Apparatus and method relating to internal combustion engines utilizing an exhaust gas reactor

In a four-stroke, spark ignition, internal combustion engine adapted to utilize for operating conditions other than deceleration an air/fuel charge which is not richer than stoichiometric derived from a fuel supply means which delivers a fuel/air mixture that is not richer than stoichiometric, said engine being of the type which includes a combustion chamber, induction means for receiving said mixture and introducing said charge to the combustion chamber, an exhaust conduit for removing spent charge from the combustion chamber, an exhaust gas reactor in the exhaust conduit, and a throttle valve controlling flow of air into the induction means, the improvement comprising:

• means for introducing supplementary fuel into said induction means;
• means for introducing supplementary air into said induction means;
• control means responsive to pressure in the induction means characteristic of the closure of the throttle valve at deceleration conditions, said control means operationally effective on the means for supplying supplementary air to cause it to supply supplementary air to the induction means for a predetermined and limited time after said throttle closure;
• and control means responsive to said pressure operationally effective on said means to supply supplementary fuel to the induction means to cause it to supply supplementary fuel after a delay from said closure so long as the said pressure persists.