The nozzle is the main actuation mechanism in any system with injection. Its main task is spraying of fuel on small particles directly in cylinders or in the required place of an air path of the engine. Nozzles of diesel and petrol engines perform approximately identical functions, however they are absolutely different devices on a design and the principle of the action.
The principle of work of a fuel nozzle consists in the following: from the pump with high pressure fuel passes into its union then it on the system of channels gets into a spray cavity. The subsequent movement of fuel is closed by a spray needle which is drawn in by a spring. At this time the pump of high pressure continues to lift fuel pressure up to the size which is capable to overcome resistance of a spring and to lift a needle over a saddle. So there is a fuel injection in a cylinder therefore again pressure falls, the needle sits down on a saddle again and cuts fuel supply, locking a system. With fuel forcing continuation the procedure repeats.
The main working condition in that case is a closing of a system after the end of injection of fuel. Otherwise supply of fuel at the next stage will be carried out not when pressure of a system is set and when giving by means of the pump begins. Thereof operation of the engine can become tougher, it will lose power, and the fuel nozzle in general can fail in connection with hit of products of combustion in an open system. In that case repair of nozzles which runs into money can be necessary.
Rehabilitation can be also promoted by washing of nozzles. This procedure implies washing away of pollution which collected in a system. The main ways of washing of nozzles are among: by means of special additives to fuel, washing by means of additional installation without dismantling of nozzles and with dismantling at the ultrasonic stand. The first way consists of periodic addition of special medicines in fuel. They wash out not only nozzles, but also all system. Cleaning without dismantling consists in activity of the engine on the specialized washing-out fuel. The last option of washing is used as a last resort for removal of the hardened deposits of the big sizes when the first two methods have no desirable effect.