An internal combustion engine (1) including a fuel reformation cylinder (2) for reforming a fuel and an output cylinder (3) for yielding an engine power by combusting a fuel or a reformed fuel, wherein at least a part of the surfaces constituting a volume-variable reaction chamber (23) of the fuel reformation cylinder (2) has a highly heat-insulative material (10).

A method for operating an engine is disclosed. The method may include supplying air from a primary air supply unit to an intake conduit. The method may also include supplying air to the engine from the intake conduit. The method may further include selectively supplying air from a secondary air supply unit to the intake conduit. In addition, the method may include maintaining an air fuel ratio between a first threshold value and a second threshold value during an increase in engine load increase by controlling a supply of air from the secondary supply unit to the intake conduit.

A fuel injection system for an engine is provided. The fuel injection system includes a fuel injector adapted to inject at least one fuel jet within a combustion chamber of the engine. The fuel injection system also includes at least one plate disposed within the combustion chamber and in association with the at least one fuel jet. The at least one plate includes at least one opening provided therein. The at least one opening is adapted to at least partially allow passage of any one of the at least one fuel jet and a flame associated with the at least one fuel jet therethrough.

An engine includes: a piston including a cavity; a cylinder head configured to form a combustion chamber having a pent roof shape; a fuel injection valve configured to inject fuel from a second half of a compression stroke until a first half of an expansion stroke; and a spark plug arranged at a position corresponding to an upper side of the cavity. Injection openings are arranged in a circumferential direction surrounding a longitudinal axis of the valve. The combustion chamber at a compression top dead center is divided into a plurality of fuel injection regions, located in respective injection directions of the injection openings, by vertical surfaces extending radially from the longitudinal axis through a middle between adjacent injection openings. When a volume of the fuel injection region located in the injection direction of the injection opening is large, an opening area of the injection opening is large.

An engine includes: a piston including a cavity; a cylinder head configured to form a combustion chamber having a pent roof shape; a fuel injection valve configured to inject fuel from a second half of a compression stroke until a first half of an expansion stroke; and a spark plug arranged at a position corresponding to an upper side of the cavity. Injection openings are arranged in a circumferential direction surrounding a longitudinal axis of the valve. The combustion chamber at a compression top dead center is divided into a plurality of fuel injection regions, located in respective injection directions of the injection openings, by vertical surfaces extending radially from the longitudinal axis through a middle between adjacent injection openings. When a volume of the fuel injection region located in the injection direction of the injection opening is large, an opening area of the injection opening is large.

An intake port of an internal combustion engine is connected to a combustion chamber and includes a connecting portion having a passage cross-sectional area that increases as the connecting portion approaches the combustion chamber, and an upstream portion connected to an upstream end of the connecting portion. The connecting portion is provided at its downstream end with a valve seat with which an umbrella part of an intake valve is brought into contact. At least one recess extending in an extending direction of the intake port and included in the connecting portion and the upstream portion is provided at least at one of two portions, the two portions located on both sides in an extending direction of an output shaft, of a peripheral surface of the intake port.

An intake port of an internal combustion engine is connected to a combustion chamber and includes a connecting portion having a passage cross-sectional area that increases as the connecting portion approaches the combustion chamber, and an upstream portion connected to an upstream end of the connecting portion. The connecting portion is provided at its downstream end with a valve seat with which an umbrella part of an intake valve is brought into contact. At least one recess extending in an extending direction of the intake port and included in the connecting portion and the upstream portion is provided at least at one of two portions, the two portions located on both sides in an extending direction of an output shaft, of a peripheral surface of the intake port.

A fuel injector assembly for an engine. The engine includes a cylinder head defining a through-hole. The fuel injector assembly includes an insert, having a first end and a second end, configured to be received within the through-hole and coupled to the cylinder head. The insert defines a bore extending from the first end to the second end. The fuel injector assembly further includes a fuel injector including a plurality of orifices, received within the bore of the insert; and a duct structure including a plurality of ducts, coupled to the insert such that the plurality of ducts align with the plurality of orifices to at least partially receive one or more fuel jets from the plurality of orifices of the fuel injector.

A ducted combustion system for an internal combustion engine includes a combustion chamber, a fuel injector, and a plurality of ducts. The combustion chamber is defined between a flame deck surface of a cylinder head and a piston crown of a piston disposed within a cylinder bore. Further, the fuel injector is configured to inject fuel into the combustion chamber as a plurality of fuel jets. The plurality of ducts is disposed within the combustion chamber between the flame deck surface and the piston crown. The plurality of ducts is disposed such that each of the plurality of fuel jets at least partially enters one of the plurality of ducts. The at least one of the plurality of ducts is configured to move to vary an angle of a corresponding at least one of the plurality of fuel jets relative to a longitudinal axis of the fuel injector.

A ducted combustion system for an internal combustion engine includes a combustion chamber, a fuel injector, and a plurality of ducts. The combustion chamber is defined between a flame deck surface of a cylinder head and a piston crown of a piston disposed within a cylinder bore. Further, the fuel injector is configured to inject fuel into the combustion chamber as a plurality of fuel jets. The plurality of ducts is disposed within the combustion chamber between the flame deck surface and the piston crown. The plurality of ducts is disposed such that each of the plurality of fuel jets at least partially enters one of the plurality of ducts. The at least one of the plurality of ducts is configured to move to vary an angle of a corresponding at least one of the plurality of fuel jets relative to a longitudinal axis of the fuel injector.