Patent Publication Number: US-2010111687-A1

Title: Centrifugal Pump Comprising a Spiral Housing

Description:
PRIORITY CLAIM 
     This is a U.S. national stage of application No. PCT/EP2008/051570, filed on Feb. 8, 2008, which claims Priority to the German Application No. 10 2007 010 050.9, filed: Mar. 1, 2007 the contents of both being incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a centrifugal pump having a spiral housing. The invention further relates to the use of the centrifugal pump. 
     2. Prior Art 
     Centrifugal pumps having spiral housings are known. DE 103 47 302 A1 describes a two-part spiral housing for a centrifugal pump, which is of optimized design from the point of view of fluid mechanics. Such centrifugal pumps are generally driven by an electric motor, the stator of the electric motor being arranged in a dry chamber and the rotor in a wet chamber. The rotor therefore turns in the wet chamber, which is the medium to be pumped. The dry chamber and the wet chamber are divided by a separately arranged can. A disadvantage being that it is necessary to arrange sealing elements between the one part of the spiral housing and the can avoid liquid or vapor from the wet chamber getting into the dry chamber. Over prolonged operating times, as the seal gradually becomes porous, or when subjected to vibrations acting on the centrifugal pump, it is often not possible to avoid liquid or vapor passing from the wet chamber into the dry chamber. This results, in damage to electronic components, which in addition to the stator are also arranged in the dry chamber. 
     SUMMARY OF THE INVENTION 
     An object of the invention, is to create a centrifugal pump having a spiral housing, in which liquid or vapor from the wet chamber enclosing the rotor is prevented from entering the dry chamber. 
     The object of the invention is achieved by a centrifugal pump having a spiral housing, which comprises a first housing part and a second housing part, in which the central area of the second housing part is of a continuous cup-shaped design to accommodate the rotor situated in the wet chamber N, and a bearing for the rotatable mounting of the rotor is formed in the cup-shaped base part, a stator being arranged in the dry chamber T externally surrounding the second housing part in the area of the rotor. The central area of the second housing part is of a continuous cup-shaped design, which means that it forms a virtually cylindrical part with terminating base. The cup-shaped design defines the wet chamber N, which accommodates the rotor. In the cup-shaped base part the second housing part forms a bearing for the rotatable mounting of the rotor, the cup-shaped base part either itself serving as bearing or accommodating a bearing for the rotor. 
     Due to the continuous cup-shaped configuration of the second housing part, it is possible to completely prevent liquid from the wet chamber N getting into the dry chamber T. There is advantageously no need to divide the wet chamber N from the dry chamber T through sealing elements by way of a separate can. A continuous separation of the dry chamber T from the wet chamber N is ensured even over prolonged operating times. The arrangement of a separate can is advantageously dispensed with altogether. 
     In a preferred embodiment of the invention the outer area of the second housing part has an outline of curved longitudinal section perpendicular to the direction of flow of the medium flowing in from the inlet E. The precise curved profile is engineered to optimize the fluid mechanics of the spiral housing. This is an advantageous way of adjusting the flow conditions in the spiral housing to an optimum setting, so that the overall space required for the centrifugal pump is reduced. The invention further relates to the use of the centrifugal pump as a coolant centrifugal pump in a motor vehicle. Coolant centrifugal pumps in motor vehicles have to function over a prolonged time, there being a need to avoid damaging the electronic components in the dry chamber T. The use of the centrifugal pump as a coolant centrifugal pump in a motor vehicle is therefore particularly advantageous. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be explained in more detail below by way of example and with reference to the drawings. 
         FIG. 1  is a perspective view in longitudinal section through the centrifugal pump; 
         FIG. 2  is a perspective view in longitudinal section through the centrifugal pump in the form of an exploded diagram; and 
         FIG. 3  is a perspective view in longitudinal section through a centrifugal pump according to the state of the art. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  is a centrifugal pump in longitudinal section. It comprises a spiral housing, which comprises a first housing part  1  and a second housing part  2 . A central area of the second housing part  2  is of a continuous cup-shaped design to accommodate the rotor  3  situated in a wet chamber N. In the cup-shaped base part  2 ′ the second housing part  2  has a bearing  3 ′ for the rotatable mounting of the rotor  3 . A stator  4  is arranged in a dry chamber T externally surrounding the second housing part  2  in the area of the rotor  3 . The dry chamber T is sealed from the surroundings by a housing  5 . The outer area of the second housing part  2  has an outline  2 * of curved longitudinal section perpendicular to the direction of flow of the medium flowing in from the inlet E. The medium flowing in is represented by a bold arrow. The curved outline  2 * serves to optimize the flow conditions inside the spiral housing. Any ingress of liquid or vapor from the wet chamber N into the dry chamber T is prevented even without the arrangement of sealing elements, so that electronic components (not shown) and the stator  4  in the dry chamber are protected against damage by liquid or vapor. 
       FIG. 2  is the centrifugal pump of  FIG. 1  in longitudinal section in the form of an exploded diagram. The central area of the second housing part  2  is of a continuous cup-shaped design configured to accommodate the rotor  3 . The wet chamber N (not shown) defined by this central area is therefore completely screened off from the dry chamber T (not shown), in which the stator  4  is situated. 
       FIG. 3  shows a longitudinal section through a centrifugal pump according to the state of the art. The centrifugal pump according to the state of the art has a spiral housing, which comprises a first housing part  1   b  and a second housing part  2   b.  Liquid medium to be pumped, represented by the bold arrow, passes through the inlet Eb into the wet chamber Nb, in which the rotor  3   b  is rotatably mounted. A stator  4   b  in the dry chamber Tb is externally arranged in the area of the rotor  3   b.  The dry chamber Tb is here closed off from the surroundings by a housing  5   b.  In the state of the art the wet chamber Nb is separated from the dry chamber Tb by the arrangement of a can  6   b,  it being possible under certain circumstances for liquid to get into the dry chamber Tb from the wet chamber Nb owing to a disadvantageous arrangement of a sealing ring  7   b,  which has to be arranged between the can  6   b  and the second housing part  2   b.  Should the centrifugal pump be subjected to vibrations, for example, it is possible for liquid or vapors to pass from the wet chamber Nb via the sealing ring  7   b  into the dry chamber Tb, which is illustrated by the dashed lines. In this way the stator  4   b  or other electronic components (not shown), situated in the dry chamber Tb, may be damaged, something which is prevented by the centrifugal pump according to the invention. 
     Thus, while there have shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.