EP1433948B1 - Air intake silencing device - Google Patents

Abstract

The noise attenuation device comprises a pipe section (1) forming a section of the air inlet circuit of the turbocharger. It is fitted with a first group of external circumferential chambers (5) located in parallel about the pipe and communicating with it through parallel openings (2) around the pipe section. An additional chamber (6) located in series with the first group of chambers communicates through an opening (3) with the pipe section. An Independent claim is included for an engine air inlet circuit fitted with the noise attenuation device.

Description

The present invention relates to a noise attenuation device on an air intake circuit for supercharged internal combustion engine, and an air intake circuit equipped with such an attenuation device.

The main function of an air intake circuit of an internal combustion engine, equipped with a turbocharger, is to convey to the engine fresh air from the front of the vehicle by cleaning the air. However, it is found, in addition to the noise generated by the operation of the engine, the appearance of noise resulting in particular from the operation of the turbocharger. These aerodynamic type noises are in a wide band of 500 Hertz at 3000 Hertz. This noise is a component of mouth noise called sighing noise. It spreads upstream of the turbocharger. To eliminate high frequency mouth noise, absorbent and porous materials are used which are implanted in the filter housing and on the conduit. However, the acoustic performance of these porous absorbent materials is greatly affected over time by dust and infiltration of liquids. In addition, absorption attenuation requires a relatively large contact area with the circulating air. This constraint of space can result in an increase in pressure losses.

Also known noise attenuation devices for positioning on pipes carrying air under pressure, that is to say downstream of the turbocharger. The noise attenuated by such devices essentially have a high frequency component. As a result, such devices consist of external circumferential chambers communicating with the conduit via openings, as illustrated in particular by the EP1176355 where the DE-A-19943246 . In this Second document, all the rooms have the same size and therefore do not allow attenuation of noises emitted within a broad band of frequencies.

An object of the present invention is therefore to provide a noise attenuation device of the aforementioned type whose design makes it possible to dampen mouth noises extending within a large frequency range of 500 Hertz to 3 Hz. 000 Hertz.

For this purpose, the subject of the invention is a device for attenuating noise on an air intake circuit for a supercharged internal combustion engine, these noises notably stemming from the operation of the turbocompressor, this device being in the form of a duct section integrable with the circuit, this duct being equipped with a first group of external circumferential chambers, arranged in parallel around the duct and communicating with the latter through openings arranged in parallel around the duct section; to establish a communication of the air flow between the duct and the chambers allowing attenuation of the high frequency noise, the duct, able to form a section of the duct of the air intake circuit of the turbocharger, comprises at least one additional chamber arranged in series with the first group of rooms, this first group of rooms, intended for the attenuation of high frequency noise, It consists of chambers extending along the duct along a substantially axial component with respect to the longitudinal axis of the duct, while the additional chamber or chambers, which communicate by at least one opening with the duct and which are dimensioned relative to the duct. to each chamber of the first group so as to allow attenuation of the medium frequency noise of the circuit, extend substantially transversely to the duct so as to limit the bulk of the assembly, the duct (1) further comprises openings (4 ) opening into the air to attenuate low frequency noise.

This arrangement of the rooms both in series and in parallel on the circuit being accompanied on the one hand by a different orientation of the rooms, on the other hand In particular rooms dimensioning, namely large chamber volumes for medium frequency attenuation and lower volumes for high frequency attenuation, allows attenuation of noises over a wide frequency range for reduced space requirements. together.

According to a preferred embodiment of the invention, the chambers of the first group, which extend along the conduit in a substantially axial component relative to the longitudinal axis of the conduit, communicating with the conduit via oblong and axial openings to said duct .La or the attenuation chambers of the medium frequency noise, which extend substantially transversely to the duct, are in the form of annular or semi-annular chambers. These medium frequency noise attenuation chambers communicate with the conduit via openings, preferably oblong, and transverse to said conduit. Thus, the rooms for the attenuation of high frequency noise are low volume chambers whose axial arrangement and in parallel to limit the size on the conduit. It is the same rooms for attenuation of mid-frequency noise which, despite their large volume, do little clutter the duct due to their provision essentially transverse duct. Moreover, this combination of axial chambers and transverse ducts makes it possible to have an extremely high dimensional dimension between chambers, thus increasing the acoustic possibilities.

The invention also relates to an air intake circuit for supercharged internal combustion engine, said circuit comprising at least one air inlet, an air filter and a turbocharger connected together by a conduit, characterized in that the inlet duct section of the turbocharger, extending upstream of the air filter or respectively downstream of the air filter, is equipped with a noise attenuation device of the aforementioned type.

• la figure 1 représente une vue schématique d'ensemble d'un circuit d'admission d'air pour moteur à combustion interne suralimenté et
• la figure 2 représente une vue en perspective d'un dispositif d'atténuation des bruits conforme à l'invention en position éclatée des demi-coquilles.

The invention will be better understood on reading the following description exemplary embodiments, with reference to the accompanying drawings in which:

• the figure 1 represents a schematic overview of an air intake circuit for a supercharged internal combustion engine and
• the figure 2 represents a perspective view of a noise attenuation device according to the invention in the exploded position of the half-shells.

The noise attenuation device, which is the subject of the invention, is more particularly intended to be positioned on an air intake circuit for a supercharged internal combustion engine. An example of such an air intake circuit is shown in FIG. figure 1 . Generally, such circuits comprise at least one air inlet, an air filter 12 and a turbocharger 11 interconnected by a conduit. The turbocharger 11 is itself connected at the output to a motor 10 via a circuit equipped in its path with an exchanger 13.

The device, which is the subject of the invention, is intended in particular to attenuate the noises resulting from the operation of the turbocharger 11. It turns out that these noises generated by the turbocharger are not propagated in the direction of the air flow. These noises indeed have a tendency to go up towards the mouth of admission. Consequently, the noise attenuation device according to the invention is in the form of a duct capable of constituting a section of the duct of the air inlet circuit of the turbocharger 11. Such a device is therefore positioned upstream. turbocharger 11, upstream or downstream of the air filter 12. In the example shown in FIG. figure 1 , this noise attenuation device is positioned upstream of the air filter 12. As illustrated in the figures, this noise attenuation device is in the form of a section 1 of duct that can be integrated into the input circuit of the turbocharger 11. This duct section 1 has openings 2, 3 communicating with chambers 5, 6 arranged around the duct section to establish a communication of the air flow between duct 1 and chambers 5, 6. the invention, this duct 1, able to form a section of the duct of the air intake circuit of the turbocharger 11, comprises at least two openings 2, 3 arranged in series along the duct and each communicating with a chamber 5, 6 of differentiated orientation. At least one of the openings in the series consists of a plurality of so-called axial openings positioned in parallel circumferentially to said circuit. Each opening 2 in parallel communicates with a so-called axial chamber 5 so as to attenuate noise emitted at high frequency. The chambers 5 are said to be axial because their longitudinal component extends substantially parallel to the longitudinal axis of the duct 1. These chambers 5 can be arranged in parallel around the duct 1 because of their small volume. These axial chambers are arranged in series with at least one chamber 6 transverse to said duct 1. In the example shown in FIG. figure 2 , the duct 1 comprises two transverse chambers arranged axially offset along the duct 1 and in series with the group of chambers 5. This gives a group of openings 2 and 5 followed by chambers, along the duct 1, a first opening 3 communicating with a first transverse chamber 6 and a second opening 3 communicating with a second chamber 6. These transverse openings 3 open into a chamber 6 preferably annular or semi-annular extending at least partially around said duct 1 so as to attenuate noise emitted at medium frequency. This positioning of the openings and the chambers both in series and in parallel on said circuit makes it possible to obtain a dimensional ratio between the chambers which can vary within a wide range. Indeed, the axial openings 2 extending in parallel on the circumference of the duct are intended to cooperate with low volume chambers 5 arranged side by side and circumferentially around the duct. This set of chambers 5 / openings 2 allows the attenuation of noise emitted at high frequency, that is to say within a range extending beyond 1500 Hertz. Due to this parallel arrangement of the chambers and an axial development imposed by this arrangement in parallel, the chambers 5 can have a very small volume and the space requirement on the conduit is reduced. These opening / chamber assemblies also cooperate with constituted assemblies openings 3 transverse to the duct, these transverse openings 3 cooperating with chambers 6, said transverse to the duct and preferably annular or semi-annular. Due to their layout, these rooms can have a large volume. Indeed, this large volume is necessary to attenuate noise emitted at medium frequency, that is to say within a frequency range between 500 Hertz and 1500 Hertz. The fact of combining openings and axial chambers with openings and chambers transverse to the longitudinal axis of the duct makes it possible, for a small bulk of the assembly, to obtain an extremely high dimensional ratio between chambers. Thus, the transverse chambers 6 cooperating with the transverse openings 3 can reach large volumes greater than the volume of each axial chamber arranged in parallel and cooperating with an axial opening. Preferably, the volume of each chamber 6 is five to twelve times that of a chamber 5. The section of the opening 2 or 3 is in turn greater than one tenth of the section of the duct 1. Thus, the volume the chamber 6 for a duct diameter of between 40 and 60 mm extends between 0.03 and 0.1 l. The combination of these rooms makes it possible to cover a wide range of frequencies.

où c correspond à la célérité du son dans l'air, S à la section de l'ouverture 3, h à la hauteur de l'ouverture 3 et V au volume de la chambre 6.In addition, the shapes and dimensions of the openings as well as the shapes and dimensions of the chambers are adapted to obtain different attenuation effects. Thus, at least one of the so-called transverse openings of the series is equipped with a neck 7 opening into a chamber, preferably annular or semi-annular, to constitute with said chamber 6 a Helmholtz type resonator whose frequency is established from the formula: $$\mathrm{f}\mathrm{=}\mathrm{vs}\mathrm{/}\mathrm{2}\mathrm{\Pi }{\left(\mathrm{S}\mathrm{/}\mathrm{h}\mathrm{\times }\mathrm{<figure-callout\; id="1"\; label="V"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">V</figure-callout>}\right)}^{\mathrm{1}\mathrm{/}\mathrm{2}}$$

where c corresponds to the speed of sound in the air, S to the section of the opening 3, h to the height of the opening 3 and V to the volume of the chamber 6.

où h correspond à la hauteur de la chambre 5 et c à la célérité du son dans l'air.Conversely, the axial openings 2 cooperate with the axial chambers 5 to obtain noise attenuation on the basis of the quarter-wave principle or to constitute expansion chambers. Generally, the section of the opening 2 corresponds substantially to the section of the chamber 5. The frequency of this quarter-wave resonator is established from the formula: $$\mathrm{f}\mathrm{=}\mathrm{vs}\mathrm{/}\mathrm{4}\mathrm{\times }\mathrm{h}$$

where h is the height of chamber 5 and c is the speed of sound in the air.

To further increase the frequency range covered, the conduit 1 further comprises openings 4 opening into the air to attenuate the low frequency noise, that is to say those produced at a frequency less than 500 Hertz. These openings 4 of the duct 1 opening into the open air are positioned on either side of a series of openings 2, 3 opening into chambers 5, 6. These openings here consist of simple axial slots, c that is to say longitudinal axis parallel to the longitudinal axis of the conduit 1. These openings 4 have a width of about 1% of the perimeter of the conduit, for example 11.5 to 2.5 mm and a length of the order of the duct diameter is 40 to 60 mm.

In the examples shown, the openings 2, 3, 4 of the duct are manufactured with the duct, the chambers 5, 6 being formed from parts 8A, 8B reported around said duct. The chambers 5, 6 of the device are thus formed from two half-shells 8A, 8B attached around said duct 1. These half-shells 8A, 8B have a curved inner profile 9 adapted to be adapted in the manner of a saddle to the profile of the duct 1. Thus, the lateral or transverse faces of said shells have this curved profile while the longitudinal faces are in contiguous contact once positioned on either side of the duct by enclosing the latter.

In the examples shown, these half-shells 8A, 8B are held on said conduit by connection, in particular by snapping the half-shells together. The chambers 5, 6 are obtained by partitioning the half-shells by means of walls extending substantially parallel or orthogonal to the longitudinal axis of the duct 1. Thus, the chambers 5 arranged in parallel are obtained from of partitions extending between the transverse walls of the half-shells, perpendicular thereto, while the chambers 6 intended to cooperate with the transverse openings 3 of said duct are obtained from partitions extending parallel to the transverse walls of the half-shells. These half-shells can still be connected together by welding and / or bonding. These half-shells may also be held assembled to the conduit by bonding such as welding or gluing between half-shells and conduit. In the examples shown, because the half-shells are interconnected by snapping, the connection between the half-shells and the conduit is a non-sealed connection. However, because of the positioning of the device upstream of the turbocharger, this duct portion being in depression, sealing is not essential.

Such an attenuation device is in fact arranged to be positioned on the input circuit of the turbocharger, either upstream of the air filter 12 equipping the input circuit of the turbocharger 11, or downstream of the air filter 12 between filter The noise attenuated by means of such a device may extend within an extremely large frequency range between 500 Hertz and 3000 Hertz.

Claims (13)

1. Air intake silencing device for a turbocharged internal combustion engine (10), the noise to be silenced arising particularly from operation of the turbocharger (11), this device taking the form of a section (1) of duct incorporable in the intake system, this duct (1) being provided with a first group of external circumferential chambers (5), arranged in parallel around the duct (1) and communicating with the latter via openings (2) arranged in parallel around the section of duct (1) to establish a communication of the air flow between the duct (1) and chambers (5), making possible an attenuation of high frequency noise, this duct (1), suitable for forming a section of the duct of the turbocharger (11) air intake system, comprising at least one supplementary chamber (6) arranged in series with the first group of chambers (5), this first group of chambers (5), intended for the attenuation of high frequency noise, being formed from chambers running along the duct according to a component which is essentially axial with respect to the longitudinal centre-line of the duct, whereas the supplementary chamber or chambers (6), which communicate via at least one opening (3) with the duct (1) and which are dimensioned with respect to each chamber of the first group so as to make possible an attenuation of the intake system's medium frequency noise, run essentially transversely to the duct so as to limit the assembly's bulk, characterized in that the duct (1) also comprises openings (4) to the open air so as to attenuate low frequency noise.
2. Silencing device according to Claim 1, characterized in that the medium frequency noise attenuation chamber or chambers (6) take the form of preferably annular or semi-annular chambers, running essentially transversely with respect to the duct (1), the said chambers (6) communicating with the duct (1) via openings (3) which are preferably oblong and transverse with respect to the said duct (1).
3. Silencing device according to Claim 2, characterized in that at least one of the so-called transverse openings (3) of the series of openings (2 and 3) communicating with a medium frequency noise attenuation chamber (6) is provided with a neck (7) leading to the said chamber (6) to form, with the said chamber (6), a Helmholtz type resonator.
4. Silencing device according to one of Claims 1 to 3, characterized in that the first group chambers (5), which run along the duct (1) following a component which is essentially axial with respect to the longitudinal centre-line of the duct, communicate with the duct (1) via openings (2) which are oblong and axial with respect to the said duct (1).
5. Silencing device according to Claim 1, characterized in that the duct (1) openings (4) leading to the open air are positioned on either side of a series of openings (2 and 3) leading to chambers (5 and 6).
6. Silencing device according to one of Claims 1 to 5, characterized in that the openings (2, 3 and 4) in the duct are as made with the duct section (1), the chambers (5 and 6) being formed from parts (8A and 8B) attached around the said duct (1).
7. Silencing device according to one of Claims 1 to 6, characterized in that the device chambers (5 and 6) are made from two half-shells (8A and 8B) attached around the said duct (1), the half-shells (8A and 8B) having a curved inner profile (9) suitable for fitting the profile of the duct (1) as a saddle would.
8. Silencing device according to Claim 7, characterized in that the chambers (5 and 6) are obtained by partitioning the half-shells by means of walls running substantially parallel with or at right angles to the longitudinal centre-line of the duct (1).
9. Silencing device according to Claim 7 or 8, characterized in that the half-shells (8A and 8B) are held on the said duct by connection, in particular by catching of the half-shells with each other.
10. Silencing device according to Claim 7 or 8, characterized in that the half-shells (8A and 8B) are joined together by welding and/or adhesive bonding.
11. Silencing device according to Claim 7 or 8, characterized in that the half-shells are kept assembled with the duct by joining means such as welding or adhesive bonding between the half-shells and duct.
12. Silencing device according to one of Claims 1 to 11, characterized in that it is prepared for being positioned either ahead of the air filter (12) provided in the turbocharger (11) intake system or beyond the air filter (12) system provided in the turbocharger (11) intake system.
13. Air intake system for a turbocharged internal combustion engine (10), the said system comprising at least one air intake, one air filter (12) and one turbocharger (11), joined together by a duct, characterized in that the turbocharger (11) intake duct section (1), running ahead of the air filter (12) or beyond the air filter (12) respectively, is provided with a silencing device according to one of Claims 1 to 12.

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