Blower Fan Assembly

Abstract

A blower fan assembly comprising a scroll housing, a forward curved blower wheel, and a blower motor adapted to rotate the blower wheel about a blower wheel axis. The forward-curved blower wheel comprises a plurality of fan blades circumferentially spaced about the blower wheel axis. Each of the fan blades has a leading edge with a leading edge angle and a trailing edge with a trailing edge angle. The leading edge angle is at least 50° and not more than 80°. The trailing edge angle is at least 5.5° and not more than 18.5°. The outer radius is not more than 4 inches (101.6 mm).

What is claimed is: 
     
         1 . A blower fan assembly comprising:
 a scroll housing;   a forward curved blower wheel;   a blower motor adapted to rotate the blower wheel about a blower wheel axis;   the forward-curved blower wheel comprising a plurality of fan blades circumferentially spaced about the blower wheel axis, each of the fan blades having a leading edge and a trailing edge, the blower wheel having an inner radius, the inner radius of the blower wheel being the radial distance between the blower wheel axis and the leading edge of each fan blade, the blower wheel having an outer radius, the outer radius of the blower wheel being the radial distance between the blower wheel axis and the trailing edge of each fan blade, the leading edge of each fan blade having a leading edge angle, the leading edge angle being the angle between a first tangent line and a first reference line, the first tangent line being a line tangent to the camber line at the leading edge, the first reference line intersecting the leading edge and being perpendicular to a first radial line extending from the blower wheel axis to the leading edge, the first tangent line and the first reference line being in a plane perpendicular to the blower wheel axis, the trailing edge of each fan blade having a trailing edge angle, the trailing edge angle being the angle between a second tangent line and a second reference line, the second tangent line being tangent to the camber line at the trailing edge, the second reference line intersecting the trailing edge and being perpendicular to a second radial line extending from the blower wheel axis to the trailing edge, the second tangent line and the second reference line being in a plane perpendicular to the blower wheel axis, the leading edge angle being at least 50° and not more than 80° and the trailing edge angle being at least 5.5° and not more than 18.5°, the outer radius being not more than 4 inches (101.6 mm);   the blower wheel being within the scroll housing.   
     
     
         2 . The blower fan assembly of  claim 1 , wherein each fan blade has a stagger angle and a chord line, the stagger angle being the angle between the chord line and a radial line extending from the axis of rotation and intersecting the leading edge, the stagger angle being 30°±15°. 
     
     
         3 . The blower fan assembly of  claim 2  wherein the inner radius is at least 3.3 inches. 
     
     
         4 . The blower fan assembly of  claim 3  wherein the leading edge angle is 65°±5° and the trailing edge angle is 12°±3°. 
     
     
         5 . The blower fan assembly of  claim 4  wherein the plurality of fan blades comprises 40 blades. 
     
     
         6 . The blower fan assembly of  claim 4  wherein the scroll housing has a blower wall and opposite axial sides, the blower wall having a scroll profile as viewed in a plane perpendicular to the blower wheel axis, the blower wall extending axially from one of the axial sides to the other of the axial sides, the scroll profile of the blower wall extending circumferentially from a first scroll end to a second scroll end, the blower wall having a cut-off at the first scroll end, the scroll housing having a cut-off angle, the cut-off angle being an angle between a first radial scroll line extending from the blower wheel axis to the first scroll end and a second radial scroll line extending from the blower wheel axis to the second scroll end, the cut-off angle being 68°±10°. 
     
     
         7 . The blower fan assembly of  claim 6  wherein the blower wall has an exhaust wall portion and an exhaust angle, the exhaust wall portion extending generally straight from the second radial scroll line, the exhaust angle being the angle between the exhaust wall portion and an exhaust line, the exhaust line extending from the second scroll end and being perpendicular to the second radial scroll line, the exhaust angle being 5°±3°. 
     
     
         8 . The blower fan assembly of  claim 7  wherein the blower wall has an angle at cut-off, the angle at cut-off being the angle between a cut-off reference line and the cut-off, the cut-off reference line being perpendicular to the second radial scroll line and extending from the second radial scroll line through the cut-off, the angle at cut-off being 25°±5°. 
     
     
         9 . The blower fan assembly of  claim 8  wherein the blower wheel further comprises a blower wheel inlet and an internal cavity, the blower wheel inlet being axially aligned with the fan axis, the internal cavity being bounded by the blower wheel inlet and the leading edges of the fan blades. 
     
     
         10 . The blower fan assembly of  claim 9  wherein the blower wheel inlet comprises a first blower wheel inlet and the blower wheel further comprises a second blower wheel inlet, the internal cavity being further bounded by the second blower wheel inlet. 
     
     
         11 . The blower fan assembly of  claim 10  further comprising a center disc axially between and axially spaced from the first and second blower wheel inlets, and wherein the internal cavity comprises a first internal cavity portion and a second internal cavity portion, the first internal cavity portion being between the first blower wheel inlet and the center disc, the second internal cavity portion being between the second blower wheel inlet and the center disc. 
     
     
         12 . A blower fan assembly comprising:
 a scroll housing;   a forward curved blower wheel;   a blower motor adapted to rotate the blower wheel about a blower wheel axis;   the scroll housing having a blower wall and opposite axial sides, the blower wall having a scroll profile as viewed in a plane perpendicular to the blower wheel axis, the blower wall extending axially from one of the axial sides to the other of the axial sides, the scroll profile of the blower wall extending circumferentially from a first scroll end to a second scroll end, the blower wall having a cut-off at the first scroll end, the scroll housing having a cut-off angle, the cut-off angle being an angle between a first radial scroll line extending from the blower wheel axis to the first scroll end and a second radial scroll line extending from the blower wheel axis to the second scroll end, the cut-off angle being 68°±10°;   the blower wall having an exhaust wall portion extending generally straight from the second radial scroll line and an exhaust angle, the exhaust angle being the angle between the exhaust wall portion and an exhaust line, the exhaust line being perpendicular to the second radial scroll line and intersecting the second scroll end, the exhaust angle being 5°±3°;   the blower wall having an angle at cut-off, the angle at cut-off being the angle between a cut-off reference line and the cut-off, the cut-off reference line being perpendicular to the second radial scroll line and extending from the second radial scroll line through the cut-off, the angle at cut-off being 25°±5°;   the blower wheel being within the scroll housing.   
     
     
         13 . The blower fan assembly of  claim 12  wherein the scroll housing as a cut-off angle of 68°±5°, an exhaust angle of 5°±1°, and an angle at cut-off of 25°±3. 
     
     
         14 . The blower fan assembly of  claim 12 , wherein the forward-curved blower wheel comprises a plurality of fan blades circumferentially spaced about the blower wheel axis, each of the fan blades having a leading edge and a trailing edge, the blower wheel having an inner radius, the inner radius of the blower wheel being the radial distance between the blower wheel axis and the leading edge of each fan blade, the blower wheel having an outer radius, the outer radius of the blower wheel being the radial distance between the blower wheel axis and the trailing edge of each fan blade, the leading edge of each fan blade having a leading edge angle, the leading edge angle being the angle between a first tangent line and a first reference line, the first tangent line being a line tangent to the camber line at the leading edge, the first reference line intersecting the leading edge and being perpendicular to a first radial line extending from the blower wheel axis to the leading edge, the first tangent line and the first reference line being in a plane perpendicular to the blower wheel axis, the trailing edge of each fan blade having a trailing edge angle, the trailing edge angle being the angle between a second tangent line and a second reference line, the second tangent line being tangent to the camber line at the trailing edge, the second reference line intersecting the trailing edge and being perpendicular to a second radial line extending from the blower wheel axis to the trailing edge, the second tangent line and the second reference line being in a plane perpendicular to the blower wheel axis, the leading edge angle being at least 50° and not more than 80° and the trailing edge angle being at least 5.5° and not more than 18.5°, the outer radius being not more than 4 inches (101.6 mm). 
     
     
         15 . The blower fan assembly of  claim 14  wherein the plurality of fan blades comprises 40 blades. 
     
     
         16 . The blower fan assembly of  claim 14  wherein the blower wheel further comprises a first blower wheel inlet, a second blower wheel inlet, a first internal cavity, a second internal cavity, and a center disc, the first blower wheel inlet being axially aligned with the fan axis, the first internal cavity being bounded by the first blower wheel inlet and the leading edges of the fan blades, the second blower wheel inlet being axially aligned with the fan axis, the second internal cavity being bounded by the second blower wheel inlet and the leading edges of the fan blades, the center disc being axially between and axially spaced from the first and second blower wheel inlets and separating the first internal cavity from the second internal cavity. 
     
     
         17 . A scroll housing having a blower wall and opposite axial sides, the blower wall having a scroll profile as viewed in a plane perpendicular to the blower wheel axis, the blower wall extending axially from one of the axial sides to the other of the axial sides, the scroll profile of the blower wall extending circumferentially from a first scroll end to a second scroll end, the blower wall having a cut-off at the first scroll end, the scroll housing having a cut-off angle, the cut-off angle being an angle between a first radial scroll line extending from the blower wheel axis to the first scroll end and a second radial scroll line extending from the blower wheel axis to the second scroll end, the cut-off angle being 68°±10°;
 the blower wall having an exhaust wall portion extending generally straight from the second radial scroll line and an exhaust angle, the exhaust angle being the angle between the exhaust wall portion and an exhaust line, the exhaust line being perpendicular to the second radial scroll line and intersecting the second scroll end, the exhaust angle being 5°±3°; 
 the blower wall having an angle at cut-off, the angle at cut-off being the angle between a cut-off reference line and the cut-off, the cut-off reference line being perpendicular to the second radial scroll line and extending from the second radial scroll line through the cut-off, the angle at cut-off being 25°±5°. 
 
     
     
         18 . A forward curved blower wheel comprising a plurality of fan blades circumferentially spaced about the blower wheel axis, each of the fan blades having a leading edge and a trailing edge, the blower wheel having an inner radius, the inner radius of the blower wheel being the radial distance between the blower wheel axis and the leading edge of each fan blade, the blower wheel having an outer radius, the outer radius of the blower wheel being the radial distance between the blower wheel axis and the trailing edge of each fan blade, the leading edge of each fan blade having a leading edge angle, the leading edge angle being the angle between a first tangent line and a first reference line, the first tangent line being a line tangent to the camber line at the leading edge, the first reference line intersecting the leading edge and being perpendicular to a first radial line extending from the blower wheel axis to the leading edge, the first tangent line and the first reference line being in a plane perpendicular to the blower wheel axis, the trailing edge of each fan blade having a trailing edge angle, the trailing edge angle being the angle between a second tangent line and a second reference line, the second tangent line being tangent to the camber line at the trailing edge, the second reference line intersecting the trailing edge and being perpendicular to a second radial line extending from the blower wheel axis to the trailing edge, the second tangent line and the second reference line being in a plane perpendicular to the blower wheel axis, the leading edge angle being at least 50° and not more than 80° and the trailing edge angle being at least 5.5° and not more than 18.5°, the outer radius being not more than 4 inches (101.6 mm). 
     
     
         19 . The forward curved blower wheel of  claim 18  wherein the leading edge angle is 60°, the trailing edge angle is 18.25°, and wherein each fan blade has a stagger angle and a chord line, the stagger angle being the angle between the chord line and a radial line extending from the axis of rotation and intersecting the leading edge, the stagger angle being 30°. 
     
     
         20 . The forward curved blower wheel of  claim 18  wherein the leading edge angle is 70° and the trailing edge angle is 6.5°, and wherein each fan blade has a stagger angle and a chord line, the stagger angle being the angle between the chord line and a radial line extending from the axis of rotation and intersecting the leading edge, the stagger angle being 30°.