Turbocharger



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 diesel 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.


Turbocharger with the waste gate 
(12) Actuating lever (13) Wastegate actuator (14) Line (boost pressure)


(14) Line (boost pressure) (15) Waste gate solenoid

When the load on the tractor 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 waste gate is a valve that allows exhaust gas to bypass the turbine wheel of the turbocharger. The operation of the waste gate 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 waste gate 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 waste gate actuator. 

When high boost pressure is needed for the engine performance, a signal is sent from the ECM to the waste gate 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 waste gate. 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 waste gate 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 flows to the lubricating oil inlet port (5) passes through the center of the turbocharger which retains the bearings. The oil exits the turbocharger from the lubricating oil outlet port (10) and returns to the oil pan.