Measuring and testing – With fluid pressure – Motor part or auxiliary
Reexamination Certificate
2002-03-14
2004-03-09
Williams, Hezron (Department: 2856)
Measuring and testing
With fluid pressure
Motor part or auxiliary
C073S04050R, C073S040000, C073S118040
Reexamination Certificate
active
06701777
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a leak determining apparatus, a leak determining method and an engine control unit for an evaporated fuel treatment system, which are adapted to determine the presence or absence of a leak in the evaporated fuel treatment system of an internal combustion engine in which an evaporated fuel generated in a fuel tank is temporarily stored in a canister, and supplies to an intake system as appropriate.
2. Description of the Prior Art
Conventionally, a leak determining apparatus of the type mentioned above is known, for example, from that described in Laid-open Japanese Patent Application No. Hei 6-159157. This evaporated fuel treatment system comprises a canister, a fuel tank, a charge passage, a purge passage, and the like. The canister is connected to a fuel tank through a vapor passage, and connected to an intake pipe of an internal combustion engine through the purge passage. The charge passage is provided with a pressure sensor for detecting a pressure within a space defined by the charge passage and fuel tank (hereinafter called the “inner tank pressure”).
This leak determining apparatus determines the presence or absence of a leak in the evaporated fuel treatment system, and because of possible variations in the fuel level (hereinafter called the “sloshing”), such as a large amount of evaporated fuel generated at the time of determination, additionally determines the presence or absence of sloshing. The sloshing determination for determining the presence or absence of sloshing involves detecting an inner tank pressure at regular time intervals, determining that no sloshing is present when a difference between a current value and the preceding value of the detected inner tank pressure is less than a predetermined value, and determining that sloshing is present when the difference is equal to or larger than the predetermined value. Then, when it is determined that no sloshing is present, the leak determination is executed for determining the presence or absence of a leak. On the other hand, when it is determined that the sloshing is present, the leak determination is suspended for preventing an erroneous determination possibly resulting from the sloshing, and subsequently, the leak determination is kept off until the difference between detected values of the inner tank pressure decreases below the predetermined value.
The conventional leak determining apparatus described above suspends the leak determination for the evaporated fuel treatment system when determining that sloshing is present, and keeps off the leak determination until the difference between detected values of the inner tank pressure decreases below the predetermined value, so that the result of the leak determination may be provided with delay.
The above and other objects, features, and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.
OBJECT AND SUMMARY OF THE INVENTION
The present invention has been made to solve the foregoing problem, and it is an object of the invention to provide a leak determining apparatus, a leak determining method, and an engine control unit for an evaporated fuel treatment system, which are capable of executing a leak determination for an evaporated fuel treatment system without suspending it even in such a condition that variations in fuel level could occur, and capable of accurately providing a leak determination result.
To achieve the above object, according to a first aspect of the present invention, there is provided a leak determining apparatus for an evaporated fuel treatment system for temporarily adsorbing an evaporated fuel generated in a fuel tank in a canister, and supplying the evaporated fuel to an intake system of an internal combustion engine.
The leak determining apparatus according to the first aspect of the present invention is characterized by comprising pressure detecting means for detecting a pressure in the evaporated fuel treatment system; leak determining means for determining the presence or absence of a leak in the evaporated fuel treatment system in accordance with a pressure detected in the evaporated fuel treatment system during a predetermined leak determination period; fuel variation determining means for determining whether or not variations in fuel level occur in the fuel tank in accordance with a change in the pressure of the evaporated fuel treatment system detected during the leak determination period; and correcting means for correcting the value of the detected pressure for use in the leak determination based on the change in pressure detected in the evaporated fuel treatment system when the fuel variation determining means determines that the variations in fuel level occur.
The leak determining apparatus for an evaporated fuel treatment system according to the first aspect of the present invention determines the presence or absence of a leak in the evaporated fuel treatment system in accordance with the pressure in the evaporated fuel treatment system detected during the predetermined leak determination period. The leak determining apparatus also determines whether or not variations in fuel level occur in the fuel tank in accordance with a change in the pressure in the evaporated fuel treatment system detected during the leak determination period, and corrects the value of the detected pressure for use in the leak determination based on the change in the pressure detected in the evaporated fuel treatment system when determining, as a result, that the variations in fuel level occur. In this manner, since the value of the detected pressure for use in the leak determination is corrected based on the change in the pressure caused by the variations in fuel level, the leak determination can be appropriately accomplished even if the variations in fuel level occur, unlike the prior art, by reflecting the change in the pressure caused by the variations in fuel level to maintain the determination accuracy. In this manner, the leak determining apparatus can carry out the leak determination for the evaporated fuel treatment system without suspension even under condition that the variations in fuel level occur, and thereby rapidly and accurately provide a leak determination result.
To achieve the above object, according to a second aspect of the present invention, there is provided a leak determining apparatus for an evaporated fuel treatment system for temporarily adsorbing an evaporated fuel generated in a fuel tank in a canister, and supplying the evaporated fuel to an intake system of an internal combustion engine.
The leak determining apparatus according to the second aspect of the present invention is characterized by comprising a pressure detecting module for detecting a pressure in the evaporated fuel treatment system; a leak determining module for determining the presence or absence of a leak in the evaporated fuel treatment system in accordance with a pressure detected in the evaporated fuel treatment system during a predetermined leak determination period; a fuel level variation determining module for determining whether or not variations in fuel occur in the fuel tank in accordance with a change in the pressure of the evaporated fuel treatment system detected during the leak determination period; and a correcting module for correcting the value of the detected pressure for use in the leak determination based on the change in pressure detected in the evaporated fuel treatment system when the fuel variation determining module determines that the variations in fuel level occur.
This leak determining apparatus provides the same advantageous effects as described above concerning the leak determining apparatus according to the first aspect of the present invention.
To achieve the above object, according to a third aspect of the present invention, there is provided a leak determining method for an evaporated fuel treatment system for temporarily adsorbing an evapor
Isobe Takashi
Yamaguchi Takashi
Honda Giken Kogyo Kabushiki Kaisha
Lahive & Cockfield LLP
Rogers David
Williams Hezron
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