3B2-65017-0 Tohatsu PUMP CASE LOWER

Illustration 1 g02720982
Air inlet and exhaust system
(1) Aftercooler core
(2) Air filter
(3) Diesel particulate filter
(4) Turbocharger
(5) Wastegate actuator
(6) Boost pressure chamber
(7) Exhaust gas valve (NRS)
(8) Wastegate regulator
(9) Exhaust cooler (NRS)
(10) Inlet manifold
(11) Throttle 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
Exhaust cooler (NRS)
Exhaust gas valve (NRS)
Turbocharger
Aftercooler
Inlet manifold
Cylinder head, injectors, and glow plugs
Valves and valve system components
Piston and cylinder
Exhaust manifold
Diesel oxidation catalyst
Diesel particulate filter
Throttle valveAir is drawn in through the air cleaner into the air inlet of the turbocharger by the turbocharger compressor wheel. The air is compressed to a pressure of about 150 kPa (22 psi) and the compression heats the air to about 120° C (248° F) before the air is forced to the aftercooler. As the air flows through the aftercooler the temperature of the compressed air lowers to about 55° C (131° F). Cooling of the inlet air assists the combustion efficiency of the engine. Increased combustion efficiency helps achieve the following benefits:
Lower fuel consumption
Increased power output
Reduced NOx emission
Reduced particulate emissionFrom the aftercooler, air is forced into the inlet manifold. Air flow from the inlet manifold to the cylinders is controlled by inlet valves. There is one inlet valve and one exhaust valve for each cylinder. The inlet valve opens when the piston moves down on the intake stroke. When the inlet valve opens, 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 valve closes. The cool compressed air is compressed further. This additional compression generates more heat.Note: If the cold starting system is operating, the glow plugs will also heat the air in the cylinder.Just before the piston reaches the top center (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 valve opens. The exhaust gases are forced through the open exhaust valve into the exhaust manifold.
Illustration 2 g02720984
Typical example
The NOx Reduction System (NRS) operates with the transfer of the hot exhaust gas from the exhaust manifold to the assembly of the exhaust gas valve.The assembly of the exhaust gas valve consists of an exhaust gas valve and an electronically controlled actuator.As the electronically controlled actuator (7) starts to open the flow of exhaust gas from the exhaust gas valve mixes with the air flow from the charge air aftercooler. The mixing of the exhaust gas and the air flow from the charge air aftercooler reduces the oxygen content of the gas mixture. This results in a lower combustion temperature, so decreases the production of NOx.As the demand for more exhaust gas increases the electronically controlled actuator opens further. The further opening of the actuator increases the flow of exhaust gas from the exhaust gas valve. As the demand for exhaust gas decreases, the electronically controlled actuator closes. This decreases the flow of exhaust gas from the exhaust gas valve.The hot exhaust gas is then cooled in the exhaust cooler (6). The cooled gas then travels from the exhaust cooler (6) to the inlet manifold.Exhaust gases from the exhaust manifold enter the inlet of the turbocharger in order to turn the turbocharger turbine wheel. The turbine wheel is connected to a shaft that rotates. The exhaust gases pass from the turbocharger through the following components: exhaust outlet, Diesel Oxidation Catalyst (DOC), Diesel Particulate Filter (DPF) and exhaust pipe.Turbocharger
Illustration 3 g00302786
Typical example of a cross section of a 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. 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. The rotation of the compressor wheel causes the intake air to be pressurized through the compressor housing (2) of the turbocharger.
Illustration 4 g02720975
Typical example
(12) Line (boost pressure)
(13) Wastegate actuator
(14) Actuating lever
Illustration 5 g02720981
Typical example
(15) Wastegate regulator 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. The more efficient burning of fuel 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. The diaphragm is spring loaded in the wastegate actuator which varies the amount of exhaust gas that flows into the turbine.The wastegate regulator (15) 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 wastegate regulator, that regulates the boost pressure to the wastegate actuator.When high boost pressure is needed for the engine performance, a