Gasoline direct injection: GDI is a variant of
fuel injection employed in modern four stroke
petrol engines. The gasoline or petrol is highly
pressurized, and injected via a common rail fuel
line directly into the combustion chamber of each
cylinder
Fuel pump: fuel injected engines often use
electric fuel pumps that are mounted inside the
fuel tank. And some fuel injected engines have
two fuel pumps: one low pressure/high volume
supply pump in the tank and one high
pressure/low volume pump on or near the engine.
This tube or pipe connects pump to the
common rail. The pipe assembly transports fuel
at high pressure between pump, rail and injectors,
remains completely sealed and resistant to
pressure changes
It features a high-pressure (over 1,000 psi) fuel
rail feeding individual injectors.
In common rail systems a high pressure pump
stores a reservoir of fuel at high pressure.
It consists of a valve body and needle valve to
which the solenoid plunger is rigidly attached.
The needle valve is pressed
against a seat in the valve
body by a helical spring
to keep it closed until
the solenoid winding
is energized.
One of the most important system components is
the fuel filter which acts as the engine’s first line
of defence.
prevent large particle
entering engine.
Large particles in the
fuel also have the ability
to clog fuel injectors.
: In order to provide the correct amount of fuel for
every operating condition, the engine control unit
(ECU) has to monitor a huge number of input
sensors.
mass air flow sensor.
oxygen sensor
throttle position sensor
coolant temperature sensor
engine speed sensor
Manifold absolute pressure sensor
Crank angle sensor
Voltage sensor
This unit is the heart of electronic injection
system which is responsible for metering the
quantity of fuel supplied to each cylinder.
The ECU determines precisely how much fuel
needs to be delivered by the injector by
monitoring the engine sensors.
The ECU turns the injectors on for a precise
amount of time, referred to as injection pulse
width.
Air Induction system.
Fuel delivery system.
Electronic control systems.
Ultra-Lean combustion:
optimally stratified air-fuel mixture immediately
beneath the spark plug.
This mode thus facilitates
lean combustion and a
level of fuel efficiency.
The GDI engine switches automatically to
Superior Output Mode when the driver
accelerates, indicating a need for greater power.
fuel is injected during the
intake stroke, when the piston
is descending towards the bottom
of the cylinder, vaporizing
into the air flow and following
the piston down.
OPERATING DIFFICULTIES FOR A CARBURETOR
ICE FORMATION
BACK FIRING
VAPOUR LOCK
LEAKAGES
LOSS OF VOLUMETRIC eff
RESISTANCE TO FLOW
Increased fuel efficiency and high power
output.
Does no require choke.
With fuel injection, fuel mixture requires no
extra heating during warm up.
Delivers a more evenly distributed mixture of
air and fuel to each of the engine's cylinders,
which improves power and performance.