An internal combustion engine includes a crankshaft and at least one piston coupled to the crankshaft for executing strokes in a cylinder as a result of rotation of the crankshaft. An eccentric shaft is coupled to the crankshaft and to the piston in such a way that strokes of the piston are adjusted by the eccentric shaft. A phase adjuster adjusts a phase of the coupling of the eccentric shaft to the crankshaft.

A bearing structure has a crankshaft rotatably supported by a crankshaft bearing part, formed of a cylinder block of an internal combustion engine and a first bearing cap, through a bearing metal, a second shaft rotatably supported by a second shaft bearing part formed of the first bearing cap and a second bearing cap, wherein the bearing metal has a bearing metal planar portion for rotatably supporting the crankshaft with an entire inner peripheral surface of the bearing metal, the inner peripheral surface at which the bearing metal planar portion is formed, a bearing metal oil groove portion formed with an oil groove formed to extend circumferentially in an inner peripheral surface of the bearing metal, the inner peripheral surface at which the bearing metal oil groove portion is formed, a first oil hole opening at the oil groove, and a second oil hole opening at the oil groove.

A variable compression ratio internal combustion engine is equipped with a variable compression ratio mechanism that changes an engine compression ratio depending on the rotational position of a first control shaft arranged in an oil pan, and an actuator that changes and holds the rotational position of the first control shaft, and a linking mechanism configured to link the actuator and the first control shaft. The linking mechanism has a lever linked to the first control shaft, and a connecting pin configured to rotatably link the tip of an arm part extending radially outward from the center of the first control shaft and one end of the lever. At least when having been set to the highest compression ratio, the first connecting pin is configured to be submerged below an oil level of the oil pan.

A set of mechanisms, for use with an internal combustion test engine, for testing cylinder offset during operation of the engine. The test engine specifics may vary, but it is assumed to have a crankcase base that supports a cylinder barrel and cylinder head. During engine operation, a transit plate is secured to the top surface of the crankshaft base, and a pair of wedge plates is secured between the transit plate and the bottom of the cylinder barrel. When the engine is not in operation, the transit plate can be slid in a direction normal to the crankshaft axis (for cylinder offset adjustment), and the wedge plates can be moved relative to each other (for cylinder height adjustment).

Various embodiments provide a method of varying engine displacement. The method includes determining a change in a stroke distance of the engine required to obtain a pre-determined volumetric change in a displacement of the engine. The method includes machining a top surface of a crankcase so as to remove a height of material from the crankcase. The height is calculated to correspond to the change in the stroke of the engine required to obtain the volumetric change in the displacement of the engine. The method also includes coupling the crankcase to an engine block portion of the engine.

Provided is a crosshead engine that includes: a cylinder; a piston; a piston rod; a crosshead; a connecting rod; a crankshaft; and a variable mechanism varies positions of top and bottom dead centers of the piston by changing a relative position between the piston rod and the crosshead in a stroke direction of the piston. The variable mechanism includes: a hydraulic pressure chamber which is provided in the crosshead and into which an end of the piston rod is inserted; and a hydraulic pressure adjustment mechanism which supplies hydraulic oil to the hydraulic pressure chamber or discharges the hydraulic oil from the hydraulic pressure chamber and which adjusts an entering position at which the end of the piston rod is inserted into the hydraulic pressure chamber in the stroke direction.

A variable compression ratio device is configured to be incorporated into an internal combustion engine. The internal combustion engine includes one or more cylinders housing pistons that are coupled to a crankshaft. The variable compression ratio device includes a rotation coupler assembly formed by gears that have internal and external teeth, the rotation coupler assembly being disposed at a distal end of the crankshaft to cause the crankshaft to rotate. Translation variations of the crankshaft are to be converted into rotation and transmitted to at least one of a toothed gear or a flange of a flywheel.

A rotation coupler for an internal combustion engine includes a ring gear configured to rotate about a first axis. The rotation coupler further includes an input pinion gear configured to transfer rotation of a crankshaft of the internal combustion engine to the ring gear to cause the ring gear to rotate about the first axis. The input pinion gear is eccentrically movable relative to the first axis. The rotation coupler further includes an output pinion gear configured to transfer rotation of the ring gear about the first axis to a flywheel of the internal combustion engine.

In a variable compression ratio engine according to the present invention, an eccentric sleeve is installed on a crankpin, and an effective length of a connecting rod is changed by adjusting a posture of an eccentric sleeve relative to the connecting rod, or an effective length of a crank arm is changed by adjusting a posture of an eccentric sleeve relative to the crank arm. An eccentric sleeve control shaft installed on a main journal or one shaft of a planetary gear system is connected to an eccentric sleeve by means of an eccentric sleeve auxiliary shaft. Automatic adjustment of the compression ratio based on crankshaft rotation speed may be achieved using a rotor, a stator, or a rack.