Two-cycle engine and engine tool comprising the same

A two-cycle engine comprising:

• a cylinder block having a cylinder having a top side and a bottom side between which a piston moves, said cylinder having a axial line;
• an exhaust opening, a scavenging opening formed on an inner peripheral wall of said cylinder, and an intake opening through which air-fuel mixture is introduced to said cylinder, the said cylinder defining an imaginary plane containing the axial line and passing through the exhaust opening and the intake opening;
• a scavenging passage extending in a direction of the axial line of said cylinder and connecting said scavenging opening and a crank chamber communicating with said cylinder, the air-fuel mixture flowing from the crank chamber to the scavenging opening through the scavenging passage, and flowing into the cylinder from of the scavenging opening;
• and
• an outflow direction change device provided in said scavenging passage for creating first and second outflows of the air-fuel mixture flowing out from the scavenging opening into the cylinder, the first outflow of the air-fuel mixture being created on the top side of the cylinder in the scavenging opening and the second outflow of the air-fuel mixture being created on the bottom side of the cylinder in the scavenging opening, the first outflow and the second outflow being in different directions from each other, wherein:
• the scavenging passage includes
• an upper scavenging passage connected to the scavenging opening and extending in the direction of the axial line, and
• a lower scavenging passage having a width larger than a width at a lower end of the upper scavenging passage in a circumferential direction of the cylinder when seen in the direction of the axial line of the cylinder, connected to the lower end of said upper scavenging passage, and extending toward the crank chamber in the direction of the axial line, the lower scavenging passage having an upper portion;
• and
• the outflow direction change device is configured to connect the upper scavenging passage to the lower scavenging passage in a manner that the former is shifted with respect to the latter in a direction to an inside of the lower scavenging passage and away from the exhaust opening in the circumferential direction of the cylinder, the upper scavenging passage having a center line shifted to the intake opening with respect to a center line of the lower scavenging passage when seen in a direction perpendicular to the imaginary plane, the outflow direction change device forming a step in the upper portion of the lower scavenging passage on a side close to the exhaust opening where an interior of said scavenging passages is changed stepwise.