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ENGINE
6
Knock Control:
A sensor mounted on the engine detects when the
knock occurs and allows the ECU to determine on
which cylinder knock is occurred. Then the Ignition
and fuelling corrections are applied to prevent further
knock and thus protecting the engine from any
damages. Further an intelligent software strategy
enables a ‘Cylinder selective’ knock control, despite
the ignition is ‘grouped’.
Gear Ratio Determination:
Employing different calibrations for open loop Idle
control and fuel cut off depending on which gear is
currently selected can enhance Drivability. Gear
ratio, and hence the gear engaged, is calculated
from the vehicle’s measured engine speed and road
speed. This input is further synchronized with the
‘Anti- surge’ functions for a smoother drivability
during the transients (accelerations and
decelerations).
Purge Control:
Fuel vapours generated in the fuel tank is stopped in
a canister, in order to limit the hydrocarbon
emissions into the atmosphere. The vapours stored
in the canister are purged into the engine under
controlled conditions via a Purge valve to minimize
any detrimental effects on drivability or on the
emissions. Irrespective of the mode of fuel, the purge
control mechanism vents the fuel vapours to limit the
evaporative emissions.
Engine Speed Limiting:
Engine speed is limited through ECU. The cut off is
introduced progressively to make the operation
smooth to the driver.
Vehicle Speed Limiting:
The vehicle speed is limited from over speeding to
provide safety and protection. A smooth vehicle
speed cut off is applied in order to have a better
drive ability feel.
Gear
Position
Speed
Limit in
Petrol
Mode
(kmph)
Speed Limit in CNG
Mode (kmph)
Petrol
above
low
fuel level
in Petrol
Tank
Petrol
below
low
fuel level
in Petrol
Tank
1st
35
35
30
2nd
60
60
55
3rd
90
90
75
4th
105
105
105
Auxiliary load Input Information:
Auxiliary drive like power steering, Air-conditioning
and Alternator load information are taken into
consideration in order to have a better idle speed
control and the drive ability.
CNG EMS OVERVIEW:
Tata MPFI Bi-fuel CNG BS IV uses the most
advanced Gas Injection System. ECU controls the
operations in gasoline as well as CNG.
CNG SENSORS AND ACTUATORS
The EMS for CNG injection has the following EMS
components in addition to the standard Petrol EMS
components.
CNG injectors.
Pressure And Temperature (P&T) Sensor on
CNG rail
Safety Shut-Off (Solenoid) Valve on CNG
tank.
Safety Shut-Off Valve (Solenoid) on pressure
regulator.
Fuel Selector Switch (FSS)
Tank pressure sensor in pressure regulator
The CNG system other than the EMS components
has the following mechanical components
CNG tank / Cylinder
Pressure Regulator with tank pressure sensor
CNG L.P.Filter
CNG Rail with P & T sensor.
CNG L.P. lines.
CNG H.P. lines.