| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an electrohydrostatic control valve that is applied to a valve timing changing device and can reduce power consumption, can suppress heat generation, and can secure smooth operation by hydraulic fluid supply at disconnection. <P>SOLUTION: The electrohydrostatic control valve includes a valve element 110 for opening and closing a passage communicatively connected to an advance chamber and a retard chamber to supply or discharge hydraulic fluids to/from the chambers, a spring 130 for biasing the valve element in one direction, and an electromagnetic actuator 140 for driving the valve element while being duty-controlled so that a duty value is increased in a direction against a biasing force of the spring; and performs switching according to an engine operation state into an advance mode, a retard mode, a hold mode for holding the valve element in a predetermined intermediate phase, and a drain mode for discharging the hydraulic fluid in the advance chamber and the retard chamber where the electromagnetic actuator drives the valve element into the drain mode at a side where the duty value becomes maximum. Thereby, power consumption can be reduced, heat generation can be suppressed, and smooth operation by the supply of the hydraulic fluid can be secured when disconnected. <P>COPYRIGHT: (C)2013,JPO&INPIT |
