Fault diagnostic apparatus of evaporation purge system

• US 6,631,635 B2
• Filed: 12/03/2001
• Issued: 10/14/2003
• Est. Priority Date: 06/15/2001
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Hanazaki, Ryoichi, Nakamichi, Masaki
• Primary Examiner(s): Cuneo, Kamand
• Assistant Examiner(s): Harrison, Monica D.
• Application Number:
  US09/997,991
• Publication Number:
  US 20020189596A1
• Time in Patent Office: 680 Days
• Field of Search: 731/16, 731/172, 731/181, 123/198.D, 123/516, 123/518, 123/519, 123/520, 123/521
• US Class Current: 73/114.39
• CPC Class Codes: F02M 25/0809 Judging failure of purge control system

Abstract

To obtain a fault diagnostic apparatus of an evaporation purge system by which a fault detection of a purge vent valve can accurately be performed with no wrong judgment. There are included: a tank internal pressure detecting means for detecting an internal pressure of a fuel tank; a valve control means for controlling closing and opening of a purge control valve and the purge vent valve; a purge control valve fault detecting means for detecting a fault of the purge control valve on the basis of a detected output of the tank internal pressure detecting means when the purge control valve and the purge vent valve are closed; and a purge vent valve fault detecting means for detecting a fault of the purge vent valve on the basis of the detected output of the tank internal pressure detecting means when the purge control valve and the purge vent valve are open, and the purge vent valve fault detecting means performs the fault detection of the purge vent valve only when the purge control valve fault detecting means judges that the purge control valve is normal.

Claims

1. In an evaporation purge system including:

a fuel tank;

a canister having an intake hole;

a purge control valve provided in a purge passage connecting said canister and an intake system of an internal combustion engine; and

a purge vent valve for opening and closing the intake hole of said canister,

a fault diagnostic apparatus of an evaporation purge system, comprising;

tank internal pressure detecting means for detecting internal pressure of said fuel tank;

valve control means for controlling closing and opening of said purge control valve and said purge vent valve;

purge control valve fault detecting means for detecting a fault of said purge control valve on the basis of detected output of said tank internal pressure detecting means, at the time of the closed state of said purge control valve and said purge vent valve; and

purge vent valve fault detecting means for detecting a fault of said purge vent valve on the basis of detected output of said tank internal pressure detecting means, at the time of the opening state of said purge control valve and said purge vent valve,

wherein said purge vent valve fault detecting means performs fault detection of said purge vent valve, only when said purge control valve fault detecting means judges that said purge control valve is normal.

2. The fault diagnostic apparatus of an evaporation purge system according to claim 1,

wherein said purge control valve fault detecting means judges that said purge control valve is in trouble, when the tank internal pressure detected by said tank internal pressure detecting means becomes lower than a specified value, in the case where said purge control valve and said purge vent valve are set to the closed state by said valve control means.

3. The fault diagnostic apparatus of an evaporation purge system according to claim 1,

wherein said purge vent valve fault detecting means judges that said purge vent valve is in trouble, when the tank internal pressure detected by said tank internal pressure detecting means becomes lower than a specified value, in the case where said purge control valve and said purge vent valve are set to the opening state by said valve control means.

4. An evaporation purge system comprising:

a fuel tank;

a canister having an intake hole;

a purge control valve provided in a purge passage connecting said canister and an intake system of an internal combustion engine;

a purge vent valve for opening and closing the intake hole of said canister; and

a fault diagnostic apparatus including

a) tank internal pressure detecting means for detecting internal pressure of said fuel tank;

b) valve control means for controlling closing and opening of said purge control valve and said purge vent valve;

c) purge control valve fault detecting means for detecting a fault of said purge control valve on the basis of detected output of said tank internal pressure detecting means, at the time of the closed state of said purge control valve and said purge vent valve; and

d) purge vent valve fault detecting means for detecting a fault of said purge vent valve on the basis of detected output of said tank internal pressure detecting means, at the time of the opening state of said purge control valve and said purge vent valve,

wherein said purge vent value fault detecting means performs fault detection of said purge vent valve, only when said purge control valve fault detecting means judges that said purge control valve is without a fault.

5. The evaporation purge system according to claim 4,

wherein said purge control valve fault detecting means judges that said purge control valve has a fault when the tank internal pressure detected by said tank internal pressure detecting means becomes lower than a specified value.

6. The evaporation purge system according to claim 4,

wherein said purge vent value fault detecting means judges that said purge vent valve has a fault when the tank internal pressure detected by said tank internal pressure detecting means becomes lower than a specified value.