Patent ID: 6155227
Filing Date: 2000-12-05
Classification: F02D,Y02T

Abstract:
A control apparatus for a direct injection engine, including an air intake amount measuring means for measuring the amount Qa of intake air taken into each cylinder, an engine rotational speed measuring means for measuring a rotational speed Ne of an engine, a base fuel injection amount calculating means for calculating a base fuel injection pulse width Tp for each cylinder by multiplying the value (Qa/Ne) of said air intake amount Qa divided by said rotational speed Ne by a coefficient such that an air-to-fuel ratio (A/F) of a fuel charge in said cylinder is a stoichiometric ratio (A/F=14.7), a lean charge injection amount calculating means for calculating a lean charge injection pulse width in a lean burn by multiplying said base fuel injection pulse width Tp by an equivalence ratio of said stoichiometric A/F of 14.7 to a lean charge A/F corresponding to said lean charge injection pulse, said control apparatus comprising:burn mode determining means for determining a stoichiometric burn mode or a lean burn mode, and a stratified charge burn mode or a homogeneous charge burn mode;target A/F calculating means for calculating a target A/F according to an operational point of said engine;a phase lag filter for changing the phase of said calculated target A/F;first target A/F modifying means for modifying said target A/F whose phase is delayed, so that an unstable burn region is avoided;second target A/F modifying means for further modifying said modified target A/F during a transitional period when the operation is switched so as to avoid said unstable burn region; andtarget A/F selecting means for selecting one of said modified A/F modified by said first target A/F modifying means and said target A/F modified by said second A/F modifying means.