Automatic air conditioning system for an automotive vehicle

Claim 1

An automatic air conditioning system for an automotive vehicle comprising: an air induction system including a cool air source and a hot air source; a first air mix chamber connecting said induction system and a first lower air outlet; a second air mix chamber connecting said induction system and a second upper air outlet; a first means for controlling the proportions of cool air and hot air delivered by said induction system to said first and second air mix chambers; a passage connecting the outlet of said hot air source to said first and second air mix chambers, said passage including a first end opening to said first air mix chamber and a second end opening to said second air mix chamber; first and second shutter doors respectively adapted to open and close said first and second air outlets, each of said first and second shutter doors being movable between a first position in which it closes the corresponding one of said first and second air outlets and a second position in which it opens the corresponding air outlet; a temperature selecting means for designating a desired room temperature to which the passenger compartment air temperature is to be adjusted; a second means for detecting at least one preselected external condition and deriving the heat value required to adjust the room temperature to said designated desired room temperature; an air flow control means for controlling a flow rate of cool air and hot air to said first and second chambers on the basis of said heat value; and a mode selector means, responsive to said second means, for deriving a control signal to operate said first and second shutter doors to corresponding ones of said first and second positions in accordance with the derived heat value, said mode selector means comparing said heat value with a first heating/cooling selector criterion which is a criterion for determining a heating condition requiring addition of heat to the room air and a cooling condition requiring removal of heat from the room air, a second cooler mode selecting criterion so as to operate said first shutter door to said first position and said second shutter door to said second position when said heat value is greater than said first heating/cooling selector criterion and is greater than said second cooler mode selecting criterion, with a third heater mode selecting criterion so as to operate said first shutter door to said second position and said second shutter door to said first position when said heat value is smaller than said first heating/cooling selector criterion and is smaller than said third heater mode selecting criterion, and said mode selector means operating said first and second shutter doors to said second position when said heat value is greater than said third criterion and is smaller than said second criterion, and said mode selector means varying the heat value difference between said second cooler mode selecting criterion and said third heater mode selecting criterion depending upon said designated desired room temperature.