GB2230567A - Hermetic motor compressor - Google Patents

Abstract

A reciprocating, hermetic motor compressor (10) of vertical shaft type for refrigerating apparatus comprises a casing (11) which contains an electric motor (12) arranged in the upper part of the casing and fixed to a compressor unit (13) thereunder. The unit includes a bush (21) which receives a vertical shaft (19) driven by the motor (12). A radial bearing (22), adapted to support limited axial loads, is disposed in the bush (21) in the proximity of the motor and co-operates with the shaft to change the friction thereof from sliding friction to rolling friction. <IMAGE>

Description

HERMETIC MOTOR COMPRESSOR The present invention relates to a hermetic motor compressor, especially for refrigerating apparatus.

Refrigerators and freezers intended for domestic aDplications incorporate small hermetic compressors which are, in general, reciprocating compressors of the vertical shaft type. To enhance the efficiency of the compressor, as well as improve the passage of gas through the various internal elements and increase the efficiency of the electric motor and of other components, it is possible to reduce the friction of the various moving members.

In reciprocating compressors having the electric motor assembly above the linkage, it is known to interpose, between the lower portion of the rotor of the motor and the upper portion of a bush receiving a drive output shaft to which the rotor is fixed, a shoulder washer which, during operation, allows the crawling between the rotor and the bush to be reduced. However this arrangement involves a considerable amount of friction with detriment to the efficiency of the compressor.

Also known is the use of an axial ball bearing instead of the steel washer between the movable rotor and the upper fixed portion of the bush. This results in a reduction of friction, but not to a sufficient extent to achieve a noteworthy improvement of the compressor efficiency.

It would thus be desirable to overcome these disadvantages, in particular by way of a coupling between motor and compressor unit which may reduce friction and noise, but without increasing cost.

According to the present invention there is provided a hermetic motor compressor comprising a casing, a reciprocating compressor unit arranged in the casing and provided with a bush, an electric motor arranged in the casing above the compressor unit and mounted on the unit, a substantially vertical shaft extending in the bush and drivingly coupling the motor to reciprocating means of the compressor unit, and a radial bearing arranged in the bush and in the region of the motor to accept limited axial loading and to co-operate with the shaft for translation of sliding friction of the shaft to rolling friction.

Preferably, the radial bearing, which is adapted to support even limited axial loads, is a ball bearing.

An embodiment of the present invention will now be more particularly described by way of example with reference to the accompanying drawing, the single figure of which is a partly sectional elevation of a motor compressor embodying the invention.

Referring now to the drawing, there is shown a reciprocating, hermetic motor compressor 10, of the vertical shaft type, comprising a casing 11 which contains an electric motor 12 in its upper part, and a compressor unit 13 thereunder on which the motor 12 is mounted.

The unit 13 is resiliently suspended, by means of springs 14, in the casing 11. A cylinder 15, closed by a head 16, is present in a block of the unit 13. A piston 17 is reciprocatingly movable in the cylinder 15 and is driven by means of a connecting rod 18, from a vertical shaft 19 which is fixed to a rotor 20 of the motor 12 and which is supported in a bush 21 mounted on the block of the unit 13. Fixed in the bush 21, in the proximity of the motor 12, is a radial ball bearing 22 co-operating with the shaft 19. A shoulder ring 23 is placed between the bearing 22 and the rotor 20.

The bearing 22, being a radial and not an axial bearing, changes the friction caused by the radial reaction of the shaft 19 from sliding friction to rolling friction. As the radial bearing 22 is capable of supporting even limited axial loads, and the load supported by the rotor 20 is completely supportable, the bearing supports even the axial load of the rotor.

The shaft 19 includes a duct 24 to convey the oil from the lower part of the casing 11 to the movable elements of the compressor unit for lubrication. Connected to the duct 24 is a passage 25 to convey the oil towards the bearing 22 for lubrication thereof when the motor compressor 10 is in operation.

The radial ball bearing 22 thus performs two functions: that of changing the friction caused by the radial reaction of the shaft 19 from sliding friction to rolling friction and that of supporting limited axial loads such as that caused by the rotor 20.

The overall efficiency of the motor compressor may thereby be increased and the use of the radial ball bearing may allow a recovery of lost Watts equivalent to 5-10% of the absorbed Watts.

Claims (4)

1. A hermetic motor compressor comprising a casing, a reciprocating compressor unit arranged in the casing and provided with a bush, an electric motor arranged in the casing above the compressor unit and mounted on the unit, a substantially vertical shaft extending in the bush and drivingly coupling the motor to reciprocating means of the compressor unit, and a radial bearing arranged in the bush and in the region of the motor to accept limited axial loading and to co-operate with the shaft for translation of sliding friction of the shaft to rolling friction.

2. A motor compressor as claimed in claim 1, wherein the radial bearing is a ball bearing.

3. A motor compressor substantially as hereinbefore described with reference to the accompanying drawings.

4. Refrigerating apparatus comprising a motor compressor as claimed in any one of the preceding claims.