Abstract: An abnormality detection apparatus for a multi-cylinder internal combustion engine changes a fuel injection quantity of a predetermined target cylinder to detect an abnormality of an internal combustion engine based on values of rotational variations relating to the target cylinder detected before and after the change of the fuel injection quantity. The abnormality detection apparatus corrects the values of the rotational variations relating to the target cylinder detected before and after the change of the fuel injection quantity based on at least one of the number of revolutions of the engine and an engine load at a corresponding detection time.

Abstract: The invention provides an inter-cylinder air/fuel ratio imbalance determination apparatus and method. The determination apparatus includes a “limiting current type air/fuel ratio sensor”, and acquires a pre-correction index quantity that is greater the greater the degree of non-uniformity of the cylinder-by-cylinder air/fuel ratios, on the basis of a time differential value of the output value of the air/fuel ratio sensor. The determination apparatus obtains as the correction-purpose output value an average value of the output value obtained during a fuel-cut operation. The correction-purpose output value is greater the higher the responsiveness of the air/fuel ratio sensor. The determination apparatus acquires an air/fuel ratio imbalance index value by correcting the pre-correction index quantity so that the pre-correction index quantity is smaller the greater the correction-purpose output value.

Abstract: A fuel injection amount control apparatus includes an air-fuel ratio sensor which is disposed between an exhaust gas merging portion HK and an upstream catalyst. The control apparatus performs a feedback correction on an amount of fuel to be injected by the fuel injection valve in such a manner that an air-fuel ratio represented by an output value of an upstream air-fuel ratio sensor becomes equal to a target air-fuel ratio which is set at stoichiometric air-fuel ratio. The control apparatus obtains an air-fuel ratio imbalance indicating value, which becomes larger as a difference in air-fuel ratio of each of the mixtures supplied to each of the combustion chambers among the cylinders becomes larger, and performs an increasing correction to the amount of fuel to be injected by the injection valve in such a manner that an air-fuel ratio becomes a richer air-fuel ratio than the stoichiometric air-fuel ratio as the obtained air-fuel ratio imbalance indicating value becomes larger.

Abstract: The invention provides an inter-cylinder air-fuel ratio imbalance abnormality detection device for a multi-cylinder internal combustion engine, in which when abnormality detection processing of detecting an inter-cylinder air-fuel ratio imbalance abnormality on the basis of revolution speed fluctuations of the multi-cylinder internal combustion engine and ignition timing control for controlling the ignition timing so as to restrict revolution speed fluctuations in the multi-cylinder internal combustion engine are implemented, the implementation of the ignition timing control is restricted when the abnormality detection processing is implemented, and an abnormality detection method to be used in such a device.

Abstract: An engine ECU calculates a rotational variation based on a required rotation time when a complete misfire occurs in a cylinder, a required rotation time when complete combustion occurs in the cylinder, and a required rotation time during the current combustion stroke, and integrates the calculated rotational variation. If it is determined that the number of times the rotational variation has been integrated has reached a predetermined number, the engine ECU calculates an amount of learning value deviation from the integrated rotational variation. If the amount of learning value deviation is equal to or greater than a certain amount, the engine ECU corrects a learning value of a sub-feedback control with respect to the air-fuel ratio.

Abstract: An abnormality detection apparatus for a multi-cylinder internal combustion engine changes a fuel injection quantity of a predetermined target cylinder to detect an abnormality of an internal combustion engine based on values of rotational variations relating to the target cylinder detected before and after the change of the fuel injection quantity. The abnormality detection apparatus corrects the values of the rotational variations relating to the target cylinder detected before and after the change of the fuel injection quantity based on at least one of the number of revolutions of the engine and an engine load at a corresponding detection time.

Abstract: An apparatus for detecting imbalance abnormality in an air-fuel ratio between cylinders in a multi-cylinder internal combustion engine according to the present invention increases a fuel injection quantity to a predetermined target cylinder to detect imbalance abnormality in an air-fuel ratio between cylinders at least based upon a rotation variation of the target cylinder after increasing the fuel injection quantity. The increase in the fuel injection quantity is carried out in the middle of performing the post-fuel-cut rich control. Since timing of the post-fuel cut rich control is used to increase the fuel injection quantity, the exhaust emission deterioration due to abnormality detection execution can be prevented as much as possible.

Abstract: The invention provides an inter-cylinder air-fuel ratio imbalance abnormality detection device for a multi-cylinder internal combustion engine, in which when abnormality detection processing of detecting an inter-cylinder air-fuel ratio imbalance abnormality on the basis of revolution speed fluctuations of the multi-cylinder internal combustion engine and ignition timing control for controlling the ignition timing so as to restrict revolution speed fluctuations in the multi-cylinder internal combustion engine are implemented, the implementation of the ignition timing control is restricted when the abnormality detection processing is implemented, and an abnormality detection method to be used in such a device.

Abstract: The invention provides an inter-cylinder air/fuel ratio imbalance determination apparatus and method. The determination apparatus includes a “limiting current type air/fuel ratio sensor”, and acquires a pre-correction index quantity that is greater the greater the degree of non-uniformity of the cylinder-by-cylinder air/fuel ratios, on the basis of a time differential value of the output value of the air/fuel ratio sensor. The determination apparatus obtains as the correction-purpose output value an average value of the output value obtained during a fuel-cut operation. The correction-purpose output value is greater the higher the responsiveness of the air/fuel ratio sensor. The determination apparatus acquires an air/fuel ratio imbalance index value by correcting the pre-correction index quantity so that the pre-correction index quantity is smaller the greater the correction-purpose output value.

Abstract: An engine ECU calculates a rotational variation based on a required rotation time when a complete misfire occurs in a cylinder, a required rotation time when complete combustion occurs in the cylinder, and a required rotation time during the current combustion stroke, and integrates the calculated rotational variation. If it is determined that the number of times the rotational variation has been integrated has reached a predetermined number, the engine ECU calculates an amount of learning value deviation from the integrated rotational variation. If the amount of learning value deviation is equal to or greater than a certain amount, the engine ECU corrects a learning value of a sub-feedback control with respect to the air-fuel ratio.

Abstract: An apparatus and method for controlling the intake air amount in an internal combustion engine provided with a throttle valve and an intake air amount changing means linked with the same, the intake air amount control apparatus and method of an internal combustion engine finding a target intake air amount mcta based on an accelerator opening degree and engine speed (step 101), determining a target setting Cvta for said intake air amount changing means based on at least said target intake air amount (step 103), and finding a target throttle opening degree ?tta based on model equations creating a model of an engine intake system and expressing the air passing through the engine intake system from said target intake air amount mcta and the target setting Cvta (step 107).

Abstract: A cylinder air filling amount is divided into a first amount of air and a second amount of air, the first amount of air and the second amount of air are calculated, and the first amount of air and the second amount of air are totaled to calculate a cylinder air filling amount. The first amount of air is the excess of the cylinder air filling amount with respect to the throttle valve air passage amount occurring due to an intake stroke being performed. The drop in intake pressure occurring due to an intake stroke being performed is detected for each cylinder and the total value of the intake pressure drop in a 720° crank angle range is calculated. The first amount of air is calculated based on an intake pressure drop and the intake pressure drop total value. Due to this, it is possible to simply and accurately calculate a cylinder air filling amount.

Abstract: An intake pressure is successively detected by a pressure sensor, and an intake pressure derivative is calculated. Next, a peak pressure detecting range for each cylinder is set based on the intake pressure derivative. Next, an upward peak pressure and a downward peak pressure of the intake pressure, included in the peak pressure detecting range, are detected for each cylinder. Next, an intake pressure drop for each cylinder is calculated from the upward peak pressure and the downward peak pressure. The in-cylinder charged air amount is calculated based on the intake pressure drop.

Abstract: A cylinder air filling amount is divided into a first amount of air and a second amount of air, the first amount of air and the second amount of air are calculated, and the first amount of air and the second amount of air are totaled to calculate a cylinder air filling amount. The first amount of air is the excess of the cylinder air filling amount with respect to the throttle valve air passage amount occurring due to an intake stroke being performed. The drop in intake pressure occurring due to an intake stroke being performed is detected for each cylinder and the total value of the intake pressure drop in a 720° crank angle range is calculated. The first amount of air is calculated based on an intake pressure drop and the intake pressure drop total value. Due to this, it is possible to simply and accurately calculate a cylinder air filling amount.

Abstract: An engine body includes a plurality of cylinders, and the intake valve lift-amount of each cylinder is changed based on the engine operating state. A pressure sensor continuously detects the intake pressure, which is the pressure in an intake pipe, to detect the intake pressure decrease amount, which is the amount of decrease in the intake pressure caused due to execution of the intake stroke, of each cylinder. The air quantity variation correction coefficient, which is used to compensate for the variation in the in-cylinder supplied-air quality with each cylinder, is calculated based on the detected intake pressure decrease amount, and the fuel injection amount is corrected using the air quantity variation correction coefficient.

Abstract: An intake pressure is successively detected by a pressure sensor, and an intake pressure derivative is calculated. Next, a peak pressure detecting range for each cylinder is set based on the intake pressure derivative. Next, an upward peak pressure and a downward peak pressure of the intake pressure, included in the peak pressure detecting range, are detected for each cylinder. Next, an intake pressure drop for each cylinder is calculated from the upward peak pressure and the downward peak pressure. The in-cylinder charged air amount is calculated based on the intake pressure drop.

Abstract: An apparatus and method for controlling the intake air amount in an internal combustion engine provided with a throttle valve and an intake air amount changing means linked with the same, the intake air amount control apparatus and method of an internal combustion engine finding a target intake air amount mcta based on an accelerator opening degree and engine speed (step 101), determining a target setting Cvta for said intake air amount changing means based on at least said target intake air amount (step 103), and finding a target throttle opening degree ?tta based on model equations creating a model of an engine intake system and expressing the air passing through the engine intake system from said target intake air amount mcta and the target setting Cvta (step 107).

Abstract: An engine body includes a plurality of cylinders, and the intake valve lift-amount of each cylinder is changed based on the engine operating state. A pressure sensor continuously detects the intake pressure, which is the pressure in an intake pipe, to detect the intake pressure decrease amount, which is the amount of decrease in the intake pressure caused due to execution of the intake stroke, of each cylinder. The air quantity variation correction coefficient, which is used to compensate for the variation in the in-cylinder supplied-air quality with each cylinder, is calculated based on the detected intake pressure decrease amount, and the fuel injection amount is corrected using the air quantity variation correction coefficient.

Abstract: A control apparatus is provided for a valve actuating system which is operable to lift an intake valve or an exhaust valve of an internal combustion engine and includes a lift characteristic changing mechanism for changing a lift characteristic of the intake valve or the exhaust valve. The control apparatus calculates a target operation value of the lift characteristic changing mechanism, and calculates a realizable range of the operation value which can be realized by the lift characteristic changing mechanism, based on a controlled variable that can be given to the lift characteristic changing mechanism and at least one parameter related to an environment surrounding the lift characteristic changing mechanism. If the target operation value is not within the realizable range of the operation value, the control apparatus calculates a new target operation value to be within the realizable range.

Abstract: A control apparatus is provided for a valve actuating system which is operable to lift an intake valve or an exhaust valve of an internal combustion engine and includes a lift characteristic changing mechanism for changing a lift characteristic of the intake valve or the exhaust valve. The control apparatus calculates a target operation value of the lift characteristic changing mechanism, and calculates a realizable range of the operation value which can be realized by the lift characteristic changing mechanism, based on a controlled variable that can be given to the lift characteristic changing mechanism and at least one parameter related to an environment surrounding the lift characteristic changing mechanism. If the target operation value is not within the realizable range of the operation value, the control apparatus calculates a new target operation value to be within the realizable range.