This invention relates generally to climate control systems and specifically to an automotive vehicle climate control system within which the air temperature and/or air volume exiting from two air outlets can be independently controlled.
In automotive vehicles, it is common to have a climate control system located within an instrument panel which provides heated or cooled air to front seat occupants through dash panel defrost air outlets, instrument panel venting air outlets and floor directed air outlets. These traditional climate control systems often include a centralized duct and air outlet extending between or below the front occupant seats to supply heated or cooled air to rear seat passengers. Examples of such automotive vehicle climate control systems are disclosed within the following U.S. Pat. Nos.: 5,392,845 entitled "Air-Conditioning Device" which issued to Honda et al. on Feb. 28, 1995; 5,390,728 entitled "Air Conditioner for Use in a Vehicle" which issued to Ban on Feb. 21, 1995; 5,337,802 entitled "Vehicle Air Conditioner Having Driver and Passenger Units Which Operate Independently of One Another" which issued to Kajino et al. on Aug. 16, 1994; 5,237,828 entitled "Air-Conditioner for an Automobile with Non-Azeotropic Refrigerant Mixture Used to Generate "Cool Head" and "Warm Feet" Profile" which issued to Kutsuna on Aug. 24, 1993; 5,042,567 entitled "Air Conditioner for a Vehicle" which issued to Kajimoto et al. on Aug. 27, 1991; 4,940,083 entitled "Apparatus for Conditioning Air for a Vehicle Compartment" which issued to Takenaka et al. on Jul. 10, 1990; 4,913,347 entitled "Air-Conditioning System for an Air-Cooled Motor Vehicle" which issued to Burst et al. on Apr. 3, 1990; 4,899,809 entitled "Automotive Air Conditioner System with Automatic Adjustment of Discharge Air Temperature" which issued to Takenaka et al. on Feb. 13, 1990; 4,898,325 entitled "Automobile Air Conditioner with Separate Flow Adjustment for Central and Side Vents" which issued to Sakurada on Feb. 6, 1990; 4,340,112 entitled "Vehicle Air Temperature Control Apparatus" which issued to Sutoh et al. on Jul. 20, 1982; 3,934,642 entitled "Vehicle Air Conditioning System" which issued to Coulson et al. on Jan. 27, 1976; and 3,881,546 entitled "Air Conditioner for Automotive Vehicles" which issued to Otsuka et al. on May 6, 1975. A limitation of most, if not all, of these traditional climate control systems is that the air temperature and air volume exiting from different outlets cannot be separately controlled due to common heat exchanger or blower components disposed within the unit.
A further limitation is apparent with regard to climate control systems employed within semi-tractor trucks, also known as class 8 trucks, which have a sleeper compartment and a cab containing front occupant seats. A pair of separately located climate control units are usually provided within these long distance trucks, one unit for heating and cooling the front cab and another unit for heating and cooling the sleeper compartment. Thus, a cab blower, evaporator and heater are located near or in an instrument panel while a rear blower, evaporator and heater are located within the sleeper compartment. One such example of this type of truck environmental control system is disclosed within U.S. Pat. No. 5,333,678 entitled "Auxiliary Power Unit" which issued to Mellum et al. on Aug. 2, 1994; the disclosure of which is incorporated by reference herewithin.
Another known tractor truck environmental control unit has been integrated into a single unit for positioning beneath a passenger front occupant seat within the truck's cab. The unit is mounted to a floor and subfloor within the cab while the passenger seat is affixed on top of a housing for this unit. Within this truck environmental control system, a pair of blowers push air from a common inlet, through a single evaporator, then through a single heater arranged downstream of the evaporator, after which, a portion of the heated or cooled air is allowed to exit from a front air outlet; concurrently, another portion of the air is directed out of a rear air outlet by another blower arranged downstream of the heater. It is believed that the air within this unit flows in a generally circular pattern between the air inlet and the rear air outlet. All of the air within this unit flows through the evaporator and most, if not all of the air within the unit flows through the heater core. Accordingly, a water valve and a heater air bypass door are used to control and vary the heater core performance, however, this is a fairly inaccurate method of temperature regulation. It is further believed that the air flow pattern within this truck climate control unit is overly complex and inefficient. Additionally, the air temperature exiting from the front and rear air outlets cannot be independently controlled but the air volume can be independently controlled.
Also of interest, a dual environmental control system employed in a bus is disclosed within U.S. Pat. No. 4,622,831 entitled "Air-Conditioning Plant for Motor Vehicles, Especially for Buses" which issued to Grupa on Nov. 18, 1986. Other conventional heating and air conditioning systems and their reversing air flow patterns are disclosed within U.S. Pat. Nos. 4,874,036 entitled "Heating and Air Conditioning System for a Forklift" which issued to Masuda on Oct. 17, 1989, and 4,401,013 entitled "Air Conditioning Device" which issued to Ohashi et al. on Aug. 30, 1983.
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