Climate thermal load based minimum flow rate water pump control

Abstract

A control system for minimizing the flow rate and energy consumption of a water pump in a vehicle. The control system and method correlate a climate thermal load value with the temperature of the coolant in a climate control cooling circuit. A correlation is performed by mapping the inputs to a desired pump flow rate that is determined to be necessary at a minimum to provide adequate cooling for the engine and for air conditioning or heating the vehicle.

1 . A system for controlling a water pump in a vehicle comprising:
 an electric motor operating the water pump;   a controller configured to generate a heater core flow request signal as a function of a climate thermal load and a heater coolant temperatures and provide a signal to the electric motor to set a pump flow rate to satisfy the heater core flow request.   
     
     
         2 . (canceled) 
     
     
         3 . The system of  claim 1  wherein the climate thermal load is based upon a cabin temperature set point, and ambient air temperature. 
     
     
         4 . The system of  claim 1  wherein the heater coolant temperature is obtained from a thermal sensor that senses temperature of coolant at an inlet to a heater core. 
     
     
         5 . The system of  claim 1  wherein the pump flow rate is selected to minimize power consumption by the electric motor. 
     
     
         6 - 7 . (canceled) 
     
     
         8 . The system of  claim 1  wherein the climate thermal load is obtained from a vehicle bus. 
     
     
         9 . A method of controlling a water pump in a vehicle comprising:
 setting the water pump at maximum flow responsive to a maximum defrost input being actuated;   responsive to the maximum defrost input and an HVAC input not being actuated, setting the water pump to no flow; and   responsive to the HVAC input being actuated, integrating a climate thermal load value and a heater coolant temperature value using a multiple variable table to select a heater core flow rate, and responsive to the heater core flow rate being greater than a threshold value, providing a signal to an electric motor that controls the flow rate of the water pump.   
     
     
         10 . The method of  claim 9  wherein the threshold value is zero. 
     
     
         11 . The method of  claim 9  wherein the HVAC input includes a thermistor and a variable temperature selector switch for controlling the temperature of a passenger compartment. 
     
     
         12 . The method of  claim 9  wherein the integrating includes selecting a heater core flow rate based upon a table of values corresponding to a plurality of climate thermal load values and a plurality of heater coolant temperature values. 
     
     
         13 . The method of  claim 9  wherein the climate thermal load value is based upon a cabin temperature set point, and ambient air temperature. 
     
     
         14 . The method of  claim 9  wherein the heater core flow rate is selected to minimize power consumption by the electric motor. 
     
     
         15 . A vehicle comprising:
 a single water pump;   an electric motor configured to drive the water pump; and   a controller configured to
 provide a coolant flow request value to the water pump that is set to a maximum responsive to presence of a maximum defrost setting, and that is set to zero responsive to absence of a heat request, 
 command a heater core flow rate according to thermal load and coolant temperature values, and 
 map a heater core flow rate to a speed of the water pump responsive to the heater core flow rate being greater than zero. 
   
     
     
         16 - 19 . (canceled) 
     
     
         20 . The system of  claim 15  wherein the thermal load value is based upon a cabin temperature sensor signal, a cabin temperature set point, an ambient temperature signal, and a sun load sensor signal.