Split type internal combustion engine

Claim 1

An internal combustion engine comprising: (a) first and second cylinder units each including at least one cylinder; (b) a control circuit responsive to engine load for supplying a mixture of an optimum air/fuel ratio to said first and second cylinder units and for terminating the supply of the mixture to said second cylinder unit when the engine load is below a given value; (c) an exhaust system having therein a catalytic converter for removing pollutants from the exhaust gases flowing therethrough from said cylinders; and (d) an emergency circuit responsive to an increase in the temperature of said catalytic converter for forcing said control circuit to lean out the air/fuel ratio, said emergency circuit comprising: a first comparator for comparing the temperature of said catalytic converter with a first reference value and providing a first command signal when the former is higher than the latter, said first comparator adapted to decrease the first reference value to a given level upon the occurrence of the first command signal; a second comparator for comparing the temperature of said catalytic converter with a second reference value higher than the first reference value and providing a second command signal when the former is higher than the latter, said second comparator adapted to decrease the second reference value to a given level upon the occurrence of the second command signal; and said control circuit being responsive to the first command signal for leaning out the air/fuel ratio to a first predetermined level and terminating the supply of the mixture to said second cylinder unit, said control circuit being responsive to the second command signal for leaning out the air/fuel ratio to a second predetermined level leaner than the first predetermined level.