Apparatus for detecting concentration of vapor fuel in lean-burn internal combustion engine, and applied apparatus thereof

摘要

An apparatus for detecting a concentration of a vapor fuel in a lean-burn internal combustion engine includes a module for performing purge concentration learning when in a lean-burn where an air/fuel ratio sensor does not sufficiently work. When detecting the concentration of the vapor fuel during a lean-burn operation of the internal combustion engine, the internal combustion engine is switched over to a homogeneous combustion operation from a lean-burn operation, and the concentration of the vapor fuel is detected under the homogeneous combustion operation. Alternatively, the combustion is switched over to the homogeneous combustion when in a rich spike and when ensuring a brake negative pressure, and hence the concentration of the vapor fuel is detected by utilizing this timing. The thus detected and learned concentration of the vapor fuel is utilized for the purge control when in the lean-burn.