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Evaporative fuel-processing system for internal combustion engines

Inactive Publication Date: 2002-10-29
HONDA MOTOR CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

It is the object of the invention to provide an evaporative fuel-processing system for an internal combustion engine, which is capable of detecting abnormality of

Problems solved by technology

However, the above abnormality diagnosis method using the air-fuel ratio correction coefficient suffers from a problem that in the case where a leak of evaporative fuel occurs from defective seals provided at piping connections, valves, the fuel tank, etc. of the system, (e.g. a seal at a filler cap of the fuel tank), it is impossible to detect the leak by the above method, which can result in emission of a large amount of evaporative fuel into the air.

Method used

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  • Evaporative fuel-processing system for internal combustion engines

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first embodiment

FIG. 6 shows a program for carrying out the abnormality diagnosis of the evaporative emission control system 11, which is executed by the ECU 5 of the evaporative fuel-processing system according to the invention. This program is executed as background processing.

First, at a step S21, it is determined whether or not the flag FMON has been set to "1" in the monitoring condition-determining routine described above with reference to FIG. 5. Immediately after the engine 1 has been started, the monitoring conditions are not satisfied, and hence the answer to the question of the step S21 is negative (NO), so that the program proceeds to a step S22, where a first timer tmPTO, formed of a down-counter, is set to a predetermined time period T1, and started. The first timer tmPTO is provided to secure a sufficient time period for stabilizing the tank internal pressure PT after the tank internal pressure PT is relieved to the atmosphere, and accordingly the predetermined time period T1 assumes...

second embodiment

FIG. 13 shows changeovers of operative states of the first and second electromagnetic valves 35, 39, the drain shut valve 38, and the second control valve 36 of the system, and changes in the inside-tank pressure PT resulting therefrom, according to the invention. The operative states of the valves are changed over by respective corresponding signals supplied from the ECU 5 (CPU).

Under the normal operating condition (in the normal purging mode), during a time period indicated by (i) in FIG. 13, the first electromagnetic valve 35 is energized, while the second electromagnetic valve 39 is deenergized. When the ignition switch IGSW is closed and the IGSW sensor detects that the engine 1 is in operation, the purge control valve 36 is turned on or opened. Evaporative fuel generated in the fuel tank 23 then flows via the evaporative fuel-guiding passage 27 into the canister 26, where it is temporarily adsorbed by the adsorbent 24. Further, since the second electromagnetic valve 39 is in t...

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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.

Description

BACKGROUND OF THE INVENTION1. Field of the InventionThis invention relates to an evaporative fuel-processing system for internal combustion engines, and more particularly to an evaporative fuel-processing system for internal combustion engines, which is capable of performing abnormality diagnosis of an evaporative emission control system for purging evaporative fuel generated from a fuel tank of the engine into an intake system of same.2. Prior ArtConventionally, there has been widely used an evaporative fuel-processing system for internal combustion engines, which comprises a fuel tank, a canister having an air inlet port provided therein, a first control valve arranged across an evaporative fuel-guiding passage extending from the fuel tank to the canister, and a second control valve arranged across a purging passage extending from the canister to the intake system of the engine.A system of this kind temporarily stores evaporative fuel in the canister, which is then purged into the...

Claims

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Application Information

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IPC IPC(8): F02D41/22F02D41/00F02M25/08
CPCF02D41/003F02D41/1454F02D2041/225F02D2200/0406F02D2200/0414F02D2200/0606F02D2200/703F02M25/0809F02M2025/0845
Inventor KURODA, SHIGETAKASAWAMURA, KAZUTOMOYAMANAKA, MASAYOSHIMARUYAMA, HIROSHICHIKAMATSU, MASATAKANEMOTO, SHOICHISUZUKI, TAKESHI
Owner HONDA MOTOR CO LTD
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