Fuel Injection System In Diesel Engine

Sukhpreet Singh Jhajj

Mechanical Engg.Group 2Semester -7th

What is a Pump?

Pump is the know as the heart of the engine.

It is used in all the diesel vehicles.

Its work is to suck fuel from the tank and supply it to the engine cylinder for Combustion with high pressure.

Need of Pump

Both engines convert fuel into energy via a series of minor explosions or combustions. However, the way the combustion happens is different in both engines. In gasoline engine, the air is mixed with fuel and the combined substance gets compressed by pistons. The explosion is ignited by a spark. On the other hand, in a diesel engine, air is compressed first which causes the air to heat up. Then the fuel is injected, which ignites the explosion.

Who developed this?

It was developed by Sir Robert Bosch in Germany during the late 1927.

Types of Pump

Inline or Multi-cylinder Pump

Single cylinder Pump

Distributor or Rotor Pump

Common Rail System

Inline Fuel Injection PumpTechnical

characteristicsThe in-line fuel-injection

pump is lubricated by the engine oil circuit, it can also cope with lower fuel grades. Long-lasting reliability and durability are only guaranteed if regular maintenance is carried out.

Pressure given by this pump is 550 bar

OperationThe cylinders are

arranged in a row. Each individual cylinder is supplied with fuel by its own plunger-and-barrel assembly via a pressure valve. The engine drives the pump's camshaft via cogs or a chain. The pump runs half as fast as the engine – synchronously to the piston movements.

Working Principal When the vehicle starts the

pump sucks the fuel from the fuel tank. With the help of feed pump.

The fuel is filtered with the help of fuel filter.

Then it goes inside the pump. Then the work of the barrel

and plunger starts by the timing of the firing order they create the high pressure and gives out through injectors to the nozzles. The extra fuel left in the nozzle is returned back to pump by returning valve.

Inline Pump

Inline PumpAdvantages:-Easy to repair as each

of the cylinder have its own barrel so easy to find the fault.

Caters to requirment of 2-12 cylinder with 25hp to 540hp output.

Speed range upto 3500rpm

Disadvantages:-Exhaust too high.Low pressure.Meets upto Euro 3

Emission only.

Distributor Pump or Rotor Pump

It was also developed by BOSCH.It was designed because inline pump was

bulky and its size was too big.It is the compact pump it generates even

more pressure than the inline pump.The pressure is near about 950bar.It has a mechanical governor to maintain the

fuel supply

Distributor Pump Technical

CharacteristicThe Distributor Pump is

lubricated by the Fuel. It cannot cope with lower grade fuel. It is durable and has a high life than the inline pump.

Operation It is a single pump it

don’t have barrel for each of the injectors.

Only one pump with the help of camplate the firing order is maintained.

Working Principle The fuel is sucked into the

pump with the help of vane pump present inside the pump.

The fuel is also used for lubrication inside the pump because it don’t allow the lubrication oil to come inside that.

One distributor head is used to supply the fuel to the injectors according to the timing set by the cam plate.

Mechanical governer is used during the fluctuation of speed to maintain fuel supply

Distributor Pump

Distributor PumpAdvantages :-Designed to achieve

low exhaust emission.Compact and light

weight.Easy adaptability to

variety of engine requirement.

Speed range upto 5000rpm.

Disadvantages :-High care is required as

it uses diesel as a lubrication if the lubricating oil enters the pump or the water enters inside the pump it gets damaged.

Common Rail System

It is the new technology used now a days.It generates high pressure than all the pump

made till now.Pressure is near about 1450bar.It functions with the help of ECU.It was first introduced for the light vehicles.Now a days it is also used in heavy vehicles.

Working Principle

The fuel is first sucked form the fuel tank the comes to the fuel filter. The it comes to a high pressure pump which pressurise the fuel upto

1450 bar. High pressure pump has 3 pistons or plunger inside this which is used

to increase pressure. It don’t have any governor all the speed and fuel supply is

maintained by the ECU. Then the fuel is send to the common rail or the pipe which maintains

the pressure at the same level as given out by the pump. Then by the ECU according to the firing order it is released out from

the pipe to the injectors.

Common Rail System

Common Rail SystemAdvantages:-High pressure.Constant pressure.No mechanical power

needed.Accuracy more.

Disadvantages:-ECU damaged it stops

working.Not water resistant.No repairment of

common rail.

Conventional Common rail

Fuel metering Mechanical governor

Injection timing control

Mechanical timer

Fuel pressure build up

Pump

Fuel distribution Pump

Injection pressure control

Depend on engine speed

Fuel metering Engine ECU, injector

Injection timing control

Engine ECU, injector

Fuel pressure build up

High Pressure Pump, ECU

Fuel distribution Engine ECU, Rail

Injection pressure control

Engine ECU, Metering Valve

Comparison between Conventional vs. Common rail

THANK YOU