Heating and ventilating system for the occupant compartment of a motor vehicle

Heating and ventilating system for the occupant compartment of motor vehicles, including a blower supplied with ambient air, a hot air duct extending past a heat exchanger, a cold air bypass, a mixing chamber, controllable valves and doors and air vents or air discharge nozzles disposed in the area of a dashboard and leg room for the occupants, wherein air currents of different temperatures are traversing in ducts mounted adjacent to one another, and wherein, for the purpose of mixing the air currents with one another, an opening is provided between the adjacent ducts which is adapted to be closed by a flap valve, the improvement comprising:

• flap valve means responsive to the air flow rate prevailing in a first duct in a manner to cause progressive opening of the flap valve means as the flow rate increases, so that with increasing air flow rate in the first duct, a progressively increasing volume of air is permitted to pass from a second duct over into the first duct,
• and the first duct being provided, for the purpose of creating a vacuum in the area above the flap valve means with air guide means which causes a restriction of the cross-sectional area of the first duct so that an increase in the air flow rate occurs in the narrowest cross-sectional area of the first duct.