Flapper linkage in air intake control system of internal combustion engine

A device for controlling the combustion air temperature in the air intake system of an internal combustion engine, comprising a pivotable flapper which serves as a flow proportioning valve at a duct junction between an intake duct for preheated raw air and an intake duct for raw air of ambient temperature, leading to a raw air mixing duct downstream of the duct junction, the flapper being operable to progressively open and close one of the two raw air intake ducts while correspondingly closing and opening the other, as a result of being connected to a flapper drive assembly which is capable of adjusting the angular position of the flapper in response to changes in the temperature of the combustion air which is taken in by the internal combustion engine, in such an air temperature controlling device, the improvement comprising:

• as part of the flapper, a flapper pivot axis, a flapper wall of generally flat configuration extending parallel to the flapper pivot axis, and a connecting cylinder formed by protrusions of the flapper wall, the cylinder axis being parallel to the flapper pivot axis;
• and
• as part of the flapper drive assembly, a drive member with a drive member extension whose axis is oriented transversely to the plane of the flapper wall and which has an end portion defining a recess with two oppositely facing positioning flanks oriented substantially perpendicularly to the axis of the drive member extension and engaging opposite sides of the connecting cylinder of the flapper, said engagement thereby allowing for lateral shifting of the connecting cylinder relative to the axis of the drive member extension, in order to accommodate arcuate displacements of the connecting cylinder about the flapper pivot axis in conjunction with substantially straight displacements of the flapper drive assembly.