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US 2004/0168656 A1Published application
Crankcase scavenged internal combustion engine
AssigneeAktiebolaget Electrolux
InventorsBo Carlsson, Mikael Bergman
Life of this patent
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AssigneeAktiebolaget Electrolux
InventorsBo Carlsson, Mikael Bergman
Estimating the term…
A crankcase scavenged internal combustion engine (1) of two-stroke type, primarily intended for a handheld working tool, such as a chain saw, with a cylinder (2) and piston (4) reciprocating along the cylinder wall (3), which piston separates a combustion chamber (5) above it and a crankcase volume (6) below it, and in the cylinder wall (3) there are ports (7, 8, 9, 10, 10′) arranged for inlet (11), exhaust outlet (12) and for a number of scavenging durct (13, 13′), whereby at least one auxiliary duct (14) is arranged with an auxiliary port (15) in the cylinder wall, which auxiliary port (15) is opened and closed by the piston, and whereby the inlet is divided into: a fuel inlet (16) leading to a fuel port (7) and an air inlet (17) leading to an air port (8), and these ports are opened and closed by the piston (4), which also comprises a transfer space (18), which mouth edges are limited by the piston periphery, and which, in at least one piston position, creates a connection between the fuel port (7) and the auxiliary duct's port (15), so that fuel can be supplied to the auxiliary durct (14) via the auxiliary port (15), and then, after the port (15) later on has been opened by the piston, can flow into the combustion chamber.
A crankcase scavenged internal combustion engine (1) of two-stroke type, primarily intended for a handheld working tool, such as a chain saw, a trimmer or a power cutter, with a cylinder (2) and a piston (4) reciprocating along the cylinder wall (3), which piston separates a combustion chamber (5) above it and a crankcase volume (6) below it, and in the cylinder wall (3) there are ports (7, 8, 9, 10, 10′) for air inlet (11), exhaust outlet (12) and for a number of scavenging ducts (13, 13′), which connect the combustion chamber with the crankcase, characterized in that at least one auxiliary duct (14) is arranged with an auxiliary port (15) in the cylinder wall, which auxiliary port (15) is opened and closed by the piston, and in that the inlet is divided into:
A crankcase scavenged internal combustion engine (1) according to any one of the preceding claims, in which the piston (4) has a penetrating piston aperture (31) located higher up axially, i.e. more far away from the crankcase than the transfer space (18) in the piston, so that air can flow into the auxiliary duct (14) and press the air/fuel-mixture (36) further down in the auxiliary duct, so that the mixture (36) begins to be scavenged later.
A crankcase scavenged internal combustion engine (1) according to any one of the preceding claims, in which a crankcase valve (26) is arranged essentially in the crankcase (6), and is controlled by the crank mechanism movement so that the auxiliary duct (14) will be throttled for optional piston positions, whereby a delayed scavenging of the air/fuel-mixture (36) is enabled—among other things.
A crankcase scavenged internal combustion engine (1) according to any one of the preceding claims, in which the auxiliary duct (14) has a length larger than 2 times the length of the respective scavenging duct (13, 13′), so that hereby the scavenging will start later in the auxiliary duct.
A crankcase scavenged internal combustion engine (1) according to any one of the preceding claims, in which the inlet is provided with at least one regulating valve (23) for enabling the amount of air and fuel flowing into the combustion engine (1) to be controlled.
A crankcase scavenged internal combustion engine (1) according to any one of the preceding claims, in which the fuel port (7) and the auxiliary duct's port (15) are located side-shifted in relation to the air port (8).
A crankcase scavenged internal combustion engine (1) according to any one of the preceding claims, in which the auxiliary duct (14) is arranged essentially outside of the cylinder (2).
A crankcase scavenged internal combustion engine (1) according to any one of the preceding claims, in which the auxiliary duct (14) is composed of a demountable, replaceable means, preferably a hose, which is mountable outside of the cylinder and having a suitable length and dimension.
A crankcase scavenged internal combustion engine (1) according to any one of the preceding claims, in which the connection between inlet (11) and auxiliary duct (14) consists of the transfer space (18) in the piston (4).
A crankcase scavenged internal combustion engine (1) according to any one of the preceding claims, having only one auxiliary duct (14).
A crankcase scavenged internal combustion engine (1) according to any one of the preceding claims, in which an extra holder (24) is arranged in connection to the auxiliary duct (14) for taking up a greater gas volume.
A crankcase scavenged internal combustion engine (1) according to any one of preceding claims, in which the auxiliary duct (14) is arranged as a connection between the cylinder (2) and the crankcase (6).
A crankcase scavenged internal combustion engine (1) according to any one of the preceding claims, having an auxiliary duct (14), which only debouches into the cylinder wall (3), so that its other end thus lacks a mouth.
A crankcase scavenged internal combustion engine (1) according to any one of the preceding claims, in which a lubricant is supplied to the system by way of a fuel duct (27) with a check valve (28) from the fuel inlet (16) to the crankcase (6).
A crankcase scavenged internal combustion engine (1) according to any one of the preceding claims, in which at least one of the connections to the fuel inlet (16), air inlet (17) and auxiliary duct to the cylinder (2) is composed of a connection (32, 32′).
A crankcase scavenged internal combustion engine (1) according to any one of the preceding claims, having at least one scavenging duct (13) arranged in the form of axial ditches along the cylinder bore (29), a so called open scavenging duct.
A crankcase scavenged internal combustion engine (1) according to any one of the preceding claims, in which the air/fuel-inlet (16) and the air inlet (17) are running parallel at least in the cylinder wall (3).
A crankcase scavenged internal combustion engine (1) according to any one of the preceding claims, in which the cylinder (2) is die-cast.
Dependencies are inferred from the claim text.