Patent ID: 9334874
Filing Date: 2016-05-10
CPC Classification: B01F,F04D,F05D

Claim Text:
1. A blade connectable to a central hub of an axial flow impeller, the blade being formed from substantially plate-type material and having a leading edge, a trailing edge, a tip, a root attachable to the central hub of the impeller, a first fold extending along the blade in a straight first direction and dividing the blade into a first profile portion located adjacent to the leading edge and a second profile portion, the first and the second profile portions meeting at the first fold such that the first profile portion is angled at a first angle (α a second fold extending along the blade in a straight second direction which is different from said first direction and located apart from the first fold and dividing the blade further into a third profile portion located adjacent to the trailing edge, said second and third profile portions meeting at said second fold such that the third profile portion is angled at a second angle (α and, in plan view, the blade has the general form of an enveloping rectangle (R×W said rectangle having a length R which is the lengthwise dimension from the axis of rotation of the impeller to the tip of the blade, and a width W a first cut-out which is adjacent the root and a first inner corner of the rectangle at the side of the leading edge, the first cut-out having a form of a right triangle with the lengthwise cathetus having a dimension A=0.2R, a widthwise cathetus having a dimension B=0.2W a second cut-out which is adjacent to the root and a second inner corner of the rectangle at the side of the trailing edge, the second cut-out having a form of a right triangle with the lengthwise cathetus having a dimension C=0.2R, a widthwise cathetus having a dimension D=0.2W a third cut-out which is adjacent to the tip and a first outer corner of the rectangle at the side of the leading edge, the third cut-out having a form of a right triangle with the lengthwise cathetus having a dimension E=0.5R, a widthwise cathetus having a dimension F=(0.1 to 0.2)R and a hypotenuse which forms a third cut-out edge of the blade extending from the leading edge to the tip, the third cut-out edge connecting to the tip with a rounding having a radius of curvature G=0.2W a fourth cut-out which is adjacent to the tip and a second outer corner of the rectangle at the side of the trailing edge, the fourth cut-out having a form of a right triangle with the lengthwise cathetus having a dimension H=0.25R, a widthwise cathetus having a dimension I=0.1R and a hypotenuse which forms a fourth cutout edge of the blade extending from the trailing edge to the tip, the fourth cut-out edge connecting to the tip with a rounding having a radius of curvature G=0.2W that the first fold intersects the lengthwise side of the enveloping rectangle at the meeting point of the first cut-out edge and the leading edge at the distance A=0.2R from the first inner corner, and the first fold intersects the widthwise side of the enveloping rectangle adjacent to the tip at the distance J=0.4R from the third corner; that the second fold intersects the widthwise side of the enveloping rectangle adjacent to the root at a widthwise distance K=0.1W and that the first angle (α