Abstract: A fourth cylinder is mounted with a cylinder pressure sensor. The injection timing of the fourth cylinder is operated so as to feedback control the ignition timing of the fourth cylinder, which is detected by the cylinder pressure sensor, to a target ignition timing. The ignition timings of the first cylinder to the third cylinder are indirectly controlled by operating the injection timings so as to make output torques produced by combustion in the first cylinder to the third cylinder correspond to an output torque produced by combustion in the fourth cylinder.

Abstract: The internal combustion engine control apparatus includes a calculation function of calculating an energy generation rate of an energy generated by combustion of fuel injected into a combustion chamber of a compression-ignition internal combustion engine, and an ignition detection function of detecting an ignition timing of the fuel in the combustion chamber on the basis of a timing at which the energy generation rate exceeds a first threshold value. When the energy generation rate due to a main injection, which is an object of ignition timing detection by the ignition detection function, exceeds the first threshold value at a plurality of timings, the ignition detection function determines an earliest one of the plurality of the timings as the ignition timing of the main injection.

Abstract: An oxidation catalyst is disposed upstream of a diesel particulate filter (DPF) in an exhaust passage of a diesel engine. An electronic control unit (ECU) operates temperature increasing circuit to combust and eliminate particulate matters deposited on the DPF. The ECU determines execution and stoppage of regeneration of the DPF based on a quantity of the particulate matters deposited on the DPF. The ECU increases an exhaust gas recirculation quantity (EGR quantity) during the regeneration to reduce an intake air quantity from the intake air quantity in a non-regeneration period and to achieve a flow rate of the exhaust gas passing through the DPF suitable for the temperature increase. The ECU corrects a valve opening degree of an EGR control valve based on the sensed intake air quantity to reduce a variation in the exhaust gas flow rate.

Abstract: An abnormality determination device of a cylinder pressure sensor calculates a gain (sensing sensitivity coefficient) and an offset (bias) indicating an output characteristic of the cylinder pressure sensor. The device determines existence or nonexistence of an abnormality in the gain and the offset respectively. When the device determines that the abnormality exists, the device performs failsafe processing set in modes different from each other between the case of the abnormality in the gain and the case of the abnormality in the offset. As the failsafe processing in the case of the abnormality in the gain, the device performs processing for substantially prohibiting usage of a sensor value of the cylinder pressure sensor in control (fuel injection timing control) by using an alternative value (specified value) instead of the sensor value of the cylinder pressure sensor.

Abstract: An exhaust recirculation apparatus is provided to an engine. A high-pressure EGR passage branches from upstream of a turbine of a turbocharger in an exhaust system for recirculating exhaust gas to downstream of a compressor of the turbocharger in an intake system. A high-pressure EGR regulating unit controls exhaust gas through the high-pressure EGR passage. A low-pressure EGR passage branches from downstream of the turbine in the exhaust system for recirculating exhaust gas to upstream of the compressor in the intake system. A low-pressure EGR regulating unit controls exhaust gas through the low-pressure EGR passage. A control unit feedback-controls the high-pressure EGR regulating unit, and open-controls the low-pressure EGR regulating unit when exhaust gas is recirculated through the high-pressure EGR passage and the low-pressure EGR passage. The control unit feedback-controls the low-pressure EGR regulating unit when exhaust gas is recirculated through only the low-pressure EGR passage.

Abstract: In an engine, when it is determined that catalyst, which is held on a filter substrate of a particulate filter, is not in an active state, an ECU executes a fuel injection for mainly obtaining an engine power near a top dead center of a crank. Then, the ECU executes a subsequent fuel injection after lapse of a sufficient injection interval, which does not cause misfiring, to increase the temperature of exhaust gas outputted from the engine. In this way, the temperature of the filter is rapidly increased.

Abstract: An engine control apparatus for a multi-cylinder compression ignition internal combustion engine includes a combustion status sensor and a controller. The combustion status sensor is installed in a selected one of cylinders of the engine. The controller works to sample an output from the combustion status sensor to determine a combustion status parameter and determine injection timings so as to bring the combustion status parameter into agreement with a target value. The controller also corrects the injection timing for at least one of the cylinders in which the combustion status sensor is not installed so that a combustion status parameter of the at least one of the cylinders lies on an advanced side of that of the one of the cylinders in which the combustion status sensor is installed, thereby avoiding the deterioration of quality of combustion of the fuel arising from a shift of the time of the ignition in the retarded direction from a desired time point.

Abstract: A compression ignition internal combustion engine includes injectors, each of which injects fuel into a corresponding cylinder. An ECU determines target ignition timing based on engine operational information and adjusts fuel injection start timing and a fuel injection quantity of each injector based on the target ignition timing. The engine further includes an air/fuel ratio sensor, which senses an oxygen concentration of exhaust gas. The ECU corrects the target ignition timing based on the oxygen concentration, which is sensed with the air/fuel ratio sensor, with reference to a predefined relationship between the oxygen concentration and ignition timing for achieving a generally equal constant torque of the engine.

Abstract: An electronic control unit of an internal combustion engine calculates a basic post-injection quantity of temperature increasing means if a deposition quantity of particulate matters deposited on a diesel particulate filter (DPF) exceeds a predetermined value. Then, a final post-injection quantity is calculated by correcting the basic post-injection quantity based on a temperature correction value, which is calculated by multiplying a deviation between DPF upstream exhaust gas temperature and target temperature and past temperature correction values by feedback gains. The feedback gains are switched in accordance with a delay in an exhaust gas temperature change in a present operating state, based on an intake air quantity sensed by an air flow meter. Thus, response can be improved, while maintaining stability.

Abstract: An engine control apparatus for a multi-cylinder compression ignition internal combustion engine includes a combustion status sensor and a controller. The combustion status sensor is installed in a selected one of cylinders of the engine. The controller works to sample an output from the combustion status sensor to determine a combustion status parameter and determine injection timings so as to bring the combustion status parameter into agreement with a target value. The controller also corrects the injection timing for at least one of the cylinders in which the combustion status sensor is not installed so that a combustion status parameter of the at least one of the cylinders lies on an advanced side of that of the one of the cylinders in which the combustion status sensor is installed, thereby avoiding the deterioration of quality of combustion of the fuel arising from a shift of the time of the ignition in the retarded direction from a desired time point.

Abstract: In a system, an actuator is linked to a valve rotatably installed in a passage through which gas flows. The actuator changes torque to be applied to the valve so as to adjust a rotational position of the valve based on a deviation between a current position and a target position. In the system, a first storing unit stores therein a first threshold. The first threshold is defined in a variation range within which a torque parameter is variable depending on change in the torque to be applied to the valve. The first threshold allows whether there is a possibility that an operation of the actuator is unstable. If the torque parameter substantially shifts either to or through the first threshold in the variation range, a restricting unit restricts variation in the torque parameter with the gas-flow being substantially kept through the passage.

Abstract: A gas concentration detector prevents deviation in output due to a difference in oxygen reactivity between electrode materials to accurately detect a specific gas component in a gas to be measured, such as NOx in an exhaust gas. A sensor element in an NOx sensor has a pump cell in a first chamber and a sensor cell for decomposing NOx and any remaining oxygen and a monitor cell for decomposing only remaining oxygen in a second chamber. An NOx concentration is detected based on a difference in current output between the sensor cell and the monitor cell. Since the sensor cell and the monitor cell have different oxygen reactivities, an output of the monitor cell is smoothed through a band-pass filter or the like so that output responses of the sensor cell and the monitor cell are made to substantially match each other, thereby eliminating any deviation in output.

Abstract: An ECU controls an opening degree of an EGR gas switch valve based on a temperature of intake air and a load state of an engine in such a manner that a temperature of exhaust gas becomes a suitable temperature, which is suitable for regeneration of a particulate filter arranged in an exhaust gas passage. In this way, cooled EGR gas, which passes a main passage, and hot EGR gas, which passes a bypass passage, are appropriately mixed. In a case, where reliability of an EGR valve cannot be maintained, EGR cut is performed.

Abstract: Deterioration of emission is restrained even if the actual control condition including the required torque is different from the set control condition. An ECU establishes a control amount of an EGR valve in such a manner that a condition amount, which is a control parameter controlling the EGR valve, is established as a target value. The ECU selects the condition amount as the control parameter among a fresh-air amount, an exhaust oxygen concentration, and an intake oxygen concentration, in which an operation amount of the EGR valve is minimum.

Abstract: When a combustion mode of an engine is a diffuse combustion mode in which an initial rising inclination of a heat-release-rate is steep, an electronic control unit (ECU) calculates an ignition timing in which the heat-release-rate exceeds an ignition determining value. Thus, even if a cylinder pressure sensor has a gain deviation or an offset deviation, the ignition timing is accurately detected to control the injection start timing. When the combustion mode is a premix combustion mode in which the initial rising inclination of the heat-release-rate is moderate, a peak arising timing of the heat-release-rate is calculated. Thus, the peak arising timing is accurately detected to control the injection start timing.

Abstract: An ECU converts a cylinder pressure P and a cylinder volume V corresponding to a crank angle ? at least from a compression stroke to a combustion and expansion stroke to a logarithmic value log P and a logarithmic value log V, respectively, to find a logarithmic conversion waveform and estimates a motoring waveform which is obtained by subtracting a pressure rise developed by combustion in a cylinder from the logarithmic conversion waveform, that is, corresponds to a non-combustion state. Further, the ECU computes a determination line Y of an ignition timing Tburn on the basis of the base line X of the estimated motoring waveform and determines the ignition timing Tburn on the basis of this determination line Y and the logarithmic conversion waveform.

Abstract: An ECU controls an opening degree of an EGR gas switch valve based on a temperature of intake air and a load state of an engine in such a manner that a temperature of exhaust gas becomes a suitable temperature, which is suitable for regeneration of a particulate filter arranged in an exhaust gas passage. In this way, cooled EGR gas, which passes a main passage, and hot EGR gas, which passes a bypass passage, are appropriately mixed. In a case, where reliability of an EGR valve cannot be maintained, EGR cut is performed.

Abstract: When a combustion mode of an engine is a diffuse combustion mode in which an initial rising inclination of a heat-release-rate is steep, an electronic control unit (ECU) calculates an ignition timing in which the heat-release-rate exceeds an ignition determining value. Thus, even if a cylinder pressure sensor has a gain deviation or an offset deviation, the ignition timing is accurately detected to control the injection start timing. When the combustion mode is a premix combustion mode in which the initial rising inclination of the heat-release-rate is moderate, a peak arising timing of the heat-release-rate is calculated. Thus, the peak arising timing is accurately detected to control the injection start timing.

Abstract: An electronic control unit (ECU) of a fuel injection control system of an internal combustion engine feedback-controls injection timing so that a cylinder pressure maximum value coincides with a target pressure value in an operation range, in which the cylinder pressure maximum value increases as ignition timing advances and torque increases as the ignition timing advances. The ECU feedback-controls the injection timing so that the ignition timing coincides with target timing in another operation range, in which the cylinder pressure maximum value increases as the ignition timing advances but the torque decreases as the ignition timing advances. Thus, the torque can be outputted efficiently by selecting the appropriate feedback control in accordance with the operation range.

Abstract: An electronic control unit (ECU) of an injection control system of an internal combustion engine determines that a load of a fuel pump is stabilized when a pressure-feeding operation delay elapses since a command pressure-feeding quantity outputted to the fuel pump reaches a certain pressure-feeding quantity necessary to maintain a target injection pressure. The ECU permits a single injection when a waiting period necessary to measure rotation speeds once for each cylinder before the single injection is performed elapses since the load of the fuel pump is stabilized. Thus, the single injection timing is determined based on the time point when the command pressure-feeding quantity is stabilized, the pressure-feeding operation delay, and the waiting period. Therefore, an injection quantity learning operation can be performed highly accurately in a short period.