Air-fuel ratio control system for internal combustion engine
AssigneeNippondenso Co., Ltd.
InventorsYukihiro Yamashita, Kenji Ikuta, Shigenori Isomura
Life of this patent
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Abstract
In an air-fuel ratio control system for an internal combustion engine, a target air-fuel ratio is set on a side opposite to a direction of deviation of a monitored upstream side air-fuel ratio in such a manner as to counterbalance or offset the deviation of the upstream side air-fuel ratio. The deviation of the upstream side air-fuel ratio may be derived in the form of an mount of a particular component adsorbed in a catalytic converter. A learned value may be used to correct the monitored upstream side air-fuel ratio. Further, a monitored downstream side air-fuel ratio may be used to monitor the setting of the target air-fuel ratio.
Claims12
An air-fuel ratio control system for an internal combustion engine, comprising:
- air-fuel ratio detecting means, provided upstream of a catalytic converter in an exhaust passage of the engine, for sequentially detecting air-fuel ratios of an air-fuel mixture based on exhaust gas upstream of the catalytic converter;
- deviation condition determining means for integrating deviations of the detected air-fuel ratios with respect to a stoichiometric air-fuel ratio to derive a sum of the deviations of the detected air-fuel ratios when a given condition is satisfied;
- target air-fuel ratio setting means, based on said sum of the deviations derived by said deviation condition determining means, for setting a target air-fuel ratio on a side opposite to a direction of said sum of the deviations in such a manner as to counterbalance said sum of the deviations, said target air-fuel ratio setting means restoring said target air-fuel ratio to a value before said setting when said sum of the deviations is counterbalanced to a given extent;
- and
- fuel injection amount adjusting means for adjusting a fuel injection amount of a fuel injection valve based on the target air-fuel ratio which is set by said target air-fuel ratio setting means.
An air-fuel ratio control system for an internal combustion engine, comprising:
- air-fuel ratio detecting means, provided upstream of a catalytic converter in an exhaust passage of the engine, for sequentially detecting air-fuel ratios of an air-fuel mixture based on exhaust gas upstream of the catalytic converter;
- deviation condition determining means for integrating deviations of the detected air-fuel ratios with respect to a stoichiometric air-fuel ratio to derive a sum of the deviations of the detected air-fuel ratios and for determining whether said sum of the deviations exceeds a preset rich-side limit value or a preset lean-side limit value;
- target air-fuel ratio setting means for setting a target air-fuel ratio to a lean-side target value which is leaner than the stoichiometric air-fuel ratio when said sum of the deviations exceeds said rich-side limit value and to a rich-side target value which is richer than the stoichiometric air-fuel ratio when said sum of the deviations exceeds said lean-side limit value;
- and
- fuel injection amount adjusting means for adjusting a fuel injection amount of a fuel injection valve based on the target air-fuel ratio which is set by said target air-fuel setting means.
An air-fuel ratio control system for an internal combustion engine, comprising:
- downstream-side air-fuel ratio detecting means, provided downstream of a catalytic converter in an exhaust passage of the engine, for sequentially detecting air-fuel ratios of an air-fuel mixture based on exhaust gas having passed through said catalytic converter;
- target air-fuel ratio setting means for determining a deviation direction of the detected downstream-side air-fuel ratio with respect to a stoichiometric air-fuel ratio, and for setting a target air-fuel ratio on a side opposite to said deviation direction across the stoichiometric air-fuel ratio so as to counterbalance a deviation of said detected downstream-side air-fuel ratio with respect to the stoichiometric air-fuel ratio, said target air-fuel ratio setting means restoring said target air-fuel ratio to a value before said setting when said deviation of the detected downstream-side air-fuel ratio is counterbalanced to a given extent;
- and
- fuel injection amount adjusting means for adjusting a fuel injection amount of a fuel injection valve based on the target air-fuel ratio which is set by said target air-fuel ratio setting means.
Dependencies are inferred from the claim text.