| 摘要 |
PURPOSE:To prevent a direction change-over valve from vibrating, by directly change and control a signal oil pressure of the direction changeover valve for changing over an oil pressure to oil pressure actuators for moving rocker arms by a change-over operation valve, and changing over the direction change-over valve immediately before the release of a stopper for locking the direction change-over valve. CONSTITUTION:When part of cylinders is at rest, a change-over apparatus actuates the oil pressure actuators 13, 13', 14, 14' to move the rocker arms 11, 11', 12, 12' toward the axes of the focker shafts, and change-over from the engagement with operation cams 17a, 17a', 17b, 17b' to the engagement with resting cams 17c, 17c' 17d, 17d' is effected thereby making suction and exhaust valves 9, 9', 10, 10' inactive. The oil pressure actuators 13, 13', 14, 14' are connected with oil pressure supply paths and oil return paths via a direction change-over valve 7. The change-over operation valve 31 is provided that is capable of changing, in accordance with the conditions of operation of the engine, the oil pressure that will be applied to an oil chamber of the valve 7 and to an oil chamber of an oil pressure clutch 23 interposed in a transmission system between a timing drifter 8 and a stopper 20. |
