Fuel injector

• US 6,604,507 B1
• Filed: 09/09/1999
• Issued: 08/12/2003
• Est. Priority Date: 09/10/1998
• Status: Expired due to Fees

• Current Assignee: International Engine Intellectual Property Company, LLC (Volkswagen AG)
• Original Assignee: International Engine Intellectual Property Company, LLC (Volkswagen AG)
• Inventors: Arnold, Steven C., Yang, Xilin, Lei, Ning
• Primary Examiner(s): MILLER, CARL STUART
• Application Number:
  US09/392,814
• Time in Patent Office: 1,433 Days
• Field of Search: 123/446, 123/500, 123/501, 123/299, 123/300, 123/467, 123/496
• US Class Current: 123/446
• CPC Class Codes: F02M 45/066 Having specially arranged spill port and spill contour on the piston F02M45/063 takes precedence
• CPC Class Codes: F02M 57/025 hydraulic, e.g. with pressure amplification
• CPC Class Codes: F02M 57/026 Construction details of pressure amplifiers, e.g. fuel passages or check valves arranged in the intensifier piston or head, particular diameter relationships, stop members, arrangement of ports or conduits
• CPC Class Codes: F02M 59/105 hydraulic drive F02M59/32 takes precedence
• CPC Class Codes: F02M 61/205 Means specially adapted for varying the spring tension or assisting the spring force to close the injection-valve, e.g. with damping of valve lift

Abstract

A fuel injector includes a spool control valve, a plunger which moves in a fuel pressure chamber between retracted and full stroke positions. The fuel injector may include a spill port for spilling fuel from the fuel pressure chamber, the spill port being open at the start and closed by the translating motion of the plunger to delay the start of injection. The fuel injector chamber may further include a control port which is closed at the start of plunger motion and is opened by the plunger to connect the pressure chamber to a needle back chamber to bias the needle valve closed. The needle back chamber becomes isolated from the pressure chamber by further movement of the plunger and includes a pressure control passage to allow the pressure therein to decay upon control port closure, thereby effecting split injection or rate shaping.

Claims

1. A fuel injector for generating a fuel injection event in the combustion chamber of an internal combustion engine, having a controller being shiftable from a first disposition toward a second disposition and returnably shiftable to the first disposition thereby defining initiation and termination of an injection event, such shifting acting to port an actuating fluid to stroke an intensifier plunger for compressing fuel in an intensifier pressure chamber, the intensifier pressure chamber having a fuel inlet port and being defined in part by a plunger head and further being in fluid communication with a needle valve, comprising;

at least a first spill port being operably disposed in fluid communication with the intensifier pressure chamber and being spaced apart from the plunger head when the intensifier plunger is in a retracted disposition, the spill port spilling fuel from the pressure chamber for a select duration of time after initiation of the intensifier plunger compressive stroke motion such that no fuel injection occurs during the select duration of time, termination of the select duration of time occurring when the plunger head seals off the first spill port, the intensifier plunger being directly fluidly in communication with a needle valve surface, fuel pressure on the surface acting to open the needle valve, the motion of the compressive stroke motion of the intensifier plunger generating fuel pressure at an injectable level acting on the needle valve surface to provide substantially continuous injected fuel from the time that the plunger head seals off the first spill port until interruption of the compressive stroke motion.

2. The fuel injector of claim 1 wherein translation of the intensifier plunger a preselected distance from the first retracted disposition acts to substantially seal off the spill port and the spill passageway.

3. The fuel injector of claim 2 wherein the spill passageway has a redetermined flow area.

4. The fuel injector of claim 1 wherein the duration of fuel spilling is substantially equal to the minimum duration of time required for the controller to make a round trip from the first disposition to the second disposition and back to the first disposition.

5. The fuel injector of claim 2 wherein the intensifier plunger is translatable in the intensifier pressure chamber between the first retracted disposition and a second disposition at full stroke, the spill port being disposed adjacent a head of the intensifier plunger when the intensifier plunger is in the first retracted disposition.

6. The fuel injector of claim 1 wherein the spill passageway is in fluid communication with a relatively low pressure fuel reservoir disposed external to the fuel injector.

7. The fuel injector of claim 1 wherein the spill passageway effects spilling of fuel from the pressure chamber for a time after commencement of the stroke of the intensifier plunger, the time being of sufficient duration to ensure that the controller is operating in a stable and predictable mode of fuel delivery operation.

8. The fuel injector of claim 1 wherein the spill passageway has a predetermined flow area.

9. The fuel injector of claim 8 wherein the spill passageway flow area is predetermined to ensure spillage of fuel for a time duration of sufficient length to permit the controller to make a round trip from the first disposition to the second disposition and back to the first disposition.

10. The fuel injector of claim 1 wherein the spill passageway effects a selected hydraulic delay between the initiation of an actuation command to the controller and the commencement of fuel injection.

11. A hydraulically-actuated, electronically controlled fuel injector comprising:

a control valve spool that is electronically actuated, translation of said control valve spool from a first position to a second position acting to port an actuating fluid to an intensifier plunger responsive to an electronic actuation command, the intensifier plunger compressively stroking under the urging of the actuating fluid, the stroke increasing the pressure of fuel in an intensifier pressure chamber, the intensifier pressure chamber having a fuel inlet, the fuel being deliverable directly from the intensifier pressure chamber to a needle valve orifice for injection into the combustion chamber of an internal combustion engine, the intensifier pressure chamber being in fluid communication with a needle valve opening piston surface during fuel injection, the injection fuel under pressure acting on the needle valve opening piston surface to effect translation of the needle valve and to thereby open the needle valve orifice;

a spill port in fluid communication with the intensifier pressure chamber, the spill port being spaced apart from the intensifier plunger prior to initiation of the intensifier plunger compressive stroke and being open for at least a portion of the stroke of the intensifier plunger for spilling fuel from the intensifier pressure chamber, the spilling of fuel effecting a hydraulic delay in commencement of fuel injection, the delay occurring between the electronic actuation of the control valve and closing of the spill port by the intensifier plunger during the intensifier plunger compressive stroke.

12. The fuel injector of claim 11 wherein a flow area of the spill port is selected to effect a desired hydraulic delay.

13. The fuel injector of claim 12 wherein the duration of hydraulic delay is selected to be substantially coterminous with a period of partial control valve translation.

14. The fuel injector of claim 13 wherein the control valve is translatable from a first disposition to a second disposition and returnably translatable to the first disposition, such translation defining a round trip, a partial control valve translation being less than a round trip.

15. The fuel injector of claim 13 wherein the hydraulic delay effected by the spill port substantially prevents fuel injection during the period of partial control valve translation.

16. The fuel injector of claim 11 wherein the spillage through the spill port effects an acceleration of the intensifier plunger stroke resulting in greater intensifier plunger momentum.

17. The fuel injector of claim 14 wherein the fuel delivery volume during a minimum round trip per intensifier plunger stroke is substantially 1 mm³.

18. The fuel injector of claim 11 wherein the spill port is in fluid communication with a pressure bearing surface of the needle valve, spilled fuel pressure acting on the pressure bearing surface being opposed to the injection fuel under pressure acting on the needle valve to effect translation of the needle valve and to thereby open the needle valve orifice.

19. The fuel injector of claim 18 wherein the opposition to an opening force developed by the injection fuel under pressure acting on the needle valve acts to control the opening of the needle valve orifice for delivery of a reduced fuel injection volume.

20. The fuel injector of claim 18 wherein the opposition to an opening force developed by the injection fuel under pressure effects passive control of the opening of the needle valve orifice.

21. The fuel injector of claim 20 wherein the passive control of the opening of the needle valve orifice provides for limited initial injection volumes useful in rate shaping of the injection event and in pilot injection preceding a main injection event.

22. The fuel injector of claim 18 wherein the spill port provides for passive rate shaping of the injection event and pilot injection preceding a main injection event during a single round trip of the control valve, the single round trip of the control valve generating the full injection event.

23. The fuel injector of claim 18 further including a needle back chamber formed in part by the pressure bearing surface of the needle valve and in fluid communication with the spill port, the needle back chamber being vented by a needle back vent passage to a relatively low pressure area, the needle back vent passage having a flow area that is sized to throttle a flow of fuel from the needle back chamber as desired to effect a desired control of the needle valve opening and closing.

24. A fuel injector having an intensifier plunger, the intensifier plunger being translatable in a cylinder between a retracted position and a full stroke position, the cylinder being defined by a cylinder wall, the cylinder wall defining in part a variable volume intensifier pressure chamber, the intensifier pressure chamber having a fuel inlet port and being in direct fluid communication with a surface during the injection of fuel, a certain pressure bearing on the surface acting to open the needle valve, the fuel injector comprising:

a spill port intersecting the cylinder wall, the spill port being variably openable and closeable by the intensifier plunger during the translating motion of the intensifier piston for spilling fuel from the variable volume intensifier pressure chamber as desired such that no fuel injection occurs while the spill port is open.

25. The fuel injector of claim 24 wherein the spill port includes a spill passageway defined in an injector body and being fluidly coupled to a low pressure area for the spilling of fuel to the low pressure area.

26. The fuel injector of claim 25 wherein the low pressure area is a fuel reservoir disposed external to a fuel injector body.

27. The fuel injector of claim 24 wherein the spill port includes a predetermined flow area.

28. The fuel injector of claim 24 further including a needle valve, the needle valve being translatable between an open position and a closed position, a fuel injection orifice being open in the needle valve open disposition, the needle valve having a needle back surface, the needle back surface defining in part a needle back chamber, the fuel injector further comprising:

the spill port including a spill passageway defined in an injector body and being fluidly coupled to the needle back surface.

29. The fuel injector of claim 28 wherein fuel under pressure spilled through the spill port acts on the needle back surface to control translation of the needle valve.

30. The fuel injector of claim 29 wherein fuel under pressure spilled through the spill port acts on the needle back surface to oppose forces acting on the needle valve tending to urge the needle to the open position.

31. The fuel injector of claim 28 further including a needle back vent passage, the needle back vent passage being in fluid communication with the needle back surface for venting of fuel therefrom.

32. The fuel injector of claim 31 further wherein the needle back vent passage is in fluid communication with a source of fuel disposed external to the injector.

33. The fuel injector of claim 32 further wherein the needle back vent passage is in fluid communication with a source of fuel disposed external to the injector for the venting of fuel thereto.

34. The fuel injector of claim 33 further wherein flow of fuel in the needle back vent passage is two way for selective venting of fuel from the needle back surface and for replenishing a volume of fuel at the needle back surface.

35. The fuel injector of claim 24 wherein the spill port is disposed adjacent an intensifier plunger lower piston head when the intensifier plunger is at the retracted disposition, the lower piston head for acting on fuel in the variable volume intensifier pressure chamber to increase the pressure thereof.

36. The fuel injector of claim 24 wherein the intensifier plunger acts cooperatively with the spill port to control the beginning of fuel injection.

37. The fuel injector of claim 24 wherein the intensifier plunger acts cooperatively with the spill port to delay the beginning of fuel injection with respect to initiation of intensifier plunger motion.

38. The fuel injector of claim 24 wherein the intensifier plunger acts cooperatively with the spill port to delay the beginning of fuel injection with respect to initiation of actuation of an injector control valve.

39. A fuel injector having an intensifier plunger, the intensifier plunger being translatable in a cylinder between a retracted position and a full stroke position, the cylinder being defined by a cylinder wall, the cylinder wall defining in part a variable volume intensifier pressure chamber, the intensifier pressure chamber having a fuel inlet port and being in direct fluid communication with a surface during the injection of fuel, a certain pressure bearing on the surface acting to open the needle valve, the fuel injector comprising:

a control valve having a spool shiftable between a first position and a second position, defining a round trip of the valve spool, the round trip being translating motion between the first position and the second position and a returning translating motion to the first position,

a spill port intersecting the cylinder wall, the spill port being variably openable and closeable by the intensifier plunger during the translating motion of the intensifier piston for spilling fuel from the variable volume intensifier pressure chamber as desired such that no fuel injection occurs until the spill port is closed by the intensifier plunger.

40. The fuel injector of claim 39 wherein the spill port is disposed adjacent to an intensifier plunger lower piston head when the intensifier plunger is at the retracted disposition, the lower piston head for acting on fuel in the variable volume intensifier pressure chamber to increase the pressure thereof.

41. The fuel injector of claim 39 wherein the spill port is disposed spaced apart from the intensifier plunger lower piston head less than 1.0 mm when the intensifier plunger is at the retracted disposition.

42. The fuel injector of claim 39 wherein the bottom of the spill port is disposed 0.6 mm from the intensifier plunger lower piston head when the intensifier plunger is at the retracted disposition.

43. The fuel injector of claim 39 wherein the spill port diameter is 0.6 mm.

44. The fuel injector of claim 39 wherein the intensifier plunger acts cooperatively with the spill port to control the beginning of fuel injection.

45. The fuel injector of claim 39 wherein the intensifier plunger acts cooperatively with the spill port to delay the beginning of fuel injection with respect to initiation of intensifier plunger valve motion.

46. The fuel injector of claim 39 wherein the intensifier plunger acts cooperatively with the spill port to delay the beginning of fuel injection with respect to initiation of actuation of the injector control valve spool.

47. The fuel injector of claim 42 wherein the intensifier plunger acts cooperatively with the spill port to delay the beginning of fuel injection with respect to initiation of actuation of the injector control valve spool for a duration that is at least equal in duration to a time of a minimum round trip of the control valve spool.

48. The fuel injector of claim 47 wherein the intensifier plunger acts cooperatively with the spill port to delay the beginning of fuel injection with respect to initiation of actuation of the injector control valve spool for a duration that is at least equal in duration to a time of a minimum round trip of the control valve spool.

49. A fuel injector having an intensifier plunger, the intensifier plunger being translatable in a cylinder between a retracted position and a full stroke position, the cylinder being defined by a cylinder wall, the cylinder wall defining in part a variable volume intensifier pressure chamber and being in direct fluid communication with a surface during an injection of fuel, a certain pressure bearing on the surface acting to open an injector needle valve to effect the fuel injection, the intensifier pressure chamber having a fuel inlet port, the fuel injector comprising:

a first control port, the control port being variably openable and closeable by the intensifier plunger during the translating motion of the intensifier piston for spilling fuel from the variable volume intensifier pressure chamber as desired to control the opening motion of the injector needle valve such that no fuel injection occurs when the control port is open.

50. The fuel injector of claim 49 wherein the control port includes a control port passageway, the control port passageway being fluidly coupled to a needle valve needle back surface.

51. The fuel injector of claim 50 wherein fuel under pressure spilled through the control port acts on the needle back surface to control translation of the needle valve.

52. The fuel injector of claim 51 wherein fuel under pressure spilled through the control port acts on the needle back surface to oppose a force acting on the needle valve tending to urge the needle valve to an open position.

53. The fuel injector of claim 50 further including a needle back vent orifice, the needle back vent orifice being in fluid communication with the needle back surface for venting of fuel therefrom.

54. The fuel injector of claim 53 further wherein the needle back vent orifice is in fluid communication with a source of fuel disposed external to the injector.

55. The fuel injector of claim 54 further wherein the needle back vent orifice is in fluid communication with a source of fuel disposed external to the injector for the venting of fuel thereto.

56. The fuel injector of claim 55 further wherein flow of fuel in the needle back vent orifice is two way for selective venting of fuel from the needle back surface and for replenishing a volume of fuel at the needle back surface.

57. A fuel injector having an intensifier plunger and a needle valve, the intensifier plunger being translatable in a cylinder between a retracted position and a full stroke position, the cylinder being defined by a cylinder wall, the cylinder wall defining in part a variable volume intensifier pressure chamber, the needle valve being translatable between an open position and a closed position, a fuel injection orifice being open in the needle valve open disposition, the needle valve having a needle back surface, the needle back surface defining in part a needle back chamber, the fuel injector comprising:

a control port including a control port passageway being fluidly couplable to the needle back surface.

58. The fuel injector of claim 57 wherein fuel under pressure spilled through the control port acts on the needle back surface to control translation of the needle valve.

59. The fuel injector of claim 58 wherein fuel under pressure spilled through the control port acts on the needle back surface to oppose a force acting on the needle valve tending to urge the needle to the open position.

60. The fuel injector of claim 57 further including a needle back vent orifice, the needle back vent orifice being in fluid communication with the needle back surface for venting of fuel therefrom.

61. The fuel injector of claim 60 further wherein the needle back vent orifice is in fluid communication with a source of fuel disposed external to the injector.

62. The fuel injector of claim 61 further wherein the needle back vent orifice is in fluid communication with a source of fuel disposed external to the injector for the venting of fuel thereto.

63. The fuel injector of claim 62 further wherein flow of fuel in the needle back vent orifice is two way for selective venting of fuel from the needle back surface and for replenishing a volume of fuel at the needle back surface.

64. The fuel injector of claim 57 wherein a controlling spillage of fuel occurs at a time subsequent to initiation of intensifier plunger motion, the controlling spillage effecting a split injection of fuel injected from the fuel injection orifice.

65. The fuel injector of claim 57 wherein a controlling spillage of fuel occurs at a time subsequent to initiation of intensifier plunger motion, the controlling spillage effecting a rate shaping of fuel injected from the fuel injection orifice.

66. The fuel injector of claim 57 wherein a controlling spillage of fuel occurs at a time subsequent to initiation of intensifier plunger motion, the controlling spillage effecting passive control of needle valve closing during an injection event.

74. The fuel injector of claim 57 wherein a controlling spillage of fuel occurs at a time subsequent to initiation of intensifier plunger motion, the controlling spillage effecting a split injection of fuel injected from the fuel injection orifice.

75. The fuel injector of claim 57 wherein a controlling spillage of fuel occurs at a time subsequent to initiation of intensifier plunger motion, the controlling spillage effecting a rate shaping of fuel injected from the fuel injection orifice.

76. The fuel injector of claim 57 wherein a controlling spillage of fuel occurs at a time subsequent to initiation of intensifier plunger motion, the controlling spillage effecting passive control of needle valve closing during an injection event.

77. The fuel injector of claim 57 wherein a controlling spillage of fuel occurs at a time subsequent to initiation of intensifier plunger motion, the controlling spillage effecting bypass of a partial motion of a control spool valve.

67. A fuel injector having an intensifier plunger, the intensifier plunger being translatable in a cylinder between a retracted position and a full stroke position, the cylinder being defined by a cylinder wall, the cylinder wall defining in part a variable volume intensifier pressure chamber, the fuel injector comprising:

a first control port, the first control port being variably openable and closeable by the intensifier plunger during the translating motion of the intensifier piston for spilling fuel from the variable volume intensifier pressure chamber as desired to control the opening motion of an injector needle valve; and

a second control port, the second control port being variably openable and closeable by the intensifier plunger during the translating motion of the intensifier piston for spilling fuel from the variable volume intensifier pressure chamber as desired to control the opening motion of the injector needle valve.

68. The fuel injector of claim 67 wherein fuel under pressure spilled through the control port acts on a needle surface to urge the needle valve to a closed position.

69. The fuel injector of claim 68 wherein fuel under pressure spilled through the control port acts on the needle surface to oppose a force acting on the needle valve tending to urge the needle to the open position.

70. The fuel injector of claim 67 further including a needle vent orifice, the needle vent orifice being in fluid communication with the needle surface for venting of fuel therefrom.

71. The fuel injector of claim 70 further wherein the needle vent orifice is in fluid communication with a source of fuel disposed external to the injector.

72. The fuel injector of claim 71 further wherein the needle vent orifice is in fluid communication with a source of fuel disposed external to the injector for the venting of fuel thereto.

73. The fuel injector of claim 72 further wherein flow of fuel in the needle vent orifice is two way for selective venting of fuel from the needle surface and for replenishing a volume of fuel at the needle surface.

78. A fuel injector for generating a fuel injection event in the combustion chamber of an internal combustion engine, having a controller being shiftable from a first disposition toward a second disposition and returnably shiftable to the first disposition, such shifting acting to port an actuating fluid to stroke an intensifier plunger for compressing fuel in an intensifier pressure chamber, the pressure chamber being in direct fluid communication with a surface during an injection of fuel, a certain pressure bearing on the surface acting to open an injector needle valve to effect the fuel injection, the intensifier pressure chamber having a fuel inlet port, comprising:

a spill passageway operably disposed in fluid communication with the intensifier pressure chamber, the spill passageway spilling fuel from the pressure chamber for a select duration of time after initiation of the intensifier plunger compressive stroke motion, the spill passageway effecting a selected hydraulic delay between the initiation of an actuation command to the controller and the commencement of fuel injection the spill passageway having a spill port opening into the intensifier pressure chamber, the spill port being open when the intensifier plunger is in a first retracted position.

79. A fuel injector having an intensifier plunger, the intensifier plunger being translatable in a cylinder between a retracted position and a full stroke position, the cylinder being defined by a cylinder wall, the cylinder wall defining in part a variable volume intensifier pressure chamber, the pressure chamber being in direct fluid communication with a surface during an injection of fuel, a certain pressure bearing on the surface acting to open an injector needle valve to effect the fuel injection, the intensifier pressure chamber having a fuel inlet port, the fuel injector comprising:

a spill port intersecting the cylinder wall, the spill port being variably openable and closeable by the intensifier plunger during the translating motion of the intensifier piston for spilling fuel from the variable volume intensifier pressure chamber as desired, the intensifier plunger acting cooperatively with the spill port to delay the beginning of fuel injection with respect to initiation of intensifier plunger valve motion.

80. A fuel injector having an intensifier plunger, the intensifier plunger being translatable in a cylinder between a retracted position and a full stroke position, the cylinder being defined by a cylinder wall, the cylinder wall defining in part a variable volume intensifier pressure chamber, the pressure chamber being in direct fluid communication with a surface during an injection of fuel, a certain pressure bearing on the surface acting to open an injector needle valve to effect the fuel injection, the intensifier pressure chamber having a fuel inlet port, the fuel injector comprising:

a spill port intersecting the cylinder wall, the spill port being variably openable and closeable by the intensifier plunger during the translating motion of the intensifier piston for spilling fuel from the variable volume intensifier pressure chamber as desired, the intensifier plunger acting cooperatively with the spill port to delay the beginning of fuel injection with respect to initiation of actuation of an injector control valve.

81. A fuel injector having an intensifier plunger, the intensifier plunger being translatable in a cylinder between a retracted position and a full stroke position, the cylinder being defined by a cylinder wall, the cylinder wall defining in part a variable volume intensifier pressure chamber, the pressure chamber being in direct fluid communication with a surface during an injection of fuel, a certain pressure bearing on the surface acting to open an injector needle valve to effect the fuel injection, the intensifier pressure chamber having a fuel inlet port, the fuel injector comprising:

a spill port intersecting the cylinder wall, the spill port being variably openable and closeable by the intensifier plunger during the translating motion of the intensifier piston for spilling fuel from the variable volume intensifier pressure chamber as desired, the intensifier plunger acting cooperatively with the spill port to delay the beginning of fuel injection with respect to initiation of actuation of an injector control valve.

82. A fuel injector having an intensifier plunger, the intensifier plunger being translatable in a cylinder between a retracted position and a full stroke position, the cylinder being defined by a cylinder wall, the cylinder wall defining in part a variable volume intensifier pressure chamber, the pressure chamber being in direct fluid communication with a surface during an injection of fuel, a certain pressure bearing on the surface acting to open an injector needle valve to effect the fuel injection, the intensifier pressure chamber having a fuel inlet port, the fuel injector comprising:

a control valve having a spool shiftable between a first position and a second position by magnetic action, defining a round trip of the valve spool, the round trip being translating motion between the first position and the second position and a returning translating motion to the first position,

a spill port intersecting the cylinder wall, the spill port being variably openable and closeable by the intensifier plunger during the translating motion of the intensifier piston for spilling fuel from the variable volume intensifier pressure chamber as desired; and

the intensifier plunger acting cooperatively with the spill port to control the beginning of fuel injection.

83. A fuel injector having an intensifier plunger, the intensifier plunger being translatable in a cylinder between a retracted position and a full stroke position, the cylinder being defined by a cylinder wall, the cylinder wall defining in part a variable volume intensifier pressure chamber, the pressure chamber being in direct fluid communication with a surface during an injection of fuel, a certain pressure bearing on the surface acting to open an injector needle valve to effect the fuel injection, the intensifier pressure chamber having a fuel inlet port, the fuel injector comprising:

a control valve having a spool shiftable between a first position and a second position by magnetic action, defining a round trip of the valve spool, the round trip being translating motion between the first position and the second position and a returning translating motion to the first position,

a spill port intersecting the cylinder wall, the spill port being variably openable and closeable by the intensifier plunger during the translating motion of the intensifier piston for spilling fuel from the variable volume intensifier pressure chamber as desired; and

the intensifier plunger acting cooperatively with the spill port to delay the beginning of fuel injection with respect to initiation of intensifier plunger valve motion.

84. A fuel injector having an intensifier plunger, the intensifier plunger being translatable in a cylinder between a retracted position and a full stroke position, the cylinder being defined by a cylinder wall, the cylinder wall defining in part a variable volume intensifier pressure chamber, the pressure chamber being in direct fluid communication with a surface during an injection of fuel, a certain pressure bearing on the surface acting to open an injector needle valve to effect the fuel injection, the intensifier pressure chamber having a fuel inlet port, the fuel injector comprising:

a control valve having a spool shiftable between a first position and a second position by magnetic action, defining a round trip of the valve spool, the round trip being translating motion between the first position and the second position and a returning translating motion to the first position,

a spill port intersecting the cylinder wall, the spill port being variably openable and closeable by the intensifier plunger during the translating motion of the intensifier piston for spilling fuel from the variable volume intensifier pressure chamber as desired; and

the intensifier plunger acting cooperatively with the spill port to delay the beginning of fuel injection with respect to initiation of actuation of the injector control valve spool.

85. A fuel injector having an intensifier plunger, the intensifier plunger being translatable in a cylinder between a retracted position and a full stroke position, the cylinder being defined by a cylinder wall, the cylinder wall defining in part a variable volume intensifier pressure chamber, the pressure chamber being in direct fluid communication with a surface during an injection of fuel, a certain pressure bearing on the surface acting to open an injector needle valve to effect the fuel injection, the intensifier pressure chamber having a fuel inlet port, the fuel injector comprising:

a control valve having a spool shiftable between a first position and a second position by magnetic action, defining a round trip of the valve spool, the round trip being translating motion between the first position and the second position and a returning translating motion to the first position,

a spill port intersecting the cylinder wall, the spill port being variably openable and closeable by the intensifier plunger during the translating motion of the intensifier piston for spilling fuel from the variable volume intensifier pressure chamber as desired; and

the intensifier plunger acting cooperatively with the spill port to delay the beginning of fuel injection with respect to initiation of actuation of the injector control valve spool.

86. A fuel injector having an intensifier plunger, the intensifier plunger being translatable in a cylinder between a retracted position and a full stroke position, the cylinder being defined by a cylinder wall, the cylinder wall defining in part a variable volume intensifier pressure chamber, the pressure chamber being in direct fluid communication with a surface during an injection of fuel, a certain pressure bearing on the surface acting to open an injector needle valve to effect the fuel injection, the intensifier pressure chamber having a fuel inlet port, the fuel injector comprising:

a control valve having a spool shiftable between a first position and a second position by magnetic action, defining a round trip of the valve spool, the round trip being translating motion between the first position and the second position and a returning translating motion to the first position,

a spill port intersecting the cylinder wall, the spill port being variably openable and closeable by the intensifier plunger during the translating motion of the intensifier piston for spilling fuel from the variable volume intensifier pressure chamber as desired; and

the intensifier plunger acting cooperatively with the spill port to delay the beginning of fuel injection with respect to initiation of actuation of the injector control valve spool.

87. The fuel injector of claim 86 wherein the intensifier plunger acts cooperatively with the spill port to delay the beginning of fuel injection with respect to initiation of actuation of the injector control valve spool for a duration that is at least equal in duration to a time of a minimum round trip of the control valve spool.