Internal-combustion engines – Charge forming device – Fuel flow regulation between the pump and the charge-forming...
Reexamination Certificate
2000-05-03
2001-08-28
Moulis, Thomas N. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel flow regulation between the pump and the charge-forming...
C123S518000
Reexamination Certificate
active
06279547
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to fuel vapor emission control for internal combustion engines. More particularly, the present invention relates fuel tank fuel vapor emission control for internal combustion engines.
2. Description of the Related Art
Modern transportation vehicles which employ a liquid fuel conventionally also employ for storage of the liquid fuel a fuel tank. Similarly, since most liquid fuels are highly volatile, such a fuel tank typically contains in addition to the liquid fuel a fuel vapor. A concentration of fuel in the fuel vapor within the fuel tank is generally related to a temperature of the liquid fuel within the fuel tank and a temperature of the fuel vapor within the fuel tank.
While a fuel vapor within a fuel tank does not typically impair operation of a transportation vehicle which is powered by an engine which employs a liquid fuel extracted from the fuel tank, upon refueling of the fuel tank with additional liquid fuel the fuel vapor must of necessity be displaced. For environmental protection purposes and for economic reasons, it is desirable for such displaced fuel vapor not to be released into the atmosphere.
Various apparatus, systems and methods have been disclosed within the art of fuel system design for attenuating, upon refueling of a fuel tank, release of a fuel vapor into the atmosphere. Well known in this regard are fuel system designs which incorporate the use of carbon filled fuel vapor retention canisters for cyclical absorptive capture and desorptive controlled release of a fuel vapor displaced incident to refueling of a fuel tank. Examples of such fuel system designs are disclosed within U.S. Pat. No. 4,829,968, U.S. Pat. No. 5,014,742, U.S. Pat. No. 5,054,528, U.S. Pat. No. 5,239,824, U.S. Pat. No. 5,275,145, U.S. Pat. No. 5,305,724, U.S. Pat. No. 5,456,238, U.S. Pat. No. 5,826,565, U.S. Pat. No. 5,915,364 and U.S. Pat. No. 5,934,260, all of which are incorporated herein fully by reference.
While any of the foregoing disclosed fuel system designs provides upon refueling of a fuel tank with a liquid fuel an attenuated displaced fuel vapor release into the atmosphere, such desirable result is often achieved only with complicated piping and valving schemes, or often achieved only while still encountering fuel vapor canister breathing or dissipation losses with respect to a carbon filled fuel vapor retention canister which is either open to the atmosphere or vented to the atmosphere.
There thus exists within the art of fuel system design a continuing need for comparatively simple apparatus, systems and methods for attenuating upon refueling of a fuel tank release of a displaced fuel vapor into the atmosphere.
It is towards that object that the present invention is directed.
SUMMARY OF THE INVENTION
In order to realize the object towards which the present invention is directed, the present invention provides in a first instance a fuel system comprising: (1) a fuel tank; (2) a fuel vapor tank in fluid communication with the fuel tank by means of a first fuel vapor conduit; and (3) an engine in fluid communication with the fuel vapor tank by means of a second fuel vapor conduit. The fuel system also comprises: (1) a fuel vapor pump and a first fuel vapor valve contained within the first fuel vapor conduit and interposed between the fuel tank and the fuel vapor tank; and (2) a second fuel vapor valve contained within the second fuel vapor conduit and interposed between the fuel vapor tank and the engine.
Incident to operation of the fuel system of the present invention, either: (1) when the fuel tank is being refueled and regardless whether or not the engine is operating; (2) when the engine is operating and regardless whether or not the fuel tank is being refueled; or (3) after the engine has been shut down after having been operated, the first fuel vapor valve is opened and the fuel vapor pump is energized such that a fuel vapor is extracted from the fuel tank and captured, contained and compressed within the fuel vapor tank. Similarly, incident to operation of the fuel system of the present invention, and under conditions when the engine is operating and regardless whether or not the fuel tank is being refueled, the second fuel vapor valve is opened to allow extraction of a moderated flow of fuel vapor from the fuel vapor tank into the engine.
Within the present invention, the fuel vapor tank is neither vented to, nor in fluid communication with, the atmosphere, rather, the fuel vapor tank is generally pressurized with a fuel vapor extracted from the fuel tank.
Finally, the fuel system of the present invention provides particular advantage in operation of an engine whose fuel is supplied by the fuel system of the present invention insofar as there may be employed when starting the engine only fuel vapor from the fuel vapor tank, in absence of liquid fuel from the fuel tank, such that there may be attenuated upon a cold starting of the engine incompletely combusted hydrocarbon emissions from the engine which are unlikely to be converted to less polluting exhaust gases by a catalytic convertor which has yet to achieve operating temperature.
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Crowley Thomas C.
Mancini Douglas Joseph
Pearson Thomas Edwin
Drouillard Jerome
Ford Global Technologies Inc.
Moulis Thomas N.
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