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.

1 ) A method of optimizing an air conditioning system control in a vehicle comprising momentarily reducing air conditioner condenser heat load via electric compressor speed control, forced cabin recirculation, and/or reduced cabin blower speed during transient, high ambient and high propulsion system load events. 
     
     
         2 ) A method according to  claim 1 , wherein all three of electric compressor speed control, forced cabin recirculation, and reduced cabin blower speed are performed. 
     
     
         3 ) A method of optimizing an air conditioning system control in an air conditioning system for a vehicle, comprising the steps of:
 I) checking:
 1) whether the temperature of the engine coolant is higher than a first engine coolant temperature limit and lower than a second engine coolant temperature limit, 
 2) whether the temperature of the transmission oil is higher than a first transmission oil temperature limit and lower than a second transmission oil temperature limit,
 Ia) if the answer to 1 or 2 is yes, then repeating I), 
 Ib) if the answer to 1 or 2 is no, then proceeding to step II), 
 
   II) reducing air conditioner heat load by:
 1) increasing cabin recirculation of air 
 2) reducing cabin blower speed 
 3) reducing air conditioner compression 
   III) after step II), checking
 1) whether the engine coolant temperature is higher than the second engine coolant temperature limit; and 
 2) whether the transmission oil temperature of the transmission oil is higher than the second temperature limit;
 IIIa) if the answer to 1 or 2 is yes, then shutting off the A/C compressor, setting a flag and then repeating step III), 
 IIIb) if the answer is no, then checking for the presence of the flag,
 IIIbi) if the flag is present, performing cabin recirculation, limiting cabin blower speed and reducing compressor capacity followed by repeating step I), 
 IIIbii) if no flag is present, repeating step I). 
 
 
   
     
     
         4 ) The method according to  claim 3 , wherein the temperature limits are predetermined values. 
     
     
         5 ) The method according to  claim 3 , wherein in step II) cabin recirculation of air is increased by X %, cabin blower speed is increased by Y %, and compressor capacity is reduced by Z %. 
     
     
         6 ) The method according to  claim 3 , wherein X, Y and Z are predetermined values. 
     
     
         7 ) The method according to  claim 3 , wherein X, Y and Z are calculated values. 
     
     
         8 ) A method of designing vehicles comprising determining propulsion cooling system size which achieves predetermined performance while performing the method according to  claim 3 . 
     
     
         9 ) The method according to  claim 8 , wherein the cooling system size is reduced from a size the cooling system would have been without the vehicles performing a method according to  claim 3  while having the same predetermined performance, comprising:
 reducing radiator cooling size by core thickness reduction, fin density reduction, or core face area reduction; and   reducing fan motor power.   
     
     
         10 ) A method of optimizing an air conditioning system control in an air conditioning system for a hybrid or fuel cell vehicle, comprising the steps of:
 I) checking:
 1) whether the temperature of the engine coolant is higher than a first engine coolant temperature limit and lower than a second engine coolant temperature limit, 
 2) whether the temperature of the transmission oil is higher than a first transmission oil temperature limit and lower than a second transmission oil temperature limit, 
 3) whether the temperature of the inverter coolant is higher than a first inverter coolant temperature limit and lower than a second electric motor temperature limit, and 
 4) whether the temperature of the electric motor is higher than a first electric motor temperature limit and lower than a second electric motor temperature limit,
 Ia) if the answer to all of 1), 2) 3) and 4) checked is yes, then repeating I), 
 Ib) if the answer to any of 1), 2) 3) or 4) is no, then proceeding to step II), 
 
   II) reducing air conditioner heat load by:
 1) increasing cabin recirculation of air, or 
 2) reducing cabin blower speed, or 
 3) reducing air conditioner compressor capacity, 
   III) after step II), checking
 1) whether the engine coolant temperature is higher than the second engine coolant temperature limit; 
 2) whether the transmission oil temperature of the transmission oil is higher than the second temperature limit; 
 3) whether the inverter coolant temperature of the inverter coolant is higher than the second inverter coolant temperature limit; 
 4) whether the electric motor temperature of the electric motor is higher than the second electric motor temperature limit;
 IIIa) if the answer to any of 1), 2) 3) or 4) is yes, then shutting off the A/C compressor, setting a flag and then repeating step II), 
 IIIb) if the answer to all of the parameters that have been checked is no, then checking for the presence of the flag,
 IIIbi) if the flag is present, performing cabin recirculation, limiting cabin blower speed and reducing compressor capacity followed by repeating step I), 
 IIIbii) if no flag is present, repeating step I). 
 
 
   
     
     
         11 ) The method according to  claim 3 , wherein the temperature limits are predetermined values. 
     
     
         12 ) The method according to  claim 3 , wherein the temperature limits are calculated values. 
     
     
         13 ) A method of designing vehicles comprising determining propulsion cooling system size which achieves predetermined performance while performing the method according to  claim 10 . 
     
     
         14 ) The method according to  claim 13 , wherein the cooling system size is reduced from a size having the same predetermined performance, comprising:
 reducing radiator cooling size by core thickness reduction, fin density reduction, or core face area reduction; and   reducing fan motor power.   
     
     
         15 ) The method of  claim 14  wherein the vehicle is a hybrid or fuel cell vehicle and the method further comprises:
 reducing power electronics radiator size by core thickness reduction, fin density reduction, and core face area reduction, and   reducing electric motor cooler size by reduced core thickness, fin density reduction, and core face area reduction.   
     
     
         16 ) A method of optimizing an air conditioning system control for an air conditioning system having a compressor in hybrid or fuel cell having an electric drive motor, the method comprising:
 determining the operating temperature of at least one of the following vehicle components: engine coolant, transmission oil, inverter coolant and the electric drive motor;   comparing the at least one operating temperature to lower and upper temperature limits;   if the operating temperature is outside of the temperature limits reducing air conditioner heat load by at least one fo the following steps: increasing cabin air recirculation, reducing cabin blower speed and reducing air conditioner compressor capacity;   subsequent to reducing air conditioner heat load, monitoring the operating temperature to determine if the operating temperature exceeds the upper temperature limit,   shutting off the compressor if the operating temperature exceeds the upper limit;   repeating the step of determining the operating temperature, and   restarting the compressor once the operating temperature is below the upper temperature limit to recirculate conditioned air a limited blower speed on reduced compressor capacity.   
     
     
         17 ) The method of  claim 16  wherein the operating temperatures of at least two of the vehicular components are determined. 
     
     
         18 ) The method of  claim 16  wherein the operating temperatures of three of the vehicular, components are determined. 
     
     
         19 ) The method of  claim 16  wherein the operating temperatures of four of the vehicular components are determined.