Title of Invention

AN IMPROVED PROCESS OF MANUFACTURING A MUFFLER FOR HERMETIC COMPRESSORS AND TO A MUFFLER MANUFACTURED BY THE METHOD

Abstract

An improved process of manufacturing muffler for hermetic compressors consists of the steps: a) manufacturing body of the muffler in a cylindrical shell form having one end closed and the other end open, the said open end being flared out to form a cup shaped collar, the closed end having an opening for internal pressure relief valve adaptor and the side wall of the body having an opening for discharge connector tube, b] manufacturing other components of the muffler, c] forming a subassembly of the body, discharge connector tube and internal pressure relief valve adaptor; d] forming another sub-assembly of the cover plate, threaded adaptor and the impedance tube: cleaning the said two sub-assemblies for removing any rust and dust; and welding the said two sub-assemblies together at the cup shaped collar portion of the body, with the help of a fixture, using projection resistance welding process.

Full Text

FORM-2 THE PATENTS ACT, 1970 (39 of 1970) & THE PATENTS RULES, 2003 COMPLETE Specification {See section 10 and rule 13) AN IMPROVED PROCESS OF MANUFACTURING A MUFFLER FOR HERMETIC COMPRESSORS AND TO A MUFFLER MANUFACTURED BY THE METHOD KIRLOSKAR COPELAND LTD. of 1202/1, Ghole Road, Pune 411 005, Maharashtra, India, an Indian Company THE FOLLOWING SPECIFICATIO PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED:- This invention relates to an improved process of manufacturing a muffler for hermetic compressors and to a muffler manufactured by the method. In the prior art mufflers for hermetic compressors, generally used in refrigeration and air conditioning systems, are typically made by using the furnace-brazing process. The conventional furnace brazed muffler mainly comprises a cylindrical body open at two ends made from a tube a bottom cap/cover with its skirt extending over the side wall of the body provided at the bottom end of the body, an opening having neck projecting downward provided in the said bottom cover, a threaded adapter of discharge muffler provided in the said opening an impedence tube fitted in the said adaptor a discharge connector tube fitted in the side opening of the body near its top end and internal pressure relief valve adaptor for providing internal pressure relief valve is fitted in the depressed top cover, all the components being fixed by interference fit and furnace brazed. The existing process of manufacturing muffler for compressors using furnace brazing comprises the following steps: (i) Preparing all components of the muffler independently by suitable manufacturing process. Like the body of the muffler is formed from the tube or the steel sheet. (ii) Cleaning of all components with suitable chemicals ensuring that all the components are free from rust and dust and loose particles. 2 (iii) Fixed to each other by interference fit method at the desired location. (iv) Once the assembly is ready before brazing the copper wire or paste is applied. (v) The assembly with copper applied at desired location passing through the furnace or kept in the furnace having inert atmosphere and having temperature above the melting point of copper is about 1000°C in the furnace the muffler assembly is passed through different temperature zones before melting and after melting of copper. (vi) The complete brazed muffler cooling at very slow rate, so that oxidation is avoided after he brazing operation is completed. The disadvantages of the conventional furnace brazing process are as follows: - a) The cost of maintaining an inert atmosphere is very high in furnace required for brazing b) The cost of furnace maintenance is high compared to welding process. c) The joint design has to be very good, since there is no control while the filler copper metal is melting. d) The defects in the brazed joints can only be detected after completion of furnace brazing e) It is very difficult to maintain the geometrical relations of the assembly components; it needs very high cost equipment to obtain dimensional consistency. 3 f) The leakage or any flaw in the brazed joint cannot be repaired after furnace brazing. g) The leak testing is only possible with the help of dry air or nitrogen or helium, which is a very costly process since leak detection is possible only through very complicated leak test rig. The main object of this invention is to obviate the above mentioned disadvantages or short corning of the existing process of manufacturing a muffler for compressors and to provide an improved process of manufacturing the muffler for compressors which is cost effective and gives a very high production rate, Besides, there is no need for costly equipments, no need of filler material no need of maintaining an inert atmosphere and at the same time the process provides high geometrical accuracies of the components and high strength of the joints. Accordingly the invention provides a improved process of manufacturing muffler for hermetic compressors comprising the steps: a) manufacturing body of the muffler in a cylindrical shell form having one end closed and the other end open, the said open end being flared out to form a cup shaped collar, the closed end having an opening for internal pressure relief valve adaptor and the side wall of the body having an opening for discharge connector tube, b) manufacturing other components of the muffle, such as discharge connector tube, internal pressure relief vale adaptor, internal pressure 4 relief valve, impedance tube, threaded adaptor of discharge muffler and cover plate. c) forming a subassembly of the body, discharge connector tube and internal pressure relief valve adaptor. d) forming another sub-assembly of the cover plate, threaded adaptor and the impedance tube: e) cleaning the said two sub-assemblies for removing any rust and dust; and f) welding the said two sub-assemblies together at the cup shaped collar portion of the body, with the help of a fixture, using projection resistance welding process. Typically in the improved process for manufacturing Muffler, the said body is manufactured from steel sheet by deep drawing technique. Typically in the two sub-assemblies are formed separately by brazing preferable by silver brazing. Typically the two sub-assemblies are thoroughly washed preferably by using chemicals for removing my rust and dust. Typically the said two sub - assemblies after cleaning/washing are coated with iron phosphate coating. Typically the said cover plate is tapered at the periphery by an angle ranging from 1° to 5° the opening of the cover plate for joining threaded adapter is 5 having inside taper of 1° to 3° and the adaptor in the mating portion is having a chamber of 40° to 60°' Typically the said fixture used for projection resistance welding comprises a right angled block provided with a hole and an adjacent slot for accommodating the muffler assembly, a split electrode consisting of a fixed electrode and a moving electrode, adopted to surround the cup shaped collar of the body, mounted at the top of the said bloc, another electrodes made in the form of hollow tubular body according to the size of the cover plate, supply links connected to each electrode for supplying electric current, hydraulic /pneumatic mechanical device connected to the moving electrode, for providing linear movement tote moving electrode, the fixed electrode provided with tubes for cooling the electrodes and a handling provided with each part of the said electrodes. According to another aspect of this invention, Typically a muffler for hermetic compressors generally used in refrigeration and air conditioning systems, manufactured by the process comprising a cylindrical body integrally closed at one end the other open end flared outward forming a cup shaped collar an internal pressure relief valve adopted to be mounted in an internal pressure relief valve adapter fitted in an opening provided in the integrally closed end of the body by brazing process, a discharge connector tube fitted in the side opening of the body by braizing process an impedance to be fitted to a threaded adopter brazing the said threaded adapter fitted in an opening of a cover plate by brazing and the said cover plate fitted inside the cup shaped collaret the open end of the said body by projection 6 resistance welding providing weldments at eth entire peripheral joint of the cover plate and body. The invention will now be described with reference to the accompanying drawing wherein: Fig 1: - shows in exploded perspective view a conventional muffler known in the prior art. Fig 2: - shows in sectional view the muffler assembly manufactured by furnace brazing process as per prior art. Fig 3: - shows in exploded perspective view a muffler for compressors according to this invention. Fig 4: - shows in perspective view the muffler assembly according to this invention. Fig 5: - shown in sectional view the muffler assembly manufactured by projection resistance welding process according to this invention. Fig 6A & Fig 6B: - show partially the bottom cover plate of the muffler before an after projection resistance welding with the body. Fig 7 & 8: - show the side view and top view respectively of the projection resistance-welding fixture for welding the muffler according to this invention. 7 Fig 9 & 10: - show in perspective views the fixture set up for muffler welding according to this invention. Fig 11:- shows the details of the electrode construction and use. Fig 12A & 12B: - show in plan and side view the lower electrode with pressure device. Referring to Figs 1& 2 the conventional muffler mainly comprises a cylindrical body 1 made in the form of a tube, which is open at both ends. A bottom cap/cover 4 is placed from outside and a top cover/cap 8 is fitted from inside the body. The bottom cap is fitted with a threaded adaptor 2 of discharge muffler holding impedance tube 9and the top cap8 is fitted with internal pressure relief valve adaptor 7. A discharge connector tube 3 is fitted in the sidewall of the bodyl. All these components are cleaned and fixed to each other by interference fit. The copper wire or paste is applied at the joints and the assembly is passed through the brazing furnace having inert atmosphere. Different temperature zones are maintained inside the furnace before melting zone having a temperature of about 100° C. Brazed muffler having furnace-brazing joints 10 is cooled at a very slow rate to avoid oxidation. The disadvantage associated with conventional process of muffler manufacturing, using furnace brazing has been described herein before. 8 Now referring to Fig 3 to Fig 12B the improved process of manufacturing Muffler according to this invention comprises the following steps: - (a) Manufacturing the body 1A of the muffler from the steel sheet preferably by deep drawing technique such that the cylindrical body/shell is having one end IB closed and the other end 1C open, The open end is flared out forming a cup shaped collar, which is adopted to be closed by a cover plate 4a-using projection resistance welding process as described hereinafter. An opening is provided in the sidewall of the body for discharge connector tube 3. The necessity of fixing top cover 8 as needed in the prior art muffler is eliminated and the closed end Ib of the body is provided with an opening for internal pressure" relief valve adaptor 7 (b) Other components like discharge connector tube 3, impendence tube 9, internal pressure relief valve 6, internal pressure relief valve adaptor 7, bottom threaded adaptor 2 of discharge muffler, bottom cover plate 4A are manufactured, separately in the usual manner. (c) The subassembly of the body 1A, discharge connector tube 3 and internal pressure relief valve (IPRV) adaptor 7 is carried out separately preferably by using silver brazing 11. (d)The subassembly of bottom cover plate 4A and bottom threaded adaptor 2 and impedance tube 9 is carried out separately preferably by using silver brazing 11. (e) These two subassemblies are washed thoroughly for removing any rust and dust preferably by using suitable chemicals and are coated with iron phosphate coating. 9 (f) These two subassemblies are welded together at the cup shaped collar portion by using a fixture and projection resistance welding process. According to this invention projection resistance welding process is used for welding the two subassemblies of the muffler. Resistance welding is a process used to join metal parts with the electric current. The various forms of resistance welding known are spot welding, seam welding, projection welding and butt-welding. In all these forms of resistance welding, the parts are locally heated until a molten pool is formed. The parts are then allowed to cool and the pool freezes to form a weld nugget/joint. According to this invention instead of nugget shaped weldment the entire peripheral joint of the bottom cover plate and the body is provided a weldment 5. The cup shaped end 1C of the body 1A is provided with desired fillest radius to accommodate bottom cover plate. The bottom cover plate 4A is having its periphery tapered by an angle ranging fro 1° to 5°. In the joined portion of bottom cover plate 4A and bottom threaded adaptor 2, the opening of bottom cover plate has an inside taper of 1° to 3° and the adaptor has in mating portion a chamfor of 40° to 60°. For projection resistance welding to create heat, copper electrode pass an electric current through the work pieces. Heat generated depends on the electrical resistance and thermal conductivity of the metal and the time that current is applied. Copper is used for the electrode because it has low resistance and high thermal conductivity compared to most metals. This ensures that the heat is generated in the work pieces instead of the electrodes. The fixtures used are generally made of brass. 10 The fixture used for carrying out the projection resistance welding of the muffler is shown in Fig. 7 to 12B and mainly comprises a right angle block 14 provided with a rib 13 and a hole 15 for accommodating therein the muffler assembly 16. A slot 17 is also providing in the block 14 adjacent to the hole 15, for accommodating therein discharge connector tube 3. Split type electrode 12 is mounted on the block 14 around the hole 15. The electrode 12, which surrounds the cup shaped end 1C of the muffler, consists of a fixed electrode 12A and a moving electrode 12B, splitted from the center line of the lower circular electrode assembly 12. Each part of the lower electrode is provided with a handle 20. The upper electrode 18 is made in a hollow circular tubular body form according to the size of the cover plate 4a. The fixed electrode part 12A is provided with tubes 12C for electrode cooling and the moving electrode part 12B is attached to pneumatic /hydraulic /mechanical device 12D for providing linear movement to it. Supply links 19 are provided for supplying electric current to the lower and upper electrode. The Advantages of projection welded Mufflers. a) Proposed inventive method of Muffler construction with Projection welding eliminates need of top cover since top cover formed from the body itself. b) The production rate is very high compared to furnace -brazed muffler. c) No filler material is required at the welding joint. d) No need of inert atmosphere during welding since welding cycle time is very short. 11 e) The geometrical accuracies are maintained, since there is control over muffler components sub assembly. f) The leak testing of the muffler assembly can be done in appropriate chemical bath where water is used as a solvent. g) The projection welding fixtures are very cost effective, resulting in the less cost of the equipments required. h) The strength of the welded joint is equal or more compared to brazed joint. The above description with reference to drawing given just to understand the invention rather than to limit its scope 12 We Claim - 1) An improved process of manufacturing muffler for hermetic compressors comprising the steps: a) manufacturing body of the muffler in a cylindrical shell form having one end closed and the other end open, the said open end being flared out to form a cup shaped collar, the closed end having an opening for internal pressure relief valve adaptor and the side wall of the body having an opening for discharge connector tube; b) manufacturing other components of the muffle, such as discharge connector tube, internal pressure relief vale adaptor, internal pressure relief valve, impedance tube, threaded adaptor of discharge muffler and cover plate; c) forming a subassembly of the body, discharge connector tube and internal pressure relief valve adaptor; d) forming another sub-assembly of the cover plate, threaded adaptor and the impedance tube; e) cleaning the said two sub-assemblies for removing any rust and dust; and f) welding the said two sub-assemblies together at the cup shaped collar portion of the body, with the help of a fixture, using projection resistance welding process. 2) A process for manufacturing Muffler as claimed in claim 1, in which the said body is manufactured from a steel sheet by deep drawing technique. 13 3) A process for manufacturing Muffler as claimed in claim 1, in which the two sub-assemblies are formed separately by brazing preferable by silver brazing. 4) A process for manufacturing Muffler as claimed in claim 1, in which the two sub-assemblies are thoroughly washed preferably by using chemicals for removing rust and dust and after cleaning/washing are coated with iron phosphate coating. 5) A process for manufacturing Muffler as claimed in claim 1, in which the said cover plate is tapered at the periphery by an angle ranging from 1° to 5° the opening of the cover plate for joining threaded adapter is having inside taper of 1° to 3° and the adaptor in the mating portion is having a chamber of 40° to 60° 6) A process for manufacturing Muffler as claimed in claim 1, in which the said fixture used for projection resistance welding comprises a right angled block provided with a hole and an adjacent slot for accommodating the muffler assembly, a split electrode consisting of a fixed electrode and a moving electrode, adopted to surround the cup shaped collar of the body, mounted at the top of the said bloc, another electrodes made in the form of hollow tubular body according to the size of the cover plate, supply links connected to each electrode for supplying electric current, hydraulic/pneumatic mechanical device connected to the moving electrode, for providing linear movement tote moving electrode, the fixed electrode provided with tubes for cooling the electrodes and a handling provided with each part of the said electrodes. 14 7) A process for manufacturing Muffler as claimed in claim 1, substantially as herein described and illustrated in Fig 3 to 12b of the accompanying drawings. 8) A muffler for hermetic compressors generally used in refrigeration and air conditioning systems manufactured by the process claimed in claims 1 to 7 comprising a cylindrical body integrally closed at one end the other open end flared outward forming a cup shaped collar an internal pressure relief valve adopted to be mounted in an internal pressure relief valve adopted to be mounted in an internal pressure relief valve adapter fitted in an opening provided in the integrally closed end of the body, by brazing process, a discharge connector tube fitted in the side opening of the body by braizing process an impendence tube fitted to a threaded adaptor by brazing the said threaded adapter fitted in an opening of a cover plate by brazing and the said cover plate fitted inside the cup shaped collar at the open end of the said body by projection resistance welding providing weldment at the entire peripheral joint of the cover plate and body 9) A muffler for hermetic compressors substantially as herein described and illustrated in figs 3 to 12b of the accompanying drawings. 15

Documents:

63-mum-2005-abstract(20-1-2005).doc

63-mum-2005-abstract(20-1-2005).pdf

63-MUM-2005-ABSTRACT(22-6-2011).pdf

63-MUM-2005-ABSTRACT(8-6-2011).pdf

63-mum-2005-claims(20-1-2005).doc

63-mum-2005-claims(20-1-2005).pdf

63-MUM-2005-CLAIMS(AMENDED)-(22-6-2011).pdf

63-MUM-2005-CLAIMS(AMENDED)-(8-6-2011).pdf

63-MUM-2005-CLAIMS(AMENDED)-(9-10-2014).pdf

63-MUM-2005-CORRESPONDENCE(11-10-2010).pdf

63-mum-2005-correspondence(18-3-2008).pdf

63-MUM-2005-CORRESPONDENCE(28-1-2014).pdf

63-MUM-2005-CORRESPONDENCE(6-12-2013).pdf

63-MUM-2005-CORRESPONDENCE(6-8-2010).pdf

63-MUM-2005-CORRESPONDENCE(8-11-2011).pdf

63-mum-2005-description(complete)-(20-1-2005).pdf

63-mum-2005-drawing(20-1-2005).pdf

63-MUM-2005-DRAWING(22-6-2011).pdf

63-mum-2005-form 1(20-1-2005).pdf

63-MUM-2005-FORM 1(22-6-2011).pdf

63-MUM-2005-FORM 1(8-6-2011).pdf

63-MUM-2005-FORM 1(9-10-2014).pdf

63-mum-2005-form 13(22-1-2007).pdf

63-mum-2005-form 13(22-6-2011).pdf

63-mum-2005-form 18(18-3-2008).pdf

63-mum-2005-form 2(20-1-2005).doc

63-mum-2005-form 2(20-1-2005).pdf

63-mum-2005-form 2(title page)-(20-1-2005).pdf

63-MUM-2005-FORM 2(TITLE PAGE)-(22-6-2011).pdf

63-MUM-2005-FORM 2(TITLE PAGE)-(8-6-2011).pdf

63-MUM-2005-FORM 2(TITLE PAGE)-(9-10-2014).pdf

63-mum-2005-form 26(20-1-2005).pdf

63-MUM-2005-FORM 26(22-6-2011).pdf

63-mum-2005-form 3(20-1-2005).pdf

63-MUM-2005-FORM 3(22-6-2011).pdf

63-mum-2005-general power of attorney(20-1-2005).pdf

63-MUM-2005-MARKED COPY(22-6-2011).pdf

63-MUM-2005-MARKED COPY(8-6-2011).pdf

63-MUM-2005-MARKED COPY(9-10-2014).pdf

63-MUM-2005-POWER OF ATTORNEY(9-10-2014).pdf

63-MUM-2005-REPLY TO EXAMINATION REPORT(22-6-2011).pdf

63-MUM-2005-REPLY TO EXAMINATION REPORT(8-6-2011).pdf

63-MUM-2005-REPLY TO HEARING(9-10-2014).pdf

63-MUM-2005-SPECIFICATION(AMENDED)-(22-6-2011).pdf

63-MUM-2005-SPECIFICATION(AMENDED)-(8-6-2011).pdf