US 2001/0032602 A1Published application

Die cast metal cylinder assembly for a two-stroke engine

AssigneeAndreas Stihl AG & Co. KG

InventorsLars Bergmann, Heiko Rosskamp, Iqor Klaric, Michael Raffenberg, Peter Pretzsch

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Abstract

The invention relates to a cylinder which can be produced of die cast metal. The cylinder is for a two-stroke engine in a portable handheld work apparatus such as a motor chain saw. A combustion chamber (3) is formed in the cylinder (2) and this combustion chamber is delimited by a piston (5). In the cylinder wall (16), there is an outlet (10) for conducting away the combustion gases from the combustion chamber (3). Furthermore, transfer channels (14a, 14b) are provided which open into the combustion chamber (3) via transfer windows (12, 15) and supply the operating medium from the crankcase (4) needed for operating the two-stroke engine. The transfer channels (14a, 14b) are configured in the cylinder wall (16) as channels opening radially to the outside. These channels are closed by a seated cover (23). In order to provide a cylinder which can be manufactured simply as die cast part, it is provided that the frame surfaces (31, 41) of the first and second transfer windows (12, 15) are arranged in mutually parallel pull planes (39, 49). The frame surfaces run approximately parallel to the cylinder axis (17) and lie in the peripheral direction of the cylinder bore facing to the outlet (10).

Claims12

Dependent claims

A cylinder assembly for a two-stroke engine including an engine for a portable handheld work apparatus including a chain saw, brushcutter, cutoff machine or the like, the two-stroke engine including a piston, the cylinder assembly comprising:

a cylinder having a cylinder wall defining a cylinder bore surface and a cylinder axis;
said cylinder wall and said piston conjointly delimiting a combustion chamber in said engine;
an outlet formed in said cylinder wall for conducting combustion gases away from said combustion chamber;
a plurality of transfer channels for conducting operating means to said combustion chamber for operating said engine;
a first one of said transfer channels having a first transfer window opening into said combustion chamber near said outlet to form an outlet-near transfer window;
a second one of said transfer channels having a second transfer window opening into said combustion chamber remote from said outlet to form an outlet-remote transfer window;
said first and second transfer channels being open channels directed radially outwardly;
a cover mounted on said cylinder to cover said channels;
said first and second windows having respective outlet-remote frame surfaces extending approximately parallel to said cylinder axis and facing toward said outlet viewed in the peripheral direction of said cylinder bore surface;
and,
said outlet-remote frame surfaces lying in respective mutually parallel pull planes.

8 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/829,902Filed 11 Apr 2001
Priority: DE 100 19 983.622 Apr 2000
Published: 25 Oct 2001
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

F02B 25/14
Engines characterised by using fresh charge for scavenging cylinders: using reverse-flow scavenging, e.g. with both outlet and inlet ports…
F02B 33/04
Engines with reciprocating-piston pumps; Engines with crankcase pumps: with simple crankcase pumps, i.e. with the rear face of a non-stepped…
F02B 63/02
Adaptations of engines for driving pumps, hand-held tools or electric generators; Portable combinations of engines with engine-driven devices: for…
F02F 1/22
Other cylinders: characterised by having ports in cylinder wall for scavenging or charging