ENGINE AR 7N6739 - Caterpillar

Illustration 1 g01456369
(1) Exhaust manifold
(2) Air inlet heater
(3) Aftercooler core
(4) Exhaust valve
(5) Inlet valve
(6) Air inlet
(7) Exhaust outlet
(8) Compressor side of turbocharger
(9) Turbine side of turbocharger The 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 Inlet air is pulled through the air cleaner into air inlet (6) by turbocharger compressor wheel (8). The air is compressed and heated to about 150 °C (300 °F) before the air is forced to the aftercooler (3). As the air flows through the aftercooler the temperature of the compressed air lowers to about 43 °C (110 °F). Cooling of the inlet air increases combustion efficiency. Increased combustion efficiency helps achieve the following benefits:
Lower fuel consumption
Increased horsepower outputFrom the aftercooler, air is forced into the inlet manifold. Air flow from the inlet chambers into the cylinders is controlled by inlet valves (5). There are two inlet valves and two exhaust valves (4) for each cylinder. The inlet valves open when the piston moves down on the intake stroke. When the inlet valves open, cooled compressed air from the inlet port is pulled into the cylinder. The inlet valves close and the piston begins to move up on the compression stroke. The air in the cylinder is compressed. When the piston is near the top of the compression stroke, fuel is injected into the cylinder. The fuel mixes with the air and combustion starts. During the power stroke, the combustion force pushes the piston downward. The exhaust valves open and the exhaust gases are pushed through the exhaust port into exhaust manifold (1) as the piston rises on the exhaust stroke. After the exhaust stroke, the exhaust valves close and the cycle starts again. The complete cycle consists of four strokes:
Inlet
Compression
Power
ExhaustExhaust gases from exhaust manifold (1) enter the turbine side of the turbocharger in order to turn turbocharger turbine wheel (9). The turbine wheel is connected to the shaft that drives the compressor wheel. Exhaust gases from the turbocharger pass through exhaust outlet (7), a muffler and an exhaust stack.Turbocharger
Illustration 2 g01456229
Cross section of turbocharger
(10) Compressor wheel housing
(11) Oil inlet port
(12) Bearing
(13) Turbine wheel housing
(14) Turbine wheel
(15) Air inlet
(16) Exhaust outlet
(17) Compressor wheel
(18) Bearing
(19) Oil outlet port
(20) Exhaust inlet The turbocharger is installed on the center section of the exhaust manifold. All the exhaust gases from the engine go through the turbocharger. The compressor side of the turbocharger is connected to the aftercooler by pipe.The exhaust gases enter turbine housing (13) through exhaust inlet (20). The exhaust gases then push the blades of turbine wheel (14). The turbine wheel is connected by a shaft to compressor wheel (14).Clean air from the air cleaners is pulled through compressor housing air inlet (15) by the rotation of compressor wheel (17). The action of the compressor wheel blades causes a compression of