Centrifugal pump for processing liquids containing abrasive constituents, more particularly, a sand pump or a waste-water pumper

Claim 2

A centrifugal pump for processing liquids containing abrasive constituents, more particularly, a sand pump or a waste-water pump comprising a housing having a suction opening and a delivery opening and an impeller rotatably arranged in said housing, said housing including an inner sleeve on either side of said impeller and said impeller having a pair of outer sleeves on one side thereof embracing one of said inner sleeves and a further outer sleeve surrounding the other of said inner sleeves, the radially outermost sleeves on opposite sides of said impeller defining sealing slots between said inner and radially outermost sleeves, each outermost sleeve having an annular chamber formed therein and means for rotating the liquid in the chamber, and each outermost sleeve having radial, outwardly, directed ducts communicating with the annular chamber.

Claim 3

A centrifugal pump as claimed in claim 1, characterised in that the end face of each outermost sleeve is provided with radial ridges.

Claim 4

A centrifugal pump as claimed in claim 2 characterised in that the ridges have inclined contact faces.

Claim 5

A centrifugal pump as defined in claim 1 including a second set of radial ducts communicating with each sealing slot and opening out at a larger diameter than the first set of ducts.

Claim 6

A centrifugal pump as claimed in claim 4, characterised in that the end of the second set of ducts is located at the end of the main impeller.

Claim 7

In a centrifugal pump assembly, the combination of: a housing having an inlet opening and an annular delivery chamber; an impeller having an inlet eye aligned with said inlet opening and a peripheral portion discharging to said delivery chamber, said impeller and said housing defining an intermediate chamber therebetween leading to said delivery chamber; and sealing means formed between said housing and said impeller between said inlet opening and said delivery chamber for bleeding liquid from said intermediate chamber to said inlet opening, said sealing means including opposed surface portions of said impeller and said housing defining a sealing slot having an outer end communicating with said intermediate chamber and an inner end communicating with said inlet opening, an annular chamber defined between said surface portions adjacent said outer end of the sealing slot, and duct means in said impeller leading from said annular chamber to said intermediate chamber for redirecting sediment entering said outer end of the sealing slot back into said intermediate chamber, and wherein said surface portions are defined by an outer sleeve on said impeller and an inner sleeve on said housing, said annular chamber being formed in said outer sleeve.

Claim 8

In a centrifugal pump assembly, the combination of: a housing having an inlet opening and an annular delivery chamber; an impeller having an inlet eye aligned with said inlet opening and a peripheral portion discharging to said delivery chamber, said impeller and said housing defining an intermediate chamber therebetween leading to said delivery chamber; and sealing means formed between said housing and said impeller between said inlet opening and said delivery chamber for bleeding liquid from said intermediate chamber to said inlet opening, said sealing means including opposed surface portions of said impeller and said housing defining a sealing slot having an outer end communicating with said intermediate chamber and an inner end communicating with said inlet opening, an annular chamber defined between said surface portions adjacent said outer end of the sealing slot, and duct means in said impeller leading from said annular chamber to said intermediate chamber for redirecting sediment entering said outer end of the sealing slot back into said intermediate chamber, and wherein said surface portions are defined by an outer sleeve on said impeller and an inner sleeve on said housing, said annular chamber being formed in said outer sleeve.

Claim 9

In a centrifugal pump assembly as defined in claim 6 including second duct means formed in said impeller and leading from the inner end of said sealing slot to said delivery chamber.

Claim 10

In a pump assembly as defined in claim 7 wherein the outer end of said outer sleeve is provided with radially extending teeth.