This control device for an internal combustion engine is equipped with: an air/fuel ratio sensor provided to the exhaust passage of an internal combustion engine; and an engine control device that controls the internal combustion engine on the basis of the sensor output current of the air/fuel ratio sensor. The air/fuel ratio sensor is equipped with: a gas chamber to be measured, into which exhaust gas flows; a reference cell for which the reference cell output current varies according to the air/fuel ratio of the exhaust gas inside the gas chamber to be measured; and a pump cell that, according to the pump current, pumps oxygen into or out of the exhaust gas in the gas chamber to be measured. The reference cell is configured so that the applied voltage, at which the reference cell output current reaches zero, varies according to the air/fuel ratio of the exhaust gas in the gas chamber to be measured. The applied voltage in the reference cell is fixed at a constant voltage, said constant voltage being set to a voltage different to the voltage at which the reference cell output current reaches zero when the air/fuel ratio of the exhaust gas in the gas chamber to be measured is the stoichiometric air/fuel ratio.

A delay module, based on a base request received for a first loop, sets a delayed base request for a second loop. A first period between the first and second loops corresponds to: a first delay period of an oxygen sensor; and a second delay period for exhaust to flow from a cylinder of an engine to the oxygen sensor. A closed loop module determines a closed loop correction for the second loop based on: the delayed base request for the second loop; a measurement from the oxygen sensor; the closed loop correction for the first loop; and the closed loop correction for a third loop. A second period between the second and third loops corresponds to the first delay period of the oxygen sensor. A summer module sets a final request for the second loop based on the base request plus the closed loop correction for the second loop.

A control device for an internal combustion engine, equipped with: an exhaust purification catalyst provided in the exhaust passage of the internal combustion engine and capable of absorbing oxygen; a downstream air-fuel ratio sensor provided downstream from the exhaust purification catalyst in the direction of the exhaust flow; and an engine control device that controls the internal combustion engine in response to the output from the downstream air-fuel ratio sensor. The downstream air-fuel ratio sensor is configured such that the applied voltage for which the output current is zero changes in response to the exhaust air-fuel ratio, and such that when the exhaust air-fuel ratio equals the theoretical air-fuel ratio and the applied voltage in the downstream air-fuel ratio sensor is increased, the output current increases in conjunction therewith. When the air-fuel ratio of the exhaust gas is detected by the downstream air-fuel ratio sensor, the applied voltage in the downstream air-fuel ratio sensor is fixed at a constant voltage, with this constant voltage being a voltage for which the output current is zero when the exhaust air-fuel ratio is a predetermined air-fuel ratio that is leaner than the theoretical air-fuel ratio.

A control apparatus for an internal combustion engine having a limiting current sensor includes an electronic control unit. The electronic control unit is configured to: (i) calculate a parameter relating to SOx contained in a detection subject gas using an output current of the sensor obtained when voltage reduction control is implemented to reduce an applied voltage applied to the sensor from a parameter calculation voltage; and (ii) implement the voltage reduction control when an oxygen concentration of the detection subject gas is less than a predetermined concentration or a low oxygen concentration condition, according to which an oxygen concentration of the detection subject gas is predicted to be less than a predetermined concentration, is established.

A delay module, based on a base request received for a first loop, sets a delayed base request for a second loop. A first period between the first and second loops corresponds to: a first delay period of an oxygen sensor; and a second delay period for exhaust to flow from a cylinder of an engine to the oxygen sensor. A closed loop module determines a closed loop correction for the second loop based on: the delayed base request for the second loop; a measurement from the oxygen sensor; the closed loop correction for the first loop; and the closed loop correction for a third loop. A second period between the second and third loops corresponds to the first delay period of the oxygen sensor. A summer module sets a final request for the second loop based on the base request plus the closed loop correction for the second loop.

A fuel vapor processing apparatus includes an adsorbent canister, a vapor path connecting the adsorbent canister to a fuel tank, and a flow control valve disposed in the vapor path. The flow control valve is kept closed while a movement distance of a valve body from a predetermined initial position toward a valve opening direction is less than a predetermined distance. A control unit comprising part of the apparatus is configured to set a valve opening speed of the flow control valve to a first speed under a condition where the movement distance of the valve body is less than the predetermined distance, and to set the valve opening speed of the flow control valve to a second speed lower than the first speed under a condition where the movement distance of the valve body is greater than the predetermined distance.

When executing a Local-learning, an air-fuel ratio detecting time is corrected so that a dispersion of detection values of an air-fuel ratio sensor becomes a maximum value in one cycle of an engine. While executing a cylinder-by-cylinder air-fuel ratio control, a Global-learning is executed. In the Global-learning, the air-fuel ratio detecting time is corrected based on a relationship between a variation in estimated air fuel ratio of each cylinder and a variation in fuel quantity correction value of each cylinder. In the Global-learning, a computer computes a correlation coefficient between the variation in estimated air-fuel ratio and the variation in fuel quantity correction value of the cylinder for each case where the cylinder assumed to correspond to the estimated air fuel ratio is hypothetically varied in multiple ways. Then, the air-fuel ratio detecting time is corrected so that this correlation coefficient becomes a maximum value.

In a diesel engine, an inside of a cylinder is divided into intra-cavity and extra-cavity regions. Ideal heat release rate waveform models, each formed of an isosceles triangle in which each oblique line gradient is a reaction rate, an area is a reaction amount and a base length is a reaction period with a reaction start temperature as a base point, are generated respectively for a vaporization reaction, low-temperature oxidation reaction, thermal decomposition reaction and high-temperature oxidation reaction of injected fuel for each region. An ideal heat release rate waveform of the reaction modes is generated by smoothing the ideal heat release rate waveform models through filtering and combining the ideal heat release rate waveforms, and is compared with an actual heat release rate waveform obtained from a detected in-cylinder pressure. A reaction mode having a deviation larger than or equal to a predetermined amount is diagnosed as being abnormal.

The invention relates to a method for determining an effective prevailing uncertainty value (304, 305) for an emission value (301, 302) for a given time point when operating a drivetrain (100) of a motor vehicle with an internal-combustion engine (110), wherein, at different times (n), one prevailing emission value (301) and one prevailing uncertainty value (303) are determined for the emission value, wherein the effective prevailing uncertainty value (304, 305) for the given time point is determined from prevailing uncertainty values (303) and prevailing emission values (301) prior to the given time point.

To further reduce pollutant emissions during operation of an internal combustion using an exhaust catalytic converter and in particular to promptly detect and possibly even prevent a departure from the catalytic converter window, a first oxygen filling level in a front area of the exhaust catalytic converter and a second oxygen filling level in a rear area be determined as a function of a signal of a lambda sensor and that the fuel mixture of the internal combustion engine be influenced as a function of the two oxygen filling levels with the aid of a fuzzy controller.