Internal combustion engine

Claim 1

An internal combustion engine comprising: (a) a plurality of cylinders split into first and second groups; (b) an intake passage divided into first and second branches for supplying air to said first and second groups of cylinders, respectively, said second intake passage branch provided near its inlet with a stop valve normally open to allow the flow of air into said second group of cylinders; (c) an exhaust passage divided by a partition into first and second branches leading from said first and second groups of cylinders, respectively; (d) an EGR passage having its one end opening into said second exhaust passage branch and the other end opening into said second intake passage branch downstream of said stop valve, said EGR passage having therein an EGR valve normally closed to interrupt recirculation of exhaust gases into said second intake passage branch; (e) an exhaust gas sensor provided in a through-hole formed in said partition at a position downstream of said one end of said EGR passage for monitoring one content of the engine exhaust to provide a signal indicative of the air/fuel ratio at which said engine is operating; (f) split engine control means responsive to engine loads for cutting off the supply of fuel to said second group of cylinders, closing said stop valve, and opening said EGR valve when the engine load is below a predetermined value; and (g) said second exhaust passage branch has a volume, upstream of said one end of said EGR passage, larger than the stroke volume of said second group of cylinders.