 printable version
Turbocharger
Turbocharger flanges attached to the exhaust manifold and the intake system.
| Fig. 4.75. Turbocharger sectional (290TD): 1 - turbine; 2 - shaft; 3 - oil passage; 4 - Compressor
|
Turbocharger casing divided into two compartments: one turbine (fig. 4.75) and the compressor 4. Each impeller is located. They sit firmly on a shaft 2. The turbine is driven by the exhaust gas flow, the compressor pumps air flowing through the valve body controlling the pressure in the cylinders. Charge air pressure regulator Both the turbine impeller can reach very high rpm, more than 100 000 min -1. The pressure of forced air can rise above 2 bar. Since such pressure excessively, the compressor installed air pressure regulator that performs the function of reducing the pressure. When the turbine speed reaches about 50 000 min -1 and creates a slight pressure, the controller works in such a way that the pressure even at low engine speeds is kept constant, which helps to avoid "failures" with a sharp increase in turns. If the pressure regulator at high load rises above a predetermined (0.9 bar) and opens the membrane. However, only a small part of the exhaust gas to the turbine will operate, and the rest will go to the muffler. To maintain the required boost pressure when driving at all altitudes (in the mountains) in the control unit is integrated sensor "increase." When moving in the rarefied air sensor sends a signal to raise the pressure of the compressor and thereby maintains normal mixing air with the fuel. VTG-turbocharger
| Fig. 4.76. VTG turbocharger in a cut: 1 - impeller of the turbine; 2 - exhibited guide vanes; 3 - mounting the wheel blades; 4 - draft of a mounting lever; 5 - the impeller compressor; 6 - vacuum chamber
|
4-cylinder engines with Common Rail equipped with so-called VTG-turbochargers with variable turbine geometry (Fig. 4.76). The VTG-compressor section air flow varies depending on the engine operating condition, it is pumped through the optimal pressure. The optimum pressure is achieved by the control unit, depending on the installation characteristics of the turbine guide vanes within the compressor. At low engine speeds vanes are covered, reducing the air flow section, and the pressure increases; at high speeds-section increases and the pressure drops. This achieves a number of advantages: 1. Shift the installation guide vanes makes optimum use of the energy of the exhaust gas and to achieve a high efficiency due to the large choice of performance management. 2. Increasing boost pressure at low engine speeds. The turbocharger is faster, thereby eliminating the "gaps" in the transition from low speed to high speed. 3. Increased torque due to better filling of the cylinders. 4. Reduce fuming at full load due to the presence of forced air reserve. 6. Failure to control valve boost pressure (waste gate). 7. Increased capacity due to increased injection pressure at low engine speeds, thus - optimal regulation of injection.
PRACTICAL ADVICE 1. If the turbocharger is not working, it may be a consequence of the rapid shutdown of the hot engine immediately after a long movement at maximum speed. Under such a regime can occur coking compressor shaft bearings, especially on the part of the turbine exhaust gas, overheated, they burn oil, and they can become attached. If this occurs frequently, the bearings will be ruined and they have to change. Therefore, never once after a long movement at maximum loads do not stop the engine, give him some time to idle. 2. Never run the engine without an air filter, fine solid particles can damage the compressor (turbine speed on the perimeter - up to 500 m / c). Before changing the compressor, it is necessary to check the operation of the following components (or cause of the problem): ignition, fuel supply system, compression, air filter and the tightness of the air injection system and exhaust system. |
Radiator cooling air discharge Radiator cooling air disposed between the turbocharger and the pressure control valve body is connected to the cooling circuit of the engine. If the air in the compressor reaches a temperature of +110 ?� C, then passes through the radiator, it is cooled to +70 ?� C. The heat sink located behind the mixing chamber is mixed with fresh air in the exhaust gases calculated by computer proportion to engine operation to be optimal. To do this, the mixing chamber is equipped with a special valve exhaust system, and throttle valve, which is controlled by an electro-pneumatic transducer. Throttling air increases the pressure difference between the injected air and the exhaust gases and thus affects the performance of the exhaust system.
| Fig. 4.77. Air flow direction (indicated by arrows): 1 - the turbocharger; 2 - fittings; 3 - radiator
|
Cleaning charge air cooler
"30,000 km" Purification of the charge air cooler make in the summer operation of the vehicle. This operation is performed in the same way as with the radiator of the cooling system.
| 
