When an operation state switches from a first operation region A to a second operation region B, the valve timing of an intake valve and an exhaust valve is switched upon switching of the operation state from the first operation region A to the second operation region B. When the operation state switches from the first operation region A to the second operation region B, the air-fuel ratio is switched after a first predetermined time T1 has elapsed since when the actual valve timing of the intake valve became a second intake valve timing and the actual valve timing of the exhaust valve became a second exhaust valve timing. In this way, it becomes possible to ensure ignition when the operation state switches.

A display device for an internal combustion engine includes a variable compression ratio mechanism structured to vary an engine compression ratio of the internal combustion engine. The display device includes an indicator structured to vary its indication depending on the engine compression ratio. The indicator is configured to maintain the indication constant or within a slight change with respect to a change in the engine compression ratio within each of at least one of first and second dead zones of the engine compression ratio. The first dead zone includes a vicinity of an upper limit of the engine compression ratio including the upper limit. The second dead zone includes a vicinity of a lower limit of the engine compression ratio including the lower limit.

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.

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).

Provided is a marine engine, including: an air controller configured to supply compressed air to a combustion chamber in an upstroke of a piston after a crash astern signal is output; a fuel controller configured to stop supply of fuel to the combustion chamber when the crash astern signal is output, and to resume the supply of the fuel after a backward rotation of a crankshaft; and a compression ratio controller configured to move a top dead center position of the piston toward an opposite side of a bottom dead center position of the piston when the crash astern signal is output, and the top dead center position of the piston is on the bottom dead center position side with respect to a predetermined position set in advance.

A variable compression device includes a piston rod, a first fluid chamber configured to move the piston rod in a direction in which a compression ratio is increased by supplying a pressurized working fluid thereto, a regulation member configured to regulate movement of the piston rod in a direction in which a compression ratio is increased, a second fluid chamber provided between the piston rod and the regulation member and configured to store the working fluid, a supply flow path configured to guide the working fluid supplied to the second fluid chamber, a discharge flow path configured to guide the working fluid discharged from the second fluid chamber, and a flow rate regulation unit provided in the discharge flow path and configured to regulate a flow of the working fluid when the piston rod approaches the regulation member.

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 for an internal combustion engine is arranged to vary an engine compression ratio, and includes a control mechanism arranged to control the engine compression ratio, and a driving source arranged to drive the control mechanism. The control method includes converting an operation amount of the driving source in accordance with an attenuation rate according to the engine compression ratio, transmitting the converted operation amount to the control mechanism, and controlling the cylinder pressure based on a basic ignition timing when the attenuation rate is relatively large, and controlling the cylinder pressure based on an allowable ignition timing retarded from the basic ignition timing when the attenuation rate is relatively small.

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.

A method for varying a compression ratio of an operating applied-ignition internal combustion engine having at least two cylinders and having a crank mechanism (1) comprising a crankshaft (2) which is mounted in a crankcase and which rotates at a crankshaft rotational speed .sub.crankshaft, is described. The method includes increasing an expansion phase of a cylinder cycle via rotation of the eccentric bushing (4).