The turbocompressor fastens flanges to a final collector and inlet system.
Fig. 4.75. A turbocompressor in coal mine (290TD): 1 – turbine; 2 – shaft; 3 – oil channel; 4 – compressor
The case of a turbocompressor is divided into two compartments: turbine 1 (fig. 4.75) and compressor 4. Is in everyone on a krylchatka. They rigidly sit on one shaft 2. The turbine is set in motion by a stream of the fulfilled gases, the compressor forces the air coming via the case of the valve of management of pressure to cylinders.
The regulator of pressure of the forced air
Both krylchatka of the turbine can reach very big turns, more than 100 000 min.-1. At the same time pressure of the forced air can rise higher than 2 bars. As such pressure is superfluous, on the compressor the air pressure regulator performing pressure decline function is installed.
When turns of the turbine reach about 50 000 min.-1 and small pressure is created, the regulator works so that pressure even on small turns remained constantly that helps to avoid "failures" at sharp increase in turns.
If pressure on the regulator at big loadings rises above set (0,9 bars), the membrane opens. At the same time only a small part of the fulfilled gases will work for the turbine, and other part will go to the muffler.
For maintenance of necessary pressure of the forced air at the movement at any heights (in mountains) the increases sensor is built in the control unit. At the movement in the rarefied air the sensor sends a signal to increase in pressure of the compressor and by that keeps normal mixture of air with fuel.
Fig. 4.76. VTG turbocompressor in a section: 1 – krylchatka of the turbine; 2 – the exposed directing shovels; 3 – adjusting wheel of shovels; 4 – draft with the adjusting lever; 5 – krylchatka of the compressor; 6 – vacuum chamber
4-cylinder engines with the Common Rail system are equipped with so-called VTG turbocompressors with changeable geometry of turbines (fig. 4.76).
In the VTG compressor the section of a stream of air changes depending on power setting, thanks to it optimum pressure is forced. Optimum pressure is reached by means of the control unit, depending on characteristics of installation of the directing turbine shovels in the compressor.
At small turns of the engine of a shovel are covered, reducing air stream section, and pressure increases; at big turns section increases and pressure falls.
It reaches a number of advantages:
1. Change of installation of the directing shovels allows to use optimum energy of the fulfilled gases and to reach high efficiency owing to a wide choice of characteristics of management.
2. Increase in pressure of the forced air on low turns. The turbocompressor works quicker, thereby excepting "failures" upon transition from low turns to high.
3. Increase in torque owing to the best filling of cylinders.
4. Reduction of smoking at full loadings owing to existence of a reserve of the forced air.
5. The improved dynamics of pressure of forcing.
6. Refusal of the valve of adjustment of pressure of the forced air (waste gate).
7. The increased power owing to the elevated pressure of forcing at small turns, therefore — optimum regulation of forcing.
1. If the turbocompressor does not work, it can be a consequence of bystry switching off of the hot engine at once after the long movement on the maximum turns. At such mode there can be a coking up of the compressor: shaft bearings, especially from the turbine of the fulfilled gases, strongly overheat, in them burns out oil, and they can stick. If it often repeats, bearings will become useless and they should be changed. Therefore never right after the long movement at the maximum loads you suppress the engine, let's it still some time work on single turns.
2. Never start the engine without air filter, small firm particles can damage the compressor (speed of rotation of the turbine on perimeter — to 500 m / c). Before changing the compressor, it is necessary to check functioning of the following knots (according to a cause of defect): ignition, a power supply system, a compression, the air filter and tightness of connections of system of forcing of air and system of production of the fulfilled gases.
Radiator of cooling of the forced air
The air cooling radiator located between a turbocompressor and the case of the valve of adjustment of pressure is connected to a contour of cooling of the engine. If air in the compressor reaches temperature of +110 °C, then, passing through a radiator, it is cooled to +70 °C.
In the mixing camera located behind a radiator clean air mixes up with the fulfilled gases in the proportion calculated by means of the computer that power setting was optimum. For this purpose the mixing camera is equipped with the special valve of removal of the fulfilled gases and the throttle valve which is run by the electric air converter. Drosselirovaniye of air increases pressure difference between the forced air and the fulfilled gases and thus influences productivity of system of removal of the fulfilled gases.
Fig. 4.77. The direction of a stream of air (it is shown by shooters): 1 – turbocompressor; 2 – branch pipes; 3 – radiator
Cleaning of a radiator of cooling of the forced air
SEQUENCE OF WORKS
"30 000 km"
You make cleaning of a radiator of cooling of naduvochny air during the summer period of operation of the car. This operation is made as well as with a cooling system radiator.