Abstract: The invention provides an engine controller, which can determine a deterioration mode (gain deterioration or response deterioration) of an air/fuel (A/F) ratio sensor, can detect a degree of the deterioration with high accuracy, and can optimize A/F ratio feedback control in accordance with the diagnosis result. The controller includes a unit for computing frequency response characteristics in a range from an A/F ratio adjusting unit to the A/F ratio sensor, and it diagnoses the A/F ratio sensor based on a gain characteristic and a response characteristic given by the computed frequency response characteristics. In accordance with the diagnosis result, parameters (P- and I-component gains) used in A/F ratio feedback control (PI control) are optimized.

Abstract: A control apparatus for an internal combustion engine has an oxygen storage volume computing unit for computing an oxygen storage volume of a catalyst by using a real air/fuel ratio detected by an air/fuel ratio sensor installed on the upstream side of a catalyst, a center air/fuel ratio representing a stoichiometric air/fuel ratio and an estimated air flow volume or detecting a flow rate of air flowing into the catalyst. A center air/fuel ratio correcting unit for correcting a center air/fuel ratio based on output of a rear air/fuel ratio sensor provided on the downstream side of the catalyst, and an oxygen storage volume computed by an oxygen storage volume computing unit, and the oxygen storage volume computing unit computes an oxygen storage volume by using a center air/fuel ratio corrected by the center air/fuel ratio correcting unit.

Abstract: A catalyst diagnosis apparatus comprises a reaction rate calculation unit for calculating a reaction rate of chemical reaction in a three-way catalyst based on an output of an oxygen sensor, and an OSC indicator calculation unit for calculating an OSC indicator indicating an oxygen storage capacity (OSC) of the three-way catalyst based on outputs of a linear air-fuel ratio sensor and the oxygen sensor, and a catalyst degradation determination unit for determining degradation of the three-way catalyst based on the reaction rate and the OSC indicator. The determination of the catalyst degradation can be performed with high accuracy in a manner adapted for influences of external environments, etc.

Abstract: A fault diagnosis apparatus for sensors in an apparatus system has at least three sensors which detect different physical quantities for one physical phenomenon which vary in correlation with one another, the sensors outputting signals indicating the detected physical quantities, wherein outputs from the at least three sensors are converted into one identical physical quantity in accordance with the correlations so that the resulting identical physical quantity can be used to determine whether or not each of the sensors is defective.

Abstract: A control apparatus is capable of separately detecting an unexpected fluctuation in the amount of NOx discharged from an engine (combustion chamber), separately from deterioration of lean NOx catalyst performance, thereby avoiding incorrect diagnosis of deterioration of the lean NOx catalyst, and ensuring the optimum control of the catalyst.

Abstract: In a lean-burn engine equipped, in the exhaust pipe, with NOx trap catalyst that collects NOx by absorption or occlusion, the rich spike start timing and rich spike volume are optimized. The above subject is achieved by an engine control system equipped, in the downstream side of the NOx trap catalyst, with a NOx sensor that detects the NOx component in the exhaust, NOx trap catalyst model, and a device that controls the engine operating condition based on the outputs of the NOx trap catalyst model and NOx sensor.

Abstract: In a diagnosis apparatus for an internal combustion engine which determines the abnormality of a linear A/F sensor which is disposed on the upstream side of a catalyst of the engine and detects the A/F of exhaust gas, the apparatus includes a response/gain deterioration detection unit that separately detects the response deterioration in which the response of the linear A/F sensor is delayed and the gain deterioration in which the detection sensitivity of the linear A/F sensor is abnormal.

Abstract: The invention provides a control apparatus of a cylinder injection of fuel type internal combustion engine executing a dilute combustion, which can satisfy a requirement of rapidly changing an engine torque while restricting a deterioration of a driving property and an exhaust gas as much as possible. In a control apparatus of a multicylinder engine executing a dilute combustion, in the case that a requirement of reducing and changing an engine torque of the internal combustion engine is applied, the control apparatus executes a fuel cut of a predetermined number of cylinders, and controls so that a torque of operating cylinders except the cylinders executing the fuel cut becomes the required engine torque.

Abstract: An internal combustion engine control device for, in a lean-burn internal combustion engine provided with a three-way catalyst and a lean NOx catalyst in an exhaust system, optimizing an air/fuel ratio in a rich mode from the viewpoints of both better fuel economy and exhaust emission control when NOx having been stored in a lean NOx catalyst during a lean operation is desorbed and cleaned by switching to a rich operation. An internal combustion engine control device for controlling an air/fuel ratio during the rich operation to be changed between a period of desorbing O2 stored in the three-way catalyst and a period of desorbing and cleaning NOx stored in the lean NOx catalyst.

Abstract: Pressure detection means detects the pressure of an evaporation purge system that includes a fuel tank and a communicating tube, which connects a canister for adsorbing and retaining fuel vapor to an intake pipe. Shutout means shuts out the evaporation purge system from atmospheric air. A pump is driven for pressurization or depressurization purposes while the shutout means shuts out the evaporation purge system from atmospheric air. The pump is stopped when the pressure detected by the pressure detection means reaches a predetermined level. A leak judgment is formulated in accordance with pump drive time and a pressure change after pump stoppage.

Abstract: In a system which applies a torque-based control to a direct injection engine with a turbocharger and is capable of switching between stoichiometric running and lean-burn running in accordance with a driving state, in order to provide a means for obtaining preferred exhaust performance and driveability, a turbo lag index is computed on the basis of supercharged pressure information or air intake pipe pressure information which are obtained directly or indirectly, and then a throttle opening or a fuel injection quantity is corrected on the basis of the above-described turbo lag index to obtain desired torque and exhaust characteristics. As a result, it is possible to prevent a torque variation, a change in torque characteristics, exhaust deterioration, or the like in a transient time, which are generated due to a turbo lag.

Abstract: A diagnostic device and method of an engine exhaust purifying system, which perform active control of an air-fuel ratio and can make diagnosis of air-fuel ratio sensors, catalysts, etc. in the engine exhaust purifying system with high accuracy and reliability while avoiding a worsening of exhaust emissions, an increase of revolution variations, etc.

Abstract: The invention provides an engine controller, which can determine a deterioration mode (gain deterioration or response deterioration) of an air/fuel (A/F) ratio sensor, can detect a degree of the deterioration with high accuracy, and can optimize A/F ratio feedback control in accordance with the diagnosis result. The controller includes a unit for computing frequency response characteristics in a range from an A/F ratio adjusting unit to the A/F ratio sensor, and it diagnoses the A/F ratio sensor based on a gain characteristic and a response characteristic given by the computed frequency response characteristics. In accordance with the diagnosis result, parameters (P- and I-component gains) used in A/F ratio feedback control (PI control) are optimized.

Abstract: A misfire detector is provided that is accurate even in the case of a disturbance due to causes such as driving on a rough road. The misfire detector is equipped with a crankshaft revolution detector to measure the time period required for the crankshaft of an internal-combustion engine to revolve for a given angle. A signal-processor is also provided for detecting the misfiring of the internal-combustion engine by processing the time period. In one embodiment, the misfire detector has two filters having the same sensitivity to the misfire frequency, and differing in the sensitivity to frequencies adjacent to said misfire frequency. It can be determined that a misfire has occurred if the ratio or difference between the outputs of the two filters stays within a fixed range and one or both of the filters have respective outputs exceeding a threshold value.

Abstract: Disclosed is an internal combustion engine controller, which is used with a fuel-based torque-on-demand control type, multi-cylinder, direct-injection internal combustion engine to provide an air flow rate control means that excels in response and convergence. This internal combustion engine controller comprises means for computing a target throttle opening from operating conditions. The means for computing a target throttle opening includes: a first computing means for determining a target throttle opening by exercising feedback control in accordance with operating conditions including an intake air flow rate; a second computing means for determining a target throttle opening by exercising feed-forward control in accordance with operating conditions; and a third computing means for determining a target throttle opening in accordance with a target throttle opening value determined by the first computing means and a target throttle opening value determined by the second computing means.

Abstract: A control apparatus capable of separately detecting an unexpected fluctuation in the amount of NOx discharged from an engine (combustion chamber), separately from deterioration of lean NOx catalyst performance, thereby avoiding incorrect diagnosis of deterioration of the lean NOx catalyst, and ensuring the optimum control of the catalyst. A control apparatus of an engine wherein a lean NOx catalyst having a function of storing the NOx discharged from a combustion chamber in the lean operation mode, and desorbing and cleaning the stored NOx in the rich operation mode is provided in an exhaust path.

Abstract: The invention provides a control apparatus of a cylinder injection of fuel type internal combustion engine executing a dilute combustion, which can satisfy a requirement of rapidly changing an engine torque while restricting a deterioration of a driving property and an exhaust gas as much as possible. In a control apparatus of a multicylinder engine executing a dilute combustion, in the case that a requirement of reducing and changing an engine torque of the internal combustion engine is applied, the control apparatus executes a fuel cut of a predetermined number of cylinders, and controls so that a torque of operating cylinders except the cylinders executing the fuel cut becomes the required engine torque.

Abstract: In a lean-burn engine equipped, in the exhaust pipe, with NOx trap catalyst that collects NOx by absorption or occlusion, the rich spike start timing and rich spike volume are optimized.

Abstract: A failure diagnosis apparatus for an exhaust gas recirculation system eliminates the influence of various disturbance factors that vary the suction air pressure, diagnoses a failure of the exhaust gas recirculation system on the basis of the suction air pressure, and prevents incorrect diagnosis. The system includes a fresh air pressure unit for determining an estimated fresh air pressure inside a suction pipe from the operating condition of an internal combustion engine and an actual exhaust gas recirculation pressure estimating unit for determining an EGR gas pressure on the basis of a measured suction pipe pressure detected by a suction pipe pressure detecting unit and estimated fresh air pressure. A failure is judged on the basis of the estimated EGR gas pressure and the detected operating condition.

Abstract: A misfire detector is provided that is accurate even in the case of a disturbance due to causes such as driving on a rough road. The misfire detector is equipped with a crankshaft revolution detector to measure the time period required for the crankshaft of an internal-combustion engine to revolve for a given angle. A signal-processor is also provided for detecting the misfiring of the internal-combustion engine by processing the time period. In one embodiment, the misfire detector has two filters having the same sensitivity to the misfire frequency, and differing in the sensitivity to frequencies adjacent to said misfire frequency. It can be determined that a misfire has occurred if the ratio or difference between the outputs of the two filters stays within a fixed range and one or both of the filters have respective outputs exceeding a threshold value.