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ENGINE
9
Unique CR Strategies
l Individual Injector Characterization (I2C)
l Accelerometer Pilot Control (APC)
l Cylinder balancing : Strategy to balance
engine speed difference between cylinder to
cylinder by modifying fuel delivery Cyclic
variations during flywheel rotation maintained
minimum by monitoring flywheel speed
continuously
l Anti-Oscillation Strategy (AOS): Strategy to
prevent engine speed oscillations (Derivability)
Fuel delivery is slewed based on various inputs
like rpm, pedal position, engine temperature
etc. Jerks during sudden accelerations
minimised
l Minimised individual injector spread on engine
l Minimised injector drift over lifetime
l Control of smallest pilot injection quantities
over lifetime
l Better control of multiple injection
l The accelerometer strategy is based on the
detection of the MDP (Minimum Drive Pulse)
which generates combustion
l MDP is the pulse required to inject the
smallest fuel quantity
Why APC
l Running in of Injectors - possible injector drift
l MDP changes due to physical tolerances
l Constantly update MDP to maintain same fuel
quantity over lifetime
Opearation
APC compensates possible injection quantity drift by:
l actively monitoring this drift on vehicle and
applying a compensation equal to the difference
with the nominal for every injection
Advantages
l Small pilot quantities are under control
l Enhanced diagnostic and engine protection
against fuel supply system failure.
l No vehicle dispersion for noise and emissions
l No vehicle drift during vehicle life for noise and
emissions
l Driveability in transient is improved due to a
better pressure regulation
Note:
l The pilot pulse is increased until a knock sensor
signal is detected
l Knock sensor “listens” to combustion noise from
each cylinder separately
l ECU updates MDP every 60 minutes
Precautions:
l Bleeding shouldnot bedoneby looseningHPpipes
l HPpipes are one time use only – avoidunnecessary
removal
l Do not leave inlets and outlets of CR components
exposed to dirt – Cap immediately
l Flushing of CR components should not be done
l It will introduce dirt
l Do not remove battery connectionwhen key is ON
l Do not spray water on the ECU
l Sensor connections should not be removed
unnecessarily
l HP pipes should not be bent and force should not
be applied
l Fallenor brokenCRcomponents shouldnot beused
l Avoid entering Test bed while engine is running at
high speed and high load as any high pressure
leakagemay cause injury
l Monitor battery voltage continuously - recharge
battery if voltage drops below10Volts
l I2C values must be entered correctly according
to cylinder order
l Drainwaterfromfilterandsedimenteratregularintervals
Individual Injectors Characterisation (I 2 C)
Manufacturing tolerances of injector components:
l Scattering of fuel delivery and opening delay
from injector to injector
l I2C (16 digit code) for correcting the fuel
delivery and opening delay
l Exact defined injection quantity
l Equals injection quantity from injector to injector
l Important to achieve future emission legislation levels
l Manufacturing process control
Precaution
I2C values must be fed in correct cylinder order.Wrong
entry will lead to unwanted engine vibrations and noise
Accelerometer Pilot Control strategy (APC)
What is Accelerometer
l Accelerometer is a Knock Sensor which listens
to Combustion knock