Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Reexamination Certificate
2003-10-29
2004-08-17
Denion, Thomas (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
C123S090170, C123S090160, C123S090310
Reexamination Certificate
active
06776130
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a control apparatus and a control method of a variable valve timing mechanism that varies valve timing of engine valves by changing a rotation phase of a camshaft relative to a crankshaft.
RELATED ART OF THE INVENTION
Heretofore, there has been known a control apparatus of a variable valve timing mechanism as disclosed in Japanese Unexamined Patent Publication No. 2000-297686.
Such a conventional control apparatus comprises a cam sensor outputting a signal at a reference rotation position of a camshaft, and a crank angle sensor outputting a signal at a reference rotation position of a crankshaft.
In such a control apparatus, an angle of from the reference rotation position of the crankshaft to the reference rotation position of the camshaft is detected based on signals from the cam sensor and the crank angle sensor.
Then, an actuator of the variable valve timing mechanism is feedback controlled so that the above angle (rotation phase) reaches a desired value.
According to the above constitution, the rotation phase is detected at each fixed crank angle.
However, a feedback control of actuator is typically executed at each fixed period of time (for example, 10 ms).
Therefore, at a low rotation time of engine, a detection period of rotation phase becomes longer than a period of feedback control.
At this time, the feedback control is executed based on the rotation phase which differs from an actual rotation phase, during a detection value of the rotation phase is updated. As a result, there occurs the overshooting of rotation phase.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to enable to prevent the overshooting of rotation phase when a detection period of rotation phase becomes longer than a period of feedback control.
In order to accomplish the above-mentioned object, the present invention is constituted so that a rotation phase is detected based on a signal synchronized with the rotation of a crankshaft and a signal synchronized with the rotation of a camshaft, and also controlled variable of an actuator of a variable valve timing mechanism is detected, to convert the controlled variable into the rotation phase with a transfer function representing the variable valve timing mechanism.
Then, an estimation value of the rotation phase is calculated based on the rotation phase detected based on the rotation synchronized signals and the rotation phase obtained by converting the controlled variable, and an operation signal is output to the actuator based on the estimation value and a desired value.
The other objects and features of the invention will become understood from the following description with reference to the accompanying drawings.
REFERENCES:
patent: 4282573 (1981-08-01), Imai et al.
patent: 5363817 (1994-11-01), Ikeda et al.
patent: 6502543 (2003-01-01), Arai et al.
patent: 6684837 (2004-02-01), Miyakoshi
patent: 6691024 (2004-02-01), Kunz
patent: 2000-297686 (2000-10-01), None
Machida Kenichi
Miyakoshi Ryo
Chang Ching
Denion Thomas
Foley & Lardner LLP
Hitachi Unisia Automotive Ltd.
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