Internal-combustion engines – Four-cycle – Crankcase compression of air or combustible mixture to be...
Reexamination Certificate
1999-10-28
2001-07-17
Angenbright, Tony M. (Department: 3747)
Internal-combustion engines
Four-cycle
Crankcase compression of air or combustible mixture to be...
C123S184460
Reexamination Certificate
active
06260536
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an intake passage device for an internal combustion engine.
A small agricultural machine such as a portable trimmer and a shoulder spray may be used in an inclined position. In such a machine, it is necessary that the internal combustion engine mounted on the machine operates normally even if the machine is tilted.
In general, the internal combustion engine is manufactured by molding of aluminum alloy, so that the intake passage of the engine is tapered toward the intake port of the cylinder because of the draft of the mold. As a result, the speed of the mixture flowing from the carburetor to the intake port is reduced, which may cause particles of the fuel in the mixture to drop and stick on the inside wall of the intake passage.
Japanese Utility Model Publication 3-2698 discloses a device for removing the above described problem. In the device, a connecting pipe having a constant inside passage is connected between the carburetor and the intake port, thereby forming an intake passage having a constant inner diameter over the entire length of the passage. The inner end of the connecting pipe is engaged with an inside wall of a cylindrical projection of the intake port.
However, the inside wall of the cylindrical projection has a rough surface because of the molding without grinding. Therefore, liquefied fuel is liable to enter the space between the outer wall of the connecting pipe and the rough surface and to be accumulated therein. If the accumulated fuel discharges from the space due to the position of the engine and enters the combustion chamber of the engine, the combustion condition in the chamber may be affected to discharge incomplete combustion gases, causing air pollution.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an intake passage device which may prevent the liquefied fuel from accumulating in the space between the connecting pipe and the cylindrical projection of the intake port of the cylinder of the engine.
According to the present invention, there is provided an intake passage device for an internal combustion engine having carburetor communicated with a connecting projection of an intake port of a cylinder of the engine, the device comprising, a connecting pipe communicating the carburetor with the intake port, an inner end of the connecting pipe being engaged in the connecting projection, at least one communication passage formed at a lower portion of the connecting pipe for communicating an inside of the connecting pipe with a space between an inside wall of the connecting projection and an outside wall of the connecting pipe.
The communication passage is in the form of slit in an axial direction of the connecting pipe.
In another aspect, the communication passage is in the form of cylindrical hole in a radial direction of the connecting pipe.
In still further aspect, the communication passage is in the form of a cylindrical hole in a radial direction and inclined toward the cylinder.
The device further comprises a pulse intake hole formed in an intake pipe of the carburetor for applying negative pressure pulses to a diaphragm chamber of a fuel pump.
These and other objects and features of the present invention will become more apparent from the following detailed description with reference to the accompanying drawings.
REFERENCES:
patent: 4375801 (1983-03-01), Eckman
patent: 5386145 (1995-01-01), Boswell
patent: 5572979 (1996-11-01), Czadzeck
patent: 5662077 (1997-09-01), Boswell
patent: 6065459 (2000-05-01), Stevens
Kubota Hiroshi
Watanabe Mitsunori
Angenbright Tony M.
Arent Fox Kintner & Plotkin & Kahn, PLLC
Fuji Robin Kabushiki Kaisha
Harris Katrina B.
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