Evaporative fuel-processing system for internal combustion engines
First Claim
1. In an evaporative fuel-processing system for an internal combustion engine having a fuel tank, and an intake system, including a canister for adsorbing evaporative fuel generated in said fuel tank, a charging passage extending between said canister and said fuel tank, a purging passage extending between said canister and said intake system, an open-toatmosphere passage for relieving an interior of said canister to atmosphere, a charge control valve for opening and closing said charging passage, a purge control valve for opening and closing said purgingpassage, a vent shut valve for opening and closing said open-to-atmosphere passage, a pressure sensor arranged in said charging passage on a side of said charge control valve closer to said fuel tank, for detecting pressure within said charging passage, and a float valve arranged at an end of said charging passage opening into said fuel tank, the improvement comprising:
- negatively pressurizing means operable when said engine is in a predetermined operating condition, for negatively pressurizing an interior of said canister into a predetermined negatively pressurized state by opening said purge control valve and said charge control valve and closing said vent shut valve;
internal pressure-stabilizing means for stabilizing pressure within said charging passage by closing said charge control valve and said purge control valve over a predetermined time period after said negative pressurization by said negatively pressurizing means;
abnormality-determining means for opening said charge control valve when said predetermined time period has elapsed and determining abnormality of said canister, based on said pressure detected by said pressure sensor after said opening of said charge control valve; and
inhibiting means for inhibiting said abnormality determination of said canister by said abnormalitydetermining means when said pressure detected by said pressure sensor during operation of said internal pressure-stabilizing means exceeds atmospheric pressure by a predetermined amount or more.
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Accused Products
Abstract
An evaporative fuel-processing system for an internal combustion engine includes a canister, a charging passage extending between the canister and the fuel tank, a purging passage extending between the canister and the intake system of the engine, an open-to-atmosphere passage for relieving the interior of the canister to atmosphere, a charge control valve, a purge control valve, a vent shut valve, a pressure sensor for detecting pressure within the charging passage, and a float valve arranged at an end of the charging passage opening into the fuel tank. When the engine is in a predetermined operating condition, the interior of the canister is negatively pressurized into a predetermined negatively pressurized state by opening the purge control valve and the charge control valve and closing the vent shut valve. The interior of the changing passage is stabilized by closing the charge control valve and the purge control valve over a predetermined time period after the negative pressurization. When the predetermined time period has elapsed, the charge control valve is opened, and abnormality of the canister is determined based on the pressure detected by the pressure sensor after the opening of the charge control valve. When the pressure detected by the pressure sensor during the internal pressure stabilization exceeds atmospheric pressure by a predetermined amount or more, the abnormality determination of the canister is inhibited.
41 Citations
12 Claims
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1. In an evaporative fuel-processing system for an internal combustion engine having a fuel tank, and an intake system, including a canister for adsorbing evaporative fuel generated in said fuel tank, a charging passage extending between said canister and said fuel tank, a purging passage extending between said canister and said intake system, an open-toatmosphere passage for relieving an interior of said canister to atmosphere, a charge control valve for opening and closing said charging passage, a purge control valve for opening and closing said purgingpassage, a vent shut valve for opening and closing said open-to-atmosphere passage, a pressure sensor arranged in said charging passage on a side of said charge control valve closer to said fuel tank, for detecting pressure within said charging passage, and a float valve arranged at an end of said charging passage opening into said fuel tank, the improvement comprising:
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negatively pressurizing means operable when said engine is in a predetermined operating condition, for negatively pressurizing an interior of said canister into a predetermined negatively pressurized state by opening said purge control valve and said charge control valve and closing said vent shut valve; internal pressure-stabilizing means for stabilizing pressure within said charging passage by closing said charge control valve and said purge control valve over a predetermined time period after said negative pressurization by said negatively pressurizing means; abnormality-determining means for opening said charge control valve when said predetermined time period has elapsed and determining abnormality of said canister, based on said pressure detected by said pressure sensor after said opening of said charge control valve; and inhibiting means for inhibiting said abnormality determination of said canister by said abnormalitydetermining means when said pressure detected by said pressure sensor during operation of said internal pressure-stabilizing means exceeds atmospheric pressure by a predetermined amount or more. - View Dependent Claims (2, 3)
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4. In an evaporative fuel-processing system for an internal combustion engine having a fuel tank, and an intake system, including a canister for adsorbing evaporative fuel generated in said fuel tank, a charging passage extending between said canister and said fuel tank, a purging passage extending between said canister and said intake system, an open-toatmosphere passage for relieving an interior of said canister to atmosphere, a charge control valve for opening and closing said charging passage, a purge control valve for opening and closing said purging passage, a vent shut valve for opening and closing said open-to-atmosphere passage, a pressure sensor arranged in said charging passage on a side of said charge control valve closer to said fuel tank, for detecting pressure within said charging passage, a refueling charging passage for supplying evaporative fuel generated at refueling to said canister, and a valve for opening said refueling charging passage at refueling, the improvement comprising:
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negatively pressurizing means operable when said engine is in a predetermined operating condition, for negatively pressurizing an interior of said canister into a predetermined negatively pressurized state by opening said purge control valve and said charge control valve and closing said vent shut valve; internal pressure-stabilizing means for stabilizing pressure within said charging passage by closing said charge control valve and said purge control valve over a predetermined time period after said negative pressurization by said negatively pressurizing means; abnormality-determining means for opening said charge control valve when said predetermined time period has elapsed and determining abnormality of said canister, based on said pressure detected by said pressure sensor after said opening of said charge control valve; and inhibiting means for inhibiting said abnormality determination of said canister by said abnormalitydetermining means when said pressure detected by said pressure sensor during operation of said internal pressure-stabilizing means exceeds atmospheric pressure by a predetermined amount or more. - View Dependent Claims (5, 6)
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7. In an evaporative fuel-processing system for an internal combustion engine having a fuel tank, and an intake system, including a canister for adsorbing evaporative fuel generated in said fuel tank, a charging passage extending between said canister and said fuel tank, a purging passage extending between said canister and said intake system, an open-toatmosphere passage for relieving an interior of said canister to atmosphere, a charge control valve for opening and closing said charging passage, a purge control valve for opening and closing said purging passage, a vent shut valve for opening and closing said open-to-atmosphere passage, a pressure sensor arranged in said charging passage on a side of said charge control valve closer to said fuel tank, for detecting pressure within said charging passage, and a float valve arranged at an end of said charging passage opening into said fuel tank, the improvement comprising:
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negatively pressurizing means operable when said engine is in a predetermined operating condition, for negatively pressurizing an interior of said fuel tank into a predetermined negatively pressurized state by opening said purge control valve and said charge control valve and closing said vent shut-valve; negative pressurization completion-determining means for determining that said interior of said fuel tank has been brought into said predetermined negatively pressurized state, based on said pressure detected by said pressure sensor; abnormality-determining means responsive to determination of said negative pressurization completion by said negative pressurization completiondetermining means, for closing said purge control valve <
. -and said charge control valve, and determining abnormality of said fuel tank, based on said pressure detected by said pressure sensor after said closing of said purge control valve and said charge control valve; andinhibiting means for determining that said float valve closed during said negative pressurization when a rate of variation in said pressure detected by said pressure sensor has exceeded a predetermined value during operation of said negatively pressurizing means, and inhibiting said abnormality determination by said said abnormality-determining means. - View Dependent Claims (8, 9)
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10. In an evaporative fuel-processing system for an internal combustion engine having a fuel tank, and an intake system, including a canister for adsorbing evaporative fuel generated in said fuel tank, a charging passage extending between said canister and said fuel tank, a purging passage extending between said canister and said intake system, an open-to-atmosphere passage for relieving an interior of said canister to atmosphere, a charge control valve for opening and closing said charging passage, a purge control valve for opening and closing said purging passage, a vent shut valve for opening and closing said open-to-atmosphere passage, a pressure sensor arranged in said charging passage on a side of said charge control valve closer to said fuel tank, for detecting pressure within said charging passage, and a float valve arranged at an end of said charging passage opening into said fuel tank, the improvement comprising:
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negatively pressurizing means operable when said engine is in a predetermined operating condition, for negatively pressurizing an interior of said fuel tank into a predetermined negatively pressurized state by opening said purge control valve and said charge control valve and closing said vent shut valve; negative pressurization completion-determining means for determining that said interior of said fuel tank has been brought into said predetermined negatively pressurized state, based on said pressure detected by said pressure sensor; abnormality-determining means responsive to determination of said negative pressurization completion by said negative pressurization completiondetermining means, for closing said purge control valve and said charge control valve, and determining abnormality of said fuel tank, based on said pressure detected by said pressure sensor after said closing of said purge control valve and said charge control valve; and inhibiting means for determining that said float valve has been closed from a time before the start of said negative pressurization when said pressure detected by said pressure sensor has exceeded a value detected by said pressure sensor immediately before said closing of said purge control valve and said charge control valve by a predetermined amount or more within a predetermined time period after said determination of said negative pressurization completion, and inhibiting said abnormality determination by said abnormality-determining means. - View Dependent Claims (11, 12)
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Specification