Patent ID: 6928980

Claim:
A control device for a four-cycle multicylinder spark-ignition engine of which individual cylinders go through successive combustion cycles with specific phase delays, wherein said control device switches the engine according to operating conditions thereof between, a normal operation mode, in which an independent cylinder configuration is formed so that combustion occurs independently in the individual cylinders with fresh air introduced thereinto, and a special operation mode, in which each pair of preceding and following cylinders of which exhaust and intake strokes overlap is connected to form a two-cylinder interconnect configuration in a part-load operating range of the engine so that burned gas discharged from the preceding cylinder which is currently in the exhaust stroke is introduced into the following cylinder which is currently in the intake stroke through an intercylinder gas channel and gas discharged from the following cylinder is led to an exhaust passage, a lean mixture having an air-fuel ratio higher than the stoichiometric air-fuel ratio is combusted in the preceding cylinder, and a mixture produced by supplying fuel to the burned gas having a high air-fuel ratio introduced from the preceding cylinder is combusted in the following cylinder, said control device having a capability to switch the engine between the normal operation mode and the special operation mode via a transitional operation mode in which gas flow paths are connected to form the two-cylinder interconnect configuration and said control device interrupts combustion in the preceding cylinders while producing combustion in the following cylinders by compression ignition.