Patent ID: 7185878

Claim:
Control device for the throughput in a conduit portion defined by a wall and an internal passage, the control device comprising a flap composed of a plate-shaped body mounted on a rotary support shaft and displaceable between a position of maximum closure and a position of minimum closure by pivoting about said shaft, said control device including two obstructive structures projecting from an internal face of the wall of said conduit portion into the internal passage of said conduit portion, said obstructive structures being located on either side of a plane containing a longitudinal axis of said conduit portion and an axis of said rotary support shaft, one obstructive structure upstream and the other obstructive structure downstream of said rotary support shaft, each obstructive structure comprising a cooperating surface zone facing said flap and intimately mating with a revolution surface swept by at least one segment of the external peripheral edge of the body of the flap when pivoted, each obstructive structure, as viewed in section in planes perpendicular to the rotary shaft, having one side in the form of the arc of a circle corresponding to the cooperating surface zone and one inclined side sloping towards the internal face of the conduit portion, said inclined side of the obstructive structure located upstream of the rotary shaft being directed upstream, said inclined side of the obstructive structure located downstream of the rotary shaft being directed downstream, each obstructive structure having at least one indent opening in the cooperating surface zone and defining a passage section when the flap is in contact with said cooperating surface zone, the cooperating surface zone of each obstructive structure extending over an angular range no greater than 45° from the maximum closure position of said flap.