An internal combustion engine for gaseous fuel includes a cylinder and a piston for reciprocal movement in the cylinder along a reciprocal axis, whereby a combustion chamber is at least partially delimited by the cylinder and the piston. The piston includes a piston crown facing the combustion chamber, a piston crown projection of the piston crown in a direction parallel to the reciprocal axis and onto a piston crown plane extending transversally to the reciprocal axis having a piston crown center point, the piston crown comprising a piston bowl surface defining a piston bowl and a piston rim portion enclosing the piston bowl surface. A piston bowl opening is the intersection between the piston rim portion and the piston bowl surface. The piston bowl opening has an opening center of gravity in the piston crown plane. The opening center of gravity is offset from the piston crown center point.

A fuel injection valve is provided for a ceiling portion of a cylinder head. A tip of an ignition electrode is arranged in the vicinity of an injection tip of the fuel injection valve. A recess is provided for the ceiling portion. A center of a cavity is shifted with respect to a bore center of the cylinder. In a vertical cross-section of the inside of a combustion chamber taken along a plane passing through the injection tip of the fuel injection valve and the tip of the ignition electrode, a distance from the injection tip to a wall surface of the cavity at a side at which the ignition electrode is provided is longer than a distance from the injection tip to a wall surface of the cavity at an opposite side.

A piston for use in 4 Cycle reciprocating Internal Combustion Engines. The one embodiment includes a multifunctional Engraving or Imprint that is machined into the crown of the piston. This “Imprint” consists of concentric circles of metal removed in a machining process resulting in the compartments of the functional areas within the crown of the piston connected by either the height and or cross drillings within the Imprint. The functional result is to create low and high pressure zones within the crown of the piston as it proceeds upward on the compression stroke facilitating the creation of an active moving rotational swirl in the outer 25% on the top surface area of the piston circumference. The active swirl pattern results in ultimate homogenization of the air fuel mixture leaving no area of the combustion chamber with weak or separated air and fuel molecules resulting in enhanced power and complete combustion.

A piston for use in 4 Cycle reciprocating Internal Combustion Engines. The one embodiment includes a multifunctional Engraving or Imprint that is machined into the crown of the piston. This “Imprint” consists of concentric circles of metal removed in a machining process resulting in the compartments of the functional areas within the crown of the piston connected by either the height and or cross drillings within the Imprint. The functional result is to create low and high pressure zones within the crown of the piston as it proceeds upward on the compression stroke facilitating the creation of an active moving rotational swirl in the outer 25% on the top surface area of the piston circumference. The active swirl pattern results in ultimate homogenization of the air fuel mixture leaving no area of the combustion chamber with weak or separated air and fuel molecules resulting in enhanced power and complete combustion.

A two-stroke engine piston (1) is disclosed comprising a piston top (3), a mantle surface (5), a stratified scavenging channel (7) in the mantle surface (5), and a weight reduction space (9) arranged between the piston top (3) and the stratified scavenging channel (7). The weight reduction space (9) has a largest first axial extent (a1) at the mantle surface (5) and a second axial extent (a2) radially inside the mantle surface (5), and wherein the second axial extent (a2) is greater than the largest first axial extent (a1). The present disclosure further relates to an engine (30), a hand-held tool (40), and a method of manufacturing an engine piston (1).

A two-stroke engine piston (1) is disclosed comprising a piston top (3), a mantle surface (5), a stratified scavenging channel (7) in the mantle surface (5), and a weight reduction space (9) arranged between the piston top (3) and the stratified scavenging channel (7). The weight reduction space (9) has a largest first axial extent (a1) at the mantle surface (5) and a second axial extent (a2) radially inside the mantle surface (5), and wherein the second axial extent (a2) is greater than the largest first axial extent (a1). The present disclosure further relates to an engine (30), a hand-held tool (40), and a method of manufacturing an engine piston (1).

A laminar-scavenging two-cycle engine which has a high laminar-scavenging effect, includes a scavenging passage having a crankcase side portion extending along a crankcase, and a cylinder side portion extending along a cylinder and having a length larger than the sum of the diameter and stroke of the cylinder. An ambient air introducing passage for introducing leading air into the scavenging passage is connected to an intermediate portion of the scavenging passage. A notch for opening a scavenging port to the side of the crankcase when a piston is near the top dead center is formed in the piston.

A laminar-scavenging two-cycle engine which has a high laminar-scavenging effect, includes a scavenging passage having a crankcase side portion extending along a crankcase, and a cylinder side portion extending along a cylinder and having a length larger than the sum of the diameter and stroke of the cylinder. An ambient air introducing passage for introducing leading air into the scavenging passage is connected to an intermediate portion of the scavenging passage. A notch for opening a scavenging port to the side of the crankcase when a piston is near the top dead center is formed in the piston.

A cooling channel cover for a piston of an internal combustion engine may include a body having mutually opposite end faces. At least one supply element for a coolant may be received in an opening disposed in the cooling channel cover. The supply element may include an inlet region and an outlet region, and may be held on the cooling channel cover via a clipped-in latching connection. A spring tab may be disposed on the inlet region of the supply element, and/or a latching element may be disposed on the outlet region of the supply element. The spring clip may engage one of the end faces and the latching element may engage the opposite end face.

The disclosure provides a two-cycle engine and an engine work machine. When a piston is located on the side of a bottom dead center, at a part corresponding to a notch part in the piston, an inner surface of the crank case protrudes toward an interior side to form a crank case first protruding part penetrating through the notch part toward the interior side. Meanwhile, the crank case at a part corresponding to a part without the notch part in the piston is not in a shape protruding toward the interior side. By assembling the piston and the crank case in such shapes, the piston is able to reciprocally move up and down without interfering with the crank case. In this case, by disposing the crank case first protruding part, the volume in the crank case is able to be reduced.