Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2002-11-07
2004-04-20
Mullins, Burton (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S089000
Reexamination Certificate
active
06724111
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an anticondensation device particularly for electric motors.
As is known, a type of electric motor, for example a motor used in circulating pumps of heating systems, comprises a submerged rotor that is arranged within a corresponding enclosure arranged in turn inside stator windings contained in a box-like body.
The enclosure of the rotor is hermetic, so as to avoid infiltrations of the working fluid into the chamber formed by the box-like body that contains the stator windings, which must remain isolated.
Nevertheless, in normal operating conditions, owing to the difference in temperature between the inside of the box-like body, whose temperature is determined by the highest among the temperatures of the stator windings and of the working fluid, and the outside environment, any moisture of the air that is present inside said box-like body condenses at its inner wall.
In the worst case, this condensation causes problems in terms of reduction and/or lack of insulation between the phases of the stator windings and/or with respect to the ground connection, causing malfunctions.
An even worse problem arises if an electronic board is provided inside the motor for controlling its operation; such a board would inevitably be affected by the presence of internal condensate or water.
In order to obviate the problem of condensation formation inside the box-like body that contains the stator windings, drain openings are provided on its portion designed to be arranged at the lowest level and should allow the discharge of the condensation by gravity.
Furthermore, if the motor has an electronic control board, the container of such board, if provided, also has condensation drain openings at its portion bound to be arranged at the lowest level.
These openings must be sized and arranged in positions that ensure protection against water splashes, as prescribed by the EN 60259 standards related to the degrees of protection of enclosures, and in many cases installation positions of the motor itself are prohibited.
This solution, in any case, does not solve the problem of condensation formation, since the drain openings are indeed intended solely to discharge any condensation that has already formed inside the box-like body.
Another known constructive solution is to provide, over appropriate holes provided in the box-like body that contains the stator windings and/or the electronic board, a porous membrane that is permeable to water vapor and impermeable to water.
In this manner, ventilation is allowed inside the box-like body, allowing therefore the flow of warm air from the inside toward the outside of the box-like body, preventing formation of condensation.
However, this constructive solution is particularly complicated from the constructive standpoint and is expensive, because it is necessary to arranged the porous membrane over the holes of the box-like body.
SUMMARY OF THE INVENTION
The aim of the present invention is to solve or substantially reduce the problems of known types of anticondensation devices particularly for electric motors.
Within this aim, an object is to provide an anticondensation device that allows effective ventilation inside the box-like body that contains the stator windings.
Another object is to provide an anticondensation device that has a simple structure.
Another object is to provide an anticondensation device that also protects the motor against the infiltration of water splashes, as prescribed by the EN 60529 standards related to the degrees of protection of enclosures.
Another object is to provide an anticondensation device that can be assembled easily.
Another object is to provide an anticondensation device that has a low cost.
This aim and these and other objects that will become better apparent hereinafter are achieved by an anticondensation device particularly for electric motors, of the types that comprise a box-like body that contains the stator windings inside which the enclosure for a rotor is arranged hermetically, characterized in that it comprises a cover to be fixed over the bottom of said box-like body, so as to be spaced therefrom, in order to form an interspace and a perimetric air passage gap, said bottom being provided with through holes, corresponding first collars protruding perimetrically to said holes toward said cover and entering with play second collars that protrude from said cover toward the bottom, an air passage pathway being formed between said first and second collars, said box-like body being designed to be arranged in the functional configuration so that its bottom is substantially vertical.
REFERENCES:
patent: 3308317 (1967-03-01), Allenbaugh
patent: 4544166 (1985-10-01), Karasawa
patent: 26 17 860 (1977-11-01), None
patent: 43 30 648 (1995-03-01), None
patent: 2 750 810 (1998-01-01), None
Akerman & Senterfitt
Askoll Holding S.r.l.
Mullins Burton
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