Motor vehicle heating and ventilating air distribution unit - has heated and unheated incoming air mixed for general delivery, with special provision for windscreen defrosting

摘要

The heating/ventilating unit includes a motor-driven fan which delivers exterior, or conditioned, air to a divided intake (14,16). A cold air transmitting branch (18) passes unheated air to the mixing area (46), and a heated air branch (20) is interposed between the cold air branch and a mixing area. Some heated air, traversing a heat exchanger (34) in the engine coolant circuit, reaches this area via a reverse-flow section (28). The relative proportions are controlled by a double-flap (56,58) pivoted (54) shutter (52), which in extreme positions completely blocks either air-flow (56-64;58-70). Mixed air is delivered to the vehicle windscreen (42), dashboard (50) and foot-well (44) outlets, the distribution being determined by adjustable shutters (66,76). An enclosed duct (68) within the mixing area receives a direct supply of heated, unmixed air, which, with suitable shutter settings (58,76) gives a higher delivery temperature to the windscreen outlets (42).