C15 and C18 – Turbocharger


(21) Air inlet

(22) Compressor housing

(23) Compressor wheel

(24) Bearing

(25) Oil inlet port

(26) Bearing

(27) Turbine housing

(28) Small path

(29) Balance valve chamber

(30) Large Path

(31) Turbine wheel

(32) Exhaust outlet

(33) Oil outlet port

The turbocharger is installed on the exhaust manifold. Most of the exhaust gases flow through the turbocharger. A metered amount of exhaust gases flow through the NRS system. The compressor side of the turbocharger is connected to the aftercooler by a pipe.

The exhaust gases go into turbine housing (27) through the exhaust inlet. The turbine housing of the turbocharger is of the asymmetric design. The asymmetric design consists of the turbine housing that has two different-sized paths for the exhaust to flow. Path (28) receives exhaust gas from cylinders one, two, and three. Path (30) receives exhaust gas from cylinders four, five, and six. The smaller path restricts the flow of the exhaust. This restriction helps force the exhaust gas through the NRS system to the intake manifold of the engine. The energy from the heat in the exhaust gases pushes the blades of turbine wheel (31). The turbine wheel is connected by a shaft to compressor wheel (23). The turbine housing also contains the exhaust balance valve and the actuator for the exhaust balance valve. The actuator for the exhaust balance valve receives boost pressure from the intake manifold. This boost pressure is first regulated by the solenoid for the exhaust balance valve. The exhaust balance valve solenoid will open allowing the boost pressure to act on the exhaust balance valve actuator if the valve needs to open. The actuator then opens the exhaust balance valve. The exhaust balance valve allows the flowing exhaust gas from the small path of the turbine housing to enter the large path. This action causes less exhaust gas to act on the turbine wheel from the smaller flow path. This action slows down the speed of the turbine wheel in order to protect the turbocharger. A secondary effect is reduced flow through the NOx Reduction System (NRS).

Clean air from the air cleaners is pulled through compressor housing air inlet (21) by the rotation of compressor wheel (23). The action of the compressor wheel blades causes a compression of the inlet air. This compression gives the engine more power by allowing the engine to burn more air and more fuel during combustion.

When the load on the engine increases, more fuel is injected into the cylinders. The combustion of this additional fuel produces more exhaust gases. The additional exhaust gases cause the turbine and the compressor wheels of the turbocharger to turn faster. As the compressor wheel turns faster, more air is forced into the cylinders. The increased flow of air gives the engine more power by allowing the engine to burn the additional fuel with greater efficiency.

Bearings (24) and (26) for the turbocharger use engine oil under pressure for lubrication. The oil comes in through oil inlet port (25). The oil then goes through passages in the center section in order to lubricate the bearings. Oil from the turbocharger goes out through oil outlet port (33) in the bottom of the center section. The oil then goes back to the engine lubrication system.

Posted in C18

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