Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Reexamination Certificate
2000-10-04
2001-12-25
Walberg, Teresa (Department: 3742)
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
C123S090170, C123S090120, C123S090310
Reexamination Certificate
active
06332438
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vane-type valve timing control apparatus and control method for an internal combustion engine. More specifically, the invention relates to a vane-type valve timing control apparatus having a resilient member for urging the vanes secured to the cam shaft toward the advance angle side or the delay angle side, and control method.
2. Related Art of the Invention
As a vane type variable valve timing control apparatus, there is one heretofore disclosed in Japanese Unexamined Patent Publication Nos. 10-141022 and 10-068306.
With this apparatus, recess portions are formed on an inner peripheral face of a cylindrical housing secured to a cam sprocket, while vanes secured to a cam shaft are accommodated in the recess portions, the construction being such that the cam shaft can rotate relatively with respect to the cam sprocket, within a range in which the vanes can move inside the recess portions.
Furthermore, the construction is such that by supplying and discharging oil by means of a spool valve, relatively with respect to a pair of hydraulic chambers (advance angle side hydraulic chamber and delay angle side hydraulic chamber) formed by the vanes partitioning the recess portions into front and rear in the rotation direction, the position of the vanes in the recess portions is changed, thereby enabling a rotation phase of the cam shaft relative to a crank shaft to be continuously changed.
A control value of the spool valve is determined by adding a feedback correction value set depending on a deviation of an actual rotation phase from a target value, to a constant neutral control value (basic control value) for retaining a rotation phase. A dither signal is then superimposed on the determined control value which is then output to an actuator of the spool valve.
However, as disclosed in Japanese Unexamined Patent Publication No. 10-068306, in the case where a resilient body such as a spiral spring for urging the vane to the advance angle side or to the delay angle side is provided, the urging force of the resilient body varies due to the rotation phase. Therefore, the response characteristic in the feedback correction of the rotation phase varies depending on the rotation phase and the direction of change thereof, causing a delay in the response to a particular change in the rotation phase.
SUMMARY OF THE INVENTION
In view of the above problems, it is an object of the present invention, with a vane type variable valve timing control apparatus comprising a resilient body for urging a vane to an advance angle side or to a delay angle side with respect to a cam sprocket, to enable a feedback control to be executed with an equivalent response characteristic for each rotation phase and to enable a target rotation phase to be precisely maintained without a response delay.
In order to accomplish the above-mentioned object, according to the present invention, a gain in a feedback control for bringing the rotation phase into agreement with a target is changed over according to a target rotation phase.
According to this constitution, the gain in the feedback control is changed over according to the urging force of the resilient member that differs depending on the rotation phase, thereby preventing the occurrence of a delay in the response at a particular rotation phase, to accomplish a target rotation phase by the feedback control while maintaining a high response characteristic at all times.
Further, the constitution may be such that the gain in the feedback control for bringing the rotation phase into agreement with the target, is changed over according to a direction in which the rotation phase is changed.
According to this constitution, the gain in the feedback control is changed over according to a change in the urging force of the resilient member caused by the direction in which the rotation phase is changed, thereby preventing the occurrence of a delay in the response due to the direction in which the rotation phase is changed, to accomplish a target rotation phase by the feedback control while maintaining a high response characteristics at all times.
Further, the constitution may be such that the gain in the feedback control for bringing the rotation phase into agreement with the target, is changed over according to the target rotation phase and the direction in which the rotation phase is changed.
According to this constitution, the gain in the feedback control is changed over according to the urging force of the resilient member that differs depending on a change in the rotation phase and according to a change in the urging force of the resilient member that differs depending on the direction in which the rotation phase is changed, thereby preventing the occurrence of a delay in the response at a particular rotation phase or a delay in the response due to the direction in which the rotation phase is changed, to accomplish a target rotation phase by the feedback control while maintaining a high response characteristic at all times.
The other objects and features of the present invention will become obvious from the following description of the related embodiment in connection with the accompanying drawings.
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Dahbour Fadi H.
McDermott & Will & Emery
Unisia Jecs Corporation
Walberg Teresa
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