Air Leading-Type Stratified Scavenging Two-Stroke Internal-Combustion Engine

摘要

The certainty of supplying air to a scavenging channel through a piston groove is improved. In a cylinder wall 2, a gas venting port 10 is formed below and adjacent to a scavenging port 6a. The gas venting port 10 is independent from the scavenging port 6a, and is opened/closed by a piston as each of an air port 4a and the scavenging port 6a is. Upon a piston groove 8 being brought into communication with the gas venting port 10 as a result of the piston moving up (FIG. 1(II)), blown-back gas in a piston groove 8 can move to a crankcase through the gas venting port 10. Along with this, air can enter the piston groove 8 from the air port 4a.

主权项

1. An air leading-type stratified scavenging two-stroke internal-combustion engine comprising:
an air port that opens in a cylinder wall and is opened/closed by a piston; a scavenging channel including a scavenging port that opens in the cylinder wall and is opened/closed by the piston, the scavenging channel communicating with a crankcase; a piston groove formed in a peripheral surface of the piston, the piston groove enabling the air port and the scavenging port to communicate with each other; and a gas venting port that opens in the cylinder wall independently from the scavenging channel and is opened/closed by the piston, wherein the gas venting port is positioned on the crankcase side that is lower than the scavenging port in a cylinder axis direction, and wherein in a course of the piston moving up toward the top dead center, before the piston groove that is in communication with the air port comes into communication with the scavenging port, the piston groove that is in communication with the air port comes into communication with the gas venting port.