Evaporative fuel-processing system for internal combustion engines
First Claim
1. An evaporative fuel-processing system for an internal combustion engine having an intake system, including an evaporative emission control system having a fuel tank, a canister containing an adsorbent, said canister having an air inlet port communicatable with the atmosphere, an evaporative fuel-guiding passage extending between said canister and said fuel tank, a first control valve arranged across said evaporative fuel guiding passage, an evaporative fuel-purging passage extending between said canister and said intake system, and a second control valve arranged across said evaporative fuel-purging passage,said evaporative fuel-processing system having an abnormality-determining system in which comprises:
- pressure-detecting means for detecting pressure within said evaporative emission control system;
negatively-pressurizing means for negatively pressurizing said evaporative emission control system; and
abnormality-determining means for determining abnormality of said evaporative emission control system based on the pressure within said fuel tank detected after said evaporative emission control system has been negatively pressurized by said negatively-pressurizing means.
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Abstract
An evaporative fuel processing system adapted to be capable of detecting abnormality of an evaporative emission control system for storing, in a canister, evaporative fuel from a fuel tank for holding fuel to be supplied to an internal combustion engine, and purging evaporative fuel into the intake system of the engine. A first control valve is arranged across a passage extending between the fuel tank and the canister. A second control valve is arranged across a passage extending between the canister and the intake system of the engine. A third control valve is provided for an air inlet part of the canister communicatable with the atmosphere. Through operating these control valves to open and close them, the evaporative emission control system is negatively pressurized, and abnormality of this system is detected based on the pressure detected in this negatively pressurized state thereof. Timing for carrying out abnormality determination is determined depending on conditions of the fuel tank. Before starting the whole process for abnormality diagnosis of the system evaporative fuel stored in the canister is allowed to be purged for a predetermined time period. When the temperature of fuel in the fuel tank exceeds a predetermined value, the abnormality determination is inhibited.
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Citations
38 Claims
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1. An evaporative fuel-processing system for an internal combustion engine having an intake system, including an evaporative emission control system having a fuel tank, a canister containing an adsorbent, said canister having an air inlet port communicatable with the atmosphere, an evaporative fuel-guiding passage extending between said canister and said fuel tank, a first control valve arranged across said evaporative fuel guiding passage, an evaporative fuel-purging passage extending between said canister and said intake system, and a second control valve arranged across said evaporative fuel-purging passage,
said evaporative fuel-processing system having an abnormality-determining system in which comprises: -
pressure-detecting means for detecting pressure within said evaporative emission control system;
negatively-pressurizing means for negatively pressurizing said evaporative emission control system; and
abnormality-determining means for determining abnormality of said evaporative emission control system based on the pressure within said fuel tank detected after said evaporative emission control system has been negatively pressurized by said negatively-pressurizing means. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An evaporative fuel-processing system for an internal combustion engine having an intake system, including an evaporative emission control system having a fuel tank a canister containing an adsorbent, said canister having an air inlet port communicatable with the atmosphere, an evaporative fuel-guiding passage extending between said canister and said fuel tank, a first control valve arranged across said evaporative fuel-guiding passage, an evaporative fuel-purging passage extending between said canister and said intake system and a second control valve arranged across said evaporative fuel-purging passage,
said evaporative fuel-processing system having an abnormality-determining system which comprises: -
engine operating condition-detecting means for detecting operating conditions of said engine;
a third control valve for effecting and cutting off the communication of said air inlet port of said canister with the atmosphere;
tank internal pressure-detecting means for detecting pressure within said fuel tank;
negatively-pressurizing means for setting said evaporative emission control system to a predetermined negatively-pressurized condition by controlling said first to third control valves when it is detected by said said engine operating condition-detecting means that said engine is in operation;
a first rate of change-detecting means for detecting a rate of change in the pressure within said fuel tank caused by controlling opening and closing of said fast control valve;
a second rate of change-detecting means for detecting a rate of change in the pressure within said fuel tank caused by closing said second control valve after said negatively-pressurized condition of said evaporative emission control system has been established; and
abnormality-determining means for determining abnormality of said evaporative emission control system based on results of detection by said first and second rate of change-detecting means. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. An evaporative fuel-processing system for an internal combustion engine having an intake system, including an evaporative emission control system having a fuel tank, a canister containing an adsorbent, said canister having an air inlet port communicatable with the atmosphere, an evaporative fuel-guiding passage extending between said canister and said fuel tank, a first control valve arranged across said evaporative fuel-guiding passage, an evaporative fuel-purging passage extending between said canister and said intake system, and a second control valve arranged across said evaporative fuel-purging passage,
said evaporative fuel-processing system having an abnormality-determining system which comprises: -
engine operating condition-detecting means for detecting operating conditions of said engine, a third control valve for effecting and cutting off the communication of said air inlet port of said canister with the atmosphere, tank internal pressure-detecting means for detecting pressure within said fuel tank;
negatively-pressurizing means for setting said evaporative emission control system to a predetermined negatively-pressurized condition by controlling said first to third control valves when it is detected by said said engine operating condition-detecting means that said engine is in operation; and
abnormality-determining means for effecting a determination as to whether or not said evaporative emission control system is abnormally functioning, when a predetermined time period has elapsed during the negatively-pressurizing by said negatively-pressurizing means. - View Dependent Claims (16, 17, 18)
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19. An evaporative fuel-processing system for an internal combustion engine having an intake system, including an evaporative emission control system having a fuel tank, a canister containing an adsorbent, said canister having an air inlet port communicatable with the atmosphere, an evaporative fuel-guiding passage extending between said canister and said fuel tank, an evaporative fuel-purging passage extending between said canister and said intake system, and a purge control valve arranged across said evaporative fuel-purging passage,
said evaporative emission control system comprising: -
a drain shut valve disposed to establish and shut off communication between said air inlet port of said canister and the atmosphere;
pressure-detecting means for detecting pressure within said evaporative emission control system;
negatively-pressurizing means for negatively pressurizing said evaporative emission control system; and
abnormality-determining means for determining abnormality of said evaporative emission control system based on an extent to which the pressure is maintained within said evaporative emission control system, said extent being detected based on the pressure within said evaporative emission control system detected by said pressure-detecting means, after said evaporative emission control system has been negatively pressured by sad negatively-pressurizing means. - View Dependent Claims (20, 21, 22)
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23. In an abnormality-determining system of an evaporative fuel-processing system of a vehicle for supplying and controlling an evaporative fuel adsorbed and held in a canister to an internal combustion engine in accordance with an operating condition of the internal combustion engine, comprising an improvement wherein said abnormality determining system includes:
first engine coolant temperature determining means for determining whether engine coolant temperature is lower than a first predetermined value at an initial start-up of said internal combustion engine;
- View Dependent Claims (26, 27, 28)
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24. In an abnormality-determining system of an evaporative fuel-processing system of a vehicle for supplying and controlling an evaporative fuel adsorbed and held in a canister to an internal combustion engine in accordance with operating conditions of said internal combustion engine, comprising an improvement wherein said abnormality determining system includes:
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abnormality determining means for determining an abnormality of said evaporative fuel-processing system only when engine coolant temperature is greater than a first predetermined value; and
means for activating said abnormality-determining means at engine start-up only when said engine coolant temperature is less than a second predetermined value which is less than said first predetermined value. - View Dependent Claims (32)
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25. An abnormality-determining system for an evaporative fuel-processing system of a vehicle, the evaporative fuel-processing system including a fuel tank coupled to an intake passage of an internal combustion engine via an evaporative fuel-purging passage, a canister disposed in line with said evaporative fuel-purging passage for adsorbing and holding evaporative fuel from said fuel tank, said canister having an air inlet port for introducing outside air into said evaporative fuel-processing system, and check valve means disposed between said fuel tank and said canister for maintaining a predetermined pressure in said fuel tank, said abnormality-determining system comprising:
pressure-determining means for determining pressure within said evaporative fuel processing system;
- View Dependent Claims (29, 30, 31)
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33. An abnormality determining system for detecting an abnormality in an evaporative fuel processing system having a fuel tank storing an amount of fuel, an evaporative fuel-guiding passage extending between said fuel tank and a canister, an evaporative fuel-purging passage through which fuel vapor stored in said canister is purged into an intake passage of an internal combustion engine and a purge control valve arranged across said evaporative fuel-purging passage to allow a purge operation by opening of said purge control valve, said abnormality-determining system comprising:
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negatively-pressurizing means for introducing a negative pressure from said intake passage of said internal combustion engine into said evaporative fuel processing system;
pressure-detecting means for detecting pressure within said evaporative fuel processing system when negative pressure is introduce therein by said negatively-pressurizing means;
abnormality-determining means for determining an abnormality in said evaporative fuel processing system based upon pressure in said evaporative fuel processing system, said determination using values supplied by said pressure-detecting means; and
negative pressure controlling means for controlling said negatively-pressurizing means so as to prohibit negatively-pressurizing of said negatively-pressurizing means while said abnormality-determining means is determining the abnormality, when said negative pressure is introduced into said evaporative fuel processing system by said negatively-pressurizing means wherein suctioning of said fuel vapor collected in the fuel tank with air into the engine results in fluctuation of an air-fuel ratio. - View Dependent Claims (34)
said negatively-pressurizing means comprises controlling means for controlling said purge control valve and control valve, negative pressure inside said intake passage being introduced into said evaporative fuel processing system by closing said control valve and opening said purge control valve.
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35. An abnormality determining system for detecting an abnormality in an evaporative fuel processing system having a fuel tank storing an amount of fuel, an evaporative fuel-guiding passage extending between said fuel tank and a canister, an evaporative fuel-purging passage through which fuel vapor stored in said canister is purged into an intake passage of an internal combustion engine and a purge control valve arranged across said evaporative fuel-purging passage to allow a purge operation by opening of said purge control valve, said abnormality-determining system comprising:
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negatively-pressurizing means for introducing a negative pressure from said intake passage of said internal combustion engine into said evaporative fuel processing system;
pressure-detecting means for detecting pressure within said evaporative fuel processing system when negative pressure is introduce therein by said negatively-pressurizing means;
negative pressure controlling means for controlling said negatively-pressurizing when said negative pressure is introduced into said evaporative fuel processing system by said negatively-pressurizing means wherein suctioning of said fuel vapor collected in the fuel tank with air into the engine results in fluctuation of an air-fuel ratio; and
abnormality-determining means for determining an abnormality in said evaporative fuel processing system based upon pressure in said evaporative fuel processing system, said determination using values supplied by said pressure-detecting means, said system further comprising means for determining a fuel amount stored in said canister and said negatively-pressurizing means is activated based upon said fuel amount stored in said canister. - View Dependent Claims (36, 37, 38)
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Specification