Patent ID: 8231335

Claim:
An air inlet cover comprising a grille having: a plurality of radial elements radiating from a center of said grille, each said radial element comprising a vane having a leading edge for positioning further from a fan and a trailing edge for positioning closer to a fan, the leading edge of each said vane being offset from the respective trailing edge thereof by substantially the same angular amount for each said vane, whereby the vanes are pitched more steeply closer to the center of said grille than remote from the center of said grille, and a circumferential element comprising a bell-shaped mouth enclosing said vanes and having a plurality of apertures formed in a surface thereof, each respective one of said apertures having a first edge parallel to the pitch of a first respective vane closer to the center of said grille and a second edge parallel to the pitch of a second, adjacent respective vane remote from the center of said grille.