SEMINAR ON “GASOLINE DIRECT INJECTION”

GASOLINE DIRECT INJECTION OR(GDI): 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

Components of GDI system: 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.

High Pressure lines: 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

common rail: It is a high-pressure fuel rail feeding individual injectors. 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.

INJECTORS: The solenoid-operated fuel injector 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.

FILTERS: 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.

ENGINE SENSORS: : 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

ELECTRONIC CONTROL UNIT: 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.

WORKING OF THE GDI SYSTEM Air Induction system. Fuel delivery system. Electronic control systems.

Two combustion mode 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.

Superior Output combustion: 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.

TRANSITION FROM CARBURETOR TO GASOLINE DIRECT INJECTION OPERATING DIFFICULTIES FOR A CARBURETOR ICE FORMATION BACK FIRING VAPOUR LOCK LEAKAGES LOSS OF VOLUMETRIC eff RESISTANCE TO FLOW

Advantages of GDI 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.

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