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1. (EP3150839) FUEL INJECTOR
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Claims

1. A fuel injector (10) for a compression ignition internal combustion engine, the fuel injector comprising:

a fuel injection valve having an injection valve member (14) moveable, in use, under the influence of fuel pressure within a control chamber (20) acting upon it, between a closed position and an open position;

a high pressure fuel supply channel (22) to the control chamber (20);

a fuel outlet channel (24) leading from the control chamber (20) to a low pressure reservoir or drain;

an actuator operable to open and close a discharge valve (26) located in the fuel outlet channel (24);

a moveable plate (28) located in the control chamber (20) and arranged to move into and out of contact with a sealing surface (34) of the control chamber (20);

a spill orifice (40) provided in the moveable plate (28) and arranged to communicate with the fuel outlet channel (24) when the moveable plate (28) is located in contact with the sealing surface (34) of the control chamber (20), the spill orifice (40) defining a restricted flow path for fuel to flow out of the control chamber (20) to the fuel outlet channel (24); and

an inlet orifice (38) provided in the moveable plate (28) and arranged to communicate with the high pressure fuel supply channel (22) when the moveable plate (28) is located in contact with the sealing surface (34) of the control chamber (20), the inlet orifice (38) defining a restricted flow path for fuel to flow from the high pressure fuel supply channel (22) into the control chamber (20)characterised in that the moveable plate (28) is configured such that one or more additional fluid passages (60a, 60b, 62a, 62b), defined at least in part by formations such as flats or grooves (60a, 60b, 62a, 62b) in a periphery of the moveable plate (28), are between the control chamber (20) and the high pressure fuel supply channel (22) to permit fuel flow therethrough when the moveable plate (28) is moved out of contact with the sealing surface (34) of the control chamber (20).


  2. The fuel injector of Claim 1, wherein, in use when the moveable plate (28) is in contact with the sealing surface (34) of the control chamber (20) and the discharge valve (26) is open, fuel flows from the high pressure fuel supply channel (22) into the control chamber (20) through the inlet orifice (38), and fuel flows out of the control chamber (20) through the spill orifice (40) and through the fuel outlet channel to the low pressure reservoir or drain.
  3. The fuel injector of Claim 1, wherein, in use when the moveable plate (28) moves out of contact with the sealing surface (34) of the control chamber (20), fuel flows from the high pressure fuel supply channel (22) into the control chamber (20) through the additional fluid passage(s) and through the inlet orifice (38) and spill orifice (40) in the moveable plate (28).
  4. The fuel injector of Claim 3, wherein the high pressure fuel supply channel (22) upstream of the additional fluid passage(s) is substantially unrestricted.
  5. The fuel injector of any preceding claim, further comprising bias means (36) provided in the control chamber (20) for biasing the moveable plate (28) into contact with the sealing surface (34) of the control chamber (20).
  6. The fuel injector of any preceding claim, wherein the inlet orifice (38) is located substantially centrally in the moveable plate (28).
  7. The fuel injector of Claim 6, wherein the spill orifice (40) is laterally offset from the inlet orifice (38).
  8. The fuel injector of any preceding claim, wherein the moveable plate (28) comprises a substantially central recess (42) via which the inlet orifice (38) communicates with the high pressure fuel supply channel (22) when the moveable plate (28) is in contact with the sealing surface (34) of the control chamber (20).
  9. The fuel injector of Claim 8, wherein the substantially central recess (42) is defined by an inner wall (44) of the moveable plate (28), and wherein the inner wall comprises a sealing surface arranged to seal against the sealing surface of the control chamber when the moveable plate is in contact with the sealing surface (34) of the control chamber (20).
  10. The fuel injector of any preceding claim, wherein the moveable plate (28) comprises an annular recess (50) via which the spill orifice (40) communicates with the fuel outlet channel (24) when the moveable plate is in contact with the sealing surface (34) of the control chamber (20).
  11. The fuel injector of Claim 10 when dependent on Claim 9, wherein the annular recess (50) is defined between an outer wall (52) of the moveable plate (28) and the inner wall (44) of the moveable plate (28), and wherein the outer wall (52) comprises a sealing surface arranged to seal against the sealing surface (34) of the control chamber (20) when the moveable plate (28) is in contact with the sealing surface (34) of the control chamber (20).
  12. The fuel injector of Claim 10 or Claim 11 when dependent upon Claim 8 or Claim 9, wherein the annular recess (50) and the substantially central recess (42) are substantially concentric.
  13. The fuel injector of any preceding claim, wherein the actuator is a solenoid actuator.