Vehicle equipped with a device for collecting tire wear particles

Abstract

Vehicle (1) equipped with at least one device (2) for collecting tire wear particles (3), at least one air bypass device (21) comprising an air inlet (211), a duct (212), an air outlet (213) and a particle collector (24), the air inlet (211) is disposed on the vehicle and configured to collect air (4) having a velocity at the level of the air inlet (211) at least equal to 30% of the speed of the vehicle (1). The duct (212) carries the air to the air outlet (213), the air outlet (213) of the device (2), and the particle collector (24) is axially posterior to the rear end of the contact area (322) of the tire (3) and axially posterior to the air inlet (211) and is designed to collect a portion of the airflow (51) directed by the air outlet (213). (See Figure 1 for an abstract diagram.)

Description

Title of the invention: Vehicle equipped with a device for collecting tire wear particles

[0001] This document relates to a motor vehicle comprising at least one air bypass device, to improve the capture of wear particles and other dust passing near the rolling surface of the tires by optimizing the airflow around the wheel to reduce the dispersion of tire wear particles into the environment.

[0002] During driving, tires wear down. The repeated stresses applied to the tire tread inevitably cause pieces of rubber to tear off. Sometimes these pieces are the tread itself, in which case it is collected by road cleaning crews. However, this type of incident is rare given the number of vehicles on the roads. More often than not, especially for vehicles designed to travel on paved roads such as personal or company cars, buses, coaches for passenger transport, and trucks for freight transport, their tires wear down regularly with the number of kilometers traveled, more or less rapidly depending on the driver's style and the levels of braking or engine torque that said driving entails.This wear also depends on lateral stresses, most often related to the type of road, whether it's straight or curved, with or without roundabouts. The particles torn from the tread during these uses vary in size, from millimeters and possibly down to nanometers. Particles of this size are generally not collected and end up in roadside soils or other ecosystems, transported by runoff. It is estimated that 1,320,000 tons of particles are produced each year in the European Union (2018, Wagner et al. PMID 29631188) due to transportation. These small particles are not collected by road maintenance services because of their small size. They should be collected before they disperse into the environment, preferably by the vehicle that emits them.

[0003] In order to reduce brake dust emissions in particular, techniques are known such as, for example, protective devices, blowers, and dust collectors. For example, DE 20 2007 000 246 U1 describes a brake dust collector in which a fan generates an airflow that carries the brake dust that has formed towards a filter element. The filter element may be of electrostatic construction, in order to improve collection by The electrostatic accretion of dust particles. The fan blades can be made from wheel spokes. However, this solution is not suitable for reducing particle emissions from tire wear.

[0004] CN 2 052 369 U discloses a motor vehicle comprising a dust trap, disposed downstream of a tire of the vehicle, with an air inlet opening located below, into which enters some of the air laden with dust detached from the tire during movement.

[0005] To improve this device, JP 2008302803 A proposes a collector equipped with a fan that creates suction at the rear of the tire to draw in the particles. This interesting solution is not entirely satisfactory, however, because it requires the installation of an electric motor whose power consumption is supplied by the vehicle's central engine or battery, thus reducing its range. Furthermore, it increases the vehicle's weight. Moreover, such a device requires energy consumption that increases exponentially with vehicle speed. Indeed, as the vehicle speed increases, the speed of the airflow along the vehicle increases, and the more particles tend to be drawn out of the wheel arch by this airflow. To compensate for this suction, the fan of the device must increase its own speed and therefore its energy consumption.

[0006] The inventor has set himself the objective of significantly improving the operation of a device for collecting particles, in particular tire wear particles located downstream of the tire, while minimizing the energy consumed.

[0007] This objective is achieved by a vehicle equipped with at least one device for collecting wear particles from at least one tire, the vehicle having a main driving direction (XX') designated as the axial direction, a transverse direction (YY') and a vertical direction (ZZ') perpendicular to the axial direction, comprising: • each tire having a maximum width measured in the direction of the tire's axis of rotation, comprising a tread including a tread surface intended to come into contact with the ground, said tread surface being composed, when said tire is in contact with the ground, of a contact area and a free area, • at least one air diversion device comprising an air inlet, a duct, and an air outlet, • at least one particle collector, • the air intake being positioned on the vehicle and configured to collect air having a velocity at the air intake level at least equal to 30% of the vehicle's speed, • the duct carrying the air to the air outlet, the air outlet of the air diversion device being axially anterior to the most axially posterior points of the free area of ​​the rolling surface and intended to direct an airflow over at least a portion of the free area of ​​the rolling surface of said tire, • the particle collector is intended to collect a portion of the airflow directed by the air outlet.

[0008] The invention consists of creating an airflow along the free part of the rolling surface, in the circumferential direction towards the rear part where the collector is located, from a part of the tire upstream of the collector.

[0009] In a conventional passenger vehicle where the tires are located in a dedicated space in the bodywork called a wheel well, the airflow around the free portion of the tread is very weak and sometimes runs in the opposite direction to the flow from the front of the vehicle to the rear due to its movement. Indeed, the speed of the tread in contact with the air in the wheel well, at the point opposite the center of the contact patch, is approximately equal to the speed of the vehicle, which is moving from rear to front. The rotation of the wheel and tire therefore tends to create an airflow around the free portion of the tread from the rear of the tire to the front of the tire. This flow due to the tire's rotation is disrupted by the airflow generated by the vehicle's movement, which, depending on the speed, can be negligible or dominant.Thus, without a specific device, the airflow along the free part of the tread surface is disordered and turbulent, and therefore unsuitable for carrying tire wear particles from the free part of the tread surface to the collector.

[0010] Furthermore, the wear particles exhibit their own motion when they are detached from the tread surface, a centrifugal motion relative to the tire but highly dependent on the particle's ejection position relative to the collector. If the particle is ejected between the point where it leaves the contact patch and an angle of 30° beyond this point, the probability that the particle will enter the collector is low but not zero, as the centrifugal force tends to propel the particle towards the collector. If the particle is detached from the tread surface on another portion of the free end, the centrifugal force and the turbulent flow around the free end make it unlikely that the resulting trajectory of said particle will lead it into the collector.

[0011] In our explanations, we assume that the vehicle is traveling in a straight line with no external wind on a flat, level surface. The airflow is therefore generated by the movement of the car. This approximation is common in the design of vehicles that undergo wind tunnel testing, the wind tunnel simulating an airflow generated by the vehicle's movement in a straight line.

[0012] The state of the art, and in particular JP 2008302803 A, proposes creating a flow towards the manifold by suction. This flow will naturally draw in not only the air from the wheel arch but also the airflows circulating along the bodywork, airflows which may be predominant compared to the flows coming from the wheel arch. This solution is not satisfactory with regard to the trajectory of the particles.

[0013] The invention consists of drawing a portion of the airflow circulating around the bodywork and directing it onto the free part of the running surface so as to create a laminar or vortex flow along this free part of the running surface towards the manifold. This flow is maintained laminar until it reaches the manifold by the presence of physical barriers, namely the running surface, the wheel arch, and the airflow circulating along the bodywork. Surprisingly, finite element calculations have shown that such a flow does not become turbulent before reaching the manifold, but rather circulates between the running surface, the wheel arch, and the external airflow, regardless of whether the inlet of the laminar flow in the wheel arch is positioned in front of the tire or at the outermost vertical points of the tire.This flow also has the advantage of being directed towards the collector by the outside airflow passing along the bodywork and then along the tire, and going towards the underside of the bodywork after the contact area, which greatly optimizes the collection of particles.

[0014] A tire is a torus equipped with a central axis that coincides with its axis of rotation. A tire is easily described in a cylindrical coordinate system whose transverse axis is its axis of rotation, and whose radial axis is the axis perpendicular to the axis of rotation. The forces exerted on the tire by its tread surface are decomposed into forces along the transverse axis, or drift forces, and torque forces along a direction tangent to the tread surface and perpendicular to the transverse axis.

[0015] A vehicle—car, van, truck, motorcycle, etc.—always has a principal steering direction when the sum of the tire slip forces is zero, that is, when the vehicle is moving in a straight line and in a direction generally determined by the most comfortable driving position for the driver or the maximum number of gears offered by the gearbox. This principal axis allows us to determine the front, or the most axially forward point of the vehicle, and the rear, or the most axially rear point of the vehicle. Assuming the ground is flat and level, the vehicle has a transverse direction (YY') and a vertical direction (ZZ') perpendicular to the axial direction. This reference point is attached to the vehicle and remains constant regardless of the road configuration.Thus, a point on the vehicle being rear, or axially anterior to another, means that the first point is closer to the rear of the vehicle than the second point. Similarly, one can... define points vertically lower or higher than other points and points transversely outside or inside other points.

[0016] The maximum width of the tires is measured in the direction of the axis of rotation, the tire being inflated to the nominal pressure recommended by the vehicle manufacturer, the vehicle being empty.

[0017] To draw a portion of the airflow circulating around the body, the wear particle collection device includes an air diversion device comprising an air inlet, a duct, and an air outlet. The air inlet can be located on any part of the vehicle—its front, sides, or underside—for example, by means of a protruding structure to channel air toward the air inlet of the air diversion device, or from an air intake vent located on a body structure subjected to outside air pressure when the vehicle is moving, such as the front structures of the vehicle. If the inlet is supplied by a protruding structure, this structure can be retractable, particularly depending on the vehicle's speed, so as to draw only the air necessary to create a laminar flow over the free portion of the tire's contact patch.Thus, the energy consumption involved in the rolling resistance of such a structure can be limited to the bare minimum.

[0018] Preferably, the air inlet of the bypass device is located in front of the air outlet of said device to reduce pressure losses. The air outlet is positioned close to the tire and directed towards the tire's tread. A structure of the air outlet may also protrude into the wheel well to best direct the laminar flow along the tread.

[0019] Advantageously, the air inlet is located under the vehicle and is configured to collect the air passing under the vehicle as it moves. This position is the most advantageous for collecting an efficient laminar flow to collect tire wear particles. The inventor compared two devices: one where the air inlet protrudes under the vehicle, which generates a stable and efficient laminar flow in the duct, and one where the air inlet is positioned on the front grille of the vehicle, which, due to the airflow over the bodywork, generates a turbulent flow in the duct, making it less efficient at creating an airflow over the tire tread towards the collector. Advantageously, the protruding element creates an inlet surface whose normal vector is coplanar with the axial direction.By substantially coplanar, we mean that the angle between the plane determined by the axial and vertical directions and the plane determined by the normal vector to the input surface and the vertical axis is less than 10°.

[0020] Preferably, the width of the air inlet, measured in the transverse direction of the vehicle, is at least equal to one-tenth of the maximum tire width, and preferably, at most equal to 1.25 times the maximum tire width, depending on whether it is desirable to create a Venturi effect or laminar flow with higher static pressure. Advantageously, the axial width of the air outlet is between the width of the tread and the maximum width of the wheel arch.

[0021] For similar reasons, a preferred solution is for the average cross-section of the duct to have an area between 0.1 and 2 times the area of ​​the air inlet. Advantageously, the average fiber of the duct is differentiable from the air inlet to the air outlet so as to preserve as much as possible the laminar nature of the flow reaching the outlet. Breaks in differentiability, such as sharp bends in a duct, tend, depending on their severity, to disrupt the laminar nature of the flow.

[0022] Advantageously the air outlet of the air bypass device is axially anterior to the most axially posterior points of the free area of ​​the rolling surface, indeed it is necessary that the airflow brought by the outlet be able to slide over at least a portion of the free part of the rolling surface.

[0023] The air outlet is configured to create a laminar airflow along the tread surface towards the wear particle collector. If the air outlet is oriented perpendicular to the tread surface, the airflow will split into two parts and potentially create a turbulent flow with an unpredictable direction. By directing the airflow captured by the air bypass device tangentially to the tire tread, the airflow remains laminar and significantly increases its efficiency in conveying the tire wear particles to the collector.

[0024] For this reason, preferably, the air outlet is configured to direct an airflow in a direction making an angle A, in a plane perpendicular to the transverse direction, with the tangent T to the tire at point J, at most equal to 45°, point J being the projection along the axial direction onto the contact surface, of the outer end of the air outlet, preferably the angle A being at most equal to 30°.

[0025] Advantageously, the outlet surface has a normal vector that is substantially coplanar with the axial direction. By substantially coplanar, it is meant that the angle between the plane determined by the axial and vertical directions and the plane determined by the normal vector to the outlet surface and the vertical axis is less than 10°.

[0026] Preferably, the air outlet has an area between 0.1 and 2 times the area of ​​the air inlet, depending on the desired effect at the air outlet and the type of wear particles generated by the tire. For fine and ultrafine particles For particles larger than 0.05 micrometers, we know that the speed of the laminar flow is essential for their collection. Their trajectories are dominated by the particle's lift, and therefore by the airflow. Generating a Venturi effect by reducing the cross-section between the air inlet and outlet can be beneficial. Conversely, for coarser particles, larger than 150 micrometers, their trajectories are dominated by their inertia. It may be advantageous to generate a higher static pressure in the laminar flow, thus increasing the cross-section between the air inlet and outlet of the air bypass device.

[0027] Advantageously, the inlet surface of the collector has a normal vector substantially coplanar with the axial direction. By substantially coplanar, it is meant that the angle between the plane determined by the axial and vertical directions and the plane determined by the normal vector to the outlet surface and the vertical axis is less than 10°.

[0028] To avoid pressure losses in the duct, the air inlet is positioned on the vehicle between planes perpendicular to the axis of rotation of the tire and passing through the outermost transverse points of said tire when the tires (3) of the vehicle (1) are configured so that the vehicle (1) moves in a straight line.

[0029] Advantageously, the wear particle collection device includes an air guide device configured to guide air between the air outlet of the wear particle collection device and the particle collector, preferably along the running surface. Such a device, which may include plates, is more effective than wheel arches and external airflow in maintaining the efficiency of directing the laminar airflow towards the collector.

[0030] Preferably, the air inlet is configured to collect air having a velocity at the air inlet that is at least 30% of the vehicle speed, preferably at least 50%, and preferably at least 80% of the vehicle speed. It is indeed important that the device be efficient in utilizing the speed of the vehicle on which the device is based.

[0031] Advantageously, a tire wear particle collection device is attached to the suspended part of the vehicle for reasons of ease of installation.

[0032] Advantageously, a tire wear particle collection device is attached to the unsprung part of the vehicle so as to have a system that maintains its effectiveness even on curved trajectories and allows for close monitoring of wheel movements

[0033] Preferably, the wear particle collection device is parameterized according to various vehicle parameters, preferably vehicle speed, tire slip angle, tire inflation pressure, tire load, ambient temperature, and acceleration. Vehicle, external humidity of the vehicle. Depending on these various parameters, it is beneficial for the system to activate or deactivate, or to adjust its settings to, for example, optimize airflow speed by increasing or decreasing the size of the air intake, or to prevent protruding body parts from contacting the ground or tire in the event of a puncture by retracting them, thus maintaining its effectiveness. For example, in rainy conditions, the system might not operate because particles are highly likely to be carried away by the rain.

[0034] An auxiliary means for generating airflow, such as a fan, can also be used in the modes covered by the invention, for example, for parking maneuvers that generate wear through friction even though the vehicle is stationary and therefore not generating any external airflow. On the other hand, an auxiliary suction means could compensate for pressure losses generated by a filtration system, for example.

[0035] The features and other advantages of the invention will be better understood with the aid of Figures 1 and 2, which respectively represent: - a side view of a vehicle equipped with devices for collecting wear particles from its front and rear tires, - a bottom view of a wear particle collection device according to the invention around a contact area of ​​one of the tires.

[0036] Figure 1 shows a vehicle (1) equipped with wear particle collection devices (2) for the front and rear tires (3). The vehicle (1) is a car having a main driving direction (XX') designated as the axial direction, a transverse direction (YY') and a vertical direction (ZZ') perpendicular to the axial direction. Each tire (3) comprises a tread (32) intended to come into contact with a ground (7), the tread (32) being composed, with said tire in contact with the ground, of a contact area (322) and a free area (321). Each wear particle collection device (2) includes an air bypass device (21) comprising an air inlet (211), a duct (212), an air outlet (213) and a particle collector (24), the air inlet (211) being here arranged under the vehicle to collect air (4).The duct (212) carries the air to the air outlet (213), which is axially anterior to the most axially posterior points of the free area (321) of the tread surface and is designed to direct an airflow (51) over at least a portion of the free area (321) of the tread surface (32) of the tire (3) under consideration. The particle collector (24) is positioned behind the tire and is designed to collect a portion of the airflow (51). The air outlet (213) is configured to direct an airflow in a direction (F) making an angle (A), in a plane perpendicular to the direction. transverse, with the tangent (T) to the tire at point J, here around 15°, point J being the projection along the axial direction onto the contact surface, of the outer end of the air outlet.

[0037] Figure 2 shows the wear particle collection device (2) for a tire viewed from below, the contact patch (322) being the black surface in the figure. The tire has a maximum width (31) measured in the direction of the tire's axis of rotation. The air inlet (211) is positioned on the vehicle between the planes (PI, P2) perpendicular to the tire's axis of rotation and passing through the outermost transverse points of said tire when the tires (3) of the vehicle (1) are configured so that the vehicle (1) travels in a straight line on a flat surface. The width (2111) of the air inlet (21), measured in the transverse direction of the vehicle (1), is here close to the maximum width (31) of the tire (3).

[0038] The invention was simulated on a computer by comparing airflows naturally circulating around the tire on a vehicle having an axially rear particle collector at the most axially rear points of the contact patch at the level of the vertically lower part of the vehicle in a manner similar to the schematic representation in [Fig. 1]. The vehicle has tires of size 225 / 45 R17.

[0039] In a vehicle which does not have the invention, when the vehicle moves, an airflow is created from the front part of the tire along the free part of the contact surface which meets another airflow in the opposite direction created mainly by the rotation of the wheel, the two flows being evacuated laterally at the top for the front wheel of the vehicle and downstream of the rear wheel which is in the drag of the front wheel, which reduces the airflow due to the forward movement of the vehicle.

[0040] For a vehicle incorporating the invention, an air intake the width of the tire is positioned at the level of the protruding rocker panel to draw an airflow the width of the tire over a height of 6 cm, in planes perpendicular to the tire's axis of rotation, passing through the points furthest transversely from the tire, the vehicle being configured to travel in a straight line on a level surface. The air is directed towards the axially forward part of the wheel arch with an air outlet located between said planes, orienting the air to make an angle of approximately 30° with the tangent to the tire at point J, point J being the projection along the axial direction onto the contact surface of the outer end of the air outlet. This orientation allows a continuous and laminar airflow to be created along the free surface of the tire up to the manifold.

[0041] A configuration with an air intake on the front of the vehicle, of the same dimensions between the same planes, all other things being equal, has shown an efficiency of Collection is significantly reduced. Indeed, the airflow over the front part of the vehicle, whose shape is designed to improve the vehicle's penetration into the air, creates a disturbance at the air intake and tends to create a turbulent flow that is much less efficient at bringing wear particles to the collector.

[0042] The air intake as tested creates a laminar flow of approximately 400 m³ / h at 50 km / h with an impact of less than 2% of the tire's rolling resistance, and approximately 900 m³ / h at 120 km / h with an impact of less than 13% of the tire's rolling resistance. For dust collection tests, a flow rate of 210 m³ / h is estimated to be sufficient. The ability to control the size of the air intake via a movable flap to obtain sufficient airflow for particle collection while reducing the solution's impact on vehicle fuel consumption is one of the advantageous solutions included in the invention.

[0043] This flow is particularly advantageous for bringing particles smaller than 100 mm to the collector, as their inertia is insufficient for them to travel along their natural trajectory without additional energy input. Furthermore, particles smaller than 100 mm travel up the free rolling surface and are not only present at the contact patch exit; the airflow created by the invention allows for the collection of most of them. Calculations have shown that the system improves particle collection by up to 50% on average compared to a simple collector behind the tire, specifically by 90% for particles emitted on the free portion of the rolling surface symmetrical to the contact patch with respect to the tire's axis of rotation, and more particularly for particles between 0.1 mm and 100 mm in size.

Claims

Demands

1. A vehicle (1) equipped with at least one device (2) for collecting wear particles from at least one tire (3), the vehicle (1) having a principal driving direction (XX') designated as the axial direction, a transverse direction (YY') and a vertical direction (ZZ') perpendicular to the axial direction, comprising: • each tire having a maximum width (31) measured in the direction of the tire's axis of rotation, comprising a tread (31) comprising a tread surface (32) intended to come into contact with a ground (7), said tread surface (32) being composed, when said tire is in contact with the ground, of a contact area (322) and a free area (321), • at least one air diversion device (21) comprising an air inlet (211), a duct (212), an air outlet (213), • at minus a particle collector (24),• characterized in that the air inlet (211) is disposed on the vehicle and configured to collect air (4) having a velocity at the air inlet (211) at least equal to 30% of the vehicle speed (1), • in that the duct (212) carries the air to the air outlet (213), the air outlet (213) of the air diverter device (21) being axially anterior to the most axially posterior points of the free area (321) of the running surface and intended to direct an airflow (51) onto at least a portion of the free area (321) of the running surface (32) of said tire (3), • and in that the particle collector (24) is intended to collect a portion of the airflow (51) directed by the air outlet (213).

2. Vehicle (1) according to claim 1 wherein the air inlet (211) is located under the vehicle (1) and is configured to collect the air passing under the vehicle when the vehicle is moving.

3. Vehicle according to claim 1 or 2 in which the width (2111) of the air inlet (21), measured in the transverse direction of the vehicle (1), is at least equal to one-tenth of the width maximum (31) of the tire (3), preferably, at most equal to 1.25 times the maximum width (31) of the tire (3).

4. Vehicle (1) according to any one of the preceding claims in which the average section of the duct (212) has an area between 0.1 and 2 times that of the air inlet (211).

5. Vehicle (1) according to any one of the preceding claims in which the air outlet (213) has an area between 0.1 and 2 times that of the air inlet (211).

6. Vehicle (1) according to any one of the preceding claims wherein the air inlet (211) is positioned on the vehicle between the planes (PI, P2) perpendicular to the axis of rotation of the tire and passing through the outermost transverse points of said tire when the tires (3) of the vehicle (1) are configured so that the vehicle (1) moves in a straight line.

7. Vehicle (1) according to any one of the preceding claims wherein the air outlet (213) is configured to direct an airflow in a direction (F) making an angle (A), in a plane perpendicular to the transverse direction, with the tangent (T) to the tire at point J, of at most 45°, point J being the projection along the axial direction onto the contact surface, of the outer end of the air outlet, preferably the angle (A) being at most 30°.

8. Vehicle (1) according to any one of the preceding claims wherein the wear particle collection device (2) comprises an air guidance device (52) configured to guide air between the air outlet (213) of the wear particle collection device and the particle collector (24).

9. Vehicle (1) according to claim 8 in which the air guidance device (52) guides the air along a portion of Faire free (321) of the tire.

10. Vehicle (1) according to any one of the preceding claims wherein the particle collector (24) is axially posterior to the rear end of the contact patch (322) of the tire (3) and is axially posterior to the air inlet (211).

11. Vehicle (1) according to any one of the preceding claims wherein the wear particle collection device (2) is parameterized according to various vehicle parameters (1) preferably vehicle speed, tire slip angle, tire inflation pressure, tire load,

12. the outside temperature of the vehicle, the vehicle's acceleration, the outside humidity of the vehicle. Vehicle (1) according to any one of the preceding claims wherein the air inlet (211) is configured to collect air (4) having a velocity at the level of the air inlet (211) at least equal to 50%, preferably 80% of the speed of the vehicle (1).

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