CONTROLLING VARIABLE VALVE-ACTION-MODE TYPE TAPPET FOR INTERNAL COMBUSTION ENGINE

摘要

PURPOSE:To shorten the time required for a solenoid valve to complete its change-over action by controlling the opening action of the solenoid valve when the change-over of an oil hydraulic circuit is completed, in the case where either of the two cams having varied valve timing is selected arbitrarily by changing over the oil hydraulic circuit to the solenoid valve in accordance with the operating state of an engine. CONSTITUTION:A rocker arm 18 for operating two intake valves is operated selectively either by two of the No.1 cam 42 or by two of the No.2 cam 44. On the edge of a sliding shaft 46 in a rocker arm shaft 20 is provided an oil hydraulic pump 84, and by the action of a solenoid valve 88 for controlling the discharge of pressure oil in the pump room 84, the sliding shaft 46 is caused to slide by virtue of hydraulic pressure. In a control device 100, according to the operating state of an engine, the solenoid valve 88 is caused to perform a closing-opening-closing action so that the cams are changed over, while, at the valve opening time after the completion of a mode change-over, the valve opening action is started immediately after the cam for the pump passes through its maximum lift position.