Abstract: An anomaly diagnosing apparatus is adapted for a cooling device in an internal combustion engine. The apparatus is configured to execute an enlarging process, a rate calculating process, and an anomaly determining process. The enlarging process includes enlarging the cross-sectional area of the flow passage between an inner channel and an outer channel in the cooling device. The rate calculating process includes calculating a reference rate for a rate of rise of temperature of cooling water. The anomaly determining process includes determining that an anomaly is present in the check valve if a rate of rise of a detection value of cooling water temperature is smaller than the reference rate. The rate calculating process includes calculating the reference rate such that the reference rate has a smaller value in a case where the enlarging process is executed than in a case where the enlarging process is not executed.

Abstract: An anomaly diagnosing apparatus is adapted for a cooling device in an internal combustion engine. The apparatus is configured to execute an enlarging process, a rate calculating process, and an anomaly determining process. The enlarging process includes enlarging the cross-sectional area of the flow passage between an inner channel and an outer channel in the cooling device. The rate calculating process includes calculating a reference rate for a rate of rise of temperature of cooling water. The anomaly determining process includes determining that an anomaly is present in the check valve if a rate of rise of a detection value of cooling water temperature is smaller than the reference rate. The rate calculating process includes calculating the reference rate such that the reference rate has a smaller value in a case where the enlarging process is executed than in a case where the enlarging process is not executed.

Abstract: A control apparatus for an internal combustion engine (i) acquires a rotational speed signal correlated with a rotational speed of the internal combustion engine, (ii) extracts, from the acquired rotational speed signal, at least first-order and lower-order than the first-order components of the rotational speed signal, (iii) extracts, from the acquired rotational speed signal, at least an n-th-order component of the rotational speed signal, (iv) determines that no disturbance has occurred when a first-order parameter regarding a magnitude of an amplitude of the extracted first-order and lower-order than the first-order components is smaller than a first threshold, and (v) determines that a disturbance has occurred when the first-order parameter is equal to or larger than the first threshold and an n-th-order parameter regarding an amplitude of the extracted n-th-order component is equal to or larger than a second threshold.

Abstract: A control apparatus for an internal combustion engine (i) acquires a rotational speed signal correlated with a rotational speed of the internal combustion engine, (ii) extracts, from the acquired rotational speed signal, at least first-order and lower-order than the first-order components of the rotational speed signal, (iii) extracts, from the acquired rotational speed signal, at least an n-th-order component of the rotational speed signal, (iv) determines that no disturbance has occurred when a first-order parameter regarding a magnitude of an amplitude of the extracted first-order and lower-order than the first-order components is smaller than a first threshold, and (v) determines that a disturbance has occurred when the first-order parameter is equal to or larger than the first threshold and an n-th-order parameter regarding an amplitude of the extracted n-th-order component is equal to or larger than a second threshold.

Abstract: An apparatus for detecting imbalance abnormality in an air-fuel ratio between cylinders in a multi-cylinder internal combustion engine is disclosed. The apparatus includes an imbalance determining unit programmed to determine imbalance in an air-fuel ratio of a first cylinder belonging to a cylinder group based upon a difference value between an index value correlative with a crank angular speed detected in the first cylinder and an index value correlative with a crank angular speed detected in a second cylinder belonging to another cylinder group, and further a correction unit programmed to correct the difference value for the first cylinder based upon the index value detected in at least one of other cylinders belonging to the same cylinder group as that of the first cylinder.

Abstract: An inter-cylinder air-fuel ratio variation abnormality detection apparatus is disclosed. The apparatus determines imbalance of an air-fuel ratio among the cylinders based on a difference between index values correlated with crank angular velocities detected in a set of opposite cylinders belonging to different banks and having crank angles different from one another by 360°; and carries out an air-fuel ratio feedback process for controlling an amount of injected fuel for each of the banks, wherein the apparatus comprises a correction unit correcting, before determining the air-fuel ratio imbalance, the difference between the index values in a direction of combustion improvement for opposite cylinders that are opposite to cylinders belonging to a bank identical to a bank of a cylinder with the most deviating index value from a standard value among all the cylinders and being other than the cylinder with the most deviating index value.

Abstract: An apparatus for detecting imbalance abnormality in an air-fuel ratio between cylinders in a multi-cylinder internal combustion engine is disclosed. The apparatus includes an imbalance determining unit programmed to determine imbalance in an air-fuel ratio of a first cylinder belonging to a cylinder group based upon a difference value between an index value correlative with a crank angular speed detected in the first cylinder and an index value correlative with a crank angular speed detected in a second cylinder belonging to another cylinder group, and further a correction unit programmed to correct the difference value for the first cylinder based upon the index value detected in at least one of other cylinders belonging to the same cylinder group as that of the first cylinder.

Abstract: An inter-cylinder air-fuel ratio variation abnormality detection apparatus is disclosed. The apparatus determines imbalance of an air-fuel ratio among the cylinders based on a difference between index values correlated with crank angular velocities detected in a set of opposite cylinders belonging to different banks and having crank angles different from one another by 360°; and carries out an air-fuel ratio feedback process for controlling an amount of injected fuel for each of the banks, wherein the apparatus comprises a correction unit correcting, before determining the air-fuel ratio imbalance, the difference between the index values in a direction of combustion improvement for opposite cylinders that are opposite to cylinders belonging to a bank identical to a bank of a cylinder with the most deviating index value from a standard value among all the cylinders and being other than the cylinder with the most deviating index value.

Abstract: The “imbalance index value” representing the magnitude of the difference among the cylinder-by-cylinder air-fuel ratios (imbalance of air-fuel ratios among cylinders) is acquired based on the output value of the air-fuel ratio sensor disposed above the catalyst. The execution of the emission reduction control is “limited” when the magnitude of the imbalance of air-fuel ratios among cylinders represented by the imbalance index value is the first degree or more, and less than the second degree which is larger than the first degree, and is “prohibited” when it is the second degree or more. As the emission reduction control, a purge control, an EGR control, an Al incremental control, a cold VVT control, a catalyst warm-up delay angle control, an SCV control, and the like can be exemplified. Misfire due to the execution of emission reduction control are suppressed, when the imbalance of air-fuel ratios among cylinders occurs.