Methods of Optimizing Vehicular Air Conditioning Control Systems

Abstract

Air conditioning system controls are optimized for an air conditioning system having a compressor in IC engine vehicles and in hybrid or fuel cell vehicles having electric drive motors by first determining the operating temperature of at least one of the following vehicle components: engine coolant and transmission oil for all types of vehicles, and for hybrid or fuel cell vehicles also determining the operating temperature of inverter coolant and the electric drive motors. At least one operating temperature is then compared to lower and upper temperature limits. If the operating temperature is outside of the temperature limits air conditioner heat load is reduced by at least one of the following steps: increasing cabin air recirculation, reducing cabin blower speed and reducing air conditioner compressor capacity. Subsequent to reducing air conditioner heat load, selected operating temperature or temperatures are monitored to determine if the operating temperature exceeds the upper temperature limit or limits. If the operating temperature or temperatures exceed the upper limit or limits the compressor is shut off.

Description

FIELD OF THE INVENTION[0001]The present invention is directed to methods of optimizing vehicular air conditioning control systems. More particularly, the present invention is directed to such methods which result in reduced propulsion cooling system size in non-hybrid vehicles and lower operating temperature for coolant loops in hybrid and fuel cell vehicles.BACKGROUND OF THE INVENTION[0002]Conventional vehicle propulsion cooling systems include heat exchangers and fans, the size of which is based on propulsion system losses. Losses are absorbed by engine coolant, engine oil and transmission oil. Those losses typically are momentarily exacerbated when the vehicle operates on a steep gradient and / or is towing a trailer, especially when the ambient air temperature is high. With respect to hybrid and fuel cell vehicles, propulsion cooling loops require lower operating temperatures than conventional power train vehicles.[0003]Air conditioning condensers are typically the first heat exch...

AI Technical Summary

Benefits of technology

[0005]In view of the aforementioned considerations, the present invention optimizes air conditioning systems for vehicles by momentarily reducing A / C condenser heat load during transient, high ambient temperature / high propulsion system load events, thereby allowing an overall reduction in propulsion cooling system size.

[0007]1) reducing radiator cooling size, e.g., by core thickness reduction, fin density reduction, and / or core face area reduction;

[0008]2) reducing electric cooling fan size, e.g., by reduced fan motor power;

[0011]3b) reducing electric motor cooler size, e.g., by reduced core thickness, fin density reduction, and / or core face area reduction.

[0012]In another aspect, there is a reduction of mass and cost of propulsion cooling systems for the following vehicles: hybrid vehicles that have either an electric A / C compressor or an external capacity control A / C compressor; fuel cell vehicles that have either an electric A / C compressor or an external capacity control A / C compressor; and conventional power train vehicles that have an external capacity control A / C compressor; as well as conventional power train vehicles that have a fixed displacement A / C compressor.

[0013]In a further aspect, the realization of cabin air conditioning is maintained during propulsion system thermal excursions and improved fuel economy is realized due to, for example, reduced CRFM (Condenser Radiator Fan Module) electric fan power and CRFM mass.

Problems solved by technology

Those losses typically are momentarily exacerbated when the vehicle operates on a steep gradient and / or is towing a trailer, especially when the ambient air temperature is high.

In current production vehicles having power train controls, when propulsion cooling systems approach maximum temperature limits, A / C system control is typically limited to A / C compressor interrupt.

A / C compressor interrupt results in a complete loss of cabin cooling because the A / C system simply shuts off when propulsion system thermal limits are reached.

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