EP0279710A1 - Exhaust system for a six-cylinder V-type engine - Google Patents

Exhaust system for a six-cylinder V-type engine Download PDF

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Publication number
EP0279710A1
EP0279710A1 EP88400042A EP88400042A EP0279710A1 EP 0279710 A1 EP0279710 A1 EP 0279710A1 EP 88400042 A EP88400042 A EP 88400042A EP 88400042 A EP88400042 A EP 88400042A EP 0279710 A1 EP0279710 A1 EP 0279710A1
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EP
European Patent Office
Prior art keywords
branch
exhaust
branches
engine
pipe
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP88400042A
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German (de)
French (fr)
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EP0279710B1 (en
Inventor
Jean Gratadour
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Automobiles Peugeot SA
Automobiles Citroen SA
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Automobiles Peugeot SA
Automobiles Citroen SA
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Publication of EP0279710A1 publication Critical patent/EP0279710A1/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
    • F01N13/08—Other arrangements or adaptations of exhaust conduits
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N1/00—Silencing apparatus characterised by method of silencing
    • F01N1/06—Silencing apparatus characterised by method of silencing by using interference effect
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B75/00—Other engines
    • F02B75/16—Engines characterised by number of cylinders, e.g. single-cylinder engines
    • F02B75/18—Multi-cylinder engines
    • F02B75/22—Multi-cylinder engines with cylinders in V, fan, or star arrangement

Definitions

  • the invention relates to an exhaust device of a six-cylinder V-shaped engine arranged transversely at the front of a motor vehicle.
  • V6 engines that is to say engines comprising six cylinders in a V arrangement
  • these six cylinders are distributed in two rows of three cylinders, one of which is disposed at the front, with respect to the second row or back row.
  • the exhaust device of such a transverse V6 engine comprises a front branch constituted by a pipe connected to the pipes or to the exhaust manifold of the three cylinders of the front row and a rear branch formed by a pipe connected to the pipes or to the manifold. exhaust from the three rear row cylinders.
  • the front branch must pass under the engine either to be joined to the rear branch and constitute a single branch, or to travel over a certain length in parallel with the rear branch before constituting a single branch.
  • the front and rear branches and the single branch ensuring their junction are directed in the longitudinal direction of the vehicle and towards the rear and the single branch is connected to the exhaust line of the vehicle.
  • the front branch of the exhaust therefore has a length greater than the rear branch, which causes certain drawbacks with regard to the attenuation of certain harmonics of the acoustic excitation of the exhaust.
  • the acoustic excitation in the two branches has the same amplitude and the operation of the V6 engine is such that, for certain harmonics, the acoustic waves are in phase opposition in the two front and rear branches, so that the acoustic excitation is canceled at the entry of the single branch ensuring the junction of the front and rear branches.
  • the level of the 1.5 N harmonic becomes very high when the difference in length between the front and rear conduits exceeds 400 mm. Generally, this difference in length is close to 500mm in the usual arrangements of transverse V6 engines.
  • the object of the invention is therefore to propose an exhaust device for a six-cylinder V-shaped engine arranged transversely at the front of a motor vehicle, comprising a front branch which collects the gases from a first row of three cylinders located towards the front and a rear branch which collects the gases of a second row of three cylinders situated towards the rear with respect to the first row, the front and rear branches being constituted by pipes which join at their opposite end to the engine, in a single branch which is connected to the exhaust pipe of the vehicle, this exhaust device making it possible to attenuate the low frequency harmonics of the acoustic excitation of the exhaust and in particular the harmonic of frequency 1.5 N, without requiring, inside the engine compartment, a special arrangement of the pipes of the front and rear branches.
  • the front and rear branches of the exhaust have lengths which differ by at least 400 mm and the single branch is in communication with the input of a device to inter ferences located outside the engine compartment in the exhaust line and comprising at least two branches which constitute by their union a branch at the entry of the interference device and a branch at the outlet and which produce a separation of the gas flow d in at least two streams and a phase shift of the low frequency acoustic waves flowing in one of the branches relative to the waves flowing in the other branch, so that the waves corresponding to the 1.5 N harmonic are attenuated by interference at the output of the interference device.
  • FIG 1 we see a V6 engine placed transversely in the engine compartment of a vehicle occupying its front part.
  • This engine 1 comprises a front row 1a and a rear row 1b each comprising three cylinders, the cylinders of row 1a being arranged angularly and in this specific case at 90 ° relative to the cylinders of row 1b.
  • the three cylinders in row 1a have a common exhaust manifold 2a and the three cylinders in the rear row 1b, a common exhaust manifold 2b.
  • the engine exhaust device 1 comprises, inside the engine compartment, a front branch 3a connected to the manifold 2a and a rear branch 3b connected to the manifold 2b.
  • the branch 3a must pass under the engine 1 to join the branch 3b, at the rear of the engine, these two branches being directed in parallel towards the rear of the motor (arrows 4).
  • the length of the front leg 3a of the exhaust is much greater than the length of the branch 3b, these lengths respectively Li and L 2 corresponding for one to the length of the piping between the manifold 2a and the junction point 8 and, for the other, the length of the piping between the manifold 2b and the junction point 8.
  • the difference L i - L 2 is much greater than the limit from which the level of the 1.5 N harmonic becomes very high.
  • the interference device 12 comprises two branches 14 and 15 connected to the single branch 10 of the exhaust at a branch 16.
  • the two branches 14 and 15 meet at a junction point 18 upstream of the exhaust pipe 11 of the vehicle.
  • the branch 14 is constituted by a single pipe.
  • the branch 15 is constituted by the succession of a pipe 19, of a capacity 20 constituting a transverse silencer and of a second pipe 21.
  • the first pipe 19 makes it possible to join the branch 16 into which the single branch 10 opens, to the muffler 20.
  • the pipe 21 makes it possible to join the muffler 20 to the branch 18 upstream of the exhaust pipe 11.
  • This device 12 achieves on the one hand the separation of the gas flow originating from the single branch 10 into two flows circulating respectively in the branch 14 and in the branch 15.
  • This device 12 also constitutes an attenuator for the low frequency harmonics of the acoustic excitation in the exhaust device, the branch 15 constituting a phase shifter and the branch 14 ensuring only a small phase shift.
  • the silencer 20 is placed at a distance d1 from the branch 16 which corresponds substantially to the length of the pipe 19 of the branch 15 and at a distance d2 from the outlet branch 18 of the interference device which corresponds substantially to the length of piping 21.
  • the piping 14 has a long length corresponding to the length d1 + d2.
  • a device such as the device 12 constitutes a very energetic attenuator in a certain range of low frequencies and in particular for the harmonic of frequency 1.5 N of the motor.
  • a person skilled in the art knows how to determine the lengths of the branches 14 and 15, the lengths d1 and d2, the volume 20 and the diameters of the pipes of the branches 14 and 15 so that the acoustic flows at the outlet of the device 12 cancel each other out and that the gas flow can pass with a minimum pressure drop.
  • FIG 2 there is shown schematically a branch which may constitute the outlet branch of an interference device.
  • This branch comprises a first branch 22, a second branch 23 and a output branch 24.
  • dl , d2 and s be the Fresnel vectors representing, for the harmonic considered, the flows leaving the branches 22 and 23 and entering the output branch 24.
  • An interference device therefore assumes the existence of two branches between which a flow is separated to obtain two gaseous and acoustic flows which are then combined, at the outlet of branches of the interference device.
  • the presence of the silencer 20 and the arrangement of the pipes ensure a phase shift greater than ⁇ from a certain frequency f0.
  • the section and the length of the first branch 14 are chosen so that the acoustic flows leaving the two branches 14 and 15 are substantially equal in amplitude for a frequency f slightly greater than f0.
  • the branch 14 produces only a small phase shift.
  • the interference effect is maximum for the frequency f and extends over a certain frequency range around f.
  • the device is designed so that the frequency f corresponds to 1.5 N, N corresponding to the normal engine speed.
  • FIGS. 4a, 4b and 4c there are shown three types of interference devices capable of being used for the attenuation of the low frequency components, in the vicinity of the 1.5 N harmonic, in an exhaust device d 'a transverse V6 engine as shown in Figure 3.
  • the interference device comprises a first branch 24 which is a simple pipe and a second branch 25a, 25b or 25c on which is inserted a silencer 26a, 26b and 26c, respectively.
  • the silencer 26a is a simple cavity into which the end portions of an inlet pipe 27 and an outlet pipe 28 penetrate.
  • the silencer 26b is a capacity transversed by a pipe 29 comprising, in its part passing through the capacity 26b, orifices 30 carefully calibrated and arranged along the length and the circumference of the pipe 29.
  • the silencer 26c is a capacity shared in two chambers 26e and 26f by means of a wall 26d into which the ends of an inlet pipe 31 and an outlet pipe 32 respectively emerge and which are connected by an intermediate pipe 33.
  • the lengths of the branches 24 and 25 are large enough to allow the processing of acoustic waves at low frequency, that is to say having large wavelengths.
  • phase shift introduced by the asymmetry of the two branches of the device 12 must take a sufficient value so that an interference phenomenon is obtained which makes it possible to attenuate the 1.5 N harmonic, N corresponding to the normal regime of the engine in revolutions per minute.
  • the entire interference device will always be placed outside the engine compartment and associated with a part of the vehicle in which the space requirement of the interference device is not a critical element. .
  • the implementation of the invention supposes the separation of the flow of exhaust gases into at least two gas and acoustic flows, a different treatment of the two gas and acoustic flows in long branches introducing a phase shift of the low frequency waves. and a meeting of the two streams at a time when the phase shifts and amplitudes for the frequencies considered allow significant attenuation.
  • FIGS. 5A and 5B show two types of interference devices known for their use in attenuating the high frequencies corresponding to short wavelengths. These devices use short piping lengths and do not make it possible to produce a significant phase shift of the acoustic waves in both branches, for low frequencies, that is to say long wavelengths .
  • the interference device is preferably arranged just upstream of the vehicle exhaust but it is also possible to move this device more or less by using a connecting pipe of varying length.
  • the piping joining the interference device to the front and rear branches of the exhaust may itself have a variable length, depending on the characteristics of the front and rear branches of the exhaust and the interference device.
  • the front and rear branches can include devices such as catalysts which do not change anything with regard to the problem of the 1.5 N harmonic and its resolution by the device according to the invention.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Exhaust Silencers (AREA)

Abstract

1. Exhaust device for a transverse, six cylinder V engine at the front of a motor vehicle, which has a front branch (3a) collecting the gases from a first row of three cylinders (1a) located at the front and a rear branch (3b) collecting the gases of a second row (1b) of three cylinders located at the rear with respect to the first row (1a), the front and rear branches (3a, 3b) being constituted by pipes joining at their end opposite to the engine (1) to form a single branch (10) which is connected to the vehicle exhaust tank (11), characterized in that the front and rear branches (3a, 3b) of the exhaust placed between engine (1) and junction point (8) with the single branch (10) have lengths differing by at least 400 mm and the single branch (10) is linked with the intake of an interference device (12) positioned outside the engine compartment (5) in the exhaust line and having at least two branches (14, 15) which, by their joining, constitute a junction (16) at the intake of the interference device (12) and a junction (18) at the outlet and which produce a subdivision of the exhaust gas flow into at least two flows and a phase shift of the low frequency sound waves flowing in one of the branches (15) with respect to the waves flowing in the other branch (14), so that the waves corresponding to the 1.5 N harmonic, N being r.p.m., are attenuated by interference at the outlet (18) from the interference device.

Description

L'invention concerne un dispositif d'échappement d'un moteur à six cylindres en V disposé transversalement à l'avant d'un véhicule automobile.The invention relates to an exhaust device of a six-cylinder V-shaped engine arranged transversely at the front of a motor vehicle.

Dans les véhicules récents, il existe une certaine tendance à monter le groupe moteur à l'avant et en position transversale. Dans le cas des moteurs V6 c'est-à-dire des moteurs comportant six cylindres dans une disposition en V, ces six cylindres se répartissent en deux rangées de trois cylindres dont l'une est disposée à l'avant, par rapport à la seconde rangée ou rangée arrière. Le dispositif d'échappement d'un tel moteur V6 transversal comporte une branche avant constituée par une tuyauterie reliée aux tubulures ou au collecteur d'échappement des trois cylindres de la rangée avant et une branche arrière constituée par une tuyauterie reliée aux tubulures ou au collecteur d'échappement des trois cylindres de la rangée arrière. La branche avant doit passer sous le moteur soit pour être jointe à la branche arrière et constituer une branche unique, soit pour cheminer sur une certaine longueur en parallèle avec la branche arrière avant de constituer une branche unique. Dans les deux cas, les branches avant et arrière et la branche unique assurant leur jonction sont dirigées suivant la direction longitudinale du véhicule et vers l'arrière et la branche unique est reliée à la ligne d'échappement du véhicule.In recent vehicles, there is a certain tendency to mount the power unit at the front and in a transverse position. In the case of V6 engines, that is to say engines comprising six cylinders in a V arrangement, these six cylinders are distributed in two rows of three cylinders, one of which is disposed at the front, with respect to the second row or back row. The exhaust device of such a transverse V6 engine comprises a front branch constituted by a pipe connected to the pipes or to the exhaust manifold of the three cylinders of the front row and a rear branch formed by a pipe connected to the pipes or to the manifold. exhaust from the three rear row cylinders. The front branch must pass under the engine either to be joined to the rear branch and constitute a single branch, or to travel over a certain length in parallel with the rear branch before constituting a single branch. In both cases, the front and rear branches and the single branch ensuring their junction are directed in the longitudinal direction of the vehicle and towards the rear and the single branch is connected to the exhaust line of the vehicle.

La branche avant de l'échappement présente donc une longueur supérieure à la branche arrière, ce qui occasionne certains inconvénients en ce qui concerne l'atténuation de certaines harmoniques de l'excitation acoustique de l'échappement. En effet, dans le cas où les deux branches de l'échappement sont de longueurs égales, l'excitation acoustique dans les deux branches a la même amplitude et le fonctionnement du moteur V6 est tel que, pour certaines harmoniques, les ondes acoustiques sont en opposition de phase dans les deux branches avant et arrière, si bien que l'excitation acoustique s'annule à l'entrée de la branche unique assurant la jonction des branches avant et arrière. Il en résulte en particulier, dans ce cas, une compensation naturelle de l'harmonique de fréquence 1,5 N de l'excitation acoustique de l'échappement, N étant le régime ou nombre de tours par minute du moteur. Dans le cas où les longueurs des deux branches ne sont pas identiques, les ondes acoustiques subissent dans la branche la plus longue un déphasage supplémentaire a qui fait que certaines harmoniques (comme 1,5 N) ne se compensent plus naturellement. Le problème posé par l'harmonique 1,5 N spécifique aux moteurs V6 à disposition transversale et sa résolution en utilisant des conduits avant et arrière entièrement symétriques sont bien connus de l'homme de métier.The front branch of the exhaust therefore has a length greater than the rear branch, which causes certain drawbacks with regard to the attenuation of certain harmonics of the acoustic excitation of the exhaust. Indeed, in the case where the two branches of the exhaust are of equal lengths, the acoustic excitation in the two branches has the same amplitude and the operation of the V6 engine is such that, for certain harmonics, the acoustic waves are in phase opposition in the two front and rear branches, so that the acoustic excitation is canceled at the entry of the single branch ensuring the junction of the front and rear branches. This results in particular, in this case, a natural compensation for the 1.5 N frequency harmonic of the acoustic excitation of the exhaust, N being the engine speed or number of revolutions per minute. In the case where the lengths of the two branches are not identical, the acoustic waves undergo in the longest branch an additional phase shift a which means that certain harmonics (such as 1.5 N) no longer compensate naturally. The problem posed by the 1.5 N harmonic specific to V6 engines with transverse arrangement and its resolution using entirely symmetrical front and rear conduits are well known to those skilled in the art.

Le déphasage supplémentaire a par rapport à la situation en opposition de phases des excitations acoustiques dans les deux rangées de cylindres peut être fourni par un calcul simplifié et donné par l'expression, pour l'harmonique 1,5 N :

Figure imgb0001
où N est le régime du moteur, 11 la longueur de la branche avant de l'échappement, 12 la longueur de la branche arrière, et C la vitesse du son.The additional phase shift a compared to the situation in opposite phases of the acoustic excitations in the two rows of cylinders can be provided by a simplified calculation and given by the expression, for the harmonic 1,5 N:
Figure imgb0001
 where N is the engine speed, 1 1 the length of the front branch of the exhaust, 1 2 the length of the rear branch, and C the speed of sound.

Il peut résulter de ce déphasage un niveau de l'harmonique 1,5 N du bruit de bouche de l'échappement très élevé, si la différence 12 - 11 est supé rieure à une certaine limite, si l'excitation acoustique est forte ou si la vitesse du son est relativement réduite.It can result from this phase shift a level of the harmonic 1.5 N of the exhaust noise from the exhaust very high, if the difference 1 2 - 1 1 is greater than a certain limit, if the acoustic excitation is strong or if the speed of sound is relatively reduced.

Le niveau de l'harmonique 1,5 N devient très élevé lorsque la différence de longueur entre les conduits avant et arrière dépasse 400 mm. Généralement, cette différence de longueur est voisine de 500mm dans les dispositions habituelles de moteurs V6 transversaux.The level of the 1.5 N harmonic becomes very high when the difference in length between the front and rear conduits exceeds 400 mm. Generally, this difference in length is close to 500mm in the usual arrangements of transverse V6 engines.

On a cherché à résoudre ce problème en diminuant le plus possible la différence de longueur entre la branche avant et la branche arrière, ce qui peut être obtenu en rallongeant la branche arrière et/ou en diminuant la longueur de la branche avant. On a ainsi proposé de faire suivre un cheminement tortueux à la branche arrière de l'échappement avant sa jonction avec la branche avant. Cependant une telle disposition présente des inconvénients venant du fait qu'on dispose de très peu de place dans le compartiment moteur et que l'écoulement des gaz d'échappement n'est pas satisfaisant dans la partie tortueuse de la branche arrière. Elle conduit également à éloigner les catalyseurs du moteur, ce qui nuit à leur efficacité.We sought to solve this problem by reducing as much as possible the difference in length between the front branch and the rear branch, which can be obtained by lengthening the rear branch and / or by reducing the length of the front branch. It has thus been proposed to follow a tortuous path to the rear branch of the exhaust before it joins the front branch. However, such an arrangement has drawbacks from the fact that there is very little space in the engine compartment and that the flow of exhaust gases is not satisfactory in the tortuous part of the rear branch. It also leads to the catalysts being moved away from the engine, which affects their efficiency.

Le but de l'invention est donc de proposer un dispositif d'échappement d'un moteur à six cylindres en V disposé transversalement à l'avant d'un véhicule automobile, comportant une branche avant qui collecte les gaz d'une première rangée de trois cylindres située vers l'avant et une branche arrière qui collecte les gaz d'une seconde rangée de trois cylindres située vers l'arrière par rapport à la première rangée, les branches avant et arrière étant constituées par des tuyauteries qui se rejoignent à leur extrémité opposée au moteur, en une branche unique qui est raccordée au pot d'échappement du véhicule, ce dispositif d'échappement permettant d'atténuer les harmoniques de basse fréquence de l'excitation acoustique de l'échappement et en particulier l'harmonique de fréquence 1,5 N, sans nécessiter, à l'intérieur du compartiment moteur, une disposition particulière des tuyauteries des branches avant et arrière.The object of the invention is therefore to propose an exhaust device for a six-cylinder V-shaped engine arranged transversely at the front of a motor vehicle, comprising a front branch which collects the gases from a first row of three cylinders located towards the front and a rear branch which collects the gases of a second row of three cylinders situated towards the rear with respect to the first row, the front and rear branches being constituted by pipes which join at their opposite end to the engine, in a single branch which is connected to the exhaust pipe of the vehicle, this exhaust device making it possible to attenuate the low frequency harmonics of the acoustic excitation of the exhaust and in particular the harmonic of frequency 1.5 N, without requiring, inside the engine compartment, a special arrangement of the pipes of the front and rear branches.

Dans ce but, les branches avant et arrière de l'échappement ont des longueurs qui diffèrent d'au moins 400 mm et la branche unique est en communication avec l'entrée d'un dispositif à interférences situé en dehors du compartiment moteur dans la ligne d'échappement et comportant au moins deux branches qui constituent par leur réunion un embranchement à l'entrée du dispositif à interférences et un embranchement à la sortie et qui produisent une séparation du flux de gaz d'échappement en au moins deux flux et un déphasage des ondes acoustiques à basse fréquence circulant dans une des branches par rapport aux ondes circulant dans l'autre branche, de façon que les ondes correspondant à l'harmonique 1,5 N soient atténuées par interférence à la sortie du dispositif à interférences.For this purpose, the front and rear branches of the exhaust have lengths which differ by at least 400 mm and the single branch is in communication with the input of a device to inter ferences located outside the engine compartment in the exhaust line and comprising at least two branches which constitute by their union a branch at the entry of the interference device and a branch at the outlet and which produce a separation of the gas flow d in at least two streams and a phase shift of the low frequency acoustic waves flowing in one of the branches relative to the waves flowing in the other branch, so that the waves corresponding to the 1.5 N harmonic are attenuated by interference at the output of the interference device.

Afin de bien faire comprendre l'invention, on va décrire, à titre d'exemples non limitatifs, plusieurs modes de réalisation d'un dispositif d'échappement suivant l'invention.

  • La figure 1 est une vue simplifiée en élévation dans la direction transversale d'un moteur V6 et des branches avant et arrière de son dispositif d'échappement.
  • La figure 2 est une vue schématique d'un embranchement et les figures 2a et 2b sont des représentations vectorielles des débits acoustiques, à la sortie de cet embranchement, sans et avec interférences.
  • La figure 3 est une vue schématique en élévation d'un dispositif d'échappement suivant l'invention.
  • Les figures 4a, 4b et 4c sont des vues schématiques de dispositifs à interférences correspondant à trois modes de réalisation préférentiels de l'invention.
  • Les figures 5A et 5B sont des représentations schématiques de dispositifs à interférences connus utilisés dans le cas de l'atténuation d'ondes acoustiques à fréquence élevée (supérieure à 200 Hz).
In order to clearly understand the invention, several embodiments of an exhaust device according to the invention will be described, by way of nonlimiting examples.
  • Figure 1 is a simplified elevational view in the transverse direction of a V6 engine and the front and rear legs of its exhaust device.
  • FIG. 2 is a schematic view of a branch and FIGS. 2a and 2b are vector representations of the acoustic flows, at the outlet of this branch, without and with interference.
  • Figure 3 is a schematic elevational view of an exhaust device according to the invention.
  • Figures 4a, 4b and 4c are schematic views of interference devices corresponding to three preferred embodiments of the invention.
  • FIGS. 5A and 5B are schematic representations of known interference devices used in the case of attenuation of acoustic waves at high frequency (greater than 200 Hz).

Sur la figure 1, on voit un moteur V6 placé transversalement dans le compartiment moteur d'un véhicule occupant sa partie avant. Ce moteur 1 comporte une rangée avant 1a et une rangée arrière 1 b comportant chacune trois cylindres, les cylindres de la rangée 1a étant disposés angulairement et dans ce cas précis à 90° par rapport aux cylindres de la rangée 1b.In Figure 1, we see a V6 engine placed transversely in the engine compartment of a vehicle occupying its front part. This engine 1 comprises a front row 1a and a rear row 1b each comprising three cylinders, the cylinders of row 1a being arranged angularly and in this specific case at 90 ° relative to the cylinders of row 1b.

Les trois cylindres de la rangée 1a comportent un collecteur d'échappement commun 2a et les trois cylindres de la rangée arrière 1b, un collecteur d'échappement commun 2b. Le dispositif d'échappement du moteur 1 comporte, à l'intérieur du compartiment moteur, une branche avant 3a reliée au collecteur 2a et une branche arrière 3b reliée au collecteur 2b. La branche 3a doit passer sous le moteur 1 pour rejoindre la branche 3b, à l'arrière du moteur, ces deux branches étant dirigées en parallèle vers l'arrière du moeur (flèches 4).The three cylinders in row 1a have a common exhaust manifold 2a and the three cylinders in the rear row 1b, a common exhaust manifold 2b. The engine exhaust device 1 comprises, inside the engine compartment, a front branch 3a connected to the manifold 2a and a rear branch 3b connected to the manifold 2b. The branch 3a must pass under the engine 1 to join the branch 3b, at the rear of the engine, these two branches being directed in parallel towards the rear of the motor (arrows 4).

Sur la figure 3, on voit que le moteur 1 et ses tuyauteries d'échappement 3a et 3b sont disposées à l'intérieur du compartiment moteur 5 du véhicule dont on a représenté en pointillés, de façon schémati que, la paroi de séparation arrière 7. Les branches avant 3a et arrière 3b de l'échappement se rejoignent au niveau d'un embranchement 8, pour constituer une branche unique 10 qui est située à l'extérieur du compartiment moteur 5 et qui est reliée au pot d'échappement 11 du véhicule, par l'intermédiaire de tuyauteries et d'un ensemble 12 constituant un dispositif à interférences.In Figure 3, we see that the engine 1 and its exhaust pipes 3a and 3b are arranged inside the engine compartment 5 of the vehicle which is shown in dotted lines, schematically that, the rear partition wall 7 The front 3a and rear 3b branches of the exhaust meet at a branch 8, to form a single branch 10 which is located outside the engine compartment 5 and which is connected to the exhaust 11 of the vehicle, by means of pipes and an assembly 12 constituting an interference device.

On voit que la longueur de la branche avant 3a de l'échappement est beaucoup plus grande que la longueur de la branche 3b, ces longueurs respectivement Li et L2 correspondant pour l'une à la longueur de la tuyauterie comprise entre le collecteur 2a et le point de jonction 8 et, pour l'autre, à la longueur de la tuyauterie entre le collecteur 2b et le point de jonction 8. La différence Li - L2, en général voisine de 800 mm, est nettement supérieure à la limite à partir de laquelle le niveau de l'harmonique 1,5 N devient très élevé.We see that the length of the front leg 3a of the exhaust is much greater than the length of the branch 3b, these lengths respectively Li and L 2 corresponding for one to the length of the piping between the manifold 2a and the junction point 8 and, for the other, the length of the piping between the manifold 2b and the junction point 8. The difference L i - L 2 , generally close to 800 mm, is much greater than the limit from which the level of the 1.5 N harmonic becomes very high.

Le dispositif à interférences 12 comporte deux branches 14 et 15 reliées à la branche unique 10 de l'échappement au niveau d'un embranchement 16. Les deux branches 14 et 15 se rejoignent en un point de jonction 18 en amont du pot d'échappement 11 du véhicule.The interference device 12 comprises two branches 14 and 15 connected to the single branch 10 of the exhaust at a branch 16. The two branches 14 and 15 meet at a junction point 18 upstream of the exhaust pipe 11 of the vehicle.

La branche 14 est consitutée par un tuyau unique.The branch 14 is constituted by a single pipe.

La branche 15 est constituée par la succession d'un tuyau 19, d'une capacité 20 constituant un silencieux transversal et d'un second tuyau 21. Le premier tuyau 19 permet de joindre l'embranchement 16 dans lequel débouche la branche unique 10, au silencieux 20. Le tuyau 21 permet de joindre le silencieux 20 à l'embranchement 18 en amont du pot d'échappement 11.The branch 15 is constituted by the succession of a pipe 19, of a capacity 20 constituting a transverse silencer and of a second pipe 21. The first pipe 19 makes it possible to join the branch 16 into which the single branch 10 opens, to the muffler 20. The pipe 21 makes it possible to join the muffler 20 to the branch 18 upstream of the exhaust pipe 11.

Ce dispositif 12 réalise d'une part la séparation du flux gazeux provenant de la branche unique 10 en deux flux circulant respectivement dans la branche 14 et dans la branche 15.This device 12 achieves on the one hand the separation of the gas flow originating from the single branch 10 into two flows circulating respectively in the branch 14 and in the branch 15.

Ce dispositif 12 constitue également un atténuateur pour les harmoniques à basse fréquence de l'excitation acoustique dans le dispositif d'échappement, la branche 15 constituant un déphaseur et la branche 14 n'assurant qu'un faible déphasage.This device 12 also constitutes an attenuator for the low frequency harmonics of the acoustic excitation in the exhaust device, the branch 15 constituting a phase shifter and the branch 14 ensuring only a small phase shift.

Le silencieux 20 est placé à une distance d1 de l'embranchement 16 qui correspond sensiblement à la longueur du tuyau 19 de la branche 15 et à une distance d2 de l'embranchement de sortie 18 du dispositif à interférences qui correspond sensiblement à la longueur de la tuyauterie 21.The silencer 20 is placed at a distance d1 from the branch 16 which corresponds substantially to the length of the pipe 19 of the branch 15 and at a distance d2 from the outlet branch 18 of the interference device which corresponds substantially to the length of piping 21.

La tuyauterie 14 présente une grande longueur correspondant à la longueur d1 + d2.The piping 14 has a long length corresponding to the length d1 + d2.

Un dispositif tel que le dispositif 12 constitue un atténuateur très énergique dans une certaine plage de basses fréquences et en particulier pour l'harmonique de fréquence 1,5 N du moteur. L'homme du métier sait déterminer les longueurs des branches 14 et 15, les longueurs d1 et d2, le volume 20 et les diamètres des tuyaux des branches 14 et 15 de façon que les débits acoustiques à la sortie du dispositif 12 s'annulent et que le flux gazeux puisse passer avec un minimum de perte de charge.A device such as the device 12 constitutes a very energetic attenuator in a certain range of low frequencies and in particular for the harmonic of frequency 1.5 N of the motor. A person skilled in the art knows how to determine the lengths of the branches 14 and 15, the lengths d1 and d2, the volume 20 and the diameters of the pipes of the branches 14 and 15 so that the acoustic flows at the outlet of the device 12 cancel each other out and that the gas flow can pass with a minimum pressure drop.

On va se reporter aux figures 2, 2a et 2b pour expliquer le fonctionnement d'un dispositif à interférences.We will refer to Figures 2, 2a and 2b to explain the operation of an interference device.

Sur la figure 2, on a représenté de façon schématique un embranchement pouvant constituer l'embranchement de sortie d'un dispositif à interférences. Cet embranchement comporte une première branche 22, une seconde branche 23 et une branche de sortie 24.In Figure 2, there is shown schematically a branch which may constitute the outlet branch of an interference device. This branch comprises a first branch 22, a second branch 23 and a output branch 24.

Soit dl , d2 et s , les vecteurs de Fresnel représentant, pour l'harmonique considérée,les débits sortant des branches 22 et 23 et entrant dans la branche de sortie 24.Let dl , d2 and s be the Fresnel vectors representing, for the harmonic considered, the flows leaving the branches 22 and 23 and entering the output branch 24.

Soit des sections des conduits 22, 23 et 24 telles que d + d2 ≃ ds, on observe un phénomène d'interférences si :

  • Figure imgb0002
    ou
  • Figure imgb0003
Let sections of conduits 22, 23 and 24 be such that d + d2 ≃ ds, we observe an interference phenomenon if:
  • Figure imgb0002
     or
  • Figure imgb0003

Sur la figure 2a, on a représenté les vecteurs

Figure imgb0004
, d2 et ds tel qu'aucune des relations 1 et 2 ne soit vérifiée. Dans ce cas, il n'y a pas interférence.In Figure 2a, the vectors are shown
Figure imgb0004
, d 2 and d s such that none of relations 1 and 2 is verified. In this case, there is no interference.

Sur la fiqure 2b en revanche, on a représenté les vecteurs

Figure imgb0004
,
Figure imgb0006
et
Figure imgb0007
de façon que la relation 1 soit vérifiée. Dans ce cas, il y a interférence.On the fiqure 2b on the other hand, one represented the vectors
Figure imgb0004
,
Figure imgb0006
and
Figure imgb0007
so that relation 1 is checked. In this case, there is interference.

Un dispositif à interférences suppose donc l'existence de deux branches entre lesquelles on sépare un flux pour obtenir deux flux gazeux et acoustiques qui sont ensuite réunis, à la sortie de branches du dispositif à interférence.An interference device therefore assumes the existence of two branches between which a flow is separated to obtain two gaseous and acoustic flows which are then combined, at the outlet of branches of the interference device.

Sur chacune des branches les flux gazeux et acoustiques subissent des traitements différents qui produisent un déphasage différent des ondes acoustiques.On each of the branches the gas and acoustic flows undergo different treatments which produce a different phase shift of the acoustic waves.

En réglant les débits acoustiques et le déphase des deux flux l'un par rapport à l'autre à la sortie des branches, on peut atténuer fortement ou même annuler certaines composantes de fréquence de l'excitation acoustique.By adjusting the acoustic flow rates and the phase shift of the two flows relative to each other at the outlet of the branches, it is possible to strongly attenuate or even cancel certain frequency components of the acoustic excitation.

Dans le cas du dispositif 12 représenté sur la figure 3 qui est équivalent à un système masse- ressort-masse en mécanique des solides, la présence du silencieux 20 et la disposition des tuyauteries assurent un déphasage supérieur à π à partir d'une certaine fréquence f0.In the case of the device 12 shown in FIG. 3 which is equivalent to a mass-spring-mass system in solid mechanics, the presence of the silencer 20 and the arrangement of the pipes ensure a phase shift greater than π from a certain frequency f0.

La section et la longueur de la première branche 14 sont choisies de façon que les débits acoustiques sortant des deux branches 14 et 15 soient sensiblement égaux en amplitude pour une fréquence f un peu supérieure à f0. La branche 14 ne produit qu'un déphasage faible.The section and the length of the first branch 14 are chosen so that the acoustic flows leaving the two branches 14 and 15 are substantially equal in amplitude for a frequency f slightly greater than f0. The branch 14 produces only a small phase shift.

L'effet d'interférence est maximum pour la fréquence f et s'étend sur une certaine plage de fréquence autour de f. Le dispositif est conçu pour que la fréquence f corresponde à 1,5 N, N correspondant au régime normal du moteur.The interference effect is maximum for the frequency f and extends over a certain frequency range around f. The device is designed so that the frequency f corresponds to 1.5 N, N corresponding to the normal engine speed.

Sur les figures 4a, 4b et 4c, on a représenté trois types de dispositifs à interférences susceptibles d'être utilisés pour l'atténuation des composantes basse fréquence, au voisinage de l'harmonique 1,5 N, dans un dispositif d'échappement d'un moteur V6 transversal tel que représenté sur la figure 3.In FIGS. 4a, 4b and 4c, there are shown three types of interference devices capable of being used for the attenuation of the low frequency components, in the vicinity of the 1.5 N harmonic, in an exhaust device d 'a transverse V6 engine as shown in Figure 3.

Sur les figures 4a, 4b, 4c, le dispositif à interférences comporte une première branche 24 qui est un simple tuyau et une seconde branche 25a, 25b ou 25c sur laquelle est intercalé un silencieux 26a, 26b et 26c, respectivement.In FIGS. 4a, 4b, 4c, the interference device comprises a first branch 24 which is a simple pipe and a second branch 25a, 25b or 25c on which is inserted a silencer 26a, 26b and 26c, respectively.

Le silencieux 26a est une simple cavité dans laquelle pénètrent les parties d'extrémité d'un tuyau d'entrée 27 et d'un tuyau de sortie 28.The silencer 26a is a simple cavity into which the end portions of an inlet pipe 27 and an outlet pipe 28 penetrate.

Le silencieux 26b est une capacité transversée par un tuyau 29 comportant, dans sa partie traversant la capacité 26b, des orifices 30 soigneusement calibrés et disposés suivant la longueur et la circonférence du tuyau 29.The silencer 26b is a capacity transversed by a pipe 29 comprising, in its part passing through the capacity 26b, orifices 30 carefully calibrated and arranged along the length and the circumference of the pipe 29.

Le silencieux 26c est une capacité partagée en deux chambres 26e et 26f au moyen d'une paroi 26d dans lesquelles débouchent les extrémités respectivement d'un tuyau d'entrée 31 et d'un tuyau de sortie 32 et qui sont reliées par un tuyau intermédiaire 33.The silencer 26c is a capacity shared in two chambers 26e and 26f by means of a wall 26d into which the ends of an inlet pipe 31 and an outlet pipe 32 respectively emerge and which are connected by an intermediate pipe 33.

Dans tous les cas, les longueurs des branches 24 et 25 sont suffisamment grandes pour permettre le traitement d'ondes acoustiques à basse fréquence, c'est-à-dire ayant des longueurs d'onde importantes.In all cases, the lengths of the branches 24 and 25 are large enough to allow the processing of acoustic waves at low frequency, that is to say having large wavelengths.

Dans tous les cas, le déphasage introduit par la dissymétrie des deux branches du dispositif 12 doit prendre une valeur suffisante pour qu'on obtienne un phénomène d'interférences permettant d'atténuer l'harmonique 1,5 N, N correspondant au régime normal du moteur en tours par minute.In all cases, the phase shift introduced by the asymmetry of the two branches of the device 12 must take a sufficient value so that an interference phenomenon is obtained which makes it possible to attenuate the 1.5 N harmonic, N corresponding to the normal regime of the engine in revolutions per minute.

Il est bien évident également que l'ensemble du dispositif à interférences sera toujours disposé à l'extérieur du compartiment moteur et associé à une partie du véhicule dans laquelle l'encombrement d'ailleurs réduit du dispositif à interférences n'est pas un élément critique.It is also obvious that the entire interference device will always be placed outside the engine compartment and associated with a part of the vehicle in which the space requirement of the interference device is not a critical element. .

La mise en oeuvre de l'invention suppose la séparation du flux des gaz d'échappement en au moins deux flux gazeux et acoustiques, un traitement différent des deux flux gazeux et acoustiques dans des branches de grande longueur introduisant un déphasage des ondes à basse fréquence et une réunion des deux flux à un moment où les déphasages et amplitudes pour les fréquences conidérées permettent une atténuation importante.The implementation of the invention supposes the separation of the flow of exhaust gases into at least two gas and acoustic flows, a different treatment of the two gas and acoustic flows in long branches introducing a phase shift of the low frequency waves. and a meeting of the two streams at a time when the phase shifts and amplitudes for the frequencies considered allow significant attenuation.

Sur les figures 5A et 5B, on a représenté deux types de dispositifs à interférences connus pour leur utilisation dans l'atténuation des fréquences élevées correspondant à de faibles longueurs d'onde. Ces dispositifs mettent en oeuvre des longueurs de tuyauterie faibles et ne permettent pas de produire un déphasage important des ondes acoustiques dans l'une et l'autre branches, pour les basses fréquences, c'est-à-dire les grandes longueurs d'onde.FIGS. 5A and 5B show two types of interference devices known for their use in attenuating the high frequencies corresponding to short wavelengths. These devices use short piping lengths and do not make it possible to produce a significant phase shift of the acoustic waves in both branches, for low frequencies, that is to say long wavelengths .

L'invention ne se limite pas aux modes de réalisation qui ont été décrits.The invention is not limited to the embodiments which have been described.

C'est ainsi qu'on peut imaginer l'utilisation de dispositifs quelconques pour introduire une dissymétrie importante entre les deux branches du dispositif à interférences.This is how we can imagine the use of any devices to introduce significant asymmetry between the two branches of the interference device.

Le dispositif à interférences est disposé de préférence juste en amont du pot d'échappement du véhicule mais il est également possible d'éloigner plus ou moins ce dispositif en utilisant une tuyauterie de liaison de plus ou moins grande longueur. La tuyauterie joignant le dispositif à interférences aux branches avant et arrière de l'échappement peut avoir elle-même une longueur variable, en fonction des caractéristiques des branches avant et arrière de l'échappement et du dispositif à interférences.The interference device is preferably arranged just upstream of the vehicle exhaust but it is also possible to move this device more or less by using a connecting pipe of varying length. The piping joining the interference device to the front and rear branches of the exhaust may itself have a variable length, depending on the characteristics of the front and rear branches of the exhaust and the interference device.

Les branches avant et arrière peuvent comporter des dispositifs tels que des catalyseurs qui ne changent rien en ce qui concerne le problème de l'harmonique 1,5 N et de sa résolution par le dispostif selon l'invention.The front and rear branches can include devices such as catalysts which do not change anything with regard to the problem of the 1.5 N harmonic and its resolution by the device according to the invention.

Claims (5)

1.- Dispositif d'échappement d'un moteur à six cylindres en V disposé transversalement à l'avant d'un véhicule automobile, comportant une branche avant (3a) qui collecte les gaz d'une première rangée de trois cylindres (1a) situés vers l'avant et une branche arrière (3b) qui collecte les gaz d'une seconde rangée (1b) de trois cylindres situés vers l'arrière par rapport à la première rangée (1a), les branches avant et arrière (3a, 3b) étant constituées par des tuyauteries se rejoignant à leur extrémité opposée au moteur (1) en une branche unique (10) qui est raccordée au pot d'échappement (11) du véhicule, caractérisé par le fait que les branches avant et arrière (3a, 3b) de l'échappement intercalées entre le moteur (1) et le point de jonction (8) avec la branche unique (10) ont des longueurs qui diffèrent d'au moins 400 mm et que la branche unique (10) est en communication avec l'entrée d'un dispositif à interférences (12) situé en dehors du compartiment moteur (5) dans la ligne d'échappement et comportant au moins deux branches (14, 15) qui constituent, par leur réunion, un embranchement (16) à l'entrée du dispositif à interférences (12) et un embranchement (18) à la sortie, et qui produisent une séparation du flux de gaz d'échappement en au moins deux flux et un déphasage des ondes acoustiques à basse fréquence circulant dans une des branches (15) par rapport aux ondes circulant dans l'autre branche (14), de façon que les ondes correspondant à l'harmonique 1,5 N, N étant le régime normal du moteur, soient atténuées par interférences, à la sortie (18) du dispositif à interférences.1.- Exhaust device of a six-cylinder V-shaped engine arranged transversely at the front of a motor vehicle, comprising a front branch (3a) which collects the gases from a first row of three cylinders (1a) situated towards the front and a rear branch (3b) which collects the gases of a second row (1b) of three cylinders situated towards the rear with respect to the first row (1a), the front and rear branches (3a, 3b) being constituted by pipes joining at their opposite end to the engine (1) in a single branch (10) which is connected to the exhaust pipe (11) of the vehicle, characterized in that the front and rear branches ( 3a, 3b) of the exhaust interposed between the engine (1) and the junction point (8) with the single branch (10) have lengths which differ by at least 400 mm and that the single branch (10) is in communication with the input of an interference device (12) located outside the engine compartment (5) in the ech line ppement and comprising at least two branches (14, 15) which constitute, by their union, a branch (16) at the entry of the interference device (12) and a branch (18) at the exit, and which produce a separation of the exhaust gas flow in at least two flows and a phase shift of the low frequency acoustic waves circulating in one of the branches (15) relative to the waves circulating in the other branch (14), so that the waves corresponding to the 1.5 N harmonic, N being the normal engine speed, are attenuated by interference, at the output (18) of the interference device. 2.- Dispositif d'échappement suivant la revendication 1, caractérisé par le fait que le disposi tif à interférences comporte une branche (14, 24) constituée par un simple tuyau et une branche (15, 25a, 25b, 25c) sur laquelle est interposé un silencieux transversal (20, 26a, 26b, 26c).2.- exhaust device according to claim 1, characterized in that the interference device has a branch (14, 24) constituted by a simple pipe and a branch (15, 25a, 25b, 25c) on which is interposed a transverse silencer (20, 26a, 26b, 26c). 3.- Dispositif d'échappement suivant la revendication 2, caractérisé par le fait que le silencieux (26a) est constitué par une capacité dans laquelle débouchent l'extrémité d'un tuyau d'arrivée (27) et l'extrémité d'un tuyau de sortie (28).3.- exhaust device according to claim 2, characterized in that the silencer (26a) is constituted by a capacity into which open the end of an inlet pipe (27) and the end of a outlet pipe (28). 4.- Dispositif d'échappement suivant la revendication 2, caractérisé par le fait que le silencieux (26b) est constitué par une capacité tranversée par un tuyau (29) comportant des perforations (30) dans sa partie située à l'intérieur de la capacité (26b).4.- Exhaust device according to claim 2, characterized in that the silencer (26b) is constituted by a capacity tranversé by a pipe (29) having perforations (30) in its part located inside the capacity (26b). 5.- Dispositif d'échappement suivant la revendication 2, caractérisé par le fait que le silencieux (26c) est constitué par une capacité partagée en deux chambres (26e) et (26f) au moyen d'une paroi (26d) dans lesquelles débouchent les extrémités respectivement d'un tuyau d'entrée (31) et d'un tuyau de sortie (32) et qui sont reliées par un tuyau intermédiaire (33).5.- exhaust device according to claim 2, characterized in that the silencer (26c) is constituted by a capacity shared in two chambers (26e) and (26f) by means of a wall (26d) into which open out the ends respectively of an inlet pipe (31) and an outlet pipe (32) and which are connected by an intermediate pipe (33).
EP19880400042 1987-02-12 1988-01-08 Exhaust system for a six-cylinder v-type engine Expired - Lifetime EP0279710B1 (en)

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FR8701781 1987-02-12
FR8701781A FR2610988B1 (en) 1987-02-12 1987-02-12 EXHAUST DEVICE OF A SIX V-CYLINDER ENGINE

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US5195607A (en) * 1989-11-21 1993-03-23 Mazda Motor Corporation Exhaust system for automotive engine
EP0540891A1 (en) * 1991-11-02 1993-05-12 Dr.Ing.h.c. F. Porsche Aktiengesellschaft Exhaust installation for a motor vehicle reciprocating engine
US5445241A (en) * 1991-03-25 1995-08-29 Mazda Motor Corporation Exhaust gas pipe assembly for an automotive engine
FR2855212A1 (en) * 2003-05-23 2004-11-26 Renault Sa I.c. engine exhaust system has two branches of different lengths but equal inductance connecting exhaust manifolds to common outlet
WO2009031015A2 (en) * 2007-09-06 2009-03-12 Toyota Jidosha Kabushiki Kaisha Exhaust device for vehicle internal combustion engine

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Cited By (7)

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Publication number Priority date Publication date Assignee Title
US5195607A (en) * 1989-11-21 1993-03-23 Mazda Motor Corporation Exhaust system for automotive engine
US5445241A (en) * 1991-03-25 1995-08-29 Mazda Motor Corporation Exhaust gas pipe assembly for an automotive engine
EP0540891A1 (en) * 1991-11-02 1993-05-12 Dr.Ing.h.c. F. Porsche Aktiengesellschaft Exhaust installation for a motor vehicle reciprocating engine
FR2855212A1 (en) * 2003-05-23 2004-11-26 Renault Sa I.c. engine exhaust system has two branches of different lengths but equal inductance connecting exhaust manifolds to common outlet
WO2009031015A2 (en) * 2007-09-06 2009-03-12 Toyota Jidosha Kabushiki Kaisha Exhaust device for vehicle internal combustion engine
WO2009031015A3 (en) * 2007-09-06 2009-06-18 Toyota Motor Co Ltd Exhaust device for vehicle internal combustion engine
US8434588B2 (en) 2007-09-06 2013-05-07 Toyota Jidosha Kabushiki Kaisha Exhaust device for vehicle internal combustion engine

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DE3860091D1 (en) 1990-05-23
FR2610988B1 (en) 1989-06-23
FR2610988A1 (en) 1988-08-19

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