Abstract: An EGR control system that is capable of controlling the amount of recirculation of high-temperature and low-temperature recirculated gases, with high accuracy, to thereby improve the control accuracy of in-cylinder temperature. An ECU of an ERG control system calculates a fresh intake air ratio, and sets a target value of the fresh intake air ratio. The ECU calculates a feedback correction coefficient for converging the fresh intake air ratio to the target value, with an I-PD control algorithm, and sets an external EGR ratio and an internal EGR ratio. The ECU controls the EGR amount whose ratio is the larger, according to the larger one of the two ratios and the feedback correction coefficient, and controls the EGR amount whose ratio is the smaller, according to the smaller of the ratios and the learned value thereof.

Abstract: In a control system for a compression-ignition engine whose operation is switchable between a compression-ignition operation in which an air-fuel mixture supplied to a combustion chamber auto-ignites to burn owing to compression and a spark-ignition operation in which the air-fuel mixture is ignited to burn by a spark of a spark plug, it is determined whether a predetermined prohibitive condition to prohibit switching from the spark-ignition to the compression-ignition operation is satisfied, and switching from the spark-ignition operation to the compression-ignition operation is prohibited when the predetermined prohibitive condition is satisfied, thereby enabling to avoid premature ignition and misfire and to prevent drivability and fuel consumption performance from being affected therefrom.

Abstract: In a control system for a compression-ignition engine whose operation is switchable between a compression-ignition operation in which an air-fuel mixture supplied to a combustion chamber auto-ignites to burn owing to compression and a spark-ignition operation in which the air-fuel mixture is ignited to burn by a spark of a spark plug, it is determined whether a predetermined permissible condition to permit switching from the spark-ignition to the compression-ignition operation is satisfied, and switching from the spark-ignition operation to the compression-ignition operation is permitted when the predetermined permissible condition is satisfied, thereby enabling to expand the compression-ignition operation utilization region so long as permissible in light of the engine operating condition.

Abstract: There is provided a control system for an internal combustion engine, which is capable of matching an output torque of the engine with a demanded torque excellently when the combustion mode is switched, thereby enhancing drivability. A demanded fuel amount and a demanded torque of the engine are calculated according to detected operating conditions of the engine. A combustion mode is determined to be either the stratified combustion mode or the homogeneous combustion mode according to the demanded torque. A pre-switching demanded fuel injection time period and a pre-switching demanded torque are stored. When the combustion mode is switched, a switching-time demanded fuel amount (limit value) is calculated according to the stored pre-switching demanded fuel injection time period and pre-switching demanded torque, the current demanded torque, and an estimated combustion efficiency parameter.

Abstract: In a vehicle designed so that a driven wheel is driven by uniting an output from an engine and an output from a Rankine cycle system to each other, an accelerator pedal and a throttle valve are connected electrically to each other by a DBW control unit. When an accelerator opening degree (?ap) commanded by a driver is increased, a throttle opening degree (?th) is increased by a correcting amount (??th) more than a value proportional to the accelerator opening degree (?ap), thereby compensating for an output shortage due to a response delay of the output from the Rankine cycle system. When the accelerator opening degree (?ap) commanded by the driver is decreased, the throttle opening degree (?th) is decreased by the correcting amount (??th) more than the value proportional to the accelerator opening degree (?ap), thereby compensating for an output excessiveness due to the response delay of the output from the Rankine cycle system.

Abstract: There is provided a control system for an internal combustion engine, which is capable of matching an output torque of the engine with a demanded torque excellently when the combustion mode is switched, thereby enhancing drivability. A demanded fuel amount and a demanded torque of the engine are calculated according to detected operating conditions of the engine. A combustion mode is determined to be either the stratified combustion mode or the homogeneous combustion mode according to the demanded torque. A pre-switching demanded fuel injection time period and a pre-switching demanded torque are stored. When the combustion mode is switched, a switching-time demanded fuel amount (limit value) is calculated according to the stored pre-switching demanded fuel injection time period and pre-switching demanded torque, the current demanded torque, and an estimated combustion efficiency parameter.

Abstract: A brake negative pressure control apparatus and method, and an engine control unit for an internal combustion engine are provided for ensuring a negative pressure within a brake booster and a stable combustion while avoiding a complicated control. The brake negative pressure control apparatus comprises a negative pressure sensor for detecting a negative pressure within the brake booster, and an ECU for disabling the combustion mode to be set to the stratified combustion when the detected negative pressure is lower than a first predetermined negative pressure. The ECU controls a throttle valve opening in accordance with a target throttle valve opening in a homogeneous combustion mode when the ECU disables the combustion mode to be set to the stratified combustion.

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: In a vehicle designed so that a driven wheel is driven by uniting an output from an engine and an output from a Rankine cycle system to each other, an accelerator pedal and a throttle valve are connected electrically to each other by a DBW control unit. When an accelerator opening degree (&thgr;ap) commanded by a driver is increased, a throttle opening degree (&thgr;th) is increased by a correcting amount (&Dgr;&thgr;th) more than a value proportional to the accelerator opening degree (&thgr;ap), thereby compensating for an output shortage due to a response delay of the output from the Rankine cycle system. When the accelerator opening degree (&thgr;ap) commanded by the driver is decreased, the throttle opening degree (&thgr;th) is decreased by the correcting amount (&Dgr;&thgr;th) more than the value proportional to the accelerator opening degree (&thgr;ap), thereby compensating for an output excessiveness due to the response delay of the output from the Rankine cycle system.

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: There are provided a control system and method and an engine control unit for an internal combustion engine, which are capable of determining an amount of fuel to be injected during a two-stage fuel injection combustion mode and a duration period of this mode such that stable combustion and smooth transition between combustion and smooth transition between combustion modes are ensured. The control system includes an ECU and a crank angle sensor. The ECU calculates a demanded torque PME demanded of the engine, and determines which of the homogenous combustion mode, the stratified combustion mode, and the two-stage fuel injection combustion mode should be selected as the combustion mode of the engine, based on the demanded torque PME. The ECU determines an injection time period ToutD during the compression stroke in two-stage fuel injection combustion mode based on 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: An ignition time controller for an internal combustion engine is provided for setting an ignition time such that it can rapidly converge to an appropriate value in accordance with a change in intake characteristics associated with a change in cam phase in either of a uniform combustion mode and a stratified combustion mode in a direct injection type internal combustion engine having a cam phase changing mechanism.

Abstract: A brake negative pressure control apparatus and method, and an engine control unit for an internal combustion engine are provided for ensuring a negative pressure within a brake booster and a stable combustion while avoiding a complicated control. The brake negative pressure control apparatus and method, and engine control unit are for use with an internal combustion engine of an in-cylinder direct fuel injection type which is configured to set a combustion mode to a stratified combustion or a homogeneous stoichiometric combustion based on a required output in accordance with at least an opening of an accelerator pedal and an operating condition of the internal combustion engine, and is equipped with a brake booster for increasing a braking force of a brake with a negative pressure introduced from an intake pipe.

Abstract: There are provided a control system and method and an engine control unit for an internal combustion engine, which are capable of attaining a high combustion efficiency in both of a homogeneous and a stratified combustion modes, thereby improving drivability and fuel economy, as well as a control system for an internal combustion engine which is capable of ensuring stable combustion in both the modes. In one form of the invention, the control system includes an ECU for controlling ignition timing IG of an in-cylinder fuel injection type engine which is operated while switching the combustion mode between the homogeneous and stratified combustion modes. The ECU determines which of the homogeneous and stratified combustion modes should be selected.

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: There is disclosed a fuel injection control system for an in-cylinder fuel injection internal combustion engine, which is capable of properly determining a fuel injection time period such that the fuel injection time period reflects a fuel pressure and a deposition of fuel, thereby controlling the amount of fuel to be actually injected. Operating conditions of the engine are detected, and a required fuel amount is determined based on the detected operating conditions. At the same time, a deposited-fuel amount, i.e. an amount of fuel deposited in a combustion chamber, is determined based on the detected operating conditions, and the required fuel amount is corrected according to the determined deposited-fuel amount. Further, a fuel pressure of fuel to be injected into the cylinder is detected, and the fuel injection time period is determined by correcting the corrected required fuel amount according to the detected fuel pressure.