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| Illustration 1 | g00451885 |
Air Inlet and Exhaust System Schematic (1) Inlet manifold (2) Aftercooler core (3) Air line (4) Exhaust outlet from turbocharger (5) Turbine side of turbocharger (6) Compressor side of turbocharger (7) Air cleaner | |
The engine components of the air inlet and exhaust system control the quality of air and the amount of air that is available for combustion. The components of the air inlet and exhaust system are the following components:
- Air cleaner
- Turbocharger
- Aftercooler
- Cylinder head
- Valves and valve system components
- Piston and cylinder
- Exhaust manifold
The turbocharger compressor wheel pulls inlet air through the air cleaner and into the air inlet. The air is compressed and heated to about 150°C (300°F) before the air is forced to the aftercooler. The air flows through the aftercooler core (2) and the temperature of the compressed air lowers to about 43°C (110°F). The combustion efficiency increases because of the cooler inlet air. This helps to provide lowered fuel consumption and increased horsepower output. The aftercooler core (2) is a separate cooler core that is mounted in front of the engine radiator. The engine fan and the ram effect of the vehicle's forward motion moves ambient air across both cores. This cools the turbocharged inlet air and the engine coolant.
Air is forced from the aftercooler into the inlet manifold (1). The airflow from the inlet port into the cylinders is controlled by inlet valves.
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| Illustration 2 | g00451886 |
Air Inlet And Exhaust System (2) Aftercooler core (4) Exhaust outlet (5) Turbine side of turbocharger (6) Compressor side of turbocharger (7) Exhaust manifold (8) Exhaust valve (9) Inlet valve (10) Air inlet | |
Each cylinder has two inlet valves (9) and two exhaust valves (8) in the cylinder head. The inlet valves open when the piston moves downward on the inlet stroke. When the inlet valves open, cooled compressed air from the inlet port within the inlet manifold is pulled into the cylinder. The piston begins to move up on the compression stroke when the inlet valves close. The air in the cylinder is compressed and the fuel is injected into the cylinder when the piston is near the top of the compression stroke. Combustion begins when the fuel mixes with the air. The force of combustion pushes the piston downward on the power stroke. The exhaust valves open and the exhaust gases are pushed through the exhaust port into the exhaust manifold (7). After the piston makes the exhaust stroke, the exhaust valves close and the cycle begins again.
Exhaust gases from the exhaust manifold flow into the turbine side of the turbocharger (5). This causes the turbocharger turbine wheel to turn. The turbine wheel is connected to the shaft that drives the compressor wheel. Exhaust gases from the turbocharger pass through the exhaust outlet (4), through a muffler, and through an exhaust stack.
Turbocharger
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| Illustration 3 | g00291064 |
Turbocharger (Typical Example) (1) Pipe (2) Exhaust manifold (3) Turbocharger | |
The turbocharger (3) is mounted to the exhaust manifold (2) of the engine. All of the exhaust gases go from the exhaust manifold through the turbocharger.
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| Illustration 4 | g00291085 |
Turbocharger (4) Air inlet (5) Compressor housing (6) Compressor wheel (7) Bearing (8) Oil inlet port (9) Bearing (10) Turbine housing (11) Turbine wheel (12) Exhaust outlet (13) Oil outlet port (14) Exhaust inlet | |
The exhaust gases enter the turbocharger and the blades of the turbocharger turbine wheel are turned. Because the turbocharger turbine wheel is connected by a shaft to the turbocharger compressor wheel, the turbine wheel and the compressor wheel turn at very high speeds. The rotation of the compressor wheel pulls clean air through the compressor housing air inlet. The action of the compressor wheel blades causes a compression of the inlet air. This compression gives the engine more power. The engine gets more power because the engine is able to burn more air and more fuel during combustion.
When the load on the engine increases or when a greater engine speed is desired, additional fuel is injected into the cylinders. This creates more exhaust gases, which causes the turbine wheel and the compressor wheel to turn faster. Additional air is forced into the engine as the compressor wheel turns faster. The increased flow of air provides more power to the engine. The engine gets more power because the engine is able to burn additional fuel with greater efficiency.
The bearings (7) and (9) in the turbocharger use engine oil that is under pressure for lubrication. The lubrication oil for the bearings flows through an oil inlet port (8) and into the inlet port in the center section of the cartridge. The oil exits the turbocharger through an oil outlet port (13) and through an oil drain line. The oil then returns to the engine lubrication system.
Valves And Valve Mechanism
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| Illustration 5 | g00327369 |
Valve System Components (1) Inlet valve bridge (2) Inlet rocker arm (3) Push rod (4) Rotocoil (5) Inner valve springs and outer valve springs (6) Valve guide (7) Inlet valves (8) Lifter (9) Camshaft | |
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| Illustration 6 | g00521092 |
Valve System Components (1) Inlet valve bridge (2) Inlet rocker arm (7) Inlet valves (10) Exhaust rocker arm (11) Exhaust valve bridge (12) Exhaust valves | |
The inlet and exhaust valves are opened and closed by the movement of the following components:
- crankshaft
- camshaft
- lifters
- rocker arms
- bridges
- valve springs
Rotation of the crankshaft causes rotation of the camshaft. The camshaft gear is driven by a gear on the front of the crankshaft. The gear is also used to time the camshaft to the crankshaft. As camshaft (9) turns, the camshaft lobes cause lifters (8) to go up and down. The lifters move push rods (3). The push rods then move inlet rocker arms (2) and exhaust rocker arms (10). Movement of the rocker arms will move the inlet valve bridge (1) and exhaust valve bridge (11). The bridges move on the dowels that are mounted in the cylinder head.
These bridges allow one rocker arm to either open or either close two valves at the same time. The valves are either the inlet valves or the exhaust valves at the same time. There are two inlet valves and two exhaust valves in each cylinder. Two valve springs (5) for each valve hold the valves in the closed position when the lifters move down.
Rotocoil assemblies (4) cause the valves to have rotation while the engine is running. This rotation of the valves keeps the deposits of carbon on the valves to a minimum. The Rotocoils give the valves a longer service life.