Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M47/00—Fuel-injection apparatus operated cyclically with fuel-injection valves actuated by fluid pressure
  • F02M47/02—Fuel-injection apparatus operated cyclically with fuel-injection valves actuated by fluid pressure of accumulator-injector type, i.e. having fuel pressure of accumulator tending to open, and fuel pressure in other chamber tending to close, injection valves and having means for periodically releasing that closing pressure
  • F02M47/027—Electrically actuated valves draining the chamber to release the closing pressure
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M45/00—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship
  • F02M45/12—Fuel-injection apparatus characterised by having a cyclic delivery of specific time/pressure or time/quantity relationship providing a continuous cyclic delivery with variable pressure
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M63/00—Other fuel-injection apparatus having pertinent characteristics not provided for in groups F02M39/00 - F02M57/00 or F02M67/00; Details, component parts, or accessories of fuel-injection apparatus, not provided for in, or of interest apart from, the apparatus of groups F02M39/00 - F02M61/00 or F02M67/00; Combination of fuel pump with other devices, e.g. lubricating oil pump
  • F02M63/0012—Valves
  • F02M63/0031—Valves characterized by the type of valves, e.g. special valve member details, valve seat details, valve housing details
  • F02M63/004—Sliding valves, e.g. spool valves, i.e. whereby the closing member has a sliding movement along a seat for opening and closing

Definitions

• the present invention relates to a fuel injector suitable for use in an internal combustion engine.
• the invention relates to the control of a valve needle in a fuel injector.
• the valve needle operates in a bi-polar manner.
• a hydraulic force imbalance is created that rapidly drives the needle in one direction or the other until movement of the needle is arrested.
• Opening movement of the valve needle is arrested at a full lift position by an abutment or lift stop (embodied as a plate 25 in the injector of Figure 1 ). Closing movement of the valve needle is arrested when the tip engages with the valve seat.
• FIG. 1 of the accompanying drawings which has already been referred to above, is a part-sectional view of a known fuel injector.
• the present invention will now be described, by way of example only, with reference to the remaining drawings in which like reference numerals are used for like parts and in which:
• Figure 8(a) is a part-sectional view of part of a fuel injector according to a second embodiment of the present invention
• Figure 8(b) is an end view of a slave piston of the fuel injector of Figure 8(a);
• the nozzle body 102 is provided with a nozzle bore 108, which receives high-pressure fuel from a fuel supply passage 105 provided in the injector body 104, via an annular gallery 107 at the uppermost end of the nozzle bore 108.
• a valve needle 1 10 is slidably received within the nozzle bore 108.
• Each of the fuel outlets 1 12, 1 14 passes through the wall of the nozzle body 102, so as to provide radial and axial flow paths to allow fuel to flow from a delivery chamber 186, defined by the nozzle bore 108, through the nozzle body 102 and into the combustion chamber 1 18, in use.
• a lower portion of the valve needle 1 10 comprises a shaft 109 having a tip 1 1 1 .
• the tip 1 1 1 comprises a frusto-conical valve member 1 20.
• the valve member 1 20 is of complementary shape to a valve seat 122 provided in the nozzle bore 102.
• a drain chamber 174 is provided.
• the drain chamber 174 has a smaller diameter than the control piston 148 and the control bore 144.
• the lowermost end or tip of the control piston 148 comprises a frusto-conical valve element 170 arranged to seat on a seating region 172 of complementary shape.
• the seating region 172 is formed as a shoulder in the slave piston 130 where the drain chamber 174 meets the control bore 144.
• the control piston 148 is tubular to define a drain passage 176 that runs axially through the bore of the control piston 148.
• the lower end of the drain passage 176 communicates with the drain chamber 174, while the upper end of the drain passage 176 communicates with a fuel drain at low pressure (not shown).
• a collar on the control piston stem 149 is provided so that, when the first actuator is energised, the collar couples to the armature of the first actuator to move the control piston 148 from a lower end-stop position to a well-defined intermediate position. Then, on energisation of the second actuator, the collar decouples from the armature of the first actuator and the control piston 148 is drawn from the intermediate position to an upper end-stop position by the action of the second actuator alone.
• EP 09166712.1 the contents of which are incorporated herein by reference, for more details of such an actuator arrangement.
• control chamber 152 is connected neither to the high-pressure fuel supply in the internal gallery 160, nor to the drain chamber 174.
• fuel neither flows into nor out of the control chamber 152, and the fuel pressure in the control chamber 152 remains constant.
• the volume of the control chamber 152 is essentially fixed, and the slave piston 130 (and hence the valve needle 1 10) cannot move with respect to the control chamber block 106.
• the injector 100 if the injector 100 is operating in the third mode of operation with the control piston in a starting position, the valve needle 1 10 will be held in a static intermediate position. If the control piston 148 is then displaced downwards from the starting position, the injector 100 will revert to the first mode of operation: the upper control port 166 will open so as to allow fuel to flow into the control chamber 1 52, thereby causing downwards movement of the slave piston 130 and hence the valve needle 1 10 as described above until the upper control port 166 is closed once again by the piston member 162 and the valve needle 1 10 adopts a new static intermediate position displaced downwardly from its original intermediate position.
• the amount of fuel that is discharged to drain corresponds to the volume displaced during upward movement of the slave piston 130 in the second mode of operation.
• the amount of fuel that is discharged to drain during operation of the injector is much lower than for a conventional fuel injector having a hydraulic servo mechanism such as that shown in Figure 1 , in which high-pressure fuel is discharged constantly to drain while the valve needle is lifted.
• a fuel injector 200 according to second embodiment of the invention will now be described with reference to Figures 8(a), 8(b) and 9.
• a nozzle path orifice 284 formed as a flat on the guide portion 285 of the valve needle 210 adjacent to the lower guide portion 282 of the nozzle bore 208, provides a restricted flow path for fuel between the gallery 207 and a delivery chamber 286 formed by the nozzle bore 208 downstream of the lower guide portion 282.
• the control chamber block 206 comprises a control chamber 252 that receives the upper end 246 of the slave piston.
• the slave piston 230 includes a blind control bore 244. A lower end of a control piston 148 is received within the control bore 244, and the upper end of the control piston 148 passes up through the control chamber 252 and the control chamber block 206 to cooperate with an actuator arrangement (not shown).
• the control piston 148 is as described above with reference to the first embodiment of the invention.
• the slave piston 230 is provided with a side drilling 256 to allow fuel to flow from the gallery 207 to an internal chamber 260 defined by the necked portion 158 of the control piston 148.
• grooves such as the upper and lower grooves 362a, 362b on the piston member 362 of the injector 300 of the third embodiment of the invention could also be provided on the piston members of the first and second embodiments of the invention, thereby to balance the radial pressure on the control piston and reduce friction between the control piston and the walls of the control bore.
• control piston is a close sliding fit within the control bore of the slave piston in the vicinity of the control ports, so as to avoid leakage from the ports when the ports are closed.
• a larger clearance can be provided between the control piston stem and the control piston bore, above the necked portion of the control piston since, between injection events, the control chamber and the internal gallery are at approximately the same fuel pressure, thereby obviating the effect of leakage in that area.
• the present invention finds application in fuel injectors having other arrangements at the tip of the injector.
• the present invention is suitable for substantially any design of injector tip where it is necessary, or desirable, to provide one or more intermediate valve needle lift positions, and/or to control the velocity of the valve needle.
• the present invention could be used to control the valve needle position in a so-called variable orifice nozzle, such as that described in the applicant's European Patent Publication EP-B-1626173.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Fuel-Injection Apparatus (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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Citations (8)

• 2009
  • 2009-11-04 EP EP09175036A patent/EP2320061A1/de not_active Withdrawn
• 2010
  • 2010-10-05 WO PCT/EP2010/064853 patent/WO2011054613A1/en not_active Ceased

Patent Citations (8)

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