A turbocharger uses the exhaust gases to drive a turbine wheel which drives a compressor. The compressor increases the pressure and density of the charge in the engine's cylinders. This will increase the power of the engine above a naturally aspirated engine.
The turbocharger consists of a single stage axial flow turbine and a centrifugal air compressor that is connected by a single rotor shaft that is supported on inboard bearings.
The exhaust gas that is discharged from the engine cylinders enters the inlet housing for the turbine. The exhaust gas is accelerated through a nozzle ring into the turbine blades. The turbine blades then turn the rotor shaft. The gases then pass through the outlet housing for the turbine to an exhaust pipe.
The air that is required by the engine is drawn through the inlet housing for the compressor. The air is then compressed by compressor wheel and a diffuser into the outlet housing for the compressor. The air is then forced into the engine's combustion chamber.
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| Illustration 1 | g06597683 |
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(1) Inlet housing for the compressor
(2) Bearing (3) Bearing (4) Outlet housing for the turbine (5) Inlet housing for the turbine (6) Inlet housing for the compressor (7) Turbine wheel (8) Compressor wheel | |
The turbocharger is an assembly of four housings that are bolted together. A single stage axial flow turbine and a centrifugal air compressor is mounted on a single shaft.
The turbocharger's lubrication is supplied from the engine.
Outlet Housing for the Turbine
The outlet housing for the turbine is cooled by air. The outlet housing for the turbine is attached to the main housing. The outlet housing for the turbine collects the exhaust gas from the turbine. The exhaust gas is directed to the exhaust outlet. The outlet housing for the turbine can be fully indexed. This allows a wide range of positions for the housing. The shroud ring is also attached to the housing.
The inlet housing for the turbine is cooled by air. The housing is attached to the outlet housing for the turbine at one end. The other end is attached to the exhaust piping for the engine. The inlet housing for the turbine also supports the nozzle ring.
The cartridge assembly is made from following components: main housing, compressor outlet housing, inlet housing for the compressor, rotor assembly and bearings. The cartridge can be removed from the engine as an assembly. The turbine inlet and outlet housings remain attached to the engine. This allows the cartridge assembly to be removed for service. Service or replacement of the nozzle can be performed while the cartridge is removed.
The main housing forms the base for the other housing to be attached. The forward mounting foot is part of the main housing and mounts to the engine. The mounting foot is also the point for the inlet and the outlet for the lubrication oil. The lubrication oil can be routed through the mounting foot or through piping that is attached to the mounting foot.
A seal plate is attached to the main housing and machined grooves form part of a labyrinth seal. Mating grooves on the back of the compressor wheel form the other part of the labyrinth seal. A controlled air supply is forced across the labyrinth seal. The air will pressurize the seal ring for the compressor. The air is then travels through passages in the housing to the turbine end. The air cools the space between the main housing and the cone. The air pressurizes the space between the main housing and the cone. The air then pressurizes the seal rings for the turbine. This prevents oil leakage and exhaust gases from entering. The air then passes across the face of the turbine wheel. The air then cools the turbine wheel before the air travels into the turbine outlet.
This rotor assembly consists of a solid steel shaft. One end of the shaft is an interference fit onto the hub of the turbine wheel.
Do not attempt to separate the turbine wheel from the shaft.
A preset seal ring is fit into the hub of the compressor wheel and two preset ring seals are fit at the turbine end of the shaft. The seals prevent oil leakage and exhaust gases from entering.
The rotor and seal rings are supported by the compressor and the turbine end bearing housings. Each major component of the rotor assembly is dynamically balanced before assembly. After the assembly is complete, the rotor is checked and the rotor is balanced without the thrust collar.
There are two bearing housings. The bearing housings are located in the main housing. The bearing housings are used to locate the following bearings: journal bearing for the turbine, journal bearing for the compressor and minor thrust bearings. The bearing housings transfer the lubrication oil to the bearings and from the bearings.
The major thrust bearing is fit onto the inboard end of the compressor end bearing housing. This presets the position of the rotor assemblies. No adjustments are required. Positions of the seal ring automatically adjust to the rotor's position.
The bearings are lubricated from the main engine oil supply.
Outlet Housing for the Compressor
Air is drawn into the inlet housing for the compressor, which is attached to the outlet housing for the compressor. The air is discharged to the engine by the compressor wheel and the diffuser through a flanged connection.