Fuel injector

A fuel injector including a needle and a pressure chamber defined by the rear surface of said needle, said needle being closed when a fuel pressure in said pressure chamber is raised, and said needle being opened when a fuel pressure in said pressure chamber is lowered, said fuel injector comprising;

• a pressure control chamber formed in a region adjacent to said pressure chamber;
• a restricted opening arranged between said pressure chamber and said pressure control chamber;
• a valve which opens when the pressure in said pressure control chamber exceeds the pressure in said pressure chamber by a predetermined amount, such that, when open, said valve permits fuel to flow from the pressure control chamber to the pressure chamber;
• an opening and closing valve which is opened when a fuel pressure in the pressure control chamber becomes lower than a fuel pressure in the pressure chamber by a predetermined first pressure, said restricted opening, said valve and said opening and closing valve being arranged between said pressure chamber and said pressure control chamber;
• and
• fuel pressure controlling means for controlling a fuel pressure in said pressure control chamber, said fuel pressure controlling means raising the fuel pressure in the pressure control chamber to introduce fuel in the pressure control chamber into the pressure chamber via the valve, said fuel pressure controlling means lowering the fuel pressure in the pressure control chamber to discharge fuel in the pressure chamber into the pressure control chamber via the restricted opening when the fuel pressure in the pressure chamber is lower than a predetermined second pressure and to discharge the fuel in the pressure chamber into the pressure control chamber via the opening and closing valve when the fuel pressure in the pressure chamber is higher than said predetermined second pressure.