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)
Complete Specification
(See section 10 and rule 13)
TITLE OF THE INVENTION
A press fitting device
APPLICANT
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR
Rohan Nadkarni of Crompton Greaves Limited, Fans & Appliances Division, Plot No 1, Goa IDC Industrial Estate, Bethora, Ponda Goa - 403409, India, an Indian National
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
The present invention relates to a press fitting device. More particularly the invention relates to a press fitting mechanism to detect loose housing in ceiling fan end shield.
BACKGROUND OF THE INVENTION
Ceiling fan housing generally includes a top end shield and a bottom end shield within which a fan motor is disposed between the top end shield and the bottom end shield. The motor includes a stator secured on to a stationary stator shaft that is disposed through a central vent hole provided in the top end shield. An annular rotor is concentrically positioned about the stator and is firmly secured between the top and bottom end shields. During operation, rotor will rotate about stator and its stator shaft. In order to axially secure the stator and the shaft within the top and bottom end shields, the shaft is joumaled in top and bottom end shields between bearings which are centrally positioned within the top and bottom end shields covers, respectively. A top bearing is secured within a bearing bore defined within a bearing hub in the center of the top end shield and similarly a bottom bearing is secured within another bearing hub in the bottom end shield. The top and bottom bearings are press fit into the bearing bore defined within the bearing hubs of the end shields. The bearings are manufactured according to industrial standards and whereas end shields are usually are manufactured using well known casting process and techniques that do not have rigorous dimensional quality checks. Due to dimensional variations caused during the casting process, sometimes, the bearings get loosely press fitted in to the bearing bore within the bearing hub. The ceiling fan housings that are manufactured with such loosely press fitted bearings tend to have a relative motion of the end shields with respect to the bearing and this causes wear out of the end shields over a period of time. Additionally, such a loose end shield also causes a fractional force due to the relative movement present between the end shield and the loose

bearing. The fan motor performs against the frictional force and this therefore leads to increased current requirements. The frictional force also causes heating up of the ceiling fan housing and may cause thermal de-gradation of electrical components and wires that are in close vicinity within the fan housing. Loosely press fitted end shields also cause screeching noise as the fan rotates that is irritating to the ear. It is therefore desirable that during a press fitting operation, the end shields that are not manufactured according to the required dimensions be identified, so that the loosely press fitted end shields can be avoided going further in assembly line.
OBJECTS OF THE INVENTION
An object of the invention is to provide a device for press fitting of a bearing within a bearing hub portion provided in a fan end shield
Another object of the invention is to provide a device to identify a loose press fit engagement between a bearing hub provided in a fan end shield and a bearing.
Another object of the invention is to provide a device to identify a loose press fit engagement between a bearing hub provided in a fan end shield and a bearing that is less expensive and easily operable.
Several aspects of the invention are described below with reference to examples for illustration. It should be understood that numerous specific details, relationships, and methods are set forth to provide a full understanding of the invention. One skilled in the relevant art, however, will readily recognize that the invention can be practiced without one or more of the

specific details,or with other methods, etc. In other instances, well known structures or operations are not shown in detail to avoid obscuring the features of the invention.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention is described a device for press fitting of a bearing within a bearing hub portion defined in a fan end shield. The device comprises of a moveable plate held in spaced apart relationship with a base plate using spring members and a pair of guide rods, the moveable plate having a central opening, the fan end shield being placed on the moveable plate such that the bearing hub portion is positioned concentrically adjacent to the central opening, and a bearing holder firmly secured to the base plate to retain the bearing thereon and allowing for the projection of the bearing through the central opening, and a press fitting mechanism including a hydraulic means that can be activated to control a cylinder and a piston rod such that the piston rod exerts upon the fan end shield a first pre-defined pressure in a first downward stroke of operation and a press fitting pressure in a second downward stroke of operation, and wherein the first pre-defined pressure is lesser than the press fitting pressure and wherein the fan end shield when exerted upon by the press fitting pressure causes the bearing hub and the bearing to get press-fitted against each other, and a limit switch electrically coupled to the hydraulic means and identifies a downward traversal of the moveable plate to a pre-determined position in the first downward stroke of operation and deactivates the hydraulic means and wherein the downward traversal of the moveable plate to the pre-determined position indicates a loose press fit engagement between the bearing hub and the bearing.

The following is a detailed description of the invention with reference to the accompanying drawings, in which:
Fig 1 illustrates the alignment of a fan end shield and a bearing.
Fig 2a and Figure 2b illustrates a device used for press fitting of the fan end shield and the bearing according to the present invention.
Fig 3 illustrates a moveable plate of the device according to the present invention on which the fan end shield can be placed.
Fig 4 illustrates a hydraulic circuit according to the present invention what be used in a press fitting mechanism.
Figure 1, illustrates a fan end shield 1 and a bearing 2. Fan end shields are usually made up of aluminum have a bearing hub 3 defined in the center. The bearing hub 3 has slightly lesser diameter than the bearing 2. In a press fitting operation of the fan end shield against the bearing, the fan end shield is carefully placed so that the bearing hub is axially aligned with the bearing which is firmly positioned on a bearing holder. A force is then applied to the fan end shield 3 against bearing 2 and as a result, the bearing hub 3 gets thermally expanded to firmly accommodate bearing 2. The press fitting operation using the device as claimed in the invention can be better understood in relation with Figures 2a-2b and Figure 3.
Figure 2a-2b illustrates the device used for press fitting of the fan end shield and the bearing. The device is shown comprising of a moveable plate 7 being held in spaced apart relationship

with a base plate 11 using guide rods 9 and spring members 8 and bolts 13. The guide rods 9 are firmly secured with the base plate 11 and are uprightly disposed within spring members 12. Bolts 13 are firmly secured with the base plate Hand define the distance between the moveable plate 7 and base plate 11. A bearing holder 10 is firmly disposed uprightly on the base plate 11. As illustrated in Figure 3, the moveable plate 7 has a central opening 4, which is circular in shape. The bearing holder 10 is positioned below the moveable plate 7 and is located under the central opening 4. In Figure 3, the bearing 2 is shown placed over the bearing holder 10. A circular disc 14 with a central opening 4 is firmly mounted over a circular plate 15 having a rimmed surface and another central opening. The arrangement of the circular disc 14 and the circular plate 15 is firmly mounted on the moveable plate 7. The fan end shield 1 as shown in Figure 1 is overturned and placed on the circular disc 14 in a manner such that the circumferential surface of the fan end shield 1 coincides with the rimmed surface of circular plate 15. Such an arrangement of the fan end shield 1 with the rimmed surface leads to a correct alignment of the bearing hub 3 with the central opening 4. When the circumferential surface of fan end shield 1 does not coincide with the rimmed surface the bearing hub 3 is not placed concentric to the bearing 2 and this may not lead to the desired press fit between them. As may be noticed further in Figure 3, the bearing 2 when placed on the bearing holder 10 is almost at the same surface level as that of the circular disc 14.
In Figure 2b. the piston 6 is shown in exerting pressure on the fan end shield 1. Piston 6 is driven by a hydraulic means and provides a first pressure in a first stroke of operation. In the first stroke of operation, the pressure delivered to the fan end shield l is lower than the pressure that is actually required for a proper press fit. In the event that a fan end shield 1 has incorrect dimensions, i.e. has a bearing hub 3 that has a greater diameter than required, the

bearing 2 slips in easily within the hub 3 and the fan end shield 1 gets displaced towards the circular disc 15 and pushes the moveable plate 7 downwards. The downward movement of the moveable plate 7 triggers a limit switch 4 that is placed below the plate 7 at a predetermined position. The limit switch 4 provides an indication of the downward movement of the plate 7 by completing an electric circuit and glowing of an indicator bulb 5 that indicates a presence of a fan end shield with incorrect dimensions. In such an event the limit switch 4 further disables the hydraulic means for providing a successive stroke of piston operation. The press fitting device comes to a halt and an operator in charge can remove the fan end shield 1 from the device.
When a fan end shield is made of correct dimensions, i.e. has a bearing hub that has slightly smaller diameter than the bearing, the bearing does not get easily accommodated within the hub and requires a substantial amount of pressure to be exerted to get press fitted . In press fitting operation of fan end shield with correct dimensions, during the first stroke of operation the piston 6 operates to provide a first pressure on the fan end shield 1, the bearing 2 bears and opposes the force as exerted on the fan end shield 1. The fan end shield 1 remains positioned as is and does not traverse downwards to displace the moveable plate 7. In such a case, the limit switch 4 is not triggered. The hydraulic means is controlled to operate the piston rod 6 to provide for a second stroke at a press fitting pressure in the event that a loose press fit is not detected at the end of the first stroke of piston. Thus during the second stroke of operation the piston rod 6 delivers a press fitting pressure to the fan end shield 1. The bearing hub 3 within the fan end shield 1 thermally expands to accommodate the bearing 2.
The manner in which the hydraulic means operates to provide a first pressure during the first stroke of operation and a press fitting pressure during the second stroke of operation is

illustrated in Figure 4 by means of the hydraulic circuit that drives a double action cylinder that drives the piston rod.
Figure 4 is a hydraulic circuit used in the press fitting mechanism used in the device according to the present invention. The hydraulic circuit controls the movement of hydraulic fluid in to a double acting cylinder 40 to control and provide for a first pressure of piston rod movement during the First pressure in the first (downward) stroke of piston operation and the press fitting pressure during the successive (downward) stroke of piston operation. The pressure at which the hydraulic fluid enters into the double acting cylinder 40 decides the pressure at which the piston rod moves downward.
A hydraulic pump 43 can be tuned 'ON' or 'OFF' by a master switch (not shown) to activate or de-activate the hydraulic pump. The hydraulic pump 43 pumps hydraulic fluid along a fluid line represented as 'A' in Fig 4. The fluid pressure in fluid line 'A' is maintained at a known press fitting pressure by means of pressure gauge 45 and relief valve 44. The relief valve 44 can be tightened or released to maintain a scale reading corresponding to the press fitting pressure on the pressure gauge 45.
A bi-directional control valve 41 receives the hydraulic fluid along fluid line 'A' at its input and is capable of controlling the hydraulic fluid movement along two fluid lines 'B' and 'C at the output. Fluid line 'B' is connected to a bi-furcated fluid line pipe (not shown) with a first output and a second output. The first output is connected to a dc solenoid valve 42 at its input. The output of the dc solenoid valve 42 is connected to a relief valve 46. The second output of the bi-furcated fluid line pipe (not shown) forms a fluid line D. The dc solenoid valve 42 remains open for a finite duration of time to release a portion of the hydraulic fluid

coming from the bi-directional control valve 41 flow through relief valve 46. This diversion of fluid causes some portion of the hydraulic fluid to proceed through fluid line 'D' The dc solenoid valve 42 remains open for the finite duration of time so as to cause the hydraulic fluid though fluid line 'D' at a reduced pressure (first pre-defined pressure). Fluid line 'D' is connected to the double acting cylinder 40. The piston on receiving the hydraulic fluid at reduced pressure moves downward to complete the first downward stroke of operation. The first stroke of piston operation at the reduced pressure checks for loose press fitting engagement of the fan end shield land the bearing 2. During the downward movement of the piston the hydraulic fluid flows though a fluid line 'C and is received by the bi-directional control valve 41. As the piston moves downward during the first stroke of operation a pressure switch 48 senses the pressure as exerted by the double acting cylinder 40. The pressure switch 48 is internally set to operate at a pre-set pressure (second pre-defined pressure). As and when the pressure switch 48 senses the pre-set pressure being exerted in fluid line 'C' it de-activates the dc solenoid valve. The piston rod is bought back to the top in the double acting cylinder 40 and then the bi-directional valve allows for the hydraulic fluid at press fitting pressure to directly flow to the double acting cylinder 40 and in such a manner the piston comes downward for a second stroke of operation at a press fitting pressure. In the event that a loose press fitting engagement is found during the first stroke of operation, the limit switch 4 de-activates the hydraulic circuit by turning 'OFF' the power connection to the hydraulic pump 43.

We Claim:
1. A device for press fitting of a bearing within a bearing hub defined in a fan end shield, the device comprising:
a moveable plate held in spaced apart relationship with a base plate using spring members and a pair of guide rods, the moveable plate having a central opening, the fan end shield being placed on the moveable plate such that the bearing hub is positioned concentrically adjacent to the central opening, and
a bearing holder firmly secured to the base plate to retain the bearing thereon and allowing for the projection of the bearing through the central opening, and
a press fitting mechanism including a hydraulic means that can be activated to control a cylinder and a piston rod such that the piston rod exerts upon the fan end shield a first pre-defined pressure in a first downward stroke of operation and a press fitting pressure in a second downward stroke of operation, and
wherein the first pre-defined pressure is lesser than the press fitting pressure and wherein the fan end shield when exerted upon by the press fitting pressure causes the bearing hub and the bearing to get press-fitted against each other, and
a limit switch electrically coupled to the hydraulic means and identifies a downward traversal of the moveable plate to a pre-determined position in the first downward stroke of operation and de-activates the hydraulic means and

wherein the downward traversal of the moveable plate to the pre-determined position indicates a loose press fit engagement between the bearing hub and the bearing.
2. The device of claim 1, wherein the hydraulic means comprising of: a hydraulic pump, a first pressure gauge and a first relief valve in fluid connection with each other; the first pressure gauge and the first relief valve to be operated to provide for hydrauli fluid at the press fitting pressure to a double acting direction control valve, the double acting direction control valve in series connection with the input of a bifurcated fluid output, and
a dc solenoid valve connected to a first output of the bifurcated fluid output, the dc solenoid valve selectively activated to allow the hydraulic fluid at the second output of the bifurcated fluid output at the first pre-defined pressure for the first downward stroke of operation of the piston rod and the press fitting pressure for the second downward stroke of operation of the piston rod, and
wherein the dc solenoid valve when activated allows a portion of hydraulic fluid to get released through a second relief valve thereby allowing the hydraulic fluid at the second output to exert the first pre-defined pressure, and
a pressure switch connected to the cylinder and the double acting direction control valve to sense a second pre-determined pressure during the first downward stroke of operation and control the double acting direction control valve to allow the hydraulic fluid with the press fitting pressure in the cylinder for a upward stroke of the piston rod.

3. The device of claim 1. wherein the limit switch is positioned below the moveable plate at
the pre-determined position and is activated when the moveable plate pushes down the limit
switch, and
wherein the limit switch when activated energizes a bulb to indicate the loose press fit engagement.
4. The device of claim 1 being switched 'ON' or switched 'OFF' by a master switch,
wherein the master switch when 'ON' powers up the press fitting mechanism and when
'OFF' powers down the press fitting mechanism.