Internal-combustion engines – Charge forming device – Having fuel vapor recovery and storage system
Reexamination Certificate
2000-05-22
2001-09-18
Moulis, Thomas N. (Department: 3747)
Internal-combustion engines
Charge forming device
Having fuel vapor recovery and storage system
Reexamination Certificate
active
06289880
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application is based on Japanese Patent Application No.Hei 11-140942 filed on May 21, 1999 and No.2000-55981 filed on Feb. 28, 2000, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for diagnosing a fuel vapor purge system for an internal combustion engine of a vehicle. The apparatus diagnoses and detects leakage of the system.
2. Description of Related Art
JP-A-05-125997 discloses an apparatus for detecting leakage of a fuel vapor purge system. In this apparatus, a remaining amount of fuel in a tank is taken into consideration of a detection of leakage, because a pressure change in the tank is influenced by a capacity of air in the tank indicated by the remaining amount of fuel in the tank.
However, the pressure in the tank is also changed according to an evaporated amount of fuel after the purge system is hermetically closed.
SUMMARY OF THE INVENTION
The present invention addresses these drawbacks by providing an improved apparatus for detecting leakage of a purge system.
It is therefore an object of this invention to provide an apparatus having improved reliability of a detection of leakage of the purge system.
It is a further object of this invention to provide an apparatus accurately detects leakage of the purge system.
According to a first aspect of the present invention, a requirement for detecting leakage is corrected on the basis of both of an introducing speed of anegative pressure and a capacity of air in a tank. The introducing speed is represented by an introducing time of the negative pressure, a pressure change in a predetermined period of time or a changing rate of pressure. The capacity of air in the tank is represented by a remaining amount of fuel in the tank. The introducing speed indicates an evaporated amount of fuel. Therefore, it is possible to improve a detecting accuracy of leakage.
REFERENCES:
patent: 5317909 (1994-06-01), Yamada et al.
patent: 5425344 (1995-06-01), Osuka et al.
patent: 5699775 (1997-12-01), Azuma
patent: 6082337 (2000-07-01), Fujimoto et al.
patent: 7-12014 (1995-01-01), None
Mukai Yasuo
Nakayama Masaaki
Yamaguchi Masahiko
Denso Corporation
Moulis Thomas N.
Nixon & Vanderhye P.C.
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