Positive Crankcase Ventilation
In a supercharged engine, since the negative pressure in the intake manifold is insufficient, the blow-by gas in the crankcase cannot be sufficiently ventilated with a usual PCV valve only. The negative pressure generated even in the supercharging range can be used to compensate the range where the PCV valve does not work by closing the admission valve which is adopted between the airflow sensor and the turbocharger.
Ventilation gas flow when not supercharging. Blow-by gas flows from the PCV valve to the intake manifold, but it does not flow from the one way valve to the supercharging ventilation piping.
Ventilation gas flow when not supercharging. Blow-by gas does not flow from the PCV valve to the intake manifold due to the positive pressure of the intake manifold. It returns to the intake manifold through the "supercharging ventilation pipe" due to the negative pressure of the admission valve.