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
  • F02M51/00—Fuel-injection apparatus characterised by being operated electrically
  • F02M51/06—Injectors peculiar thereto with means directly operating the valve needle
  • F02M51/0603—Injectors peculiar thereto with means directly operating the valve needle using piezoelectric or magnetostrictive operating means
• • 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
  • F02M61/00—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00
  • F02M61/04—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00 having valves, e.g. having a plurality of valves in series
  • F02M61/10—Other injectors with elongated valve bodies, i.e. of needle-valve type
• • 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
  • F02M69/00—Low-pressure fuel-injection apparatus ; Apparatus with both continuous and intermittent injection; Apparatus injecting different types of fuel
  • F02M69/04—Injectors peculiar thereto
  • F02M69/041—Injectors peculiar thereto having vibrating means for atomizing the fuel, e.g. with sonic or ultrasonic vibrations
• • 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
  • F02M2200/00—Details of fuel-injection apparatus, not otherwise provided for
  • F02M2200/70—Linkage between actuator and actuated element, e.g. between piezoelectric actuator and needle valve or pump plunger
  • F02M2200/701—Linkage between actuator and actuated element, e.g. between piezoelectric actuator and needle valve or pump plunger mechanical

Definitions

• Device for holding a needle of a fuel injector, and associated fuel injector.
• the present invention relates to the general field of fuel injectors for internal combustion engines of motor vehicles.
• the present invention relates more particularly to a holding device for a needle of a fuel injector which is controlled by ultrasonorcs frequency emissions.
• a holding device for a needle of a fuel injector which is controlled by ultrasonorcs frequency emissions.
• injection systems used operating on the model of a valve which is continuously controls the open or closed state the injected fuel quantity then being directly a function of time of opening of the injectcur.
• Such injection systems include an electric pump fuel supply that supplies, through a manifold, all the injectors.
• an electromagnet may be used to control the valves associated with the injectors.
• the electromagnet actuating the valve of each injector controls the opening time thereof, having previously determined a fuel flow for each of the injectors.
• the amount of fuel injected depends solely on the opening time of the injectors.
• Electromagnetically controlled needle type injectors which are the most commonly used, however, have limits that hinder the improvement of engine performance, especially in terms of pollution control.
• the time taken to open or close the needles are still too high, about I to 2 ras, which prevents the correct distribution of the fuel injection over the entire opening time of the valve.
• the dosage is made only by the duration of opening of the injectcur which is about 0.5 ms to 1 ms.
• the minimum opening time which determines the minimum amount of fuel that can be injected, is still too great for certain operating points of the engine.
• Known needle injectors also have injection ports of relatively large diameter to allow the required quantities of fuel to be discharged for operation at full load and at high engine speeds.
• This arrangement generates fuel jets having drops of large dimensions, which slows the vaporization of the fuel and is able to promote a wetting phenomenon of the walls.
• the non-vaporized fuel tends to be deposited on the walls of the intake duct or the direct injection combustion chamber.
• Such a deposit causes metering problems, particularly acute in the transient phases due to lack of knowledge of the amount of fuel that actually enters the corresponding combustion chamber.
• This wall-wetting phenomenon is one of the important causes of high emissions of pollutants, also with a conventional injector needle, the opening of the needle when the latter begins to leave his seat, forms a liquid bubble that disappears when the needle is completely raised. Fluid flow is regularizing so. This change in the nature of the flow makes it impossible to precisely control the instantaneous flow rate of the injector.
• the device comprises a nozzle supplied with fuel at the end of which is formed an injection orifice closed by the shutter needle.
• the device also comprises means for cyclically vibrating the nozzle and the needle shutter such that a transducer provided with piezoelectric cells and controlled in duration and intensity by the electronic engine control system, to obtain a moving said needle and opening the injection port.
• the device also comprises elastic return means housed in a cavity formed in a portion on the shutter needle.
• FR-A-2 85? 41 8 of the applicant proposes to control the opening of an orifice injecting the fuel injector by generating vibrations.
• the injector comprises means for axially holding the shutter needle which is in particular provided with a nut for adjusting the value of the force exerted by a return spring mounted between the adjustment screen and the injector. .
• this device has the disadvantage of having a relatively large axial size and to understand a relatively complex and expensive structure.
• the present invention therefore aims to overcome these disadvantages.
• the present invention also aims to provide a device for maintaining a needle of a fuel injector which is particularly simple, effective, and easy to assemble.
• the invention therefore relates to a device for holding a needle of a fuel injeetcur, which comprises a support plate and an axial retaining element of the needle of the injector.
• the axial retaining element comprises an attachment portion cooperating with a complementary portion of the pressure plate, and a retaining portion provided with radial protrusions directed inwardly each comprising a contact surface with the needle.
• the device may comprise an elastic return member intended to be mounted between the injector and the support plate.
• the retaining portion comprises axial lugs axially extending the fixing portion, each axial lug being provided, at its lower end, with one of the radial projections.
• the device may advantageously comprise a clamping ring radially surrounding the axial tabs of the retaining portion and mounted to bear against them. The clamping ring can be opened at a point of its circumference.
• the backing plate further comprises a stud having a planar contacting surface with an upper end of the needle.
• the retainer is separate from the backing plate.
• each of these two elements can be particularly simple and economical to manufacture. Indeed, with such a device, it is not necessary to provide at the bearing plate specific forms or bores to maintain the needle.
• the invention also relates to an internal combustion engine fuel injector for a motor vehicle provided with an axially d ⁇ plaçable needle mounted in a body of the injector, and a holding device of the needle comprising a support plate and an axial retaining element of the needle of the injector.
• the axial retaining element comprises an attachment portion cooperating with a complementary portion of the pressure plate, and a retaining portion provided with radial projections directed v ers within each comprising a contact surface with 'needle.
• the inj ectcur éxanche comprises a chamber within which is mounted Ic holding device of the needle and is separated from a fuel circulation circuit to be injected.
• the sealed chamber is filled with a fluid, especially a low pressure fluid.
• an axial space is provided between an end surface of the needle holder and the body of the injector.
• the support plate is shaped to have an acoustic impedance greater than that of the needle.
• the support plate comprises a mass and a density such that it achieves acoustic blocking for the waves propagating in the needle.
• the acoustic compression waves are then reflected in compressio n waves.
• the acoustic compression waves are then reflected in relaxation waves.
• the injector also comprises vibrating means capable of causing mechanical oscillations of the needle.
• FIG. 1 is an axial sectional view of an injector of fuel comprising a device for maintaining a needle of the inj ectur according to a first embodiment of the invention
• FIG. 2 is a perspective view of a retaining element of the device of FIG. 1;
• FIG. 3 is a perspective view of a clamping ring of the device of FIG. 1;
• FIG 4 is an alternative embodiment of the fuel injector of Figure 1; and FIGS 5 and 6 are views in axial section of a fuel injector comprising holding devices of the needle of the injector according to the second and third embodiments of the invention.
• FIG. 1 shows the general structure of a fuel injector for an internal combustion engine of a motor vehicle, designated by the general reference numeral 1 0,
• the injector 1 which has a general shape of revolution about a central axis XX * assumed to be vertical, comprises a body 12 inside which is niontée axialemcnt displaceable a needle 14 of shutter.
• the injector 10 also includes a device 16 for holding the needle 14 in position inside the body 12,
• the body 12 of generally cylindrical outer shape, comprises a bore 1 8 stage arranged along the entire length thereof. Bore 18 is coaxial with the X-X 'axis,
• first stage 1 8a of smaller diameter into which the needle 14 is slidably mounted
• second stage 8b 1 of larger diameter extending axially upwardly the first stage 1 8a
• the body 12 also comprises a closure cover 19 mounted at the upper free end of the second stage 1 8b, and which has an orifice 19a coaxial with the axis XX '.
• the second stage 18a of the bore 1 8 thus delimits with the cpaulcment 14b and with the closing cap 1 9, a chamber 21,
• the injector 1 0 also comprises at its lower end a nozzle 20 of generally tubular shape and extending along the axis X-X ', the inner diameter of the nozzle 20 is substantially equal to that of the first stage 1 8a of the bore 1 8.
• the proximal end 22 of the nozzle 20, in contact with a lower face of the body 12, is intended to be supplied with fuel, and the free or distal end 24 thereof is adapted to allow a fuel injection to the fuel. inside a combustion chamber of the engine (not shown).
• the body 12 of the injector further comprises a substantially radial projection 26 provided with a bore 28 passing through said body 12 and opening at the level of the first stage 18a of the bore 1 8 stage, so as to allow the fuel inlet at the nozzle 20.
• the projection 26 is here located axially close to the underside of the body 12,
• the shutter needle 14 comprises a cylindrical portion 14a, of smaller diameter on the order of a few tenths of a millimeter to the diameter of the first stage 1 8a of the bore 18, so as to create a axial annular passage for the fuel between the first stage 18a of the bore 18 and the needle 1 4 as well as between the nozzle 20 and said needle,
• the cylindrical portion 14a is extended to an upper end by a shoulder 14b shaped to precisely fit with the first stage 1 8a of the bore 1 8 and thereby limit any possible fuel leakage to Ic second stage 18b, L the upper end of the shoulder 14b protrudes into the second stage 18b.
• the needle 14 comprises at its lower free end 32 axially projecting head able to come into contact with the distal end 24. The distal end 24 thus form seat the needle 14.
• the fuel can not be injected into the combustion chamber
• the device 16 is mounted inside the second stage 18b of large diameter of the bore 1 8, the device 16 comprises in particular a support plate 40, an elastic member return 42 mounted between the body 12 of the injector 10 and the support plate 40, and an axial retaining element 44 of the needle 14 mounted on said plate 40,
• the support plate 40 is mounted near the upper end of the second stage 1 8b of the bore 1 8, II has a relatively small axial dimension, and comprises a cylindrical protuberance 46 of reduced diameter. relative to that of the plate 40, it extends axially downward along the axis XX 'from a lower surface 48 of the plate 40.
• the surface 48 forms a stop surface for an upper end of the body elastic spring 42, made here in the form of a spring.
• the lower end of the elastic member 42 bears against a radial connecting surface 50 of the body 12 formed between the second stage 1 8b and the first stage 1 8a of the bore 18.
• the elastic return member 42 exerts an axial force on the support plate 40 so as to keep it away from the connecting surface 50, the axial force is directed axially upwards.
• the axial retaining element 44 made in one piece, the latter comprises an annular fixing portion 52 mounted to bear against the abutment surface 48.
• the fixing portion 52 extends axially from a lower end by axial tabs 54.
• the fixing portion 52 comprises a threaded bore 52a cooperating with a corresponding thread 46a formed on the outer surface of the protuberance 46.
• the axial dimension of the portion Fixing plate 52 is here equal to that of protrusion 46. Its radial dimension is smaller than the radial dimension of support plate 40 so as to leave free, at the abutment surface 48, an annular surface for support of the upper end of the elastic member 42 of return.
• the lugs 54 here four in number, are circumferentially uniformly distributed over the fixing portion 52. Each lug 54 comprises a first portion 54a inclined outwardly extending which is extended at its lower free end by a second portion 54b axial. The circumferential dimension of the tabs 54 is here greater at their implanturc than at their free end.
• each of the tabs 54 is extended at its lower end by a projection 56.
• the projections 56 extend here radially towards the interior and have a rounded or spherical general shape. They each bear against a contact zone formed at an upper end of the shoulder 14b of the needle 14.
• each projection 56 comprises a contact surface with the needle 1 4.
• Said contact zones are made here in the form of an annular groove 60.
• the relative radii of curvature of the projections 56 and the groove 60 define the type of locking performed. If the protrusions 56 have a greater radius of curvature than the groove 60, the support plate 40 is integral with the end of the needle 14. Otherwise, the support plate 40 is secured to the support plate. needle 14 is made only in an axial direction. The projections 56 cooperate with the groove 60 so as to allow axial retention of the needle 14 in its closed position. In other words, the axial lugs 54 and the projections 56 of the element 44 constitute a retaining portion for the needle 14.
• the device 1 6 also comprises an annular clamping ring 62 radially surrounding the tabs 54 and coming into contact against the outer surface thereof. It has here an axial dimension slightly lower than that of the legs 54.
• the clamping ring 62 is open at a point of its circumference (FIG. 3), to facilitate its mounting on the tabs 54.
• the needle 14 is thus maintained in its closed position, safely.
• the injector In order to avoid axial separation of the clamping ring 62 with respect to the retaining element 44, that may comprise, at the outer surfaces of the second portions 54b of the lugs 54, protrusions directed radially outwardly engageable with grooves of corresponding shape formed the bore of the ring 62. This limits a possible axial displacement downwards of the ring 62.
• the injector also comprises, at the level thereof, a stack 70 of piezoelectric active components, which under the application of an electric field, deform in thickness.
• the injector 1 0 In order to fix the fitting 70 on the nozzle 20, the latter comprises, at the end of its distal end 24, a radial flange 72, here made integral with said nozzle, and against which the stack 70 comes to rest.
• the injector 1 0 further includes a nut 74 provided with an elastic prestressing system which is mounted on the nozzle 20 so as to sandwich the stack 70 between the abutment member 72 and said nut 74.
• These elements 72 and 74 are conventionally used for fuel injeetcurs controlled by ultrasonic frequency emission.
• the stack 70 consisting of a plurality of piezoelectric active components makes it possible to add the thickness deformations generated by each of them, the resultant deformation of the total displacement of the stack 70 remaining below the limit of elastic deformation of the nut. 74.
• the electronic engine control system In order to allow the stack 70 to vibrate, the electronic engine control system is used. In this regard, it sends two pulses corresponding to the beginning and the end of the fuel injection. Between these two impulses, he generates a train of waves at a predetermined frequency so as to supply alternating voltage to the stack 70. and thereby cause its deformation.
• the nozzle 20 and the needle 14 are dimensioned to resonate at the excitation frequency of the stack 70.
• the shoulder 14b of the needle 14 here comprises a plurality of grooves.
• each projection 56 is associated a groove 82.
• the injector 10 comprises an outgoing needle. It is readily conceivable that it is also possible, without departing from the scope of the invention, to provide, as illustrated in FIG. 5, a mjector 10 which comprises a so-called incoming head 84 located inside the inside. of the nozzle 20, the distal end 24 of the nozzle 20 being shaped accordingly.
• the elastic return member 42 is disposed between the closure cap 76 of the injector 10 and the support plate 40.
• the elastic member 42 exerts recall here an axial force on plate 40 Ic bearing so as to bring it closer to the connecting surface 50.
• the "axial force is here directed downwardly.
• FIG. 6 differs from that of FIG. 1 in that the support plate 40 comprises a relatively large axial dimension.
• the support plate 40 is shaped so as to have a mass sufficient to present acoustic conditions of quasi-locking the end of the needle 14.
• the support plate 40 is able to create a acoustic impedance breaking so as to symmetrically return the compression waves.
• the support plate 40 also comprises a cylindrical stud 86 which extends axially downwards the protuberance 46.
• the stud 86 is centered on the axis XX '. It comprises, at its lower end, a plane contact surface mounted in abutment against a planar upper surface of the shoulder 14b of the needle 14.
• the stud 86 and the needle 14 are thus conformed so as to obtain a surface contact. between these two elements.
• the chamber 21 contains low pressure fluid. Indeed, a fluid promotes the propagation of waves. This propagation is also ensured by the existence of the plane contact surfaces of the stud 86 and needle 14, which can also be rectified in this respect.
• the chamber 21 is separate or separate from the high pressure fuel circulation circuit, which allows two fluids of different natures to be used.
• the chamber 21 is sealed.
• the orifice 19a may be used.
• the support plate 40, the protuberance 46 and the stud 86 are made in one piece.
• an axial space (not referenced) is provided between an upper end 49 surface of the tray 40 to support the needle holder and the cover body 19 closing the injcctcur.
• a first axial length L between a lower surface of the closure cap 19 and the distal end 24 of the nozzle 20 is greater than a second axial length L 1 defined by the axial distance between the upper surface 49 of the nozzle.
• the axial space has an axial dimension ⁇ which corresponds to the geometric tolerances of the elements of the injector 10 and to any thermal variations.
• the axial space is filled with the fluid present inside the sealed chamber. A fluid film is thus interposed between the surface
• the axial dimension ⁇ of the axial space is as small as possible so as to obtain a strong acoustic coupling.

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

Applications Claiming Priority (2)

Publications (2)

Family

ID=38093163

Family Applications (1)

Country Status (5)

Family Cites Families (4)

• 2006
  • 2006-10-09 FR FR0654168A patent/FR2906848B1/fr not_active Expired - Fee Related
• 2007
  • 2007-09-26 WO PCT/FR2007/052013 patent/WO2008043929A2/fr not_active Ceased
  • 2007-09-26 EP EP07823858A patent/EP2078158B1/de not_active Ceased
  • 2007-09-26 AT AT07823858T patent/ATE471452T1/de not_active IP Right Cessation
  • 2007-09-26 DE DE602007007233T patent/DE602007007233D1/de active Active

Non-Patent Citations (1)

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