Fuel injector with direct needle valve control

• US 6,684,853 B1
• Filed: 08/02/1999
• Issued: 02/03/2004
• Est. Priority Date: 10/16/1998
• 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: Lei, Ning
• Primary Examiner(s): MILLER, CARL STUART
• Application Number:
  US09/365,965
• Time in Patent Office: 1,646 Days
• Field of Search: 123/446, 123/447, 123/500, 123/501, 123/300, 123/502, 123/299, 123/496, 123/467
• US Class Current: 123/446
• CPC Class Codes: F02M 45/04 with a small initial part , e.g. initial part for partial load and initial and main part for full load
• CPC Class Codes: F02M 47/027 Electrically actuated valves draining the chamber to release the closing pressure
• CPC Class Codes: F02M 57/025 hydraulic, e.g. with pressure amplification
• CPC Class Codes: F02M 63/0007 using electrically actuated valves injection valves F02M51/06
• CPC Class Codes: F02M 63/0225 Fuel-injection apparatus having a common rail feeding several injectors F02M63/0003 takes precedence; Means for varying pressure in common rails; Pumps feeding common rails

Abstract

A hydraulically-actuated unit fuel injector of the intensifier type is provided with two independently operable active control valves. A selectively actuable fuel pressure control valve is disposed on the hydraulic actuation fluid side to control the fuel pressure actuation process and provide a window of injection opportunity wherein the fuel pressure is maintained at high pressure. A selectively actuable timing control valve is disposed on the high pressure fuel side to provide precise control of injection timing events and duration, such as start of injection, end of injection, timing of interruption and duration of interruption, which all may occur during a single injection event within the window of opportunity. Both control valves are independently controlled to prevent reverse motion of the intensifier piston and plunger during dwell or interruption of injection while maintaining the full injection pressure. Dwell or interruption is controlled by using the timing control valve to port fuel under pressure to a fuel injector needle valve surface to generate a force on the fuel injector needle valve surface acting to close the fuel injector needle valve. Methods of defining a fuel injection event fuel injector having a fuel pressure intensifier, includes the steps of (a) preparing fuel pressure with a fuel injection pressure control valve, and (b) controlling the timing of a fuel injection event with a fuel injection timing control valve, the fuel pressure preparation and the timing of the fuel inject event being independently controllable. Preferably, full intensified fuel pressure is made available to the injector throughout a single injection event which may include a pilot injection, a main injection, a rate-shaped injection, and dwell periods wherein no injection occurs. Various methods of operating the fuel injector to provide various functions during a single injection event are also disclosed.

Claims

1. A fuel injector having a fuel pressure intensifier for increasing the pressure of a volume of fuel to a selected relatively high level, the fuel being admitted to the fuel injector at a pressure that is less than the pressure required to cause opening of an injector needle valve, the fuel intensifier being in fluid communication with the needle valve, the needle valve being openable for injection of fuel into a combustion chamber during an injection event, comprising:

an injection pressure control valve for preparing fuel pressure being fluidly coupled to the fuel pressure intensifier for controlling an injection event by porting a non-fuel actuating fluid to the fuel pressure intensifier; and

a fuel injection timing controller having a single control valve for controlling the timing of delivery of fuel to a combustion chamber during the injection event, the fuel injection pressure control valve being independently controllable for maintaining fuel at the selected relatively high level of pressure to the needle valve during the injection event to effect fuel injection and the fuel injection timing control valve for selectively interrupting fuel injection from the needle valve if desired during the injection event by controlling a flow of intensifier pressurized fuel to the needle valve by selectively porting fuel to a controller chamber in fluid communication with the needle valve, the controller chamber having a continuously open drain orifice.

2. The fuel injector of claim 1 wherein the fuel injection pressure control valve opens a window of injection opportunity and the fuel injection timing control valve controls the timing and duration of an injection event that occurs within the window of injection opportunity.

3. The fuel injector of claim 2 wherein the fuel injection pressure control valve opens a window of injection opportunity during which an actuation pressure is made available for use to intensify a fuel pressure.

4. The fuel injector of claim 2 wherein the fuel injection timing control valve controls the timing and duration of an injection event that occurs within the window of injection opportunity to define fuel injection parameters.

5. The fuel injector of claim 4 wherein the fuel injection parameters occurring within an injection event include at least one of the parameters being start of injection, end of injection, interruption of injection, timing of interruption of injection, and duration of interruption of injection, said parameters being attainable while maintaining fuel at the selected relatively high level of pressure to the needle valve.

6. The fuel injector of claim 1 wherein the fuel injection timing control valve provides for selective independent control of pilot injection, main injection and rate shaping within a single shot injection event.

7. The fuel injector of claim 1 wherein fuel injection pressure preparation and fuel injection timing control are internally determined and are decoupled.

8. The fuel injector of claim 1 wherein the fuel injection timing control valve has relatively less flow area in relation to the fuel injection pressure control valve, the lesser flow area enhancing the response time of the fuel injection timing control valve for improving the shaping of the injection event as desired.

9. The fuel injector of claim 1 wherein the fuel injection pressure control valve for preparing fuel pressure is cycled opened and closed a single time during each injection event and the fuel injection timing control valve may be independently cycled opened and closed a plurality of cycles during single time during each injection event for effecting shaping of the injection event as desired while maintaining fuel at the selected relatively high level of pressure to the needle valve.

51. The fuel injector of claim 1 wherein preparing fuel pressure and controlling the timing of a fuel injection event are internally determined and are decoupled.

53. The method of claim 1 further comprising the steps prior to opening said needle valve of bleeding off an initial portion of said quantity of fuel and ending said bleeding after a predetermined travel of said plunger.

55. The method of claim 1 further comprising the step prior to again closing said fuel pressure control valve of closing said needle valve.

10. A needle valve controller for use in a fuel injector, the fuel injector having a fuel inlet and a non-fuel actuating fluid inlet, fuel pressure at the inlet being admitted to the fuel injector at a pressure that is less than the pressure required to cause opening of an injector needle valve, the needle valve controller acting in cooperation with an actuating fluid controller disposed in the fuel injector, the actuating fluid controller effecting a known injection rate profile during an injection event by controlling the operation of a fuel intensifier, comprising:

a single selectively actuatable timing control valve being in flow communication with a source of intensifier pressurized fuel and being in flow communication with a fuel injector needle valve surface, the timing control valve being shiftable between an open and a closed disposition;

a controller operably coupled to the timing control valve for controlling the shifting of the timing control valve between the valve open and closed dispositions, opening the timing control valve acting to port fuel under pressure to the fuel injector needle valve surface, the fuel generating a force on the fuel injector needle valve surface acting to close the fuel injector needle valve without spilling a high pressure fuel ported to the needle valve for injection therefrom, the shifting of the timing control valve being effected only during those injection events where modification of the known fuel injection rate is desired.

11. The needle valve controller of claim 10, the controller including a solenoid, activation of the solenoid acting to shift the timing control valve to the open disposition.

12. The needle valve controller of claim 11 the controller further including a timing control valve spring, the spring exerting a closing bias on the control valve, the spring urging the control valve to the closed disposition.

13. The needle valve controller of claim 10 wherein flow communication with the fuel injector needle valve surface is via a bleed passageway defined in the fuel injector, the bleed passageway being fluidly coupled at a first end to the timing control valve and being fluidly coupled at a second end to a chamber, the chamber being defined in part by the fuel injector needle valve surface.

14. The needle valve controller of claim 13 wherein a drain orifice is fluidly coupled to the chamber and is further fluidly coupled to a low pressure fuel reservoir.

17. The needle valve controller of claim 14 wherein the diameter of the drain orifice is substantially 0.5 mm.

18. The needle valve controller of claim 13 wherein a refill passageway fluidly couples the chamber to a low pressure fuel reservoir, fuel in the low pressure fuel reservoir flowing in the refill passageway to refill the chamber.

19. The needle valve controller of claim 18 wherein a check valve is disposed in the refill passageway, the check valve being exposed to the fuel pressure in the low pressure fuel reservoir and in the chamber, opening and closing of the check valve being controlled by the fuel pressure acting thereon.

15. A needle valve controller for use in a fuel injector, the fuel injector having a fuel inlet and a non-fuel actuating fluid inlet, fuel pressure at the inlet being admitted to the fuel injector at a pressure that is less than the pressure required to cause opening of an injector needle valve, the needle valve controller acting in cooperation with an actuating fluid controller disposed in the fuel injector, the actuating fluid controller controlling an injection event by controlling the operation of a fuel intensifier, comprising:

a selectively actuatable timing control valve being in flow communication with a source of intensifier pressurized fuel and being in flow communication with a fuel injector needle valve surface, the timing control valve being shiftable between an open and a closed disposition;

a controller operably coupled to the timing control valve for controlling the shifting of the timing control valve between the valve open and closed dispositions, opening the timing control valve acting to port fuel under pressure to the fuel injector needle valve surface, the fuel generating a force on the fuel injector needle valve surface acting to close the fuel injector needle valve without spilling a high pressure fuel ported to the needle valve for injection therefrom, the shifting of the timing control valve being coordinated with, but independent of the actuating fluid controller to control fuel injection to a combustion chamber during the injection event, flow communication with the fuel injector needle valve surface being via a bleed passageway defined in the fuel injector, the bleed passageway being fluidly coupled at a first end to the timing control valve and being fluidly coupled at a second end to a chamber, the chamber being defined in part by the fuel injector needle valve surface a drain orifice is fluidly coupled to the chamber and is further fluidly coupled to a low pressure fuel reservoir, the drain orifice being at all time open to the low pressure fuel reservoir and being sized to throttle a flow of fuel from the chamber.

16. The needle valve controller of claim 15 wherein the diameter of the drain orifice is between 0.1 and 1.0 mm.

20. An electronically controlled hydraulically actuated unit injector having a fuel inlet, fuel pressure at the inlet being admitted to the unit injector at a pressure that is less than the pressure required to cause opening of an injector needle valve, comprising:

first and second controllers for cooperatively, independently controlling an injection event;

the first controller being actuated by a non-fuel actuating fluid admitted to the unit injector by an actuating fluid inlet and being in communication with a quantity of fuel in a chamber admitted to the chamber by a fuel inlet, the first controller for affecting the pressure of the fuel in the chamber for initiating and terminating an injection event; and

the second controller having a single valve, the single valve being in fluid communication with the fuel chamber and being in selective fluid communication with a controller chamber, the controller chamber being in fluid communication with an injection needle valve and having an open drain orifice, the needle valve being shiftable between a closed position and an open position for effecting fuel injection, the second controller for selectively controlling the opening and closing shifting of the needle valve by means of intensifier pressurized fuel to effect modulation of fuel injection during those injection events wherein such modulation is desired.

21. The fuel injector of claim 20 wherein the first controller opens a window of injection opportunity and the second controller controls the timing and duration of an injection event that occurs within the window of injection opportunity.

22. The fuel injector of claim 21 wherein the first controller opens a window of injection opportunity during which an actuation pressure is made available for use to intensify a fuel pressure.

23. The fuel injector of claim 21 wherein the second controller controls the timing and duration of an injection event that occurs within the window of injection opportunity to define fuel injection parameters.

24. The fuel injector of claim 23 wherein the fuel injection parameters include at least one of the parameters consisting of start of injection, end of injection, interruption of injection, timing of interruption of injection, and duration of interruption of injection, said parameters being attainable while maintaining fuel at the selected relatively high level of pressure to the needle valve.

25. The fuel injector of claim 20 wherein the second controller provides for selective independent control of pilot injection, main injection and rate shaping within a single shot injection event.

26. The fuel injector of claim 20 wherein fuel injection pressure preparation and fuel injection timing control are internally determined and are decoupled.

27. An electronically controlled hydraulically actuated unit injector having a fuel inlet and a needle valve, fuel pressure at the inlet being admitted to the fuel injector at a pressure that is less than the pressure required to cause opening of an injector needle valve, the needle valve being shiftable between an open and a closed position for providing an injection of high pressure fuel during a fuel injection event when in the open position, the injector comprising:

a first controller for initiating and terminating a fuel injection fuel event, the first controller being hydraulically actuated by a non-fuel actuating fluid and acting on fuel admitted to the unit injector at a pressure less than a pressure required to open the needle valve, said first controller causing high pressure fuel to be generated, the high pressure fuel being deliverable to the needle valve during the injection event for injection by the needle valve; and

a second controller having a single valve directly controlling a shifting of the needle valve between an open and a closed disposition by means of intensifier pressurized fuel, the second controller selectively controlling the shifting of the needle valve during the injection event to effect modulation of the fuel injection by selectively porting fuel to a controller chamber, the controller chamber being in fluid communication with the needle valve and having an open drain orifice;

the first controller and the second controller being independently actuated for cooperatively defining desired injection characteristics of the fuel injection event, the second controller being actuated only during those injection events when certain injection characteristics other than those achievable by the first controller acting alone are desired.

28. The fuel injector of claim 27 wherein the first controller opens a window of injection opportunity and the second controller controls the timing and duration of an injection event that occurs within the window of injection opportunity.

29. The fuel injector of claim 28 wherein the first controller opens a window of injection opportunity during which an actuation pressure is made available for use to intensify a fuel pressure.

30. The fuel injector of claim 28 wherein the second controller controls the timing and duration of an injection event that occurs within the window of injection opportunity to define fuel injection parameters.

31. The fuel injector of claim 30 wherein the fuel injection parameters include at least one of the parameters being start of injection, end of injection, interruption of injection, timing of interruption of injection, and duration of interruption of injection, said parameters being attainable while maintaining fuel at the selected relatively high level of pressure to the needle valve.

32. The fuel injector of claim 27 wherein the second controller provides for selective independent control of pilot injection, main injection and rate shaping within a single shot injection event.

33. The fuel injector of claim 27 wherein fuel injection pressure preparation and fuel injection timing control are internally determined and are decoupled.

34. An electronically controlled hydraulically actuated unit fuel injector having a fuel inlet and a needle valve, fuel pressure at the inlet being admitted to the fuel injector at a pressure that is less than the pressure required to cause opening of an injector needle valve, the needle valve being shiftable between an open and a closed position, an actuatable actuating fluid control valve for controlling a fuel pressure intensifier to define an injection event, the intensifier acting on a quantity of fuel admitted to the unit injector at a pressure that is less than the pressure required to shift the needle valve to an open disposition to increase the pressure of the quantity of fuel to a pressure at least equal to the pressure required to shift the needle valve to the open disposition, the intensifier being fluidly communicable with the needle valve for providing high pressure fuel substantially continuously for the duration of the injection event, the needle valve injecting a quantity of fuel during a fuel injection event at a known rate of injection as defined by the actuating fluid control valve, comprising:

a needle valve controller being decoupled from the actuating fluid control valve, the needle valve controller having a single valve, the single valve controlling a flow of intensifier pressurized fuel and being in fluid communication with the needle valve for controlling a shifting of the needle valve between an open and a closed position, the control exercised by the needle valve control means providing for the needle valve being shiftable through at least one cycle during the injection event to modify the known rate of injection during selected injection events where such modification is desired independent of the actuating fluid control valve.

35. The fuel injector of claim 34 wherein the actuating fluid control valve opens a window of injection opportunity and the needle valve controller controls the timing and duration of an injection event that occurs within the window of injection opportunity.

36. The fuel injector of claim 35 wherein the actuating fluid controller opens a window of injection opportunity during which an actuation pressure is made available for use to intensify a fuel pressure.

37. The fuel injector of claim 35 wherein the needle valve controller controls the timing and duration of an injection event that occurs within the window of injection opportunity to define fuel injection parameters.

38. The fuel injector of claim 37 wherein the fuel injection parameters include at least one of the parameters being start of injection, end of injection, interruption of injection, timing of interruption of injection, and duration of interruption of injection, said parameters being attainable without resort to spilling fuel form the injector.

39. The fuel injector of claim 34 wherein the needle valve controller provides for selective independent control of pilot injection, main injection and rate shaping within a single shot injection event.

40. The fuel injector of claim 34 wherein fuel injection pressure preparation and fuel injection timing control are internally determined and are decoupled.

41. A method of controlling fuel injection during a fuel injection event in an electronically controlled hydraulically actuated unit fuel injector, the injector having a fuel inlet and a non-fuel actuating fluid inlet, fuel pressure at the inlet being admitted to the fuel injector at a pressure that is less than the pressure required to cause opening of an injector needle valve, both inlets being selectively in fluid communication with a fuel pressure intensifier, having the steps of:

controlling the preparation of fuel pressure for a fuel injection event with a fuel injection pressure control valve;

generating high pressure fuel with the intensifier by means of a non-fuel actuating fluid;

providing high pressure fuel, the high pressure being available to a needle valve substantially continuously for the duration of the fuel injection event; and

independently controlling the timing of fuel injection from the needle valve during certain selected fuel injection events with a fuel injection timing controller having a single valve, thereby independently controlling the fuel pressure preparation and the timing of the fuel injection during any selected fuel injection event by means of controlling a flow of intensifier pressurized fuel to a controller chamber, the controller chamber being in fluid communication with the needle valve and having an open drain orifice.

42. The method of claim 41 wherein the preparation of the fuel pressure includes opening a window of injection opportunity and the timing control occurs within the window of injection opportunity.

43. The method of claim 42 including the step of providing an actuation pressure being made available to intensify a fuel pressure.

44. The fuel injector of claim 42 wherein the controlling the timing of a fuel injection event includes the step of defining fuel injection parameters occurring within a single injection event.

45. The method of claim 44 wherein the step of defining fuel injection parameters includes defining at least one of the parameters being start of injection, end of injection, interruption of injection, timing of interruption of injection, and duration of interruption of injection, said parameters being attainable while maintaining fuel at the selected relatively high level of pressure to the needle valve.

46. The method of claim 41 wherein controlling the timing of a fuel injection event provides for selective independent control of pilot injection, main injection and rate shaping within a single shot injection event while maintaining fuel at the selected relatively high level of pressure to the needle valve.

47. The method of claim 41 further comprising the step of supplying the fuel pressure from the fuel injection pressure control valve during the entire injection event.

48. The fuel injector of claim 47 wherein the controlling the timing of a fuel injection event includes the step of defining fuel injection parameters occurring within a single injection event.

49. The method of claim 48 wherein the step of defining fuel injection parameters includes defining at least one of the parameters being start of injection, end of injection, interruption of injection, timing of interruption of injection, and duration of interruption of injection, said parameters being attainable while maintaining fuel at the selected relatively high level of pressure to the needle valve.

50. The method of claim 47 wherein controlling the timing of a fuel injection event provides for selective independent control of pilot injection, main injection and rate shaping within a single shot injection event while maintaining fuel at the selected relatively high level of pressure to the needle valve.

52. A method of operating an electronically controlled hydraulically-actuated fuel injector to achieve a square fuel pressure rate of injection shape during a single injection event, said injector having a non-fuel actuating fluid inlet fluidly coupled to a fuel pressure control valve, the fuel pressure control valve controlling the position of a plunger operatively disposed to pressurize a quantity of fuel in a chamber, the chamber being in fluid communication with a fuel inlet, fuel pressure at the inlet being admitted to the fuel injector at a pressure that is less than the pressure required to cause opening of an injector needle valve, and a needle valve being in fluid communication with said quantity of fuel which may be opened and closed during an injection event, having the sequential steps of:

opening the fuel pressure control valve and moving said plunger to pressurize said quantity of fuel;

independently holding said needle valve in a closed position by means of a single valve shifting to port intensifier pressurized fuel to a controller chamber to act on the needle valve, the controller chamber having an open drain orifice;

after a predetermined duration, independently releasing the pressurized fuel acting on the needle valve;

opening said needle valve to permit injection;

maintaining said needle valve and said control valve open for a predetermined period;

actively closing said needle valve by means of the single valve porting pressurized fuel to act on the needle valve; and

closing said fuel pressure control valve.

54. A method of operating a hydraulically-actuated, electronically controlled fuel injector to achieve pilot injection with a long dwell duration during a single injection event, said injector having a fuel inlet and a fuel pressure control valve, fuel pressure at the inlet being admitted to the fuel injector at a pressure that is less than the pressure required to cause opening of an injector needle valve, the fuel pressure control valve controlling the position of a plunger operatively disposed to pressurize a quantity of fuel and the needle valve associated with said quantity of fuel being opened and closed during an injection event independently of the fuel pressure control valve, comprising:

opening the fuel pressure control valve and moving said plunger to pressurize said quantity of fuel and upon said fuel pressure exceeding a predetermined level, allowing said needle valve to open for a predetermined duration;

closing said needle valve by porting intensifier pressurized fuel to a controller chamber having an open drain orifice, the controller chamber being in fluid communication with the needle valve;

closing said fuel pressure control valve;

within the same injection event, after a predetermined dwell period, again opening the fuel pressure control valve and moving said plunger to pressurize said quantity of fuel allowing said needle valve to open;

maintaining said needle valve and said control valve open for a predetermined period; and

again closing said fuel pressure control valve.

56. A method of operating an electronically controlled hydraulically-actuated fuel injector to achieve rate-shaped injection during a single injection event, said injector having a fuel inlet and a non-fuel actuating fluid inlet fluidly coupled to a fuel pressure control valve, fuel pressure at the inlet being admitted to the fuel injector at a pressure that is less than the pressure required to cause opening of an injector needle valve, the fuel pressure control valve controlling the position of a plunger operatively disposed to pressurize a quantity of fuel in a chamber, the chamber being in fluid communication with a fuel inlet, and a needle valve being in fluid communication with said quantity of fuel which may be opened and closed during an injection event, having the steps of:

opening the fuel pressure control valve and moving said plunger to pressurize said quantity of fuel and upon said fuel pressure exceeding a predetermined level, allowing said needle valve to open for a predetermined duration;

with said fuel pressure control valve remaining open and without halting said motion of said plunger while maintaining fuel at the selected relatively high level of pressure to the needle valve, porting intensifier pressurized fuel by a single valve to a controller chamber having an open drain orifice and being in fluid communication with a needle valve surface to affect the needle valve surface for independently at least partially closing said needle valve;

after a very short predetermined dwell period, decreasing the pressure affecting the needle valve surface for independently allowing said needle valve to reopen;

maintaining said needle valve and said control valve open for a predetermined period; and

closing said fuel pressure control valve.

57. A hydraulically actuated, electronically controlled fuel injector being fluidly coupled to a source of low pressure fuel, fuel pressure being admitted to the fuel injector at a pressure that is less than the pressure required to cause opening of an injector needle valve, and having a fuel pressure intensifier, the fuel intensifier hydraulically amplifying the fuel pressure for injection at a relatively high pressure, comprising:

a fuel injection pressure control valve for preparing fuel pressure;

being in flow communication with a source of pressurized non-fuel actuating fluid and selectively porting such actuating fluid to the fuel intensifier for hydraulic amplification of the fuel pressure; and

a fuel injection timing control valve for controlling the timing of a fuel injection event by controlling a flow of intensifier pressurized fuel to a controller chamber, the controller chamber having an open drain orifice and being in fluid communication with the injector needle valve, the fuel injection pressure control valve and the fuel injection timing control valve being independently controllable.

58. The fuel injector of claim 57 wherein the fuel injection pressure control valve opens a window of injection opportunity and the fuel injection timing control valve controls the timing and duration of an injection event that occurs within the window of injection opportunity.

59. The fuel injector of claim 58 wherein the fuel injection pressure control valve opens a window of injection opportunity during which an actuation pressure is made available for use to intensify a fuel pressure.

60. The fuel injector of claim 58 wherein the fuel injection timing control valve controls the timing and duration of an injection event that occurs within the window of injection opportunity to define fuel injection parameters.

61. The fuel injector of claim 60 wherein the fuel injection parameters occurring within an injection event include at least one of the parameters being start of injection, end of injection, interruption of injection, timing of interruption of injection, and duration of interruption of injection.

62. The fuel injector of claim 57 wherein the fuel injection timing control valve provides for selective independent control of pilot injection, main injection and rate shaping within a single shot injection event.

63. The fuel injector of claim 57 wherein fuel injection pressure preparation and fuel injection timing control are internally determined and are decoupled.

64. The fuel injector of claim 57 wherein the fuel injection timing control valve has relatively less flow area in relation to the fuel injection pressure control valve, the lesser flow area enhancing the response time of the fuel injection timing control valve for improving the shaping of the injection event as desired.

65. The fuel injector of claim 57 wherein a full actuation pressure is available from the fuel injection pressure control valve for the duration of an injection event, thereby providing maximum injection pressure throughout the injection event without regard to shaping of the injection event as desired.

66. The fuel injector of claim 57 wherein the fuel injection pressure control valve for preparing fuel pressure is cycled opened and closed a single time during each injection event and the fuel injection timing control valve may be independently cycled opened and closed a plurality of cycles during single time during each injection event for effecting shaping of the injection event as desired.

67. A hydraulically actuated, electronically controlled unit injector having an inlet for admitting non-fuel actuating fluid to the injector and a fuel inlet for admitting a quantity of fuel at a pressure that is less than a pressure necessary to open a needle valve to cause fuel injection, an intensifier for selectively pressurizing the quantity of fuel to a pressure sufficient to open the needle valve when the intensifier is acted upon the actuating fluid, the pressurized fuel being available for control of the needle valve continuously during an injection event, the unit injector comprising:

a timing controller in fluid communication with the needle valve and with the intensifier, the timing controller being decoupled from actuation of the intensifier and controlling the shifting of the valve between an open and a closed disposition during an injection event by controlling a flow of pressurized fuel from the intensifier to a controller chamber having an open drain orifice, the controller chamber being in fluid communication with the needle valve.

68. The hydraulically actuated, electronically controlled unit injector of claim 67 wherein the timing controller directly controls the shifting of the needle valve.

69. The hydraulically actuated, electronically controlled unit injector of claim 68 wherein the timing controller directly controls the shifting of the needle valve by selectively porting a flow of pressurized fuel to exert a force on a needle valve surface, the force acting bias the needle valve in a closed disposition.

70. The hydraulically actuated, electronically controlled unit injector of claim 67 wherein the timing controller includes an electronically actuated controller valve, the controller valve being in fluid communication with a fuel passage extending between the intensifier and the needle valve, the fuel passage conveying high pressure fuel.

71. The hydraulically actuated, electronically controlled unit injector of claim 70 wherein the controller valve is in fluid communication with a controller chamber, the controller chamber being defined in part by a needle valve surface, the timing controller porting high pressure fuel to the needle valve surface when the controller valve is in an open disposition.

72. The hydraulically actuated, electronically controlled unit injector of claim 71 wherein the controller chamber is in fluid communication with a fuel reservoir via a fuel refill passage, the controller chamber being refilled with fuel when the controller valve is in a closed disposition.

73. A hydraulically actuated, electronically controlled unit injector having an inlet for admitting non-fuel actuating fluid to the injector and a fuel inlet for admitting a quantity of fuel at a pressure that is less than a pressure necessary to open a needle valve to cause fuel injection, an intensifier for selectively pressurizing the quantity of fuel to a pressure sufficient to open the needle valve when the intensifier is acted upon the actuating fluid, the pressurized fuel being available for control of the needle valve continuously during an injection event, the unit injector comprising:

a timing controller in fluid communication with the needle valve and with the intensifier being decoupled from actuation of the intensifier and controlling the shifting of the valve between an open and a closed disposition during an injection event by controlling a flow of pressurized fuel from the intensifier to the needle valve, the timing controller including an electronically actuated controller valve, the controller valve being in fluid communication with a fuel passage extending between the intensifier and the needle valve, the fuel passage conveying high pressure fuel, the controller chamber is in fluid communication with a fuel reservoir via a fuel refill passage, the controller chamber being refilled with fuel when the controller valve is in a closed disposition, the controller chamber being further in fluid communication with the fuel reservoir via a drain orifice, the drain orifice being open at all times.