidable plate 138 to move over the guide rods 140 thereby allowing the slidable plate 138 to move between the first fixed plate 104 and the second fixed plate 106. Furthermore, the pair of holes 144 is provided adjacent to a bottom edge 146 of the slidable plate 138 so that when the slidable plate 138 is received within the pair of guide rods 140 a small gap (G) is maintained between the base 102 and a bottom edge 146 of the slidable plate 138. This gap (G) ensures that the slidable plate 138 is freely movable on the pair of guide rods 140 (See FIG. 4).
The slidable plate 138 has a stator 148 fixedly mounted thereto. Preferably, the stator 148 is a wound stator that is coupled to the second fixed plate 106 by a stator shaft 150 and a bush 152 (FIGS. 1 and 2). An outer diameter of the stator 148 is smaller than an inner diameter of the rotor 130 so that the stator 148 is received within the rotor housing 112. Preferably, the testing device 100 is used to test the rotor 130 of a brushless direct current (BLDC) external rotor motor under dynamic conditions. As seen in FIG. 1, an electronic controller, which is preferably a PCB, is also mounted to the slidable plate 138 and positioned on a back side 156 of the stator 148. The electronic controller 154is electrically connected with the stator 148 to provide necessary electrical power to the stator 148. The electronic controller 154derives power from an external power source (not shown).

Referring to FIGS. 1-4, an outer surface 158 of the second fixed plate 106 has a cylinder 160 that has a reciprocating shaft 162 therein. As seen in FIG. 2, the second fixed plate 106 has a hole 164 that receives the reciprocating shaft 162. Further, the reciprocating shaft 162 passes completely through the second fixed plate 106 and is connected to a back surface 166 of the slidable plate 138. Preferably, the reciprocating shaft 162 is connected to an adapter 168 that is connected to the back surface 166 of the slidable plate 138. Further, it is also known by virtue of the cylinder operation that the reciprocating shaft 162 is subjected to a forward and a backward stroke. This forward and backward stroke gets transferred in the form of linear motion to the slidable plate 138.
Thus, as the slidable plate 138 is freely movable on the pair of guide rods 140, the slidable plate 138 linearly moves forward and backward in correspondence with the forward and backward strokes exerted on the reciprocating shaft 162. This allows the reciprocating shaft 162 to describe a guided forward and backward linear motion between the first fixed plate 104 and the second fixed plate 106. Preferably, the cylinder 160 used to perform the guided motion of the slidable plate 138 is a pneumatic cylinder. However, in other embodiments of the present invention, hydraulic cylinders may also be used and be considered within the scope of the present invention.
As shown in FIGS. 3 and 4, when the cylinder 160 exerts a forward stroke on the reciprocating shaft 162, the slidable plate 138 linearly moves forward towards the first fixed plate 104. Due to this linear movement, the stator 148 approaches the rotor

housing 112 thereby allowing the stator 148 to be oriented with the rotor 130 in closed configuration. When the cylinder 160 exerts a full stroke on the reciprocating shaft 162, the slidable plate 138 is further moved linearly towards the rotor housing 112 thereby positioning the stator 148 within the rotor housing 112. The closed configuration of the stator 148 and the rotor 130 is shown in FIGS. 3-4. On the contrary, when the cylinder 160 exerts a backward stroke, the slidable plate 138 linearly moves backward from the first fixed plate 104 allowing the stator 148 to be linearly moved away from the rotor 130. This allows the stator 148 to be positioned in open configuration with respect to the rotor 130 (See FIG. 1).
Once the stator 148 and the rotor 130 are in closed configuration with respect to each other, the rotor 130 is rotated within the housing. Principle of rotation of the rotor 130 within the stator 148 of any BLDC external rotor 130 motor is well known in the art. For example, a sensor (not shown) that is coupled to the electronic circuit senses the immediate polarity of the rotor 130 positioned in front of the stator 148 and sends the signal representative of the polarity to the electronic controller. The electronic controller 154creates a similar polarity on the rotor 130 facing the stator 148.
Due to creation of similar poles at the stator 148, a repulsive force between the stator 148 and the rotor 130 is generated that results in a torque created therebetween. Since the stator 148 is fixedly attached to the inner surface 118 of the rotor housing 112, in order to compensate for the torque, the rotor 130 as well as the rotor housing 112 starts rotating. Further, as the rotor 130 starts rotating, the magnetic polarity facing the sensor varies. Accordingly, the sensor sends signals to the electronic controller 154which in turn change the polarity of the stator 148 to become similar to that of the

rotor 130. This leads to generation of a continuous torque, which helps in moving the rotor 130 and the rotor housing 112 against the stator 148.
Once the rotor 130 starts rotating (subjected to dynamic conditions) tests relating to actual performance of the rotor 130 are conducted. Actual performance of the rotor 130 is generally ascertained by obtaining voltage (V), current (A), watt (W), and rotation per minute (RPM) values of the stator 148 during dynamic conditions and then comparing these values with a standard set of predetermined values. In order to obtain the current values under dynamic condition, a V.A.W. meter (not shown) is electrically connected to the stator 148 that gives readings pertaining to the current, volt, and wattage. Additionally, for obtaining RPM values of the rotor 130, a speed sensor sticker (not shown) is preferably stuck to the rotor housing 112. By engaging a tachometer (not shown) with the speed sensor sticker appropriate RPM readings of the rotor 130 under dynamic conditions is determined.
Thereafter, actual performance of the rotor 130 is determined by comparing the obtained values with the standard set of values and calculating the extent of deviation between the two values set. So, by determining the actual performance of the rotor 130, appropriate decision relating to rejecting the rotor 130 is easily taken. For example, if the rotor 130 does not rotate then during test, then the possibility of the rotor 130 developing hair crack is very high and as a result of this such rotors 130 are immediately rejected. Thus, such rotors 130 being accidently assembled with the motors is avoided resulting in substantial saving of time, cost, and labor. Another benefit of the various embodiments of the present invention is that the testing machine gives all the performance data without assembling the rotor 130 with the actual motor.

It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention. Thus it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

We Claim:
1. A testing device for testing performance of a rotor under dynamic conditions, the
device comprising:
a base;
a pair of upstanding fixed plates mounted to the base and positioned in spaced apart relationship with each other;
a rotor housing mounted to one of the fixed plates for rotation about a horizontal axis and having its inner surface adapted to removably hold the rotor;
a locking means for locking the rotor in the rotor housing;
an upstanding slidable plate for mounting a stator and an electronic controller connected to the stator, the slidable plate adapted to describe guided forward and backward linear movement between the fixed plates; and
a guiding device mounted to other of the fixed plates and connected to the slidable plate to linearly move the slidable plate and the stator forward and backward.
2. The testing device according to claim 1, wherein the guiding device includes a pair of guide rods mounted between the pair of fixed plates, the guide rods allowing the slidable plate to move backward and forward thereon.
3. The testing device according to claim 1, further comprising a cylinder connected to an outeT surface of one of the fixed plates, the cylinder having a reciprocating shaft passing through the fixed plate to operably engage the slidable plate for providing guided forward and backward linear movement to the slidable plate.

4. The testing device according to claim 3, wherein the slidable plate linearly moves forward towards one of the fixed plates for positioning the stator within the rotor housing when the reciprocating shaft exerts a forward stroke.
5. The testing device according to claim 4, wherein the stator is disposed within the rotor housing when the reciprocating shaft exerts a forward stroke on the slidable plate to allow the slidable shaft to linearly move forward towards the fixed plate having the rotor housing mounted thereto.
6. The testing device according to claim 5, wherein the stator is disposed in spaced apart relationship with the rotor housing when the reciprocating shaft exerts a backward stroke on the slidable.
7. The testing device according to claim 1, wherein the locking means comprises of a locking nut having a having a plurality of cut portions formed therein, each of the plurality of cut portions removably engaging a corresponding groove formed within the inner surface of the rotor housing.
8. The testing device according to claim 1, wherein the rotor housing is rotatably mounted to a rotor housing shaft that rotatably engages one of the fixed plates.