A control device for an internal combustion engine and a control method for a variable mechanism for an internal combustion engine for a vehicle, according to the present invention, is configured to maintain a drive stopped state of an electric actuator of the variable mechanism when a position of the electric actuator does not change in a case in which the position of the electric actuator is apart from stoppers and the electric actuator is stopped, whereas to restart driving the electric actuator when the position of the electric actuator changes. In this way, it is possible to prevent wasteful power consumption while the internal combustion engine is stopped.

Methods and systems are provided for adjusting a compression ratio. In one example, a system may include rotating an eccentric ring of a crankshaft by flowing hydraulic fluid to first and second chambers to actuate the eccentric ring.

Provided is an actuator for a variable compression ratio mechanism of an internal combustion engine, which improves productivity. The actuator for a variable compression ratio mechanism of an internal combustion engine includes an electric motor; a control shaft to which a rotative force from the electric motor is transmitted, the control shaft including a first journal portion and a second journal portion; an arm link portion that is disposed between the first journal portion and the second journal portion in an axial direction and extends from the control shaft in a radial direction, where the axial direction is a direction along a rotational axis line of the control shaft, and the radial direction is a radiation direction of the rotational axis line, the arm link portion being linked to the variable compression ratio mechanism of the internal combustion engine; a first housing including an accommodation chamber that accommodates the arm link portion, a radial opening portion that opens from the accommodation chamber in the radial direction, and a first opening portion that opens from the accommodation chamber toward the first journal portion side in the axial direction; and a second housing that closes the first opening portion, the second housing including a first bearing portion that supports the first journal portion.

A link component (150) with an oil hole (150E) is attached to a crankshaft (106) of an internal combustion engine (E), and the oil hole (150E) allows communication from an outside to the crankshaft (106) side. The oil hole (150E) has an inclined surface (150F) along an opening rim on the crankshaft (106) side. A surface other than the oil hole (150E) has a carbon concentration of 0.5 wt % or more. The inclined surface (150F) has a carbon concentration within a range of 0.7 wt % or more and 0.9 wt % or less. Production cost is suppressed, and at the same time, damage is prevented by increasing resistance of the oil-hole part on which stress is liable to concentrate.

A fastening structure (105) includes a pair of fastening members (105A) joined to each other, which is coupled with a bolt. The fastening member (105) is made of steel. A surface other than joint surfaces (Sa) has a Rockwell hardness of 50 HRC or more. The joint surfaces (Sa) have a Rockwell hardness of 30 HRC or more and less than 50 HRC. The joint surfaces (Sa) have an arithmetic mean roughness (Ra) of 0.2 m or more and 0.5 m or less. Production cost is suppressed, and at the same time, bending fatigue strength is secured and secondary damage due to abrasion powder generated by fretting is prevented.

Methods and systems are provided for estimating an actual compression ratio of an engine cylinder based on the electric current applied to an actuator of the associated variable compression ratio mechanism. The compression ratio is estimated as a function of both a value and a location, relative to cylinder piston position, of a peak holding current applied by an electric motor on the actuator to maintain the actuator at a commanded compression ratio setting. In this way, the vehicle control system may more accurately infer the current actual compression ratio of each cylinder.

A compression ratio varying arrangement of an engine is adapted to work with a crankshaft having at least one crankpin offset from the centerline of the crankshaft. An eccentric has an internal bore engaged with the crankpin, and an external cylindrical surface that has a centerline that is offset from the centerline of the internal bore. A connecting rod is engaged with the external cylindrical surface of the eccentric, and a piston is connected to the connecting rod. An eccentric lever is attached to the eccentric. A compression ratio adjustment link is connected to the eccentric lever. A compression ratio adjustment mechanism is connected to the compression ratio adjustment link. The compression ratio adjustment mechanism controls the orientation of the connecting rod eccentric, and thereby the compression ratio of the engine, by extending or retracting the compression ratio adjustment link.

An internal combustion engine (1) has a variable compression ratio mechanism (2) that varies a mechanical compression ratio and a variable valve timing mechanism (7) that varies a valve timing of an intake valve (4). When there is a demand to execute reference position learning (step 21) for system calibration of the variable valve timing mechanism (7), the execution of the reference position learning is permitted on the condition that the mechanical compression ratio is higher than a threshold value VCRth (step 22). When any anomaly is present in the variable compression ratio mechanism (2), the reference position learning of the variable valve timing mechanism (7) is prohibited (steps 23 and 25).

An internal combustion engine (1) has a variable compression ratio mechanism (2) that varies a mechanical compression ratio and a variable valve timing mechanism (7) that varies a valve timing of an intake valve (4). When there is a demand to execute reference position learning (step 21) for system calibration of the variable valve timing mechanism (7), the execution of the reference position learning is permitted on the condition that the mechanical compression ratio is higher than a threshold value VCRth (step 22). When any anomaly is present in the variable compression ratio mechanism (2), the reference position learning of the variable valve timing mechanism (7) is prohibited (steps 23 and 25).

A control method and a control device are provided for an internal combustion engine structured to vary a mechanical compression ratio by varying a range of slide of a piston with respect to a cylinder bore, and structured to control a flow of cooling water in a water jacket formed around the cylinder bore, wherein variation of the mechanical compression ratio causes the piston to slide on a corroded portion formed in the cylinder bore. A control process includes: acquiring a temperature correlating with a cylinder bore wall temperature; and stopping the flow of cooling water in the water jacket, in response to a condition that the acquired temperature is lower than a preset temperature point.