21709796 Volvo.Penta Cover

Illustration 1 g01205681
Air inlet and exhaust system
(1) Exhaust manifold
(2) Electronic unit injector
(3) Glow plug
(4) Inlet manifold
(5) Aftercooler core (if equipped)
(6) Exhaust outlet
(7) Turbine side of turbocharger
(8) Compressor side of turbocharger
(9) Air inlet from the air cleaner
(10) Inlet valve
(11) Exhaust valve 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 air inlet and exhaust system consists of the following components:
Air cleaner
Turbocharger
Aftercooler
Inlet manifold
Cylinder head, injectors and glow plugs
Valves and valve system components
Piston and cylinder
Exhaust manifoldAir is drawn in through the air cleaner into the air inlet of the turbocharger (9) by the turbocharger compressor wheel (8). The air is compressed and heated to about 150 °C (300 °F) before the air is forced to the aftercooler (5). As the air flows through the aftercooler the temperature of the compressed air lowers to about 50 °C (120 °F). Cooling of the inlet air increases combustion efficiency. Increased combustion efficiency helps achieve the following benefits:
Lower fuel consumption
Increased horsepower output
Reduced particulate emissionFrom the aftercooler, air is forced into the inlet manifold (4). Air flow from the inlet manifold to the cylinders is controlled by inlet valves (10). There are two inlet valves and two exhaust valves 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 forced into the cylinder. The complete cycle consists of four strokes:
Inlet
Compression
Power
ExhaustOn the compression stroke, the piston moves back up the cylinder and the inlet valves (10) close. The cool compressed air is compressed further. This additional compression generates more heat. Note: If the cold starting system is operating, the glow plugs (3) will also heat the air in the cylinder.Just before the piston reaches the TC position, the ECM operates the electronic unit injector. Fuel is injected into the cylinder. The air/fuel mixture ignites. The ignition of the gases initiates the power stroke. Both the inlet and the exhaust valves are closed and the expanding gases force the piston downward toward the bottom center (BC) position .From the BC position, the piston moves upward. This initiates the exhaust stroke. The exhaust valves open. The exhaust gases are forced through the open exhaust valves into the exhaust manifold.Exhaust gases from exhaust manifold (1) enter the turbine side of the turbocharger in order to turn turbocharger turbine wheel (7). The turbine wheel is connected to the shaft that drives the compressor wheel. Exhaust gases from the turbocharger pass through exhaust outlet (6), a silencer and an exhaust pipe.Turbocharger
Illustration 2 g01263770
Turbocharger
(1) Air intake
(2) Compressor housing
(3) Compressor wheel
(4) Bearing
(5) Oil inlet port
(6) Bearing
(7) Turbine housing
(8) Turbine wheel
(9) Exhaust outlet
(10) Oil outlet port
(11) Exhaust inlet The turbocharger is mounted on the outlet of the exhaust manifold in one of two positions on the right side of the engine, toward the top of the engine or to the side of the engine. The exhaust gas from the exhaust manifold enters the exhaust inlet (11) and passes through the turbine housing (7) of the turbocharger. Energy from the exhaust gas causes the turbine wheel (8) to rotate. The turbine wheel is connected by a shaft to the compressor wheel (3).As the turbine wheel rotates, the compressor wheel is rotated. This causes the intake air to be pressurized through the compressor housing (2) of the turbocharger.
Illustration 3 g01459759
Typical turbocharger with the wastegate
(12) Actuating lever
(13) Wastegate actuator
(14) Line (boost pressure)
(15) Wastegate solenoid 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, air is compressed to a higher pressure and more air is forced into the cylinders. The increased flow of air into the cylinders allows the fuel to be burnt with greater efficiency. This produces more power.A wastegate is installed on the turbine housing of the turbocharger. The wastegate is a valve that allows exhaust gas to bypass the turbine wheel of the turbocharger. The operation of the wastegate is dependent on the pressurized air (boost pressure) from the turbocharger compressor. The boost pressure acts on a diaphragm that is spring loaded in the wastegate actuator which varies the amount of exhaust gas that flows into the turbine.If a wastegate solenoid (15) is installed, then the wastegate is controlled by the engine Electronic Control Module (ECM). The ECM uses inputs from a number of engine sensors to determine the optimum boost pressure. This will achieve the best exhaust emissions and fuel consumption at any given engine operating condition. The ECM controls the solenoid valve, which regulates the boost pressure to the wastegate actuator.When high boost pressure is needed for the engine performance, a signal is sent from the ECM to the wastegate solenoid . This causes low pressure in the air inlet pipe (14) to act on the diaphragm within the wastegate actuator (13). The actuating rod (12) acts upon the actuating lever to close the valve in the wastegate. When the valve in the wastegate is closed, more exhaust gas is able to pass over the turbine wheel. This results in an increase in the speed of the turbocharger.When low boost pressure is needed for the engine performance, a signal is sent from the ECM to the wastegate solenoid. This causes high pressure in the air inlet pipe (14) to act on the diaphragm within the wastegate actuator (13). The actuating rod (12) acts upon the actuating lever to open the valve in the wastegate. When the valve in the wastegate is opened, more exhaust gas from the engine is able to bypass the turbine wheel, resulting in an decrease in the speed of the turbocharger.The shaft that connects the turbine to the compressor wheel rotates in bearings (4 and 6). The bearings require oil under pressure for lubrication and cooling. The oil that