Schaeffler introduces a continuously variable valve timing control with an electric motor that enables operation during cold starts

12/21/16 / Schaeffler

Schaeffler introduces a continuously variable valve timing control with an electric motor that enables operation during cold starts

An Electric Cam Phaser is future technology used for optimizing valve timing based on engine conditions. A function that has become essential for improving fuel efficiency and CO2 reduction, reducing hydrocarbon emissions, raising drivability and output performance. In the early 1980’s variable valve timing systems were introduced which controlled the timing in steps, this was later replaced by continuously variable valve timing control system in the mid 1990’s. The Electric Cam Phaser was introduced in 2016 by Schaeffler, this offers electric motor control, of the continuously variable valve timing control system rather than hydraulic control.

Most of the variable valve control is regulated electrically, but even today’s modern designs are configured so the timing of the variable valve mechanism changed the movement of the spline along the camshaft through hydraulic pressure. A drawback of hydraulic control is that is doesn’t provide enough pressure needed for a cold engine start.

However, Schaeffler were not the first in developing the Phaser, Denso reached this milestone all the way back in 2006. The housing of Denso’s Phaser projects from the side of the engines cylinder head increasing the size. The Electric Cam Phaser from Schaeffler separates its controller to allow for easier installation. The compact gearbox also makes it as easy to install as a conventional hydraulic system.

So with all these advantages have there been any credible results from electrification? The answer is yes, the waveform at the engine start in the 3rd image shows that the valve shifted to the cam phase as dictated by the valve timing control before combustion of the engine took place.

The 4th image shows the relationship between the engine speed and the cam phasing velocity of the Electric Cam Phaser and the Hydraulic Cam Phaser (HCP), it shows the phasing velocity of the HCP drops in low ranges due to decompression, but rises again as the engine speed increases. In contrast, the electric phaser maintains necessary cam phasing velocities from the idling range through to high ranges.