Anti-dieseling control

Claim 1

For use with an engine having a primary combustion zone and a selectively controllable spark ignition system which can be deenergized for shutting down said engine, the combination comprising: a. an air-fuel induction means for supplying a combustible mixture to said engine, b. a duct for supplying fresh air to said mixture, c. a valve for controlling the admission of fresh air to said duct and having a housing extending across said duct and a valve member slidable in said housing for closing off said duct, d. means for operating said valve between open and closed positions of said duct, said means normally biasing said member to a closed position and having a solenoid actuator responsive to engine shut down for overcoming said bias to move said member to an open position, said operating means providing an electrical circuit for said actuator which is responsive to selective de-energization of said spark ignition system to open said valve and delay completion of said de-energization to permit ignition of said mixture for a predetermined period, said circuit being responsive to normal energization of said spark ignition system to open said circuit, and e. a catalytic converter having material for sustaining combustion at a predetermined temperature level, said operating means being effective to continue combustion of said mixture in said primary zone after engine shut-down in a manner to prevent uncombusted mixtures from reaching said catalytic converter that can flamingly combust in said converter at said predetermined temperature level.