Abstract: A Schnuerle scavenging two-stroke engine is provided that can keep combustion stability in a wide rotation speed range while suppressing blow-by. The engine of the present invention is a Schnuerle scavenging two-stroke engine (2). A scavenging passage (14(in1)) related to at least one scavenging port (16(in1)) has, at its upper end portion (14a(in1)), an intake-side wall surface (204). The intake-side wall surface (204) defines a first flow direction (42) of scavenging gas discharged from the scavenging port (16(in1)) at a height level of the scavenging port (16(in1)). The upper end portion (14a(in1)) of the scavenging passage (14(in1)) related to the scavenging port (16(in1)) has a guide portion (50) defining a second flow direction (44) of scavenging gas discharged from the scavenging port (16(in1)). The second flow direction (44) is deflected to the intake side from the first flow direction (42) at the height level of the scavenging port (16(in1)).

Abstract: A Schnuerle scavenging two-stroke engine is provided that can keep combustion stability in a wide rotation speed range while suppressing blow-by. The engine of the present invention is a Schnuerle scavenging two-stroke engine (2). A scavenging passage (14(in1)) related to at least one scavenging port (16(in1)) has, at its upper end portion (14a(in1)), an intake-side wall surface (204). The intake-side wall surface (204) defines a first flow direction (42) of scavenging gas discharged from the scavenging port (16(in1)) at a height level of the scavenging port (16(in1)). The upper end portion (14a(in1)) of the scavenging passage (14(in1)) related to the scavenging port (16(in1)) has a guide portion (50) defining a second flow direction (44) of scavenging gas discharged from the scavenging port (16(in1)). The second flow direction (44) is deflected to the intake side from the first flow direction (42) at the height level of the scavenging port (16(in1)).

Abstract: Among multiple scavenging passages 14 included in a cylinder, a scavenging passage connected to at least one scavenging port 16 constitutes a variable scavenging passage 14(ch). An upper end portion of the variable scavenging passage 14(ch) has a guide surface 50 defining a discharge direction of a scavenging gas discharged from a variable scavenging port 16(ch) connected thereto on a horizontal plane. The guide surface 50 includes at least a first guide portion 50(H) defining a first discharge direction of the scavenging gas and a second guide portion 50(L) defining a second discharge direction of the scavenging gas. The discharge direction of the scavenging gas is changed from the first discharge direction to the second discharge direction on the horizontal plane by the first and second guide portions 50(H) and 50(L) in the scavenging stroke.

Abstract: Among multiple scavenging passages 14 included in a cylinder, a scavenging passage connected to at least one scavenging port 16 constitutes a variable scavenging passage 14(ch). An upper end portion of the variable scavenging passage 14(ch) has a guide surface 50 defining a discharge direction of a scavenging gas discharged from a variable scavenging port 16(ch) connected thereto on a horizontal plane. The guide surface 50 includes at least a first guide portion 50(H) defining a first discharge direction of the scavenging gas and a second guide portion 50(L) defining a second discharge direction of the scavenging gas. The discharge direction of the scavenging gas is changed from the first discharge direction to the second discharge direction on the horizontal plane by the first and second guide portions 50(H) and 50(L) in the scavenging stroke.

Abstract: An internal combustion engine according to the present invention has an ignition control device. When a rotational speed of the internal combustion engine increases beyond a predetermined rotational over speed, the ignition control device advances an ignition timing of the ignition plug to a first BTDC angle where proper combustion is performed. Further, the ignition control device performs a misfire stroke or strokes of the ignition plug in one rotation or rotations of the crankshaft after the proper combustion is performed by activating the ignition plug at the first BTDC angle.

Abstract: An internal combustion engine according to the present invention has an ignition control device. When a rotational speed of the internal combustion engine increases beyond a predetermined rotational over speed, the ignition control device advances an ignition timing of the ignition plug to a first BTDC angle where proper combustion is performed. Further, the ignition control device performs a misfire stroke or strokes of the ignition plug in one rotation or rotations of the crankshaft after the proper combustion is performed by activating the ignition plug at the first BTDC angle.

Abstract: In a two-stroke engine (1) according to the present invention, a piston (6) has a communication passage (28) opened to a crank chamber (10). An air intake port (30) is provided on an inner surface (2a) for causing air to flow into the communication passage (28). After a scavenging port (22) is closed by an outer surface (6a) of the piston (6) moving from the bottom dead center to the top dead center, the communication passage (28) is opened in the outer surface (6a) of the piston so as to communicate with the air intake port (30) and the scavenging port (22).

Abstract: There is provided an air cleaner that is capable of suppressing or reducing malfunctions and problems caused by mixed fuel that back flows from a carburetor, thereby prolonging filter life, reducing filter maintenance frequency, etc. The air cleaner comprises: a fuel accumulation part; and a back flow guide member that guides the mixed fuel that back flows into the air cleaner, wherein the plurality of return flow paths are provided in a radial fashion about the cleaner outlet.

Abstract: There is provided an air cleaner that is capable of suppressing or reducing malfunctions and problems caused by mixed fuel that back flows from a carburetor, thereby prolonging filter life, reducing filter maintenance frequency, etc. The air cleaner comprises: a fuel accumulation part; and a back flow guide member that guides the mixed fuel that back flows into the air cleaner, wherein the plurality of return flow paths are provided in a radial fashion about the cleaner outlet.

Abstract: In a two-stroke engine (1) according to the present invention, a piston (6) has a communication passage (28) opened to a crank chamber (10). An air intake port (30) is provided on an inner surface (2a) for causing air to flow into the communication passage (28). After a scavenging port (22) is closed by an outer surface (6a) of the piston (6) moving from the bottom dead center to the top dead center, the communication passage (28) is opened in the outer surface (6a) of the piston so as to communicate with the air intake port (30) and the scavenging port (22).