Leakage diagnosis apparatus for fuel vapor purge system and method thereof
First Claim
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1. A leakage diagnosis apparatus for a fuel vapor purge system, in which fuel vapor generated in a fuel tank is trapped in a canister via an evaporation passage, and the fuel vapor trapped in said canister is purged, via a purge passage, into an intake passage of an internal combustion engine, comprising:
- a blocking device arranged for blocking a diagnosis zone containing at least one of said fuel tank, said evaporation passage, said canister and said purge passage;
a pressure generator arranged for changing a pressure in said diagnosis zone;
a pressure detector arranged for detecting the pressure in said diagnosis zone;
a remaining quantity detector detecting a remaining fuel quantity in said fuel tank; and
a diagnosis unit that blocks said diagnosis zone by said blocking device to change the pressure in said blocked diagnosis zone by said pressure generator, and diagnoses an occurrence of leakage in said diagnosis zone based on the pressure detected by said pressure detector,wherein said diagnosis unit calculates a pressure change acceleration based on the pressure detected by said pressure detector, and diagnoses, when said pressure change acceleration is greater than a threshold, an occurrence of leakage, andwherein said diagnosis unit sets said threshold according to the remaining fuel quantity in said fuel tank when the fuel tank is contained in said diagnosis zone.
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Abstract
In a fuel vapor purge system, a blocked diagnosis zone is pressurized by an air pump, a pressure in the diagnosis zone at the time when the diagnosis zone is pressurized, and an occurrence of leakage in the diagnosis zone is judged based on the comparison between a curvature of a change curve of the pressure and a threshold.
10 Citations
21 Claims
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1. A leakage diagnosis apparatus for a fuel vapor purge system, in which fuel vapor generated in a fuel tank is trapped in a canister via an evaporation passage, and the fuel vapor trapped in said canister is purged, via a purge passage, into an intake passage of an internal combustion engine, comprising:
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a blocking device arranged for blocking a diagnosis zone containing at least one of said fuel tank, said evaporation passage, said canister and said purge passage; a pressure generator arranged for changing a pressure in said diagnosis zone; a pressure detector arranged for detecting the pressure in said diagnosis zone; a remaining quantity detector detecting a remaining fuel quantity in said fuel tank; and a diagnosis unit that blocks said diagnosis zone by said blocking device to change the pressure in said blocked diagnosis zone by said pressure generator, and diagnoses an occurrence of leakage in said diagnosis zone based on the pressure detected by said pressure detector, wherein said diagnosis unit calculates a pressure change acceleration based on the pressure detected by said pressure detector, and diagnoses, when said pressure change acceleration is greater than a threshold, an occurrence of leakage, and wherein said diagnosis unit sets said threshold according to the remaining fuel quantity in said fuel tank when the fuel tank is contained in said diagnosis zone. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A leakage diagnosis apparatus for a fuel vapor purge system, in which fuel vapor generated in a fuel tank is trapped in a canister via an evaporation passage, and the fuel vapor trapped in said canister is purged, via a purge passage, into an intake passage of an internal combustion engine, comprising:
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a blocking device blocking a diagnosis zone containing at least one of said fuel tank, said evaporation passage, said canister and said purge passage; a pressure generator changing a pressure in said diagnosis zone; a pressure detector detecting the pressure in said diagnosis zone; and a diagnosis unit that blocks said diagnosis zone by said blocking device to change the pressure in said blocked diagnosis zone by said pressure generator, and diagnoses an occurrence of leakage in said diagnosis zone based on the pressure detected by said pressure detector, wherein said diagnosis unit obtains a curvature of change curve of said pressure, and diagnoses an occurrence of leakage based on a comparison between said curvature and a threshold, and wherein, said diagnosis unit compares the pressure in said diagnosis zone with a predetermined pressure once a predetermined time elapses after a point in time at which the pressure starts to change, to determine;
(a) an existence of a leak hole having a diameter equal to or above a reference diameter when the pressure in said diagnosis zone does not reach the predetermined pressure; and
(b) an existence of a leak hole having a diameter less than the reference diameter, based on said curvature of the pressure change curve, when the pressure in said diagnosis zone reaches the predetermined pressure.
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10. A leakage diagnosis apparatus for a fuel vapor purge system, in which fuel vapor generated in a fuel tank is trapped in a canister via an evaporation passage, and the fuel vapor trapped in said canister is purged, via a purge passage, into an intake passage of an internal combustion engine, comprising:
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blocking means for blocking a diagnosis zone containing at least one of said fuel tank, said evaporation passage, said canister and said purge passage; means for changing a pressure in said blocked diagnosis zone by an external pressure generating source; means for detecting the pressure in said diagnosis zone; means for calculating a pressure change acceleration in said diagnosis zone in a state where the pressure in said diagnosis zone is being changed by said external pressure generating source; means for diagnosing an occurrence of leakage when said pressure change acceleration is greater than a threshold; means for detecting a remaining fuel quantity in said fuel tank; and means for setting said threshold according to the remaining fuel quantity in said fuel tank when the fuel tank is contained in said diagnosis zone.
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11. A leakage diagnosis method for a fuel vapor purge system, in which fuel vapor generated in a fuel tank is trapped in a canister via an evaporation passage, and the fuel vapor trapped in said canister is purged, via a purge passage, into an intake passage of an internal combustion engine, comprising the steps of:
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blocking a diagnosis zone containing at least one of said fuel tank, said evaporation passage, said canister and said purge passage; changing a pressure in said blocked diagnosis zone using an external pressure generating source; detecting the pressure in said diagnosis zone; calculating a pressure change acceleration in said diagnosis zone; diagnosing an occurrence of leakage when said pressure change acceleration is greater than a threshold; detecting a remaining fuel quantity in said fuel tank; and setting said threshold according to the remaining fuel quantity in said fuel tanks, wherein said step of blocking the diagnosis zone blocks said diagnosis zone containing said fuel tank. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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19. A leakage diagnosis method for a fuel vapor purge system, in which fuel vapor generated in a fuel tank is trapped in a canister via an evaporation passage, and the fuel vapor trapped in said canister is purged, via a purge passage, into an intake passage of an internal combustion engine, comprising the steps of:
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blocking a diagnosis zone containing at least one of said fuel tank, said evaporation passage, said canister and said purge passage; changing a pressure in said blocked diagnosis zone using an external pressure generating source; detecting the pressure in said diagnosis zone; calculating a curvature of a change curve of said detected pressure in said diagnosis zone; and diagnosing an occurrence of leakage based on a comparison of said curvature and a threshold, said step of diagnosing the occurrence of leakage comprising the steps of; measuring an elapsed time after the pressure in said diagnosis zone starts to be changed using said external pressure generating source; judging whether or not the pressure in said diagnosis zone reaches a predetermined pressure at a point of time when said elapsed time reaches a predetermined time; judging an existence of a leak hole having a diameter equal to or above a reference diameter, when the pressure in said diagnosis zone does not reach said predetermined pressure; calculating the curvature of the pressure change curve when the pressure in said diagnosis zone reaches said predetermined pressure; and judging whether or not there exists a leak hole having a diameter less than the reference diameter, based on said calculated curvature.
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20. A leakage diagnosis apparatus for a fuel vapor purge system, in which fuel vapor generated in a fuel tank is trapped in a canister via an evaporation passage, and the fuel vapor trapped in said canister is purged, via a purge passage, into an intake passage of an internal combustion engine, comprising:
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a blocking device arranged for blocking a diagnosis zone containing at least one of said fuel tank, said evaporation passage, said canister and said purge passage; a pressure generator arranged for changing a pressure in said diagnosis zone; a pressure detector arranged for detecting the pressure in said diagnosis zone; and a diagnosis unit that blocks said diagnosis zone by said blocking device to change the pressure in said blocked diagnosis zone by said pressure generator, and diagnoses an occurrence of leakage in said diagnosis zone based on the pressure detected by said pressure detector, wherein said diagnosis unit obtains a curvature of change curve of said pressure, and wherein, said diagnosis unit compares the pressure in said diagnosis zone with a predetermined pressure once a predetermined time elapses after a point in time at which the pressure starts to change, to determine;
(a) an existence of a leak hole having a diameter equal to or above a reference diameter when the pressure in said diagnosis zone does not reach the predetermined pressure; and
(b) an existence of a leak hole having a diameter less than the reference diameter, based on a comparison of said curvature of the pressure change curve and a threshold by obtaining said curvature of the pressure change curve, when the pressure in said diagnosis zone reaches the predetermined pressure.
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21. A leakage diagnosis method for a fuel vapor purge systems, in which fuel vapor generated in a fuel tank is trapped in a canister via an evaporation passage, and the fuel vapor trapped in said canister is purged, via a purge passage, into an intake passage of an internal combustion engine, comprising the steps of:
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blocking a diagnosis zone containing at least one of said fuel tank, said evaporation passage, said canister and said purge passage; changing a pressure in said blocked diagnosis zone using an external pressure generating source; detecting the pressure in said diagnosis zone; calculating a curvature of a change curve of said detected pressure in said diagnosis zone; measuring an elapsed time after the pressure in said diagnosis zone starts to be changed using said external pressure generating source; judging whether or not the pressure in said diagnosis zone reaches a predetermined pressure at a point of time when said elapsed time reaches a predetermined time; judging an existence of a leak hole having a diameter equal to or above a reference diameter, when the pressure in said diagnosis zone does not reach said predetermined pressure; calculating said curvature of the pressure change curve when the pressure in said diagnosis zone reaches said predetermined pressure; and judging whether or not there exists a leak hole having a diameter less than the reference diameter, based on said curvature of the pressure change curve.
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Specification