FR2884876A1 - FIXING DEVICE FOR MOUNTING AN INJECTOR HOLDER ON AN INTERNAL COMBUSTION ENGINE AND INTERNAL COMBUSTION ENGINE COMPRISING SUCH A DEVICE - Google Patents

Abstract

The invention concerns a fixing device for mounting an injector-holder (2), source of vibrations, on an internal combustion engine, capable of receiving and transmitting the vibrations, by means of a fixing element (1). The fixing device comprises means for compensating (B) the vibrations produced in the form of a first element (M) forming a sliding weight and at least a second element (R1) forming a spring linking the sliding weight (M) to the fixing element (1).

Description

The invention relates to a fastening device for mounting a carrier

  injector, a source of vibration, on an internal combustion engine, capable of receiving and transmitting the vibrations, by means of an element of

  attachment, and an internal combustion engine comprising such a device.

  During the design of a motor vehicle, it has long been tradition to provide means to prevent the generation of vibration or, at least, to provide means for damping. A typical example is the vibration dampers used for the suspension of the engine block in the chassis of the vehicle. For this purpose, for example, rubber blocks are used.

  Recent approaches to reduce the noise that a motor vehicle in general and a particular powertrain generate are increasingly directed to the very sources of noise. Indeed, the most effective approaches to reduce noise and vibration, are to act closer to the source, or even directly on the cause of noise when possible.

  One of the most pronounced noises of a power train in a motor vehicle is the noise generated by the injectors, especially in compression ignition engines.

  The injectors are intended to be mounted, to perform their function, on an engine block provided with at least one combustion chamber in which such an injector must inject a fuel.

  Injectors are a source of vibration for two reasons.

  Firstly, the injectors are a source of vibration because of the moving parts which are activated for the subsequent preparation of the fuel portions intended to be injected into the combustion chamber or chambers according to the engine speed. These parts are generally solicited in translatory and oscillatory movements.

  The injectors are then a source of vibration because of pressure changes that occur continuously during the preparation and injection of the fuel portions. Each change of pressure, and in particular each discharge of pressure, generates vibrations. These vibrations propagate in the form of a directly audible acoustic radiation. Other vibrations from the injectors are caused by changes in pressure that cause contractions of the body and parts of the injectors.

  The noise of the injectors transmitted and radiated by an internal combustion engine is related on the one hand to an exciter phenomenon of the piezoelectric actuator for diesel injectors and needle shock for gasoline injectors. On the other hand, the noise of the injectors is related to the dynamic response of the injector holder to this excitation. This vibratory behavior makes the injector holder emissive on the airway and exciter, on the solid track, for the top of the engine which can in turn radiate.

  Controlling the quantities of fuel injected imposes needle movements, therefore the actuator, faster and faster to meet the objectives of limiting pollution and to limit the noise of combustion or to limit consumption.

  The dual nature of injectors as a source of vibration has already been recognized in the state of the art and has given rise to solutions favoring one or rather the other of the two phenomena mentioned above. However, these solutions concerned each time the injector itself or the use of an additional part during assembly of the injector. Thus, for example, US-A-6 382 532 teaches the use of viscoelastic spacers introduced at different locations between the injector and the part of the engine block into which the injector is inserted.

  However, because of the local temperatures encountered, for example, in the lower part of an injector or in contact with the cylinder head, the use of complementary parts, for example viscoelastic spacers, is not always possible.

  The object of the invention is to propose a solution that makes it possible to damp vibrations and noise generated by an injector intended to be mounted on an internal combustion engine.

  The object of the invention is achieved with a fixing device for mounting an injector holder, source of vibration, on an internal combustion engine, capable of receiving and transmitting the vibrations, with the aid of a fastening element.

  According to the invention, the fixing device comprises vibration compensation means in the form of a first element forming a moving mass and a set of second elements forming springs connecting the moving mass to the fixing element. .

  The present invention makes it possible to reduce the vibrations inherent in the operation of an injector by reducing the vibratory amplitudes of the injector fixing system at the traction / compression frequencies of the injector holder and thus to reduce the level of noise radiated by the injector. the injector carrier by air means that the vibratory excitation imposed on the upper part of the engine by the solidary track.

  The use of the present invention makes it possible to reduce the impulse character of the noise, to which the injector contributes in a strong manner, and thus makes it possible to contribute to the improvement of the acoustic coloration of the internal combustion engines.

  As such, the present invention also relates to the following features, taken alone or in any technically possible combination: the compensation means are shaped to damp axial vibrations; the second elements are formed by helical springs; the second elements are formed by Belleville springs; the second elements are formed by elastomeric springs.

  The object of the present invention is also achieved with an internal combustion engine, injection, comprising at least one fuel injector mounted on a cylinder head of the engine, the engine comprising a fixing device described above.

  The present invention therefore deals with the dynamic response of the system, to obtain arrangements to better control the acoustic radiation and the excitation that it imposes on the upper part of the engine.

  The device of the invention is based on the observation that the eigenmode, partly responsible for the noise of the injectors, is associated with a deformation of the "traction-compression" type of the injector holder in the longitudinal axis of the injectors, generating as a result of significant displacement of the fastening system in the same axis. This clean mode is generally located around 4000 Hz. It is strongly solicited by excitations from the actuator or the needle of the injector.

  The fixing device according to the invention incorporates the principle of axial drummer conventionally used as vibration damper, applied here to the fixing system of the injector holder. Fixing can be done by a flange or a fork. Subsequently, the invention will be described for the attachment of an injector holder with a fork.

  Other types of attachment will be the subject of alternative embodiments of the invention.

  The principle of the drummer is adapted as far as possible, on the maximum range of the fork and according to the possibilities of implantation.

  The axial drummer principle corresponding to the principle of using vibration compensation means, such compensation means are preferably arranged or implanted near the bearing points of the fork on the injector holder. These vibration compensation means are simple mass-spring systems whose natural frequency 2z. \ / K / M is to wedge on the traction / compression frequency of the injector holder. It is necessary to ensure perfect mobility of the mass with respect to the range.

  The spring system can be realized by the use of coil springs, placed on either side of the mass, or by the use of Belleville springs or by the use of an elastomer.

  When it is not possible to implant the moving mass and the spring system close to the support points of the fork on the carrier injector, all of the moving mass and the spring system can be implanted by example, near the points of support on the porteinjecteur.

  It is also possible to use several mixer systems, each of them being keyed to another frequency. This arrangement allows to amortize several eigen modes.

  When, instead of a fork, a flange or a double flange is used to attach an injector holder to the internal combustion engine, the maximum deflection zones of the flange are determined, if necessary according to the possibilities of implementation of the system. In case of difficulty of implantation on the maximum deflection areas, it is also possible to insert the movable mass assembly and spring in a less restrictive position.

  When using a three-point flange, this fastening element can receive three sets of moving mass and a spring, near the bearing points of the flange on the injector holder, with the possibility of wedging each of them at a different frequency. It is the same for the case of a double flange mentioned above.

  The mass-spring system described above can be replaced by a single piece having appropriate dimensions and whose stiffness and clean mass lead to a natural frequency 2 / K / M which is stalled on the pulling frequency / compression of the door -injector.

  Fixing device for mounting, by means of a fastening element, such as a fork, a flange or any other suitable element, of an injector holder, source of vibrations, on an internal combustion engine, capable of to receive and transmit the vibrations, uses the principle of the axial drummer to a degree of freedom. This makes it possible to cancel the displacement of a structure, in resonance or in forced response to a given frequency. The fastening device according to the invention therefore comprises the fastening element itself and the injector, the assembly forming a system of mass M1 and stiffness K1, subjected to a force F (w) = Fo.cos ( wt). The single beater is an additional system M2 mass and stiffness -K2, additional to the fastening system, as shown in Figure 1 of the accompanying drawings.

  The system formed by the fixing element and the system formed by the beater each have a natural frequency 1 w, defined according to the equation 1VKI / Mi = 2z for the element of 1 w2 fixation and, similarly, VK2 / M2 = for the 2z 2z drummer. The respective displacements of the two systems are indicated in FIG. 1 by the vectors μ1 and u2.

  The sizing of the drummer consists of choosing M2 and K2 to cancel the displacement U1, for a chosen frequency wo / 2n (in general wo = w1).

  The equations of the motion of this new system are written in the form: "Mi 0 '\ (ü (w) (KI + K2 - K2 vui (w)" F (w) + _ 0 M2) vüz (CO) ) K2 K2) u2 (w) 0 We look for U1 and U2 in the form uX = UX. cos (w, t). He comes then.

  / Ui _ Fo (K2 - w2 M2v (Ki + K2 - w2 M1) (K2 - w2 M2) -K22 K2 So, to cancel the displacement U1 at the frequency wo / 2n on this simple system, to choose M2 and K2 5 such that: In the case of the injector holder, it is therefore appropriate, as explained in the description of the invention, to wedge 1 / 2z.JK2 / M2 on the natural frequency of traction-compression (about 4000 Hz on the known injectors), penalizing the noise.

  When the type of fastener used for mounting the injector holders involves several drummers each of which is to be stalled on another natural frequency, there is superposition of the systems described above.

  The device of the invention makes it possible to reduce the vibratory amplitudes of the fastening system at the traction-compression frequencies of each of the injector holders and thus to reduce the level of noise radiated by the injector nozzle (s) by air, as well as the vibratory excitation imposed on the upper part of the motor by solidary way.

  Other features and advantages of the present invention will emerge from the following description of an embodiment of the invention. The description is made with reference to the accompanying drawings in which: - Figure 1 shows the principle of the axial mixer to a degree of freedom applied to an oscillating mass - Figure 2 shows the implementation of a drummer in a range for the mounting of an injector holder, - figure 3 shows the implementations of drummers in a symmetrical flange intended for the mounting of an injector holder, - figure 4 assembles the drummer implantations in a double flange intended for mounting a Injector holder, - Figure 5 shows the implementations of drummers in a three-point flange for mounting an injector holder, and - Figure 6 shows a single piece capable of vibrating and intended to replace the mass system and spring.

  FIG. 1 represents the principle of the present invention according to which a fixing element having mass M1 and stiffness K1, which is subjected to a force F (w), is provided with a single beater having mass M2 and stiffness K2 whose oscillatory or vibratory behavior is superimposed on that of the fixing element. The two elements, the fixing element and the beater, are therefore connected to each other additionally, and each of these two systems is subjected to displacements of the same orientation represented by the arrows ul and u2.

  Figure 2 shows the implementation of a drummer on a fastener according to one embodiment of the invention. FIG. 2 shows a fork 1 fixing an injector holder 2 on an internal combustion engine 3. The fork 1 is fixed on the engine 3 by means of a bolt 4 passing through an orifice 5 made in the fork 1 .

  At the two ends 6 and 7 of the fork 1, ends intended to bear on the injector holder 2 are drummers B, one of which is shown schematically at the top of Figure 2. This drummer comprises a mass M and two springs R1, R2 whose upper spring R1 has a stiffness K / n and the lower spring R2 has a stiffness (n-1) x K / n.

  Figure 3 shows schematically a flange 11 in an axial view and a side view. In the axial view, one sees on the one hand two orifices 12, 13 for fixing the flange and on the other hand two locations 14, 15 for the implantation of drummers. The flange in side view shows the implantation of one of the beaters B. FIG. 4 schematically shows a double flange 21 in a perspective view with two injector holders 22, 23. The double flange 21 is fixed on a motor internal combustion 3A using a screw 24 passing through a hole 25 formed in the flange. The double flange 21 comprises six beater implantations B, that is to say three for each injector holder. Implantations are indicated by circles drawn in solid lines or broken lines.

  FIG. 5 schematically shows a three-point flange 31 in perspective view with an injector holder 32. The three-point flange 31 is attached to an internal combustion engine 3B by means of three screws 33 to 35 passing through holes in the flange, but hidden in Figure 5 by washers placed under the heads of the screws. The three-point flange 31 comprises three implementations of drummers B. The implantations are indicated by circles.

  Figure 6 shows a variant of the fastener according to the invention according to which a single piece 41 able to vibrate is intended to replace the mass and spring system. A beater B is implanted in one of two ends 42, 43 of the single piece 41. In the embodiment shown in FIG. 6, the beater B is implanted at the end 42.

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Claims (7)

  1. Fastening device for mounting an injector holder (2), vibration source, on an internal combustion engine, capable of receiving and transmitting the vibrations, by means of a fastening element (1 ), characterized in that it comprises means (B) for compensating vibrations in the form of a first element (M) forming a mobile mass and at least one second element (R1) forming a spring linking the moving mass (M) to the fastening element (1).   2. Fastening device according to claim 1, characterized in that the compensation means (B) are shaped to damp axial vibrations.   3. Fastening device according to claim 1 or 2, characterized in that the second elements (R1, R2) are formed by helical springs.   4. Fastening device according to claim 1 or 2, characterized in that the second elements (R1, R2) are formed by Belleville springs.   5. Fastening device according to claim 1 or 2, characterized in that the second elements (R1, R2) are formed by elastomeric springs.   6. Fastening device according to claim 1, characterized in that the first element (M) forming a moving mass and a second single element (Rl) are formed by a single piece capable of vibrating.   7. Internal combustion engine, injection, comprising at least one fuel injector mounted on a cylinder head of the engine, characterized in that it comprises a fixing device according to any one of claims 1 to 6.