Passage-separated intake of the present invention refers to that a separate supercharged intake passage and a separate supercharged intake supply apparatus are provided such that natural intake is separated from supercharged intake to implement respective intake without mutual interference. Time-separated intake refers to that in order to avoid a cylinder C from becoming a passage between natural intake and supercharged intake, natural intake is performed first in an intake stroke, and supercharged intake is performed after a bottom dead center of the intake stroke at the end of the natural intake. The efficiency of supercharged intake in this case is <100%. The supercharged intake is that an ECU controls the timing of intake performed by a supercharged electromagnetic gas valve V according to a signal from a crankshaft position sensor SQ. As data about a supercharged intake amount at different rotational speeds of an internal combustion engine has been input to the ECU, the ECU controls, according to a signal from a crankshaft speed sensor SR, the supercharged electromagnetic gas valve V to inject a corresponding amount of air into the cylinder C, so as to change a compression ratio by changing the supercharged intake amount.

Provided is a control device for an internal combustion engine capable of estimating a compression ratio of the internal combustion engine at the time of fuel cut of the internal combustion engine and without being affected by an intake air amount and an intake air temperature. A compression ratio is calculated on the basis of a change of in-cylinder pressure P with respect to crank angle at timing when an in-cylinder volume change rate dV/d/V takes an extreme value or at timing from closing of an intake valve 109 to the start of ignition of the air-fuel mixture in the cylinder.

Provided is a marine engine, including: a piston; and a compression ratio controller configured to execute lowering processing of moving a top dead center position of the piston toward a bottom dead center side when an engine rotation speed falls within a resonance occurrence range set in advance. A geometrical compression ratio is reduced, and a resonance stress caused by a torsional vibration in a rotary system can thus be suppressed while suppressing a decrease in thermal efficiency compared with a case in which retarding control is applied to a fuel injection timing or a closing timing of an exhaust valve.

Provided is a marine engine, including: a piston; and a compression ratio controller configured to execute lowering processing of moving a top dead center position of the piston toward a bottom dead center side when an engine rotation speed falls within a resonance occurrence range set in advance. A geometrical compression ratio is reduced, and a resonance stress caused by a torsional vibration in a rotary system can thus be suppressed while suppressing a decrease in thermal efficiency compared with a case in which retarding control is applied to a fuel injection timing or a closing timing of an exhaust valve.

A variable compression ratio device may include a connecting rod having a large end portion link-connected to a crankshaft and a small end portion link-connected to a piston by a piston pin, an eccentric cam rotatably installed at the small end portion of the connecting rod and at which the piston pin eccentrically passes through a rotation center, and an low-pressure outer plate and an high-pressure outer plate engaged with both side surfaces of the eccentric cam, formed to partially protrude outward, and selectively engaged with the connecting rod according to a compression ratio. In addition, the low-pressure outer plate and the high-pressure outer plate are selectively engaged with the connecting rod by a controller according to a supply direction of a hydraulic pressure.

When the geometric compression ratio of an engine body is set to 13:1 or more and the engine body operates in a preset high load region, the effective compression ratio of the engine body is set to 12:1 or more with a difference from the geometric compression ratio being within 2, a gas to be introduced into a combustion chamber is supercharged by a supercharging system, fuel is injected at least in a compression stroke by an injector, and after the fuel injection is finished, an air-fuel mixture in the combustion chamber is ignited by an ignition device before the compression top dead center and is thus burned by flame propagation in the engine body, and then the unburned air-fuel mixture is burned by compression ignition.

An internal combustion engine and a method of controlling an internal combustion engine are provided, that are more efficient than existing engines. The internal combustion engine includes a combustion chamber, and the engine is configurable to operate in: a compressionless operating mode where the engine is driven by combustion of fuel and oxidant in the combustion chamber without compression of the fuel and oxidant; and a compression generating operating mode where the engine is used to compress fluid in the combustion chamber.

The method of providing an internal combustion engine with one or more variable sized combustion chambers providing pistons in the cylinders forming combustion chambers, providing the pistons with piston connecting rods which are pivotably connected to the pistons on one end and to floating pins on the second end, providing crankshaft connecting rods pivotably connected to rod journals on the crankshaft and to the floating pins on a second end, and moving the position of the crankshaft relative to the cylinders such that when the position of the crankshaft relative to the cylinders is changed, the operating characteristics of the engine are changed.

The method of providing an internal combustion engine with one or more variable sized combustion chambers providing pistons in the cylinders forming combustion chambers, providing the pistons with piston connecting rods which are pivotably connected to the pistons on one end and to floating pins on the second end, providing crankshaft connecting rods pivotably connected to rod journals on the crankshaft and to the floating pins on a second end, and moving the position of the crankshaft relative to the cylinders such that when the position of the crankshaft relative to the cylinders is changed, the operating characteristics of the engine are changed.

The method of providing an internal combustion engine with one or more variable sized combustion chambers providing pistons in the cylinders forming combustion chambers, providing the pistons with piston connecting rods which are pivotably connected to the pistons on one end and to floating pins on the second end, providing crankshaft connecting rods pivotably connected to rod journals on the crankshaft and to the floating pins on a second end, and moving the position of the crankshaft relative to the cylinders such that when the position of the crankshaft relative to the cylinders is changed, the operating characteristics of the engine are changed.