A CPU substitutes a difference between a crank-side speed that is a rotation speed of a crankshaft and a downstream-side speed that is a speed of a portion, opposite from the crankshaft, in a damper into a differential speed. The CPU calculates a torsion speed component that is a speed component of the crankshaft due to torsion of the damper based on a physical model of which an input is the differential speed, and calculates a time that is a variable indicating a speed of the crankshaft, used to determine a misfire, based on the torsion speed component. The CPU delays acquisition time of the downstream-side speed used to calculate the differential speed, with respect to acquisition time of the crank-side speed according to the rotation speed of the crankshaft.

Disclosed is a method for forming a spacer extending at least partially within the length of a central bore passing from one side to the other of a barrel of a mounting base of an accelerometer sensor, the central bore being designed to receive a fastening element for fixing the mounting base onto a support element, the fastening element being centered by the spacer in the central bore, the mounting base being at least partially surrounded by an encapsulation of overmolded plastic material. When the plastic material is overmolded around the mounting base to form the encapsulation, a part of the plastic material passes through the barrel to form the spacer while fixing it to the encapsulation. Also described is a mounting base with at least one channel for the passage of the plastic material, and to an accelerometer sensor equipped with such a mounting base.

Disclosed is a method for forming a spacer extending at least partially within the length of a central bore passing from one side to the other of a barrel of a mounting base of an accelerometer sensor, the central bore being designed to receive a fastening element for fixing the mounting base onto a support element, the fastening element being centered by the spacer in the central bore, the mounting base being at least partially surrounded by an encapsulation of overmolded plastic material. When the plastic material is overmolded around the mounting base to form the encapsulation, a part of the plastic material passes through the barrel to form the spacer while fixing it to the encapsulation. Also described is a mounting base with at least one channel for the passage of the plastic material, and to an accelerometer sensor equipped with such a mounting base.

An individual cylinder air-fuel ratio estimation of estimating an air-fuel ratio of an individual cylinder is performed on a sensed value of an air-fuel ratio sensor set in an exhaust gas collection part of an engine, and an individual cylinder air-fuel ratio control of controlling the air-fuel ratio of the individual cylinder is performed in such a way that a variation in the air-fuel ratio between the cylinders becomes small on the basis of an estimated air-fuel ratio of the individual cylinder. Further, it is determined whether or not a misfire of the engine is caused and when it is determined that the misfire of the engine is caused, the individual cylinder air-fuel ratio estimation and the individual cylinder air-fuel ratio control are stopped and an individual cylinder correction value by the individual cylinder air-fuel ratio control is reset. In this way, it is possible to avoid the individual cylinder air-fuel ratio control from being performed continuously as usual in a state where the air-fuel ratio of the individual cylinder cannot be controlled correctly due to the effect of the misfire.

The control device for an internal combustion engine disclosed in the present application is a control device that determines the presence or absence of misfire based on an angle detection cycle calculated from an output signal of an angle sensor, the control device includes an arithmetic processing device and a storage device, the control device is configured so that the storage device stores the angle detection cycle calculated in a misfire detection threshold value comparison section after the reference angle section as a threshold value comparison target cycle and is configured such that the arithmetic processing device determines the presence or absence of misfire based on the misfire detection threshold value cycle calculated based on the reference detection cycle and the threshold value comparison target cycle, thereby it becomes possible to accurately determine the presence or absence of misfire in the control device for the internal combustion engine.

The control device for an internal combustion engine disclosed in the present application is a control device that determines the presence or absence of misfire based on an angle detection cycle calculated from an output signal of an angle sensor, the control device includes an arithmetic processing device and a storage device, the control device is configured so that the storage device stores the angle detection cycle calculated in a misfire detection threshold value comparison section after the reference angle section as a threshold value comparison target cycle and is configured such that the arithmetic processing device determines the presence or absence of misfire based on the misfire detection threshold value cycle calculated based on the reference detection cycle and the threshold value comparison target cycle, thereby it becomes possible to accurately determine the presence or absence of misfire in the control device for the internal combustion engine.

A misfire detecting system for an engine of a vehicle that detects a misfire of the engine is provided, which includes a processor. The processor determines whether a misfire has occurred by examining whether a fluctuation of a crank angle of the engine is equal to or greater than a determination reference value, acquires a value relating to a density of intake air introduced into the engine, and adjusts the determination reference value according to the value related to the density.

A misfire detecting system for an engine of a vehicle that detects a misfire of the engine is provided, which includes a processor. The processor determines whether a misfire has occurred by examining whether a fluctuation of a crank angle of the engine is equal to or greater than a determination reference value, acquires a value relating to a density of intake air introduced into the engine, and adjusts the determination reference value according to the value related to the density.

An electronic control unit sets a misfire determination threshold to a first value in the cylinder injection mode, and sets the misfire determination threshold to a second value smaller than the first value in the port injection mode, and determines that a misfire occurs in the engine when a rotation fluctuation of the engine is larger than the misfire determination threshold. In a case where the cylinder injection mode is changed to the port injection mode, when a predetermined period has elapsed from the change, the electronic control unit changes the misfire determination threshold from the first value to the second value.

A vehicle drive system includes an internal combustion engine, a clutch, an engine rotation speed detector, an output shaft rotation speed detector, and a processor. The internal combustion engine includes cylinders and a crankshaft. The clutch is connected to the crankshaft via a torsion element and includes an output shaft. The engine rotation speed detector detects a crankshaft rotation speed. The output shaft rotation speed detector detects an output shaft rotation speed. The processor is configured to calculate a torque generated in each of the cylinders based on the crankshaft rotation speed. The processor is configured to decrease transmission torque of the clutch so that a difference between the crankshaft rotation speed and the output shaft rotation speed to be a target value when misfiring occurs. The processor is configured to identify a misfiring cylinder among the cylinders based on the torque calculated while the transmission torque is decreased.