Individual sound absorbers for tire cavity noise reduction

Abstract

An array of individual sound absorbers (20a, 20b) is attached to the inner surface (122) of the annular tread (12) of a pneumatic tire (10) or the annular rim surface (34) of a wheel rim (30) to reduce tire cavity noise. Each sound absorber (20a, 20b) comprises a flexible sheet-like substrate (54), a sheet-like screen material (52), and a sound absorber (56) disposed within an enclosed space formed by the sheet-like substrate (54) and the sheet-like screen material (52).

Description

[Background technology]

[0001] The cavity sealed between the tire and the rim of the vehicle wheel has its own resonant frequency, like any other air cavity. When the frequency of road excitation matches the resonant frequency of the tire cavity, which is about 200 Hz, the tire cavity resonates, resulting in violent vibrations due to the coupling between the tire structure and the tire cavity. The vibrations amplify the spindle forces (i.e., the reaction forces applied to the rim center), which can be further transmitted into the passenger compartment via the suspension system. The resulting interior noise, called tire cavity resonance noise (or tire cavity noise for short), can be easily perceived by passengers. This noise is very unpleasant and significantly impairs the sound quality of the interior, since it is a low-frequency narrow-band noise. Summary of the Invention

[0002] It is desirable to reduce tire cavity noise. The present disclosure provides articles and methods for reducing tire cavity noise. In one aspect, the present invention describes a sound absorbing body including a flexible sheet-like substrate, a sheet-like screen material, and a sound absorbing material disposed in a closed space formed by the sheet-like substrate and the sheet-like screen material, the sound absorbing material extending along the longitudinal direction of the sound absorbing body.

[0003] In another aspect, the present disclosure describes a sound absorber assembly including a plurality of the above-mentioned sound absorbers, the sound absorbing material of adjacent sound absorbers being separated by gaps and the array of sound absorbers being discrete, and in some cases the plurality of sound absorbers being connected by connectors.

[0004] In another aspect, the present disclosure describes a pneumatic tire including an annular tread extending in a circumferential direction thereof and an array of individual sound absorbers, at least one of the sound absorbers being an absorber as described above or an absorber assembly as described above. Each of the individual sound absorbers is attached to an inner surface of the annular tread, and the array of individual sound absorbers is distributed along a circumferential direction of the tread.

[0005] In another aspect, the present disclosure describes a wheel rim including an annular rim surface extending in a circumferential direction thereof and an array of individual sound absorbers, at least one of the sound absorbers being an absorber as described above or an absorber assembly as described above, each of the individual sound absorbers being attached to the annular rim surface, the array of individual sound absorbers being distributed along the circumferential direction of the annular rim surface.

[0006] In another aspect, the present disclosure describes a wheel including a pneumatic tire including an annular tread extending circumferentially therearound, and an array of individual sound absorbers, at least one of the sound absorbers being an absorber as described above or an absorber assembly as described above, each of the individual sound absorbers being attached to an inner surface of the annular tread, and the array of individual sound absorbers being distributed circumferentially around the tread.

[0007] In another aspect, the disclosure describes a wheel including a wheel rim including an annular rim surface extending in a circumferential direction thereof and an array of individual sound absorbers, at least one of the sound absorbers being an absorber as described above or an absorber assembly as described above, each of the individual sound absorbers being attached to the annular rim surface, the array of individual sound absorbers being distributed along a circumferential direction of the annular rim surface.

[0008] In another aspect, the present disclosure describes a method for reducing tire cavity noise, the method comprising attaching an array of individual sound absorbers to at least one of (i) an inner surface of an annular tread portion of a pneumatic tire and (ii) an annular rim surface of a wheel rim. The pneumatic tire is mounted to the wheel rim to form an enclosed tire cavity. At least one of the sound absorbers is a sound absorber as described above, or a sound absorber assembly as described above.

[0009] Various unexpected results and advantages are obtained in the exemplary embodiments of the present disclosure. One such advantage of the exemplary embodiments of the present disclosure is that the articles and methods described herein for reducing tire cavity noise provide better acoustic performance in terms of higher energy dissipation and less additional weight effect in tire cavity resonances compared to typical solutions in which a layer of porous sound absorbing foam is attached on the inner surface of the tire tread.

[0010] The above is a summary of various aspects and advantages of exemplary embodiments of the present disclosure. The above "Summary" is not intended to describe each illustrated embodiment or every implementation of certain exemplary embodiments of the present disclosure. The following figures and "Description of the Preferred Embodiments" more particularly exemplify certain preferred embodiments that employ the principles disclosed herein. [Brief description of the drawings]

[0011] The present disclosure may be more fully understood from the following detailed description of various embodiments of the present disclosure when considered in conjunction with the accompanying drawings, in which:

[0012] [Figure 1 dash] FIG. 1' is an exploded partial view of a tire that includes a typical sound absorber or noise damper. [Figure 1A] 1 is a schematic cross-sectional view of a tire including an array of individual sound absorbers according to one embodiment. [Figure 1B] FIG. 1B is a perspective side view of the tire of FIG. 1A. [Figure 2A]FIG. 2 is a perspective side view of an array of individual sound absorbers according to one embodiment. [Figure 2B] FIG. 2 is a perspective side view of an array of individual sound absorbers according to another embodiment. [Diagram 3] FIG. 1 is a perspective side view of a wheel rim including an array of individual sound absorbers according to one embodiment. [Figure 4A] FIG. 2 is a perspective side view of an array of individual sound absorbers according to one embodiment. [Figure 4B] FIG. 2 is a perspective side view of an array of individual sound absorbers according to another embodiment. [Diagram 5] 1 is a schematic cross-sectional view of a sound absorber assembly according to one embodiment. [Figure 6A] FIG. 2 is a perspective side view of a sound absorber assembly according to one embodiment. [Figure 6B] FIG. 2 is a perspective side view of a sound absorber assembly according to another embodiment. [Figure 7A] FIG. 2 is a perspective bottom view of a sound absorber assembly according to one embodiment. [Figure 7B] FIG. 2 is a perspective bottom view of a sound absorber assembly according to another embodiment. [Figure 8] FIG. 1 is a schematic front view of the acoustic test setup.

[0013] In the drawings, like reference numbers refer to like elements. The above-identified drawings may not be drawn to scale and illustrate various embodiments of the present disclosure, however, other embodiments are also contemplated, as noted in the Detailed Description. In all cases, the disclosure describes the disclosure disclosed herein by way of representing exemplary embodiments, and not by way of express limitation. It should be understood that numerous other modifications and embodiments may be devised by those skilled in the art that are within the scope and spirit of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] One typical solution for reducing tire cavity noise in wheels is to bond a layer of porous, sound-absorbing foam onto the inner surface of the tire's tread. The foam layer extends continuously around the tire's circumference. FIG. 1' is an exploded partial view of a tire 10' including a continuous foam layer 20' attached to the inner surface of the tire's tread 12'. The continuous foam layer 20' extends around the tire's circumference to form a substantially closed loop. This solution is widely adopted by commercial tires and wheels for vehicles. For example, a continuous polyurethane (PU) foam layer is attached onto the inner tread of vehicle tires to reduce tire cavity noise.

[0015] The present disclosure has found that the conventional solution as shown in FIG. 1' may have some technical shortcomings. First, the acoustic performance of polyurethane (PU) foam is relatively low compared to other fibrous sound absorbing materials. The normal incidence sound absorption coefficient of a 25 mm thick PU foam sample in the desired frequency range of 100 Hz to 300 Hz is less than 0.1. Thus, although polyurethane (PU) foam has been widely used due to its low material cost, it may not be a desirable material for tire cavity noise reduction. In addition, the labor cost for gluing the continuous PU foam layer onto the tire is another concern of tire manufacturers. To achieve a better adhesion state, a pre-treatment is usually performed before the adhesion process to grind off the mold release layer (having a thickness of less than 0.5 mm) on the inner surface of the tread. Thus, the larger the area of ​​the continuous foam layer to be adhered to the tire, the higher the additional labor cost. For example, for a typical automobile tire, the pre-treated area is about 0.3 to 0.6 m 2The adhesive area is also proportional to the material cost of the adhesive. Furthermore, when a tire with a PU foam layer is punctured, the part of the PU foam covering the punctured area needs to be removed before the repair work. It can be difficult and expensive to remove the entire PU foam layer and replace it with a new one. In practice, the PU foam layer installed in a tire usually has a thickness of 25 mm and a width in the range of 150 mm to 180 mm. A typical tire circumference can be, for example, 2.372 m. Correspondingly, if the density of the PU foam is 50 kg / m 3 , assuming the width is 150 mm, the volume of the PU foam layer is 8.9 × 10 -3 m 3 This adds up to a weight of 445g. This extra weight can potentially reduce the fuel efficiency of the tyre.

[0016] Some embodiments of the articles and methods described herein are provided to reduce tire cavity noise while addressing the above problems with conventional solutions. The approaches described herein provide better acoustic performance in terms of higher energy dissipation and less added weight effect in tire cavity resonance compared to typical solutions in which a layer of porous sound absorbing foam is attached on the inner surface of the tire tread. FIG. 1A is a schematic cross-sectional view of a pneumatic tire 10 having an array of individual sound absorbers 20a according to one embodiment. FIG. 1B is a perspective side view of the tire 10 of FIG. 1A. The pneumatic tire 10 forms a substantially annular shape and includes a tread portion 12, a pair of sidewall portions 14, and a pair of axially spaced apart bead portions 16. The sidewall portions 14 extend radially inward from an end of the tread portion 12, and the bead portions 16 are located at the inner ends of the sidewall portions 14. The tread portion 12 has an outer surface 121 and an inner surface 122 opposite the outer surface 121. When the pneumatic tire 10 is mounted on a wheel rim, such as the wheel rim 30 of Figure 3 described further below, the open tire cavity is closed to form an annular closed tire cavity. In some embodiments, the inner surface of the tire 10 facing the cavity may be covered with an inner liner rubber having low air permeability.

[0017] The pneumatic tire 10 may be, for example, a tubeless radial tire for passenger cars. The pneumatic tire 10 may be made for use in passenger cars where a quiet interior is highly desirable, or may be a tire for a variety of applications, such as trucks, motorcycles, airplanes, bicycles, trailers, etc. The pneumatic tire 10 may also be a bias tire.

[0018] In the embodiment shown in FIG. 1A, an array of individual sound absorbers 20a is attached to the inner surface 122 of the tread portion 12. The sound absorbers 20a are distributed along the circumferential direction of the pneumatic tire 10. When sound waves propagate through one sound absorber to the next, the sound energy dissipates. Each sound absorber 20a is attached to the inner surface 122 of the tread portion 12, for example, via an adhesive or adhesive tape. The adhesive or adhesive tape can withstand high temperatures, for example, 80 degrees Celsius or higher. An exemplary adhesive tape includes, for example, one available under the trade name 9988 EG from 3M Company (St. Paul, MN). In many applications, the bond between the sound absorber 20a and the inner surface 122 of the pneumatic tire can withstand 800,000 or more cycles of repeated loading under the standard GB / T 4502-2016 (ISO 10191), which specifies a durability test with a minimum rotation speed of 80 km / h and a duration of 34 hours.

[0019] The sound absorbers 20a are individually distributed along the circumferential direction of the pneumatic tire 10. The sound absorbers 20a are considered to be individual because the sound absorbing materials of adjacent sound absorbers are separated by gaps. The length dimension of the sound absorbers 20a along the circumferential direction of the tire 10 may be in the range of, for example, about 3 mm to about 2.5 m, about 10 mm to about 1 m, or about 15 mm to about 0.5 m. The length dimension of the sound absorbers 20a along the circumferential direction of the tire 10 may be in the range of, for example, about 0.1% to about 100%, about 5% to about 99%, about 10% to about 99%, or about 20% to about 95% of the circumferential length of the inner surface 122 of the tire 10.

[0020] In some embodiments, adjacent absorbers may be connected by a connection such as, for example, the connection 21 in FIGS. 2A-2B (or 70c in FIGS. 6A and 6B) described further below. In some embodiments, adjacent absorbers may not be connected. For example, in the embodiment shown in FIGS. 2A-2B, there is a gap 22 between adjacent absorbers 20a along the circumferential direction of the tire 10. The connection 21 or gap 22 may have a length dimension along the circumferential direction ranging from about 1% to about 100% of the length of the absorber, for example. The absorbers 20a may be evenly distributed in the circumferential direction of the tire 10. It should be understood that adjacent absorbers may be connected by a connection, but the absorbent material of adjacent absorbers may be separated by a gap, and the absorbers may be considered to be separate.

[0021] The sound absorber 20a may have a width along a direction substantially perpendicular to the circumferential direction of the tire 10, for example, in the range of about 5 mm to about 250 mm. The width of the sound absorber may be, for example, in the range of about 1% to about 150% of the tread width of the tread portion 12. The tread width of the tread portion 12 of the pneumatic tire 10 is not particularly limited, but may be a width of 60 mm to 315 mm. The term "tread width" means the width of the portion of the pneumatic tire 10 that comes into contact with the road surface in a cross-sectional view including the center axis of the pneumatic tire 10. The tread width is not limited to the width of the tread portion 12 actually measured, and may be a width dimension given by a standard designation.

[0022] FIG. 2A shows an absorber assembly 210 according to one embodiment. The absorber assembly 210 includes an array of absorbers 20a attached to the inner surface 122 of the tread portion 12 of FIG. 1A. Adjacent absorbers 20a are connected by respective connectors 21 to form a continuous tape, band, or strip. Although adjacent absorbers 20a are connected by connectors 21, it should be understood that the connectors 21 are substantially free of absorbent material and that the absorbent material of adjacent absorbers may be separate. When the absorber assembly 210 is attached to the inner surface of the tire tread portion, a gap 22 is formed between the head and tail of the absorber assembly 210. In some cases, when the absorber assembly 210 is attached to the inner surface of the tire tread portion, the connectors 21 can connect the head and tail of the absorber assembly 210 to form a closed loop.

[0023] FIG. 2B shows an array of sound absorbers 20a arranged as a plurality of individual sound absorber assemblies that can be attached to the inner surface 122 of the tread portion 12 of FIG. 1A. Adjacent sound absorbers 20a are connected by respective connections 21 to form sound absorber assemblies 210a, 210b, 210c or 210d that are separated by gaps 22 when attached to the inner surface of the tire tread portion. It should be understood that this layout is beneficial for replacing damaged sound absorbers with new ones without replacing the entire array of individual sound absorbers. It should be understood that the sound absorber assembly can be formed by connecting any number of adjacent sound absorbers. It should also be understood that the array of sound absorbers can include any number of sound absorber assemblies.

[0024] 3 is a perspective side view of a wheel rim 30 including an array of individual sound absorbers 20b, according to one embodiment. The wheel rim 30 includes a pair of bead seats 32 upon which tire bead portions, such as bead portion 16 of FIG. 1A, sit. The wheel rim 30 has a rim surface 34. When a pneumatic tire is mounted on the wheel rim 30, the open tire cavity is closed to form an annular closed tire cavity, with the rim surface 34 of the wheel rim 30 facing the annular closed tire cavity.

[0025] In the embodiment shown in FIG. 3, an array of individual sound absorbers 20b is attached to the rim surface 34. The sound absorbers 20b are distributed around the wheel rim 30 in a circumferential direction. Each sound absorber is attached to the rim surface 34, for example, via an adhesive or adhesive tape. The adhesive or adhesive tape can withstand high temperatures, for example, 80 degrees Celsius or higher. An exemplary adhesive tape includes, for example, one available from 3M Company (St. Paul, MN) under the trade name 9988 EG. In many applications, the bond between the sound absorber 20a and the rim surface 34 of the wheel rim 30 can withstand 800,000 or more cycles of repeated loading under the standard GB / T 4502-2016 (ISO 10191), which specifies a durability test with a minimum rotational speed of 80 km / h and a duration of 34 hours.

[0026] The sound absorbers 20b are distributed individually along the circumferential direction of the wheel rim 30. The sound absorbers 20b are considered to be individual because the sound absorbing material of adjacent sound absorbers is separated by a gap. When a sound wave passes from one sound absorber to another, the energy of the sound wave dissipates. The length dimension of the sound absorber 20b along the circumferential direction of the wheel rim 30 may be in the range of, for example, about 3 mm to about 2.5 m, about 10 mm to about 1 m, or about 15 mm to about 0.5 m. The length dimension of the sound absorber 20b along the circumferential direction of the wheel rim 30 may be in the range of, for example, about 0.15% to about 100%, about 5% to about 99%, about 10% to about 99%, or about 20% to about 95% of the circumferential length of the rim surface 34.

[0027] Adjacent absorbers 20b may be connected by a connecting portion 21 or separated by a gap 22. The connecting portion 21 or gap 22 may have a length dimension along the circumferential direction, for example, in a range of about 1% to about 100% of the length of the absorber. In some embodiments, adjacent absorbers may be connected by a connecting portion, such as, for example, connecting portion 70c of FIG. 4, which is further described below. The absorbers 20b may be evenly distributed in the circumferential direction of the wheel rim 30. It should be understood that while adjacent absorbers may be connected by a connecting portion, the absorbing material of adjacent absorbers may be separated by a gap, and the absorbers may be considered to be individual.

[0028] The sound absorber 20b may have a width along a direction substantially perpendicular to the circumferential direction of the wheel rim 30, for example, in the range of about 5 mm to about 200 mm. The width of the sound absorber may be, for example, in the range of about 1.5% to about 100% of the rim width of the wheel rim 30. The width of the wheel rim 30 is not particularly limited, but may be 127 mm to 317.5 mm. The term "rim width" refers to the axial distance between a pair of bead seats 32.

[0029] FIG. 4A shows a sound absorber assembly 410 according to one embodiment. The sound absorber assembly 410 includes an array of sound absorbers 20b attached to the rim surface 34 of the rim 30 of FIG. 3. Adjacent sound absorbers 20b are connected by respective connectors 21 to form a continuous tape. When the sound absorber assembly 410 is attached to the rim surface 34, a gap 22 is formed between the head and tail of the sound absorber assembly 410. In some cases, when the sound absorber assembly 410 is attached to the rim surface 34 of the rim 30, the connectors 21 can connect the head and tail of the sound absorber assembly 410 to form a closed band. It should be understood that this closed loop configuration is beneficial to resist centrifugal forces when the wheel is rotating. In some cases, the connectors 21 in the closed band configuration may be made of a heat shrinkable film. When the heat shrinkable film is heated, for example in an oven or with a heat gun, the closed band configuration can shrink its circumferential length, thereby firmly bonding the individual sound absorbers 20b to the rim 30.

[0030] FIG. 4B shows an array of sound absorbers 20b arranged as a plurality of individual sound absorber assemblies that can be attached to the rim surface 34 of the rim 30 of FIG. 3. Adjacent sound absorbers 20b are connected by respective connections 21 to form sound absorber assemblies 410a, 410b, 410c, or 410d, which are separated by gaps 22 when attached to the rim. It should be appreciated that this layout is beneficial for replacing damaged sound absorbers with new ones without replacing the entire array of individual sound absorbers. It should be appreciated that the sound absorber assembly can be formed by connecting any number of adjacent sound absorbers. It should also be appreciated that the array of sound absorbers can include any number of sound absorber assemblies.

[0031] FIG. 5 is a schematic cross-sectional view of a sound absorber assembly 510 according to one embodiment. The sound absorber assembly 510 includes a plurality of sound absorbers 20a (see, for example, FIG. 1A) or sound absorbers 20b (see, for example, FIG. 3). Each sound absorber 20a or 20b includes a sheet-like screen material 52 and a sheet-like substrate 54, which are connected at their respective peripheries to form a closed space. A sound absorbing material 56 is disposed in the closed space formed by the substrate 54 and the screen material 52. An adhesive element 58 is provided for mounting the sound absorber assembly 510 on a surface. Adjacent sound absorbers 20a or 20b can be connected by a connecting portion 21, which can include at least one of the sheet-like screen material 52, the sheet-like substrate 54, or the adhesive element 58 extending into the gap area between the adjacent sound absorbers 20a or 20b. It should be understood that the connecting portion 21 can include other suitable materials for connecting adjacent sound absorbers 20a or 20b. The connecting portion 21 is substantially free of sound absorbing material 56, and adjacent sound absorbing materials 56 may be separate.

[0032] When the sound absorber assembly 510 is in use, the screen material 52 faces the air cavity when the absorber is attached to the rim surface (e.g., the rim surface 34 of the rim 30 in FIG. 3) or the tire tread (e.g., the inner surface 122 of the tread 12 in FIG. 1A). The screen material 52 may include one or more sheet-like materials, such as, for example, a thermoplastic polyurethane (TPU) film. From a mechanical standpoint, it should be understood that the screen material can protect the sound absorber when it undergoes large deformations when the tire deforms or the rim rotates. From an acoustic standpoint, it should be understood that the screen material can change the low frequency absorption of the sound absorber 56. The acoustic performance of the screen material is determined by its acoustic impedance Z, which is a complex function of its areal density and flow resistance. The analytical formula describing this relationship is:

number

[0033] In some embodiments, air impermeable screen materials (e.g., TPU films) can be used. The term "air impermeable" refers to the infinitely large flow resistance R in the above formula. f , indicating that the impermeable screen material introduces a pure reactive impedance. It should be appreciated that the pure reactive impedance of the air impermeable screen material is beneficial in increasing the low frequency absorption of the sound absorber.

[0034] In some embodiments, a porous screen material (e.g., an acoustic mesh fabric) may be used. Porous materials have a relatively low value of flow resistance R compared to air impermeable materials. f The porous screen material has an almost purely resistive impedance, i.e., Z≈R f Therefore, the presence of a porous screen material may not increase the low frequency absorption of the absorber, but it may increase the surface impedance of the absorber by R f The term "surface impedance" is defined as the acoustic impedance measured at the surface of the absorber.

[0035] The substrate 54 may include one or more flexible materials, such as, for example, polyurethane (PU) films. It should be understood that the substrate may include any suitable flexible material that has the desired deformation capability when attached to a curved surface (e.g., the rim surface or the inner surface of the tire tread). The substrate 54 is stretchable or conformable such that when it is subjected to strain or stretch from the surface to which it is attached, the substrate 54 can deform correspondingly without affecting the mechanical integrity of the sound absorber. In some embodiments, the maximum elongation to failure of the substrate may be, for example, 105% or more, 110% or more, or 115% or more. When the sound absorber is placed on the inner surface of the wheel tire, the substrate may be subjected to cyclic strain transmitted from the tread, which may generate heat due to repeated contact and release of the tread of the wheel tire. The substrate may itself be water- and oil-resistant, or may have a water- and oil-resistant coating on the substrate.

[0036] A sound absorbing material 56 is disposed in the closed space formed by the substrate 54 and the screen material 52. In some embodiments, the sound absorbing material is made from non-woven fibers. It should be understood that the sound absorbing material may include any suitable flexible material that has sound attenuation when sound waves pass through the porous microstructure of the sound absorbing material. The flow resistance of the sound absorbing material is one important material parameter for determining its sound attenuation performance. In some embodiments, the flow resistance of the sound absorbing material may be in the range of, for example, about 1000 mks rayl / m to about 50000 mks rayl / m, about 2000 mks rayl / m to about 20000 mks rayl / m, about 3000 mks rayl / m to about 10000 mks rayl / m, or about 4000 mks rayl / m to about 6000 mks rayl / m. The term "flow resistance" is defined as the ratio of flow resistance to thickness. The maximum temperature that the sound absorbing material can withstand may range, for example, from about 80 degrees Celsius to about 180 degrees Celsius.

[0037] In some embodiments, the sound absorbing material 56 and the impermeable screen material 52 may not be tightly or bonded together such that an air gap exists due to a loose connection between the two materials, which can further increase the low frequency absorption of the sound absorber.

[0038] The thickness of the sound absorbing material 56 may be, for example, in the range of about 0.5 mm to about 200 mm, about 1 mm to about 100 mm, or about 5 mm to about 50 mm. The length dimension of the sound absorbing material 56 along the longitudinal direction of the base material may be, for example, in the range of about 3 mm to about 2 m. The width dimension of the sound absorbing material perpendicular to the longitudinal direction of the base material may be, for example, in the range of about 5 mm to about 250 mm.

[0039] In some embodiments, vents can be provided on the screen material (e.g., screen material 52 in FIG. 5) to balance air pressure between the inside and outside of the absorber. In the embodiment shown in FIGS. 6A and 6B, the absorber assemblies 710 and 720 each include two absorbers or patches 70a and 70b connected side-by-side via a connection 70c or 70c'. Each of the absorber patches 70a and 70b may have a similar configuration to the absorber 20a or 20b shown in FIG. 5. As shown in FIG. 6A, the connection 70c connects two adjacent absorber patches and may include the sheet-like screen material 52 and the sheet-like substrate 54 of the absorber 510. In another embodiment, as shown in FIG. 6B, at least a portion of the connection 70c' may include the sheet-like substrate 54 but not the screen material 52. From a mechanical point of view, the connection 70c or 70c' allows the absorber assembly 710 or 720 to be easily bent and accommodate various rim surfaces 34 and various inner surfaces 122 of the tread portion 12. From an acoustic point of view, the connection 70c or 70c' can introduce an acoustic impedance change between two adjacent absorbers to provide more energy dissipation when sound waves propagate from one absorber to the other. The connection 70c is also advantageous for repairability. When one absorber of the absorber assembly is damaged and needs to be replaced with a new one, it is easy to cut off the absorber to be replaced at the connection. The vents 70d / 70e are arranged in the screen material 52 to balance the air pressure between the inside and outside of the absorber. It should be understood that the vents 70d / 70e can be made of a porous material to achieve a similar function.

[0040] Referring again to FIG. 5, adhesive elements 58 are provided for mounting the absorber assembly 510 on a surface. FIGS. 7A and 7B show various configurations and arrangements of adhesive layer(s) or tape(s). In FIG. 7A, a continuous layer of adhesive or adhesive element 58a is attached to a base sheet-like material under adjacent absorbers 20a / 20b. The adhesive or adhesive element 58a extends continuously across the connection 21. The continuous layout of the adhesive or adhesive tape is beneficial for ease of manufacture. In FIG. 7B, a discontinuous adhesive or adhesive tape 58b is attached to a substrate under each absorber 20a / 20b. The adhesive layer or adhesive tape 58b is not connected at the connection 21. It should be understood that the discontinuous layout of the adhesive or adhesive tape is beneficial for repairability in case one absorber needs to be replaced.

[0041] Unless otherwise indicated, all numbers expressing quantities or ingredients, property measurements, and the like used in the specification and embodiments are to be understood in all instances as being modified by the term "about". Thus, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and accompanying list of embodiments may vary depending upon the desired properties one of ordinary skill in the art would obtain utilizing the teachings of the present disclosure. At the very least, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques, which is not intended to limit the application of the doctrine of equivalents to the scope of the embodiments described in the claims.

[0042] Various modifications and variations can be made to the exemplary embodiments of the present disclosure without departing from the spirit and scope of the present disclosure. Therefore, it should be understood that the embodiments of the present disclosure are not limited to the exemplary embodiments described below, but are governed by the limitations set forth in the claims and any equivalents thereof.

[0043] List of Exemplary Embodiments Exemplary embodiments are listed below. It should be understood that any one of embodiments 1-14, 15-17, 18-23, 24-29, 30, 31, and 32-34 can be combined.

[0044] The first embodiment is a sound absorbing body, A flexible sheet-like substrate; A sheet-like screen material; A sound-absorbing material disposed in a closed space formed by the sheet-like base material and the sheet-like screen material, the sound-absorbing material extending along the longitudinal direction of the sound absorber; The sound absorbing body is provided with:

[0045] Embodiment 2 is the sound absorber of embodiment 1, wherein the flexible sheet-like substrate has a longitudinal stretchability of about 105% or more, about 110% or more, or optionally about 115% or more.

[0046] A third embodiment is the sound absorber according to the first or second embodiment, wherein the flexible sheet-like substrate comprises a water- and oil-resistant material.

[0047] Embodiment 4 is a sound absorber according to any one of embodiments 1 to 3, wherein the flexible sheet-like substrate comprises at least one of a rubber film, a polyurethane (PU) film, a thermoplastic polyurethane (TPU) film, a polypropylene (PP) film, a cast polypropylene (CPP) film, a polyethylene terephthalate (PET), a cast polyethylene terephthalate (CPET) film, or a TPU / PU coated fabric.

[0048] A fifth embodiment is the sound absorber according to any one of the first to fourth embodiments, wherein the sheet-like screen material has a flow resistance of 0.01 mks rayl or more, 1 mks rayl or more, or 1000 mks rayl or more.

[0049] In the sixth embodiment, the sheet-like screen material has a thickness of about 0.5 g / m 2 ~10000g / m 2 , or about 1 g / m 2~1000g / m 2 The sound absorber according to any one of the first to fifth embodiments has an areal density of

[0050] Embodiment 7 is a sound absorber according to any one of embodiments 1 to 6, wherein the sheet-like screen material comprises at least one of a mesh fabric, a nonwoven fabric, a woven fabric, a rubber film, a polyurethane (PU) film, a thermoplastic polyurethane (TPU) film, a polypropylene (PP) film, a cast polypropylene (CPP) film, a polyethylene terephthalate (PET) film, a cast polyethylene terephthalate (CPET) film, or a TPU / PU coated fabric.

[0051] An eighth embodiment is the sound absorber according to any one of the first to seventh embodiments, wherein one or more ventilation holes are formed on the sheet-like screen material.

[0052] Embodiment 9 is a sound absorber according to any one of embodiments 1 to 8, wherein the sound absorbing material comprises at least one of polyurethane (PU) foam, glass fiber material, mineral fiber material, polyester fiber material, polypropylene fiber material, nonwoven fiber material having sound absorbing particles embedded therein, or a combination thereof.

[0053] Embodiment 10 is the absorber of any one of embodiments 1 to 9, wherein the absorber has a flow resistance in the range of about 1000 mks rayl / m to about 50000 mks rayl / m, optionally about 4000 mks rayl / m to about 6000 mks rayl / m.

[0054] An eleventh embodiment is the sound absorber according to any one of the first to tenth embodiments, wherein the sound absorbing material has a thickness in the range of about 0.5 mm to about 200 mm, optionally 5 mm to about 50 mm.

[0055] A twelfth embodiment is the sound absorber according to any one of the first to eleventh embodiments, in which the sound absorbing material has a length along the longitudinal direction in the range of about 3 mm to about 2.5 m.

[0056] A thirteenth embodiment is the sound absorber according to any one of the first to twelfth embodiments, in which the sound absorbing material has a width in the range of about 5 mm to about 200 mm.

[0057] A fourteenth embodiment is the sound absorber according to any one of the first to thirteenth embodiments, further comprising an adhesive layer disposed on the flexible sheet-like substrate.

[0058] A fifteenth embodiment is a sound absorber assembly comprising a plurality of sound absorbers according to any one of the first to fourteenth embodiments, in which the sound absorbing materials of adjacent sound absorbers are separated by a gap.

[0059] Embodiment 16 is the sound absorber assembly of embodiment 15, wherein the multiple sound absorbers are connected by connecting portions.

[0060] Embodiment 17 is the sound absorber assembly of embodiment 16, wherein the connecting portion is substantially free of sound absorbing material.

[0061] An eighteenth embodiment is a pneumatic tire, an annular tread portion extending in the circumferential direction; an array of individual sound absorbers, at least one of which is the sound absorber of any one of embodiments 1-14 or the sound absorber assembly of any one of embodiments 15-17; and Equipped with A pneumatic tire having individual sound absorbers each attached to an inner surface of the annular tread, the array of individual sound absorbers being distributed circumferentially about the tread.

[0062] Embodiment 19 is the pneumatic tire according to embodiment 18, wherein the flexible sheet-like substrate of the at least one sound absorber extends along the circumferential direction of the tread portion.

[0063] Embodiment 20 is a pneumatic tire according to embodiment 18 or 19, wherein each individual sound absorber is attached to the inner surface of the annular tread portion via an adhesive layer.

[0064] Embodiment 21 is a pneumatic tire according to any one of embodiments 18 to 20, wherein the array of individual sound absorbers includes at least two, at least three, at least four, at least five, or optionally at least six sound absorbers.

[0065] Embodiment 22 is a pneumatic tire according to any one of embodiments 18 to 21, in which the array of individual sound absorbing bodies has a total length along the circumferential direction of the tread portion that is in the range of 1% to 100% of the circumferential length of the inner surface of the tread portion.

[0066] Embodiment 23 is a pneumatic tire according to any one of embodiments 18 to 22, in which the sound-absorbing materials of adjacent sound-absorbing bodies are separated by a gap, and the gap has a length along the circumferential direction of the tread portion that is in the range of 1% to 99% of the circumferential length of the inner surface of the tread portion.

[0067] A twenty-fourth embodiment is a wheel rim, a circumferentially extending annular rim surface; an array of individual sound absorbers, at least one of which is the sound absorber of any one of embodiments 1-14 or the sound absorber assembly of any one of embodiments 15-17; and Equipped with A wheel rim having individual sound absorbers each attached to an annular rim surface, the array of individual sound absorbers being distributed circumferentially along the annular rim surface.

[0068] Embodiment 25 is a wheel rim according to embodiment 24, wherein the flexible sheet substrate of the at least one sound absorber extends circumferentially along the annular rim surface.

[0069] Embodiment 26 is a wheel rim according to embodiment 24 or 25, wherein each individual sound absorber is attached to the inner surface of the annular rim surface via an adhesive layer.

[0070] Embodiment 27 is a wheel rim according to any one of embodiments 24 to 26, wherein the array of individual sound absorbers comprises at least two, at least three, at least four, at least five, or optionally at least six sound absorbers.

[0071] Embodiment 28 is a wheel rim according to any one of embodiments 24 to 27, wherein the array of individual sound absorbers has a total length along the circumferential direction of the annular rim surface in the range of 1% to 100% of the circumferential length of the annular rim surface.

[0072] Embodiment 29 is a wheel rim according to any one of embodiments 24 to 28, wherein the sound absorbing materials of adjacent sound absorbers are separated by a gap, the gap having a length along the circumferential direction of the annular rim surface in the range of 1% to 99% of the circumferential length of the annular rim surface.

[0073] A 30th embodiment is a wheel comprising the pneumatic tire according to any one of the 18th to 23rd embodiments.

[0074] Embodiment 31 is a wheel comprising the wheel rim according to any one of embodiments 24 to 29.

[0075] Embodiment 32 is a method for reducing tire cavity noise, comprising: (i) attaching an array of discrete sound absorbers to at least one of an inner surface of an annular tread portion of a pneumatic tire, and (ii) an annular rim surface of a wheel rim; A pneumatic tire is mounted on the wheel rim to form an enclosed tire cavity; At least one of the sound absorbers is the sound absorber according to any one of embodiments 1 to 14 or the sound absorber assembly according to any one of embodiments 15 to 17. This is the method.

[0076] Embodiment 33 is the method of embodiment 32, further comprising mounting at least one of the pneumatic tire and the wheel rim to the vehicle.

[0077] Embodiment 34 is the method of embodiment 33, wherein the motor vehicle includes at least one of a car, a bus, a truck, or a trailer.

[0078] The operation of the present disclosure will be further described with reference to the following detailed examples. These examples are provided to further illustrate various specific preferred embodiments and techniques. However, it should be understood that many variations and modifications can be made while remaining within the scope of the present disclosure. EXAMPLES

[0079] These examples are merely illustrative and are not intended to unduly limit the scope of the appended claims. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the present disclosure are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible. However, any numerical value inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. At the very least, each numerical parameter should be construed by at least applying ordinary rounding techniques in light of the number of reported significant digits, but this is not intended to limit the application of the doctrine of equivalents to the scope of the claims.

[0080] Test Method To evaluate the performance of different acoustic treatments, an acoustic test method called the "Tire Cavity Resonance Tube" has been developed. In this test, a straight tube with an inner cross section of 20 cm x 20 cm is used to simulate a half tire cavity. The length of the straight tube is therefore equal to half the average length of the annular tire cavity. The length of the straight tube is directly related to the resonant frequency of the tire cavity, which is

number

[0081] FIG. 8 is a schematic front view of the acoustic test setup. One end of the straight tube is closed and the other end is closed by a piston panel. The position of the piston panel 86 can be adjusted according to different tire sizes. The piston panel is equipped with an accelerometer 82 and a microphone 86 mounted at the center of the piston panel. During the test, a pulse force is applied to the center of the piston panel using a force hammer 86. The acceleration response and the sound pressure response at the center of the piston are measured by the accelerometer 82 and the microphone 86, respectively. The amplitude of the frequency response function between the sound pressure response and the acceleration response is finally determined and used to calculate the loss factor at the first cavity mode. The loss factor is calculated based on the "half power" method according to the attenuation measurement standard ISO 16940. The higher the loss factor, the greater the energy dissipation introduced by the corresponding acoustic treatment, i.e., the sound absorber 20a / 20b arranged in the tube.

[0082] Examples and Comparative Examples To compare the acoustic performance of the individual sound absorbers of the present disclosure with typical PU foam solutions on the market, the following examples and comparative examples are tested. The benchmark is when the tube has no acoustic treatment. Comparative example 1 uses a continuous layer of PU foam bonded to the bottom side of a straight tube. The longitudinal length, width and height of the PU foam are 1 m, 150 mm and 25 mm, respectively. The PU foam has a load of 50 kg / m 3and has a flow resistance of 8000 mks rayl / m. Comparative Example 2 uses the same PU foam material as Comparative Example 1. In Comparative Example 2, nine PU foam members are evenly distributed in the tube length direction and bonded to the bottom surface of the straight tube. The longitudinal length, width, and height of each PU foam member are 70 mm, 150 mm, and 25 mm. The gap between two adjacent PU foam members is 10 mm. Comparative Example 3 uses the same PU foam material as Comparative Example 1. In Comparative Example 3, the thickness of the continuous PU foam layer is increased to 40 mm.

[0083] Example 1 uses the individual sound absorber(s) of the present disclosure. An assembly of nine individual sound absorbers is bonded to the bottom surface of a tube. Each sound absorber has the same construction. The screen material is made from a 0.1 mm TPU film. It is 60 g / m 2 It has an areal density of 1000 rayl / m and is air impermeable. It will be appreciated that the air impermeable screen material can increase the low frequency absorption of the sound absorbing material. The sound absorbing material is made from a polyester fiber material. It has a flow resistance of 6000 rayl / m and a tensile strength of 400 g / m 2 The sound absorbing material has an areal density of 70 mm, 150 mm, and 25 mm in length, width, and height, respectively. The substrate is made of a 0.1 mm PU film. The substrate has a density of 60 g / m 2 The screen material and the sound absorbing material are not attached or bonded, but a loose connection is introduced between them, which further increases the low frequency absorption. The gap between two adjacent sound absorbers is 10 mm.

[0084] Example 2 uses the same individual layout, the same screen material, and the same substrate as Example 1. Unlike Example 1, the sound absorber of Example 2 in each absorber patch is composed of two layers of different sound materials. The top layer facing the screen material is a 13 mm thick polypropylene fiber layer. It has a flow resistance of 1100 mks rayl / m and a stiffness of 96 g / m 2The bottom layer facing the substrate is a 12 mm thick polyester fiber layer. It has a flow resistance of 5000 mks rayl / m and a surface density of 300 g / m 2 The top layer has an areal density of 1000 nm. The top layer has a lower flow resistance than the bottom layer, which is beneficial for low frequency absorption. When the sound absorber is bonded to the tire tread, the bottom layer provides a rigid resistance to centrifugal forces when the wheel is rotating. The top and bottom layers were not bonded.

[0085] Test results The loss factor in the first cavity mode of each case was measured and used for comparison. The test results are listed in Table 1 below. The total weight of each case is listed in the third column of the table. By comparing Comparative Example 1 with Example 1 or Example 2, it was found that the individual sound absorber of the present disclosure can achieve a 78% increase in loss factor, showing better acoustic performance than the typical PU foam solution on the market. In addition to the acoustic performance, the individual sound absorber of the present disclosure can achieve a total weight reduction of 66.5%, which is beneficial for the fuel efficiency of the tire. By comparing Comparative Example 2 with Example 1 or Example 2, it was found that even with the same layout, the individual sound absorber(s) of the present disclosure show a much higher loss factor than the individual PU member. By comparing Comparative Example 3 with Example 1 or Example 2, it was found that even if the thickness of the continuous PU foam layer is increased to 40 mm, the loss factor is still lower than the individual sound absorber.

[0086] [Table 1] _

[0087] Throughout this specification, reference to "one embodiment," "a particular embodiment," "one or more embodiments," or "an embodiment" means that the particular feature, structure, material, or characteristic described in connection with that embodiment is included in at least one of the particular exemplary embodiments of the disclosure, regardless of whether the term "embodiment" includes the term "exemplary." Thus, the appearances of phrases such as "in one or more embodiments," "in a particular embodiment," "in one embodiment," or "in an embodiment" in various places throughout this specification do not necessarily refer to the same particular exemplary embodiments of the disclosure. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.

[0088] Although certain exemplary embodiments have been described in detail herein, it will be understood that those skilled in the art, upon understanding the above description, can easily conceive of modifications, variations, and equivalents of these embodiments. It is therefore to be understood that the present disclosure is not to be unduly limited to the exemplary embodiments described thus far. In particular, as used herein, the recitation of numerical ranges by endpoints is intended to include all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5). In addition, all numbers used herein are intended to be modified by the term "about." Furthermore, various exemplary embodiments have been described. These and other embodiments are within the scope of the following claims.

Claims

1. A sound absorbing body, A flexible sheet-like substrate; A sheet-like screen material; A sound-absorbing material is disposed in a closed space formed by the sheet-like base material and the sheet-like screen material, and extends along a longitudinal direction of the sound-absorbing body; A sound absorbing body comprising:

2. 2. The sound absorber according to claim 1, wherein the flexible sheet-like substrate has a stretchability along the longitudinal direction of about 105% or more.

3. 2. The sound absorber of claim 1, wherein one or more ventilation holes are formed on the sheet screen material.

4. 2. The sound absorber of claim 1, wherein the sound absorbing material comprises at least one of polyurethane (PU) foam, glass fiber material, mineral fiber material, polyester fiber material, polypropylene fiber material, non-woven fiber material with embedded sound absorbing particles, or combinations thereof.

5. 10. The sound absorber of claim 1, wherein the sound absorbing material has a flow resistance in the range of about 1000 mks rayl / m to about 50000 mks rayl / m.

6. The sound absorber according to claim 1 , further comprising an adhesive layer disposed on the flexible sheet-like substrate.

7. 7. A sound absorber assembly comprising a plurality of sound absorbers according to any one of claims 1 to 6, wherein the sound absorbing material of adjacent sound absorbers is separated by a gap.

8. The sound absorber assembly according to claim 7 , wherein the plurality of sound absorbers are connected by connecting portions.

9. A pneumatic tire, an annular tread portion extending in the circumferential direction; an array of individual sound absorbers, at least one of which is a sound absorber according to any one of claims 1 to 6 or a sound absorber assembly according to claim 7 or 8; and Equipped with each of the individual sound absorbers is attached to an inner surface of the annular tread portion, and the array of individual sound absorbers is distributed along the circumferential direction of the tread portion; Pneumatic tires.

10. 10. The pneumatic tire of claim 9, wherein each of the individual sound absorbers is attached to the inner surface of the annular tread portion via an adhesive layer.

11. A wheel rim, comprising: a circumferentially extending annular rim surface; an array of individual sound absorbers, at least one of which is a sound absorber according to any one of claims 1 to 8 or a sound absorber assembly according to claim 9; Equipped with each of the individual sound absorbers is attached to the annular rim surface, and the array of individual sound absorbers is distributed along the circumferential direction of the annular rim surface; Wheel rim.

12. 12. A wheel rim according to claim 11, wherein each of the individual sound absorbers is attached to the inner surface of the annular rim surface via an adhesive layer.

13. A wheel comprising at least one of the pneumatic tire according to claim 9 and the wheel rim according to claim 11.

14. 1. A method for reducing tire cavity noise, comprising: (i) an inner surface of an annular tread portion of a pneumatic tire; and (ii) an annular rim surface of a wheel rim, comprising: attaching an array of individual sound absorbers to at least one of the following: the pneumatic tire is mounted to the wheel rim to form an enclosed tire cavity; At least one of the sound absorbers is a sound absorber according to any one of claims 1 to 6, or a sound absorber assembly according to claim 7 or 8. method.

15. 15. The method of claim 14, further comprising mounting at least one of the pneumatic tire and the wheel rim to a vehicle.

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