GB2620733A

GB2620733A - A vehicle emissions sampling device for sampling emissions from a wheel and/or brake of a vehicle

Info

Publication number: GB2620733A
Application number: GB2210310.5A
Authority: GB
Inventors: Molden Nick
Original assignee: Emissions Analytics Ltd
Current assignee: Emissions Analytics Ltd
Priority date: 2022-07-13
Filing date: 2022-07-13
Publication date: 2024-01-24
Also published as: WO2024013495A1; GB202210310D0

Abstract

A sampling device for sampling emissions from a wheel 5, tyre and/or brake of a vehicle, comprises: a mounting hub 12 attachable to a wheel of a vehicle; a sampling tube 20 rotatably mounted to the mounting hub such that the sampling tube extends to a position adjacent to the wheel of the vehicle, and a holding assembly 52, 46, 48 attachable to the vehicle and arranged to restrict rotation of the sampling tube 20 relative to the mounting hub. Tubing 32 connects the sampling tube 20, which is perforated, to a particle analyser. The sampling device can be used on steered wheels and maintains the sampling tube in a constant position relative to the wheel. The mounting hub is a interchangeable mounting plate attachable with wheel nuts.

Description

A VEHICLE EMISSIONS SAMPLING DEVICE FOR SAMPLING EMISSIONS FROM A

WHEEL AND/OR BRAKE OF A VEHICLE [0001] This invention relates to a vehicle emissions sampling device for sampling emissions from a wheel and/or brake of a vehicle.

BACKGROUND

[0002] Existing devices for monitoring tyre emissions are mounted to the vehicle body, for example the chassis of the vehicle, and are designed to measure tyre emissions from non-steered wheels as the device is in a fixed position relative to the vehicle. When applied to steered wheels, prior art sampling devices are unable to reliably measure tyre emissions when steering as the distance between the device and the wheel will change depending on the steering angle of the wheel, and emissions may not be directed towards the device, or detected by the device. Prior art devices can therefore only reliably measure tyre emissions in controlled settings, such as on rollers in an indoor facility where steering is not required.

Such measurements have limited applicability to real-world driving conditions, where driving conditions and road conditions can greatly affect tyre emissions.

BRIEF SUMMARY OF THE DISCLOSURE

[0003] Viewed from a first aspect, the present disclosure provides a vehicle emissions sampling device for sampling emissions from a wheel and/or brake of a vehicle, in particular a car. The vehicle emissions sampling device comprises: a mounting hub attachable to the wheel of the vehicle; a sampling tube rotatably mounted to the mounting hub such that the sampling tube extends to a position adjacent to the wheel of the vehicle, and a holding assembly attachable to the vehicle and arranged to restrict rotation of the sampling tube relative to the mounting hub.

[0004] Thus, the present disclosure provides a device which enables monitoring of tyre and/or brake emissions during real-world driving conditions. The device can be used to provide a more realistic assessment of tyre and/or brake emissions which can be used as part of the vehicle design process and also in the certification process that particular vehicles meet certain particulate emissions standards.

[0005] The sampling tube may comprise a rotary portion rotatably mounted to the mounting hub. The holding assembly may be attachable to a body panel of the vehicle. The holding assembly may comprise a suction cup for attaching to the body panel of the vehicle. The holding assembly may be coupled to the sampling tube, for example, at the rotary portion or at a position along the length of the sampling tube. The holding assembly may be coupled to the sampling tube at a first end and attachable to the vehicle at a second end.

[0006] The holding assembly may comprise a first strut having a first end coupled to the sampling tube. The holding assembly may comprise a second strut having a first end attachable to the vehicle. The second strut may be coupled to the first strut. The second strut may have a second end coupled to the first strut. The first strut may be coupled to the vehicle via the second strut.

[0007] The wheel may be a steered wheel (e.g., a front wheel of the vehicle). The sampling tube may be arranged to rotate relative to the mounting hub about a first axis aligned with the rotational axis of the wheel. The first strut and the second strut may be coupled such that the first strut can move relative to the second strut when the wheel is steered. This advantageously prevents rotation of the sampling tube while allowing the wheel to be steered. The coupling between the first and second struts permits the angle of the first strut to vary to accommodate the arcuate movement of the first end as the wheel is steered due to the movement of the first end of the first strut moves about an arc defined by the steering axis of the steered wheel. The coupling may permit sliding. This advantageously allows for the position of the second strut to be fixed while the first strut moves as the wheel is steered.

[0008] The second end of the second strut may comprise an eyelet for coupling to the first strut. The eyelet allows sliding of first strut relative to the second strut while limiting rotation of the first strut about the rotational axis of the wheel. The eyelet advantageously allows enough rotation to accommodate the steering action, while also preventing the sampling tube attached to the first strut from freely rotating about the rotational axis of the wheel.

[0009] The holding assembly may comprise a third strut coupled to the second strut and having a first end attachable to the vehicle.

[0010] The second strut may be arranged to restrict movement of the first strut in a first direction. The third strut may be arranged to restrict movement of the first strut in a second direction. The third strut may have an adjustable length. One or more of the first strut and the second strut may have an adjustable length. The first direction may be parallel with a longitudinal axis of the second strut. The second direction may be parallel with a longitudinal axis of the third strut.

[0011] The device may comprise tubing fluidly connected to the sampling tube, and connectable to an analyser for analysing particulate emissions received in the sampling tube. A portion of the tubing may pass through an internal channel of the first strut. The device may comprise an analyser for monitoring emissions fluidly coupled to the sampling tube.

[0012] The sampling tube may comprise a plurality of perforations for receiving particulate emissions from the wheel and/or brake. The sampling tube may comprise a first section extending from the mounting hub in a first direction and a second section extending from the first section at an angle relative to the first section such that, in use, the second section is positioned adjacent to a road-contacting surface of the wheel. The second section may be selectively positioned behind the wheel at a position determined by a user. The sampling tube may have an adjustable length. The first section may have an adjustable length. This advantageously allows for the sampling tube to be used to measure emissions from vehicles having different wheel diameters. The second section may comprise one or more perforations for receiving particulate emissions from the wheel and/or brake.

[0013] The mounting hub may be attachable to the wheel by one or more wheel nuts. The mounting hub may comprise an interchangeable mounting plate having holes for mounting to the wheel by the one or more wheel nuts. An interchangeable mounting plate advantageously allows for the vehicle emissions sampling device to be used with different wheels having different wheel nut sizes and arrangements.

[0014] The vehicle emissions sampling device may further comprise a suction device operable to apply suction to the sampling tube. In some cases, the emissions sample is collected in a sample collector for later analysis. In some cases, there is more than one sample collector for distributing the collected samples between the multiple sample collectors. In some cases, the device may only collect the samples for later analysis.

[0015] The vehicle emissions sampling device may further comprise an analyser for analysing particulate emissions received in the sampling tube. The analyser may detect one or more parameters of the particulate emissions, for example any combination of particle size, particle type, and chemical composition. The analyser may detect the or each parameter as an instantaneous value (i.e., continuously). The analyser may record variations in the detected parameters over time. The analyser may additionally include a sample collector for collecting the sample after it has been analysed, or to collect a portion of the sample (the rest being analysed). Therefore, instantaneous parameters can be detected, and the collected sample may be subject to further analysis at a later date (e.g., in a laboratory). The vehicle emissions sampling device may further comprise a controller configured to record telemetry data of the vehicle. Telemetry data can include vehicle speed, vehicle acceleration, vehicle deceleration, brake pressure, vehicle location. In some cases, a GPS unit may be operatively connected to the controller. The controller may map detected parameters and the vehicle telemetry, for example based on time.

[0016] There is also provided a method of measuring emissions from a wheel and/or brake of a vehicle, the method comprising: mounting a vehicle emissions sampling device as described above to the wheel and/or brake of the vehicle via the mounting hub, such that the sampling tube is positioned adjacent to the wheel of the vehicle, and measuring emissions from the wheel and/or brake of the vehicle while driving the vehicle.

[0017] The method may comprise mounting the vehicle emissions sampling device to a steered wheel of the vehicle (e.g., a front wheel of a car) and steering the steered wheel while measuring emissions from the steered wheel and/or a brake associated with the steered wheel. Driving the vehicle may comprise driving the vehicle on a road. Mounting the device may comprise adjusting the length of the sampling tube such that the sampling end is a pre-determined distance from a surface of a tyre of the wheel.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Embodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which: Figure 1 is a schematic representation of a vehicle having a device for sampling emissions from a wheel of the vehicle; Figure 2 is an illustration of the mounting hub to attach the device to the wheel of the vehicle; Figure 3 illustrates a side view of the device mounted to the wheel of the vehicle; Figure 4 illustrates the sampling tube behind the wheel; Figure 5 is an illustration of a holding assembly used to hold the sampling tube in position behind the wheel, and Figure 6 illustrates an analyser for measuring emissions from the wheel. DETAILED DESCRIPTION [0019] Figure 1 is a schematic representation of a vehicle 1 having a vehicle emissions sampling device 10 for sampling emissions, in particular particulate emissions, from a wheel 5 and/or brake (not shown) of the vehicle 1. The vehicle 1 is a car. However, it would be apparent that the present device 10 can be used with any vehicle having wheels, both steered and non-steered, as are typically found on vans, trucks, lorries and motorcycles. As the wheel passes over the road surface, particulates are emitted from the wheel (e.g. the tyre) and/or brake which can be monitored by the device 1. The device 10 is shown mounted to a steered wheel 5 (front wheel), but it would be apparent that this was not essential, and the device 10 is equally suitable for mounting to non-steered wheels 7 (rear wheels). Tubing 32 is used to pass the sampled emissions from the device 10 to an analyser 9 which applies a vacuum through the device to draw detected emissions into the analyser 9 for identifying the emissions in a known manner. It would be apparent that a separate suction device may be coupled to the tubing 32 independently of the analyser 9 for drawing emissions samples through the sampling tube for later analysis.

[0020] The device 10 includes a mounting hub 12 for attaching the device 10 to the wheel 5 of the vehicle 1. In the illustrated example, the mounting hub 12 includes a mounting plate 14 which is secured to the wheel 5 using wheel nuts 16 as shown in Figure 2. This allows the mounting hub 12 to rotate about the same rotating axis as the wheel 5. The mounting plate is preferably interchangeable (i.e. removably connected to the sampling tube 20) so the device 10 can be mounted to different wheels via a corresponding mounting plate 14 which may have a different arrangement of holes to account for the different arrangement of wheel nuts holes in different wheels. The device 10 includes a sampling tube 20 connected to the wheel hub 12 for receiving particulate emissions from the wheel 5. A rotary portion 17 connects the mounting hub 12 to the sampling tube 20 and allows the mounting hub 12 to rotate relative to the sampling tube 20. The rotary portion 17 may include a bearing or bushing to rotatably mount the sampling tube 20 to the housing hub 12. This is particularly advantageous, as the sampling tube 20 is kept in a relatively fixed position relative to the wheel 5 as the wheel rotates 5. Thus, the present device 10 can be used when driving in real-world conditions as explained below [0021] Figure 3 illustrates a side view of the device 10 mounted to the steered wheel 5, with parts of the device 1 omitted for clarity. As shown in Figure 3, the sampling tube 20 is connected to the mounting hub 12 via the rotary portion 17 at one end and extends radially from the centre of the wheel 5 to behind the wheel 5 to measure particulate emissions from the wheel 5.

[0022] With reference to Figure 4, the sampling tube 20 includes a first section 22 having a first end coupled to the mounting hub 12, and a second end connected to a second section 24. The second section 24 includes a sampling end 26 which has perforations formed therein for receiving particulate emissions from the wheel 5. The perforations are shown distributed around the circumference of the sampling end 26, but it would be apparent this was not essential. The second section 24 is shown as an L-shaped tube, but it would be apparent this was not essential. In some cases, the second section need only terminal adjacent the wheel 5 (i.e. be spaced from the wheel in a lateral direction relative to the direction of travel of the vehicle 1). In the illustrated example, the second section is positioned adjacent to a road-contacting surface of the wheel 5. In the illustrated example, at least part of the second section 24 is received within the first section 22 such that the second section 24 is telescopically mounted to the first section 22. A releasable connector 28 allows the second section 24 to slide relative to the first section 22 which lets a user easily adjust of the overall length of the sampling tube 20. The present device 10 can therefore be mounted to a range of wheel sizes, providing improved utility of the device 10. A further advantage of the adjustable sampling tube 20 is that the sampling distance from the tyre can be kept the same between different vehicles, for example to allow for better comparisons between emissions from different vehicles, or to account for wear of a given tyre which would affect the measured emissions. The sampling tube 20 preferably comprises metal tubing, such as steel tubing. While the device 10 is described in relation to sampling tyre emissions, the present device 10 can also be used to measure particulate emissions from the brake(s) of the vehicle 5. In one example, the sampling tube 20 can be positioned close to the wheel centre and adjacent the brake pads (not shown), as opposed to adjacent the road surface as shown in Figure 4. Alternatively or additionally, the sampling tube 20 may have multiple sampling ends 26 for sampling tyre emissions and brake pad emissions simultaneously or sequentially. The sampling tube 20 may have a second section 24 which wraps around the wheel 5 (for example having a U-shaped profile). In this case, the second section 24 may include perforations at multiple locations on the second section 24, for example at a similar location is to that shown in Figure 4 to measure tyre emissions, but also along the portion of the second section 24 adjacent the brake pad (not shown) so that brake pad samples can be collected independently of the tyre emissions.

[0023] With reference to Figures 1 to 3 and 5 and 6, the internal cavity of the sampling tube 20 is fluidly connected to tubing 32 which extends to the analyser 9. This provides a fluid flow path between the sampling end 26 and the analyser 9. It would be apparent that where the analyser 9 is sufficiently portable, it could be connected directly to the sampling tube 20, for example by being mounted to the mounting hub 12 or contained within the mounting hub 12, which would allow for the tubing 32 to be omitted. However, where the analyser 9 is too large for such an arrangement and needs to be located in the vehicle, e.g. in the boot as shown in Figure 1, tubing 32 can be used to provide a fluid flow path from the sampling tube 20 to the analyser 9.

[0024] As the present device 10 is designed for real-world driving, i.e. where the steered wheel 5 will be steered as the vehicle is driven, it is preferable to secure the tubing 32 to the vehicle 5. This can be achieved using a holding assembly 40 as explained below.

[0025] With reference to Figures 2, 3 and 5, a holding assembly 40 is provided to couple the sampling tube 20 to the vehicle, so that the sampling end 26 is kept in the correct position relative to the wheel 5. Where present, the holding assembly 40 can also secure the tubing 32 to the vehicle 1. In the illustrated example, the holding assembly 40 includes multiple struts 42, 44, 52 for holding the sampling tube 20 and tubing 32 in position. A first strut 52 is connected to the mounting hub 12 at one end and is coupled to the vehicle 1 at a second end. This restricts the rotation of the sampling tube 20 relative to the wheel 5 about the rotating axis Al of the wheel 5 and mounting hub 12. While the first strut 52 is pivotally connected to the mounting hub 12 such that the first strut 52 can rotate away from the vehicle about a pivot point on the mounting hub 12 (see Figure 2) it would be apparent this was not essential. A second end of the first strut 52 is coupled to the vehicle 1 to hold the sampling tube 20 in position. As illustrated in Figure 3, this can be achieved by coupling the second end of the first strut 52 to a second strut 42 attached to the vehicle 1. However, it would be apparent the first strut 52 may be attached to the vehicle 1 directly to hold the sampling tube 20 in position.

[0026] In the illustrated example, the second strut 42 is attached to the bonnet 4 of the vehicle 1 by a suction cup 44 and extends in a substantially lateral direction relative to a longitudinal axis of the vehicle 1. The first strut 52 and second strut 42 are coupled to one another by an eyelet 50 and the first strut 52 extends through the eyelet 50. This allows the first strut 52 to translate along its longitudinal axis A2, while restricting movement of the first strut 52 along the longitudinal axis of the second strut 42. When the wheel 5 is steered the first end of the first strut 52 moves about an arc defined by the steering axis of the steered wheel (parallel to axis A2). The coupling 50 between the first 52 and second 42 struts permits the angle of the first strut 52 to vary to accommodate the arcuate movement of the first end as the wheel 5 is steered. The first strut 52 is also able to slide through the eyelet 50. In the illustrated example, the position of the second strut 42 is fixed, and the first strut 52 moves when the wheel 5 is steered. The second strut 42 is arranged to hold the first strut 52 in a substantially vertical orientation A2 relative to the ground (i.e. perpendicular to the rotating axis Al of the wheel). This allows the wheel 5 to rotate freely about its rotational axis Al and also allows the wheel to steer about its steering axis which is parallel to axis A2 and also to travel in a direction parallel to A2 (e.g. to accommodate vertical wheel travel due to the suspension of the vehicle 1). It would be apparent that the second strut 42 was not essential, as the first strut 52 could be attached to the vehicle directly in a substantially vertical orientation to allow the wheel 5 to rotate about axis Al and translate along A2 as described above. As shown in Figure 5, a cable 30 wound around the first strut 52 provides a secondary way of coupling the first strut 52 to the vehicle 1 to hold the first strut 52 in the required position. As shown in Figure 2, a buckle 56 can be used to secure an end of the cable 30 to the mounting hub 12, but it would be apparent this was not essential. However, the cable 30 is not essential and may be omitted entirely. While suction cups 44, 48 are preferred as they allow for attachment of the device 10 to any vehicle, it would be apparent this was not essential.

[0027] Where the second strut 42 is rotatably mounted to the suction cup 44, the third strut 46 (omitted from Figure 3 for clarity) can be coupled to the second strut 42 to restrict movement of the second strut 42 in a second direction (e.g. parallel to a longitudinal axis of the third strut 46). As shown in Figure 5, a clamp 54 can be used to couple the second strut 42 to the third strut 46, but it would be apparent this was not essential and other connectors or couplings could be used. As the third strut 46 is attached to a door panel 2 and extends in a substantially parallel direction to the longitudinal axis of the vehicle 1, this restricts the movement of the second strut 42 in the longitudinal direction of the vehicle 1. Thus, by orienting the second strut 42 at an angle relative to the third strut 46, for example a substantially perpendicular angle, it is possible to limit the rotation of the first strut 52 relative to the vehicle 1 about axis Al (so it remains substantially vertical as the wheel 5 rotates) while allowing for rotation of the first strut 52 about its longitudinal axis A2 which is parallel to the steering axis of the wheel 5 (which accounts for the steering angle of the wheel 5). Any of the first strut 52, the second strut 42 and/or the third strut 46 may be tubular to provide an internal passage. Any of the first strut 52, the second strut 42 and/or the third strut 46 may have an adjustable length, for example by including one or more telescopic sections is which can slide within the respective internal passage of the struts 52, 42, 46.

[0028] The holding assembly 40 provides a convenient structure for routing the tubing 32 from the sampling tube 20 to the analyser 9. However, it would be apparent that tubing 32 need not be connected to the holding assembly 40 at all. By way of example and with reference to Figures 1 to 3 and 5, tubing 32 extends from the sampling tube 20 to the first strut 52 and enters the first strut 52 through an opening in a side wall of the first strut 52. As the first strut 52 is tubular (i.e. is formed as a hollow tube), the tubing 32 can pass through the internal passage of the first strut 52 before exiting through the end of the first strut 52. The tubing 32 is secured to the second strut 42 such that the tubing 32 extends along a portion of the second strut 42. The tubing 32 extends along the windscreen of the vehicle and into the vehicle cabin before being connected to an inlet port of the analyser 9 in the boot as shown in Figure 6 for analysing the particulate emissions in a known manner.

[0029] A particulate analyser, such as an Electrical Low Pressure Impactor, ELPI+ (RTM) analyser made by Dekati (RTM), would be suitable for use with the device 10. Such an analyser 9 contains a series of plates (for example 14 plates) that coiled successively finer particles from coarse to ultra-fine. Samples can be captured on greased substrates and analysed for both structural and chemical properties. An ELPI analyser is a particle size spectrometer for real-time particle measurements which can measure real-time particle size distribution and concentration in the size range of 6 nm -10 pm at a 10 Hz sampling rate.

[0030] The present device 10 enables dynamic tyre wear particulate monitoring, as different tyre wear parameters can be correlated with real-world road conditions. For example, a user can drive on a public road and overlay instantaneous levels of tyre emissions data with a map of the route. This can provide a more realistic measure of tyre emissions, as road conditions (e.g. road surface conditions, turning points) and driving conditions (e.g. vehicle speed, accelerating, braking) can be taken into account when assessing tyre emissions. By way of example, the analyser can provide real-time data on particulate mass vs. time or particle number vs. time for a given route. Particulate emission data may also be correlated with other telemetry data of the vehicle, for example obtained by a GPS unit operatively connected to the analyser 9. In some cases, the analyser 9 can include multiple collectors and the emissions samples may be distributed between the containers based on particular telemetry data (e.g., emissions collected when acceleration is greater than a threshold are collected in a first collector, while emissions collected when travelling above a certain speed can be collected in a second collector). The present device 10 has been used to quantify high tyre emissions during acceleration, deceleration and cornering events, but also correlating with certain road surfaces. A further finding is that tyre emissions are higher at the start of the test, which may indicate tyre emissions may be higher is when the surface of the tyre is cooler. The present device 10 has also allows for vehicle speed to be correlated with particulate mass and particulate size which has shown that during high load events, such as acceleration and cornering, the tyres are primarily emitting smaller particles, and even in low-load driving ultrafine particles are emitted.

[0031] Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of them mean "including but not limited to", and they are not intended to (and do 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.

[0032] Features, integers, characteristics, 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. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

CLAIMS1. A vehicle emissions sampling device for sampling emissions from a wheel and/or brake of a vehicle, the device comprising: a mounting hub attachable to the wheel of the vehicle; a sampling tube rotatably mounted to the mounting hub such that the sampling tube extends to a position adjacent to the wheel of the vehicle, and a holding assembly attachable to the vehicle and arranged to restrict rotation of the sampling tube relative to the mounting hub.
2. The vehicle emissions sampling device according to claim 1, wherein the sampling tube comprises a rotary portion rotatably mounted to the mounting hub.
3. The vehicle emissions sampling device according to claim 1 or claim 2, wherein the holding assembly is attachable to a body panel of the vehicle.
4. The vehicle emissions sampling device according to claim 3, wherein the holding assembly comprises a suction cup for attaching to the body panel of the vehicle.
5. The vehicle emissions sampling device according to claim 3 or 4, wherein the holding assembly is coupled to the sampling tube.
6. The vehicle emissions sampling device according to any of claims 3 to 5, wherein the holding assembly is coupled to the sampling tube at a first end and attachable to the vehicle at a second end.
7. The vehicle emissions sampling device according to any preceding claim, wherein the holding assembly comprises: a first strut having a first end coupled to the sampling tube, and a second strut having a first end attachable to the vehicle and a second end coupled to the first strut, wherein the first strut is coupled to the vehicle via the second strut.
8. The vehicle emissions sampling device according to claim 7, wherein the wheel is a steered wheel, wherein the sampling tube is arranged to rotate relative to the mounting hub about a first axis aligned with the rotational axis of the wheel, and wherein the first strut and the second strut are coupled such that the first strut can move relative to the second strut when the wheel is steered.
9. The vehicle emissions sampling device according to claim 7 or 8, wherein the second end of the second strut comprises an eyelet for coupling to the first strut.
10. The vehicle emissions sampling device according to any of claims 7 to 9, wherein the holding assembly comprises a third strut coupled to the second strut and having a first end attachable to the vehicle.
11. The vehicle emissions sampling device according to claim 10, wherein the second strut is arranged to restrict movement of the first strut in a first direction, and wherein the third strut is arranged to restrict movement of the first strut in a second direction.
12. The vehicle emissions sampling device according to claim 10 or 11, wherein the third strut has an adjustable length.
13. The vehicle emissions sampling device according to any of claims 7 to 12, wherein one or more of the first strut and the second strut has an adjustable length.
14. The vehicle emissions sampling device according to any preceding claim comprising tubing fluidly connected to the sampling tube, and connectable to an analyser for analysing particulate emissions received in the sampling tube.
15. The vehicle emissions sampling device according to claim 14 when dependent on any of claims 7 to 13, wherein a portion of the tubing passes through an internal channel of the first strut.
16. The vehicle emissions sampling device according to any preceding claim, wherein the sampling tube comprises a plurality of perforations for receiving particulate emissions from the wheel and/or brake.
17. The vehicle emissions sampling device according to any preceding claim, wherein the sampling tube comprises a first section extending from the mounting hub in a first direction, and a second section extending from the first section at an angle relative to the first section such that, in use, the second section is positioned adjacent to a road-contacting surface of the wheel.
18. The vehicle emissions sampling device according to any preceding claim, wherein the sampling tube has an adjustable length.
19. The vehicle emissions sampling device according to any preceding claim, wherein the mounting hub is attachable to the wheel by one or more wheel nuts.
20. The vehicle emissions sampling device of claim 19, wherein the mounting hub comprises an interchangeable mounting plate having holes for mounting to the wheel by the one or more wheel nuts.
21. The vehicle emissions sampling device according to any preceding claim, further comprising a suction device operable to apply suction to the sampling tube.
22. The vehicle emissions sampling device according to any preceding claim, further comprising an analyser for analysing particulate emissions received in the sampling tube.
23. A method of measuring emissions from a wheel and/or brake of a vehicle, the method comprising: mounting a vehicle emissions sampling device according to any preceding claim to the wheel of the vehicle via the mounting hub, such that the sampling tube is positioned adjacent to the wheel of the vehicle, and measuring emissions from the wheel and/or brake of the vehicle while driving the vehicle.
24. The method according to claim 23, comprising mounting the vehicle emissions sampling device to a steered wheel of the vehicle and steering the steered wheel while measuring emissions from the steered wheel and/or a brake associated with the steered wheel.
25. The method according to claim 23 or 24, wherein driving the vehicle comprises driving the vehicle on a road.