Two-stroke, air-cooled, longitudinal scavenged petrol engine for driving portable tool, such as grass trimmer - has scavenging cylinder and outlet cylinder connected by common combustion chamber, each cylinder having piston

摘要

The engine has a first piston linearly movable forwards and backwards in a first cylinder provided with an outlet port, a second piston linearly movable forwards and backwards in a second cylinder provided with one or more scavenging ports, a common combustion chamber which joins the first and second cylinders to form a flow of fresh gas and exhaust gases in the cylinders in a direction from the scavenging ports towards the outlet ports. The cylinders and the combustion chamber form a U-section. A first, one-sidedly located crankshaft (402) is provided with a counterweight (406) and a crank pin (408) connected with the first piston and a second, one-sidedly located crankshaft (502) is provided with a counterweight (506) and a crank pin (508) connected with the second piston. The crankshafts extend parallel but in opposite directions and are reciprocally drivably connected to rotate in opposite directions.