Patent Number: 6,167,874

Title: Portable handheld work apparatus having a four-stroke engine

Abstract: The invention relates to a motor-driven chain saw having an internal combustion engine for driving the saw chain of the chain saw. The engine is mounted in the housing of the chain saw and includes a cylinder and a combustion chamber formed in the cylinder. The combustion chamber is delimited by a piston and the piston drives a crankshaft via a connecting rod. The crankshaft is rotatably journalled in a crankcase. An inlet and an outlet are provided for gas exchange in the combustion chamber and the inlet is connected via an intake channel to a mixture preparation device. A stroke/bore ratio of less than 0.8 is used in order to provide an engine of reduced structural elevation which is useable in all positions. The inlet and outlet are controlled via valves having a valve drive charged with the air/fuel lubricating oil mixture supplied via the mixture preparation device.

Inventors: Becker; Georg (Schwaikheim, DE), Haberlein; Jurgen (Murrhardt, DE)

Assignee: Andreas Stihl AG & Co.

International Classification: F01M 9/00 (20060101); F01M 9/10 (20060101); F01M 1/00 (20060101); F01M 1/04 (20060101); F02B 63/02 (20060101); F02B 63/00 (20060101); F02B 75/02 (20060101); F02B 025/06 ()

Expiration Date: 01/02/2018