Patent ID: 9388825
Filing Date: 2016-07-12
CPC Classification: F04D,F24F

Claim Text:
1. A ventilation fan with automatic blade closure mechanism, comprising: a motor having a central rotor and a stator surrounding the rotor; a shaft extending axially through the rotor, the shaft having a first end and a second end opposite the first end, the shaft being rotationally affixed to the rotor; a hub rotationally affixed to the first end of the shaft; a plurality of fan blade spars extending radially from the hub, each of the fan blade spars being pivotally disposed upon the hub; a fan blade affixed to each of the spars, each fan blade having a blade tip, each fan blade spar and corresponding fan blade selectively pivoting between a fan operative positive pitch angle and a fan inoperative flat pitch; a stationary rim surrounding the fan blades, the rim defining a vent opening, the vent opening having a diameter substantially equal to a fan diameter, the fan blades substantially closing the vent opening when the ventilation fan is inoperative; and a fan blade pitch control mechanism whereby each fan blade pivots to a positive pitch angle when the ventilation fan is in operation, each fan blade further pivoting to a flat pitch when the ventilation fan is inoperative, wherein the fan blade pitch control mechanism comprises: