Pumps – Motor driven – Electric or magnetic motor
Patent
1996-10-15
2000-02-01
Mohanty, Bibhu
Pumps
Motor driven
Electric or magnetic motor
417368, F04B 1700
Patent
active
060195819
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a single flow friction vacuum pump with a housing in which an inlet, the active pumping surfaces and a drive motor are arranged axially behind each other.
A friction vacuum pump of this kind is known from DE-U-80 27 697. During operation of pumps of this kind a cooling arrangement is generally necessary. Water cooling is on the one hand very effective, but on the other hand makes operation of the pump dependant on the presence of a cooling water supply connection. Moreover, design complexity required for the water cooling arrangement at the pump itself is relatively high. Moreover, it is known to employ a separate air cooling unit with a fan which is installable to the outside of the pump housing. On the one hand, such a cooling unit will only cool the outer surface of the pump housing, i.e. its cooling effect is restricted. On the other hand, additional installation work is necessary when cooling is required.
SUMMARY OF THE INVENTION
It is the task of the present invention to equip a friction vacuum pump of the aforementioned kind with an improved air cooling arrangement which is easier to handle.
According to the present invention this task is solved by equipping its housing walls with air intake and air discharge openings and so that a fan is integrated in its housing.
In a so designed pump, installation work is no longer necessary when cooling is required. Since the fan is situated in the housing, preferably at the side next to the drive motor, the cooling effect is particularly good. The cooled surface of the pump is more effective than otherwise possible through outer (orientation dependant) cooling fins. Moreover, the surface available for the transfer of heat is significantly larger compared to an outside surface with fins, since also the inside surface of the housing contributes to the cooling effect. The additional fan which may be switched on as required, supplies the air directly to those locations which generate heat and are thus at the highest temperature level. Thus the "cooling chain" (thermal transitions, thermally conducting paths, thermal capacities, thermal passages etc.) through which the heat has to be transported according to the state-of-the-art, becomes shorter at a steadily reducing temperature level, so that the additional fan may be of a smaller rating and may thus even be integrated into the pump.
Preferably the built-in fan is operated in such a manner that it is controlled by a temperature sensor. The pump is thus at all times protected against an undesirable temperature increase.
If inlet openings for the cold air supply, and discharge openings to discharge the warm air are provided in the housing walls of the pump, it is then possible to attain a chimney effect by skillfully admitting the flow, so that the flow passes the wall from the inside to the outside thereby creating a natural force-ventilation arrangement. This cools in addition and more effectively compared to the free convection which is present in any case at the outside of the wall. The air passage is so selected that the cooling effect is independent of the pump's orientation. Owing to the cone-shaped housing design, the air flow is not obstructed by neighbouring parts even if the pump is installed in a system. Moreover, there is sufficient space in the area of the drive to accommodate all necessary components, the fan among others, in the housing while keeping the axial dimension short.
Further advantages and details of the present invention shall be explained based on the design examples presented in drawing FIGS. 1 to 6.
BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the invention, reference shall be made to the following detailed description of the invention which is to be read in association with the accompanying drawings, wherein:
FIG. 1 is an elevational view in section showing a pump embodying the teachings of the present invention;
FIG. 2 is a side elevation of the pump further indicating air flow through the pump;
FIG. 3 is a
REFERENCES:
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patent: 4742257 (1988-05-01), Carpenter
patent: 4908538 (1990-03-01), Gerberth, Jr.
patent: 4992687 (1991-02-01), Nel
patent: 5166566 (1992-11-01), Bernhardt et al.
patent: 5662456 (1997-09-01), Englander
Englander Heinrich
von Schulz-Hausmann Friedrich
Walter Wilhelm
Leybold Aktiengesellschaft
Mohanty Bibhu
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