Patent ID: 9605678
Date: 2017-03-28
CPC Classifications: F04D

Claim:
1. A free-flow pump comprising an impeller spaced from an inlet in such a manner that a free passage for solids contained in pumped liquid results between the inlet and an impeller exit, the impeller comprising: an impeller base comprising a front side of a hub body projecting at a center of the impeller and a disk surface located deeper seen in the direction of a rotation axis of the impeller than the front side of the hub body and reaching to an outer circumference of the impeller with its maximum depth; the disk surface comprising vanes comprising open vane front sides adjoining the hub body at their inner end and extending from the inner end to an outer circumference of the impeller, wherein within an inner third of a disk surface radius, the disk surface is located at most at a first predetermined depth with respect to the inner end of the vane front sides seen in the direction of the rotation axis of the impeller, the first predetermined depth being a depth at most one sixth of a height difference (H) between the inner end of the vane front sides and a maximum depth of the disk surface, wherein within an inner half of the disk surface radius, the disk surface is located at most at a second predetermined depth with respect to the inner end of the vane front sides seen in the direction of the rotation axis of the impeller, the second predetermined depth being a depth at most two thirds of the height difference between the inner end of the vane front sides and the maximum depth of the disk surface, wherein the disk surface comprises a surface portion continuously declining toward the outer circumference of the impeller, and wherein said surface portion extends over one half or more of the radius of the impeller.