Almost all passenger cars produced today are injection vehicles. This means that one of the most important elements of the engine, the injector, is engaged in fuel injection in the engine.
The purpose of a nozzle (or injector) in a car engine is to meter fuel, atomize it, form a mixture of air, gasoline (or diesel fuel). Modern engines are equipped with injectors with electronic fuel injection control. There are 3 types of injectors with different injection methods.
Electromagnetic
Gasoline engines are equipped with injectors with an electromagnetic method of action, incl. and engines with direct injection. The nozzle design is simple; is a nozzle, a solenoid valve connected to the needle. The injector operates in accordance with the operation of the control unit. At a certain time, voltage is applied to the valve - the resulting electromagnetic field, overcoming the resistance of the spring, draws in the needle, releasing the nozzle. As a result, petrol is injected. When the electronic unit stops supplying voltage, the electromagnetic field disappears, the needle returns to its original place, thanks to the elasticity of the spring.
Electro-hydraulic
Works in conjunction with diesel engines. The design includes a drain, an inlet throttle, a control chamber, a valve (electromagnetic). The essence of the work is to apply pressure. When the unit supplies the appropriate voltage to the valve, the drain throttle immediately opens - diesel fuel goes into the line.
The task of the intake throttle is to prevent the equalization of pressure in the line, the control chamber. As a result, the pressure on the piston decreases, but the fuel presses on the needle as before, which causes it to rise and fuel is injected. When the electronic unit de-energizes the valve, the injector needle is pressed against the seat due to the pressure of diesel fuel on the piston in the control chamber. Injection does not take place because the fuel presses on the needle less than on the piston.
Piezoelectric
It is considered the most advanced and is installed on diesel engines. Its main advantage is its high response speed (4 times more than that of electromagnetic injectors). The consequence of this is the ability to inject fuel several times during just one cycle, plus an accurate dosage. The design of the piezoelectric nozzle includes a switching valve, a needle, a piezoelectric element, and a pusher.
The principle of operation of this injector is also based on hydraulics. Initial position: the needle is in the seat due to the higher fuel pressure. When a voltage is applied to the piezoelectric element, its length increases, due to which force is transmitted to the pusher. This opens the changeover valve and the fuel flows into the line. Next, the needle rises and injection occurs.
