Method and apparatus for an optimized fuel control based on outlet oxygen signal to reduce vehicle missions

Abstract

A control system and method for optimizing fuel control in an internal combustion engine utilizes a signal from an oxygen sensor disposed in an exhaust downstream of a catalytic converter. An air/fuel mixture introduced into the engine is compensated based on the signal exceeding predetermined enabling thresholds. The predetermined rich or lean condition enable threshold represents an oxygen content so less or greater than desired that the normal closed loop control including regular secondary fuel trim is not sufficient enough to bring the outlet oxygen sensor signal back to the desired window quickly. A reduced or increased amount of fuel is introduced into the engine based on the signal exceeding the predetermined rich or lean enable threshold respectively.

1 . A control system for optimizing fuel control in an internal combustion engine, comprising: 
 an exhaust connected to said engine and having a catalytic converter disposed therein;    an oxygen sensor disposed in said exhaust downstream of said catalytic converter that generates an oxygen signal; and    a controller that communicates with said oxygen sensor and that modifies an air/fuel mixture introduced into said engine based on said oxygen signal from said oxygen sensor.    
   
   
       2 . The control system of  claim 1  wherein said controller compares said signal to a predetermined lean condition enable threshold that represents an oxygen content that is greater than desired, and wherein said controller introduces an increased amount of fuel into said engine based on said signal dropping below said predetermined lean condition enable threshold.  
   
   
       3 . The control system of  claim 1  wherein said controller compares said signal to a predetermined rich condition enable threshold that represents an oxygen content that is less than desired, and wherein said controller introduces a reduced amount of fuel into said engine based on said signal exceeding said predetermined rich condition enable threshold.  
   
   
       4 . The control system of  claim 2  wherein said controller compares said signal to a predetermined lean condition disable threshold that represents an oxygen content that is greater than a desired level, but appropriate to return to normal closed loop fueling, and wherein said controller returns fuel delivery to a normal operation based on said signal satisfying said lean condition disable threshold.  
   
   
       5 . The control system of  claim 3  wherein said controller compares said signal to a predetermined rich condition disable threshold that represents an oxygen content that is less than a desired level, but appropriate to return to normal closed loop fueling, and wherein said controller returns fuel delivery to a normal operation based on said signal satisfying said rich condition disable threshold.  
   
   
       6 . The control system of  claim 2  wherein said controller initiates an accumulated engine airflow variable and concludes introducing increased amounts of fuel to said engine based on said accumulated engine airflow reaching a predetermined condition.  
   
   
       7 . The control system of  claim 3  wherein said controller initiates an accumulated engine airflow variable and concludes introducing reduced amounts of fuel to said engine based on said accumulated engine airflow reaching a predetermined condition.  
   
   
       8 . A method for optimizing fuel control in an internal combustion engine, comprising: 
 utilizing a signal from an oxygen sensor disposed in an exhaust downstream of a catalytic converter;    determining whether said signal exceeds predetermined thresholds;    compensating an air/fuel mixture introduced into the engine based on said signal exceeding said predetermined thresholds.    
   
   
       9 . The method of  claim 8  wherein determining if said signal exceeds predetermined thresholds comprises: 
 comparing said signal to a predetermined lean condition enable threshold that represents an oxygen content that is greater than desired; and    introducing an increased amount of fuel into said engine based on said signal dropping below said predetermined lean condition enable threshold.    
   
   
       10 . The method of  claim 8  wherein determining if said signal exceeds predetermined thresholds comprises: 
 comparing said signal to a predetermined rich condition enable threshold that represents an oxygen content less than desired; and    introducing a reduced amount of fuel into said engine based on said signal exceeding said predetermined rich condition enable threshold.    
   
   
       11 . The method of  claim 9 , further comprising: 
 comparing said signal to a predetermined lean condition disable threshold that represents an oxygen content greater than a desired level, but appropriate for the return to normal closed loop fueling; and    returning fuel delivery to a normal operation based on said signal satisfying said lean condition disable threshold.    
   
   
       12 . The method of  claim 10 , further comprising: 
 comparing said signal to a predetermined rich condition disable threshold that represents an oxygen content less than a desired level, but appropriate for the return to normal closed loop fueling; and    returning fuel delivery to a normal operation based on said signal satisfying said rich condition disable threshold.    
   
   
       13 . The method of  claim 9 , wherein introducing an increased amount of fuel comprises introducing an increased amount of fuel into said engine for a predetermined maximum accumulated airflow.  
   
   
       14 . The method of  claim 10 , wherein introducing a reduced amount of fuel further comprises introducing a reduced amount of fuel into said engine for a predetermined maximum accumulated airflow.  
   
   
       15 . A method for optimizing fuel control in an internal combustion engine comprising: 
 determining whether said engine is operating in closed loop control;    utilizing a signal from an oxygen sensor disposed in an exhaust system downstream of a catalytic converter;    determining if said signal exceeds predetermined thresholds; and    introducing a modified amount of fuel into said engine based on said signal exceeding said predetermined thresholds.    
   
   
       16 . The method of  claim 15  wherein determining if said engine is meeting closed loop control conditions further comprises: 
 determining whether diagnostic trouble codes are inactive; and    determining whether said oxygen sensor has reached operating temperature and been ready for use; and    determining whether other open loop fueling or intrusive diagnostic modes are inactive.    
   
   
       17 . The method of  claim 15  wherein determining if said signal exceeds predetermined thresholds comprises: 
 comparing said signal to a predetermined lean condition enable threshold that represents an oxygen content greater than desired; and    introducing an increased amount of fuel into said engine based on said signal below said predetermined lean condition enable threshold.    
   
   
       18 . The method of  claim 15  wherein determining if said signal exceeds predetermined thresholds comprises: 
 comparing said signal to a predetermined rich condition enable threshold that represents an oxygen content less than desired; and    introducing a reduced amount of fuel into said engine based on said signal above said predetermined rich condition enable threshold.    
   
   
       19 . The method of  claim 17 , further comprising: 
 comparing said signal to a predetermined lean condition disable threshold that represents an oxygen content greater than a desired level, but appropriate for the return to normal closed loop fueling; and    returning fuel delivery to a normal operation based on said signal satisfying said lean condition disable threshold.    
   
   
       20 . The method of  claim 18 , further comprising: 
 comparing said signal to a predetermined rich condition disable threshold that represents an oxygen content less than a desired level, but appropriate for the return to normal closed loop fueling; and    returning fuel delivery to a normal operation based on said signal satisfying said rich condition disable threshold.