Patent ID: 6880807

Claim:
A flap valve for controlling a gas flow, comprising a valve tube ( 11 ) that conveys the gas flow and that has at least one elastically deformable, hollow cylindrical tube section, a valve flap ( 12 ) disposed inside the tube section for movement between an open position and a closed position, the valve flap ( 12 ) having a principal plane ( 123 ) which in its closed position covers over an inner valve tube cross section ( 112 ) and in its open position maximally unblocks this valve tube cross section, and a flap shaft ( 13 ) that can be driven in order to adjust the valve flap ( 12 ), the flap shaft ( 13 ) being disposed at an acute angle (α) in relation to the axis ( 111 ) of the valve tube ( 11 ), to which shaft the valve flap ( 12 ) is fastened so that in its closed position, an axis, which is referred to as the flap normal (n K ) and extends at right angles from the principal plane ( 123 ) of the flap, encloses an acute angle with the axis ( 111 ) of the valve tube ( 11 ), the valve flap ( 12 ) having an outer contour extending in the principal plane ( 123 ) of the flap, which contour is at least approximately oval in shape.