Pumps – Motor driven – Electric or magnetic motor
Patent
1997-10-27
1999-09-28
Freay, Charles G.
Pumps
Motor driven
Electric or magnetic motor
417415, 417902, F04B 3504
Patent
active
059576715
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a refrigerant compressor, having an electric motor, the stator of which has windings with winding heads and the rotor of which drives a compressor which comprises a compressor block having an axially projecting bearing part for a rotor shaft, one winding head extending in the direction of the compressor block and electrical insulation being provided between the winding head and the compressor block.
Such refrigerant compressors are widely used in domestic refrigerators, that is, in refrigerators or freezers. In these cases, one would like to have as much space as possible for the cooling chamber, which requires the refrigerant compressor to be made as small as possible.
Refrigerant compressors have therefore already become known, (U.S. Pat. Ser. No. 3,306,524) the diameter of which is determined essentially only by the diameter of the motor and the height of which is determined by the sum of the heights of motor and compressor. The electrical insulation in that case is provided by a shell, which is secured to the winding head of the stator winding that is next to the compressor block. Securing this shell to the winding head is difficult, however. During assembly, there is a danger that the shell will be pushed out of its desired position. Moreover, the shell covers only a small part of the winding head, so that electrical safety can be guaranteed only if there is an adequate distance between the uncovered parts of the winding head and the compressor block.
The reduction in the overall size of such refrigerant compressors leads to a reduction in efficiency. A prime cause of this reduction in efficiency is attributable to electric losses in the motor.
The problem on which the invention is based is to be able to improve the efficiency of the refrigerant compressor with the same overall size, without substantially increasing the work involved in assembly.
SUMMARY OF THE INVENTION
That problem is solved in a refrigerant compressor of the kind mentioned in the introduction in that the insulation is formed by a film which is pushed with a substantially centrally arranged opening onto the bearing part.
The film is, of course, electrically insulating. Because it is used in an encapsulated refrigerant compressor, it must also be resistant to the refrigerant used therein. The film is pushed onto the bearing part and thereby fixed to the compressor block. It covers over the compressor block so that the winding head can now be relatively generously enlarged without the risk of electrical contact between the winding head and the compressor block. By enlarging the winding head, electric losses can be reduced and thus efficiency increased. The work involved in assembly is only slightly increased. As an additional step the foil has to be pushed onto the bearing part. The refrigerant compressor can then be assembled in the customary manner. No heed need be paid, however, to ensuring that the winding head of the stator winding maintains a certain distance from the compressor block.
This again simplifies assembly, because the stator can be secured to the compressor block without more specific spacing requirements. The film does not have a distinct three-dimensional shape. On the contrary, it adapts itself to the winding head so that even with a simple construction a relatively safe electrical insulation is achieved.
The film preferably lies under a predetermined pre-stress against the circumference of the bearing part. By being pushed onto the bearing part it is, as it were, fixed to the compressor block. This facilitates further assembly. Moreover, in operation this prestress also guards against the film coming loose from its given position and leading to unpredictable electrical states in operation.
The film preferably consists of a flexible material having a predetermined stiffness. It thus adapts itself extremely well to the winding head. Moreover, only negligible forces are required to push it onto the bearing part. In its installed and deformed state, the film ten
REFERENCES:
patent: 3306524 (1967-02-01), Matuki et al.
patent: 4725334 (1988-02-01), Brimm
Danfoss Compressors GmbH
Freay Charles G.
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