Rotary kinetic fluid motors or pumps – Working fluid passage or distributing means associated with... – Casing having tangential inlet or outlet
Patent
1992-03-04
1993-07-20
Kwon, John T.
Rotary kinetic fluid motors or pumps
Working fluid passage or distributing means associated with...
Casing having tangential inlet or outlet
415914, F04D 100
Patent
active
052288315
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a centrifugal pump.
Sheet metal centrifugal pump casings have very good strength and, depending upon the material used, high resistance to the most diverse pumped media. A drawback of these casings produced from sheet metal is their low resistance to abrasive constituents in the pumped medium. In contrast to a substantially thicker cast casing, the thin-walled sheet metal casing is more readily damaged under the influence of abrasive constituents.
A sheet metal casing is known from the German Offenlegungsschrift 35 17 498. The outer periphery of the casing has an opening and a discharge branch is fitted in the opening. The so-called spine formed by the discharge branch, which facilitates discharge of the pumped medium from the annular chamber into the discharge branch, can be flush with the annular chamber or can project into the annular chamber. The spine is very susceptible to wear during the pumping of media with abrasive constituents.
For a pump casing of the above type, it is accordingly an object of the invention to develop a solution which guarantees a life equivalent to that of a cast casing during the pumping of media containing abrasive constituents.
This object is achieved by the provision of a pump which comprises a casing having a peripheral wall which surrounds a chamber for a rotor serving a convey a fluid circumferentially of the wall in a predetermined direction. The wall has an outlet opening for the fluid, and the upstream and downstream sides of the opening extend transversely of the direction of fluid flow in the casing. The opening is flanked by at least two projections or shielding elements which extend into the chamber transversely of the direction of fluid flow and are disposed at the upstream and downstream sides of the opening.
The outlet from the annular chamber, where a deflection of the flow into the discharge branch takes place, has been found to be especially susceptible to wear. By means of the solution according to the invention, with which the efficiency remains essentially the same, the flow is deflected to a degree, in the region of the outlet opening, towards the center of the casing to subsequently advance into the discharge branch without damage to the outlet opening. The projection mounted at the trailing edge of the outlet opening acts to a certain extent to conduct the flow into the discharge branch but, at the same time, also acts as a wear part and protects the thin casing wall from damage.
An embodiment of the invention provides for the length of the projections to equal the width of the annular chamber. Depending upon the shape of the outlet opening employed and the width relationships of the annular chamber and the outlet opening, the projections can extend over the entire length or a plurality of parts can be distributed in a staggered arrangement. The abrasive constituents are removed from the marginal zones of the outlet opening by the projections and thereafter freely enter the discharge branch.
For projections which are embossed in the sheet metal casing, linings applied to the projections externally of the casing have the effect that, upon wear of the projections, the casing does not become leaky at this location.
The ratio between the height of the projections and the diameter of the annular chamber preferably between 0.01 and 0.04. Such ratio ensures that a good protective effect is achieved with hardly any, or with only a tolerable, loss in efficiency.
The projection mounted at the trailing edge of the outlet opening can extend into the discharge branch. At this location, which is also referred to as a spine, the projection acts as a wear shield against directly impinging abrasive particles.
According to another embodiment, a plurality of projections are distributed over the periphery of the annular chamber. Although this measure guarantees very good protection for the annular chamber, distinct losses in efficiency occur here.
FIG. 1 shows a first embodiment of the invention.
FIG. 2 shows a second embodiment of the invention.
REFERENCES:
patent: 893113 (1908-07-01), Traylor
patent: 1914919 (1933-06-01), Heermans
patent: 3647314 (1972-03-01), Laessig
patent: 4789301 (1988-12-01), Osborne et al.
patent: 4844693 (1989-07-01), Grzina
Kontler Peter K.
KSB Aktiengesellschaft
Kwon John T.
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