Two-stroke internal combustion engine and engine working machine

An engine working machine, comprising a two-stroke internal combustion engine as a power source, wherein the two-stroke internal combustion engine includes:

• a cylinder, which defines a combustion chamber, and has an exhaust port;
• an ignition device configured to ignite an air-fuel mixture in the combustion chamber;
• a piston configured to reciprocate inside the cylinder through combustion and expansion that occur in the combustion chamber;
• a crank chamber communicating with an interior of the cylinder;
• a crankshaft, which is disposed in the crank chamber, and is operationally coupled to the piston;
• a fuel injection valve configured to inject a fuel into the crank chamber;
• an intake passage configured to allow only air to be sucked thereinto under a negative pressure generated when the piston is actuated;
• and
• a scavenging passage that allows communication between the crank chamber and the combustion chamber,
• wherein
• air passing through the intake passage is introduced into the scavenging passage, and air stagnant in the scavenging passage at end of air suction contributes to scavenging,
• the fuel injection valve comprises a high-pressure fuel injection valve configured to receive a fuel pressure from at least one of an electrically-driven fuel pump or a pump configured to operate through rotation of the crankshaft, and
• the fuel injection valve is configured to inject the fuel at high pressure toward an area required to be cooled in the cylinder or the crank chamber.

A two-stroke internal combustion engine, comprising:

• a cylinder, which defines a combustion chamber, and has an exhaust port;
• an ignition device configured to ignite an air-fuel mixture in the combustion chamber;
• a piston configured to reciprocate inside the cylinder through combustion and expansion that occur in the combustion chamber;
• a crank chamber communicating with an interior of the cylinder;
• a crankshaft, which is disposed in the crank chamber, and is operationally coupled to the piston;
• a fuel injection valve configured to inject a fuel into the crank chamber;
• an intake passage configured to allow only air to be sucked thereinto under a negative pressure generated when the piston is actuated;
• and
• a scavenging passage that allows communication between the crank chamber and the combustion chamber,
• wherein
• air passing through the intake passage is introduced into the scavenging passage, and air stagnant in the scavenging passage at end of air suction contributes to scavenging,
• the piston has a piston groove, and an intake port and the scavenging passage communicate with each other via the piston groove, and
• the scavenging passage has a branch passage communicating with the piston groove, and the branch passage is closer to the crank chamber than a scavenging port is.