HORN 3N5762 - Caterpillar

Illustration 1 g01088763
Diagram of the electronic system for the compressor bypass group
The compressor bypass group enables the master Electronic Control Module (ECM) to maintain the desired boost pressure.
Illustration 2 g01088747
Top view
Flow of the compressed air/fuel mixture during opening of the compressor bypass group
(1) Actuator for the bypass valve
(2) Bypass valve The ECM monitors the boost pressure sensor. The ECM uses a map to determine the desired boost pressure for the operating conditions. The ECM compares the actual boost pressure to the desired boost pressure. The ECM sends a command signal to actuator (1) in order to modulate the boost pressure. This causes the actuator to move a shaft that is connected to a plate inside bypass valve (2).The bypass valve is connected before the throttle. Tubing is connected from the bypass valve to the inlets for the turbocharger compressors. When the bypass valve is opened, the compressed air/fuel mixture is diverted through the tubing away from the throttle. This reduces the boost pressure.The ECM is capable of modulating the bypass valve from a fully closed position to a fully opened position.The compressor bypass group is also operated during engine shutdown. This reduces the opportunity for a turbocharger surge during engine shutdown. Additionally, any air/fuel mixture that may have been trapped in the tubing is purged.