Common rail injector

A fuel injector for a common rail injection system comprising:

• an injector body having axially spaced inlet and injection portions, said injection portion defining an injection orifice, a nozzle chamber and a valve seat, said inlet portion comprising a rail inlet for receiving pressurized fuel supplied to said injector;
• an injector valve mounted in said body and engageable with said seat to prevent fuel communication through said injection orifice and during an injection event displaceable from said seat for injecting pressurized fuel through said orifice;
• a control unit disposed in said injector body comprising a control chamber and a control piston displaceable in said control chamber;
• a pump unit comprising a pump chamber and a pump piston coupled to said control piston displaceable in said pump chamber to define an injection pump stroke;
• a control valve assembly comprising at least one control valve disposed in fluid communication relationship between said rail inlet and said control and pump chambers for selectively controlling the supply of pressurized fuel in said pump chamber and said control chamber,
• so that fuel is controllably supplied to said pump chamber between injection events and the fuel pressure in said control chamber is vented by said control valve to start an injection whereby said injector valve is displaced by pressurized fuel produced by said pump stroke to inject pressurized fuel through said injection orifice.

A fuel injector for a common rail injection system comprising:

• an injector body having a rail inlet for receiving pressurized fuel supplied to said injector and an injection portion, said injection portion defining an injection orifice, a nozzle chamber and an interior valve seat;
• an injector valve mounted in said body and engageable with said seat to prevent fuel communication through said injection orifice and during an injection event displaceable from said seat for injecting pressurized fuel through said orifice;
• a control unit comprising a control chamber and a control piston displaceable in said control chamber;
• a pump unit comprising a pump chamber and a pump piston displaceable in said pump chamber;
• nozzle conduit means for fluidly connecting said pump chamber and said nozzle chamber;
• a control valve assembly comprising a control valve which selectively controls fluid communication between said rail inlet and said control and pump chambers for selectively controlling the supply of pressurized fuel in said pump chamber and said control chamber,
• a solenoid for operating said control valve;
• so that fuel is controllably supplied to said pump chamber between injection events and the pressure of fuel in said control chamber is selectively vented to start the injection whereby said injector valve is displaced by pressurized fuel in said nozzle chamber to inject pressurized fuel through said injection orifice.

A fuel injector for a common rail injection system comprising:

• an injector body having axially spaced inlet and injection portions, said injection portion defining an injection orifice, a nozzle chamber and an interior valve seat, said inlet portion comprising a rail inlet for receiving pressurized fuel supplied to said injector;
• an injector valve mounted in said body and engageable with said seat to prevent fuel communication through said injection orifice and during an injection event axially displaceable from said seat for injecting pressurized fuel through said orifice;
• a control unit comprising a control chamber and a control piston axially displaceable in said control chamber;
• a pump unit comprising a pump chamber and a pump piston axially displaceable in said pump chamber;
• a nozzle conduit connecting said pump chamber and said nozzle chamber;
• a control valve assembly comprising a control valve to provide selective fuel communication between said rail inlet and said control and pump chambers for controlling the supply of pressurized fuel in said pump chamber and said control chamber, said control valve comprising a three-way valve having a first position wherein pressure in said control chamber is vented, a second position wherein the control chamber and pump chamber is supplied with pressurized fuel and a third position wherein communication of fuel to said pump chamber is terminated,
• so that fuel is controllably supplied to said pump chamber between injection events and the fuel in said control chamber is selectively controlled to start an injection whereby said injector valve is displaced by pressurized fuel in said nozzle chamber to inject pressurized fuel through said injection orifice.

A fuel injector for a common rail injection system comprising:

• an injector body having axially spaced inlet and injection portions, said injection portion defining an injection orifice, a nozzle chamber and an interior valve seat, said inlet portion comprising a rail inlet for receiving pressurized fuel supplied to said injector;
• an injector valve mounted in said body and engageable with said seat to prevent fuel communication through said injection orifice and during an injection event axially displaceable from said seat for injecting pressurized fuel through said orifice;
• a control unit comprising a control chamber and a control piston axially displaceable in said control chamber;
• a pump unit comprising a pump chamber and a pump piston axially displaceable in said pump chamber;
• a nozzle conduit connecting said pump chamber and said nozzle chamber;
• a control valve assembly comprising a control valve chamber and a control valve to provide selective fuel communication between said rail inlet and said control and pump chambers for controlling the supply of pressurized fuel in said pump chamber and said control chamber;
• and
• a trim valve for selectively controlling the rate of fuel supplied to said control valve chamber,
• so that fuel is controllably supplied to said pump chamber between injection events and the fuel in said control chamber is selectively controlled to start an injection whereby said injector valve is displaced by pressurized fuel in said nozzle chamber to inject pressurized fuel through said injection orifice.

A fuel injector for a common rail injection system comprising:

• an injector body having axially spaced inlet and injection portions, said injection portion defining an injection orifice, a nozzle chamber and a valve seat, said inlet portion comprising a rail inlet for receiving pressurized fuel supplied to said injector;
• an injector valve mounted in said body and engageable with said seat to prevent fuel communication through said injection orifice and during an injection event displaceable from said seat for injecting pressurized fuel through said orifice;
• a control unit disposed in said injector body comprising a control chamber and a control piston displaceable in said control chamber;
• a pump unit comprising a pump chamber and a pump piston coupled to said control piston displaceable in said pump chamber to define an injection pump stroke;
• a third unit responsive to pressure supplied at said rail inlet comprising a third chamber and a third piston engageable with said control piston;
• a control valve assembly comprising at least one control valve disposed in fluid communication relationship between said rail inlet and said control and pump chambers for selectively controlling the supply of pressurized fuel in said pump chamber and said control chamber, said pump piston being displaced for the injection of pressurized fuel by opening said control valve to vent pressurized fuel from said control chamber,
• so that fuel is controllably supplied to said pump chamber between injection events and the fuel pressure in said control chamber is selectively controlled to start an injection whereby said injector valve is displaced by pressurized fuel produced by said pump stroke to inject pressurized fuel through said injection orifice.