Leak check for fuel vapor purge system

• US 6,892,712 B2
• Filed: 08/30/2002
• Issued: 05/17/2005
• Est. Priority Date: 09/11/2001
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Miwa, Makoto, Maegawa, Yoshinori, Wakahara, Keiji, Morinaga, Syujiro
• Primary Examiner(s): MILLER, CARL STUART
• Application Number:
  US10/231,065
• Publication Number:
  US 20030056573A1
• Time in Patent Office: 991 Days
• Field of Search: 123/520, 123/521, 123/518, 123/519, 123/516, 123/198.D, 731/181, 731/16
• US Class Current: 123/520
• CPC Class Codes: F02M 2025/0845 Electromagnetic valves
• CPC Class Codes: F02M 25/0809 Judging failure of purge control system
• CPC Class Codes: F02M 25/0836 Arrangement of valves controlling the admission of fuel vapour to an engine, e.g. valve being disposed between fuel tank or absorption canister and intake manifold

Abstract

A leak check system executes a leak check processing. In the leak check processing, the system closes a canister valve and a purge valve to close the fuel vapor purge system. Then, the system detects and monitors a pressure in the fuel vapor purge system. During the leak check processing, the system detects a rapid change of the pressure that is caused by a deformation of a wall of a fuel tank. The system cancels or suspends the processing to avoid erroneous detection of the leak. If the leak check is canceled, the system opens the canister valve to open the fuel vapor purge system.

Claims

1. An apparatus of checking a leak in a fuel vapor purge system comprising:

pressure detecting means for detecting a pressure of a fuel vapor purge system including a fuel tank;

leak checking means for checking presence or absence of the leak in the fuel vapor purge system based on the pressure of the fuel vapor purge system detected by the pressure checking means when the fuel vapor purge system is maintained in a hermetically closed state;

erroneous check avoiding means for avoiding an erroneous check caused by a deformation of the fuel tank;

restricting means for restricting the pressure of the fuel vapor purge system into a predetermined restricted value when the leak checking means checks the leak;

temperature determining means for determining a temperature in the fuel tank or a temperature around the fuel tank or information related thereto; and

means for changing the restricted value based on the temperature determined by the temperature determining means.

2. The apparatus of checking a leak of a fuel vapor purge system according to claim 1, wherein the restricting means restricts increase of the pressure.

3. An apparatus of checking a leak in a fuel vapor purge system comprising:

pressure detecting means for detecting a pressure of a fuel vapor purge system including a fuel tank;

leak checking means for checking presence or absence of the leak in the fuel vapor purge system based on the pressure of the fuel vapor purge system detected by the pressure checking means when the fuel vapor purge system is maintained in a hermetically closed state;

erroneous check avoiding means for avoiding an erroneous check caused by a deformation of the fuel tank;

restricting means for restricting the pressure of the fuel vapor purge system into a predetermined restricted value when the leak checking means checks the leak; and

means for correcting the restricted value in a direction of approaching an atmospheric pressure when the pressure of the fuel vapor purge system detected by the pressure detecting means is rapidly changed in checking the leak by the leak checking means.

4. The apparatus of checking a leak of a fuel vapor purge system according to claim 3, wherein the restricting means restricts increase of the pressure.

5. An apparatus of checking a leak of a fuel vapor purge system which is a fuel vapor purge system for purging fuel vapor generated by evaporating a fuel in a fuel tank to an intake system of an engine, said apparatus comprising:

pressure detecting means for detecting a pressure of the fuel vapor purge system including the fuel tank;

a first valve for opening and closing an atmosphere communicating path of the fuel vapor purge system;

leak checking means for checking presence or absence of a leak of the fuel vapor purge system based on the pressure detected by the pressure detecting means when at least the first valve is closed to thereby maintain the fuel vapor purge system in a hermetically closed state in stopping to operate the engine; and

valve controlling means for temporarily releasing the hermetically closed state of the fuel vapor purge system by temporarily opening the first valve after finishing to check the leak and thereafter closing the first valve again.

6. The apparatus of checking a leak of a fuel vapor purge system according to claim 5, wherein the valve controlling means closes the first valve at a time point at which the pressure detected by the pressure detecting means becomes lower than a predetermined determinant when the first valve is opened after finishing to check the leak.

7. The apparatus of checking a leak of a fuel vapor purge system according to claim 5, wherein the valve controlling means does not open the first valve when the pressure detected by the pressure detecting means becomes equal to or smaller than a predetermined determinant in finishing to check the leak.

8. A method of checking a leak in a fuel vapor purge system, the method comprising:

detecting a pressure of a fuel vapor purge system including a fuel tank;

checking presence or absence of a leak in the fuel vapor purge system based on the detected pressure of the fuel vapor purge system when the fuel vapor purge system is maintained in a hermetically closed state;

avoiding an erroneous check caused by a deformation of the fuel tank;

restricting the pressure of the fuel vapor purge system into a predetermined restricted value when the leak is checked;

determining a temperature in the fuel tank or a temperature around the fuel tank; and

changing the restricted value based on the determined temperature.

9. The method of checking a leak of a fuel vapor purge system according to claim 8, wherein restricting the pressure of the fuel vapor purge system includes restricting an increase of the pressure.

10. A method of checking a leak in a fuel vapor purge system, the method comprising:

detecting a pressure of a fuel vapor purge system including a fuel tank;

checking presence or absence of a leak in the fuel vapor purge system based on the detected pressure of the fuel vapor purge system when the fuel vapor purge system is maintained in a hermetically closed state;

avoiding an erroneous check caused by a deformation of the fuel tank;

restricting the pressure of the fuel vapor purge system into a predetermined restricted value when the leak is checked; and

corrected the restricted value in a direction of approaching an atmospheric pressure when the detected pressure is rapidly changed in the checking of the leak.

11. The method of checking a leak of a fuel vapor purge system according to claim 10, wherein restricting the pressure of the fuel vapor purge system includes restricting an increase of the pressure.

12. A method of checking a leak of a fuel vapor purge system which is a fuel vapor purge system for purging fuel vapor generated by evaporating a fuel in a fuel tank to an intake system of an engine, said method comprising:

detecting a pressure of the fuel vapor purge system including the fuel tank;

opening and closing an atmosphere communicating path of the fuel vapor purge system via a first valve;

checking presence or absence of a leak of the fuel vapor purge system based on the detected pressure when at least the first valve is closed to thereby maintain the fuel vapor purge system in a hermetically closed state in stopping to operate the engine; and

temporarily releasing the hermetically closed state of the fuel vapor purge system by temporarily opening the first valve after finishing to check the leak and thereafter closing the first valve again.

13. The method of checking a leak of a fuel vapor purge system according to claim 12, wherein the first valve is closed at a time point at which the detected pressure becomes lower than a predetermined determinant when the first valve is opened after finishing to check the leak.

14. The method of checking a leak of a fuel vapor purge system according to claim 12, wherein the first valve is not opened when the detected pressure becomes equal to or smaller than a predetermined determinant in finishing to check the leak.