BOOST
PRESSURE CONTROL
System Configuration Diagram
The engine-ECU sends a signal to the variable geometry
solenoid valve. The signal is the value required for the variable nozzle setting. The variable geometry
solenoid valve adjusts the position of the variable nozzle respectively and the speed changes results
from the different angles. The boost pressure is increased or reduced.
The boost pressure works depending on the torque demand. To control the boost pressure,
signals from the boost pressure sensor are used.
When the engine speed is low, the engine-ECU closes the variable nozzle by actuating the
variable geometry solenoid valve. Then the characteristic of boost pressure becomes a low speed
type, and the boost pressure suddenly rises from a low speed.
When the engine speed is high, the engine-ECU opens the variable nozzle by actuating
the variable geometry solenoid valve. Then the characteristic of boost pressure becomes a high
speed type, and the boost pressure is maintained appropriately.
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