Pumps – Motor driven – With means to prevent heat transfer between pump and motor
Patent
1997-11-14
1999-06-15
Freay, Charles G.
Pumps
Motor driven
With means to prevent heat transfer between pump and motor
4174238, F04B 3906
Patent
active
059115653
DESCRIPTION:
BRIEF SUMMARY
CROSS-REFERENCE TO RELATED APPLICATIONS
This is the national stage of International Application No. PCT/EP96/00921 filed Mar. 5, 1996.
BACKGROUND OF THE INVENTION
The service life of the seal and of the rolling bearing of a pump shaft depends on the temperature. With an increasing temperature of the medium to be delivered by the pump--for example hot oil at 350.degree. C.--increasing requirements are placed on the temperature resistance or cooling of the seal and bearing housing. It is known (EP-A 535365) to arrange the seal housing of a centrifugal pump for delivering hot media at an axial distance from the pump housing, to arrange the drive-side shaft bearing at a distance from the bearing housing and to provide a fan on the shaft in the spacing between the shaft bearing and the seal housing, which fan sucks in ambient air and drives it in the direction towards the pump axially over the surface of the seal housing in order to cool the latter. This flow direction is plausible because the flow leaving the fan wheel has a higher speed than the intake flow, and because the air flow heated by the seal housing and the pump surface is conducted away from the drive motor which is sensitive to temperature and is arranged on the other side of the bearing housing. Since it is undesirable also to cool the pump by means of the air flow, in the known pump a thermal insulation device is provided on the side of the pump facing the air flow.
In another known pump (GB-B-998313), air is fed to a heat exchanger by the fan located between the seal and the drive motor, which heat exchanger provides the seal with cooled liquid. The air sucked in by the fan brushes along the end face of the seal housing facing the motor and cools the said seal housing. Since the cooling effect is based primarily on the cooling liquid fed directly to the seal, no devices are provided which ensure intensive air cooling of the seal housing.
SUMMARY OF THE INVENTION
A motor pump arrangement is known (DE-A 27 50 967), in which a fan wheel is arranged between the motor and the pump, which fan wheel serves to drive ambient air as a cooling medium through a heat exchanger which is likewise arranged between the motor and the pump. Since the pump is not hot and there are no housing parts to be cooled between the motor and the pump, the type of air conduction to the fan wheel has no thermal significance. In particular, the fact that the air can impinge radially on the coupling provided between the pump and the motor has no functional relevance to the invention at all. The present invention overcomes the disadvantages of the above-described prior art pumps with respect to the cooling of the seal housing.
Accordingly, the invention is characterized in that the delivery direction of the fan wheel runs from the pump to the bearing housing, and in that the air inlet cross-sections formed by the guard plate are arranged in the axial region of the seal housing and/or on the pump side thereof in such a way that the air impinges with a radial direction component on the seal housing and/or the connection between the seal housing and the pump housing and is deflected on the seal housing towards the fan wheel.
It is surprising that an intensification of the cooling effect is thus achieved. On the one hand, this is attributed to the fact that the effect of the fan wheel is improved because its intake conditions are improved owing to the air flowing into it axially. On the other hand, the improvement is based on the fact that the deflection of the air flow taking place directly on the surface of the seal housing or just ahead of it improves the thermal transfer on the surface of the seal housing. In this case, the thermal insulation device located between the pump housing and the seal housing ensures that the air flow sucked in is not heated unnecessarily before it reaches the seal housing.
The thermal insulation device can simply be formed by a metal washer which is fitted in front of the pump housing and encloses with the latter a thermally insulating air spac
REFERENCES:
patent: 2202424 (1940-05-01), Hough
patent: 2484275 (1949-10-01), Eastman
patent: 3738781 (1973-06-01), Hagemann et al.
patent: 4172697 (1979-10-01), Schoen
patent: 4632643 (1986-12-01), Nielsen
patent: 5624245 (1997-04-01), DeClerck et al.
Kuhrt Hauke
Mann Ralf
Freay Charles G.
Sterling Fluid Systems (Germany) GmbH
Tyler Cheryl J.
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