Fuel injection control system for direct injection-spark ignition engine
First Claim
1. A fuel injection control system, for a direct injection-spark ignition type of engine equipped with an injector operative to spray fuel directly into a combustion chamber of the engine, which determines an injection pulse width corresponding to a given quantity of fuel with which the injector is kept open to spray said quantity of fuel, controls the injector to spray fuel through a compression stroke while the engine operates with lower engine loads in an engine operating zone specified for lean stratified charge combustion so that the fuel is stratified around an ignition plug to cause lean stratified charge combustion to, thereby, provide an air-fuel ratio greater than a stoichiometric air-fuel ratio, said fuel injection control system comprising:
- an oxygen sensor operative to monitor the oxygen content of an exhaust gas to detect an air-fuel ratio; and
control means for executing fuel injection feedback control to control said quantity of fuel injection based on said air-fuel ratio detected by said oxygen sensor, causing the injector to spray fuel through a plurality of intake stroke split injections in a specified engine operating zone in which said fuel injection feedback control is performed to maintain at least an approximately stoichiometric air-fuel ratio while the engine operates with lower loads, determining a fuel injection quantity characteristic of the injector with respect to injection pulse width for each said intake stroke split injection based on a value controlled by the fuel injection feedback control during execution of the intake stroke split injection to determine a learning correction value, and making said learning correction value reflect on said control of the quantity of fuel in a minute injection quantity zone specified within said specified engine operating zone for said lean stratified charge combustion.
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Accused Products
Abstract
A fuel injection control system for a direct injection-spark ignition engine determines an injection pulse width corresponding to a given quantity of fuel with which an injector is kept open, controls the injector to spray a given quantity of fuel in a compression stroke while the engine operates in a zone of lower engine loads specified for lean stratified charge combustion so that the fuel is stratified around an ignition plug to cause lean stratified charge combustion so as thereby to provide an air-fuel ratio greater than a stoichiometric air-fuel ratio, executes fuel injection feedback control to control a quantity of fuel injection based on an air-fuel ratio detected by an oxygen sensor, causes the injector to spray a given quantity of fuel through a plurality of intake stroke split injection in a specified engine operating zone in which the fuel injection feedback control is performed to maintain at least a stoichiometric air-fuel ratio while the engine operates with lower loads, learns a fuel injection quantity characteristic of the injector with respect to injection pulse width for each intake stroke split injection based on a value controlled by the fuel injection feedback control during execution of the intake stroke split injection to determine a leaning correction value, and makes the learning correction value reflect on the control of the quantity of fuel in a minute injection zone specified within the specified engine operating zone for the lean stratified charge combustion.
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Citations
15 Claims
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1. A fuel injection control system, for a direct injection-spark ignition type of engine equipped with an injector operative to spray fuel directly into a combustion chamber of the engine, which determines an injection pulse width corresponding to a given quantity of fuel with which the injector is kept open to spray said quantity of fuel, controls the injector to spray fuel through a compression stroke while the engine operates with lower engine loads in an engine operating zone specified for lean stratified charge combustion so that the fuel is stratified around an ignition plug to cause lean stratified charge combustion to, thereby, provide an air-fuel ratio greater than a stoichiometric air-fuel ratio, said fuel injection control system comprising:
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an oxygen sensor operative to monitor the oxygen content of an exhaust gas to detect an air-fuel ratio; and
control means for executing fuel injection feedback control to control said quantity of fuel injection based on said air-fuel ratio detected by said oxygen sensor, causing the injector to spray fuel through a plurality of intake stroke split injections in a specified engine operating zone in which said fuel injection feedback control is performed to maintain at least an approximately stoichiometric air-fuel ratio while the engine operates with lower loads, determining a fuel injection quantity characteristic of the injector with respect to injection pulse width for each said intake stroke split injection based on a value controlled by the fuel injection feedback control during execution of the intake stroke split injection to determine a learning correction value, and making said learning correction value reflect on said control of the quantity of fuel in a minute injection quantity zone specified within said specified engine operating zone for said lean stratified charge combustion. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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Specification