Audi A4, S4

since 2000 of release

Repair and car operation

Turbokompressor - the general information and precautionary measures

General information

All diesel engines as well as some petrol engines, the AUDI A4 car are equipped with a turbokompressor. On a turbokompressor shaft in two separate cases two driving wheels are located. The drive of turbine wheels is carried out from the fulfilled gases. They provide rotation of a shaft of a turbokompressor and by that both turbine wheels with speed of 300 000 rpm. Greasing of a turbokompressor is carried out from system of greasing of the engine.

At the petrol engine the turbokompressor is in addition cooled with liquid.

Owing to good filling of cylinders with forced air engine capacity increases to 100 %.

Turbokompressor is intended for increase in engine capacity (to 100 %) by increase of pressure of air in the inlet pipeline. Air not simply arrives in cylinders, and moves in them under pressure. Along with capacity pressurization creates increase in a torque of the engine. Capacity growth, among other things, depends on pressure of forced air which as a rule, makes 0.4-0.8 atm. Pressure of forced air is constantly supervised and regulated by the control unit the engine. It excludes possibility of excess of pressure over the established value. According to increase in supply of air, TNVD increases supply of fuel.

The turbine of the compressor is given in rotation by the fulfilled gases. Gases, passing through a special casing (a compressor casing), move to the compressor turbine. The turbine rotates on a shaft on which other end there is a compressor wheel in a separate casing. It submits air under pressure to the pipeline.

Turbokompressor with variable geometry of the turbine (VTG) has the directing shovels which situation is regulated by the control unit the engine by means of the electromagnetic valve and a vacuum drive. It provides optimum pressure of pressurization in all range of turns that leads to higher torque and, thereby, to higher capacity, in particular, at low numbers of turns.

Between a turbokompressor and the inlet channel of the engine the air cooler (interkuler) who cools previously the air compressed by a turbokompressor is located. It increases engine capacity since cold air thanks to its higher density has higher content of oxygen.

Pressure of air in the pipeline is limited to the special sensor. At achievement of limiting pressure the sensor opens a zaslonka, limiting to that supply of the fulfilled gases to the turbine.

The shaft of the compressor is greased with impellent oil which moves on specially intended hose. The shaft constantly "floats" in oil. From the compressor oil is taken away in the pallet on a returnable hose.

In comparison with the petrol engine the diesel engine has no need to reduce extent of compression because of pressurization that provides even on low turns complete use of injected fuel.

Turbokompressor is a component of a final collector and cannot be separated from it.

Turbokompressor represents the precision mechanism. Therefore at emergence of malfunction it should be completely replaced.

Precautionary measures

Speed of rotation of turbines of the compressor is huge, and the working temperature is very great. To avoid receiving traumas, and also not to damage a turbokompressor, observe the following precautionary measures.

Do not start the engine after removal of any component of a turbokompressor. Hit of extraneous subjects on shovels of turbines can lead to an exit of the last out of operation. You also risk to be traumatized from the subjects thrown out from the turbine. After removal any a component of a turbokompressor or hoses of an air inlet cover it with pure rags. Do not give gas at once after engine start, especially if it is not heated-up. Oil cannot instantly grease a turbine shaft. Never switch off ignition at once after a car stop. Do not press an accelerator pedal before an engine stop. At once after ignition switching off oil ceases to move to a compressor shaft, and some time it will rotate without greasing. Before muffling the engine, let's to it work on single turns some minutes during which speed of rotation of the turbine considerably will decrease. Regularly change oil, the oil filter and an air purifier. Use of old oil will lead to formation of deposits on a shaft of the compressor and to its exit out of operation. Before disconnecting hoses of giving and oil return from the compressor, carefully clear nearby surfaces. The removed components store in tight containers.