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| Illustration 1 | g00742289 |
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Typical Example (1) Tube from the aftercooler (2) Exhaust bypass valve (3) Breather | |
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| Illustration 2 | g00812973 |
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Section view of an exhaust bypass valve (4) Opening for the tube from the aftercooler (5) Diaphragm (6) Spring (7) Adjusting screw (8) Valve (9) Exhaust gas to the turbocharger (10) Exhaust gas to the exhaust elbow (11) Opening for the breather | |
Valve (8) is activated directly by a pressure differential.
Atmospheric pressure is exerted through opening (11) for breather (3) on one side of diaphragm (5). Force from spring (6) is on the same side of the diaphragm. The force of the spring is adjusted with adjusting screw (7).
Boost pressure is exerted on the other side of the diaphragm through opening (4) for tube (1) from the aftercooler. On the same side of the diaphragm, exhaust gas exerts pressure on valve (8).
When the force of the spring plus the atmospheric pressure is overcome by boost pressure, valve (8) opens in order to divert some exhaust gas (9) from the turbocharger to the exhaust elbow (10). This prevents the turbocharger from providing too much boost pressure.
Excessive boost pressure can result in overloading of the engine, overheating, detonation, and turbocharger surge. The amount of exhaust gas to the turbine wheel is maintained in order to provide the correct boost pressure. The boost pressure determines the throttle angle at full load operation.
A throttle angle of approximately 70 degrees is recommended for full load operation.
Under constant load conditions, the exhaust bypass valve maintains a stable position.
The exhaust bypass valve is cooled with engine coolant.