TWO-STAGE TURBO CONTROL [SKYACTIV-D 2.2]

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Outline

•  The PCM controls the boost pressure efficiently in the range from low engine speed to high engine speed, achieving low emission, low fuel consumption, high torque, and high response according to the following operations.
―  Either one of the large-type and small-type turbochargers is used correctly
―  The opening angle of the variable nozzles for the large-type turbocharger is adjusted correctly
•  The PCM operates the following 3 actuators to obtain optimum boost pressure according to the engine operation conditions.
―  Compressor bypass solenoid valve
•  The compressor bypass valve opens/closes according to the on/off signal from the PCM.
―  Regulating valve actuator
•  The regulating valve is controlled according to the duty signal from the PCM.
―  Variable turbine geometry turbocharger actuator
•  The variable nozzle is controlled according to the signal from the PCM.

Block diagram

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Operation

•  The two-stage turbocharger control is divided between the large and small-type turbochargers in mainly 5 ranges.
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Item

Operation conditions

Compressor bypass valve

Regulating valve

Variable nozzle

Turbo charging condition
(1) Low engine speed range
Fully closed
Fully closed
Fully open*1
Single-stage turbo charging based on small-type turbocharger
(2) Middle engine speed range
Fully closed
Fully open*1
Fully open*1
Two-stage turbo charging
(3) High engine speed range
Fully open
Fully open
Open↔Fully open
Single-stage turbo charging based on large-type turbocharger

*1  :The opening angle changes depending on the target boost pressure/exhaust pressure
•  For details on the two-stage turbo control, refer to the AIR CHARGING SYSTEM. (See AIR CHARGING SYSTEM [SKYACTIV-D 2.2].)