Impeller and fluid pump

An impeller for a fluid pump, comprising:

• a hub having an opening adapted to receive a shaft that drives the impeller for rotation, a mid-hoop spaced radially from the hub and an outer hoop spaced radially from the mid-hoop;
• an inner array of vanes located radially outwardly of the hub and inwardly of the mid-hoop;
• and
• an outer array of vanes located between the mid-hoop and the outer hoop, both the inner array of vanes and the outer array of vanes configured to communicate with a single common fluid inlet and a single common fluid outlet,
• each vane in the inner array and the outer array has a leading face and a trailing face spaced circumferentially behind the leading face relative to the intended direction of rotation of the impeller, each vane has a root segment and a curved tip segment extending generally radially outwardly from the root segment, and the root segment extends between 10% and 50% of the radial length of each vane;
• the leading face of each vane is configured so that a line from a base of the root segment to an outer edge of the tip segment trails a line extending from the axis of rotation to the base of the root segment by a first angle of between 0° and −30°, relative to the direction of rotation of the impeller;
• the leading face of each vane is also configured so that a line extending from a radial mid-point of the vane to a radially outer edge of the vane is inclined relative to a line extending from the axis of rotation to the radial mid-point of the vane by a second angle of between −5° and −45° relative to the direction of rotation of the impeller;
• and
• the leading face of each vane is also configured so that a line extending from the base of the root segment to the outer end of the root segment is inclined relative to a line extending from the axis of rotation to the base of the root segment by a third angle of between −20° and 10° relative to the direction of rotation of the impeller;
• the leading face of each vane is curved from at least the radial mid-point to the tip of such leading face;
• and
• the leading face of each vane is also configured so that the tip segment is inclined rearwardly to a greater extent than the root segment relative to the direction of intended rotation of the impeller.

The method of making a fluid pump impeller, comprising:

• forming an impeller having a plurality of vanes in axially opposed faces and adapted to be rotated about an axis,
• forming a body that defines a radially outer sidewall of an impeller cavity in which the impeller rotates, the body having at least one generally axial face;
• positioning the impeller and the body so that one axial face of each may be machined at substantially the same time;
• and
• machining one axial face of the impeller and the body while so positioned and at substantially the same time to provide a similar axial thickness of the outer sidewall of the body and of the impeller.