TWO-STAGE TURBO CONTROL [SKYACTIV-D 2.2]

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Outline

•  By switching the air charging between the large-type turbocharger and small-type turbocharger, driveability under a wide range of conditions and emission performance have been improved.
•  The following 3 solenoid valves are driven according to the engine operation conditions to switch the air charging between the large-type turbocharger and small-type turbocharger.
―  Compressor bypass solenoid valve
•  The compressor bypass valve opens/closes according to the on/off signal from the PCM.
―  Regulating solenoid valve
•  The regulating valve opens/closes according to the duty signal from the PCM.
―  Wastegate solenoid valve
•  The wastegate valve opens/closes according to the duty 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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OFF: No energization
ON: Energization (on control)

Item

Operation conditions

Compressor bypass solenoid valve

Regulating solenoid valve*1

Wastegate solenoid valve*2

Turbo charging condition
(1) Engine start/partial warm-up range
ON (open)
Duty 0% (open)
Duty 0% (open)
No turbo charging
(2) Low engine speed range
OFF (closed)
Duty 50—95% (closed)
Duty 60—95% (closed)
Two-stage turbo charging
(3) Middle engine speed range
OFF (closed)
Duty 0 to 95% (closed ↔ open)
Duty 60—95% (closed)
Single-stage turbo charging to two-stage turbo charging based on large-type turbocharger
(4) High engine speed range
ON (open)
Duty 0% (open)
Duty 60—95% (closed)
Single-stage turbo charging based on large-type turbocharger
(5) Air charging control range at wastegate valve
ON (open)
Duty 0% (open)
Duty 0 to 95% (closed ↔ open)
Single-stage turbo charging based on no turbo charging to large-type turbocharger

*1  :The required duty value to close the regulating valve is 50%, however, if it is difficult to close the regulating valve because of the exhaust gas pressure, the PCM increases the duty value.
*2  :The required duty value to close the wastegate valve is 60%, however, if it is difficult to close the wastegate valve because of the exhaust gas pressure, the PCM increases the duty value.
•  For details on the two-stage turbo control, refer to the AIR CHARGING SYSTEM. (See AIR CHARGING SYSTEM [SKYACTIV-D 2.2].)