10.8.2. Work of system of injection of fuel
The amount of the fuel given by nozzles is regulated by an electric pulse signal from EBU. He traces data on a condition of the engine, counts the need for fuel and determines the necessary duration of supply of fuel by nozzles (impulse duration – porosity). For increase in amount of the given EBU fuel increases impulse duration, and for fuel supply reduction – reduces.
EBU has ability to estimate results of the calculations and teams, to remember the modes of recent work and to work according to them. "Self-training" or adaptation of EBU is continuous process, but the corresponding settings remain in random access memory of the electronic block and respectively before the first power off of EBU.
Fuel moves by one of two different methods: synchronous, i.e. at a certain provision of a bent shaft, or asynchronous, i.e. it is independent or without synchronization with rotation of a bent shaft. Synchronous injection of fuel – the most often applied method. The asynchronous injection of fuel is applied generally in the mode of launch of the engine. EBU includes nozzles consistently. Each of nozzles joins through everyone 720 ° turn of a bent shaft. Such method allows to dose more precisely fuel on cylinders and to lower the level of toxicity of the fulfilled gases.
The amount of the given fuel is defined by a condition of the engine, i.e. the mode of its work. These modes are provided to EBU and are described below.
When the bent shaft of the engine begins to be scrolled by a starter, the first impulse from the sensor of provision of a bent shaft causes an impulse from EBU on inclusion of all nozzles at once that allows to accelerate launch of the engine.
The initial injection of fuel happens every time at launch of the engine. Duration of an impulse of injection depends on temperature. On the cold engine the impulse of injection increases for increase in amount of fuel, on warmed up – duration of an impulse decreases. After initial injection of EBU is switched to the corresponding control mode by nozzles.
Start-up mode. At inclusion of ignition of EBU turns on the relay of an electrogasoline pump which creates pressure in the highway of supply of fuel to a fuel stage.
EBU checks a signal from the sensor of temperature of cooling liquid and defines amount of fuel, necessary for start-up, and air.
When the bent shaft of the engine begins to be turned, EBU forms the phased impulse of inclusion of nozzles which duration depends on signals of the sensor of temperature of cooling liquid. On the cold engine duration of an impulse is more (for increase in amount of the given fuel), and on warmed up – it is less.
The enrichment mode at acceleration. EBU monitors sharp changes of provision of a butterfly valve (on a signal of the sensor of provision of a butterfly valve), and also behind a signal of the sensor of a mass consumption of air and provides giving of additional amount of fuel due to increase in duration of an impulse of injection. The enrichment mode at acceleration is applied only to management of fuel feeding in transitional conditions (when moving a butterfly valve).
The mode of shutdown of supply of fuel when braking by the engine. When braking by the engine with the included transfer and coupling of EBU can for the short periods of time completely disconnect fuel injection impulses. Shutdown and inclusion of supply of fuel in this mode happens during creation of certain conditions on temperature of cooling liquid, frequency of rotation of a bent shaft, speed of the car and the angle of opening of a butterfly valve.
Compensation of supply voltage. At power failure the system of ignition can give a weak spark, and mechanical motion of "opening" of a nozzle can take more time. EBU compensates it by increase in time of accumulation of energy in coils of ignition and duration of an impulse of injection.
Respectively at increase in tension of the rechargeable battery (or tension in onboard network of the car) EBU reduces time of accumulation of energy in coils of ignition and injection duration.
Fuel supply shutdown mode. At an engine stop (the switched-off ignition) fuel a nozzle does not move owing to what spontaneous ignition of mix in the superheated engine is excluded. Besides, impulses on opening of nozzles do not move in case EBU does not receive basic impulses from the sensor of provision of a bent shaft, i.e. it means that the engine does not work.
Shutdown of supply of fuel happens also at excess of maximum permissible frequency of rotation of a bent shaft of the engine for protection of the engine against work on unacceptably high turns.