SNS COLLEGE OF ENGINEERING Coimbatore-107 Subject: Thermal Engineering Fuel injection systems BY SIVAKUMAR P AP/MECH

An indirect injection system sprays fuel into the engine  intake  manifold.   Most  gasoline  injection systems are of this type. Direct injection forces fuel into the engine combustion chambers. Diesel injection systems are direct type.

WHY EFI ? Strict emission standards require precise fuel delivery ECU used to calculate fuel needs EFI very precise, reliable & cost effective EFI provide correct A/F ratio for all loads, speeds and temperature ranges

BASIC FUNCTION OF EFI The process of determining the amount of fuel, and its delivery into the engine, are known as fuel metering An electronic engine control unit calculates the mass of fuel to be injected The fuel injector acts as the fuel-dispensing nozzle. It injects liquid fuel directly into the engine's air stream

EFI COMPONENTS Injectors Fuel Pump Fuel Pressure Regulator ECM - Engine Control Module; includes a digital computer and circuitry to communicate with sensors and control outputs Wiring Harness Various Sensors: Crank/Cam Position sensor MAF sensor/ MAP sensor Oxygen sensor

W h a t i s M P F I ? It is an electronically controlled injection system in which there is one injector per cylinder placed in the inlet manifold. It facilitates effective air-fuel ratio for all dynamically varying conditions so that pollution comes down.

MULTI POINT FUEL INJECTION

INJECTOR

COMMON RAIL DIRECT INJECTION Direct fuel injection evenly distributes fuel throughout the system, from injector to injector. Pressure generation is decoupled from and independent of engine speed. The direct injection system can be programmed for optimal performance over the entire engine speed range.

THE CRDI DIFFERENCE In conventional engines, the amount of fuel injected rarely changed in accordance with the demands of the driver. However, the CRDI engine achieved the set goals by isolating the two functions — generating pressure and maintaining a real-time check on the amount of fuel injected. Diesel is stored in the common rail at a constant pressure ranging from about 1,600 bar for passenger cars and 1,800 bar for commercial vehicles. Because of the high pressure injection, the fuel gets atomized finely and quickly which reduces the physical delay associated with the combustion process.

How direct injection works Utilizes a lightweight, compact solenoid requiring less energy to motivate. Fast solenoid speed permits fine metering of pilot and main injection. Capability of pressure up to 1600 bar. Feedback system analyzes the quality of combustion and permits the adjustment of the fuel system.

Fuel Rail

GASOLINE DIRECT INJECTION

GASOLINE DIRECT INJECTION First - 1902 - French - Aircraft First - 1952 - Automobile - Bosch - used in Mercedes-Benz 300SL sports car - in cylinder block. 1996 - GDI reappeared in Mitsubishi - the first Japanese car In 2000 VW Lupo - Fuel Stratified Injection (FSI) and Turbo Stratified injection (TFSI) Fuel injected directly into the combustion chamber This allows engine to operate in two modes, viz. Homogeneous mode (Early Injection) - During suction stroke Stratified mode (Late Injection) - During compression stroke Combines the advantages of petrol engine and diesel engine

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