The purpose of fuel atomiser in diesel engine is to atomise or break the fuel oil into fine particles and to direct the spray into the combustion chamber so that every fuel particle mixes with the air.This purpose is some what like carburettor used in petrol engine,where petrol is break in fine particle and mixes with air.
The fuel atomiser have following important parts,
10)Spring Cap Nut
Working Of Fuel Atomiser:-
The pressure of the fuel,supplied from fuel feed pump through the fuel passages lifts the nozzle valve.The fuel passes down to the nozzle and injected into cylinder (Combustion Chamber) in the form of a very fine spray.
When the fuel pressure drops,the nozzle valve moves down under the force of the spring and rests on its seat,closing the nozzle inlet to the passage,thus the fuel supply is cut off.
Any fuel leaked past the plunger of nozzle valve is sent back to the fuel tank through return passage.The adjusting screw enables the tension in the spring,to be adjusted.Whether the valve is working properly or not can be checked with the help of feeling pin.
To obtain various types of fuel spray,there are numerous types of injection nozzles are used.
Single hole nozzle,Conical ended single hole nozzle have just one hole,through which the fuel is sprayed.In order to achieve greater penetration of the fuel spray,the multiple hole nozzles are quite useful.Somewhere long stem nozzles are also in use.The pintle nozzle,which is used in engines employing swirl or precombustion chamber,where the fuel is not required to penetrate the Air .The stem of the valve is extended to form a pintle protruding through the mouth of the nozzle body.Such nozzles are tend to give hallow conical spray varies from 40 to 60 degree,depending up on the type of the pintle.The delay nozzle is similar in action to the pintle nozzle except that the rate of fuel injection increase towards the end of the delivery.
Due to the reduce quantity of fuel sprayed in the beginning of the combustion there are reduced chances of diesel knocks.An injection nozzle should be mounted in such a manner that it is not subjected to intense heat.
The details about fuel filter will covered in next post.
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