Measuring and testing – Simulating operating condition – Marine
Reexamination Certificate
1999-04-06
2001-12-04
Fuller, Benjamin R. (Department: 2855)
Measuring and testing
Simulating operating condition
Marine
Reexamination Certificate
active
06324903
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to an apparatus and method for detecting atmospheric pressure in an internal combustion engine, and more particularly to a technique for detecting atmospheric pressure by using an aspiration pressure sensor during operation of the internal combustion engine.
2. Description of the Related Art
In general, the aspiration pressure sensor detects aspiration pressure at the lower reaches of a throttle valve in the internal combustion engine. When an open angle of the throttle valve is at full opening position, the aspiration pressure detected by the aspiration pressure sensor is roughly equal to the atmospheric pressure.
A Japanese Patent Publication No. Heisei 7-35749, published on Apr. 19, 1995, exemplifies a previously proposed apparatus for detecting atmospheric pressure in an internal combustion engine.
In the disclosure of the above-mentioned Japanese Patent Publication, when the open angle of the throttle valve is at a full opening position, atmospheric pressure is detected by the aspiration pressure sensor. If atmospheric pressure is only detected when the open angle of the throttle valve is at the full opening position, it is difficult to have a sufficient opportunity to accurately detect the atmospheric pressure. Therefore, when the open angle of the throttle valve is above a threshold level, the pressure detected by the aspiration pressure sensor is assumed to be the atmospheric pressure.
However, in a case of detecting atmospheric pressure when the open angle of the throttle valve is above the threshold level, the most recent detected value of the aspiration pressure sensor is assumed to be the atmospheric pressure, which value always updates a previously-stored value. As a result, when the open angle of the throttle valve decreases below the threshold level after full opening of the throttle valve, the storage value is updated by a low precision value which is detected by the lower open angle of the throttle valve, and this value replaces the previously-stored value corresponding to a full opening of the throttle valve.
Though the detecting precision can be maintained by selecting the threshold level closer to the full opening of the throttle valve, it is still difficult to have a sufficient opportunity to accurately detect the atmospheric pressure.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide an apparatus and method for detecting atmospheric pressure in an internal combustion engine which can detect atmospheric pressure accurately while providing a sufficient opportunity to detect the atmospheric pressure.
To satisfy the foregoing and other objects, an apparatus and corresponding method for detecting atmospheric pressure in an internal combustion engine is provided, comprising: open angle detecting means for detecting an open angle of a throttle valve; and atmospheric pressure detecting means for updating atmospheric pressure based on aspiration pressure when the open angle of the throttle valve is above a threshold value and is increasing. The apparatus further comprises open angle clearing means for closing the open angle of the throttle valve when the present open angle of the throttle valve is under the threshold value or for closing the last updated open angle of the throttle valve after a predetermined time. In a further aspect of the present invention, the apparatus further comprises timer means for determining whether an elapsed-time exceeds the predetermined time or not.
REFERENCES:
patent: 4938195 (1990-07-01), Miyazaki et al.
patent: 5456231 (1995-10-01), Suzuki et al.
patent: 5614667 (1997-03-01), Hosoya
Kanai Shinji
Ohsaki Masanobu
Foley & Lardner
Fuller Benjamin R.
Stevens Maurice
Unisia Jecs Corporation
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