Fluent material handling – with receiver or receiver coacting mea – Automatic control of flow cutoff or diversion – Level or overflow responsive
Reexamination Certificate
2000-05-16
2001-03-27
Jacyna, J. Casimer (Department: 3751)
Fluent material handling, with receiver or receiver coacting mea
Automatic control of flow cutoff or diversion
Level or overflow responsive
C141S059000, C141S044000, C141S046000, C141S302000, C137S043000, C137S202000
Reexamination Certificate
active
06206057
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to control values for “onboard” type fuel vapor recovery systems for vehicle fuel tanks, wherein fuel vapor generated during the refueling process is vented to onboard vapor recovery apparatus such as a carbon canister.
BACKGROUND OF THE INVENTION
Systems for controlling the flow of fuel vapor from a vehicle fuel tank to a recovery apparatus such as a carbon canister are generally known. A common approach is to place a control valve in series between the fuel tank and the vapor trap to selectively open and close the vapor venting pathway in response to changes in vehicle refueling activity.
Some known vapor control valves open or close in response to pressure conditions at the filler pipe inlet, for example when a filler pipe cap is removed or replaced to indicate the start or finish of refueling operations.
Other pressure-operated control valves respond to vapor pressure in the fuel tank itself to open, close, or adjust the rate at which fuel vapor is vented.
Another known type of valve responds to the level of liquid fuel in the tank, staying open to vent vapor as long as the fuel level is below a predetermined level. These are sometimes referred to as “fill control” or “shutoff” valves, since their closing creates a sudden pressure increase in the tank which prevents further refueling.
Prior vapor recovery systems often use pressure-operated control valves, sometimes supplemented with rollover and/or fill control valves to supplement the pressure operated vapor control. Disadvantages of such pressure-operated systems include their relative complexity and cost; their sensitivity to changing pressure conditions in the fuel system; and, the need for vapor seal and/or signal structure in the filler pipe, for example filler nozzle trap doors and signal pressure lines to prevent the loss of fuel vapor to the atmosphere during refueling and/or to provide signal or actuation pressure to the control valve.
One known technique for eliminating filler nozzle trap door or other seal structure in the filler pipe is to create a “dynamic” seal in the pipe using only the flow effects of a high velocity stream of fuel from the filler nozzle. By properly shaping the filler pipe in the region where the filler nozzle is located during refueling, and pumping the fuel at high velocity, a vacuum or draw-type seal can be created and maintained around the filler nozzle during refueling. This eliminates the need for seal door and similar structure. However, many pressure-operated control valves cannot function without such structure in the filler pipe. The dynamic sealing generates higher refueling pressure in the tank, tending to cause undesirable fuel expulsion or “spitback” from the filler pipe inlet at the end of the refueling operation. The prior art has not adequately addressed the need for an onboard vapor recovery system suitable for high pressure refueling with a dynamic filler pipe seal.
SUMMARY OF THE INVENTION
The system preferably includes bleed means such that the head pressure is only temporarily maintained when the system is closed, for example long enough to prevent further refueling attempts immediately after the tank has been filled. The head valve can incorporate the bleed means, and preferably includes rollover valve means.
The fuel level responsive control valve comprises a two-stage shutoff valve with a cushioned, “soft” initial shutoff for the high pressure refueling operation. In one embodiment the control valve includes primary and secondary venting ports successively closed by first and second valve structure at first and second fuel levels. In alternate embodiments, the shutoff valve can comprise a coaxial shutoff valve, or an offset shutoff valve with radially offset primary and secondary vent ports and associated valve structure.
These and other features of the invention will become apparent upon further reading of the specification.
REFERENCES:
patent: 3915184 (1975-10-01), Galles
patent: 5014742 (1991-05-01), Covert et al.
patent: 5028244 (1991-07-01), Szlaga
patent: 5044389 (1991-09-01), Gimby
patent: 5215132 (1993-06-01), Kobayashi
patent: 5322099 (1994-06-01), Langlois
patent: 5449029 (1995-09-01), Harris
Benjey Robert P.
Bergsma Rudolph
G. T. Products, Inc.
Jacyna J. Casimer
Young & Basile P.C.
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