Fuel Delivery System in Diesel Powered Automobiles

The operation of fuel delivery system in diesel engine is different from that of a petrol engine. In diesel engine, fuel is added at end of the compression stroke and fuel is not mixed with air. The type of ignition in diesel engine is a compression ignition system which ignites the fuel by increasing the pressure of the fuel.

*Components of a diesel fuel delivery system

*Fuel tank: It is a temporary storage component for the diesel fuel.

*Low pressure pump: Diesel is pumped to the fuel injection pump at low pressure by using a low pressure pump.

*Filter: A fuel filter aids in the removal of any impurities that may present be in the fuel.

*Fuel injection pump: Fuel injection pump is the most important part of the delivery system. It creates required amount of pressure in the diesel.

*Fuel injectors: Fuel injectors help to inject the fuel into the engine's cylinder.

*Working of fuel delivery system in diesel engine

*Diesel is pumped from the fuel tank by a low pressure pump. The pumped fuel is passed through the filter which helps to remove impurities that may be present in the fuel.

*Diesel after filtration is supplied to the inlet port of fuel injection pump. Diesel is pressurized to required level and fed into the fuel injector.

*The fuel injectors forces the diesel into the cylinder at the end of the compression stroke, for every cycle of engine operation.

*Fuel injection pump in the diesel engine is operated by means of a cam shaft.

*Advanced fuel delivery system in diesel engines: Common Rail Direct Injection (CRDI)

*Working of CRDI

*Fuel is injected directly into the cylinders of engine by a single common line known as common rail which connects all the fuel injectors.

*In ordinary diesel injection system, pressure is built for each and every cycle of injection. But in CRDI, engines maintain constant pressure for the entire fuel line regardless of the injection sequence.

*Pressure is maintained constant by electronic control unit (ECU) depending on the need and the data obtained from sensors on crankshaft and camshaft.

*In CRDI, injection and compression are independent of each other, this enables fuel to be injected as required, thus saving fuel and limiting emissions.

*Benefits of CRDI

*CRDI helps to maintain the diesel at constantly high pressure around 1800 bars. With this high pressure, diesel is split into minute particles and is thoroughly atomized. This enables an increased performance and power in the automobile.

*CRDI also restricts the exhaust vapors thus reducing the pollution caused by the automobiles. There is a uniform mixing of air and diesel, so un-burnt fuel is less, leading to less pollution.

*Ordinary diesel engines produce high noise, whereas CRDI engine produces very less noise.

*The common rail in CRDI is pressurized by the fuel pump and the CRDI is independent of cam shaft operations.

Fuel delivery system in diesel engine offers better fuel efficiency. The amount of fuel burnt in a single cycle is optimum and the wastage is less.