Yaroslavl Engine Plant YMZ-536 Operation Manual page 91

three sections each of which is fed through a dosage device with an
electric valve. The HP pump sends the fuel under pressure to the
common fuel accumulator (rail) 9 from where the fuel is delivered to
each injector via an individual line. The injectors deliver the fuel
under pressure into the combustion chamber. Injection duration is
determined by the duration of the electric pulse from the ECU.
The fuel pressure in the common rail optimal for the given
engine operation mode is set by the ECU and determined by the
balance of the flow rate of fuel through the injectors and the fuel
pump capacity.
In the Common Rail system the fuel injection pressure does not
depend on the injection start and duration. Due to this fact, alongside
with the main injection which determines the diesel engine torque,
other injection stages can be implemented:
 pilot injection of a small amount of fuel aimed mainly at
reducing combustion noise;
 post-injection to reduce exhaust emissions.
The actual amount of injected fuel depends on the injection
pressure and duration.
The sensors mounted on the engine send the information on the
operation of different systems to the ECU. The ECU uses this
information to control injection and send the signals related to the
operation of other systems to the dashboard as well as to control other
actuators ensuring the engine operation.
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