Nozzles are precision parts of the diesel engine, it is easy to produce the fault are: a tapered surface of the needle valve body tapered needle wear , needle and needle guide hole surface wear , extend the injection hole , the needle stuck the spray hole blocking , the injection pressure is too high or too low .
The following outlines the development trend of diesel fuel injector nozzles, Diesel injector is one of precision parts , with the gap between the needle and the needle valve body is only 0.002 ~ 0.003 mm. The shape of the fuel system injector is a very important parameter , its spray quality , injection form, the state of the fuel and air mixture has a great influence these factors directly affect the engine's emission targets. To meet the increasingly stringent diesel emission requirements , access to better economic performance and emissions performance , Nozzles appeared the following trends:
( 1 ) Increasing the injection pressure, especially at low speed condition ;
( 2 ) Increasing the number of nozzle orifice , reducing the nozzle diameter ;
( 3 ) A variable fuel injection rate , as the pre-injection and the like.
Injector is the role of a certain pressure atomization of diesel oil into small uniform grain, to make diesel nicely mixed with air in the combustion chamber. Structural parameters of injector nozzle holes, diameter, cone angle, which is located at the top of the combustion chamber, direct exposure to high temperature and pressure combustible gas mixture, operating temperature, and poor working conditions. Thermal and mechanical loads needle Couples often cause poor sealing, gas back channeling, or even stop working, in addition, good or bad injector working conditions directly affect the economy of the diesel engine, power, emissions and reliability.
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