Electromagnetic control injection systems for diesel engines of the pressure-time type where the injector needle is controlled by the charging and discharging of a chamber

Claim 1

An electromagnetic fuel injection system for a diesel engine, comprising: a fuel injector having a needle movable between an open position and a closed position for said fuel injector; means for moving said needle from said open to said closed position, said means for moving including a piston movable with said needle and a first fluid chamber communicating with said piston such that a fluid pressure in said first fluid chamber acts to move said piston toward a first position corresponding to said closed position; means for moving said needle from said closed position to said open position; means for controlling a rate of movement of said needle from said closed position to said open position; a three-way solenoid valve having a first port communicating with a source of pressurized fuel, a second port communicating with a fluid bypass and a third port, said three-way solenoid valve being positionable in a first position wherein said first and third ports are in communication, and a second position wherein said second and third ports are in communication; first conduit means connecting said third port with said first fluid chamber, said first conduit means including means defining first and second alternate parallel fuel flow paths, said first flow path defining a restriction in comparison to said second flow path and constituting said means for controlling, said second flow path being constructed so as to be open only for flow into said first fluid chamber; wherein said means defining first and second alternate parallel flow paths comprises: a valve element having a pressure loss circuit therein; and means for biasing said valve element into a position closing said first conduit means with only said pressure loss circuit communicating said first conduit means with said first fluid chamber so as to define said first flow path, wherein pressurized fuel from said three-way valve moves said valve element away from said position closing said first conduit means so as to define said second flow path, and wherein said piston and valve element are constructed so as to minimize the volume of said first fluid chamber.