Centrifugal pump for fluids containing solid materials, and gap seal

Abstract

The proposed rotary pump for transporting liquids containing solids is composed of a pump housing ( 1 ) and an impeller ( 2 ) disposed on a rotating driven shaft. The pump housing ( 1 ) encloses a flow space having an intake region ( 4 ) and having a pressure region ( 5 ) surrounding the periphery of the impeller ( 2 ), as well as also a back space ( 6 ) of the impeller. According to the invention, the gap ( 3 ) relative to the back space ( 6 ) of the impeller is completely sealed opposite the flow space relative to the transported liquid with the solids contained therein, wherein, however, there is provided a connection of the back space ( 6 ) of the impeller to the pressure region ( 5 ), by which its aeration and venting are made possible. Essential elements of an arrangement for sealing the gap ( 3 ) are: a sliding surface ( 10 ) formed on the impeller ( 2 ), an at least partially elastic sealing element ( 9 ) sliding along by its end ( 11 ) on the sliding surface ( 10 ), as well as means ( 15, 15′, 16, 16′, 17, 17′, 18, 18′ ) for the aerating and venting of the back space ( 6 ) of the impeller, wherein the sealing element ( 9 ) is fixed in place on a pressure cap ( 12 ) closing the pump housing ( 1 ) on the side facing away from the intake region ( 4 ).

1 . A rotary pump for transporting liquids containing solids, with a pump housing having a media inlet opening and a media outlet opening for the liquid to be transported in each case, and an impeller disposed on a rotating driven shaft in the pump housing, wherein the pump housing encloses a flow space with an intake region on a front side of the impeller facing the media inlet opening and with a pressure region that surrounds the periphery of the impeller, as well as a back space of the impeller, which is formed on the side of the impeller facing away from the media inlet opening, is hereby characterized in that a structurally-imposed gap relative to the back space of the impeller is completely sealed opposite the flow space for the transported liquid with the solids contained therein by means of a sealing element that slides along by an elastic end on a low-wear sliding surface of the impeller, wherein, however, an aerating and venting of the back space of the impeller is given via a connection provided therefor to the pressure region of the flow space. 
     
     
         2 . The rotary pump according to  claim 1 , further characterized in that it involves a wastewater pump. 
     
     
         3 . An arrangement for gap sealing in a rotary pump for transporting liquids containing solids, having an impeller taken up by a pump housing, with an at least partially elastic sealing element and with a sliding surface, which is formed on the impeller and on which an elastic end of the sealing element slides along during the operation of the rotary pump, is hereby characterized in that the sealing element is fixed in place on a pressure cap closing the pump housing on the side facing away from an intake region of the rotary pump and the sliding surface is formed on the impeller in the region of a gap to a back space of the impeller on the side of the impeller facing away from the intake region and that the arrangement comprises means for aerating and venting the back space of the impeller. 
     
     
         4 . The arrangement according to  claim 3 , further characterized in that at least the end of the sealing element sliding along on the sliding surface of the impeller is composed of an elastomer. 
     
     
         5 . The arrangement according to  claim 4 , further characterized in that the regions of the sealing element composed of an elastomer are interlaced by a fabric, at least in sections. 
     
     
         6 . The arrangement according to  claim 3 , further characterized in that the sealing element is fixed in place on the pressure cap by means of an adhesive connection or by vulcanization. 
     
     
         7 . The arrangement according to  claim 4 , wherein the entire sealing element is composed of an elastomer, characterized in that the sealing element is fixed in place on the pressure cap in a force-fitting manner or in a force-fitting and form-fitting manner. 
     
     
         8 . The arrangement according to  claim 7 , further characterized in that the sealing element is formed as an elastomeric sealing ring, which slides along on the sliding surface of the impeller by a first axial segment forming the elastic end and is pulled onto a section or shoulder of the pressure cap projecting into the back space of the impeller by a second axial section. 
     
     
         9 . The arrangement according to  claim 8 , further characterized in that the axial section is conically tapered relative to its diameter. 
     
     
         10 . The arrangement according to  claim 8 , further characterized in that in the pressure cap relative to its periphery, there are formed on each of at least two positions a first borehole extending into the material of the pressure cap behind the axial section of the sealing element in the radial direction and a second borehole extending in the axial direction from the backspace of the impeller up to the first borehole, for the aerating and venting of the back space of the impeller. 
     
     
         11 . The arrangement according to  claim 8 , further characterized in that in the sealing element, which is formed as a sealing ring, relative to its periphery, there is formed on each of at least two positions a passage extending in the radial direction into the back space of the impeller, for the aerating and venting of the back space of the impeller. 
     
     
         12 . The arrangement according to  claim 7 , wherein an axial end of the pressure cap projecting into the back space of the impeller has a larger diameter than the impeller, further characterized in that the sealing element is formed as a sealing collar gripping a shoulder of the pressure cap from behind, this sealing collar having a section extending between pressure cap and impeller in the radial direction, for the equilibration of the different diameters. 
     
     
         13 . The arrangement according to  claim 12 , further characterized in that in the section of the sealing element formed as a sealing collar, extending in the radial direction relative to its periphery, there are formed on each of at least two positions a passage projecting through the section in question in the axial direction and a support composed of the material of the sealing collar and projecting in the axial direction onto the side facing the pressure cap, for the aerating and venting of the back space of the impeller. 
     
     
         14 . The arrangement according to  claim 7 , further characterized in that the sealing element for the additional fixation on the pressure cap is joined adhesively therewith via vulcanization. 
     
     
         15 . The arrangement according to  claim 3 , further characterized in that the low-wear sliding surface is provided by a wear-resistant coating of the impeller. 
     
     
         16 . The arrangement according to  claim 3 , further characterized in that for the formation of the sliding surface, a liner is pressed onto the periphery or onto a machined shoulder of the impeller on the side facing the back space of the impeller, the sliding surface being formed on the radial outer surface of the liner composed of a low-wear material. 
     
     
         17 . The arrangement according to  claim 3 , wherein an axial end of the pressure cap projecting into the back space of the impeller has a greater diameter than the impeller, characterized in that for the formation of the sliding surface, a liner is pressed onto the periphery or onto a machined shoulder of the impeller on the side facing the back space of the impeller, wherein the sliding surface on the radial outer surface of a bearing race connected to the liner, projecting opposite thereto in the radial direction is formed of a low-wear material.