System Description
The BorgWarner™ dual-scroll turbocharger incorporates a wastegate that is controlled by the engine control module (ECM) by means of a pulse width modulation (PWM) solenoid, to regulate the pressure ratio of the compressor. An ECM controlled compressor bypass valve, which uses a remotely mounted solenoid, is integrated into the unit to prevent compressor surging and damage from vibrations by opening during abrupt closed throttle conditions. The bypass valve is open during closed throttle deceleration conditions to allow air to recirculate in the turbocharger and maintain compressor speed. The valve closes during open throttle commands, to optimize turbo response.
Front wheel drive platforms also incorporate a bypass valve vacuum tank. The purpose of the tank is to provide an instant source of vacuum to the bypass valve, when it is commanded open by the ECM. This results in less pressure buildup under closed throttle conditions, thereby reducing compressor noise and surge.