A control device for controlling an internal combustion engine equipped with an engine body, a variable compression ratio mechanism A configured to be able to change a mechanical compression ratio of the engine body, and an intake system configured to be able to make exhaust discharged from combustion chambers of the engine body be recirculated to an intake passage of the engine body. The control device is provided with a compression ratio control part controlling the variable compression ratio mechanism A so that the mechanical compression ratio becomes the target compression ratio. The compression ratio control part sets the target compression ratio at a lower value when exhaust is being recirculated at a predetermined operating region at an engine low load side than when exhaust is not being recirculated.

It is an object of the present invention to provide a control device for an internal combustion engine capable of appropriately controlling compression ratio and ignition timing before the target compression ratio that is set according to humidity is attained. A control device for an internal combustion engine controls the internal combustion engine including a cylinder, humidity detection means for detecting humidity of outside air supplied to the cylinder, a variable compression ratio mechanism for changing a compression ratio of the cylinder, and an ignition device igniting air-fuel mixture in the cylinder, and the control device includes: a compression ratio control unit controlling the variable compression ratio mechanism; and an ignition control unit controlling ignition timing of the ignition device, wherein corresponding characteristics between compression ratio and ignition timing are determined for each humidity according to a predetermined condition of an operation state of the internal combustion engine, the compression ratio control unit determines a target compression ratio of the variable compression ratio mechanism according to the detected humidity, and while the variable compression ratio mechanism changes a compression ratio to the target compression ratio, the ignition control unit controls the ignition device on the basis of corresponding characteristics determined according to the detected humidity.

A control device for an internal combustion engine including a variable compression ratio mechanism for changing a compression ratio by using an electric actuator prohibits control of changing the compression ratio to a higher compression ratio when a failure occurs in the variable compression ratio mechanism. Thereby, upon failure occurrence, the compression ratio of the variable compression ratio mechanism at the time of the failure occurrence is maintained or reduced to less than this compression ratio so as to protect the electric actuator and prevent abrupt changes in torque.

When a stopper portion is brought into abutment against body high-compression-ratio side stopper portion, when viewed in the control shaft axial direction, it is configured that the distance between body high-compression-ratio side stopper surface and control-shaft high-compression-ratio side stopper surface becomes relatively longer as being closer to the control shaft rotation center. Similarly, when a stopper portion is brought into abutment against body low-compression-ratio side stopper portion, when viewed in the control shaft axial direction, the distance between body low-compression-ratio side stopper surface and control-shaft, low-compression-ratio side stopper surface becomes relatively longer as being closer to the control shaft rotation center.

An object of the present invention is to provide a variable mechanism apparatus for an internal combustion engine capable of preventing a crown surface of a piston and intake and exhaust valves from interfering with each other or sufficiently acquiring an internal EGR effect during an exhaust stroke when a piston position at a compression top dead center is raised to achieve a high mechanical compression ratio. The variable mechanism apparatus is configured to set a piston position at an intake (exhaust) top dead center to a lower position than the piston position at the compression top dead center by a variable compression ratio mechanism. According thereto, the variable mechanism apparatus can prevent the crown surface of the piston and the intake and exhaust valves from interfering with each other or sufficiently acquiring the internal EGR effect during the exhaust stroke by setting the piston position at the exhaust top dead center to the low position when the piston position at the compression top dead center is raised to achieve the high mechanical compression ratio.

The present invention relates to a control device and to a control method for a vehicle drive mechanism including a moving body having a movability range regulated by two stoppers, and a sensor which senses a position of the moving body. The control device of the present invention learns an output of the sensor corresponding to a contact state of a high-rigidity stopper, and limits, to a lower level, an operation variable of the actuator for moving the moving body toward a low-rigidity stopper along with an increase in an amount of change in the output of the sensor from the contact state of the high-rigidity stopper. Then, the control device learns the output of the sensor corresponding to the contact state of the low-rigidity stopper, and controls the actuator based on the output of the sensor learned at both the stopper positions.

An internal combustion engine (1) is provided with a supercharger (12) and a cylinder direct injection fuel injector (10). When the engine shifts in a low-speed supercharging region at a state where the wall temperature of a cylinder bore (3) is low, liquid fuel adheres to a wall surface of the cylinder bore (3) so that lubricating oil is diluted with the liquid fuel and released into a combustion chamber (4). As a result, there occurs abnormal combustion. In the present invention, the fuel injection amount is increased at the time when the engine shifts in a predetermined low-speed supercharging region. The lower the wall temperature of the cylinder bore, the larger the rate of increase of the fuel injection amount. This makes it possible to suppress the temperature of air-fuel mixture in the vicinity of compression top dead center and prevent the occurrence of abnormal combustion.

A failure diagnosis apparatus according to the present disclosure is applied to a variable compression ratio mechanism that can switch the compression ratio of an internal combustion engine between at least a first compression ratio and a second compression ratio lower than the first compression ratio. When the variable compression ratio mechanism is controlled so as to set the compression ratio of the internal combustion engine to the second compression ratio, the failure diagnosis apparatus advances the ignition timing of one cylinder to a knock inducing ignition timing more advanced than the MBT that does not lead to the occurrence of knock if the actual compression ratio of that cylinder is the second compression ratio but leads to the occurrence of knock if the actual compression ratio of that cylinder is the first compression ratio and diagnoses failure of the variable compression ratio mechanism on the basis of whether knock occurs or not.

This internal combustion engine provided with a variable compression ratio mechanism is equipped with a turbocharger, the opening degree of a wastegate valve is controlled to a target opening degree for each engine operating state, and when the mechanical compression ratio is changed, the target opening degree of the wastegate valve for the current engine operating state is revised.

In a vehicle with an automatic transmission, an internal combustion engine is provided with a variable compression ratio mechanism. A target compression ratio of the variable compression ratio mechanism is determined based on a demand load and an engine rotation speed with reference to a compression ratio map. A reverse-drive compression ratio map is selected when the automatic transmission is in a reverse drive position; a first compression ratio map is selected when an actual speed reduction ratio of the transmission is low; and a second compression ratio map is selected when the actual speed reduction ratio of the transmission is high. A variable control range of the compression ratio is narrower in the second compression ratio map than in the first compression ratio map and is narrower in the reverse-drive compression ratio map than in the first and second compression ratio maps.