5.2.10. ECU
ECU estimates the signals received from external sensors and limits them to the admissible level of tension.
On the basis of the entrance data and characteristics which are written down in memory of the microprocessor, ECU calculates time and the moment of injection of fuel and transforms these parameters to output signals which are used for management of fuel nozzles. Besides, output signals are also used for management of various elements and systems, such as the drive of system of recirculation of the fulfilled gases, management of the relay of the fuel pump, fan of a radiator, preliminary heating of the engine and air conditioning system. Executive mechanisms are protected from short circuit and break of an electric chain, at the same time any damages register in memory of the microprocessor. Many output signals are used in other systems of the car.
The greatest loading for the weekend ECU cascades render fuel nozzles. Current of the output cascade creates in the solenoidal valve of a nozzle magnetic field which is put to a part of a nozzle with the fuel which is under high pressure. For ensuring exact amount of injectable fuel opening of a nozzle has to happen very quickly that demands giving of ECU of high voltage. The chain of management of a fuel nozzle has two phases: the opening phase which is characterized by consumption of big current and the deduction phase which is characterized by consumption of small current.
ECU meets the high requirements relatively:
– influences of surrounding temperature within –40... +85 °C;
– resistance to influence of fuel and lubricants;
– resistance to moisture influence;
– mechanical loadings.
ECU also has electromagnetic compatibility (EMC) and has the low level of the radiated hindrances.