Internal-combustion engines – Charge forming device – Heating of combustible mixture
Reexamination Certificate
2000-06-08
2001-08-28
McMahon, Marguerite (Department: 3747)
Internal-combustion engines
Charge forming device
Heating of combustible mixture
Reexamination Certificate
active
06279549
ABSTRACT:
BACKGROUND OF THE INVENTION
I. Field of the Invention
The present invention relates to a heater for a cold start fuel injector for an internal combustion engine.
II. Description of the Prior Art
Governmental regulations restrict the maximum amount of hydrocarbon emissions as well as other emissions from an internal combustion engine. The most critical factor, however, affecting hydrocarbon emissions from an internal combustion engine occurs during the “cold start” phase of the engine start up. During the cold start phase, typically two minutes after engine ignition, the catalytic converter typically used in automotive vehicles is cold and, additionally, fuel enrichment is used to insure engine ignition. As such, during a cold start of the engine, the air/fuel ratio is much richer than stoichiometric combustion, typically 10-14:1. Furthermore, up to 50% of the hydrocarbon emissions permitted by government regulations can occur during the first 20 seconds following engine ignition.
In order to reduce hydrocarbon emissions, it is desirable to start the engine in a stoichiometric or lean state with an air/fuel ratio in the range of 14.5-16.1 depending upon the engine cylinder design and fuel composition. The spark timing is also typically retarded in order to effectively transfer heat from the combustion chamber to the catalyst in order to more quickly warm up the catalyst in the catalytic converter.
In order to provide a leaner fuel mixture during the cold start phase following engine ignition, there have been a number of previously known devices associated with cold start fuel injectors to vaporize the fuel from the cold start fuel injector prior to its induction into the engine cylinder. Vaporization of the fuel from the cold start fuel injector, of course, enables a leaner air/fuel mixture to be inducted into the engine cylinders while still insuring engine ignition during a cold start condition. However, these previously known heaters have not proven wholly satisfactory in operation.
SUMMARY OF THE PRESENT INVENTION
The present invention provides a heater for use with a fuel passageway for an internal combustion engine, such as a cold start fuel passageway, which overcomes the above-mentioned disadvantages of the previously known devices.
In brief, the heater of the present invention comprises a tubular housing which is insertable into the passageway. The tubular housing is inserted into the passageway so that fuel flow through the passageway flows through the interior of the tubular housing.
The heater of the present invention further comprises a plurality of heating assemblies wherein each heating assembly includes a capsule and at least one electrical heating element thermally coupled to its associated capsule. In the preferred embodiment of the invention, the heating element comprises a PTC ceramic material although other materials may optionally be used.
The capsules are then secured to the housing so that the capsules are circumferentially spaced from each other around the housing. In one embodiment, the capsules are secured to an interior surface of the tubular housing so that at least one surface of the capsule is open to the interior of the tubular housing. Thus, upon activation of the heating elements, the heating elements heat the surface of the capsule exposed to the interior of the tubular housing thus heating and vaporizing any fuel flow through the tubular housing.
In a further embodiment of the invention, the capsules are secured around the outer periphery of the housing so that the capsules are circumferentially spaced from each other. In this embodiment of the invention, one surface of each heating element is thermally coupled to the housing. Consequently, upon activation or energization of the heating elements, the heating elements heat the housing thus heating and vaporizing any fuel flow through the housing.
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Hunt Frank W.
Oho Shigeru
Gifford, Krass, Groh Sprinkle, Anderson & Citkowski, P.C.
Hitachi America Ltd.
McMahon Marguerite
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