Patent Application
20190248191
The invention relates to a tire having a tread with asymmetric tread elements and at least one off-center noise damper for absorbing the resonance of air in the tire cavity.
A tire comprises a summit with a tread for contacting the ground through a rolling surface. In a known manner, the tread of a tire, whether intended to equip a passenger vehicle or a heavy goods vehicle, is provided with a sculpture including, in particular, tread elements or elementary blocks delimited by various grooves, including primary, longitudinal or circumferential, transverse or even oblique grooves, the elementary blocks also being able to include various finer incisions or lamelles. The grooves form channels intended to evacuate water during rolling on wet surfaces.
Such tires are also provided with a sealed inner liner that defines a cavity of the tire when the tire is mounted on a mounting rim. During rolling, the vibrations of the air in the cavity generate phenomena of resonance, hereafter called “cavity resonance”. These sound waves are transmitted to the interior of the vehicle. They are significant and unpleasant for the vehicle's passengers.
The introduction of a noise damper into the tire cavity (often attached to the inner liner) is known as an effective means of reducing the amplitude of these phenomena of resonance. For example, the integration of a foam strip in order to absorb cavity resonance is commercially available as a single band version (as shown in
A tire 100 of
A tire 200 of
On very high-end vehicles with speed ratings (Y), manufacturers demand very high levels of performance. The foam strips have the particularity of being also thermal insulators which have the consequence of increasing the temperature inside the summit, which can lead to a lower performance on high-speed tests.
It is thus sought how to dampen the cavity resonance efficiently while maintaining excellent performance at high speed.
The invention relates to a tire for a vehicle. The tire includes a summit having a tread with asymmetric tread elements for contacting the ground, and the tire is provided with a sealed inner liner that defines a tire cavity when the tire is mounted on a rim. A first noise damper is circumferentially secured to an inner surface that faces the tire cavity. The first noise damper is positioned in the tire cavity to an outer side of the tire and is off-center relative to a median plane of the tire.
According to one embodiment, the first noise damper is fixed axially externally relative to the median plane of the tire.
In some embodiments, the tire includes a second noise damper that is circumferentially secured to the inner surface that faces the tire cavity. The second noise damper is positioned in the tire cavity towards an inner side of the tire and is off-center relative to a median plane of the tire. Advantageously, the center of gravity of the set of noise dampers is located toward the outer side of the tire.
Each noise damper includes a foam strip that is circumferentially secured to the inner surface of the tire facing the tire cavity. Each foam strip has a continuous length, and each foam strip has a continuous width and a continuous thickness over the entire continuous length of the foam strip.
According to one embodiment, the tread includes several circumferential grooves, including primary grooves having respective widths, an inner groove closer to the inner side of the tire and an outer groove closer to the outer side of the tire. The width of the inner groove and the width of the outer groove are different from each other and are also different from the widths of the primary grooves such that the tread has sculpture elements that are asymmetric with respect to the median plane of the tire.
According to one embodiment, the first noise absorber is disposed axially directly facing radially opposite a primary groove as well as the outer groove. Advantageously, the second noise damper is disposed axially directly facing radially opposite the inner groove.
The invention also relates to a noise reduction system for tires, including a tire as described above.
The nature and various advantages of the presently disclosed invention will become more apparent upon consideration of the following detailed description, taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout, and in which:
Reference will now be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation and not limitation of the disclosed invention. Thus, it is intended that the invention covers these modifications and variants insofar as they fall within the scope of the appended claims and their equivalents.
For a tire having a geometry of revolution with respect to an axis of rotation, the geometry of the tire is generally described in a meridian plane containing the axis of rotation of the tire. For a given meridian plane, the radial, axial and circumferential directions respectively designate the directions perpendicular to the axis of rotation of the tire, parallel to the axis of rotation of the tire and perpendicular to the meridian plane.
As used herein, the term “pneumatic” includes, but is not limited to, tires used for light vehicles, passenger cars, utility vehicles (including heavy goods vehicles), recreational vehicles (including, without limitation, bicycles, motorcycles, ATVs, etc.), agricultural vehicles, military vehicles, industrial vehicles, mining vehicles and construction equipment.
Referring now to the figures, in which the same numbers identify identical elements,
In the invention, the noise dampers are formed from known materials including sponge materials. The sponge materials can include foams, including foamed plastics and foam resins of foam rubbers (e.g., chloroprene rubber, ethylene propylene (EPDM) rubber, nitrile butadiene and their equivalents). A sponge that includes open cell foam resins (e.g., polyethylene and polyurethane) is an effective means of attenuating cavity resonance, in order to limit the weight of the tire and preserve the durability of the noise dampers.
Referring to
The tire 300 has a first noise damper 330 for absorbing the cavity resonance of the tire. The noise damper 330 includes a foam strip having a continuous width L330 and a continuous thickness E330 along the entire length of the strip. The noise absorber 330 is circumferentially secured by known means to the inner surface 300a of the inner liner that faces the cavity of the tire 300.
The noise absorber 330 is off-center with respect to the median plane C300 of the tire 300 by a predetermined distance D330a. This distance is measured with respect to an edge 330a of the first noise damper 330 that is closer to the median plane C300. In some embodiments, the edge 330a coincides with a line X that passes through the point of intersection between a base and a wall of the groove 318′. With respect to the inner surface 300a, a predetermined distance D330b is measured with respect to an opposite edge 330b of the first damper 330 that is closer to the outer side of the tire. The edges 330a, 330b together define the continuous width L330 such that the first noise damper 330 is disposed axially directly facing radially opposite the primary groove 318′ as well as the outer groove 322. Thus, the first noise damper 330 is positioned towards the outer side of the tire.
Referring to
The second noise damper 332 is off-center with respect to the median plane C300 of the tire 300 by a predetermined distance D332a. This distance is measured with respect to an edge 332a of the second damper 332 that is closer to the median plane C300. An opposite edge 332b of the second noise damper 332 is positioned closer to the inner side of the tire. The edges 332a, 332b together define the continuous width L332 such that the second noise damper 332 is placed axially directly facing radially opposite the inner groove 320. In some embodiments, the second noise damper 332 is aligned along a line Y that passes through the center of gravity of the second noise damper and in the middle of the width L320. By placing the second noise damper 332 facing radially of the inner groove 320, the heat produced by high speeds can be released through the bottom of the groove 320.
The dampers are preferably arranged axially internally relative to the lateral ends of the reinforcements of the summit block of the tire. Preferably, this distance is greater than 25 mm. This configuration limits the increase in temperature to the edge of the summit block.
A test was carried out on tires of size 275/35ZR21 103Y, asymmetric, tested with a camber angle of −1.5° in order to take into account the technical requirements of a vehicle to which it is specifically dedicated. The tires are intended to be mounted on wheel rims of the size 9.5J21.
The tires correspond to the embodiments as described:
For tires using foam strips, the selected foam is an open-cell polyurethane foam. A commercial example of such a foam is Metzonor 023 from Metzeler Schaum GmbH. Its density is 23 kg/m3.
At an ambient temperature of 25° C., the test consists of rolling the tire on a metallic flywheel having a circumference of 8.5 m, at a pressure of 3.2 bar and a regulated load of 598 daN. The tire rolls in increments of increasing speeds, each lasting 20 minutes, and the increment in speed is 10 km/h. The tires are classified according to the maximum speed reached and the running time during the last stage reached. The results of the tests are given in Table 1.
This result demonstrates the increase in endurance performance at very high speed induced by the presence of offset foam associated with an asymmetric sculpture during tests under negative camber.
This result is attained in conserving a good performance while limiting cavity resonance.
With the tires as described, it is understood that a direction of mounting the tires on the vehicle is predetermined by the manufacturer. The tires have an outer axial edge and an inner axial edge, with the inner axial edge being the edge to be mounted next to the vehicle body when the tire is mounted on the vehicle in the predetermined mounting direction and inversely for the outer axial edge. The addition of foam strips in the described tires results in differences in the speed limit of these tires as a function of the direction of mounting on the vehicle. It is therefore advisable to give users the means to avoid mistakes in the direction of installation of the foam and the direction of mounting of the tire on the rim, and then to verify that the direction of mounting imposed on the rim has been respected. As used herein, “outer side of the vehicle” designates the outer axial edge.
Although the dampers are shown with a generally rectangular cross-section, other cross-sectional geometries may be employed. For example, geometries having a greater base width, such as trapezoids and triangles.
While one tire may benefit from a single foam strip as described, another tire may benefit from two, three or more foam strips that function as the noise dampers. Both embodiments of the tire are influenced by the overall tread pattern of the asymmetrical tread and at least one off-center noise damper in the tire cavity.
While particular embodiments of the disclosed invention have been illustrated and described, it is to be understood that various changes, additions and modifications may be made without departing from the spirit and scope of the present disclosure. Therefore, no limitation should be imposed on the scope of the invention as described with the exception of those set out in the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1658287 | Sep 2016 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2017/071796 | 8/30/2017 | WO | 00 |
