Measuring and testing – With fluid pressure – Motor part or auxiliary
Reexamination Certificate
1999-07-14
2001-10-09
Williams, Hezron (Department: 2856)
Measuring and testing
With fluid pressure
Motor part or auxiliary
C073S040000
Reexamination Certificate
active
06298712
ABSTRACT:
TECHNICAL FIELD
The present invention relates, in general, to a testing device for a fuel or gas cap and, more particularly, to a testing device which accurately and rapidly measures the rate of leakage of air and/or fuel vapors through a fuel or gas cap and compares same against a leakage rate standard for same so that those caps with leakage rates that exceed the standard can be readily identified.
BACKGROUND ART
The testing of the functional systems of vehicles has become quite sophisticated and requires extensive test procedures to ensure that the vehicle components are operating properly and that the overall system performance is in accordance with specific guidelines. The Federal Environmental Protection Administration (EPA) has established extensive regulations limiting emissions from motor vehicles. One area of particular interest is the vehicle fuel system. The loss of fuel through evaporation to the atmosphere is wasteful and environmentally harmful since fuel vapors contribute to unwanted hydrocarbon pollution. In an effort to limit such pollution, the EPA has proposed that fuel or gas caps be pressure tested. Testing apparatus and procedures have been developed to determine the integrity of fuel caps, however, such apparatus typically involve expensive flow rate measurement devices or utilize relatively low cost measurement devices that do not yield consistent results.
In view of the foregoing, it has become desirable to develop a more cost effective and efficient apparatus and method for testing the integrity of fuel or gas caps with respect to possible leakage of air and/or fuel vapors through same.
SUMMARY OF THE INVENTION
The present invention provides an apparatus and method for testing the integrity of fuel or gas caps for leaks. As such, the present invention includes a microprocessor which allows an air pressure source to pressurize an air reservoir to a predetermined first pressure. The microprocessor then permits air within the air reservoir to pass to the fuel or gas cap under test and also through a reference orifice until a predetermined second pressure has been reached at which time an internal timer within the microprocessor is actuated. The air continues to pass to the fuel or gas cap and through the reference orifice until a predetermined third pressure has been reached at which time the elapsed time on the internal timer is stored and a solenoid valve is deactuated stopping air flow to the fuel or gas cap under test. The air from the air reservoir is then allowed to continue to pass only through the reference orifice until a predetermined fourth pressure has been reached at which time the internal timer within the microprocessor is again actuated. Air continues to flow through the reference orifice until a predetermined fifth pressure has been reached at which time the elapsed time on the internal timer is stored. By comparing the ratio of the first elapsed time (air flow to the fuel or gas cap and through the reference orifice) with the second elapsed time (air flow through the reference orifice only) against a predetermined standard ratio, a determination can be made whether air and/or vapor leakage through the fuel or gas cap exceeds an acceptable limit.
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B. T. Neyer, J. T. Adams, T. S. Stoutenborough; Aerospace Leak Test Requirements, Jul. 2000, Proceeding of 36th Joint Propulsion Conference, Huntsville, AL., pp. 1-5.
Bauman Robert L.
Docy Michael J.
Hart George R.
Garber C D
Hickok Incorporated
Hudak James A.
Williams Hezron
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