Leak diagnostic apparatus for a vaporized fuel processing system

• US 20070068227A1
• Filed: 09/27/2006
• Published: 03/29/2007
• Est. Priority Date: 09/28/2005
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd., Nissan Technical Center North America Incorporated (Nissan Motor Co., Ltd.)
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Watanabe, Kazuhisa, Ishii, Hiroya, Tsuyuki, Takeshi
• Granted Patent: US 7,685,867 B2
• Time in Patent Office: Days
• US Class Current: 73/49.700
• CPC Class Codes: F02M 25/0809 Judging failure of purge control system

Abstract

A leak diagnostic apparatus for a vaporized fuel processing system that purges vaporized fuel in a fuel tank of a vehicle is disclosed. The leak diagnostic apparatus comprises a leak diagnostic device, a fuel tank condition detection device and a determining device. The leak diagnostic device carries out a leak diagnosis of the vaporized fuel processing system while the engine is operating. The fuel tank condition detection device detects the conditions in the fuel tank. The determining device determines whether the leak diagnosis should be carried out based on predetermined conditions in the fuel tank.

Claims

1. A leak diagnostic apparatus for a vaporized fuel processing system that purges vaporized fuel in a fuel tank of a vehicle, comprising:

a leak diagnostic device that carries out a leak diagnosis of the vaporized fuel processing system while the engine is operating;

a fuel tank condition detection device that detects the conditions in the fuel tank; and

a determining device that determines if the leak diagnosis should be carried out based on predetermined conditions in the fuel tank.

2. A leak diagnostic apparatus for a vaporized fuel processing system according to claim 1, wherein:

the fuel tank condition detection device detects the fuel volume in the fuel tank; and

the determining device makes a determination as to whether the leak diagnosis should be carried out based on the detected fuel volume of the fuel tank.

3. A leak diagnostics apparatus for a vaporized fuel processing system according to claim 2,

wherein the determining device makes the determination that permits execution of the leak diagnosis when the fuel volume is the same as or greater than a designated fuel volume.

4. A leak diagnostic apparatus for a vaporized fuel processing system according to claim 1, further comprising:

a first leak diagnostic device and a second leak diagnostic device;

wherein the first leak diagnostic device carries out a first leak diagnosis of the vaporized fuel processing system while the engine is operating; and

the second leak diagnostic device carries out a second leak diagnosis of the vaporized fuel processing system after the engine has stopped.

5. A leak diagnostic apparatus for a vaporized fuel processing system according to claim 4, wherein the fuel tank condition detection device determines whether the first leak diagnosis or the second leak diagnosis should be carried out.

6. A leak diagnostic apparatus for a vaporized fuel processing system according to claim 5, wherein:

the fuel tank condition detection device detects fuel volume in the fuel tank; and

the determining device makes a determination that permits execution of the first leak diagnosis when the fuel volume is the same as or greater than the designated fuel volume, and makes a determination that permits execution of the second leak diagnosis when the fuel volume is less than the designated fuel volume.

7. A leak diagnostics apparatus for a vaporized fuel processing system according to claim 1, wherein:

the fuel tank condition detection device detects fuel temperature in the fuel tank; and

the determining device makes a determination as to whether the leak diagnosis should be carried out based on the detected fuel temperature.

8. A leak diagnostics apparatus for a vaporized fuel processing system according to claim 7 wherein:

the determining device makes the determination to permit the leak diagnosis when the fuel temperature is less than a designated temperature.

9. A leak diagnostics apparatus for a vaporized fuel processing system according to claim 7 further comprising:

a first leak diagnostic device and a second leak diagnostic device;

wherein the first leak diagnostic device carries out a first leak diagnosis of the vaporized fuel processing system while the engine is operating; and

wherein the second leak diagnostic device that carries out a second leak diagnosis of the vaporized fuel processing system after the engine has stopped; and

wherein the determining device makes a determination to permit execution of the first leak diagnosis when the fuel temperature is less than a designated temperature, and makes a determination to permit execution of the second leak diagnosis when the fuel temperature is the same or greater than the designated temperature.

10. A leak diagnostics apparatus for a vaporized fuel processing system according to claim 9, further comprising:

an ambient temperature detection device that detects ambient temperature, and

wherein if the determination is made for the second leak diagnosis to be carried out, the determining device further makes an additional determination as whether or not the second leak diagnosis should be carried out by comparing the difference between the fuel temperature and the ambient temperature.

11. A leak diagnostics apparatus for a vaporized fuel processing system according to claim 10 wherein:

the determination device makes the determination to carry out the second leak diagnosis when the difference between the fuel temperature and the ambient temperature is the same or greater than a designated temperature difference, and to invalidate the second leak diagnosis when the difference between the fuel temperature and ambient temperature is less than the designated temperature difference.

12. A leak diagnostics apparatus for a vaporized fuel processing system according to claim 1, wherein:

the fuel tank condition detection device detects gas space in the fuel tank; and

the determining device makes the determination to permit execution of the leak diagnosis when the detected gas space is less than a designated gas space.

13. A leak diagnostics apparatus for a vaporized fuel processing system according to claim 12, further comprising:

a first leak diagnostic device that carries out a first leak diagnosis of the vaporized fuel processing system while the engine is operating;

a second leak diagnostic device that carries out a second leak diagnosis of the vaporized fuel processing system after the engine has stopped; and

wherein the determining device makes the determination to permit the first leak diagnosis when the detected gas space is less than a designated gas space, and makes the determination to permit the second leak diagnosis when the gas space is the same or greater than the designated gas space.

14. A leak diagnostics apparatus for a vaporized fuel processing system according to claim 1, wherein

the vaporized fuel processing system further comprises a valve that may selectively block a passage in the vaporized fuel processing system;

and

a pressure detection device that detects pressure in the vaporized fuel processing system wherein;

the leak diagnosis device uses negative pressure in an inlet passage that is generated while the engine is in operation to reduce the pressure inside the vaporized fuel processing system, and then the leak diagnosis device closes the valve to create a closed space in the vaporized fuel processing system with a reduced pressure and a leak diagnosis is carried out based on a pressure value inside the system that is detected by the pressure detection device.

15. A leak diagnostics apparatus for a vaporized fuel processing system according to claim 4 wherein:

the vaporized fuel processing system is further comprised of a valve that may selectively block a passage in the vaporized fuel processing system; and

a pressure detection device that detects the pressure in the vaporized fuel processing system wherein;

the second leak diagnosis device creates a closed space in the vaporized fuel processing system by closing the valve after the engine is stopped, and carries out the second leak diagnosis based on a pressure value in the system detected by the pressure detection device.

16. A method for performing leak diagnosis in a vaporized fuel processing system, comprising:

detecting the operation status of an engine;

detecting a condition of the interior of a fuel tank; and

determining a leak diagnosis based on the detected condition of the interior of the fuel tank while the engine is operating.

17. A method for performing leak diagnosis in a vaporized fuel processing system according to claim 16, further comprising:

determining a first leak diagnosis based on the detected condition of the interior of the fuel tank while the engine is operating; and

determining a second leak diagnosis based on the detected condition of the interior of the fuel tank while the engine has stopped.

18. A leak diagnostics system for a vaporized fuel processing system that purges the vaporized fuel in the vehicle fuel tank comprising:

means for detecting the operation status of an engine;

means for detecting a conditions of the interior of the fuel tank; and

means for determining a leak diagnosis based on a detected condition of the interior of the fuel tank while the engine is operating.