Controlled deflection flexible bladed fan

Claim 1

In an automotive cooling fan comprising a hub, a plurality of resilient blades which decamber as rotational speed increases extending radially relative to said hub, each said blade having spaced leading and trailing edges defined by the direction of fan rotation, and, respectively thereadjacent, leading and trailing portions, said blade extending transversely between said leading and trailing edges thereof and curved from an upstream position, defined by the direction of airflow, adjacent said leading edge to a downstream position adjacent said trailing edge presenting a transversely extending convex surface on the upstream side of said blade, and a resilient support member on the upstream side of said blade extending along and connected to said leading portion of said blade and extending transversely to a trailing position intermediate said leading and trailing edges of said blade, said support member also curved between its leading edge and trailing position in the same direction as said blade presenting a transversely extending convex surface on the upstream side of said support member and a concave surface facing the convex surface of said blade, that improvement in which: said support member is curved on a larger radius than that of said blade and said support member comprises a radially extending leading portion, tangent to said leading portion of said blade and progressively more spaced from said blade transversely toward said trailing position of said support member, and, between said leading portion and said trailing position of said support member, a radially discontinuous trailing portion thereof defining a plurality of radially spaced transversely extending, resilient, support fingers and a plurality of slots defined between said support fingers, wherein said blade decambers to the curved configuration of said support member at a predetermined rotational speed, limited resilient decambering of said blade and support member is permitted at rotational speeds higher than said predetermined rotational speed while generally conforming said blade to said support member curved configuration, and at rotational speeds below said predetermined rotational speed air is admitted between said bLade and said support member through said slots.