US Patent 6840055 Air conditioner for hybrid vehicle

In an air conditioner for a hybrid vehicle, an air conditioning unit performs air-conditioning operation by electrical power supplied from a battery. When a residual charging degree of the battery becomes equal to or lower than a charging-starting target value, an electrical generator is driven by a vehicle engine so that the battery is charged through the electrical generator. Further, when the battery is in a discharging mode, the control unit decreases an air-conditioning capacity of the air conditioning unit, as compared with that in a charging mode of the battery. Accordingly, a frequency for consuming the engine for charging the battery can be reduced. Therefore, a fuel consumption efficiency can be effectively improved and a total discharge amount of environmental destruction substance contained in exhaust gas of the engine can be effectively reduced.