Measuring and testing – With fluid pressure – Leakage
Reexamination Certificate
2000-08-10
2001-08-21
Williams, Hezron (Department: 2856)
Measuring and testing
With fluid pressure
Leakage
C073S049700, C073S118040, C123S519000
Reexamination Certificate
active
06276193
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable
MICROFICHE APPENDIX
Not Applicable
BACKGROUND OF THE INVENTION
In the manufacture of motor vehicles and particularly vehicles powered by motors burning liquid fuel such as gasoline, it has recently been required to provide an on-board diagnostic system for detecting malfunction or leakage of the fuel vapor emission control system on the vehicle.
This requirement for on-board diagnostics of the fuel vapor emission system has resulted in the need to detect fuel vapor leaks in the fuel tank, vapor storage canister and the canister purge valve and venting conduits connecting the fuel tank with the storage canister, in addition to the purge control valve connecting the canister to the engine inlet for purging fuel vapors from the storage canister to the engine during operation.
With the advent of electrically controlled fuel injectors for motor vehicle engines, it has been possible to provide electronic management of combustion in the engine with an electronic controller, which includes electrically controlling the feed of fuel vapor from a storage canister into the engine during operation. Thus, an electrically operated purge control valve on the canister has been employed.
Furthermore, requirements for minimizing the escape of fuel vapors during refueling operations; and, requirements that the vent for the vapors from the tank to the canister be closed in the event of vehicle rollover, have all created a need for valving arrangements which must be installed through openings either in the tank or the filler neck or in the lines from the tank to the storage canister. In addition, the advent of electric fuel injectors has resulted in electrically operated fuel pumps installed through an access opening in the fuel tank. Thus, the complexity of the fuel supply and vapor emission control system has resulted in numerous connections and seals which may become subject to leakage in prolonged service due to vibration and deterioration of the materials employed. Leakage has been a problem particularly where plastic materials are used which may be subject to absorption and swelling after prolonged exposure to the fuel.
Thus, it has been required to provide a way of detecting the failure of the vapor integrity of the fuel and vapor vent system or, in other words, provide the ability to detect leakage in any of the components employed in the fuel/fuel vapor emission control system. Leakage of fuel vapor under positive pressurization can also occur when the ambient conditions reach elevated temperatures particularly as may result from proximity of the fuel tank to the engine exhaust system. Leakage of atmospheric air into the fuel system can also occur as the system may be subjected to sub-atmospheric pressure resulting from cooling after prolonged usage in warm climate conditions and particularly in such conditions where the tank is normally warmed by proximity to the engine exhaust system.
Thus, it has been desired to provide a simple, relatively low cost way of detecting the presence of vapor leakage in the vehicle fuel/fuel vapor emission control system and to provide an indication of leakage in order that the vehicle operator may have the faulty condition serviced.
BRIEF SUMMARY OF THE INVENTION
The present invention solves the above-described problem of detecting leakage in the fuel vapor emission control system of a motor vehicle by providing an electrically operated diagnostic valve in the purge air inlet of the vapor storage canister employed for storing fuel vapors during periods of engine shutdown. The diagnostic test valve is electrically operated and is controlled by the electronic engine operations/emission controller and thus minimizes the cost of providing on-board diagnostic ability to detect vapor leakage in the fuel vapor emission control system.
The present invention includes a remotely actuatable diagnostic valve and a temperature sensor disposed in the tank for sensing the temperature of the fuel vapor in the tank. Following engine shutdown, the diagnostic valve biased open is remotely actuated and closed and held closed until the temperature sensor indicates that the temperature of the vapor in the tank has cooled by a predetermined amount. The diagnostic valve is then remotely de-actuated; and, if sufficient sub-atmospheric pressure (vacuum) exists in the fuel vapor due to cooling, the sub-atmospheric pressure acts on the diagnostic valve overcoming the bias to maintain the valve in a closed position. A means for detecting the valve position is provided and which provides an electrical signal to the controller indicating the presence of the sub-atmospheric pressure (vacuum) and thus the integrity of the vapor emission system is confirmed. However, if upon remote de-actuation of the diagnostic valve, the valve position detector indicates that the valve has returned to the open position under the bias of the spring, the system controller is operative to determine that leakage has occurred and provides a fault indication to the vehicle operator.
In the presently preferred practice, the diagnostic valve is solenoid operated; and, the valve position detector employs a means for electrically determining the solenoid armature/valve position either by electrically determining the inductance of the solenoid in the de-energized and energized state, or in an alternative embodiment, the solenoid armature actuates or de-actuates a switch when it is in the closed position. The present invention thus provides a unique and novel yet simple and relatively low cost technique for diagnosing the presence of leakage in the fuel vapor emission control system on a motor vehicle.
REFERENCES:
patent: 3584500 (1971-06-01), Diehl et al.
patent: 4205702 (1980-06-01), Silverwater
patent: 4512278 (1985-04-01), Winther
patent: 5054508 (1991-10-01), Benjey
patent: 5263462 (1993-11-01), Reddy
patent: 5275144 (1994-01-01), Gross
patent: 5524662 (1996-06-01), Benjey et al.
patent: 5635630 (1997-06-01), Dawson et al.
patent: 5992396 (1999-12-01), Krimmer et al.
patent: 6073487 (2000-06-01), Dawson
patent: 6182642 (2001-02-01), Ohkuma
Eaton Corporation
Garber C D
Johnson Roger A.
Williams Hezron
LandOfFree
Detecting vapor leakage in a motor vehicle fuel system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Detecting vapor leakage in a motor vehicle fuel system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Detecting vapor leakage in a motor vehicle fuel system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2544317