Audi A4

since 1994 of release

Repair and car operation

A4 Audi
+ Running gear
+ Regular servicing
+ Engines
- Turbo-supercharging
   Valve of switching off of draft
   Check of adjustment of pressure of pressurization
   The help at malfunctions
   The turbokompressor is faulty?
   Radiator of nadduvochny air
+ exhaust System
+ cooling System
+ Fuel tank and fuel pump
+ Air filter and absorption channels
+ injection System
+ Coupling
+ Transmission and main transfer
+ Suspension bracket of wheels and steering
+ Brakes
+ Wheels and tires
+ Electrotechnical equipment
+ ignition System
+ Lighting
+ Alarm equipment
+ Tools and devices
+ Heating and ventilation
+ body Details
+ Salon
Search of malfunctions
Technical characteristics


Generally the turbokompressor consists of two lopastny wheels located on one shaft. By means of one of them engine exhaust gases are removed, depending on frequency of rotation of the engine it brings a shaft into more or less fast rotation. The related second lopastny wheel, certainly, rotates together with it and soaks up air in combustion chambers, but already under pressure.

At bigger intake of air supply of gasoline for providing the correct structure of a working mix increases also.

At the left in an impellent compartment of a turbodvigatel in capacity of 110 kW you see a radiator of nadduvochny air (1) and a thick air hose (2) from a turbokompressor to a radiator of nadduvochny air.

Turbokompressor model in a cut

1–a lopastny wheel on the party of an exit of exhaust gases;
2–turbo-supercharging shaft;

3–a lopastny wheel on the absorption party;
4–vacuum box of a regulator of a turbo-supercharging.

Adjustment of pressure of pressurization

The chosen constructive data of a turbokompressor possess pleasant property to submit nadduvochny air in cylinders even at rather low turns of the engine. From this it follows that at high turns too large amount of air can be represented. Pressure in system of pressurization could rise to such level which would be harmful to durability of the engine.

Not to allow it is business of a regulator of pressure of pressurization. By valve opening it provides passing only parts of exhaust gases through a lopastny wheel of the supercharger. As a result of it the pressurization capacity decreases, and pressure cannot exceed the maximum size.

Rigid adjustment in this case is inadmissible, as in some road situations that is necessary more, it is less than air. Therefore adjustment of pressure of pressurization is influenced by the Motronic control unit. The electropneumatic valve, «the electromagnetic valve of restriction of pressure of pressurization», by means of a vacuum box operates the bypass channel of pressurization (the valve of adjustment of pressure of pressurization). When bypass the channel opens, pressure of pressurization goes down.

The height sensor is connected to the Motronic control unit (an installation site: the electronic block in an impellent compartment). Thanks to it adjustment of pressure of pressurization in a condition to level change of density of air at trips in the mountain district.

More rarefied air at the same offer of capacity ( i.e. at the same amount of injected fuel) would cause glut of a fuel and air mix. It is not allowed at the expense of a raising of pressure of pressurization and, therefore, strengthened supply of air.

Therefore engine capacity and composition of exhaust gases at a turbodvigatel remain constants under any traffic conditions.