A two-stroke internal combustion engine has at least one cylinder (1) receiving a piston (2) and having at least one injection nozzle (4) in the form of a multi-hole low-pressure nozzle inserted in a bore (5) in the cylinder jacket (6). The multi-hole low-pressure nozzle has a nozzle plate (15) with nozzle openings (16) arranged within an enveloping circle (17) to form a common nozzle jet (11) with an opening angle (α) dependent on the inclination of the nozzle axis (12) relative to the orifice surface of the bore and preventing the nozzle jet from being applied to the cylinder jacket. A resulting vector (14) from the velocity vector (13) of the nozzle jet in the direction of the nozzle axis (12) and the velocity vector (10) of the flushing air flow in the flow main direction defines with the cylinder jacket a maximum inclination angle (γ) of 20°.

A two-stroke internal combustion engine has at least one cylinder (1) receiving a piston (2) and having at least one injection nozzle (4) in the form of a multi-hole low-pressure nozzle inserted in a bore (5) in the cylinder jacket (6). The multi-hole low-pressure nozzle has a nozzle plate (15) with nozzle openings (16) arranged within an enveloping circle (17) to form a common nozzle jet (11) with an opening angle (α) dependent on the inclination of the nozzle axis (12) relative to the orifice surface of the bore and preventing the nozzle jet from being applied to the cylinder jacket. A resulting vector (14) from the velocity vector (13) of the nozzle jet in the direction of the nozzle axis (12) and the velocity vector (10) of the flushing air flow in the flow main direction defines with the cylinder jacket a maximum inclination angle (γ) of 20°.

A cylinder structure of an internal combustion engine contains: a body, two lids, and multiple positioning elements. The body has a combustion chamber, an air inlet, an air outlet, and two scavenging units. A respective scavenging unit has a first scavenging orifice, a second scavenging orifice, a first fringe, a second fringe, a first engagement portion, and a first fixing orifice. The two lids are configured to close the first scavenging orifice and the second scavenging orifice, an air conduit is defined between a respective lid and an external fence of the body, and the respective lid has multiple second fixing orifices. A respective positioning element has a stem and at least one hook, the stem extends into the first engagement portion, and the stem is rotated so that the at least one hook contacts with the respective lid, and the respective lid is connected with the body.

A cylinder structure of an internal combustion engine contains: a body, two lids, and multiple positioning elements. The body has a combustion chamber, an air inlet, an air outlet, and two scavenging units. A respective scavenging unit has a first scavenging orifice, a second scavenging orifice, a first fringe, a second fringe, a first engagement portion, and a first fixing orifice. The two lids are configured to close the first scavenging orifice and the second scavenging orifice, an air conduit is defined between a respective lid and an external fence of the body, and the respective lid has multiple second fixing orifices. A respective positioning element has a stem and at least one hook, the stem extends into the first engagement portion, and the stem is rotated so that the at least one hook contacts with the respective lid, and the respective lid is connected with the body.

Provided is a stratified scavenging engine and a portable work machine that suppress THC sufficiently. A stratified scavenging engine includes: a cylinder having a cylinder bore; and a piston stored in the cylinder bore to be movable in a reciprocating manner. The cylinder has an intake port to intake leading air and a scavenging port to scavenge combustion gas, the intake port and the scavenging port being open to the cylinder bore. The piston has a peripheral surface including a piston groove to guide leading air from the intake port to the scavenging port, and the piston groove has a recess near the intake port.

Provided is a stratified scavenging engine and a portable work machine that suppress THC sufficiently. A stratified scavenging engine includes: a cylinder having a cylinder bore; and a piston stored in the cylinder bore to be movable in a reciprocating manner. The cylinder has an intake port to intake leading air and a scavenging port to scavenge combustion gas, the intake port and the scavenging port being open to the cylinder bore. The piston has a peripheral surface including a piston groove to guide leading air from the intake port to the scavenging port, and the piston groove has a recess near the intake port.

Provided is a stratified scavenging engine and a portable work machine that suppress THC sufficiently. A stratified scavenging engine includes: a cylinder having a cylinder bore; and a piston stored in the cylinder bore to be movable in a reciprocating manner. The cylinder has an intake port to intake leading air and a scavenging port to scavenge combustion gas, the intake port and the scavenging port being open to the cylinder bore. The piston has a peripheral surface including a piston groove to guide leading air from the intake port to the scavenging port, and the piston groove has a recess near the intake port.

Cooperatively shaped piston and cylinder head arrangements for internal combustion engines are disclosed. The piston may have a domed head with one or more curved exhaust channels and inlet channels formed therein. The piston cylinder may have curved surfaces that are exact or close inverse or negative counterparts to the curved surfaces of all or part of the domed head, including the exhaust channels, and/or inlet channels formed on the piston.

A turbomachine or a turbojet engine or a turboprop engine of an aircraft, including at least one oil circuit and a cooling mechanism including a refrigerant circuit including a first heat exchanger configured to exchange heat between the refrigerant and air and forming a condenser, a second heat exchanger configured to exchange heat between the refrigerant and the oil of the oil circuit and forming an evaporator, an expander mounted downstream from the first exchanger and upstream from the second exchanger, in a direction in which the refrigerant circulates, and a compressor mounted downstream from the second exchanger and upstream from the first exchanger.

A two-stroke internal combustion engine has at least one cylinder (1) receiving a piston (2) and having at least one injection nozzle (4) in the form of a multi-hole low-pressure nozzle inserted in a bore (5) in the cylinder jacket (6). The multi-hole low-pressure nozzle has a nozzle plate (15) with nozzle openings (16) arranged within an enveloping circle (17) to form a common nozzle jet (11) with an opening angle () dependent on the inclination of the nozzle axis (12) relative to the orifice surface of the bore and preventing the nozzle jet from being applied to the cylinder jacket. A resulting vector (14) from the velocity vector (13) of the nozzle jet in the direction of the nozzle axis (12) and the velocity vector (10) of the flushing air flow in the flow main direction defines with the cylinder jacket a maximum inclination angle () of 20.