Air flow switching device

The airflow switching device has a pivotable switching flap valve (2) with a concave circle segment section (16). The flap in a first end position communicates a first air duct (4) with a second air duct (5), while a third air duct (6) is closed off, and in a second end position communicates the first air duct with the third, while the second duct is closed off. In an intermediate position the flap communicates more or less the first air duct with both the second duct and also the third duct. The flap valve is mounted so that the circle middle point of the circle segment section coincides with the pivot axis (15).