Rotary kinetic fluid motors or pumps – With separating means or guard for solid matter in working...
Patent
1991-05-07
1993-08-10
Kwon, John T.
Rotary kinetic fluid motors or pumps
With separating means or guard for solid matter in working...
415110, 241 97, F04D 2970
Patent
active
052343162
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a filtering device for a canned motor.
Various designs and various filter inserts for such filtering devices are known - e.g., from the British patent application 1 237 633. They are used mainly in canned motor pumps which function to convey contaminated fluids. The known filtering devices are mostly situated in the wall between the pressure chamber of the centrifugal pump and the rotor chamber of the canned motor. The filter insert, which consists of a porous material, a strainer or the like, tends to become clogged after a period of time which depends upon the type and quantity of the solid inclusions. This leads to interruption of the rinsing stream conducted through the rotor chamber so that the heat generated in the canned motor due to power losses is no longer adequately removed. As a result of this circumstance, continuous monitoring and frequent maintenance (replacement or cleaning of the filter insert) are necessary.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a filtering device for canned motors which, on the one hand, traps solid particles having a size such that the downstream gap is endangered and, on the other hand, is not imperiled by obstruction or clogging.
According to the invention, the object set forth is achieved in that a filtering gap bounded by sleeves of hard material is established between the housing and the rotor shaft and has a minimum width smaller than the minimum width of the downstream gap situated in the path of the rinsing stream inside the rotor chamber.
The principle of the invention is to allow small (harmless) particles to pass but to hold back larger inclusions until they have been ground to a safe size by the walls of the sleeves which define the filtering gap.
In accordance with the invention, the filtering gap can be constructed so as to enhance the grinding action of the filtering gap and increase the life of the sleeves forming the filtering gap.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described in greater detail with reference the drawings in which:
FIG. 1 is a section through a canned motor in the area of the filtering device; and
FIG. 2 is a section showing the motor of FIG. 1 coupled to a centrifugal pump.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1, a canned motor 11 has a rotor shaft 2 which is disposed in a housing 1. A ceramic sleeve 3 is inserted in the housing 1 and surrounds a sleeve 4 which has been pushed onto the rotor shaft 2 and likewise consists of ceramic. The confronting walls of the sleeves 3, 4 bound a filtering gap 5 located upstream of the rotor chamber 6 of the canned motor.
As shown in FIG. 2, a channel 7 in the housing 1 serves for the introduction of rinsing fluid from the pressure chamber 13 of a centrifugal pump 12. The channel 7 has an axially extending portion opening into a plurality of bores 8 which extend radially in the sleeve 3 and are distributed over the periphery thereof. The bores 8, in turn, open into an annular compartment 9 likewise defined by the sleeve 3. The annular compartment 9 narrows in the direction of the filtering gap 5 situated before the rotor chamber 6.
A passage 10 extending axially through the shaft 2 is provided for discharge of the rinsing fluid from the rotor chamber 6 as best seen in FIG. 2. The rinsing fluid arriving at the annular compartment 9 via the channel 7 and the bores 8 contains solid particles having a size greater than the width of the filtering gap 5. These particles are initially retained in the ring of fluid circulating upstream of the filtering gap 5. The current directed towards the rotor chamber again and again entrains a portion of the solid particles and conveys them to the inlet of the filtering gap 5. The particles are there gradually ground until they finally enter the filtering gap 5. Since they are here also subjected to a grinding action, their size at the end of the filtering gap is such that the following gap is no longer endangered. They are now carried
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patent: 4684318 (1987-08-01), Mulders
patent: 4812108 (1989-03-01), Kotera
Kontler Peter K.
KSB Aktiengesellschaft
Kwon John T.
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