Exhaust emission control systems and devices

Claim 1

In combination in an internal combustion engine power plant having a combustion chamber, exhaust manifold, and an exhaust passage for exhaust gas flow from said exhaust manifold to the atmosphere: a catalytic converter coupled in series with said exhaust passage effective to cause reaction of exhaust gas constituents flowing therethrough when the temperature of said catalytic converter is above a predetermined temperature level to thereby prevent emission of said constituents to the atmosphere; an exhaust gas afterburner coupled in series with said exhaust passage downstream from said catalytic converter; means coupled to said afterburner for heating exhaust gas in said exhaust passage upstream from said catalytic converter to a temperature level greater than said predetermined temperature; and, said means coupled to said afterburner comprising; temperature sensing means responsive to the temperature of exhaust gas in said exhaust passage upstream from said catalytic converter; and, duct means responsive to said temperature sensing means for coupling said afterburner in said exhaust passage upstream from said catalytic converter when the temperature sensed by said temperature sensing means is below said predetermined temperature, said duct means including means for reversing the exhaust flow path through said exhaust gas afterburner and said catalytic converter; and, means for switching said afterburner to a lower temperature when the temperature sensed is below said predetermined temperature and switching said afterburner to a higher temperature in response to detection of exhaust gas temperature above said predetermined temperature.