Fuel injection system for internal combustion engine

A fuel injection system for an internal combustion engine comprising:

• a source of high pressure fuel supply hydraulically connected with a fuel tank or reservoir which stores liquid fuel therein through a lower pressure supply pump;
• an accumulator which accumulates therein high pressure fuel from said high pressure fuel supply source;
• injection valve means having a body formed with an axial bore and a nozzle hole;
• a pressure regulator valve means which adjusts the pressure of fuel which is to be coupled to said body;
• plunger means axially slidable in the axial bore of said body of said injection valve means;
• said body having a fuel induction passageway means at one end of which high pressure fuel from said source of high pressure fuel supply is constantly communicated, the other end of said fuel induction passageway means being open into the axial bore of said body;
• said plunger means having a passageway means therein permitting hydraulic communication between said fuel induction passageway means of the body and a nozzle hole therethrough;
• drive means driving said plunger means for a downward or injection stroke and an upward or return stroke in the axial bore of said body, whereby injection of fuel under high pressure is started when said passageway means in said plunger means is communicated with said fuel induction passageway and said nozzle hole in said body upon the injection stroke of said plunger means and terminated when communication between said passageway and said nozzle hole is interrupted upon the return stroke of said plunger means;
• and
• electric control means for controlling the operations of said drive means and said pressure regulator valve means, said electric control means comprising a control unit and pressure sensor means for sensing the injection pressure, said pressure sensor means comprising a pick-up means disposed in a passage which entends from said pressure regulator valve means to said injection valve means, said electric control means also comprising a stroke sensor means sensing the axial position of said plunger means, said electric control means further comprising revolution sensor means sensing the speed of said engine, whereby said electric control means is operable to control the operation of said drive means to thereby control the injection starting and terminating points at controlled timing and also to control the guantity of the injection of fuel in response to output signals from said stroke sensor means, said revolution sensor means and said pressure sensor means.