Apparatus for impeller sealing in centrifugal pumps

Abstract

The invention relates to a device for impeller sealing in centrifugal pumps for fluid media, by means of which the gap between pump housing ( 1 ) and at least one impeller ( 2 ) is completely sealed against a transport of material from the pressure side ( 3 ) of impeller ( 2 ) to the suction side ( 4 ) thereof. According to the invention, a sealing ring comprising a rigid pressure ring ( 7 ) as well as an annular elastic sealing lip ( 8 ) joined with pressure ring ( 7 ) is disposed in pump housing ( 1 ) between pressure side ( 3 ) and suction side ( 4 ), whereby, when the centrifugal pump is in operation, sealing lip ( 8 ) is applied in sliding manner over the entire periphery of impeller ( 2 ) on a sliding surface ( 6 ) formed on impeller ( 2 ) in the region of impeller intake ( 5 ). For this purpose, the sealing ring is positioned in pump housing ( 1 ) by means of an adjusting member ( 9 ) and its sealing lip ( 8 ) inclined against said sliding surface ( 6 ) is pre-stressed.

1 . A device for impeller sealing in centrifugal pumps for fluid media, by means of which the axial or radial gap which is formed between the pump housing and at least one motor shaft-driven impeller of the centrifugal pump and which makes possible the rotational movement of impeller in pump housing is sealed against a transport of material from the pressure side of the at least one impeller to the suction side thereof at the impeller intake is hereby characterized in that a sealing ring is disposed in pump housing between the pressure side and the suction side of the respective impeller, this sealing ring being composed of a rigid pressure ring and an annular elastic sealing lip joined with pressure ring, this lip being joined to pressure ring in the region of its inner diameter and being inclined against a sliding surface formed on impeller at the peripheral contour in the region of the impeller intake in a region projected on by pressure ring or/and projecting over the diameter thereof, and that an adjusting member mounted in pump housing acts on the sealing ring, by means of which the sealing ring is positioned relative to sealing surface and its sealing lip is pre-stressed in region in such a way that sealing lip is applied to sliding surface by a radially outer end of its region, when the centrifugal pump is operating, due to the pressure difference existing between pressure side and suction side, and completely seals the axial gap or the radial gap, whereby, due to the deformability of region of sealing lip and the pre-stressing produced in sealing lip by means of adjusting member, a permanent, self-adjusting seal as well as a seal that equilibrates the radial and axial oscillations occurring during operation of the pump is provided. 
     
     
         2 . The device according to  claim 1 , further characterized in that sliding surface is part of a rigid wear ring attached to the peripheral contour of impeller in the region of impeller intake. 
     
     
         3 . The device according to  claim 1 , further characterized in that sealing lip comprises an elastomer and is joined to pressure ring by vulcanization, whereby pressure ring comprises metal. 
     
     
         4 . The device according to  claim 3 , further characterized in that a reinforcing material is embedded in the elastomer of sealing lip. 
     
     
         5 . The device according to  claim 4 , further characterized in that a metal wire mesh is embedded in the elastomer of sealing lip. 
     
     
         6 . The device according to  claim 3 , further characterized in that a metal washer is vulcanized in sealing lip. 
     
     
         7 . The device according to  claim 1 , further characterized in that the thickness of annular sealing lip decreases in the direction of its outer periphery. 
     
     
         8 . The device according to  claim 1 , further characterized in that the adjusting member is formed as a collar directly acting on the sealing ring, the position of the collar being adjustable in pump housing in the axial direction by means of two or more adjusting screws arranged approximately equally distributed relative to the periphery of collar, each of these screws being engaged with a thread of pump housing and pressing on collar. 
     
     
         9 . The device according to  claim 8 , further characterized in that the threads for adjusting screws are formed in threaded bores, which are guided through pump housing in the axial direction. 
     
     
         10 . The device according to  claim 8 , further characterized in that an additional housing ring which is applied to collar on the side opposite to the sealing ring is inserted into pump housing and each of the threads for adjusting screws is formed in part by circular segment-shaped recesses disposed on the outer periphery of housing ring and in part disposed in annular recesses of pump housing corresponding to recesses of pump housing and enclosing together with these a full circle in each case, wherein housing ring is fixed in pump housing by adjusting screws engaged with the threads. 
     
     
         11 . The device according to  claim 1 , further characterized in that the adjusting member is formed as a collar with an outer thread, this collar acting directly on sealing ring, and the position of this collar is adjustable in pump housing in the axial direction by turning collar in an inner thread formed on an inner surface of pump housing. 
     
     
         12 . The device according to  claim 8 , further characterized in that collar can be fixed in the axial position adjusted for it by means of set screws. 
     
     
         13 . The device according to  claim 8 , further characterized in that the respective elements thereof are components of a kit for retrofitting centrifugal pumps which have not previously been equipped with a gap seal, and a drilling template or hole gauge for the correct positional arrangement of threaded bores to be formed is also included in the kit. 
     
     
         14 . The device according to  claim 11 , further characterized in that collar can be fixed in the axial position adjusted for it by means of set screws.