Leak detector for fuel vapor purge system

• US 20060090553A1
• Filed: 11/02/2005
• Published: 05/04/2006
• Est. Priority Date: 11/02/2004
• Status: Active Grant

• Current Assignee: DENSO Corporation, Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: DENSO Corporation, Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Nagasaki, Kenji, Miyahara, Hideki, Ito, Tokiji
• Granted Patent: US 7,284,530 B2
• Time in Patent Office: Days
• US Class Current: 73/114.43
• CPC Class Codes: F02M 25/0818 having means for pressurising the evaporative emission space
• 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
• CPC Class Codes: F02M 25/0854 Details of the absorption canister
• CPC Class Codes: F02M 25/0872 Details of the fuel vapour pipes or conduits
• CPC Class Codes: F02M 25/089 Layout of the fuel vapour installation

Abstract

A suction pump introduces negative pressure into a reference-pressure-detecting portion. A driving voltage V of the suction pump is adjusted in such a manner that pressure Pr in the reference-pressure-detecting portion is within a target pressure range. When the pressure Pr is brought into the target pressure range, the driving voltage V of the suction pump is stored as a first driving voltage V1 and the pressure Pr is stored as a reference pressure Pr. When pressure detection and leak detection process are conducted, the suction pump is driven at the first driving voltage V1 to introduce the negative pressure. The computer compares the pressure Pr with a leak determination value to determine whether a leak exists.

Claims

1. A leak detector for a fuel vapor purge system introducing a fuel vapor in a fuel tank into an intake pipe of an internal combustion engine, the leak detector comprising:

a pressure-introducing-detecting apparatus including

a pressure introducing unit introducing a pressure into the fuel vapor purge system including the fuel tank;

a reference-pressure-detecting portion provided with a reference aperture having a predetermined inner diameter; and

a switching unit switching between a passage for introducing the pressure into the reference-pressure-detecting portion and a passage for introducing the pressure into the fuel vapor purge system; and

a leak determination unit detecting a reference pressure information representing a reference pressure adjusted by the reference aperture or a correlating information of the reference pressure, the leak determination unit detecting a system pressure information representing a system pressure in the fuel vapor purge system or a correlating information of the system pressure, the leak determination unit determining whether a leak exists by comparing the reference pressure information with the system pressure information, wherein

the leak determination unit adjusts a control value of the pressure introducing unit in such a manner that the reference pressure information becomes the target condition to set the control value as a first control value, and drives the pressure introducing unit at the first control value during a detecting operation of the system pressure information.

2. The leak detector according to claim 1, wherein

the leak determination unit sets a second control value by correcting the first control value in a case that a leak hole corresponding to a second aperture of which diameter is different from a diameter of the reference aperture is detected, and drives the pressure introducing unit at the second control value.

3. The leak detector according to claim 1, wherein

the pressure introducing unit is a suction pump which introduces negative pressure into the fuel vapor purge system.

4. The leak detector according to claim 1, wherein

the pressure introducing unit is a discharge pump which introduces positive pressure into the fuel vapor purge system.

5. The leak detector according to claim 1, wherein

the leak determination unit determines whether the control value is within a predetermined range when the control value of the pressure introducing unit is adjusted in order to determine whether a pressure-introducing-detecting apparatus has a defect.

6. The leak detector according to claim 1, wherein

a kinetic characteristic of the pressure introducing unit is utilized as the reference pressure information and the system pressure information.