GB2546877A

GB2546877A - Contaminant separation device

Info

Publication number: GB2546877A
Application number: GB1621128.6A
Authority: GB
Inventors: Tipping Louise; Forty Roger; Sasnur Manjunath
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2015-12-15
Filing date: 2016-12-13
Publication date: 2017-08-02
Anticipated expiration: 2036-12-13
Also published as: GB201522065D0; GB2546877B; DE112016005731T5; WO2017102681A1; GB201621128D0

Abstract

A contaminant separation device 20 for reducing flow of contaminants to the air duct 22 of a vehicle engine air induction system 12. The planar lower surface 40, 42 induce a laminar flow 60 beneath the device of contaminated air and an opening 44 permits a clean air flow 62 to separate from the laminar flow and reach the air duct. A flow guidance plate 52 may be included towards the back of the device, extending diagonally upwards and forwards. The device prevents dust, ice, water and other contaminants from entering the air duct. Low pressure above the surface and high pressure below cause the induction of low inertia air through the inlet. With the device positioned above the flow heavier contaminant particles are restricted from entering the inlet due to gravity. A method extracting clean air from contaminated air, an air induction system for a vehicle and a vehicle using such a device are also disclosed.

Description

Contaminant Separation Device

TECHNICAL FIELD

The present disclosure relates to a contaminant separation device for reducing flow of contaminants to the air duct(s) of a vehicle engine air induction system. Aspects of the invention relate to a contaminant separation device, to an air induction system and to a vehicle.

BACKGROUND

Conventional vehicles generally include an internal combustion engine which relies upon an ample source of air for proper combustion of supplied fuel. In order to provide the necessary airflow, such vehicles therefore typically include an air induction system.

Generally, the role of the air induction system is to provide ambient air from outside the vehicle to the engine. Air is drawn in through an exterior intake port and supplied to the vehicle engine via one or more air ducts. In order to filter out dirt and other foreign particles from the air and prevent them from entering the engine and possibly damaging the engine, the air duct(s) typically include an air cleaner comprising a filter.

In many circumstances, the air cleaner is sufficient to remove contaminants from the drawn-in air. However, in certain circumstances, the air drawn in through the exterior intake port may include contaminants such as water, snow, sand, dust or other similar particles which lower the function of the air cleaner. These contaminants can inhibit airflow through the induction system, which affects the performance of the engine. Accordingly, it is desirable to reduce the flow of contaminants to the air duct(s) of the air induction system in order to preserve the functionality and performance of the air cleaner and the induction system as a whole.

Some vehicles have bodywork configured to shroud the exterior intake port in order to reduce the flow of contaminants to the air duct(s). However, depending on the positioning of the exterior intake port and the design constraints defined by other aspects of the vehicle, such an arrangement may not be possible and/or desirable. For example, this may be the case in particular when the exterior intake port is located on the front of the vehicle.

Some vehicles have features positioned in their inlet air flow path for inducing a turbulent flow in the air causing a drop in the inertia of the contaminant particles which fall under gravity away from the inlet of the induction system. This strategy is achieved by arranging surfaces, through which the air must flow, on spaced apart planes to create turbulence. A disadvantage of this is the increase in resistance to air flow and therefore back pressure in the system reduces the efficiency of the air induction system.

SUMMARY OF THE INVENTION

Aspects and embodiments of the invention provide a contaminant separation device, an air induction system and a vehicle as claimed in the appended claims.

In a first aspect of the invention there is provided a contaminant separation device for a vehicle air induction system comprising; a planar lower surface configured to induce and/or maintain lamination in contaminated air flow beneath it, and an inlet situated in the lower surface to allow air to flow from below the surface to above the surface such that heavier particles remain within the contaminated air flow.

The advantage of this arrangement is that the laminar air flow is induced or maintained by the contaminant separation device, low pressure above the surface and high pressure below the surface causes the induction of the low inertia air through the inlet. By positioning the device above the flow of air, the heavier contaminant particles are further restricted from entering the inlet by the force of gravity.

Further to the contaminant separation device above, the inlet may be an elongate slot in the lower surface which extends across the width of the device, transverse to the direction of the laminar flow, positioned to separate the lower surface into two coplanar surfaces.

Again further to the aspects above, the inlet may have a front edge and a rear edge, the front edge disposed towards the front of the vehicle and the rear edge disposed towards the back of the vehicle, the rear edge having a flow guidance means extending upwards from the lower surface in the direction of the air flow.

Still further to the above, the flow guidance means may extend diagonally upwards and forwards.

Optionally and in addition to some aspects of the above aspects, the intersection between the lower surface and the flow guidance means may be a radiused edge.

Optionally and in addition to some aspects of the above aspects, air may be directed towards the air induction system along a passage at least partially defined by the flow guidance means.

The location and shape of the inlet act to further induce and/or maintain laminar flow along the flow path of the air.

In an aspect further to any of the aspects above, the contaminant separation device may have a substantially horizontal planar lower surface.

The arrangement of the planar lower surface is, in this aspect, parallel to the flow of the contaminated air. This flow direction is caused by the forwards motion of the vehicle.

The device may be configured such that air enters the inlet at an angle to the direction of the laminar flow. In such cases, the device may be configured such that air enters the inlet substantially perpendicular to the direction of the laminar flow. This minimises the flow of contaminant particles into the clean flow-path as there is no component of the velocity of the contaminant particles in the laminar flow that is in the direction of the entrance of the inlet.

The direction of the air flow in this aspect will further limit the ability of the contaminant particles to pass through the inlet, this is again due to their inertia and their inability to change direction. In contrast, the air has a comparatively low inertia and can therefore more easily change direction without causing turbulence.

The contaminant separation device may comprise an aerodynamic feature for directing air underneath the device. In such cases, the aerodynamic feature may be in the form of a nose region. In use, this encourages air from the ambient environment to attach to the guidance means and enter the laminar flow of the device.

According to an aspect of the invention there is provided a system for a vehicle comprising the contaminant separation device according to any of the above aspects.

According to an aspect of the invention there is provided a method for extracting clean air from a contaminated air flow in a vehicle air induction system comprising; inducing laminar flow of the contaminated air beneath a planar surface, and extracting clean air from the laminar flow from beneath the surface to above the surface through an inlet in the surface.

According to one aspect of the invention, there is provided a contaminant separation device for reducing flow of contaminants to the air duct(s) of a vehicle engine air induction system, the device adapted for fitting behind a grille disposed along the front end of the vehicle and in front of the air duct(s). The device comprises: guidance means for inducing, beneath the device, a laminar flow of contaminated air entering through the grille to by-pass the air duct(s); and an inlet to permit air from the laminar flow beneath the device to reach the air duct(s) of the intake system.

According to embodiments of the invention, air from the laminar flow beneath the device is sucked through the inlet into a clean flow-path by the action of the engine. Due to the large inertial mass of contaminant particles compared to air particles, contaminants are swept past the inlet, reducing the flow of contaminants into the clean flow-path. Accordingly, air entering the clean flow-path contains fewer contaminants than the air as originally drawn-in through the exterior intake port.

This aspect of the invention provides a device that allows an ample supply of air to be provided to a vehicle engine for combustion of fuel whilst preventing contaminants that may be present in ambient air from entering the air duct(s) of an engine air induction system. Thus, contaminant separation devices in accordance with embodiments of the invention reduce the undesirable effects of contaminants on engine air induction systems, in particular aiming to prevent contaminants inhibiting airflow through the induction system, blocking the engine intake manifold or damaging the engine. The use of a contaminant separation device in accordance with embodiments of the invention allows a vehicle to travel increased distances in conditions in which the ambient air contains high levels of contaminants.

The guidance means of the contaminant separation device may at least partially define the inlet. In such cases, the guidance means may comprise two substantially coplanar plates which may be spatially separated to define the inlet. The plates may be substantially horizontal and the inlet may take the form of an elongate slot which extends across the width of the device, transverse to the direction of the laminar flow.

The configuration of the inlet reduces the flow of contaminants into the air ducts of the induction system. For example, the geometry of the inlet ensures that the air flow velocities within the laminar flow are consistent in order to reduce the flow of contaminants into the air ducts of the induction system.

The contaminant separation device may comprise a baffle plate and air may be directed towards the air duct(s) along a passage at least partially defined by the baffle plate. Thus, the device can be configured to direct air from the laminar flow to the air induction system ducts as required and desired.

According to another aspect of the invention, there is provided a vehicle engine air induction system comprising the contaminant separation device of the previous aspect.

The vehicle engine air induction system may comprise one or more air cleaners and the contaminant separation device may be located upstream of the one or more air cleaners. Thus, the contaminant separation device preserves the functionality of the air cleaner(s).

The air cleaners may comprise paper filtering elements. In other embodiments, a synthetic filtering element may be provided. Air induction systems in accordance with embodiments of the invention may comprise any suitable air cleaner.

According to a further aspect of the invention, there is provided a vehicle comprising the engine air induction system of the preceding aspect.

The vehicle comprises a radiator and contaminated air from the laminar flow beneath the contaminant separation device may be directed to the radiator having by-passed the inlet. Thus, the contaminated air may advantageously be used for engine cooling which is not adversely affected by contaminants within the cooling airflow.

The vehicle may include a grille disposed at the front end of the vehicle and in such cases, the contaminant separation device may be fitted behind the grille. This prevents very large contaminants, which could damage the air induction system, from being drawn in through the exterior intake port and thus preserves the functionality of the contaminant separation device and the induction system as a whole. This also allows for a conventional aesthetic appearance of the front end of the vehicle.

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.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a top view of a front portion of a vehicle comprising an engine air induction system including a contaminant separation device in accordance with an embodiment of the invention;

Figure 2 is a front view of a portion of the exterior of the vehicle of Figure 1;

Figure 3 is a cross-section of the vehicle of Figure 1, taken along the line A-A;

Figure 4 is a perspective view of the contaminant separation device of Figure 1 shown in isolation;

Figure 5 is a perspective view of the contaminant separation device of Figure 1, cut across the plane A-A-A shown in Figure 4;

Figure 6 is a cross-section of the contaminant separation device of Figure 1, taken across the plane A-A-A shown in Figure 4; and

Figure 7 is a cross-section of the contaminant separation device, as shown in Figure 6, shown in situ within the air induction system of the vehicle of Figure 1.

DETAILED DESCRIPTION

Referring initially to Figure 1, a top view of a front portion of a vehicle 10 comprising an engine air induction system 12 is shown. As described above by way of background, the air induction system 12 defines an air passageway from an exterior intake port 14 located at the front end of the vehicle 10, to an engine intake manifold 16 located rearward of the exterior intake port 14 from which air is supplied to the engine 18.

It should be noted at this stage that terms such as ‘rearward’ and ‘forward’, or derivatives thereof, are to be understood to refer to directions in relation to the front and rear ends, respectively, of the vehicle 10. Furthermore, it should also be noted that the accompanying figures are schematic representations to illustrate features of the invention and are not intended to be realistic representations or reflect the scale or relative proportions of the various components. The skilled person will appreciate that the representations have been simplified for the purposes of clarity and to avoid unnecessary detail obscuring the principle form of the invention. In practice, of course, many more components would be included and since these additional conventional components would be present in practical implementations of embodiments of the invention, their presence is implied.

Returning to the figure, the air induction system 12 can generally be considered to comprise a contaminant separation device 20, two air ducts 22 and two air cleaners 28.

The contaminant separation device 20 is mounted behind the exterior intake port 14 and arranged such that at least a portion of the air drawn in through the exterior intake port 14 will subsequently enter, and pass through, the contaminant separation device 20. The contaminant separation device 20 is maintained in this configuration by virtue of attachment to a front end carrier 24. A front end carrier 24 is a frame member that extends across the width of the vehicle 10 and typically supports various aspects of a front end module of the vehicle 10, including fixings for the headlights, radiator, motor fan unit and bumpers, for example. As shown in Figure 1, the front end carrier 24 in this embodiment supports an air duct carrier 26 which defines the section of the air passageway immediately downstream of the contaminant separation device 20. Thus, air that passes through the contaminant separation device 20 subsequently enters the air duct carrier 26.

The air duct carrier 26 supports a first end 22a of each of two air ducts 22. The first ends 22a respectively define the entrances of the two air ducts 22. Downstream of the entrances, each air duct 22 defines an air passageway to the intake manifold 16 via an air cleaner 28 in the form of an air filter comprising a paper filtering element. The filtering elements prevent dirt and other foreign particles from entering the intake manifold 16 and possibly damaging the engine 18.

The air cleaners 28 separate each air duct 22 into two sections: a dirty-side duct 22b upstream of the filter, between the air duct carrier 26 and the duct carrier 26; and a clean-side duct 22c downstream of the filter. The clean-side ducts 22c terminate in a common end section 22d that defines a final common section of the air passageway. Air passing through the common end section 22d enters the intake manifold 16 and is ultimately provided to the engine 18.

The skilled person will appreciate that the air induction system 12 shown in Figure 1 is one example of a possible configuration of an air induction system 12 that is compatible with an embodiment of the contaminant separation device 20. In other embodiments, alternative air induction system arrangements are envisaged. For example, the air ducts 22 need not terminate in a final common section 22d as shown in Figure 1. In other embodiments, each air duct 22 may lead to a respective intake manifold 16. Furthermore, the air induction system 12 may comprise any appropriate number of air ducts 22. In particular, the air induction system 12 may comprise a single air duct 22.

The skilled person will also appreciate that embodiments of the invention are equally applicable to turbocharged engines, in which the air induction system 12 provides air to the engine 18 via a turbocharger rather than an intake manifold 16.

Figure 2 is a front view of a portion of the vehicle 10 of Figure 1. Below the bonnet 30 of the vehicle 10, the exterior intake port 14 of the induction system 12 is shown, behind which the contaminant separation device 20 can be seen.

Referring to Figure 3, the exterior intake port is shown covered by a protective grille 32. The grille 32 prevents large debris items from entering the air induction system 12 via the exterior intake port 14. The contaminant separation device 20 occupies the space behind the uppermost region of the protective grille 32. The contaminant separation device 20 is disposed between the protective grille 32 and the front edge of the front end carrier 24. Thus, the contaminant separation device 20 is appropriately adapted to fit in this space. That is to say, the dimensions of the contaminant separation device 20 are defined by the space available between the grille 32 and the front end carrier 24.

As will be described in more detail, the contaminant separation device 20 reduces the flow of contaminants such as water, snow, sand and dust entering the air ducts 22 whilst still allowing an ample supply of air to be provided to the engine 18. Accordingly, the contaminant separation device 20 helps preserve the functionality of the air cleaners 28 and the air induction system 12 as a whole.

Figure 4 shows a perspective view of the contaminant separation device 20 in isolation. The contaminant separation device 20 comprises two portions: a foremost body portion 34 and a rearmost mounting portion 36, each comprising a unitary structure formed from injection moulded polypropylene. As mentioned previously, the terms foremost and rearmost are intended to be understood in relation to the vehicle 10. Therefore, the body portion 34 of the contaminant separation device 20 defines the front of the device 20 and, when installed, is the portion which is in closest proximity to the exterior intake port 14. The mounting portion 36 defines the rear of the device 20, and is the portion which is attached to the front end carrier 24. The two portions 34, 36 are attached together by hot plate welding. In other embodiments, the two portions 34, 36 of the contaminant separation device 20 may be attached by any appropriate means, for example mechanical fixing, adhesive or clips. Together, the body portion 34 and mounting portion 36 define an enclosed space between left and right sidewalls 38a, 38b of the device 20.

Figure 5 shows a perspective view of the contaminant separation device 20 cut across the plane A-A-A shown in Figure 4. It will be appreciated from the figures that the cross-section of the contaminant separation device 20 is broadly similar across the majority of the width of the device 20.

The enclosed space defined by the contaminant separation device 20 constitutes an air passageway 39 extending laterally across the width of the contaminant separation device 20 between the left and right sidewalls 38a, 38b. The air passageway connects the region beneath the device 20 below planar lower surface 35 to the region rearwards of the device 20.

The configuration of the contaminant separation device 20 will now be described in more detail with reference to Figure 6, which shows a cross-section of the device 20 taken across the plane A-A-A in Figure 4. In the following description, reference is made to the top and bottom of the device 20. These terms should be understood to correspond to the usual orientation of the contaminant separation device 20 in use, as shown in Figure 4.

The planar lower surface 35 of the device 20 is generally defined by a pair of substantially horizontal, approximately coplanar plates 40, 42 that extend across the width of the device 20, between the two sidewalls. The foremost plate 40 (referred to as the primary plate) is part of the body portion 34 of the device 20; and the rearmost plate 42 (referred to as the secondary plate) is part of the mounting portion 36 of the device 20. The two plates 40, 42 are spaced apart such that an opening or inlet 44 is defined between the plates 40, 42. The inlet 44 is defined across the width of the device 20 such that the inlet 44 takes the form of an elongate slot extending across the width of the planar lower surface 35 of the device 20 (i.e. in a direction transverse to the direction of the inlet flow).

The body portion 34 further comprises an upper plate 46, approximately parallel to the primary and secondary plates 40, 42, which partly defines the upper profile of the device 20. The foremost edge 46a of the upper plate 46 smoothly transitions into a sloping section 48, extending diagonally downwards and forwards from the foremost edge 46a of the upper plate 46 to the front of the device 20. The sloping section 48 is smoothly connected to the foremost edge 40a of the primary plate 40 by a curved nose region 50.

Turning now to the mounting portion 36 of the device 20, a baffle plate 52 extends from the foremost edge 42a (nearest the inlet 44) of the secondary plate 42. The baffle plate 52 projects diagonally upwards and forwards from the secondary plate 42, towards the sloping section 48 of the body portion 34. The baffle plate 52 comprises three sections 52a, 52b, 52c of successively decreasing length. Each section 52a, 52b, 52c has a different gradient, with the middle section 52b having the shallowest gradient. Accordingly, the baffle plate 52 has a roughly S-shaped or kinked profile.

In addition, the mounting portion 36 comprises an attachment region 54, the foremost edge 54a of which abuts the rearmost edge 46b of the upper plate 46 of the mounting portion 36. In order to allow the contaminant separation device 20 to be attached to the front end carrier 24, the attachment region 54 of the mounting portion 36 defines tabs 56 (best seen in Figure 4) that project rearwards and outwards from the device 20. These tabs 56 are appropriately sized and shaped to cooperate with the front end carrier 24. As such, the attachment region of the mounting portion 36 receives a foremost portion of the front end carrier 24 and the tabs 56 rest against the top and front surfaces of the front end carrier 24.

The tabs 56 include through-holes 58 that permit a scrivet fastener to be inserted through them to attach the contaminant separation device 20 to the front end carrier 24. In other embodiments, the contaminant separation device 20 may be attached to the front end carrier 24 by bolts, clips or any other appropriate means. The rearmost edge 42b of the secondary plate 42 is also suitably adapted to accommodate the foremost edge of the front end carrier 24. Thus, the mounting portion 36 is appropriately adapted so that the contaminant separation device 20 can be attached to the front end carrier 24.

The function of the contaminant separation device 20 will now be described in more detail with reference to Figure 7 which shows a cross-section of the contaminant separation device 20 in situ within the air induction system 12 of the vehicle 10.

The air induction system 12 defines two separate air passageways or flow-paths: a contaminated flow-path 60 which leads to the vehicle radiator and a clean flow-path 62 which leads to the air ducts 22. Generally, the role of the contaminant separation device 20 is to allow clean air to pass along the clean flow-path 62 and direct contaminants along the contaminated flow-path 60 in order to prevent them from entering the air ducts 22. The direction of airflow along these flow-paths 60, 62 is indicated by arrows in Figure 7.

Figure 7 shows the exterior intake port 14 disposed on the front end of the vehicle 10, below the bonnet 30. As described above, air is drawn into the exterior intake port 14 from outside the vehicle 10 through the protective grille 32. The profile of the nose region 50 of the contaminant separation device 20, behind the grille 32, directs the drawn-in air underneath the device 20.

Air passing beneath the device 20 tends to attach to the lower surfaces 40c, 42c of the primary and secondary plates 40, 42. Therefore, the horizontal (or near-horizontal) plates 40, 42 constitute a guidance means that induces a laminar flow of air beneath the device 20 from right to left (in the configuration shown in Figure 7). Inducing a laminar flow in this way reduces undesirable air turbulence when air is drawn through the air induction system 12 and reduces the flow of contaminants into the air ducts 22 of the induction system 12, as will be described.

The laminar flow defines the contaminated flow-path 60 which by-passes the air ducts 22. Rearwards of the secondary plate 42, the contaminated flow-path 60 leads to the engine radiator. The contaminated air is used for engine cooling which is not adversely affected by contaminants within the cooling airflow.

The inlet 44 between the primary and secondary plates 40, 42 defines the entrance of the clean flow-path 62. Air from the laminar flow beneath the device 20 is sucked through the inlet 44 into the clean flow-path 62 by the action of the engine 18. However, contaminants are prevented from entering the clean flow-path 62 due to their comparatively large inertial mass in relation to the air particles. Contaminant particles in the drawn-in air are more inclined to continue on their path along the contaminated flow-path 60 towards the engine radiator. In addition, air enters the inlet 44 at an angle substantially perpendicular to the direction of the laminar flow, i.e. vertically upwards. Therefore, the mass of the contaminant particles acts to prevent the contaminants entering the clean flow-path 62.

The position of the inlet 44 in front of the dirty side air-ducts and its geometry, particularly the fact that the inlet extends across a large proportion of the width of the vehicle, are conducive to inducing a homogenous air flow across the inlet. This reduces the air flow velocity and therefore reduces the possibility of contaminants being drawn into the clean flow-path.

Thus, contaminants are swept past the inlet 44, whereas cleaner air is dragged through, into the clean flow-path 62. Accordingly, air entering the clean flow-path 62 contains fewer contaminants than the air as originally drawn-in through the exterior intake port 14. Thus, clean air is diverted from the laminar flow beneath the device 20 and dragged into the clean flow-path 62 from where it is permitted to reach the air ducts 22.

It is possible that some contaminants will be dragged through the inlet 44 and enter the clean flow-path 62. Therefore, the passage 39 defined by the contaminant separation device 20 is configured such that the baffle plate 52 directs air along a path that reduces the likelihood of contaminants entering the air ducts 22. For example, the direction of the path along which air travels along the passage 39 through the contaminant separation device 20 is meandering and turns back on itself. Along a first portion 39a of the passage 39, air is directed in a direction opposite to the direction of the laminar flow beneath the device 20. A second portion 39b of the clean flow-path 62 is substantially parallel to the direction of the laminar flow. In other words, the direction of airflow along the passage 39 is substantially reversed. Varying the direction of the airflow increases the likelihood that the inertia of the contaminant particles will cause them to be swept out of the airflow. Contaminants may therefore collect within the concave inner profile of the nose region 50 of the device 20, for example.

Air exiting the contaminant separation device 20 enters the air ducts 22 via the air duct carrier 26. Any remaining contaminant particles that do enter the air ducts 22 are prevented from entering the intake manifold 16 by the air cleaners 28.

As a result of the configuration of the air induction system 12 (including a contaminant separation device 20 according to an embodiment of the invention), the vehicle 10 is permitted to travel increased distances, even in conditions in which the ambient air contains high levels of contaminants.

The skilled person will appreciate that many modifications may be made to the above examples without departing from the scope of the present invention as defined in the accompanying claims.

Claims

1. A contaminant separation device for a vehicle air induction system comprising; a planar lower surface configured to induce and/or maintain lamination in contaminated air flow beneath it, an inlet situated in the lower surface to allow air to flow from below the surface to above the surface; such that heavier particles remain within the contaminated air flow.

2. The contaminant separation device according to claim 1, wherein the inlet is an elongate slot in the lower surface which extends across the width of the device, transverse to the direction of the laminar flow, positioned to separate the lower surface into two coplanar surfaces.

3. The contaminant separation device according to any preceding claim wherein the inlet has a front edge and a rear edge, the front edge disposed towards the front of the vehicle and the rear edge disposed towards the back of the vehicle, the rear edge having a flow guidance means extending upwards from the lower surface in the direction of the air flow.

4. The contaminant separation device according to claim 3, wherein the flow guidance means extends diagonally upwards and forwards.

5. The contaminant separation device according to claim 3 or 4, wherein the intersection between the lower surface and the flow guidance means is a radiused edge.

6. The contaminant separation device according to claim 3, 4 or 5, wherein air is directed towards the air induction system along a passage at least partially defined by the flow guidance means.

7. The contaminant separation device according to any preceding claim, wherein the planar lower surface is substantially horizontal.

8. The contaminant separation device according to any preceding claim, wherein the device is configured such that air enters the inlet at an angle to the direction of the laminar flow of contaminated air.

9. The contaminant separation device of Claim 8 wherein the device is configured such that air enters the inlet substantially perpendicular to the direction of the laminar flow.

10. The contaminant separation device according to any preceding claim, wherein the device comprises an aerodynamic feature for directing contaminated air underneath the device.

11. An air induction system for a vehicle comprising the contaminant separation device according to any preceding claim.

12. A method for extracting clean air from a contaminated air flow in a vehicle air induction system comprising; inducing laminar flow of the contaminated air beneath a planar surface, extracting clean air from the laminar flow from beneath the surface to above the surface through an inlet in the surface.

13. A vehicle comprising the engine air induction system of Claim 11.

14. The vehicle of Claim 13 wherein the vehicle comprises a radiator and contaminants from the laminar flow beneath the contaminant separation device is directed to the radiator having by-passed the inlet.

15. The vehicle of Claim 13 or Claim 14 wherein the vehicle includes a grille disposed at the front end of the vehicle and the contaminant separation device is fitted behind the grille.

16. A contaminant separation device as herein described with reference to the accompanying figures.

17. A vehicle engine air induction system as herein described with reference to the accompanying figures.

18. A vehicle as herein described with reference to the accompanying figures.