- Engine:
- 3616 (S/N: 1PD)
The turbocharger compressor bypass system can be controlled with the following devices:
- 150-7700 Tachometer (speed switch)
- 3600 Marine Monitoring System II MMS-II
- 3600 Generator Monitoring System GMS-II
- Customer supplied tachometer / speed switch
Please refer to Service Manual Module, RENR5851, "Specifications, System Operation, Testing and Adjusting" for the configuration settings of the 150-7700 Tachometer. Refer to Service Manual Module, RENR2490, "System Operation" for the settings of the MMS-II.
The turbocharger compressor bypass valve is installed on 3616 S/N:1PD
engines that have a rating of 6000 kW at 1020 RPM. The turbocharger compressor bypass valve optimizes the performance of the turbocharger throughout the entire engine RPM range.
The turbocharger is capable of producing boost pressures that are greater than the needs of the engine. Without the turbocharger compressor bypass valve, excessive boost pressure could build up in the air inlet manifold. Excessive boost pressure may result in a turbocharger surge. Severe damage to the turbocharger may result if the turbocharger goes into a surge. In order to prevent a turbocharger surge, a turbocharger compressor bypass valve is required in the air induction system.
The turbocharger compressor bypass valve allows noncooled inlet air from the upper housing of the aftercooler to flow into the exhaust manifolds. The turbocharger compressor bypass valve allows excess boost pressure to escape, rather than building pressure within the air inlet manifold. Opening the turbocharger compressor bypass valve reduces the opportunity for a turbocharger surge. The noncooled air from the aftercooler housing also provides a cooling effect to the exhaust manifolds.
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| Illustration 1 | g00848951 |
This is an illustration of the left side of the 3616 aftercooler. (1) Piping from the aftercooler housing (2) Bypass valve housing (3) Turbocharger compressor bypass valve (4) Aftercooler housing (5) Excess boost pressure is directed to the engine exhaust manifolds. | |
The correct operation of the turbocharger compressor bypass valve is critical to the effective operation of the engine.
Note: Do not operate the engine without a load with the compressor bypass valve open.
This can allow exhaust gases from the exhaust manifold to flow backward through the turbocharger compressor bypass valve and into the aftercooler. Exhaust gases could contaminate the aftercooler. Contamination may restrict the air flow through the aftercooler core. The restriction can cause poor engine performance. In some cases, the engine can overheat.
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| Illustration 2 | g00849572 |
This is an illustration of the Turbocharger Compressor Bypass Valve. (6) Valve (7) Bypass valve housing (8) Air inlet port (9) Diaphragm (10) Spring | |
The turbocharger compressor bypass valve is mounted in the bypass valve housing. The bypass valve housing is mounted to the aftercooler cover. The bypass valve is cooled with water from the aftercooler circuit.
Note: The turbocharger compressor bypass valve is a normally closed valve. The valve is held in the closed position by a spring within the bypass valve housing. A speed sensor is constantly monitoring the engine RPM. Setpoints that are based on the engine RPM control a solenoid that supplies pressurized air to the turbocharger compressor bypass valve. The bypass valve is pneumatically actuated by compressed air from the air start system.
The Sequence of Events for the Turbocharger Compressor Bypass Valve
As the engine accelerates from low idle to the rated speed of 1020 RPM, the following sequence of events occur:
- When the engine accelerates to 580 RPM the bypass control energizes the air solenoid valve after a 2 second delay.
- The energized solenoid valve allows air pressure to enter air inlet port (8) on turbocharger compressor bypass valve (3) .
- The air pressure that is supplied to the turbocharger compressor bypass valve overcomes the force of spring (10), and valve (6) opens.
- When the turbocharger compressor bypass valve is open, excess boost pressure is redirected into the exhaust manifolds.
- The turbocharger compressor bypass valve remains open when the engine is operating between 580 RPM and 960 RPM.
- When the engine accelerates to 960 RPM the air solenoid valve de-energizes after a 1/2 second delay. This will close the turbocharger compressor bypass valve.
The turbocharger compressor bypass valve remains closed from 960 RPM to the rated speed of 1020 RPM.
As the engine decelerates from rated speed of 1020 RPM toward low idle, the following sequence of events occur:
- The turbocharger compressor bypass valve remains closed from the rated speed of 1020 RPM until the engine decelerates to 960 RPM.
Note: The setpoint for the high RPM is 960 RPM. There is a hysteresis of 20 RPM that is programmed into the bypass control that occurs during deceleration.
- The engine continues to decelerate until the setpoint of 940 RPM is reached. The air solenoid valve energizes after a programmed 1/2 second delay.
- The energized solenoid valve allows air pressure to enter the air inlet port (8) on the turbocharger compressor bypass valve (3).
- The air pressure that is supplied to the valve overcomes the force of the spring (10), and the turbocharger compressor bypass valve opens.
- When the turbocharger compressor bypass valve is open, excess boost pressure is redirected into the exhaust manifolds.
- The turbocharger compressor bypass valve is open when the engine is decelerating between 560 RPM and 940 RPM.
Note: The setpoint for the low RPM is 580 RPM. There is a hysteresis of 20 RPM that is programmed into the bypass control that occurs during deceleration.
- When the engine decelerates to 560 RPM, the bypass control de-energizes the solenoid valve after a 2 second time delay.
- The de-energized solenoid valve releases the air pressure from air inlet port (8) on turbocharger compressor bypass valve (3). The turbocharger compressor bypass valve is closed by the force of the spring within the valve.