Audi 80/Avant (B4)
Since 1991-1995 of release
Repair and car operation
+ The description
+ System of release of the fulfilled gases
+ Cooling system
+ Fuel tank and the fuel pump
+ The air filter and воздухозаборные channels
+ Injection system
+ Transmission and transmission
+ Suspension bracket and steering
+ Brake system
+ Antiblocking system of brakes
+ Wheels and tyres
+ Kuzovnaja electrosystem
- Ignition system
Various systems of ignition
Principle of work of ignition
Impulses for the management block
Regulation on a detonation
Security measures at work with ignition system
Repair of system of ignition
Diagnostics of system of ignition
The ignition distributor
The gauge of detonation combustion
High voltage elements
Replacement of spark plugs
Check of the moment of ignition
+ Signalling devices
+ Devices and auxiliary devices
+ Heating and ventilation
+ Body elements
+ Search of malfunctions
The ignition system provides correct passage of process of combustion to the engine thanks to purposefully "shot" igniting sparks. And all occurs precisely because at averages of the engine of 3000 rpm each cylinder needs 25 sparks in a second. So 100 sparks in a second, 6000 in a minute, 360 000 at an o'clock and so on is required to the 4-cylinder engine.
That ignition can
That in a spark plug in the combustion chamber the spark in general could slip, between spark plug electrodes there should be a pressure a minimum 30 000 V.Akkumuljatornaja the battery gives, however, only 12 In pressure. Thus, pressure of the accumulator needs to be raised repeatedly. Duration of flash not the tenth, and not the 100-th, but thousand fractions of a second. It is necessary to it to work a bit earlier or later, and efficiency of ignition, and thereby and capacity of the engine will be lowered.
When there is an ignition?
The spark should slip precisely in the fullness of time. However to establish, when there will be this most necessary moment, not so is simple.
ВМТ and an ignition advancing
With increase of turns of the engine the igniting spark should jump over all earlier as – we already mentioned it in last section – the fuel and air mix needs constantly same time to ignite. Only thus combustion occurs in the fullness of time namely when the piston only begins movement downwards.
Combustion of a mix of fuel and air depends, however, and on its structure. If the accelerator pedal is squeezed out very little («partial loading»), ability of a mix in combustion chambers to ignition decreases: therefore it burns down more slowly and for this reason should ignite earlier.
In other situations it is necessary, that the ignition moment moved towards late ignition. Ignition in that case occurs only when the piston passed for a long time already ВМТ. Thus, ignition occurs practically in a release step that improves structure of the fulfilled gases, but worsens capacity of the engine. According to the aforesaid, later ignition is is unique correct, for example, at engine work in a mode of compulsory idling (for example, at movement under a hill with the released pedal of an accelerator).