GB2584399A

GB2584399A - Air intake component and system

Info

Publication number: GB2584399A
Application number: GB1906407.0A
Authority: GB
Inventors: Owen Griffiths Connor
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2019-05-07
Filing date: 2019-05-07
Publication date: 2020-12-09
Anticipated expiration: 2039-05-07
Also published as: GB201906407D0; GB2584399B

Abstract

The present invention provides a component for an air intake system of an engine, the component comprising: an expansion chamber 117 comprising an inlet and an outlet; an acoustic resonator 101 adjacent the expansion chamber and constructed such that at least a portion of a wall of the acoustic resonator forms a shared wall 106 with the expansion chamber; and a duct 113 or 111, said duct being in fluid communication with the inlet or the outlet of the expansion chamber via a first opening and in fluid communication with the acoustic resonator via a second opening (holes 105). The shared wall is provided with one or more perforations 103. A second acoustic resonator may also be fitted (see figure 3). The sound attenuation provided by a system of a given packaging volume may be improved by embodiments of the present invention. An air intake system and a vehicle are also claimed.

Description

Air Intake Component and System

TECHNICAL FIELD

The present disclosure relates generally to air intake systems for engines, particularly, but not exclusively, to air intake systems for engines of automotive vehicles. Aspects of the invention relate to a component for an air intake system of an engine, to an air intake system, and to a vehicle.

BACKGROUND

It is known to provide vehicle with an engine air inlet having an air cleaner box disposed in the air flow path. Such an air cleaner box typically contains a filter element that removes particulate matter from the incoming air. The presence of an air cleaner box also has the effect of attenuating noise from the engine and/or a compressor of a turbocharger or supercharger that may be downstream of the air cleaner box, as the air cleaner box provides a sudden change to the cross sectional area of the air flow path. The sudden cross-sectional change causes an expansion of the propagating sound waves to take place within the air cleaner box, this has the effect of attenuating some of the sound that enters the air cleaner box.

It is known to provide an acoustic resonator in the air inlet path in addition to the air cleaner box. This provides additional attenuation of the sound generated by the engine and/or the compressor, but has the disadvantage of requiring additional packaging space, which is often limited in modern vehicles.

It is an aim of the present invention to address one or more of the disadvantages

associated with the prior art.

BRIEF SUMMARY OF THE INVENTION

Aspects of the invention provide a component, an air intake system and a vehicle as defined in the appended claims.

According to an aspect of the present invention for which protection is sought, there is provided a component for an air intake system of an engine, the component comprising: an expansion chamber comprising an inlet and an outlet; an acoustic resonator adjacent the expansion chamber and constructed such that at least a portion of a wall of the acoustic resonator forms a shared wall with the expansion chamber; and a duct, said duct being in fluid communication with the inlet or the outlet of the expansion chamber via a first opening and in fluid communication with the acoustic resonator via a second opening, wherein the shared wall of the expansion chamber and the acoustic resonator is permeable to enable fluid communication between the expansion chamber and the acoustic resonator. Advantageously, such a component may provide improved acoustic performance in a given package volume. In some embodiments, the number and/or size of the perforations may be adjusted to optimise the acoustic performance for a particular situation.

In an embodiment the shared wall of the expansion chamber and the acoustic resonator is permeable due to one or more perforations being provided in the shared wall.

In an embodiment, the duct is an inlet duct for allowing fluid to flow into the expansion chamber, and the first opening is in fluid communication with the inlet of the expansion chamber.

In another embodiment, the duct is an outlet duct for allowing fluid to flow out of the expansion chamber and the first opening is in fluid communication with the outlet of the expansion chamber. The source of the noise to be attenuated by the component is typically an engine and/or a compressor of a supercharger or turbocharger that supplies the engine. Accordingly, the outlet duct is closer to the source of the noise than the inlet duct, so improved acoustic performance may be obtained by placing the acoustic resonator in fluid communication with the outlet duct of the expansion chamber.

Optionally, the acoustic resonator is a Helmholtz resonator. Alternatively, the acoustic resonator is a quarter wave tube resonator, a broadband resonator or a further expansion chamber.

In an embodiment, an air filter element is provided in the expansion chamber between the inlet and the outlet. In this way, the expansion chamber may function as an air cleaner box. Indeed, the component may comprise an air cleaner box with one or more internal resonators.

In an embodiment, the surface area of the shared wall is between 1 and 25% perforated, preferably between 1 and 10% perforated. Optionally, the one or more perforations are between 1 and 25 millimetres in diameter, preferably between 5 and 10 millimetres in diameter. It has been determined that these ranges of perforation size provide optimal acoustic performance.

Optionally, the shared wall of the expansion chamber is at least partially formed of a permeable material. The perforations may be partially or fully covered by the permeable material; what is important is that the perforations in the shared wall provide for some fluid communication between the expansion chamber and the internal volume of the resonator.

In an embodiment, the component further comprises a second acoustic resonator adjacent to the expansion chamber constructed such that at least a portion of a wall of the second acoustic resonator forms a second shared wall with the expansion chamber wherein the second shared wall is permeable to enable fluid communication between the second acoustic resonator and the expansion chamber. Advantageously, provision of two internal acoustic resonators may further improve the acoustic performance that can be obtained within a given package volume.

In an embodiment a second duct is provided, the second duct being in fluid communication with the inlet of the expansion chamber via a third opening and in fluid communication with the second acoustic resonator via a fourth opening.

In an embodiment the second opening and/or the fourth opening comprises a slot that extends along the entire circumference of the duct, whereby the duct is discontinuous. Such a discontinuous duct may improve the attenuation provided by the internal resonator by increasing the surface area of the connection between the duct and the resonator.

However, it will be understood that such a discontinuous duct still guides the bulk flow of air through the duct and into or out of the expansion chamber.

According to another aspect of the invention for which protection is sought there is provided an air intake system comprising a component as described above.

Optionally, the outlet is fluidly connected to a compressor inlet of an engine intake. The compressor may be a component of a turbocharger or a supercharger arranged to provide compressed air to the engine.

According to another aspect of the invention for which protection is sought, there is provided a vehicle comprising a component or an intake system as described above.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described by way of example only, with reference to the accompanying figures, in which: Figure 1A shows an air induction component with a separate air cleaner and resonator (Prior Art); Figure 1B shows a reduced envelope air induction component with no resonator (Prior Art); Figure 2A shows a cross sectional view of an embodiment of the present invention; Figure 2B shows an alternative cross sectional view of an embodiment of the present invention; Figure 3 shows a cross sectional view of a further embodiment of the present invention; Figure 4A shows a graph of data obtained from a computer-aided engineering model of the transmission loss at various frequencies, for an air cleaner with no resonator and an air cleaner with an internal resonator; Figure 4B shows a graph of data obtained from a computer-aided engineering model of the transmission loss at various frequencies, for an air cleaner with an internal resonator, an air cleaner with an internal resonator with a shared wall having a single perforation, and an air cleaner with an internal resonator with a double perforated shared wall; Figure 4C shows a graph of data obtained from a computer-aided engineering model of the transmission loss at various frequencies, for an air cleaner with no internal resonator, an air cleaner with an internal resonator and an air cleaner with two internal resonators; Figure 4D shows a graph of data obtained from a computer-aided engineering model of the transmission loss at various frequencies, for an air cleaner with no internal resonator, an air cleaner with a broadband resonator, wherein one of the shared walls includes six perforations; Figure 4E shows a graph of experimental transmission loss data at various frequencies obtained from physical models of components according to embodiments of the present invention; Figure 4F shows a graph of transmission loss data between 0 and 500Hz obtained from the same model as figure 4E; and Figure 5 shows an aspect of the present invention, a vehicle comprising an air induction system with an air clean box according to any previously described embodiment.

DETAILED DESCRIPTION

Figure 1A shows a prior art air intake system 1 with an inlet duct 11, an outlet duct 13, an expansion chamber 17 which contains an air filter element 19, which splits the expansion chamber into a clean side 20 and a dirty side 18. The inlet duct 11 allows air to flow into the dirty side of the expansion chamber 17 and through the air filter element, which removes particulate matter which would otherwise adversely affect the engine. This may include mud, insects, gravel and dust. Clean air is then allowed to flow from the clean side 20 through the outlet duct 13 to the downstream component 22, which may be a compressor of a supercharger or turbocharger arranged to provide compressed air to an engine (not shown). Alternatively, the downstream component 22 may be a naturally aspirated engine. An acoustic resonator such as a Helmholtz, broadband or quarter wave tube resonator 15 is provided in the outlet duct 13. The main function of the resonator 15 is to attenuate airborne noise, which can reduce the amount of uncomfortable noise reaching the cabin of the vehicle or pedestrians located outside the vehicle. Acoustic noise reduction from engine and/or compressor to the intake orifice is typically described in terms of a transmission loss, measured in decibels (dB).

In addition to the resonator 15, another significant source of transmission loss is the expansion volume that is present in the air cleaner box 20, which can be considered as a simple low to mid frequency attenuator. The characteristics of this attenuator are determined by the ratio of the cross-sectional area of the clean-side duct to the cross-sectional area of the chamber, the length of the chamber and the volume of the chamber. For a 4-stroke engine, an approximate rule sometimes used by acoustic engineers to ensure adequate noise attenuation by the air cleaner box is to provide an expansion chamber volume of the order of 20 times the swept volume of a single cylinder. However, there are constraints on the amount of volume each component in a vehicle can take up, especially in modern hybrid vehicles that require an increased number of components under the bonnet compared to conventional vehicles powered solely by a combustion engine. In general, it is desirable to reduce the space and weight required by each component.

Figure 1B shows another prior art air intake system with a reduced overall volume compared to the system shown in figure 1A. In this example the air induction component has an inlet duct 11, an outlet duct 13, an expansion chamber 17 which contains an air filter element 19 which splits the expansion chamber into a clean side 20 and a dirty side 18. However, the resonator 15 shown in figure 1 A is not provided. Deletion of the resonator 15 reduces the volume of the air induction system, but has a drawback in that less noise from the engine/ air induction system will be attenuated, potentially leading to increased discomfort for those in or near the vehicle.

As will be apparent from the above discussion of figures 1A and 1B, designers of air intake systems presently face a trade-off between the level of transmission loss provided by the air intake system and the package volume of the air intake system. In general, increasing the level of transmission loss will also lead to an undesirable increase in the package volume.

Figure 2A shows a cross sectional view of one embodiment of the present invention. The integrated resonator air induction component 100 comprises an inlet duct 111, an outlet duct 113, an expansion chamber 117 containing an air filter element 119 which splits the expansion chamber into a clean side 20 and a dirty side 118. The component 100 further comprises an internal resonator 101 which shares wall 106 with the expansion chamber 117, the outlet duct further comprises a plurality of holes 105 that allow fluid communication between the outlet duct and the resonator. The shared wall between the internal resonator and the expansion chamber is provided with perforations 103 such that the shared wall is permeable and the expansion chamber is in fluid communication with the internal resonator. The perforations 103 in the wall allow the expansion chamber 117 to behave as if it at least partially included the volume of the internal resonator 101, thereby offsetting the potential negative impact of the inclusion of the resonator 101 within the expansion chamber on the attenuating behaviour of the expansion chamber due to reduced volume. The perforations can also be optimised, in terms of size and number, to attenuate noise in the 0-500Hz frequency range which contains the majority of noise produced by typical engines. The internal resonator 101 is also in fluid communication with the outlet duct 113 which allows it to attenuate noise coming from the engine. Accordingly, the overall level of sound attenuation that can be provided within a given packaging volume may be improved.

The behaviour of the internal resonator 101 and the expansion chamber can be tuned by changing the size and number of perforations 103 in the shared wall 106 as well as the plurality of holes 105 in the outlet duct 113. In particular, the transmission loss at different frequencies may be tuned to match a required frequency range by varying the number and size of the perforations. For practical systems, computational and/or experimental methods may be used to determine the optimal size and number of perforations.

Figure 2B shows another cross sectional view of the embodiment of the invention shown in figure 2A. It will be understood that the perspective shown in figure 2B has the inlet duct 111 and the outlet duct 113 going into and coming out of the page, respectively. The inlet duct 111 allows uncleaned air into the lower, dirty half of the expansion chamber this air then flows through the air filter 119 and into the clean half of the expansion chamber. In the illustrated embodiment the air filter 119 is a folded paper filter element, although it will be understood that other filter elements could also be used. Because of the perforations 103 in the wall 106, the volume between the duct 113 and the outer walls of the resonator 101 is able to at least partially contribute to the sound attenuation by both the expansion chamber 117 and the resonator 101. As will be discussed in more detail below, this can provide improved sound attenuation for a given packaging volume whilst partially maintaining the low-to-mid frequency benefit of the air cleaner expansion. Furthermore, tuning of the attenuation performance can be provided by adjusting the size and number of perforations 103 that are provided.

In the illustrated embodiment, there are four perforations 103 visible on the portion of shared wall 106 that is normal to the direction of flow through the outlet duct 113. However, it will be understood that this is merely an example, and that various other configurations could also be provided. In other embodiments, there may be one or more perforations and when there are more than one the perforations may be of different sizes and/or shapes. The portion of the outlet duct that is within the resonator also has openings (not shown) which allow fluid communication between the outlet duct and the resonator, thus allowing for further attenuation. In some embodiments the one or more perforations may be partially or wholly covered by a permeable material, such as felt, gauze, mesh, foam, fibreglass, acoustic wool or paper. Alternatively, the shared wall may consist of a permeable material, and the fluid communication between the resonator and the expansion chamber may be provided by the permeability of the shared wall.

Figure 3 shows a shows a cross sectional view of another embodiment of the present invention. The air induction component 200 comprises an inlet duct 211, an outlet duct 213, an expansion chamber 217 which contains an air filter element 219 that splits the expansion chamber into a clean side 220 and a dirty side 218. The component is provided with a resonator 201A on the outlet duct. This resonator is essentially the same as the resonator 101 described with respect to figures 2A and 2B, so it will not be described in detail again here.

In the embodiment shown in figure 3, the inlet duct 211 is also connected to a second internal resonator 201B via one or more second openings 225 such that the resonator 201 B is in fluid contact with the inlet duct 211 via these openings 225. The shared wall between the internal resonator 201 B and the dirty side 218 of the expansion chamber 217 is provided with perforations 223 such that the expansion chamber 217 is in fluid communication with the internal resonator 201. Again, the perforations 223 in the wall allow the expansion chamber 217 to behave as if it at least partially included the volume of the internal resonator 201 B, thereby offsetting the potential negative impact on the attenuating behaviour of the expansion chamber arising from the inclusion of the second resonator 201 B within the volume of the expansion chamber. The internal resonator 201 B is also in fluid communication with the inlet duct 211 which allows it to attenuate noise resulting from air intake and the engine.

A particular advantage of the present invention is that it may be possible to tune the attenuation behaviour of the component by varying the size and number of holes within the shared wall. This may allow the component to be adapted for the specific engine fitted within a particular vehicle, without affecting the packaging requirements of the intake system. However, it will be noted that the size and number of holes in the shared wall may also be adjusted for other reasons, for example to better facilitate air flow to or from the air filter element or to improve manufacturability.

It will be understood that for a practical air intake system incorporating a component according to an embodiment of the present invention, the expansion chamber will be designed to suit a wide variety of requirements in addition to optimising noise attenuation and packaging space. For example, it is typically essential that the filter of an air intake system is accessible so as to be serviceable and/or removable by a user, and it is also generally desirable that the pressure loss within the air intake system should be as low as possible. In this regard, it is important to differentiate between the pressure loss introduced by a component when a steady flow of air is passed through the component, and the loss of sound pressure caused by resonation of the sound waves within the component. It is generally desirable that the pressure loss experienced for a steady flow be as low as possible, whereas it may be desirable to increase the attenuation of sound waves that pass through the component.

Figure 4A shows a graph of data obtained from a computer-aided engineering model which compares Transmission Loss for a range of acoustic frequencies between 0 Hz and 1500 Hz for a prior art air cleaner box 50 with no internal resonator with an air cleaner box 300 which is provided with an integrated resonator. Line 50L shows the performance of the component 50, and line 300L shows the performance of the component 300.

The integrated resonator air induction component 300 comprises an inlet duct 311, an outlet duct 313 and an expansion chamber 317. The filter element is not provided in the model. The component further comprises an internal resonator 301 which shares a wall with the expansion chamber 317. The outlet duct further comprises two slits 319 being spaced apart from each other by 180 degrees in the circumferential direction) that allow fluid communication between the resonator and the outlet duct. The shared wall between the internal resonator and the expansion chamber is not perforated. For all frequencies between approximately 400Hz and approximately 1100Hz, the transmission losses are higher for the integrated resonator air induction component 300 than the component 50, meaning that less noise will be transmitted from the engine to the passengers and/or nearby people. At lower frequencies (around 250 to 350Hz) there is a small trough 551 in transmission loss for the integrated resonator compared to no resonator. However, there is a peak 552 in the transmission loss for the integrated resonator around 525 Hz as well as a general increase in transmission losses for all frequencies above approximately 425 Hz compared to the no internal resonator component.

Figure 4B shows a graph of data obtained from a computer-aided engineering model which compares Transmission Loss for a range of acoustic Frequencies between 0 Hz and 1500 Hz for the air cleaner box 300 described above compared with embodiments of the present invention. An embodiment comprises an integrated resonator air induction component 400, the integrated resonator air induction having an inlet duct (not shown, but similar to the inlet duct 311 on component 300), an outlet duct 413 and an expansion chamber 417. The component further comprises an internal resonator 401 which shares a wall with the expansion chamber 417, the outlet duct further comprises a slot such that the resonator is in fluid contact with the outlet duct via the slot. A single perforation is provided in the shared wall between the expansion chamber and the internal resonator in the component 400 a further embodiment comprising an integrated resonate air induction component 500 is also shown in figure 4B. The component 500 comprises the same features as the component 400, but two perforations are provided in the shared wall between the expansion chamber and the internal resonator 501.

The graph compares transmission losses for each case. Line 300L illustrates the performance of component 300, line 400L illustrates the performance of component 400, and line 500L illustrates the performance of component 500. As can be seen primary response frequency of the resonator is observed between approximately 500 and 600Hz.

The position and breadth of the peak varies according to the number of perforations in the wall of the resonator, with an increasing number of perforations tending to increase the frequency at which the peak occurs, and reduces the amplitude of the peak. Another feature of the graph is that increasing the number of perforations increases the transmission loss between approximately 250Hz and approximately 400Hz, without affecting the height of the first peak at approximately 250Hz.

Accordingly, the size and number of perforations is an optimisable parameter that can be varied to tailor the acoustic performance of a component, to increase transmission losses at specific frequencies or ranges of frequencies. This may allow a component to be specifically designed for an engine and/or compressor that produces noise at a known range of frequencies.

Figure 4C shows a graph of data obtained from a computer-aided engineering model which compares Transmission Loss for a range of acoustic Frequencies between 0 Hz and 1500 Hz for an air cleaner box with no internal resonator 50, an air cleaner box 600 which has two internal resonators but no perforations in the shared walls between the resonators and the air cleaner box, and an integrated double resonator air induction component 700 in an embodiment of the present invention. The integrated resonator air induction component comprises an inlet duct 711, an outlet duct 713, an expansion chamber 717 a perforated wall between one of the internal resonators and the expansion chamber. The air filter element is not accounted for in the model shown in figure 4C. The component further comprises a first internal resonator 701 in fluid communication with the outlet duct 713.

The first internal resonator shares a wall 720 with the expansion chamber 717, which wall is provided with six perforations 722. The outlet duct comprises two spaced apart slits 724 such that the resonator is in fluid contact with the outlet duct via these slits. The component 700 also comprises a second internal resonator 730 on the inlet duct 711. The inlet duct 711 is provided with two slits 732 such that the resonator 730 is in fluid contact with the inlet duct 711 via these slits 732.

The component 600 is also provided with two internal resonators 601, 630. These resonators are substantially the same as the integrated double resonator described above, except that neither of the resonators 601, 630 is provided with perforations in the shared wall between the expansion chamber and the integrated resonator.

The graph illustrates the acoustic performance of each of the components 50, 600, 700. Line 50L shows the performance of component 50, line 600 shows the performance of resonator 600L, and line 700L shows the performance of resonator 700.

As can be seen from the graph in figure 4C, the components 600, 700 provide increased transmission losses compared to the component 50 for most frequencies between 500Hz and approximately 1325Hz. Provision of the perforations in component 700 increases the transmission losses at higher frequencies (i.e. >1100 Hz).

Figure 4D shows a comparison between the acoustic performance of another prior art air cleaner box 60 and a component 900 in an embodiment of the present invention. Component 900 is an air cleaner box provided with a plurality of internal resonators. In the graph, line 60L illustrates the acoustic performance of resonator 60, line 900L illustrates the performance of resonator 900, and line 1000L illustrates a target attenuation performance, which is based on the expected noise output from a particular V8 engine. The perforations and the number of resonators provided on component 900 have been optimised to give acoustic performance that matches the target profile shown by line 1000L as closely as possible.

Air cleaner box 900 comprises a broadband resonator having three separate chambers 901A-C. Each chamber is in fluid communication with the outlet duct 913 via a respective slit in the outlet duct (not shown). The air cleaner box 900 further comprises and inlet duct 911. An air filter element would also be provided in a production embodiment. However, the influence of the air filter element on the acoustic performance is considered to be minimal, so the air filter element is not present in the illustrated model. Chamber 901C is adjacent to the expansion chamber and shares wall 903 with the expansion chamber. The wall of the middle chamber 901B of the internal resonator provided with a plurality of perforations 905B that enable fluid communication between the chambers 901 B and 901C and the expansion chamber 917. Wall 907, which separates chamber 905A from chamber 905B, is also provided with a plurality of perforations.

As shown in figure 4D, the component 60 provides a transmission loss of significantly less than the required 15dB for almost all of the 600-1200Hz range illustrated by the target profile. In contrast to this, the component 900 provides acoustic performance that is close to the required 15dB for the entire range. A peak around 875Hz and a small trough around 1025Hz are present, but both of these remain acceptably close to the required 15dB. It will be clear from the images of the air cleaner boxes 60, 900, that both of these components can be fitted within exactly the same packaging space.

Figure 4E shows a comparison between the experimentally-determined acoustic performance of another prior art air cleaner box 1100 (represented by line 1100L), an example air cleaner box 1102 (represented by line 1102L) having a resonator but no perforations in the duct or wall, an example 1104 (represented by line 1104L) having a broadband resonator within the air cleaner box and a plurality of openings in the duct, but no perforations in the wall, an embodiment of the present invention 1106 (represented by line 1106L) having openings in the duct and five perforations in the wall, and a further embodiment of the present invention 1108 (represented by line 1108L), having openings in the duct and ten perforations in the wall.

As can be seen from figure 4F all of the cleaner boxes shown have similar acoustic performance at lower than 400Hz. It can be seen that the various air cleaner boxes begin to have different levels of transmission loss at frequencies above 400Hz, with significant variations observed at higher frequencies. As is evident from the difference between lines 1106L and 1108L, varying the number of perforations in the shared wall changes the transmission loss profile. For example, introducing perforations in the shared wall and increasing the number of perforations reduces the height of the peak between 500 and 650Hz and the peak between 850 and 950Hz. Accordingly, the embodiments 1106 and 1108 are able to relatively closely match the target profile 1000L.

It will be understood that the transmission loss may be tuned to the noise profile generated by a particular engine and that varying the number and size of the perforations in the shared wall and the duct allows for the transmission loss to be tuned to approximate substantially and desired the target profile.

As will be apparent from the above examples, the present invention improves the acoustic performance that can be obtained within a given package volume, and also provides additional tuneable parameters (i.e. the size and number of perforations; the number of internal resonators provided) that may allow a designer to tune the acoustic performance to the requirements of a particular situation in a manner that is not possible for prior art arrangements. The effects of the present invention are particularly evident at higher frequencies (greater than about 500Hz in the illustrated embodiments). In some implementations this may be a particularly advantageous feature, as it may be particularly desired to attenuate the higher-frequency components of the noise generated by an engine and/or compressor.

Figure 5 shows a vehicle 1200 in which the present invention may be used.

As used herein the term "resonator" may refer to any device or component that may be used to attune or resonate sound or pressure waves, including but not limited to a Helmholtz resonator, a quarter wave tube resonator, a broadband resonator and an expansion chamber. The term "resonator" may be used interchangeably with "acoustic resonator".

As used herein the term "expansion chamber" may refer to any device or component which has a larger or substantially equal volume, dimensions or internal surface area to an upstream device or component.

As used herein the term "air cleaner box" and "expansion chamber" refer to the same object, which has two functions, firstly as an expansion chamber which aids with acoustic attenuation and secondly as an air cleaner which prevents undesirable matter entering the engine via the air intake system.

As used herein the term "attenuation" refers to changing the properties of acoustic waves, generally by increasing transmission losses at certain frequencies or ranges of frequencies.

Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example "comprising" and "comprises", means "including but not limited to", and is not intended to (and does not) exclude other moieties, additives, components, integers or steps.

Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

Claims

CLAIMS1. A component for an air intake system of an engine, the component comprising: an expansion chamber comprising an inlet and an outlet; an acoustic resonator adjacent the expansion chamber and constructed such that at least a portion of a wall of the acoustic resonator forms a shared wall with the expansion chamber; and a duct, said duct being in fluid communication with the inlet or the outlet of the expansion chamber via a first opening and in fluid communication with the acoustic resonator via a second opening, wherein the shared wall of the expansion chamber and the acoustic resonator is permeable to enable fluid communication between the expansion chamber and the acoustic resonator.
2. The component of claim 1 wherein the shared wall of the expansion chamber and the acoustic resonator is permeable due to one or more perforations being provided in the shared wall.
3. The component of claim 1 or claim 2 wherein the duct is an inlet duct for allowing fluid to flow into the expansion chamber, and the first opening is in fluid communication with the inlet of the expansion chamber.
4. The component of claim 1 or claim 2 wherein the duct is an outlet duct for allowing fluid to flow out of the expansion chamber and the first opening is in fluid communication with the outlet of the expansion chamber.
5. The component of any preceding claim wherein the acoustic resonator is a Helmholtz resonator.
6. The component of one of claims 1-4, wherein the acoustic resonator is a quarter wave tube resonator.
7. The component of any one of claims 1-4, wherein the acoustic resonator is a broadband resonator.
8. The component of any one of claims 1-4, wherein the acoustic resonator is a further expansion chamber.
9. The component of any preceding claim wherein an air filter element is provided in the expansion chamber between the inlet and the outlet.
10. The component of claim 2, or any one of claims 3-9 where dependent on claim 2 wherein the surface area of the shared wall is between 1 and 25% perforated, preferably between 1 and 10% perforated.
11. The component of claim 2 or any one of claims 3-10 where dependent on claim 2 wherein the one or more perforations are between 1 and 25 millimetres in diameter, preferably between 5 and 10 millimetres in diameter.
12. The component of any preceding claim wherein the shared wall of the expansion chamber is at least partially formed of a permeable material.
13. The component of any preceding claim, further comprising a second acoustic resonator adjacent to the expansion chamber constructed such that at least a portion of a wall of the second acoustic resonator forms a second shared wall with the expansion chamber wherein the second shared wall is permeable to enable fluid communication between the second acoustic resonator and the expansion chamber.
14. The component of claim 13 wherein the shared wall of the expansion chamber and the acoustic resonator is permeable due to one or more perforations being provided in the shared wall.
15. The component of claim 13 or 14 where dependent on claim 4, wherein a second duct is provided, the second duct being in fluid communication with the inlet of the expansion chamber via a third opening and in fluid communication with the second acoustic resonator via a fourth opening.
16. The component of any preceding claim, wherein the second opening and/or the fourth opening comprises a slot that extends along the entire circumference of the duct, whereby the duct is discontinuous.
17. An air intake system comprising the component of any preceding claim.
18. The system of claim 17, wherein the outlet is fluidly connected to a compressor inlet of an engine intake.
19. A vehicle comprising a component as claimed in any one of claims 1-16 or an air intake system as claimed in claim 17 or 18.