STRATIFIED SCAVENGING TWO-STROKE ENGINE

摘要

An air-leading type, stratified scavenging two-stroke engine. The engine including a cylinder member and a crankcase joined therewith has an intake passage, an exhaust passage, first and second scavenging passages, a communicating portion and an air passage. The intake passage, the exhaust passage and the air passage are formed in the cylinder member. The first and the second scavenging passages each has a cylinder member-side passage and a crankcase-side passage. The cylinder member-side passages of both of the first and the second scavenging passages communicate with each other via the communicating portion. The air passage is connected to the cylinder member-side passage of the first scavenging passage. In the engine, air for pre-scavenging is introduced from the air passage through a check valve into the cylinder member-side passage of the first scavenging passage, and a part of the introduced air flows into the second scavenging passage through the communicating portion.

主权项

1. A stratified scavenging two-stroke engine including a cylinder member in which a cylinder housing a piston is formed, and a crankcase, or a crankcase-forming member forming a part of the crankcase, joined with the cylinder member, the engine comprising:
an intake passage formed in the cylinder member and that supplies a gaseous mixture of fuel and air to the inside of the crankcase; an exhaust passage formed in the cylinder member and that discharges combustion gas in the cylinder; a first scavenging passage including a cylinder member-side passage and a crankcase-side passage, and that extends from a first scavenging intake that opens to the inside of the crankcase to a first scavenging port that opens to the inside of the cylinder according to movement of the position of the piston; a second scavenging passage including a cylinder member-side passage and a crankcase-side passage, and that extends from a second scavenging intake that opens to the inside of the crankcase to a second scavenging port that opens to the inside of the cylinder according to movement of the position of the piston; a communicating portion through which the cylinder member-side passage of the first scavenging passage and the cylinder member-side passage of the second scavenging passage communicate with each other; and an air passage formed in the cylinder member and that supplies air for pre-scavenging into the cylinder member-side passage of the first scavenging passage via a check valve that opens during an upward stroke of the piston.