3516E Generator Set Engine Caterpillar

The components of the air inlet and exhaust system control the quality and the amount of air that is available for combustion. There are separate turbochargers and exhaust manifolds on each side of the engine. The inlet manifold is a series of elbows that connect the aftercooler chamber to the inlet ports (passages) of the cylinder heads. There is one camshaft in each side of the block. The two camshafts control the movement of the valve system components.

Illustration 1	g01188937
Air Inlet And Exhaust System (1) Exhaust manifold (2) Air-to-air aftercooler (ATAAC) (3) Engine cylinder (4) Air inlet (5) Turbocharger compressor wheel (6) Turbocharger turbine wheel (7) Exhaust outlet

Clean inlet air from the air cleaners is pulled through air inlet (4) into the turbocharger compressor by compressor wheel (5). The rotation of the compressor wheel compresses the air. The rotation of the turbocharger compressor wheel then forces the air through a tube to the air-to-air aftercooler (ATAAC) (2). The ATAAC lowers the temperature of the compressed air before the air enters the inlet chamber in each cylinder head. Air flow from the inlet chamber into the cylinder heads is controlled by the inlet valves.

There are two inlet valves and two exhaust valves for each cylinder. Refer to Systems Operation, "Valve Mechanism". The inlet valves open when the piston moves down on the inlet stroke. The cooled, compressed air is pulled into the cylinder from the inlet chamber.

The inlet valves close and the piston starts to move up on the compression stroke. 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. The force of the combustion pushes the piston downward on the power stroke. When the piston moves upward again, the piston is on the exhaust stroke. The exhaust valves open and the exhaust gases are pushed through the exhaust port into exhaust manifold (1). After the piston makes the exhaust stroke, the exhaust valves close and the cycle starts again.

Exhaust gases from exhaust manifold (1) go into the turbine side of the turbocharger. The exhaust gases cause turbine wheel (6) to turn. The turbine wheel is connected to the shaft that drives the turbocharger compressor wheel (5). The exhaust gases exit through exhaust outlet (7).

Air Inlet And Exhaust System

Illustration 2	g02793277
Air Inlet And Exhaust System (1) Muffler (2) From air filters (3) Rear turbocharger (4) Exhaust (5) Front turbocharger (6) ATAAC (7) Intake manifold

This illustration is a schematic showing the air flow from the air filters to the mufflers on the 3516E engine.

The turbochargers are driven by the exhaust (4) from the cylinders which enters the turbine side of the turbochargers (3). The exhaust gas flows through the turbochargers, the exhaust piping, and the mufflers (1).

The clean air from the air filters (2) enters the compressor side of the turbochargers. The compressed air from the turbochargers flows to the aftercooler. Illustration 2 shows the ATAAC cores for the engine. After the air is cooled by the aftercoolers, the air flows through the intake manifold (7) to the cylinders and combines with the fuel for combustion.