Patent ID: 6691650
Filing Date: 2004-02-17
Classification: F02B,F02F

Abstract:
A piston valve type layered scavenging 2-cycle engine (1) comprising:a cylinder (10) and a piston (30) to freely slide in an axial direction of the cylinder; a scavenging port (12), an exhaust gas port (13) and a pilot air port (14) which are open to an inner wall of the cylinder which is attached to an upper portion of a crank case (2), and which communicate with a cylinder chamber (11); an intake port (15) for an air-fuel mixture which is open to the inner wall of the cylinder, and is which communicates with a crank chamber (3); a scavenging flow passage (16) which connects the scavenging port and the crank chamber; and a position groove (34) which is provided in an outer peripheral portion of the piston and which connects the scavenging port and the pilot air port at a time of an intake stroke, wherein the scavenging port, the exhaust port, the pilot air port and the intake port are opened and closed by an upward and downward motion of the piston, a lower edge (14b) of said pilot air port is arranged at a position toward the crank chamber side displaced from an upper edge (15a) of said intake port, said piston includes an extended portion (32) extending beyond a piston lower edge (31) at a position opposing to the intake port of the cylinder, said extended portion being at a position opposing to the pilot air port of said cylinder, and the extended portion is positioned at an outer side of said piston in a direction of a crank shaft (20), and has said piston groove (34) on an outer peripheral surface thereof.