Variable lift operation of bistable electromechanical poppet valve actuator

The method of operating an electromechanical valve actuating device for an internal combustion engine in a partial lift mode, the valve actuating device actuating a valve movable between a closed position against a valve seat and a full open position away from the valve seat and comprising spring means effective to bias the valve toward a neutral position between the closed and open positions, permanent magnet means for each of the closed and full open positions effective to retain the valve in the respective closed or full open position as it approaches either and a coil associated with each of the permanent magnet means and effective, when supplied with an electric current, to produce a magnetic field superimposed on that of the respective permanent magnet means and thus effective to modify the magnetic attraction of the respective permanent magnet means on the valve, the method comprising the following steps:

• establishing the valve in its closed position;
• providing, at a predetermined valve opening time, an opening electric current to the coil associated with the permanent magnet means for the closed position of the valve in direction to reduce the magnetic field thereof and allow the spring means to accelerate the valve toward the fully open position;
• stopping the opening electric current before the valve reaches its full open position;
• and
• providing, when the opening electric current is stopped and before the valve reaches its full open position, a closing electric current to one of the coils associated with the permanent magnet means for the full open and closed positions of the valve in direction and amount to modify the magnetic field thereof to cause the valve to be returned to its closed position, the valve open duration being determined at least in part by the time duration between the initiation of the opening electric current and the initiation of the closing electric current.