Gas-exchanging process for two-stroke, internal combustion engines
AssigneeRobert Bosch GmbH
InventorsErnst Linder, Hans Schlembach
Life of this patent
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Abstract
The invention relates to a gas-exchanging process for two-stroke internal combustion engines, and a two-stroke internal combustion engine for executing the process, in which two scavenging paths of the gas are provided, namely the known reverse scavenging as the first scavenging path, and a second supply of combustion air effected by precompression serving as the second scavenging path, wherein during the second scavenging an ignitable fuel-air mixture forms in the area of the point of ignition and, by means of the differential pressure established at the intake valve, controls the mixture as well as the quantity itself.
Claims25
A gas-exchanging process for two-stroke internal combustion engines, including a combustion chamber (1) which receives precompressed combustion air and a quantity of fuel, an engine cylinder (2), an engine piston (3), a crank case (6) and a cylinder head (4);
- with reverse scavenging in a combustion chamber, in which the engine piston controls inlet and outlet ports provided in the engine cylinder, near bottom dead center (BDC), and in which the combustion air is blown in while precompressed;
- supplying and controlling a quantity of fuel directed into the combustion chamber corresponding to the engine load, in an area of a point of ignition;
- and
- directing a second supply of precompressed combustion air into the combustion chamber controlled via an intake valve, likewise in the area of the point of ignition;
- along with reverse scavenging as a first scavenging path, this second supply of air serves as a second scavenging path of the gases in the combustion chamber, and additionally produces an ignitable fuel-air mixture in the area of the point of ignition of the combustion chamber;
- and controlling the quantity of air of the second supply of air by means of a differential pressure up- and downstream of the intake valve;
- and
- actuating the intake valve by means of said differential pressure.
A two-stroke internal combustion engine which comprises:
- at least one combustion chamber (1) defined by an engine cylinder (2), an engine piston (3) and a cylinder head (4);
- a fuel supply and fuel quantity control device (32, 37);
- at least one air compressor (6, 15, 16) for the combustion air;
- inlet and outlet ports (9, 11) in a wall of the engine cylinder (2) in an area of bottom dead center (BDC) of the engine piston (3), said inlet and outlet ports are controlled by the engine piston (3) for the first scavenging path serving as reverse scavenging and at least one additional inlet conduit of the combustion air in the cylinder head (4) that is controlled by an intake valve (22-24) loaded by the combustion chamber pressure in a closing direction;
- an intake valve of the second scavenging quantity is embodied as a control valve (22-29) including a movable valve element (22) which is loaded by at least one closing spring (27) counter to an opening direction and has a surface active in an opening direction, upstream of a valve seat (23, 24), so that the opening the intake valve is effected by a difference of the surfaces of the intake valve acting in the opening or closing direction, taking into consideration the closing spring force.
Dependencies are inferred from the claim text.