Invention Grant
US08457864B2 Variable valve timing control apparatus for internal combustion engine 有权
内燃机可变气门正时控制装置

Variable valve timing control apparatus for internal combustion engine
Abstract:
A variable valve timing control apparatus for an engine includes a hydraulic variable valve timing unit and an oil pressure control device. The variable valve timing unit has a plurality of control ranges and an ambiguity range. The apparatus learns a hold control amount for each of the plurality of control ranges when a predetermined condition is satisfied, and the hold control amount is required to control the oil pressure control device to maintain the actual VCT phase. When the target VCT phase is positioned in the ambiguity range, if a difference between the actual and target VCT phases is stably greater than a predetermined value, the apparatus switches the presently-used hold control amount learning value of one control range into the learning value for the other control range in order to compute the VCT control amount.
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