Electromagnetic valve actuator system includes monitor sensing movement and enabling control of coil current as valve approaches seating

摘要

The electromagnetic actuator system for a valve includes a ferromagnetic circuit within which a ferromagnetic plate is moved. This is attached to the valve rod. The current supplied to the operating coil is varied as a function of time, once the valve movement has passed a certain fraction of full displacement, in order to control the speed at which the valve strikes its seating. The electromagnetic actuator system for an internal combustion engine valve includes a ferromagnetic circuit defining an axial space within which a ferromagnetic plate is moved. This is attached to the rod moving the valve between two extreme positions. Springs are provided to return the valve to the mid position between the two extremes. A coil is used to apply a magnetic force to move the plate to either of the extreme positions. During closure of the valve, the displacement of the ferromagnetic plate is monitored. When the displacement attains a first fraction of the full value (x2) the coil is supplied with current according to a time-dependent function. When the displacement attains a second fraction of the full value (x3) the current is supplied according to a second function to ensure a low speed approach as the valve reaches its seat.