| 摘要 |
<p>PURPOSE:To positively detect any failure of switching mechanisms by a means of a relatively simple configuration by detecting fluid pressure between a control valve and a valve timing switching mechanisms, and fluid pressure on the downstream side of the switching mechanisms by means of two fluid pressure sensors. CONSTITUTION:An oil pressure sensor 18 for detecting the oil pressure of oil feeding passages 88i, 88e is mounted to a housing of a selector valve 99. On the oil feeding passages 88i, 88e, oil pressure sensors 19, 20 are mounted respectively on the downstream side of connecting-switching mechanisms 56i, 56e or on the upstream side of throttles 106i, 106e. A solenoid valve 23 outputs a command signal, and when the selector valve 99 is closed or (when selection of low speed or high speed valve timing is commanded), all detection values of the oil pressure sensors 18 - 20 become nearly equal to a specified pressure P1 or a specified pressure P2. Thus, failures in the switching valve 99, the connecting-switching mechanisms 56i, 56e, etc. can be detected by comparing the detection values of the oil pressure sensors 18 - 20 with the specified pressures P1, P2 in response to a switching command signal of the solenoid valve 23.</p> |
