Volute for centrifugal pump

Abstract

A casing 10 of a pump has first and second casing elements 20, 30. Each of the casing elements has a mating face and these mating faces are sealingly joined. An interior of the first casing element defines a portion of a chamber 50 in which the impeller is mounted. A first interior portion of the second casing element defines the remaining portion of the impeller chamber, and a second interior portion defines a diffusion chamber 60 that is in fluid communication with the impeller chamber. Fluid entering the casing at a fluid inlet 34 passes into the impeller chamber, where velocity is imparted to the fluid. The velocity-enhanced fluid passes axially into the diffusion chamber, which has an expanding cross-sectional area along its length, to convert the velocity into pressure head, which is achieved increasing by at least one of: the radially-inward width and the axial height.

1 . A casing for housing an impeller, comprising:
 a first casing element, an interior thereof defining a portion of a chamber for the impeller, the impeller chamber portion proximate to a mating face of the first casing element; and   a second casing element, a first interior portion thereof defining the remaining portion of the impeller chamber, the remaining portion of the impeller chamber proximate to a mating face of the second casing element, and a second interior portion of the second casing element defining a diffusion chamber in fluid communication with the impeller chamber; and   means for sealingly mating the respective mating faces.   
   
   
       2 . The casing of  claim 1 , further comprising:
 an opening in the first casing element, co-axial with the impeller chamber, for connecting the impeller in the impeller chamber to a drive source external to the casing.   
   
   
       3 . The casing of  claim 2 , further comprising:
 a suction inlet in the second casing element, co-axial with the impeller chamber and communicating the impeller chamber with the exterior of the casing.   
   
   
       4 . The casing of  claim 1 , further comprising:
 a radially-extending disk in the second casing element, which separates the impeller chamber from the diffusion chamber.   
   
   
       5 . The casing of  claim 4 , wherein:
 the radially-extending disk has a diameter that is at least as large as a diameter of a base plate of the impeller.   
   
   
       6 . The casing of  claim 5 , further comprising:
 a gap between a circumference of the radially-extending disk and an interior wall of the second casing element that provides the fluid communication between the impeller chamber and the diffusion chamber.   
   
   
       7 . The casing of  claim 6 , wherein:
 the gap is annular.   
   
   
       8 . The casing of  claim 6 , wherein:
 the second casing element interior wall is located at a constant radial distance from an axis of the impeller.   
   
   
       9 . The casing of  claim 3 , further comprising:
 a tangential outlet in the second casing element, communicating the diffusion chamber with the exterior of the casing.   
   
   
       10 . The casing of  claim 9 , wherein:
 a cross-sectional flow area of the diffusion chamber decreases smoothly and monotonically in an angular direction away from the tangential outlet.   
   
   
       11 . The casing of  claim 9 , wherein:
 a fluid conduit through the casing is defined by the suction inlet, the impeller chamber, the diffusion chamber and the tangential outlet.   
   
   
       12 . The casing of  claim 1 , wherein:
 the sealingly mating means comprises a radially-extending circular flange at a circumferential edge of the mating face of each of the casing elements.   
   
   
       13 . The casing of  claim 12 , further comprising:
 a gasket interposed between the respective radially-extending circular flanges.   
   
   
       14 . A centrifugal pump, comprising:
 an impeller casing according to  claim 1 ; and   an impeller arranged for rotation in the impeller chamber.   
   
   
       15 . A casing for housing an impeller, the impeller having a base plate that defines a radial direction of the casing, with an axial direction of the casing normal to the radial direction, the casing comprising:
 a body in which the impeller is housed; and   a fluid conduit formed within the body, the fluid conduit comprising:
 a fluid inlet; 
 an impeller chamber, in which rotation of the impeller imparted velocity to fluid entering through the fluid inlet; 
 a diffusion chamber for volumetrically expanding fluid received from a fluid communication with the impeller chamber along a length of the diffusion chamber, the diffusion chamber characterized by a cross-sectional area that increases from a first end to a second end thereof, the increase in cross-sectional area provided by expansion of the diffusion chamber in at least one: of the radially inward direction and the axial direction; and 
 a fluid outlet, communicating the second end of the diffusion chamber with an exterior of the body.