| 摘要 |
<p>PROBLEM TO BE SOLVED: To diagnose with high accuracy the failure of a variable valve timing mechanism varying the rotational phase of a camshaft by hydraulic pressure while securing plenty diagnostic chances. SOLUTION: While reference delay time is set based on an engie speed Ne correlated with the delivery of a hydraulic pump and a cooling water temperature Tw correlated with viscosity of hydraulic fluid (S1, S2), a correction coefficient k is set according to the changing widthΔT of a target rotational phase (valve timing), and this reference delay time is corrected by the correction coefficient k (S4), to set the final delay time (S5). After this final delay time is passed from a point of time when the target rotational phase is stepwise changed, the actual rotatoinal phase and the target rotational phase are compared with each other, and the failure of this variable valve timing mechanism is diagnosed (S8→S9).</p> |
