Axial bearing arrangement in a hermetic compressor

Abstract

A magnetic axial bearing arrangement in a reciprocating hermetic compressor, comprising: a cylinder block (20) and a radial bearing hub (40); a crankshaft (50) securing a rotor (61) of an electric motor (60), said arrangement comprising at least one magnetic axial bearing assembly (100) formed of a pair of magnet elements (101), a magnet element (101) of each pair being mounted to a respective part of at least one of the pairs of parts of crankshaft (50) and cylinder block (20), of cylinder block (20) and rotor (61), or of crankshaft (50) and external bearing (120), the parts of at least one of the pairs of parts carrying respective confronting mechanical stops which are maintained spaced apart by an axial gap (FA) smaller than a magnetic axial gap (FM) higher than zero and to be maintained between the magnet elements (101) of a magnetic axial bearing assembly (100).

Description

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 o...

AI Technical Summary

Benefits of technology

[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

Problems solved by technology

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.

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.

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.

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