Title of Invention

A MOUNTING ARRANGEMENT FOR AN EXTERNAL OVER LOAD PROTECTOR DEVICE FOR A HERMETIC COMPRESSOR

Abstract

A mounting arrangement for an external over load protector device for a hermetic compressor housed in body consisting of an upper and a lower shell and a hermetic terminal extending from the lower shell; said mounting arrangement comprising a. a rigid bracket [22] with a formed slot [26], said rigid bracket [22] adapted to be mounted on the flat surface [13,50] of the lower shell [12] of the body of the compressor, below the said hermetic terminal [14] and; b. a compressible holder [14] adapted to encompass an overload protector in its operative configuration, the said holder having resilient prongs [28] extending therefrom said prongs adapted to be resiliency deformed and snap fit in the formed slot of the rigid bracket.

Full Text

FORM-2 THE PATENTS ACT, 1970 (39 of 1970) & THE PATENTS RULES, 2003 COMPLETE Specification (See section 10 and rule 13) A MOUNTING ARRANGEMENT FOR AN EXTERNAL OVER LOAD PROTECTOR DEVICE FOR A HERMETIC COMPRESSOR EMERSON CLIMATE TECHNOLOGIES (INDIA) LIMITED an Indian Company of 1202/1, Ghole Road, Pune 411 004, Maharashtra, India GRANTED THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED. -2 FEB 2007 2-2-2007 Field of invention: This invention relates to hermetic compressors. In particular this invention relates to a novel mounting arrangement for over load protector device for hermetic compressors. Description of prior art: Hermetic sealed compressors are used to compress low-pressure vapor from an evaporator and deliver high pressure and high temperature vapour to a condenser. In a typical hermetic compressor of the reciprocatory type, suction gas enters the shell cavity through a suction tube. This gas is sucked in the suction muffler due to suction stroke of the piston. The gas flows to a cylinder bore via a suction plenum in the cylinder head through a passage in the crankcase or connecting tubes between the suction muffler and suction port in a valve plate. This low-pressure gas is compressed to high pressure and delivered to the discharge muffler via a discharge port in the valve plate to the cylinder head plenum. In the discharge plenum gas is attenuated and delivered to the condenser of the appliance through a discharge tube of the compressor. Typically, the hermetic compressor generally comprises a lower and upper shell, inside which three or more flexible members hold the pump assembly. The whole assembly body is supported by legs, which are attached to a shell. The pump assembly consists of a motor component stator and rotor and gas compressor mechanism. The rotor is fitted directly on the crankshaft. The crankshaft is housed in the main bearing provided in the crankcase. The stator is mounted on the crankcase through fasteners. The power required for a motor which gives rotation of the crankshaft is supplied via a hermetic terminal mounted on the lower shell. The lower shell is in the form of a cylindrical elongate cup having principally a curved outer surface with a planar part on which the hermetic terminal is mounted. The protector bracket is provided near hermetic terminal to protect hermetic terminal from shocks or impact of foreign bodies . The protector bracket also plays the role of providing support for overload protector holding spring, and arrangement for terminal cover. An over load protector is generally provided in a hermetic compressor. The overload protector detects any unusual heat and fluctuations in the current or amperage taken by compressor during operation. This unusual heat or change in the current or amperage of the compressor causes a bimetallic strip within the protector device to shut off power supply to the compressor. Internal overload protectors are known but these protectors are very sensitive and subject to nuisance tripping in typical applications of the compressor and are also very expensive. Therefore the concept of external overload protector devices was conceived. This invention relates to external over load protectors for hermetically sealed compressors, and particularly for a novel mounting arrangement for such protectors. In the prior art, the overload protectors are mounted on the curved surface of the shell by a an elaborate bracket as seen in figures 1 to 7 of the accompanying drawings. The contact surface between the protector and the surface of the shell is an arc to plane contact and thus the contact for sensing is small. There is a need for quicker sensing. However, it has not been hitherto possible for the overload protector to be mounted on the flat surface of the shell because of limitation of available space. An object of this invention is to provide a mounting arrangement for external overload protectors for hermetically sealed compressors, which mounting arrangement will permit the overload protector to be mounted on the flat surface of the shell. Summary of the invention: According to this invention there is provided a mounting arrangement for an external over load protector device for a hermetic compressor housed in body consisting of an upper and a lower shell and a hermetic terminal extending from the shell; said mounting arrangement comprising i. a rigid bracket with a formed slot, defined by a front wall and side walls , said bracket adapted to be mounted on the flat surface of the lower shell of the body of the compressor, below the said hermetic terminal and; ii. a compressible holder adapted to encompass an overload protector in its operative configuration , the said holder having resilient prongs extending therefrom said prongs adapted to be resiliently deformed and snap fit in the formed slot of the rigid bracket. Typically, the bracket is defined by a back wall and a recess is cut in the said back wall and the slot is formed in the said recess. Typically, the said bracket is made of steel and the said slot is formed in the said back wall of said bracket by pressing. Typically, the side walls of the recess are tapered towards the slot. Typically, the holder is ring shaped. Typically, the free ends of the prongs are provided with teeth formations, said teeth formations having notches which latch on the said side walls of the slot in the operative configuration of the mounting arrangement. In accordance with a preferred embodiment of the invention the outer body of the overload protector is provided with a groove to securely accommodate the holder. Typically, the said bracket is provided with side walls extending from the bracket which protect the overload protector mounted in the operative configuration of the arrangement. Brief description of the invention: Other aspects and advantages of the present invention may become apparent upon reading the following detailed description and upon reference to the accompanying drawings in which: Figure 1 illustrates the partial top view of compressor and overload protector mounting arrangement in prior art; Figure 2 illustrates the perspective view of lower shell assembly; Figure 3 illustrates the perspective view of protector bracket; Figure 4 illustrates the overload holder spring; Figure 5 illustrates overload protector assembly; Figure 6 illustrates partial front view of overload protector and protector bracket assembly; Figure 7 illustrates perspective view of overload protector assembly; Figure 8 illustrates partial top view of the compressor and overload protector mounting arrangement present invention; Figure 9 illustrates perspective view of lower shell assembly; Figure 10 illustrates perspective view of protector bracket and overload protector holding bracket; Figure 11 illustrates front view of overload protector holder; Figure 12 illustrates overload protector assembly; Figure 13 illustrates partial front view of protector bracket and overload protector holder; Figure 14 illustrates the perspective view of overload protector holding arrangement; and Figure 15 illustrates temperature vs time plot for comparison of response time of overload protector. The invention will be described with reference to the accompanying drawings, in which the following numbers represent the corresponding components marked in the figures in the accompanying drawings: 12 Shell of the Compressor 14 Hermetic Terminal 16 Overload Protector 18 Overload Holder or Spring 20 Protector Bracket 22 Protector Bracket Overload-cum-Mounting Bracket 24 Overload Protector Holder. 26 slot Portion in (22) 28 Compressible Prong/Elements of (22) 30 Back Surface of Overload Protector 32 Pins of Hermetic Terminal. 34 Leg Bracket of Compressor. 36 Suction Tube of Compressor. 38 Terminal On Overload Protector 40 Lead Wire for Clip (42) Connection to (44) 42 Clip for Connection 44 Terminal provided on the Overload Protector for Connecting (40) 46 Terminal provided on the Overload Protector. 48 Curved Surface of the Lower Shell. 50 Flat surface on the Lower Shell. 52 Screw provided on the Overload Protector. 54 Discharge Connector Tube of Compressor. 56 Internal Mounting Bracket of the Compressor Assembly. Detailed description of the present invention: The external overload protector device as in the prior art is a bimetallic strip switch provided in a housing which is fitted externally to the lower shell of a hermetic compressor as seen in figures 1, 2,3,4,5,6 and 7 of the accompanying drawings. In figures 1 to 7, the lower shell of the compressor is designated by the reference numeral 12, the hermetic terminal by 14, the over load protector by 16 and the spring and the mounting bracket of the arrangement in the prior art for the over load protector is designated by the numerals 18 and 20. As shown in figure 1 the back surface of overload protector (30) acts as enclosure to transmit the heat from surrounding to the bimetal disc. The pines of the hermetic terminal (32) conduct electrical supply to the internal motor. The leg bracket of the compressor (34) as shown in figure 2 supports the overall compressor body. The suction tube of compressor (36) takes the gas evaporator outlet to the compressor. The lead wire (40) for clip (42) connection to terminal (44) provided on the overload protector carries the electrical supply to the hermetic terminal component. One extra terminal (46) is also provided to carry electric supply. The curved surface of the lower shell (48) is the outer surface of compressor shell which transmits the internal heat and suppresses the sound. The flat portion on the lower shell (50) is provided for the welding purpose of the hermetic terminal. A screw (52) on the overload protector for adjustment of the bimetal strip in response to the disc opening and closing times. The discharge connector tube (54) of compressor carries high-pressure refrigerant form compressor to condenser. The internal mounting bracket (56) of the compressor assembly support the internal pump assembly component. The overload protector of the prior art as seen in figure 1 contacts the cylindrical surface of the shell 12. The bottom surface of the over load protector is typically a disc made of metal or plastic or some times kept completely open. The contact between the flat surface of the protector and the curved surface of the shell is at best imperfect and this causes a delay on the transference of heat from the shell to the body of the protector, resulting in the running of the compressor at the unintended conditions. The novel arrangement is seen in figure 8 of the accompanying drawings. The overload protector is mounted on the flat surface [13,50] of the lower shell 12. In accordance with this invention, as shown in figures 8 to 14, the mounting arrangement for the over load protector in accordance with this invention is a mounting bracket 22 and a holder 24. The bracket is adapted to be fitted near or around the hermetic terminal 14 and hence on the flat portion of the lower shell 12. The bracket 22 has a formed slot 26 and the holder 24 has a compressible prong 28. The prongs are compressed and fitted in the slot of the bracket as seen in figure 8. The mounting arrangement for the external over load protector device consists of a rigid bracket 22 with a formed slot 26 and a holder 25. The bracket 22 is adapted to be mounted on the flat surface 13 of the lower shell 12 of the body of the compressor, below the said hermetic terminal 14. The bracket 22, as particularly seen in figure 10, is defined by a back wall 23 a, and side arms 23b. A recess 23c is cut in the said back wall 23a and the slot 26 is formed in the said recess. As seen in figure 10, the side walls defining \ the recess 23 c are tapered towards the slot 26. The said bracket could be made of steel and the said slot is formed in the said back wall of said bracket by pressing. The slot 26 is defined by a front wall 25 and side walls 25a. The bracket 22 is resistance welded to the flat surface [13,50] pf the lower shell 12 at the spots marked 17. The mounting arrangement also includes a compressible holder 27 particularly seen in figure 11 of the drawings,. The holder has a holding formation 24 which is adapted to encompass an overload protector seen in figure 12 in its operative configuration . In the example illustrated, the protector body is cylindrical, hence the holding formation is in the form of a ring. But the holding formation will take the shape of the outer body and dimensions of the protector body. Thus if the outer body is made cuboid then the formation may be rectangular. The holder as seen in figure 12 has a step 17 at the base and the protector 16 for mounting is slipped into the formation 24 till this step 17. The the said holder has resilient prongs 28 extending therefrom said prongs adapted to be resiliently deformed and snap fit in the formed slot 26 of the rigid bracket 22. The holder is typically made of a synthitc polymeric material or bakelite. A seen in figure 11, the free ends 28a of the prongs are provided with teeth formations 29, said teeth formations having notches which latch on the said side walls 25a of the slot 26 in the operative configuration of the mounting arrangement. The said bracket is provided with side walls 23 b extending from the bracket which protect the overload protector mounted in the operative configuration of the arrangement as seen in figure 14. Figure 15 depicts the temperature (in °C) vs time (in minutes) for the comparison of response time of overload protector in prior art and present invention. For experimental verification, 20 number of compressors were tested in the laboratory to observe the change in response time of the overload protector due to change in position. The line for the overload protector according to prior art is shown by O and line for overload protector according to present invention is shown by N. The graph shows that substantial improvement was observed in the Response Time of Overload Protector according to the present invention for range of varied temperature of the Shell. The improvement in the Response Time of the overload protector observed was of the order of 20 to 40% as shown in the Graph. Experimental results have shown that by the use of the arrangement of this invention for sensing body temperature of the shell there is a 100 per cent positive contact between the protector and the shell and the temperature is sensed 20 to 40% quicker. Thus when the temperature of the shell exceeds safe limits, typically above 80 to 120 degrees Celsius the sensing is quicker and the compressor is therefore protected. Advantages: 1. The improvement in protection response time of the overload protector by 20 to 40% with respect to temperature, thus protecting compressor running at unintended conditions. 2. Improved reliability i.e. reduction in the field failure of the compressor due to efficient protection. 3. Ease of assembly of the overload protector with compressor protector bracket. 4. Cost benefits due to material cost reduction of the protector bracket. We Claim: [1] A mounting arrangement for an external over load protector device for a hermetic compressor housed in body consisting of an upper and a lower shell and a hermetic terminal extending from the lower shell; said mounting arrangement comprising a. a rigid bracket [22] with a formed slot [26], said rigid bracket [22] adapted to be mounted on the flat surface [13,50] of the lower shell [12] of the body of the compressor, below the said hermetic terminal [14] and; b. a compressible holder [14] adapted to encompass an overload protector in its operative configuration, the said holder having resilient prongs [28] extending therefrom said prongs adapted to be resiliency deformed and snap fit in the formed slot of the rigid bracket. [2] A mounting arrangement for an external over load protector device for a hermetic compressor as claimed in claim 1, in which said bracket is made of steel and the said slot is formed in the said bracket by pressing. [3] A mounting arrangement for an external over load protector device for a hermetic compressor as claimed in either claim 1 or claim 2, in which the bracket is defined by an operational back wall (23a) and a recess (23c) is cut in the said back wall and the slot (26) is formed in the said recess. [4] A mounting arrangement for an external over load protector device for a hermetic compressor as claimed in claim 3, in which the recess (23 c) has side walls which taper towards the slot. [5] A mounting arrangement for an external over load protector device for a hermetic compressor as claimed in any one of the preceding claims, in which the said slot (26) is defined by a front wall (25) and side walls (25a). [6] A mounting arrangement for an external over load protector device for a hermetic compressor as claimed in any one of the preceding claims, in which the holder is ring shaped (Figure 11).) [7] A mounting arrangement for an external over load protector device for a hermetic compressor as claimed in claim 1, in which the free ends (28a) of the prongs are provided with teeth formations (29), said teeth formations having notches which latch on said side walls of said slot in the operative configuration of the mounting arrangement. [8] A mounting arrangement for an external over load protector device for a hermetic compressor as claimed in any one of the preceding claims in which the outer body of the overload protector is provided with a groove to securely accommodate the holder. [9] A mounting arrangement for an external over load protector device for a hermetic compressor as claimed in claim 1, in which the bracket is provided with side arms (23b) which protect the protector in its operative configuration. [10] A mounting arrangement for an external over load protector device for a hermetic compressor as described herein with reference to the accompanying drawings. Dated this 5th day of September, 2005. Mohan Dewan Of R. K. Dewan & Co Applicants' Patent Attorneys

Documents:

975-mum-2004-cancelled pages(2-2-2007).pdf

975-mum-2004-claims(granted)-(2-2-2007).doc

975-mum-2004-claims(granted)-(2-2-2007).pdf

975-mum-2004-correspondence(1-2-2007).pdf

975-mum-2004-correspondence(ipo)-(5-10-2007).pdf

975-mum-2004-drawing(8-9-2005).pdf

975-mum-2004-form 1(2-2-2007).pdf

975-mum-2004-form 13(22-1-2007).pdf

975-mum-2004-form 18(1-12-2005).pdf

975-mum-2004-form 2(granted)-(2-2-2007).doc

975-mum-2004-form 2(granted)-(2-2-2007).pdf

975-mum-2004-form 26(22-1-2007).pdf

975-mum-2004-form 3(10-9-2004).pdf

975-mum-2004-form 5(8-9-2005).pdf

975-mum-2004-form 9(14-9-2005).pdf

975-mum-2004-power of attorney(10-9-2004).pdf

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