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Axial bearing arrangement in a hermetic compressorRelated Patent Categories: Pumps, Motor Driven, Axial Thrust Balancing Means For Rotary Pump And MotorAxial bearing arrangement in a hermetic compressor description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070166175, Axial bearing arrangement in a hermetic compressor. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD OF THE INVENTION [0001] The present invention refers to an axial bearing arrangement in a reciprocating hermetic compressor with vertical shaft of the type used in small refrigeration systems. BACKGROUND OF THE ART [0002] Hermetic compressors of refrigeration present, mounted inside a hermetically sealed shell a cylinder block, supporting a vertical crankshaft to which is mounted the rotor of an electric motor. The weight of the crankshaft-rotor assembly is supported by an axial bearing, generally in the form of a flat sliding axial bearing in which an oil film guarantees the separation of the surfaces with mutual relative movement (slipping), or in the form of a roller bearing (U.S. Pat. No. 4,632,644; WO03/019008) in which a ball assembly supports the axial weight, rolling on races that resist the Hertz tensions developed by contact with the balls. [0003] The crankshaft carries, in its lower end, a pump rotor, which during the operation of the compressor conducts lubricant oil from a reservoir defined in the lower portion of the shell to the parts with mutual relative movement so as to guarantee oil supply for the correct operation of said parts. [0004] The position of the axial bearing may vary according to the arrangement of the compressor components and to design variations. In some solutions, the rotor is mounted to the crankshaft below the cylinder block, as illustrated in FIG. 1, or the rotor is mounted to the crankshaft above the cylinder block, as illustrated in FIG. 2. Depending on the mounting position of the rotor in relation to the cylinder block, the surfaces that define the axial bearing are altered. [0005] In the situation in which the rotor is mounted below the cylinder block, the lower surface of an annular flange of the crankshaft axially journals on an annular surface defined in the upper end of the radial bearing hub. On the other hand, when the rotor is mounted above the cylinder block, the lower face of the rotor axially journals on an annular surface defined in the upper end of the radial bearing hub. [0006] It is also known the arrangement in which a second bearing (external bearing) is provided, radially actuating on the crankshaft. In this construction in which the shaft extends beyond the eccentric part, the lower face of the annular flange can axially journal on an upper annular surface of said second radial bearing, as illustrated in FIG. 3 for a specific arrangement in which the rotor is mounted below the cylinder block. [0007] In the constructions described above in relation to a sliding axial bearing, the perfect parallelism between the mutually confronting surfaces which define the axial bearing is not guaranteed due to the presence of position errors (axial strikes) and mainly deformations of the components during the compressor operation. [0008] These errors and deformations give rise to a geometry which is unfavorable to the formation of an oil film and which consequently reduces the supporting capacity of the axial bearing, increasing the mechanical friction losses and wear to the surfaces. [0009] The improvement of the energetic performance of these compressors can be achieved by reducing the mechanical friction losses, for example by employing more efficient bearings in the form of a roller axial bearing, whose operation in terms of dissipated mechanical loss presents rates close to the ideal. A constructive solution of a bearing using this concept is described in Brazilian patent PI8503054 (U.S. Pat. No. 4,632,644) related to hermetic compressors in which the rotor of the electric motor is mounted above the cylinder block, as illustrated in FIG. 2. [0010] The provision of a roller axial bearing as suggested in U.S. Pat. No. 4,632,644 can increase noise and reduce the mechanical reliability of the compressor, depending on the configuration of the axial bearing and on its mounting arrangement. [0011] Co-pending document WO03/019008 of the same applicant refers to a hermetic compressor having the rotor of the electric motor mounted to the crankshaft below the cylinder block and presenting a roller axial bearing arrangement which increases the mechanical reliability of the roller bearing by minimizing the effects of crankshaft deflection, as illustrated in FIG. 4. OBJECTS OF THE INVENTION [0012] It is a generic object of the present invention to provide a bearing arrangement in a reciprocating hermetic compressor of refrigeration, which can reduce mechanical losses and total noise levels, resulting in better energetic performance of the hermetic compressor. [0013] It is a further object of the present invention to provide a bearing arrangement such as mentioned above, which does not impair the adequate lubrication of the crankshaft portion and of the other components of the compressor mechanism located above the axial bearing. SUMMARY OF THE INVENTION [0014] The present bearing arrangement is applied to a reciprocating hermetic compressor, comprising: a cylinder block mounted inside a shell and carrying a cylinder and a vertically disposed radial bearing hub; a crankshaft mounted through the radial bearing hub and having a first end portion projecting outwardly from the radial bearing hub and securing a rotor of an electric motor, and an opposite second end portion projecting outwardly from the radial bearing hub and incorporating a peripheral flange and an eccentric portion, the arrangement of the present invention comprising at least one magnetic axial bearing assembly composed of magnet elements with mutually confronting faces and with magnetic orientation to produce in a normal operation, support for the crankshaft sufficient to guarantee the inexistence of contact between the confronting faces of the magnet elements that define the axial bearing, each magnet element being mounted in a respective part associated with a rotating component (crankshaft or any component rigidly connected thereto, such as the rotor), and the other part being associated with a fixed component (cylinder block or any component rigidly connected thereto, such as the external bearing for example), i.e., each magnet element is mounted to a respective part of at least one of the pairs of parts of crankshaft and cylinder block and of cylinder block and rotor, there being provided, in at least one of the pairs of parts, confronting mechanical stops which are maintained spaced apart by an axial gap (FA) smaller than a magnetic axial gap (FM) existing between the confronting faces of the magnet elements, in order to guarantee that, upon occurring at least one of the conditions of a sufficiently high increase of the compressor temperature and an axial displacement of said parts during transportation of the compressor causing the mutual seating of the confronting mechanical stops, the magnetic axial gap is maintained higher than zero. Due to the presence of the magnetic axial gap, the present invention incorporates an oil deflecting means that guarantees an ascending oil flow to lubricate the tribologic pairs located above the magnetic axial bearing. BRIEF DESCRIPTION OF THE DRAWINGS [0015] The invention will be described below with reference to the enclosed drawings, in which: [0016] FIG. 1 is a median vertical sectional view of a reciprocating hermetic compressor with the vertical crankshaft affixed to an electric motor rotor disposed below the cylinder block and vertically supported by a prior art axial bearing; [0017] FIG. 2 is a view similar to that of the previous figure, but illustrating a prior art construction in which the rotor of the electric motor is positioned above the cylinder block and vertically supported by a prior art roller axial bearing; [0018] FIG. 3 is a median vertical sectional view of a reciprocating hermetic compressor similar to that of FIG. 1 and which is provided with an external bearing actuating radially on an extension of the crankshaft external to its eccentric portion and vertically supported by an axial bearing; [0019] FIG. 4 is a partial vertical sectional view of a cylinder block of the type illustrated in FIG. 1 and incorporating a vertical radial bearing hub, in whose upper end a roller axial bearing is seated to the crankshaft-electric motor rotor assembly, as taught in the prior art; Continue reading about Axial bearing arrangement in a hermetic compressor... Full patent description for Axial bearing arrangement in a hermetic compressor Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Axial bearing arrangement in a hermetic compressor patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Axial bearing arrangement in a hermetic compressor or other areas of interest. ### Previous Patent Application: Statically sealed high pressure fuel pump and method Next Patent Application: Linear compressor Industry Class: Pumps ### FreshPatents.com Support Thank you for viewing the Axial bearing arrangement in a hermetic compressor patent info. 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