10.8.2. Work of system of injection of fuel
The amount of the fuel submitted by nozzles, is regulated by an electric pulse signal from EBU. It traces data on an engine condition, counts need for fuel and determines necessary duration of supply of fuel by nozzles (duration of an impulse – porosity). For increase in amount of submitted EBU fuel increases duration of an impulse, and for reduction of supply of fuel – reduces.
EBU possesses ability to estimate results of the calculations and teams, to remember modes of recent work and to operate 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 shutdown of a food of EBU.
Fuel moves on one of two different methods: synchronous, i.e. at the certain provision of a cranked shaft, or asynchronous, i.e. it is independent or without synchronization with rotation of a cranked shaft. Synchronous injection of fuel – most often applied method. Asynchronous injection of fuel is applied generally in a mode of start-up of the engine. EBU includes nozzles consistently. Each of nozzles joins through everyone 720 ° turn of a cranked shaft. Such method allows to dose out more precisely fuel on cylinders and to lower level of toxicity of the fulfilled gases.
The amount of submitted fuel is defined by an engine condition, i.e. a mode of its work. These modes are provided with EBU and are described below.
When the cranked shaft of the engine starts to be scrolled by a starter, the first impulse from the sensor of provision of a cranked shaft causes an impulse from EBU on inclusion at once all nozzles that allows to accelerate engine start-up.
Initial injection of fuel occurs each time at engine start-up. 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 heated-up – duration of an impulse decreases. After initial injection of EBU it 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 cranked shaft of the engine starts to be turned, EBU forms the phased impulse of inclusion of the 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 submitted fuel), and on heated-up – it is less.
Enrichment mode at acceleration. EBU watches 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 at the expense of increase in duration of an impulse of injection. The enrichment mode at acceleration is applied only to management toplivopodachy in transitional conditions (when moving butterfly valve).
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 disconnect completely for the short periods of time impulses of injection of fuel. Shutdown and inclusion of supply of fuel in this mode occurs at creation of certain conditions on temperature of cooling liquid, frequency of rotation of a cranked shaft, speed of the car and a corner of opening of a butterfly valve.
Supply voltage compensation. At power failure the system of ignition can give a weak spark, and the mechanical movement "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 storage battery (or tension in an onboard network of the car) EBU reduces time of accumulation of energy in coils of ignition and duration of injection.
Mode of shutdown of supply of fuel. At an engine stop (the switched-off ignition) fuel a nozzle does not move, owing to what spontaneous ignition of a mix in the peregrety 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 cranked shaft, i.e. it means that the engine does not work.
Shutdown of supply of fuel occurs and at excess of maximum permissible frequency of rotation of a cranked shaft of the engine for protection of the engine against work on is inadmissible high turns.