Clean air system

Abstract

The present invention provides a method for controlling exhaust gas emissions including platinum, wherein exhaust gas is brought into contact with an emissions control catalyst and the oxygen content of the exhaust gas is controlled in order to maintain fuel rich stoichiometry close to the stoichiometric value.

1 . A method for controlling exhaust gas emissions including platinum, comprising: 
 a) contacting the exhaust gas with an emissions control catalyst; and    b) controlling the oxygen content of the exhaust gas to maintain fuel rich stoichiometry close to the stoichiometric value.    
   
   
       2 . The method of  claim 1  wherein the catalyst is a three way catalyst.  
   
   
       3 . The method of  claim 1  wherein the catalyst is an oxidation catalyst.  
   
   
       4 . The method of  claim 1  wherein a universal oxygen sensor is used to measure exhaust gas stoichiometry.  
   
   
       5 . The method of  claim 4  wherein the measured exhaust gas stoichiometry is fed real time to a fuel flow control computer.  
   
   
       6 . The method of  claim 5  wherein the fuel control computer is programmed to maintain a constant fuel-air stoichiometry in transient operation.  
   
   
       7 . The method of  claim 6  wherein sufficient oxygen is present to consume all but between about ten and about two hundred ppm of the fuel values present.  
   
   
       8 . A method for operating an automotive engine comprising: 
 a) controlling fuel flow in relation to air flow;    b) measuring exhaust gas stoichiometry using a universal oxygen sensor; and    c) adjusting fuel flow to maintain exhaust gas stoichiometry slightly on the rich side of stoichiometric.