Pump for the drain outlet of washing machines

Details Pump for the drain outlet of washing machines Pump for the drain outlet of washing machines

2000-03-13

2001-07-24

Walberg, Teresa (Department: 3742)

Pumps

Motor driven

Electric or magnetic motor

C134S104100

Reexamination Certificate

active

06264441

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to an improved pump, particularly for use in the drain outlet of washing machines or the like.
A pump driven by a permanent-magnet synchronous motor is more and more frequently installed in these machines; owing to its characteristics, it certainly achieves the goal of reducing costs and consumption, but it suffers several problems.
In the field of washing machines, manufacturers have developed technical specifications which take into account a wide range of situations, linked in particular to blockages or clogging, or in any case to difficulty in draining.
One of the main problems is linked to the water, which contains detergent foam in an amount which is inversely proportional to the hardness of the water, and to the fact that the user quite often introduces excessive doses of detergent.
The presence of a large amount of foam leads to cavitation of the impeller inside its chamber, with consequent difficulties in draining.
Many technical specifications further require that various types of objects that can be present in the items that are washed must be able to pass through the pump.
For example, socks, sponges of various kinds, metallic coins, hairpins, chains, toothpicks or other objects of this type and size must be able to pass through a drain outlet pump without jamming.
Moreover, lint or threads which are always present in the drain water of a washing machine can coil around the shaft of the motor, blocking it.
SUMMARY OF THE INVENTION
The aim of the present invention is to provide an improved pump which can operate without clogging even in difficult conditions.
Within the scope of this aim, an object of the present invention is to provide a pump which is capable of draining the water of a washing machine even if it contains a considerable amount of foam.
Another object of the present invention is to provide a pump which can expel products of various kinds that are present in the washing water.
Another object of the present invention is to provide a pump in which the motor shaft is protected, preventing string-like products from coiling around it.
Another object of the present invention is to provide a pump which has a good hydraulic performance and accordingly a low electrical power consumption.
This aim, these objects and others which will become apparent hereinafter are achieved by an improved pump for the drain outlet of washing machines, comprising a synchronous permanent-magnet electric motor which is associated, by means of a flange, with a dome which forms a chamber for an impeller, characterized in that it comprises an impeller with is radial vanes which are associated with a perforated disk provided with a plurality of pressure-compensating vanes on a motor side of the disk, a dome which forms the chamber of the impeller, an intake duct which has an elliptical cross-section with a median axis which is parallel to an axis of the impeller but is axially offset on an opposite side with respect to a discharge duct, which also has an elliptical cross-section, with a radiused inlet which has the local internal configuration of said dome.


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