Method to infer engine coolant temperature in cylinder head temperature sensor equipped vehicles

Abstract

The present invention provides a method of inferring the engine coolant temperature in cylinder head temperature sensor equipped vehicles including the steps of measuring the cylinder head temperature, calculating the engine coolant temperature from the measured cylinder head temperature as a function of at least one vehicle operational state, generating a signal for the calculated engine coolant temperature, and sending the generated signal to a display.

1. A method of inferring engine coolant temperature in cylinder head temperature sensor equipped vehicles comprising the steps of:
 measuring the cylinder head temperature;  
 calculating the engine coolant temperature from the measured cylinder head temperature as a function of at least one vehicle operational state;  
 generating a signal for the calculated engine coolant temperature; and  
 sending the generated signal to a display .  
 
     
     
       2. A method according to  claim 1 , wherein the vehicle operational state is  includes engine revolutions per minute. 
     
     
       3. A method according to  claim 2 , wherein the vehicle operational state is  includes cylinder air charge temperature. 
     
     
       4. A method according to  claim 1 , wherein the vehicle operational states are both engine revolutions per minute and cylinder air charge temperature. 
     
     
       5. A method according to  claim 1 , further including the step of filtering the calculated engine coolant temperature so as to prevent inaccurate display readings resulting from sudden changes in vehicle operational states, the filter step performed prior to the step of generating a signal. 
     
     
       6. A method according to  claim 5 , further including the step of recording  determining the difference between the measured cylinder head temperature and the filtered engine coolant temperature and recording said difference. 
     
     
       7. A method according to  claim 6 , further including the step of storing the recorded difference in keep alive memory. 
     
     
       8. A method according to  claim 7 , further including the steps of:
 decaying the difference between the measured cylinder head temperature and the filtered engine coolant temperature as an exponential function of soak time upon vehicle startup;  
 generating an initial, startup signal by subtracting the measured cylinder head temperature from the last recorded difference stored in keep alive memory; and  
 sending an initial, startup signal to the display.  
 
     
     
       9. A method of inferring engine coolant temperature in cylinder head temperature sensor equipped vehicles comprising the steps of:
 measuring the cylinder head temperature;  
 calculating the engine coolant temperature from the measured cylinder head temperature as a function of engine revolutions per minute and cylinder air charge temperature;  
 generating a signal for the calculated engine coolant temperature; and  
 sending the generated signal to a display.  
 
     
     
       10. A method according to  claim 9 , further including the step of filtering the calculated engine coolant temperature so as to prevent inaccurate display readings resulting from sudden changes in revolutions per minute and air charge temperature, the filtering step performed prior to the step of generating a signal. 
     
     
       11. A method according to  claim 10 , further including the step of recording  determining the difference between the measured cylinder head temperature and the filtered engine coolant temperature and recording said difference. 
     
     
       12. A method according to  claim 11 , further including the step of storing the recorded difference in keep alive memory. 
     
     
       13. A method according to  claim 12 , further including the steps of:
 decaying the difference between the measured cylinder head temperature and the filtered engine coolant temperature as an exponential function of soak time upon vehicle startup;  
 generating an initial, startup signal by subtracting the measured cylinder head temperature from the last recorded difference stored in keep alive memory; and  
 sending an initial, startup signal to the display.  
 
     
     
       14. A system for inferring engine coolant temperature in cylinder head temperature sensor equipped vehicles comprising:
 a cylinder head temperature sensor; and  
 a controller for calculating the engine coolant temperature from the measured cylinder head temperature as a function of engine revolutions per minute and cylinder air charge temperature, wherein the controller generates a signal for the calculated engine coolant temperature and sends the generated signal to a display.  
 
     
     
       15. A system according to  claim 14 , wherein the controller further filters the calculated engine coolant temperature so as to prevent inaccurate display readings resulting from sudden changes in revolutions per minute and air charge temperature, the filtering performed prior to generation of the signal. 
     
     
       16. A system according to  claim 15 , wherein the controller further records  determines the difference between the measured cylinder head temperature and the filtered engine coolant temperature and records said difference. 
     
     
       17. A system according to  claim 16 , wherein the controller further stores the recorded differences in keep alive memory. 
     
     
       18. A system according to  claim 17 , wherein the controller further:
 decays the difference between the measured cylinder head temperature and the filtered engine coolant temperature as an exponential function of soak time if determined that the cylinder head temperature measurement was taken at vehicle startup;  
 generates an initial, startup signal by subtracting the measured cylinder head temperature from the last recorded difference stored in keep alive memory; and  
 sends an initial, startup signal to the display.  
 
     
     
       19. The method according to  claim 1 , further comprising the step of sending the generated signal to a display.  
     
     
       20. A method of operating a motor vehicle having an internal combustion engine, comprising:
   measuring a cylinder head temperature;        inferring an engine coolant temperature from the measured cylinder head temperature; and        generating a signal for the inferred engine coolant temperature.      
     
     
       21. The method according to  claim 20 , further comprising sending the generated signal to a display.  
     
     
       22. The method according to  claim 21 , further including the step of filtering the inferred engine coolant temperature so as to prevent inaccurate display readings resulting from sudden changes in vehicle operational states, the filter step performed prior to the step of generating a signal.  
     
     
       23. The method according to  claim 22 , further including the step of determining the difference between the measured cylinder head temperature and the filtered engine coolant temperature and recording said difference.  
     
     
       24. A method according to  claim 23 , further including the step of storing the recorded difference in keep alive memory.  
     
     
       25. A method according to  claim 24 , further including the steps of:
   decaying the difference between the measured cylinder head temperature and the filtered engine coolant temperature as an exponential function of soak time upon vehicle startup;        generating an initial, startup signal by subtracting the measured cylinder head temperature from the last recorded difference stored in keep alive memory; and        sending an initial, startup signal to the display.