Patent ID: 7454901
Filing Date: 2008-11-25
Classification: F01N,F02D

Abstract:
1. An exhaust system for exhausting gas from a plurality of cylinders of an engine, the exhaust system comprising: a plurality of first exhaust pipes corresponding in number to the plurality of cylinders, into which the gas exhausted from the plurality of cylinders flows, respectively; a first catalyst device having a first catalyst that cleanses the gas introduced from the plurality of first exhaust pipes; a first assembler arranged to assemble and couple first ends of the plurality of first exhaust pipes to the first catalyst device; a plurality of first inflow portions provided at the first assembler that allow the gas exhausted from the plurality of first exhaust pipes to flow into the first catalyst device; a first detector provided in only one of the plurality of first exhaust pipes or only one of the plurality of first inflow portions and arranged to detect the information about an oxygen concentration of the gas exhausted from only a respective one of the plurality of cylinders; and a controller that controls the amounts of fuel injected in the plurality of cylinders, based on the information about the oxygen concentration detected by the first detector; wherein the first assembler is connected to the first catalyst device such that the plurality of first inflow portions are not in communication with each other; the first exhaust pipe or the first inflow portion provided with the first detector is connected to the cylinder in which the amount of injected fuel is the closest to an average of the amounts of fuel injected in the plurality of cylinders; and the controller calculates the air-fuel ratio in the cylinder in which the amount of injected fuel is the closest to the average amount based on the information about the oxygen concentration detected by the first detector, and controls the amounts of fuel injected in the plurality of cylinders based on the difference between the calculated air-fuel ratio and a predetermined target air-fuel ratio.