Patent ID: 7617692

Claim:
A method for operating a hybrid vehicle, the method comprising: determining whether a hybrid vehicle is at idle or is being driven; determining an operating mode of a climate control system of the vehicle, wherein the climate control system is operable at a given time in one of at least two different operating modes; determining whether an A/C compressor of the climate control system is required to be turned on in order to maintain air conditioning comfort in the vehicle, wherein the A/C compressor is turned on when the A/C compressor is coupled to an engine of the vehicle and the engine is turned on, wherein the A/C compressor is turned off when either the A/C compressor is uncoupled from the engine or the engine is turned off, wherein both the A/C compressor and the engine are initially turned on; wherein determining whether the A/C compressor is required to be turned on includes comparing an ambient temperature in the vehicle to an ambient temperature threshold respectively associated with the operating mode of the climate control system and determining that the A/C compressor is required to be turned on if the ambient temperature is greater than the ambient temperature threshold; wherein, if the ambient temperature is less than the ambient temperature threshold, determining whether the A/C compressor is required to be turned on further includes comparing a duty cycle of the A/C compressor after the A/C compressor has been turned on for a period of time to a duty cycle threshold respectively associated with the operating mode of the climate control system, determining that the A/C compressor is required to be turned on if the duty cycle of the A/C compressor is greater than the duty cycle threshold, and determining that the A/C compressor is not required to be turned on if the duty cycle of the A/C compressor is less than the duty cycle threshold; turning off the engine and thereby turning off the A/C compressor if the A/C compressor is not required to be turned on and if the vehicle is at idle; and turning off the A/C compressor without turning off the engine by uncoupling the A/C compressor from the engine if the A/C compressor is not required to be turned on and if the vehicle is being driven.