The invention relates to a method (100) for operating an internal combustion engine (2), such as an internal combustion engine of a vehicle (1), the engine (2) comprising an engine cylinder (3) at least partly defining a combustion chamber (4) and a reciprocating piston (5), a number of inlet valves (20) in fluid communication with the combustion chamber and a number of exhaust valves (30) in fluid communication with the combustion chamber, wherein any one of the inlet valves and the outlet valves comprises at least one flow control valve. The method comprises the following steps: opening (105) at least one of the inlet valves and introducing the incoming fluid medium into the cylinder (3) of the engine by performing an intake stroke (S1); compressing (110) the trapped incoming fluid medium in a first compression stroke (CS1) of the cylinder (3), while having the number of the inlet valves and the number of the exhaust valves in a closed state; injecting (115) a quantity of fuel into the cylinder (3) and combusting said injected fuel; performing (120) a first work stroke (WS1) to produce power to a crank shaft of the engine, while controlling said flow control valve to partly exhaust burnt gases at the end of the work stroke; additionally compressing (125) remaining fluid medium in an additional compression stroke (CS2) of the cylinder (3), while having the number of the inlet valves and the number of the exhaust valves in a closed state; additionally injecting (130) an additional quantity of fuel into the cylinder (3); additionally performing (135) an additional work stroke (WS2) to produce power to the crank shaft of the engine, while controlling said flow control valve to partly exhaust burnt gases at the end of the additional work stroke; and opening (180) at least one of the exhaust valves and permitting partly burnt gases to expel from the cylinder via said at least one exhaust valve by performing an exhaust stroke (ES).

Methods and systems are provided for cylinder deactivation to reduce tailpipe emissions and increase exhaust temperature. In one example, a method may include operating a first set of cylinders in a first combustion cycle over modified eight strokes and a second set of cylinders in a second combustion cycle over modified four strokes. Each cylinder in the first set of cylinders may be selectively deactivated via a variable displacement engine (VDE) mechanism while each cylinder in the second set of cylinders may be selectively deactivated via an active decompression technology (ADT) mechanism.

An actuation system for a valve is disclosed. The actuation system comprises a housing having an end wall. A first piston and a second piston is slidably positioned within the housing. The second piston is positioned between the first piston and the end wall. A piston rod is coupled to the first piston and slidably extends through the second piston and the end wall. The piston rod is configured to be coupled with the valve. A first spring is arranged between the first piston and the second piston. Further, a second spring is arranged between the second piston and the end wall. The first spring and the second spring are configured to bias the valve to a closed position.

A camshaft includes, as a cam that opens and closes an exhaust valve and an intake valve, a ball cam whose protrusion amount changes according to rotation of the camshaft, wherein the camshaft has a double structure consisting of an inner shaft and an outer shaft provided in a manner that the inner shaft is helically displaced with respect to the outer shaft around an axis of the camshaft according to a rotation speed of the camshaft, and the ball cam is accommodated movably in a guide groove provided in the inner shaft and protrudes from the outer shaft, and a protrusion amount of the ball cam from the outer shaft changes when the ball cam moves in the guide groove due to the helical displacement of the inner shaft with respect to the outer shaft.

A method is provided for operating an internal combustion piston engine, including introducing air into a cylinder of the engine, compressing the air in a first compression stroke of the cylinder, providing fuel into the cylinder for a first combustion, with a portion of the oxygen in the compressed air as oxidant, in a first power stroke succeeding the first compression stroke, to produce residues including oxygen, compressing the residues in a second compression stroke succeeding the first power stroke, and providing, after the first combustion, fuel into the cylinder for a second combustion, with at least a portion of the oxygen of the residues as oxidant, in a second power stroke succeeding the second compression stroke, wherein the first compression stroke is repealed immediately after the second power stroke, and the introduction of air into the cylinder is done at the end of the second power stroke and/or at the beginning of the first compression stroke.

In an exemplary embodiment, an internal combustion engine, in which a valve is opened and closed when a piston reciprocates in a cylinder, has a configuration to perform repeatedly the following combined strokes: an intake stroke.fwdarw.a compression stroke.fwdarw.a combustion stroke.fwdarw.an exhaust stroke in a four-cycle internal combustion engine are combined with an intake and compression stroke.fwdarw.a combustion and exhaust stroke in a two-cycle internal combustion engine. The internal combustion engine can reduce pumping loss in a six-cycle internal combustion engine and increase the output.

A camshaft includes, as a cam that opens and closes an exhaust valve and an intake valve, a ball cam whose protrusion amount changes according to rotation of the camshaft, wherein the camshaft has a double structure consisting of an inner shaft and an outer shaft provided in a manner that the inner shaft is helically displaced with respect to the outer shaft around an axis of the camshaft according to a rotation speed of the camshaft, and the ball cam is accommodated movably in a guide groove provided in the inner shaft and protrudes from the outer shaft, and a protrusion amount of the ball cam from the outer shaft changes when the ball cam moves in the guide groove due to the helical displacement of the inner shaft with respect to the outer shaft.

It is disclosed a boxer engine with two substantially mirror-symmetric engine sides (L, R) comprising a crankshaft (1) to which is connected, at least two main scotch yoke assemblies (110) each having one main piston (7) arranged inside one main cylinder (I, III; II, IV) of each engine side (R; L), and at least one auxiliary scotch yoke assembly (120) having a pair of auxiliary pistons (8) arranged inside a pair of auxiliary cylinders (V, VII; VI, VIII) of each engine side (R; L), wherein the main scotch yoke assemblies (110) are arranged synchronized on the crankshaft (1) and the at least one auxiliary scotch yoke assembly (120) is arranged 180° offset on the crankshaft (1), each auxiliary piston (7) defining an outer space and an inner space within each auxiliary cylinder (V, VII; VI, VIII), the inner space facing the opposite engine side (R; L), wherein, said inner spaces of each auxiliary cylinder (V, VII; VI, VIII) pair are in fluid communication and forming a compression chamber, said compression chamber comprises first and second check valves (69, 70), wherein the auxiliary cylinder (V, VII; VI, VIII) pair is adapted to suck in ambient air through the first check valve (69) and compress and pump said air out through the second check valve (70) into a main cylinder (I, III; II, IV) of the opposite engine side (R; L), and said outer spaces of each auxiliary cylinder (V, VII; VI, VIII) pair are in fluid communication and are receiving pressurized exhaust gas from a main cylinder (I, III; II, IV) of the same engine side (R; L).

The invention relates to a method (100) for operating an internal combustion engine (2), such as an internal combustion engine of a vehicle (1), the engine (2) comprising an engine cylinder (3) at least partly defining a combustion chamber (4) and a reciprocating piston (5), a number of inlet valves (20) in fluid communication with the combustion chamber and a number of exhaust valves (30) in fluid communication with the combustion chamber, wherein any one of the inlet valves and the outlet valves comprises at least one flow control valve. The method comprises the following steps: opening (105) at least one of the inlet valves and introducing the incoming fluid medium into the cylinder (3) of the engine by performing an intake stroke (S1); compressing (110) the trapped incoming fluid medium in a first compression stroke (CS1) of the cylinder (3), while having the number of the inlet valves and the number of the exhaust valves in a closed state; injecting (115) a quantity of fuel into the cylinder (3) and combusting said injected fuel; performing (120) a first work stroke (WS1) to produce power to a crank shaft of the engine, while controlling said flow control valve to partly exhaust burnt gases at the end of the work stroke; additionally compressing (125) remaining fluid medium in an additional compression stroke (CS2) of the cylinder (3), while having the number of the inlet valves and the number of the exhaust valves in a closed state; additionally injecting (130) an additional quantity of fuel into the cylinder (3); additionally performing (135) an additional work stroke (WS2) to produce power to the crank shaft of the engine, while controlling said flow control valve to partly exhaust burnt gases at the end of the additional work stroke; and opening (180) at least one of the exhaust valves and permitting partly burnt gases to expel from the cylinder via said at least one exhaust valve by performing an exhaust stroke (ES).

It is disclosed a boxer engine with two substantially mirror-symmetric engine sides (L, R) comprising a crankshaft (1) to which is connected, at least two main scotch yoke assemblies (110) each having one main piston (7) arranged inside one main cylinder (I, III; II, IV) of each engine side (R; L), and at least one auxiliary scotch yoke assembly (120) having a pair of auxiliary pistons (8) arranged inside a pair of auxiliary cylinders (V, VII; VI, VIII) of each engine side (R; L), wherein the main scotch yoke assemblies (110) are arranged synchronized on the crankshaft (1) and the at least one auxiliary scotch yoke assembly (120) is arranged 180° offset on the crankshaft (1), each auxiliary piston (7) defining an outer space and an inner space within each auxiliary cylinder (V, VII; VI, VIII), the inner space facing the opposite engine side (R; L), wherein, said inner spaces of each auxiliary cylinder (V, VII; VI, VIII) pair are in fluid communication and forming a compression chamber, said compression chamber comprises first and second check valves (69, 70), wherein the auxiliary cylinder (V, VII; VI, VIII) pair is adapted to suck in ambient air through the first check valve (69) and compress and pump said air out through the second check valve (70) into a main cylinder (I, III; II, IV) of the opposite engine side (R; L), and said outer spaces of each auxiliary cylinder (V, VII; VI, VIII) pair are in fluid communication and are receiving pressurized exhaust gas from a main cylinder (I, III; II, IV) of the same engine side (R; L).