US 6,152,098 AGranted

Internal combustion engine for a portable handheld work apparatus

AssigneeAndreas Stihl AG & Co. KG

InventorsGeorg Becker, Jurgen Haberlein, Markus Husges

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Abstract

The invention is directed to an internal combustion engine for a portable handheld work apparatus. The engine includes a cylinder having a combustion chamber and a piston rotates a crankshaft via a connecting rod. The crankshaft is mounted in a crankcase and is connected to a cam drive. The cam drive drives a valve control for an inlet valve and an outlet valve. The inlet valve controls an overflow channel which leads from the crankcase to the combustion chamber, and the outlet valve controls an outlet channel branching away from the combustion chamber. Furthermore, an intake channel, which opens into the crankcase, and a housing, which is separate from the crankcase, are provided for the cam drive. In order to provide a lubrication for the cam drive which is independent of position, the cam drive is configured as a gear wheel drive and an oil sump is provided in the housing of the cam drive. At least one gear wheel of the cam drive is so arranged that it dips at least partially into the oil sump and pumps oil for lubricating the movable parts of the engine.

Claims28

Dependent claims

An internal combustion engine for a portable handheld work apparatus, said internal combustion engine comprising:

an engine housing including a cylinder and a crankcase;
a piston disposed in said cylinder so as to be movable upwardly and downwardly;
said cylinder defining a combustion chamber delimited by said piston;
said engine housing including an overflow channel leading from said crankcase into said combustion chamber and an outlet channel branching off of said combustion chamber;
a crankshaft rotatably journalled in said crankcase;
a connecting rod interconnecting said piston and said crankshaft so as to permit said piston to rotate said crankshaft;
an inlet valve for controlling said overflow channel and an outlet valve for controlling said outlet channel;
a valve control for controlling the opening and closing of said inlet and outlet valves;
a cam drive housing separate from said crankcase and defining an oil sump containing lubricating oil;
a cam drive for driving said valve control and said cam drive being a gear-wheel drive mounted in said cam drive housing;
and,
said gear-wheel drive including a plurality of gear wheels and at least one of said gear wheels being mounted in said cam drive housing so as to at least partially dip into said oil sump thereby moving oil to lubricate said cam drive as well as the movable parts of said engine including said valve control.

9 more elements

Dependencies are inferred from the claim text.