Method and system for controlling cooling fans in a vehicle

Abstract

A system and method is disclosed for cooling a control system in a vehicle. In one embodiment, the system comprises vehicle subsystems and a vehicle controller. The vehicle subsystems are configured to generate a plurality of subsystem temperature signals that are indicative of a measured temperature for each vehicle subsystem. The vehicle controller is configured to generate a desired fan speed signal for each vehicle subsystem in response to each subsystem temperature signal and to compare each desired fan speed signal to each other to determine a maximum desired fan speed signal. The vehicle controller controls the fan such that the fan reaches a fan speed that is equal to or greater than the maximum desired fan speed signal.

1 . A system for controlling fan speed for a cooling fan in a vehicle; the system comprising:
 a plurality of vehicle subsystems configured to generate a plurality of subsystem temperature signals that are indicative of a measured temperature for each vehicle subsystem; and   a vehicle controller configured to generate a desired fan speed signal for each vehicle subsystem in response to each subsystem temperature signal and to compare each desired fan speed signal to each other to determine a maximum desired fan speed signal, wherein the vehicle controller controls the fan to reach a speed that is equal to or greater than the maximum desired fan speed signal.   
   
   
       2 . The system of  claim 1  wherein the vehicle controller is further adapted to compare the maximum desired fan speed signal to a first predetermined fan speed and to set the fan speed to a high speed if the maximum desired fan speed signal is greater than or equal to the first predetermined fan speed. 
   
   
       3 . The system of  claim 2  wherein the vehicle controller is further adapted to compare the maximum desired fan speed signal to a second predetermined fan speed and to set the fan speed to a low speed if the maximum desired fan speed signal is less than the second predetermined fan speed. 
   
   
       4 . The system of  claim 3  wherein the vehicle controller is further adapted to set the fan speed to a medium speed if the maximum desired fan speed signal is greater than the second predetermined fan speed and less than the first predetermined fan speed. 
   
   
       5 . The system of  claim 1  wherein the vehicle subsystems comprise an engine controller and an engine, the engine controller being adapted to measure temperature of the engine and to generate an engine temperature signal, the vehicle controller is configured to determine an engine fan speed signal in response to the engine temperature signal. 
   
   
       6 . The system of  claim 1  wherein the vehicle subsystems comprise a transmission controller and a transmission, the transmission controller being adapted to measure temperature of the transmission and to generate a transmission temperature signal, the vehicle controller is configured to determine a transmission fan speed signal in response to the transmission temperature signal. 
   
   
       7 . The system of  claim 1  wherein the vehicle subsystems comprise a generator controller and a starter-generator, the generator controller being adapted to measure temperature of the starter-generator and to generate a starter-generator temperature signal, the vehicle controller is configured to determine a generator fan speed signal in response to the starter-generator temperature signal. 
   
   
       8 . The system of  claim 7  wherein the generator controller comprises power electronic circuitry, the generator controller being adapted to measure temperature of the power electronic circuitry and to generate a power electronic circuit temperature signal, the vehicle controller is configured to determine a power electronic fan speed signal in response to the power electronic circuit temperature signal. 
   
   
       9 . The system of  claim 1  wherein the vehicle subsystems comprise a DC/DC converter adapted to measure an internal operating temperature and to generate a converter temperature signal, the vehicle controller is configured to determine a converter fan speed signal in response to the converter temperature signal. 
   
   
       10 . The system of  claim 1  wherein the vehicle subsystem comprises a motor controller and a motor, the motor controller being adapted to measure the temperature of the motor to generate a motor temperature signal, the vehicle controller is configured to determine a motor fan speed signal in response to the motor temperature signal. 
   
   
       11 . A method for controlling fan speed for a cooling fan in a vehicle, the method comprising the steps of:
 generating a plurality of subsystem temperature signals for a plurality of vehicle subsystems that are indicative of a measured temperature for each vehicle subsystem;   generating a desired fan speed signal for each vehicle subsystem;   comparing each desired fan speed signal to each other to determine a maximum desired fan speed signal; and   controlling the fan such that the fan reaches a fan speed that is equal to or greater than the maximum desired fan speed signal.   
   
   
       12 . The method of  claim 11  further comprising comparing the maximum desired fan speed to a first predetermined fan speed and controlling the fan speed to a high speed in response to determining that the maximum desired fan speed is greater than the first predetermined fan speed. 
   
   
       13 . The method of  claim 12  further comprising comparing the maximum desired fan speed to a second predetermined fan speed and controlling the fan speed to a low speed in response to determining that the maximum desired fan speed is less than the second predetermined fan speed. 
   
   
       14 . The method of  claim 13  wherein further comprising controlling the fan speed to a medium speed in response to the determining that the maximum desired fan speed is greater than the second predetermined fan speed and less than the first predetermined fan speed. 
   
   
       15 . The method of  claim 11  wherein the vehicle subsystems comprise an engine controller and an engine, the engine controller being adapted to measure temperature of the engine and to generate an engine temperature signal, the vehicle controller is configured to determine an engine fan speed signal in response to the engine temperature signal. 
   
   
       16 . The method of  claim 11  wherein the vehicle subsystems comprise a transmission controller and a transmission, the transmission controller being adapted to measure temperature of the transmission and to generate a transmission temperature signal, the vehicle controller is configured to determine a transmission fan speed signal in response to the transmission temperature signal. 
   
   
       17 . The method of  claim 11  wherein the vehicle subsystems comprise a generator controller, a starter-generator, a motor controller and a motor, the generator controller is adapted to measure temperature of the starter-generator and to generate a starter-generator temperature signal, the motor controller is adapted to measure the temperature of the motor to generate a motor temperature signal, and the vehicle controller is configured to determine a generator fan speed signal in response to the starter-generator temperature signal and to determine a motor fan speed signal in response to the motor temperature signal. 
   
   
       18 . The method of  claim 17  wherein the generator controller comprises power electronic circuitry, the generator controller being adapted to measure temperature of the power electronic circuitry and to generate a power electronic circuit temperature signal, the vehicle controller is configured to determine a power electronic fan speed signal in response to the power electronic circuit temperature signal. 
   
   
       19 . The method of  claim 11  wherein the vehicle subsystems comprise a DC/DC converter adapted to measure an internal operating temperature and to generate a converter temperature signal, the vehicle controller is configured to determine a converter fan speed signal in response to the converter temperature signal. 
   
   
       20 . A system for cooling a control system in a vehicle, the system comprising:
 a cooling fan;   a plurality of cooling loops;   a plurality of vehicle subsystems configured to generate a plurality of subsystem temperature signals that are indicative of a measured temperature for each vehicle subsystem, the vehicle subsystems being positioned about the plurality of cooling loops; and   a vehicle controller configured to:
 control the plurality of cooling loops to cool the vehicle subsystems in response to each subsystem temperature signal; 
 generate a desired fan speed signal for each vehicle subsystem in response to each subsystem temperature signal; 
 compare each desired fan speed signal to each other to determine a maximum desired fan speed signal; and 
 control the fan such that the fan reaches a speed that is equal to or greater than the maximum desired fan speed signal.