Two-cycle engine includes cylinder block formed with a cylinder and crank chamber. The cylinder block includes: an exhaust passage leading to a combustion chamber in the cylinder through an exhaust port opened to an inner circumferential surface of the cylinder; a scavenging port opened to the inner circumferential surface of the cylinder; a communication passage extending from the scavenging port in a radial direction of the cylinder; and a scavenging passage extending in an axial direction of the cylinder, communicating with the crank chamber, and having an opening portion formed in a bottom surface of the communication passage. A ceiling surface of the communication passage is inclined toward a cylinder head with increasing distance from a scavenging passage side thereof toward the scavenging port. A bottom surface of the communication passage is inclined toward the crank chamber with increasing distance from a scavenging passage side thereof toward the scavenging port.

Two-cycle engine includes cylinder block formed with a cylinder and crank chamber. The cylinder block includes: an exhaust passage leading to a combustion chamber in the cylinder through an exhaust port opened to an inner circumferential surface of the cylinder; a scavenging port opened to the inner circumferential surface of the cylinder; a communication passage extending from the scavenging port in a radial direction of the cylinder; and a scavenging passage extending in an axial direction of the cylinder, communicating with the crank chamber, and having an opening portion formed in a bottom surface of the communication passage. A ceiling surface of the communication passage is inclined toward a cylinder head with increasing distance from a scavenging passage side thereof toward the scavenging port. A bottom surface of the communication passage is inclined toward the crank chamber with increasing distance from a scavenging passage side thereof toward the scavenging port.

A two-stroke internal combustion engine includes:—a base;—a head, fixed to the base, and having a cylindrical cavity;—a piston slidable in the cylindrical cavity, to define a combustion chamber and a pumping chamber, and movable in the cylindrical cavity between a bottom and a top dead center;—a transfer duct having an inlet mouth in fluid communication with the pumping chamber, and an outlet mouth in fluid communication with the combustion chamber;—an exhaust duct having an inlet mouth in fluid communication with the combustion chamber,—a crank shaft partially housed in the pumping chamber;—a connecting rod connecting the piston to the crank shaft;—a movable partition housed inside the pumping chamber operatively connected to the crank shaft to occlude the transfer duct inlet mouth and to put in fluid communication the transfer duct inlet mouth with the pumping chamber.

A two-stroke internal combustion engine includes:—a base;—a head, fixed to the base, and having a cylindrical cavity;—a piston slidable in the cylindrical cavity, to define a combustion chamber and a pumping chamber, and movable in the cylindrical cavity between a bottom and a top dead center;—a transfer duct having an inlet mouth in fluid communication with the pumping chamber, and an outlet mouth in fluid communication with the combustion chamber;—an exhaust duct having an inlet mouth in fluid communication with the combustion chamber,—a crank shaft partially housed in the pumping chamber;—a connecting rod connecting the piston to the crank shaft;—a movable partition housed inside the pumping chamber operatively connected to the crank shaft to occlude the transfer duct inlet mouth and to put in fluid communication the transfer duct inlet mouth with the pumping chamber.

The present invention concerns a method in a two-stroke engine comprising at least one cylinder (1) with a reciprocating piston (2), a delimited combustion space (5), at least one outlet port (7) and an inlet port (9) which are both uncovered at the bottom dead center position of the piston, an actuator (8) which activates a valve (17) to open and introduce combustion air via an inlet pipe (6), a control system (15) which controls the actuator to open the valve in order to introduce combustion air via the inlet port. The invention is characterized in that the inlet port is closed by the piston after the outlet port has been closed, thus the opposite compared to the two-stroke engines of today.

With shaped connecting rod, piston and cylinder, an advantageous asymmetric timing of the two-stroke engine is achieved, wherein the combustion chamber communicates with the crankcase through a transfer port controlled by the piston and through a respective piston port controlled by the connecting rod, with the transfer port and its respective piston port arranged in series, and wherein an intake port communicates with the crankcase through a piston port controlled by the connecting rod, with the intake port and its respective piston port arranged in series.