Patent Document ID: 5553776
Application ID: 08361407
Patent Flag: 1

Claim One:
1. A method for economically controlling a heating, ventilation and air conditioning (HVAC) system of a vehicle which discharges a flow of air to a passenger cabin of the vehicle, the system including a variable speed blower, ducting, cooling means for cooling air in the ducting, a control element having control positions for varying refrigerating capacity of the cooling means, actuators having various control position for controlling the direction of air flow and the ratio of fresh air to recirculated air, a humidity sensor for sensing relative humidity within the cabin and providing a corresponding relative humidity signal, and temperature sensors for sensing temperature within the cabin and providing a corresponding temperature signal, and for sensing ambient temperature and a target set point temperature, the method comprising the steps of: processing the temperature and relative humidity signals to obtain processed temperature and relative humidity signals; estimating a single enthalpy of air within the cabin based on the processed temperature and relative humidity signals; defining membership functions and fuzzy rules between the single enthalpy of air within the cabin and the control positions of the control element; and generating a control signal to control the positions of the control element to cause the system to economically discharge air into the cabin having a desired temperature and flow based on the single enthalpy of air within the cabin, the membership functions and the fuzzy rules.