Patent ID: 6923149
Filing Date: 2005-08-02
Classification: F01L,F02D,F02M,Y02T

Abstract:
1. A control device for a multicylinder spark-ignition engine of which individual cylinders undergo successive combustion cycles with specific phase delays, wherein the engine is switched depending on its operating conditions between a normal operation mode, in which combustion is produced with the individual cylinders set to work independently of one another, and a special operation mode, in which burned gas discharged from a preceding cylinder which is currently in an exhaust stroke is introduced directly into a following cylinder which is currently in an intake stroke, said control device comprising: a flow path switching unit for switching intake and exhaust flow paths to form a two-cylinder interconnect configuration in the special operation mode such that the burned gas discharged from the preceding cylinder is introduced into the following cylinder through an intercylinder gas channel and an independent cylinder configuration in the normal operation mode such that fresh air is introduced into the individual cylinders; and an air-fuel ratio control unit for controlling the air-fuel ratio in the individual cylinders in such a manner that combustion in the preceding cylinder is produced under lean mixture conditions at an air-fuel ratio larger than the stoichiometric air-fuel ratio by a specific amount by injecting fuel directly into the preceding cylinder and combustion in the following cylinder is produced at an air-fuel ratio approximately equal to the stoichiometric air-fuel ratio by supplying the fuel together with the burned gas of a lean mixture state discharged from the preceding cylinder in the special operation mode; wherein said flow path switching unit switches the intake and exhaust flow paths to the independent cylinder configuration at engine startup to perform combustion control operation in the normal operation mode.