Piezoelectric controlled common rail injector with hydraulic amplification of piezoelectric stroke

A fuel injector for internal combustion engines comprising:

• a control valve housed in a body of the injector;
• an electrical actuator device for operating said control valve;
• an injector valve, housed in an end of said body, fitted with a nozzle needle that opens under the pressure of fuel fed by a feeding line, said needle retracting from its seat when the counter pressure contained in a control chamber, and acting on a power piston that is mechanically connected to the coaxial nozzle needle, is reduced in consequence of the control valve actuation hydraulically connected drain duct to said control chamber, wherein:
• said electrical actuator device operates a first fluid-tight piston that faces onto a first chamber which is filled with fuel at a low pressure;
• and
• a second fluid-tight piston also faces the aforementioned first chamber, said second piston having an effective surface area smaller than that of said first piston;
• said second piston operates a sealing component of said control valve, which is housed on the inside of a second chamber hydraulically connected to said control chamber, across a drain hole of said control valve;
• wherein the pressure of the fuel contained in said first chamber causes the constant contact of said second piston with said sealing component of said control valve.