Variable swirl control actuator consists of DC motor and motor position sensor(potentiometer) which detects the position of swirl valve.

As closing one intake port out of two at idle and below 3000RPM, swirl effect is taken on intake air.

This swirl effect increases air flow rate.

However, because air flow rate is too high, swirl effect is neglectable thus, swirl valve is opened for efficiency of intake air.

To prevent swirl valve and shaft form being stuck by foreign metarial, and to learn max opening and closing position of swirl valve, it is fully opened and closed twice at turning engine OFF.

※ Swirl

The air flow which indicates Intake air swirls with respect to the axis passing through the centre of piston with length-direction by intake port which is eccentric from the centre of combustion chamber.

Fig.1) Close control signal waveform of VSA

Fig.2) Opne control signal waveform of VSA

Fig.3) Learning waverform of VSA position when IG ON → OFF