Measuring and testing – With fluid pressure – Leakage
Reexamination Certificate
2000-10-06
2001-12-11
Williams, Hezron (Department: 2856)
Measuring and testing
With fluid pressure
Leakage
C073S049200
Reexamination Certificate
active
06327898
ABSTRACT:
The present invention relates to a leakage detector, and particularly, to a leakage detector that tests the leakage integrity of components associated with vehicle fuel systems. More particularly, the present invention relates to a leakage detector having a pressure sensor that measures pressure during testing to determine whether the leakage test has been passed or failed.
Vehicle fuel systems include components such as a fuel tank, a filler neck through which the fuel tank is filled with fuel, a filler neck closure cap, a pressure-relief valve that vents fuel vapors from the fuel tank to a canister of the fuel system, and a vapor line that vents fuel vapors from the canister to the engine. The removable filler neck closure cap closes an open end of the filler neck. initally, vehicle fuel system components are designed and produced to seal properly so that, for environmental reasons, leakage of fuel vapors from the fuel system into the atmosphere is minimized.
According to the present invention, a fuel system leakage detector is provided including a pressure source providing pressurized gas, a test head adapted to be coupled to a fuel system component, a pneumatic circuit in fluid communication with the pressure source and the test head, and a pneumatic circuit bypass in fluid communication with the pressure source. The pneumatic circuit includes a measurement device and a conduit supplying pressurized gas from the pressure source to the test head. The measurement device is coupled to the conduit to detect a leakage characteristic of the fuel system component being tested. Pressurized gas is diverted into the pneumatic circuit bypass so that pressurized gas flows through the pneumatic circuit bypass and bypasses the pneumatic circuit.
According to a preferred embodiment of the present invention, the test head includes a filler neck connector adapted to couple to a filler neck of a fuel system and a cap connector adapted to couple to a closure cap of the fuel system. The measurement device includes a first indicator and a second indicator. The first indicator is in fluid communication with the filler neck connector of the test head through the conduit to detect leakage characteristics related to the fuel system being tested, The second indicator is in fluid communication with the cap connector portion of the test head through the conduit to detect leakage characteristics related to the closure cap being tested.
The fuel system leakage detector further comprises a valve. The valve is positioned to move between a first position and a second position. While in the first position, the valve blocks the flow of gas to the filler neck connector of the test head and permits the flow of gas to the cap connector of the test head during testing of the closure cap. While in the second position, the valve blocks the flow of gas to the cap connector of the test head and permits the flow of gas to the filler neck connector of the test head during testing of the remainder of the fuel system.
The pneumatic circuit further includes first and second pressure regulators. The first pressure regulator supplies gas at first pressure level to the test head. The second pressure regulator supplies gas to the test head at a second pressure level that is different than the first pressure level.
The measurement device includes a pressure bridge coupled to the pneumatic system and the signaling device. The pressure bridge includes a first passage in fluid communication with the pressure source through the pneumatic circuit, a master orifice positioned to lie in the first passage, a first control orifice positioned to lie in the first passage between the pressure source and the master orifice, a second passage in fluid communication with the test head through the pneumatic circuit, a second control orifice positioned to lie in the second passage, the sensor, and the signal generator. The sensor is coupled to the first passage at a first location between the first control orifice and the master orifice and to the second passage at a second location between the second control orifice and the test head to detect the difference in gas pressure levels extant in the first and second passage during leakage testing.
A method is provided to prepare a fuel system leakage for testing. The method includes the steps of providing a measurement device and a test head adapted to couple to a fuel system and in fluid communication with the measurement device, passing pressurized gas through the measurement device, and diverting a pressurized gas so that pressurized gas bypasses the measurement device to charge the fuel system being tested.
Additional features of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of a preferred embodiment exemplifying the best mode of carrying out the invention as presently perceived.
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Barnes & Thornburg
Garber Charles D.
Stant Manufacturing Inc.
Williams Hezron
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