Hydraulic actuator for an internal combustion engine

摘要

A camless intake/exhaust valve for an internal combustion engine that is controlled by a solenoid actuated fluid control valve. The control valve has a pair of solenoids that move a spool. Energizing one solenoid moves the spool and valve into an open position. The valve spool is maintained in the open position by the residual magnetism of the valve housing and spool even when power is no longer provided to the solenoid. Energizing the other solenoid moves the spool and valve to a closed position. The solenoids are digitally latched by short digital pulses provided by a microcontroller. The valve is therefore opened by providing a digital pulse of a short duration to one of the solenoids and closed by a digital pulse that is provided to the other solenoid. The valve may be opened by a plurality of pins. One of the pins may engage a stop so that the valve is initially opened with a relatively high force and then moved into the fully opened position with a lower force.