Abstract: A fuel injection control system and method for an internal combustion engine and an engine control unit, for accurately determining a fuel injection period and for performing accurate and optimum control of the actual fuel injection amount. An amount of fuel demanded by the engine is determined according to the detected operating conditions of the engine. An amount of fuel deposited on walls downstream of the fuel injection valve is determined according to the detected operating conditions. A net amount of fuel to be injected from the fuel injection valve is determined based on the determined demand amount of fuel and the determined deposited amount of fuel. Pressure of fuel to be injected from the fuel injection valve is determined. The fuel injection period is determined by correcting the determined net amount of fuel according to the determined pressure of fuel.

Abstract: A valve timing controller for use in a direct injection type internal combustion engine is provided for enabling a valve timing to be appropriately set in accordance with a load on the engine even in a stratified combustion mode. The internal combustion engine has a valve timing changing mechanism for changing a valve timing of at least one of an intake valve and an exhaust valve so that it is operated in a combustion mode switched between a uniform combustion mode in which a fuel is injected into a cylinder during an intake stroke and a stratified combustion mode in which a fuel is injected into a cylinder in a compression stroke. The valve timing controller comprises a required torque determining unit for determining a required torque outputted by the internal combustion engine based on the engine rotational speed and accelerator pedal opening, and a valve timing determining unit for determining the valve timing in accordance with the required torque and the engine rotational speed.

Abstract: A control system for a direct injection spark ignition engine connected to an automatic transmission that modifies engine power in accordance with a selected one of shift programs (a normal mode for improved fuel economy and a power mode for improved performance). A torque required by the engine is determined based on the detected engine speed and the engine load in accordance with characteristics corresponding to the selected shift program. And, an engine operation mode is determined to one of three modes including a stoichiometric air/fuel ratio operation mode in which a desired air/fuel ratio is set to a stoichiometric air/fuel ratio and two lean-bum operations mode in which the desired air/fuel ratio is set to be leaner than the stoichiometric air/fuel ratio. The desired air/fuel ratio is used to correct the fuel injection amount to be supplied to the engine.

Abstract: In a direct injection spark ignition engine which is operable in three operation modes including a stoichiometric air/fuel ratio operation mode, a pre-mixture combustion mode and a stratified combustion operation mode which are different in the desired air/fuel ratio and a single air/fuel ratio sensor installed downstream of the exhaust manifold, the sensor output is successively sampled and one from among the sampled data is selected based on the engine speed and engine load and selected one of the operation modes such that the air/fuel ratio at each cylinder can be accurately estimated for the selected operation mode under the engine operating conditions.

Abstract: There is disclosed a fuel injection control system and method for an internal combustion engine as well as an engine control unit, which are capable of accurately determining a fuel injection period such fuel pressure and fuel deposition are reflected therein, thereby performing accurate and optimum control of the actual fuel injection amount. Operating conditions of the engine are detected. An amount of fuel demanded by the engine is determined according to the detected operating conditions of the engine. An amount of fuel deposited on walls downstream of the fuel injection valve, out of an amount of fuel injected from the fuel injection valve, is determined according to the detected operating conditions. A net amount of fuel to be injected from the fuel injection valve is determined based on the determined demanded amount of fuel and the determined deposited amount of fuel. Pressure of fuel to be injected from the fuel injection valve is determined.

Abstract: An exhaust gas purification apparatus for an internal combustion engine capable of lean operation has an Ir-containing selectively reducing catalyst and an NOx adsorptive catalyst. The Ir-containing selectively reducing catalyst in which iridium is an active species thereof and NOx is selectively reduced in a lean atmosphere by HC as a reducer is disposed in an exhaust system of the internal combustion engine. The Ir-containing selectively reducing catalyst is disposed on an upstream side of the exhaust system. The NOx adsorptive catalyst adsorbs NOx in the lean atmosphere and reduce the adsorbed NOx at a theoretical air-fuel ratio or at a rich air-fuel ratio. The NOx adsorptive catalyst is disposed on a downstream side of the exhaust system.

Abstract: In a direct injection spark ignition engine which is operable in lean-burn operation modes including a pre-mixture combustion mode and a stratified combustion operation mode and a stoichiometric air/fuel ratio operation mode, which are different in the desired air/fuel ratio. The degradation of combustion state is detected through misfire detection and if it is determined to be degraded, the desired air/fuel ratio, the EGR flow rate and the ignition timing are changed when the engine is operated in the stratified combustion operation mode, while the desired air/fuel ratio, the EGR flow rate and the purge flow rate are changed when the engine is operated in the pre-mixture combustion operation mode, thereby ensuring to suppress the combustion state degradation effectively.

Abstract: A control system for a direct injection spark ignition engine connected to an automatic transmission that modifies engine power in accordance with a selected one of shift programs (a normal mode for improved fuel economy and a power mode for improved performance). A torque required by the engine is determined based on the detected engine speed and the engine load in accordance with characteristics corresponding to the selected shift program. And, an engine operation mode is determined to one of three modes including a stoichiometric air/fuel ratio operation mode in which a desired air/fuel ratio is set to a stoichiometric air/fuel ratio and two lean-bum operations mode in which the desired air/fuel ratio is set to be leaner than the stoichiometric air/fuel ratio. The desired air/fuel ratio is used to correct the fuel injection amount to be supplied to the engine.

Abstract: A valve timing controller for use in a direct injection type internal combustion engine is provided for enabling a valve timing to be appropriately set in accordance with a load on the engine even in a stratified combustion mode. The internal combustion engine has a valve timing changing mechanism for changing a valve timing of at least one of an intake valve and an exhaust valve so that it is operated in a combustion mode switched between a uniform combustion mode in which a fuel is injected into a cylinder during an intake stroke and a stratified combustion mode in which a fuel is injected into a cylinder in a compression stroke. The valve timing controller comprises a required torque determining unit for determining a required torque outputted by the internal combustion engine based on the engine rotational speed and accelerator pedal opening, and a valve timing determining unit for determining the valve timing in accordance with the required torque and the engine rotational speed.

Abstract: In a direct injection spark ignition engine which is operable in lean-burn operation modes including a pre-mixture combustion mode and a stratified combustion operation mode and a stoichiometric air/fuel ratio operation mode, which are different in the desired air/fuel ratio. The degradation of combustion state is detected through misfire detection and if it is determined to be degraded, the desired air/fuel ratio, the EGR flow rate and the ignition timing are changed when the engine is operated in the stratified combustion operation mode, while the desired air/fuel ratio, the EGR flow rate and the purge flow rate are changed when the engine is operated in the pre-mixture combustion operation mode, thereby ensuring to suppress the combustion state degradation effectively.

Abstract: In a direct injection spark ignition engine which is operable in three operation modes including a stoichiometric air/fuel ratio operation mode, a pre-mixture combustion mode and a stratified combustion operation mode which are different in the desired air/fuel ratio and a single air/fuel ratio sensor installed downstream of the exhaust manifold, the sensor output is successively sampled and one from among the sampled data is selected based on the engine speed and engine load and selected one of the operation modes such that the air/fuel ratio at each cylinder can be accurately estimated for the selected operation mode under the engine operating conditions.

Abstract: A system for controlling a temperature of an air-fuel ratio sensor heater of an direct injection spark ignition engine which is operated at an ultra-lean burn combustion or at a pre-mixture charged combustion. In the system, the temperature of the air-fuel ratio sensor is estimated and the supply of current to the heater is determined in terms of a duty ratio in PWM based on the estimated temperature of the air-fuel ratio sensor and is increased when the engine is determined to be operated at the ultra-lean burn combustion. The duty ratio is increased by an augmentative on-time which is determined based on a parameter such as a desired torque, an engine speed and load, or a vehicle speed. The supply of current is also increased when the operation of the EGR is in progress.

Abstract: There is provided a catalyst deterioration-detecting system for an internal combustion engine having at least one catalyst arranged in the exhaust passage, for purifying noxious components present in exhaust gases emitted from the engine, and an exhaust gas component concentration sensor arranged in the exhaust passage at a location downstream of the catalyst, for detecting concentration of a specific component in the exhaust gases. An ECU of the system controls the ignition timing of the engine, and detects the degree of deterioration of the catalyst, based on an output value from the exhaust gas component concentration sensor. The ignition timing of the engine is retarded in dependence on the detected degree of deterioration of the catalyst.

Abstract: An air-fuel ratio control system for an internal combustion engine includes a LAF sensor and an O2 sensor arranged in an exhaust pipe at respective locations upstream and downstream of a catalytic converter. A desired air-fuel ratio coefficient used in calculating an amount of fuel supplied to the engine is calculated based on operating conditions of the engine, and corrected based on output from the O2 sensor. The air-fuel ratio of a mixture supplied to the engine is feedback-controlled to a stoichiometric air-fuel ratio based on the corrected desired air-fuel ratio coefficient. When the output from the O2 sensor falls within a predetermined range, the desired air-fuel ratio coefficient is not corrected, but held at an immediately preceding value thereof.

Abstract: A control system according to one aspect calculates a ratio of an actual amount of fuel supplied to the combustion chamber to the desired amount of fuel to be supplied to the combustion chamber, by taking into account at least an amount of evaporative fuel supplied to the combustion chamber, and sets the rate of change of the air-fuel ratio correction coefficient based on this ratio of the actual amount to the desired amount. A control system according to another aspect of the invention calculates an injected fuel ratio of an amount of fuel injected to an amount of total fuel to be supplied to the combustion chamber, and controls the ignition timing based on the injected fuel ratio and depending on operating conditions of the engine.

Abstract: An air-fuel ratio control system for an internal combustion engine includes a LAF sensor and an O2 sensor arranged in an exhaust pipe at respective locations upstream and downstream of a catalytic converter. A desired air-fuel ratio coefficient used in calculating an amount of fuel supplied to the engine is calculated based on operating conditions of the engine, and corrected based on output from the O2 sensor. The air-fuel ratio of a mixture supplied to the engine is feedback-controlled to a stoichiometric air-fuel ratio based on the corrected desired air-fuel ratio coefficient. When the output from the O2 sensor falls within a predetermined range, the desired air-fuel ratio coefficient is not corrected, but held at an immediately preceding value thereof.

Abstract: A control system for an internal combustion engine according to one aspect of the invention calculates a total amount of evaporative fuel purged from a canister based on dynamic characteristics and concentration of purged gas. The system calculates an amount of evaporative fuel supplied to the combustion chamber of the engine based on the total amount of evaporative fuel and depending on dynamic characteristics of the purged gas. Then, the system determines a required amount of fuel to be injected by a fuel injection valve based on the amount of evaporative fuel supplied to the combustion chamber.

Abstract: A control system for controlling operation of an internal combustion engine detects a selected one of two exhaust modes: a first exhaust mode in which exhaust gases are guided through a first catalytic converter upstream of a second catalytic converter, and a second exhaust mode in which exhaust gases are guided through a bypass passage bypassing the first catalytic converter. A control mode is determined according to the selected one of the two exhaust modes, in which the operation of the engine is to be controlled by the control system.