Internal-combustion engines – Cooling – Air-cooled
Reexamination Certificate
1999-11-17
2001-08-14
Kamen, Noah P. (Department: 3747)
Internal-combustion engines
Cooling
Air-cooled
C123S540000
Reexamination Certificate
active
06273035
ABSTRACT:
TECHNICAL FIELD
This invention relates to heat sinks for internal combustion engine induction systems, and more particularly, to heat sinks for a single cylinder air cooled engine.
BACKGROUND ART
Small engines, particularly small single cylinder air cooled spark ignited engines used in portable or operator carried power tools, are typically very compact and have the fuel metering device such as a carburetor or injector located in close proximity to the engine block. When these engines are shut down, the forced air cooling caused by the engine fan stops. As the engine cools in this post shut down soak period, the fuel metering device tends to initially rise in temperature before subsequently, gradually cooling off. This temperature rise particularly when fuel metering devices in close thermal proximity to the engine block can cause the fuel metering device such as a carburetor or the like, to become so hot that the residual fuel contained therein boils out. This fuel loss not only contributes to evaporative emissions, but can make the engine difficult to restart.
DISCLOSURE OF INVENTION
Accordingly, it is an object of the present invention to provide a single cylinder air cooled spark ignited engine having an improved induction system which limits the peak temperature of the fuel metering device during the post engine shut down soak.
It is a further object of the present invention to provide an induction system which maintains post shut down peak temperature of the engine fuel metering device to below 130° F. while maintaining a compact engine configuration.
Accordingly, a single cylinder air cooled spark ignition engine is provided with an engine block having an intake port for receiving an air fuel mixture to be burned. A tubular non-metallic intake runner is provided between the engine block and the air fuel metering device which supplies a mixture of air and fuel to the engine block intake port. A first baffle of thin sheet metal material is affixed to the air metering device inlet. A second baffle formed of thin sheet metal material is interposed between the air metering device and the tubular runner so that the first and second baffles absorb heat and dissipate the heat to the atmosphere when the engine is shut off. The baffles are of sufficient size so that after running the engine at a hot equilibrium state in a 70° F. atmosphere, the baffles limit the peak temperature of the fuel within the air fuel metering device to 130° F.
REFERENCES:
patent: 4218406 (1980-08-01), Detweiler
patent: 4356806 (1982-11-01), Freesh
patent: 4414163 (1983-11-01), Barr et al.
patent: 4739732 (1988-04-01), Nakamura et al.
patent: 5699761 (1997-12-01), Yamaguchi et al.
patent: 5803035 (1998-09-01), Guntly
Gest William E.
Jankowski Mark D.
Smith Clyde J.
Brooks & Kushman P.C.
Kamen Noah P.
MTD Products Inc.
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