Internal-combustion engines – Intake manifold
Reexamination Certificate
2002-02-19
2003-09-23
Yuen, Henry C. (Department: 3747)
Internal-combustion engines
Intake manifold
Reexamination Certificate
active
06622681
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a connector between a carburetor and a cylinder connection of an internal combustion engine, especially a two-stroke engine of an implement, such as a power chain saw, a brush cutter, a trimmer, or the like.
Connectors of this type conduct the fuel/air mixture produced in the carburetor to the combustion chamber of the cylinder, either directly or via the crank chamber. In so doing, a portion of the fuel is deposited on the inner wall of the connector. The fuel film that is thereby formed on the inner wall is drawn in in an uncontrolled manner, which can lead to fluctuations in speed. Especially when the engine drops down to idling after a full load phase (rich come down), there repeatedly occurs the phenomenon that the engine sticks at a higher speed and assumes a significantly higher idling speed. This is attributable to an uncontrolled supply of fuel. In particular, if after a full load phase the butterfly valve is again closed (idling position), a higher underpressure builds up in the connector that carries along the deposited residual fuel and thus prevents an orderly dropping down to the set low idling speed. This is frequently detected especially with small engines.
A connector is known from DE 36 17 759 A1 that has a structured inner wall. In this connection, the structure is formed by quadrilateral annular raised portions transverse to the axial direction of the connector. The annular raised portions are interrupted by longitudinal grooves. As a consequence of these longitudinal grooves, deposited quantities of fuel are to be conveyed to the internal combustion engine in as close to real time as possible in order to keep the residual quantity of fuel as low as possible. However, the problem of the “rich come down” effect cannot be eliminated with this configuration.
It is therefore an object of the present invention to improve a connector between the carburetor and the cylinder connection of an internal combustion engine in such a way that it is guaranteed that the internal combustion engine can drop down to the set idling speed in a manner free of disruption.
REFERENCES:
patent: 4711225 (1987-12-01), Holderle et al.
patent: 4712523 (1987-12-01), Matsubayashi
patent: 36 17 759 (1986-12-01), None
Raffenberg Michael
Trumpf Johann
Ali Hyder
Andreas Stihl AG & Co.
Becker R W
R W Becker & Associates
Yuen Henry C.
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