Patent ID: 7186080

Claim:
A blower for moving air at a volume flow rate, comprising: a volute housing that includes a curved inlet shroud, wherein the volute housing defines a discharge opening, and the curved inlet shroud defines an air inlet, wherein the air inlet has a inlet airflow cross-sectional area that lies substantially perpendicular to an outlet airflow cross-sectional area of the discharge opening; an impeller mounted for rotation about a rotational axis within the volute housing, wherein the impeller includes a plurality of curved fan blades such that upon the impeller rotating at a rotational speed in a forward rotational direction, the plurality of curved fan blades force the air in a downstream direction from the air inlet to the discharge opening, wherein each curved fan blade of the plurality of curved fan blades has an inner edge, a forward leaning outer edge that leans in the forward rotational direction, and a blade length that is substantially parallel to the rotational axis; an impeller outer radius extending between the rotational axis and the forward leaning outer edge of at least one of the plurality of curved fan blades, wherein the impeller outer radius is less than twice the blade length, and the blade length is less than twice the impeller outer radius so that the blower can provide a flow coefficient of between 9 and 52, wherein the flow coefficient is defined as the volume flow rate divided by a product of the impeller outer radius cubed times the rotational speed of the impeller, wherein the volume flow rate is in units of cubic feet per minute, the impeller outer radius is in units of feet, and the rotational speed is in units of revolutions per minute; an impeller inner radius extending between the rotational axis and the inner edge of at least one of the plurality of curved fan blades; a first curved surface disposed on the curved inlet shroud, wherein the first curved surface curves at a first radius about a first substantially circular centerline, wherein the first substantially circular centerline has a first centerline radius; and a second curved surface disposed on the curved inlet shroud and being downstream of the first curved surface, wherein the second curved surface curves at a second radius about a second substantially circular centerline, the second substantially circular centerline has a second centerline radius, the first centerline radius is greater than the impeller inner radius, the first centerline radius is greater than the second centerline radius, the second radius is less than the impeller outer radius, the second radius is less than the first radius, and the second centerline radius minus the second radius is less than the impeller inner radius.