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
  • 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
  • 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
  • F02M2200/00—Details of fuel-injection apparatus, not otherwise provided for
  • F02M2200/30—Fuel-injection apparatus having mechanical parts, the movement of which is damped
  • F02M2200/306—Fuel-injection apparatus having mechanical parts, the movement of which is damped using mechanical means

Definitions

• the present invention relates to a fuel injection device for an internal combustion engine intended in particular to equip a motor vehicle.
• the invention relates more particularly to a fuel injection device making it possible to atomize the fuel injected in the form of very fine droplets.
• the fuel injection devices used today on internal combustion engines fitted to motor or road vehicles conventionally operate on the model of a valve, the open or closed state of which is continuously controlled, the dosage of the injected fuel then done directly by the opening time.
• Such injection systems include an electric fuel supply pump which supplies, via a distribution manifold, all of the injectors under a pressure having a constant difference with the pressure prevailing in the intake manifold. through a pressure regulator.
• an electric fuel supply pump which supplies, via a distribution manifold, all of the injectors under a pressure having a constant difference with the pressure prevailing in the intake manifold. through a pressure regulator.
• electromagnet actuating the valve of each injector one controls the beginning and the duration of opening of this one and one then determines a precise flow of fuel for each one of the injectors, thus the quantity of fuel injected depends only on the opening time of the electro-injectors.
• the injectors of the electromagnetically controlled needle type which are the most commonly used, however have limits which hinder the improvement of engine performance, in particular in terms of pollution control.
• the times taken to open or close the needles are still too high, around 1 to 2 ms, which prevents the injection from being distributed correctly over the entire opening time of the valve.
• the minimum opening time which determines the minimum dose of fuel that can be injected, is still too long for certain engine operating points.
• Known needle injectors also have injection holes of relatively large diameters to allow the delivery of the required quantities of fuel for operations at full load and high engine speeds. This arrangement generates fuel jets having drops of large dimensions, which slows down the vaporization of the fuel (and therefore the preparation of the fuel mixture) and is capable of promoting the phenomenon of wall wetting.
• the non-vaporized fuel tends to settle on the walls of the intake duct or the combustion chamber (by direct injection).
• Such a deposit causes metering problems, particularly acute in the transients due to a lack of knowledge of the quantity of fuel which actually enters the combustion chamber. corresponding.
• This wall wetting phenomenon is one of the major causes of the high pollutant emissions during cold engine starts.
• This device is of the type comprising an injector connected to a fuel supply circuit under a suitable pressure, this injector comprising an injection nozzle at the end of which is formed at least one fuel injection orifice and this injector cooperating with means of cyclic vibration controlled by the electronic engine control system so as to cause mechanical oscillations in bending of the injection nozzle, this nozzle injection being adapted to eject a predetermined quantity of fuel at each of its oscillations.
• the object of the present invention is to improve this new type of injection device by proposing a new architecture of injector body which is simpler to produce, in particular in that it is no longer necessary to have a nozzle for injection formed by a plurality of channels of suitable dimensions, joined in a bundle.
• the fuel injection device for internal combustion engine comprises an injector connected to a fuel circuit under a suitable pressure.
• the fuel injection device for an internal combustion engine is characterized in that the injector comprises a cylindrical nozzle supplied with fuel and at the end of which is formed an injection orifice, means for cyclic vibration of the nozzle such as a transducer, said cyclic vibration means being controlled in duration and intensity by the electronic engine control system, and shutter means biased by elastic return means against the end of the nozzle, the elastic elastic return means being formed by a rod passing through the body of the injector to a cavity situated at the opposite end with respect to the injection orifice, the rod cooperating with a mass and damping means housed in the cavity, the vibration of the nozzle and shutter means ensuring the ejection of a predetermined amount of fuel.
• the injector comprises a cylindrical nozzle supplied with fuel and at the end of which is formed an injection orifice, means for cyclic vibration of the nozzle such as a transducer, said cyclic vibration means being controlled in duration and intensity by the electronic engine control system, and shutter means biased by elastic return means against the end of the nozzle, the
• the shutter means are integral with the rod, the flared end of which forms a valve, the rod being mounted axially movable inside said nozzle and being secured by the intermediate damping means with the nozzle.
• the damping means are formed by one of an elastic washer.
• the cavity is formed after the part of the transducer extending behind the injector.
• the transducer comprises a stack of more than two active components.
• the injector can be fixed to the cylinder head by pressing on a seal at the junction where the displacements are minimum.
• the active components of the transducer are formed from a piezoelectric material.
• the active components of the transducer are formed from a magnetostrictive material.
• FIG. 1 represents an overall view, in axial section, of the injection device according to the invention
• FIGS. 2 to 5 schematically explain the operating principle of the injection device according to the invention
• Figure 6 is a partial sectional view of an internal combustion engine cylinder head equipped with a fuel injection device 1 according to the invention.
• FIG. 7 is a view in axial section detailing the distribution of amplitude of vibration along the axis of the injector shown in FIG. 1.
• FIG. 8 is a schematic view of the control circuit of the transducer shown in FIG. 1.
• FIG. 1 the body of the injector object of the present invention has been detailed.
• the body of the inj ector essentially comprises two separate bodies which cooperate with each other.
• the first member is composed of means capable of generating vibrations in a longitudinal mode at ultrasonic frequencies such as a transducer 1, which transducer ends in the lower part by a nozzle of cylindrical shape 3 in which the vibrations coming from the transducer 1.
• the whole of the transducer 1 has an internal cavity 15 intended to be filled with fuel under pressure by means of an axial bore 14 for supplying the fuel coming to connect to a circuit for supplying pressurized fluid 16.
• the cavity 15 opens at the lower end 6 of the nozzle 3 through an injection orifice 5.
• the second member is constituted by a cylindrical rod 4 housed axially movable inside the nozzle 3 and whose frustoconical lower end 7 extends outside the nozzle 3.
• This end 7 forming a valve is adapted to come into contact with the inner surface of the nozzle 3 delimiting the lower opening 5 of the nozzle 3, surface defining a seat for said valve, and thus for closing the fuel injection orifice.
• the other end of the rod 4 is provided with a mass 8 and connected elastically by a washer 9 to the body of the transducer 1. All of the mass 8 and the washer 9 are housed in a cavity 10 formed in the part rear of the transducer 1.
• the mass 8 thus integrated into the injector can have a suitable volume by adjusting the height of this mass without modifying its radius or the geometry of the transducer part 1, which makes it possible to maintain a given radius for the entire inj ector.
• This washer 9 exerts an elastic restoring force tending to apply the end 7 of the rod 4 against the surface surrounding the injection orifice 5 of the nozzle 3.
• the value of the mass 8 and the rigidity of the washer 9 are chosen to form a system having a very long response time in relation to the durations of excitation of the transducer 1.
• the transducer 1 is dimensioned to transmit a maximum of stresses at the junction 12 with the nozzle 3, this maximum of stresses corresponding to a minimum amplitude of vibration for the material.
• the transducer 1 comprises a zone 17 consisting of a stack of active piezoelectric or magnetostrictive components, which, respectively under the application of an electric or magnetic field, deform in thickness.
• This part 17 is sandwiched between two other elements 18 and 19 made up of elastic material.
• prestressing means such as a screw 20.
• the stack of several active components 17 makes it possible to add the thickness deformations generated by each of the rings, the resulting deformation of the total displacement of the stack of rings remaining below the elastic deformation limit of the prestressing means 20.
• the increase in the number of rings in the stack generates a gain in displacement which makes it possible to compensate for the losses of amplification in part 19 of the transducer 1 when the diameter of this part 19 is reduced and there is a single transition zone 12 where the amplification takes place.
• the engine control computer 31 sends two pulses corresponding to the start and end of the injection, during this time an ultrasonic frequency generator 32 sends a wave train (level 5V) at a frequency given at the input of an amplifier 33, which makes it possible to attack the piezoelectric ceramics in alternating voltage
• the assembly composed of the transducer 1 and the nozzle 3 is dimensioned to resonate at the excitation frequency of the active components 17 and to amplify the longitudinal displacements up to the level of the lower end of the nozzle 3.
• the rod 4 initially closing the opening 5 by its end 7 forming a valve, deforms under the impulse which is provided to it when the nozzle 3 starts to oscillate. This deformation is distributed elastically over the entire length of the rod 4 and is reflected at the interface between the rod 4 and the mass 8.
• FIG. 2 describes the relative variation in position between the end 7 of the rod 4 (points Ai) and the end 6 of the nozzle 3 (points Bi) for 3 cycles of oscillation of the resonator assembly.
• Figure 3 illustrates the positions of points Ai and Bi as a function of time.
• the opening of the annular slot 21 is therefore oscillating with a maximum amplitude equal to the maximum difference in amplitude of vibration between the valve 7 and the end 6 as shown in Figure 4.
• the opening frequency of the slot then depends on the excitation frequency chosen for the transducer 1 and the natural frequencies of the rod 4.
• the minimum opening time of the injection device is of the same order as the excitation period applied to the transducer 1, which excitation can take place at a few tens of kilohertz, typically 50 kHz, which allows minimum opening times. of the order of 20 ⁇ s. This makes it possible to deliver micro-quantities of liquid during a reduced period of time compared with more conventional injection devices where the minimum time to operate the opening and closing of the injection nose is rather 300 ⁇ s.
• FIG. 6 there is shown a mode of implantation of an injector according to the invention in an internal combustion engine of a motor vehicle.
• the fuel supply to the engine is of the electronically controlled multipoint type through which each combustion chamber 25 is supplied directly into fuel by at least one fuel injector 1 opening into the chamber.
• the body of the injector is fixed to the cylinder head 24 of the engine at its upper end by means which are not shown, this upper end being moreover connected to a fuel supply pipe.
• the diameter of the nozzle 3 is dimensioned to touch the wall of the well 28 with a spacing corresponding to the thickness of the thermal layer so as to avoid the accumulation of heat towards the end of the nozzle 3.
• the transducer 1 comprises a steel cylinder 18 of diameter 20 mm and height 35 mm comprising in its upper part a housing 10 of height 15 mm for placing the mass 8 and comprising in its lower part a threaded pin 20.
• the threaded axis of the cylinder 18 makes it possible to prestress piezoelectric ceramic rings (external diameter 20 mm, internal diameter 6 mm, thickness 2 mm) between the cylinders 18 and the cylinder 19 having a thread 23.
• the ceramics are arranged with anti-parallel polarizations, electrodes 13 being interposed between each pair of ceramics.
• a titanium rod 4 with a diameter of 2 mm and comprising a conical end 7 with an external diameter of 5 mm is inserted in the axis of the transducer 1.
• An elastic washer 9 has an orifice allowing the rod 4 to pass and is supported on the lower surface of the housing 10.
• a cylindrical mass 8 comprising a thread is screwed onto the other end of the rod 4 comprising a thread.
• the mass 8 is screwed until the desired preload is obtained, enabling the conical end 7 of the rod 4 to be applied to the zone 5 of the nozzle 3, the contact force then being maintained by the elasticity of the 'rod 4 and washer 9 assembly.
• the pre-stress applied allows on the one hand the sealing of the opening 5 of the nozzle 3 when the fluid 16 is supplied with a given pressure and on the other hand the possible take-up of wear in the contact area of the valve 7 with the nozzle 3.
• the value of the mass 8 and the rigidity of the washer 9 are chosen to form a system having a very long response time compared to the durations of excitation of the transducer of the order of 1 to 20 miliseconds at most.
• the material of which the cup is made can be based on polymers having a very high rate of attenuation of elastic deformations in dynamics.
• the mechanical structure is resonant with an oscillation amplitude profile depending on the position on the axis shown in Figure 7.
• the inj ector can be maintained at the junction 12 which is a vibration node.
• the nozzle 3 then transmits the vibrations to its end 6 which deforms with an oscillating movement, which end 6, in turn elastically deforms the rod 4.
• the amplitude of oscillation for a voltage of 60 volts applied to each electrode is close to 20 microns, thus leaving an opening 21 generating a fluid film whose thickness is of the same order (20 microns).
• This fluid film is fragmented by the closing of the opening 21 which occurs after a very short time (every 20 ⁇ s).
• the device thus makes it possible to generate, as required, very fine droplets 22.
• the modulation of the amplitude of the opening 21 makes it possible to modulate the size of the drops and thus the flow rate with response times of the order of 20 ⁇ s.

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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 (3)

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Cited By (1)

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• 1999
  • 1999-11-19 FR FR9914548A patent/FR2801346B1/fr not_active Expired - Fee Related
• 2000
  • 2000-11-17 WO PCT/FR2000/003194 patent/WO2001036813A1/fr active IP Right Grant
  • 2000-11-17 EP EP00981424A patent/EP1248904B1/de not_active Expired - Lifetime
  • 2000-11-17 DE DE60025530T patent/DE60025530T2/de not_active Expired - Lifetime

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