WO2020250178A1

WO2020250178A1 - Method and machine for the aerodynamic analysis of the emissions of microplastics generated by the rolling of a pneumatic tyre upon a road pavement

Info

Publication number: WO2020250178A1
Application number: PCT/IB2020/055498
Authority: WO
Inventors: Luca Lelio
Original assignee: Bridgestone Europe Nv/Sa
Priority date: 2019-06-13
Filing date: 2020-06-11
Publication date: 2020-12-17
Also published as: IT201900008886A1

Abstract

A method and a machine for the aerodynamic analysis of the emissions of microplastics generated by the rolling of a pneumatic tyre provided with a wind tunnel having a concentrator duct for directing a flow of air within a test chamber and a diffusor duct wherefrom the airflow from the test chamber is discharged; a test station (13) obtained inside the test chamber and intended to accommodate a pneumatic tyre and having a counter device (14) arranged below the pneumatic tyre, at least one portion whereof reproduces the characteristics of asphalt and whereupon the pneumatic tyre runs in order to simulate rolling upon a road pavement; and means that are suitable for detecting and/or collecting the microplastics generated by the rolling of the pneumatic tyre upon the counter device (14) during a test step.

Description

METHOD AND MACHINE FOR THE AERODYNAMIC ANALYSIS OF THE EMISSIONS OF MICROPLASTICS GENERATED BY THE ROLLING OF A

PNEUMATIC TYRE UPON A ROAD PAVEMENT

DESCRIPTION

TECHNICAL SECTOR

The present invention relates to a method and machine for the aerodynamic analysis of the emissions of microplastics generated by the rolling of a pneumatic tyre upon a road pavement .

PRIOR ART

As is known, the term microplastics refers to particles of a plastic material of reduced dimensions (generally smaller than one millimeter) that can be released directly into the environment, or that can be obtained from the degradation of plastic material objects of larger dimensions, or else by the abrasion of pneumatic tyres caused by the rolling upon a road pavement .

Environmental protection regulations are becoming increasingly stringent and the need is therefore increasingly felt to be able to implement an aerodynamic analysis of the emissions of microplastics generated by the rolling of a pneumatic tyre upon a road pavement.

These measures are however, of course not applicable to the existing tires, wheels and vehicles.

DESCRIPTION OF THE INVENTION

The aim of the present invention is thus to provide a machine for the aerodynamic analysis of the emissions of microplastics generated by the rolling of a pneumatic tyre upon a road pavement that is free from the disadvantages of the state of the art and that is, in particular, easy and inexpensive to implement.

A further aim of the present invention is to provide a method for the aerodynamic analysis of the emissions of microplastics generated by the rolling of a pneumatic tyre upon a road pavement that is free from the disadvantages of the state of the art and that is, in particular, easy and inexpensive to implement.

According to the present invention, a method and a machine are provided for the aerodynamic analysis of the emissions of microplastics generated by the rolling of a pneumatic tyre upon a road pavement according to that determined within the attached claims .

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described with reference to the accompanying drawing which illustrates an example of a non-limiting embodiment, wherein the attached figure is a schematic and perspective view of a machine for the aerodynamic analysis of the emissions of microplastics generated by the rolling of a pneumatic tyre upon a road pavement manufactured according to the present invention. PREFERRED EMBODIMENTS OF THE INVENTION

In Figure 1, the number 1 indicates, in its entirety, a machine for the aerodynamic analysis of the emissions of microplastics generated by the rolling of a pneumatic tyre 2 upon a road pavement .

The machine 1 comprises a wind tunnel 3 that is used to study the behavior of the pneumatic tyre 2 immersed within a fluid, which in this case is air. The wind tunnel 3 preferably has a closed cycle comprising a substantially annular conduit wherein the air is directly recirculated therewithin, without the air being exchanged with the external environment.

The wind tunnel 3 comprises a pneumatic tyre 2 test chamber 4.

The wind tunnel 3 comprises a concentrator 5, i.e., a conduit that narrows in order to accelerate the air, that is arranged before (upstream of) the test chamber 4.

The wind tunnel 3 further comprises a diffuser 6, i.e., a duct wherefrom the airflow from the test chamber 4 is discharged and that widens in order to slow the air after (downstream of) the test chamber 4.

Furthermore, the wind tunnel 3 comprises a fan 7 that is driven by a motor that allows for forced circulation of the air within the wind tunnel 3.

Preferably, the wind tunnel 3 also comprises flow deflectors 8 that are intended to reduce the rotational motion of the air due to the fan 7 and that are suitable for allowing a substantially laminar flow of air within the test chamber 4. The flow deflectors 8 are preferably mounted upstream of the concentrator 5.

The wind tunnel 3 then comprises a further three ducts 9 and four elbows in order to connect the diffuser 6 to the concentrator 5 and in order to achieve the correct circulation of the airflow.

Advantageously, the wind tunnel 3 comprises a smoke and/or fog generator 10 in order to visualize the aerodynamic lines of the airflow within the test chamber 4. Preferably, the smoke and/or fog generator 10 is interposed between the flow deflectors 8 and the concentrator 5.

Furthermore, downstream of the diffuser 6, a collector manifold 11 is arranged for the microplastics that are generated during the test step within the test chamber 4 and that are subsequently carried by the airflow. The collector manifold 11 is preferably implemented as a filter wherein, within the mesh thereof, the microplastics generated during the test step within the test chamber 4 are trapped. Preferably, the collector manifold 11 has the same dimensions as the outlet section of the diffuser 6.

Finally, insofar as the forced circulation of air within the wind tunnel 3 produces an increase in the temperature of the air itself, an air conditioning device 12 for the airflow is provided. The air conditioning device 12 is intended to condition (cool) the flow of air in such a way as to maintain its temperature within a range of predetermined values. Preferably, the air conditioning device 12 is achieved by means a heat exchanger wherewithin a conditioning fluid flows that exchanges heat with (receives heat from) the flow of air. Advantageously, the air conditioning device 12 for the airflow is arranged downstream of the diffuser 6; preferably, the air conditioning device 12 for the airflow is arranged downstream of the collector manifold 11 for the microplastics .

According to an alternative, not illustrated, the wind tunnel 3 is open and provides for an inlet (at the concentrator 5) and an outlet (at the diffuser 6) by means of which the air is exchanged with the surrounding environment.

Located within the test chamber 4 is a test station 13 for the pneumatic tyre 2 or else for a small-scale model (for example at a scale of 1:2 or 1:3) of a pneumatic tyre 2. In the discussion that follows, both a pneumatic tyre 2 of standard dimensions and a reduced-scale model will be indicated generically with pneumatic tyre 2.

Inside the wind tunnel 3, the pneumatic tyre 2 is brought into rotation around an axis of rotation X. The pneumatic tyre 2 is moved by a thermal motor or, alternatively, by an electric motor whereto the pneumatic tyre 2 is keyed. According to a preferred variant, the test station 13 comprises a transmission that transmits the movement to the pneumatic tyre 2 and that is coupled to the thermal/electric motor.

The test station 13 further comprises a counter device 14 arranged beneath the pneumatic tyre 2 and whereupon the pneumatic tyre 2 runs in order to simulate rolling upon a pavement road.

According to a first variant, the counter device 14 is implemented by means of a conveyor 15 arranged below the pneumatic tyre 2 and whereupon the pneumatic tyre 2 runs in order to simulate the rolling upon a road pavement. The conveyor 15 comprises a belt 16 (preferably driven by an electric motor) that runs on two rollers and that is implemented by means of the alternation of rigid sectors (substantially curving and non-deformable) that reproduce the characteristics of asphalt and flexible sectors in order to allow for the curvature at the rollers .

According to a second variant, not illustrated, the counter device 14 is implemented by means of a drum arranged below the pneumatic tyre 2 and whereupon the pneumatic tyre 2 runs in order to simulate rolling upon a road pavement. The drum is rotatable about an axis of rotation parallel to the axis X and comprises a rigid outer peripheral surface that reproduces the characteristics of asphalt. The drum can be driven by an electric motor or, alternatively, it can be mounted idle .

Advantageously, the test station 13 comprises an element 17 for cleaning the surface of the counter device 14 whereupon the pneumatic tyre 2 runs. In particular, the cleaning element 17 is implemented by means of a suction and/or scraper element, preferably located underneath the counter device 14 and opposite the pneumatic tyre 2.

Preferably, a vertical load is applied to the pneumatic tyre 2 in order to simulate normal usage operating conditions (in a known manner by means of an electric motor and/or a pneumatic device); accordingly, during the test step, the pneumatic tyre 2 is subjected to the effect of centrifugal loads and to the effect of ground loads.

The pneumatic tyre 2 comprises a toroidal carcass, which is constituted by a single carcass ply partially folded upon itself and therefore having laterally two layers overlapping one another. Two annular beads are provided at opposite sides of the carcass, each of which is surrounded by the carcass ply. The carcass supports an annular tread which is composed of a vulcanized rubber-based material and constitutes the crown of the pneumatic tyre 2; a tread belt is interposed between the carcass and the tread, which comprises two tread plies .

The tread is further provided with a tracer agent. The tracer agent is intended to render visible the trajectories of the microplastics emitted by the rolling of the pneumatic tyre 2 upon the counter device 14 during the test step.

According to a first variant, the tracer agent (for example a phosphorescent dye) has previously been added during the tread compound preparation step and is therefore contained within the polymeric matrix of the tread itself.

In this case, the method for the construction of the pneumatic tyre 2 provides, in the first place, for wrapping the carcass ply around a forming drum in order to confer an annular shape to the body ply in overlapping the two opposite ends of the carcass ply. Subsequently, the formation of the green pneumatic tyre 2 is completed in also bonding the other components to the carcass ply, such as the tread. Once the assembly of the green pneumatic tyre 1 has been completed, the latter is subjected to a vulcanization process within special molds in order to thereby obtain a pneumatic tyre 2 that is finished and ready for the test step.

According to a second variant, the tracer agent is implemented by means of electro-conductive metal powders (for example, copper, silver or gold) or graphite wherewith the polymers used in the manufacture of the tread are doped.

In this case, the method for the construction of the pneumatic tyre 2 provides, in the first place, for wrapping the carcass ply around a forming drum in order to confer an annular shape to the carcass ply in overlapping the two opposite ends of the carcass ply. The polymers used for the production of the tread are doped by means of the addition of metal powders or graphite, and subsequently, the formation of the tread is completed; the tread is then coupled to the carcass ply in such a way as to obtain a green pneumatic tyre. Once the assembly of the green pneumatic tyre 1 has been completed, the latter is subjected to a vulcanization process within special molds in order to thereby obtain a pneumatic tyre 2 that is finished and ready for the test step.

In this case, the test station 13 is provided with a device for the magnetic capture of the conductive microplastics (i.e., with added metal powders or graphite) that are generated during the test step within the test chamber 4. According to a first variant, the magnetic capture device is implemented by means of a magnetic plate (i.e., made of a magnetic material) arranged at a certain distance and in the proximity of the pneumatic tyre 2. According to a preferred variant, the magnetic plate has a profile that reproduces the profile of a fender of a car that surrounds, at least partially, the pneumatic tyre 2 in order to simulate the actual rolling conditions on the road pavement.

The test station 13 is also provided with a device 18 for measuring the speed of the airflow flowing within the test chamber 4; advantageously, the device 18 for measuring the speed of the airflow is implemented by means of a Pitot tube that is impacted by the flow of air flowing within the test chamber 4.

According to a first and preferred embodiment, the test station 13 further comprises at least one optical device 19, in particular a video camera, arranged in a position facing and in proximity to the pneumatic tyre 2 in such a way as to frame, in use, at least one analysis portion of the pneumatic tyre 2. The optical device 19 is intended to detect the trajectories of the microplastics (in particular, of the tracer agent) generated by the rolling of the pneumatic tyre 2 upon the counter device 14 during the test step. The optical device 19 is rigidly connected to a support member in such a way as to reduce any possible sources of vibration. It was experimentally verified that optical devices 19 comprising known types of CCD ( charge-coupled device) or CMOS (metal-oxide-semiconductor) sensors are characterized by reduced background noise and are able to provide satisfactory performance. The test station 13 comprises a data detection unit 20 connected to the optical device 19 and communicating with an external supervision unit 21, usually a computer. During the test step, the optical device 19 continuously detects images of the analysis portion and transmits them to the data detection unit 20. The external supervision unit 21 is intended to use the images of the analysis portion in order to obtain indications regarding the trajectories of the microplastics generated during said test step .

The method for the aerodynamic analysis of the emissions of microplastics therefore provides for constructing the pneumatic tyre 2 and implementing a test step of a predetermined duration wherein the pneumatic tyre 2 is brought into rotation around its axis X under certain conditions of applied speed and load; during the test step, the pneumatic tyre 2 runs upon the counter device 14 in order to simulate rolling upon a road pavement. The microplastics are then collected that are generated by the abrasion of the pneumatic tyre 2 during the test step and which are deposited upon the collector manifold 11 and/or upon the magnetic capture device in order to obtain an indication of the quantity and dimensions of the microplastics generated during said test step .

The pneumatic tyre 2 construction step may provide for a step wherein the tread is doped with a tracer agent that is intended to render visible the trajectories of the microplastics generated by the rolling of the pneumatic tyre 2 upon the counter device 14 during the test step. In particular, it is possible to envisage applying the tracer agent to the peripheral/outer surface of the tread of the finished pneumatic tyre and/or to construct the tread of the pneumatic tyre 2 in doping the polymers with electro- conductive metals powders (for example, copper, silver or gold) or graphite.

In the case where the optical device 19 is envisaged, the method involves continuously acquiring images of the analysis portion during the rotation of the pneumatic tyre 2. The external supervision unit 21 is intended to analyze said images in order to obtain indications regarding the trajectories of the microplastics generated during said test step .

The machine 1 for the aerodynamic analysis of the emissions of microplastics generated by the rolling of a pneumatic tyre 2 and the method described thus far have various advantages. In particular, they allow to simulate the normal functioning of the pneumatic tyre 2 such as to implement an effective and reliable aerodynamic analysis of the emissions of microplastics generated by the rolling thereof upon a road pavement .

LIST OF REFERENCE NUMBERS IN THE FIGURES

1 machine

2 pneumatic tyre

3 wind tunnel

4 test chamber

5 concentrator

6 diffuser

7 fan

8 flow deflectors

9 ducts

10 smoke generator

11 collector manifold

12 conditioning device

13 test station

14 counter device 15 conveyor

16 belt

17 cleaning element

18 speed measurement device

19 optical device

20 data detection unit

21 external supervision unit X axis of rotation

Claims

1.- A machine (1) for the aerodynamic analysis of the emissions of microplastics generated by the rolling of a pneumatic tyre (2) comprising:

a wind tunnel (3) having a concentrator duct (5) for directing a flow of air within a test chamber (4) and a diffuser duct (6) wherefrom the airflow from the test chamber (4) is discharged;

a test station (13) obtained within the test chamber (4) and intended to accommodate a pneumatic tyre (2) and having a counter device (14) arranged, in use, below the pneumatic tyre (2), one portion whereof reproduces the characteristics of asphalt and whereupon the pneumatic tyre (2) runs during a test step in order to simulate rolling upon a road pavement; and means (11, 19) that are suitable for detecting the trajectories of, and for collecting, the microplastics generated by the rolling of the pneumatic tyre (2) upon the counter device (14) during the test step.

2.- Machine according to claim 1, wherein said means (11, 19) comprise at least one optical device (19) arranged in a position facing and in proximity to the pneumatic tyre (2) in such a way as to frame at least one analysis portion of the pneumatic tyre (2) and to detect the direction of emission of the microplastics generated by the rolling of the pneumatic tyre (2) upon the counter device (14) during the test step.

3.- Machine according to claim 1 or 2, wherein said means (11, 19) comprise a device for the magnetic capture of the conductive microplastics generated by the rolling of the pneumatic tyre (2) upon the counter device (14) during the test step .

4.- Machine according to claim 3, wherein the magnetic capture device comprises at least one magnetic plate arranged at a certain distance and in the proximity of the pneumatic tyre ( 2 ) .

5.- Machine according to claim 4, wherein the magnetic plate has a profile that reproduces the profile of a fender of a car that surrounds, at least partially, the pneumatic tyre ( 2 ) .

6.- Machine according to any of the preceding claims, wherein said means (11, 19) comprise a collector manifold (11) for the microplastics generated by the rolling of the pneumatic tyre (2) upon the counter device (14) during the test step, preferably arranged downstream of the diffuser duct (6) ; wherein, said collector manifold (11) is preferably implemented as a filter that has the same dimensions as the outlet section of the diffuser duct (6) .

7.- Machine according to any of the preceding claims, wherein the counter device (14) is implemented by means of a conveyor (15); wherein the conveyor (15) comprises a belt (16) that runs on two rollers and that is implemented by means of the alternation of rigid sectors (substantially curving and non-deformable) that reproduce the characteristics of asphalt and flexible sectors in order to allow for the curvature of the belt (16) itself at the rollers.

8.- Machine according to any of the claims from 1 to 6, wherein the counter device (14) is implemented by means of a drum that is rotatable about an axis of rotation and that has a rigid outer peripheral surface that reproduces the characteristics of asphalt.

9.- Machine according to any of the preceding claims and comprising an element (17) for cleaning the surface of the counter device (14) whereupon the pneumatic tyre (2) runs; wherein, the cleaning element (17) is preferably implemented by means of a suction and/or scraper element located underneath the counter device (14) and opposite the pneumatic tyre ( 2 ) .

10.- Machine according to any of the preceding claims, wherein the test station (13) is also provided with a device (18) for measuring the speed of the airflow flowing within the test chamber (4); wherein, the device (18) for measuring the speed of the airflow is preferably implemented by means of a Pitot tube.

11.- Machine according to any of the preceding claims and comprising a conditioning device (12) implemented to maintain its airflow temperature within a predetermined range of values; wherein the conditioning device (12) is preferably arranged downstream of the diffuser duct (6) .

12.- Method for the aerodynamic analysis of the emissions of microplastics generated by the rolling of a pneumatic tyre (2) comprising the following steps:

accommodating a pneumatic tyre (2) within the test chamber (4) of a wind tunnel (3);

performing a test step wherein the pneumatic tyre (2) is brought into rotation around its axis (X) and wherein the pneumatic tyre (2) runs upon a counter device (14) in order to simulate rolling upon a road pavement; and

detecting the trajectories of, and collecting, the microplastics generated by the rolling of the pneumatic tyre (2) upon the counter device (14) during said test step.

13.- Method according to claim 12, wherein the test step is performed in applying a vertical load to the pneumatic tyre (2) .

14.- Method according to claim 12 or 13 and comprising the further step of providing the tread of the pneumatic tyre (2) with a tracer agent that is intended to render visible the trajectories of the microplastics generated by the rolling of the pneumatic tyre (2) upon the counter device (14) during the test step.

15.- Method according to claim 14 and comprising the further steps of :

constructing the tread of the pneumatic tyre (2) in doping the polymers with electro-conductive metal powders or graphite; coupling the tread to a carcass ply in such a way as to obtain a green pneumatic tyre (2) ; and

subjecting the green pneumatic tyre (2) to a vulcanization process in order to obtain a finished pneumatic tyre (2) .

16.- Method according to any of the claims from 12 to 15 and comprising the further steps of :

continuously acquiring images of the analysis portion during the rotation of the pneumatic tyre (2) ;

analyzing said images in order to obtain indications regarding the trajectories of the microplastics generated during said test step.