To restrain variation of an air-fuel ratio of each of cylinders, in an engine wherein a suction air amount is controlled by changing an open valve characteristic value.
A valve lift amount and a working angle (vale opening period) of an intake valve 2 of the engine 1 is changed during operation using a variable valve mechanism 9, and an amount of intake air filling each of the cylinder is controlled. The valve lift amount and the working angle are changed by delaying an ignition timing of each of the cylinders at idle operating of the engine, to measure the air-fuel ratio of each of the cylinders by a single air-fuel ratio sensor 57 arranged to an exhaust passage, and air-fuel ratio correction coefficient for correcting the variation of the air-fuel ratio is calculated. At an operation other than the idle operation, the air-fuel ratio correction coefficient found at the idle operation is corrected in accordance with an engine operation condition(engine speed, load, and temperature), whereby a fuel injection amount of each of the cylinders is corrected without actually measuring the variation of the air-fuel ratio of each of the cylinders by the air-fuel ratio sensor.
COPYRIGHT: (C)2004,JPO
Toshiaki Asada
| JP10054279A |
Jun Tsuruta
Tetsuro Shimada
Masaya Nishiyama