Tire cavity resonant sound absorber

Abstract

1. A tire comprising a tread portion, a bead portion, and a sidewall portion extending between the bead portion and the tread portion, the tread portion, the bead portion, and the sidewall portion defining an internal cavity of the tire, the tire further comprising a sealant layer disposed on the tread portion of the tire in the internal cavity of the tire, and a silicone foam noise reduction layer disposed on the sealant layer in the internal cavity of the tire.

Description

Technical Field

[0001] The present disclosure relates to noise reduction and improvement of self-sealing in tires.

Background Art

[0002] Tires are used in various vehicles under various conditions. Under some operating conditions, tires can produce undesirable levels of noise, which can have an adverse effect on the driver or passengers. For the purpose of reducing tire noise, a noise absorption layer or a noise reduction layer may be provided inside the tire.

[0003] Some tires have a sealant layer designed to automatically seal puncture holes in the tire. Such tires are sometimes referred to as "self-sealing" tires. The sealant layer may be a viscous coating inside the tire. The purpose of the sealant layer is to maintain the integrity of the tire even when the object that caused the puncture comes out of the tire during a puncture.

[0004] It has been impossible to provide a self-sealing tire with good noise absorption without impairing the sealing performance. Using a noise reduction layer together with a sealant layer brings a number of problems. When the noise reduction layer adheres to the sealant layer, the noise reduction layer may be deformed and its performance may deteriorate. This can occur, for example, when the tire is affected and deformed, and the noise reduction layer is pushed into the sealant layer.

[0005] Similarly, the noise reduction layer may adhere to the sealant layer and prevent the sealant layer from flowing to seal the puncture hole. This can occur when a part of the noise reduction layer inhibits the flow of the sealant layer to the puncture hole. A small portion of the noise reduction layer may be separated from the rest of the noise reduction layer and sucked into the puncture hole, preventing the sealant layer from sealing the puncture hole. [Overview of the project]

[0006] The tire described herein has been found to overcome the disadvantages associated with the prior art. The tire described herein provides improved noise reduction performance without compromising self-sealing performance. The tire described herein improves noise reduction and sealing performance without increasing the complexity of the internal design of the tire cavity.

[0007] The present disclosure relates to a tire. The tire may comprise a tread portion, a bead portion, and a sidewall portion. The sidewall portion may extend between the bead portion and the tread portion. The tread portion, bead portion, and sidewall portion may define an internal cavity of the tire. The tire may further comprise a sealant layer disposed on the tread portion of the tire in the internal cavity of the tire. The tire may further comprise a silicone foam noise reduction layer disposed on the sealant layer in the internal cavity of the tire.

[0008] The tire may be a pneumatic tire, such as those used in vehicles including passenger cars, light cargo vehicles, and heavy cargo vehicles. The tire may be mounted on a hub and filled with compressed air. The bead may be the innermost radial portion of the tire. The bead may be configured to provide rigidity to the tire and allow the tire to be mounted to the wheel hub. The tread may have a tread on its outer surface to contact the road surface and provide grip. The sidewall may have two sidewall portions on either side of the tread, extending between the tread and the bead.

[0009] The tire may be a self-sealing tire. The tire may be configured to automatically seal puncture holes. The sealant layer may be configured to provide this self-sealing capability. The sealant layer may be configured to automatically seal puncture holes that pass through the tread, for example, puncture holes in the range of 0 to 5 mm in diameter.

[0010] The sealant layer may contain, or consist of, a viscous fluid configured to flow into the puncture hole or hole in the tread, act to seal the puncture hole or hole, and prevent the loss of air through the puncture hole or hole.

[0011] The sealant layer may be a homogeneous layer. The sealant layer may be formed from a single homogeneous composition. The sealant layer may be configured to adhere (for example, directly) to the tread and noise reduction layer.

[0012] The sealant layer may be in direct contact with the tire tread and the silicone foam noise reduction layer.

[0013] The sealant layer may be sandwiched between the tread portion and the silicone foam noise reduction layer without any intermediary.

[0014] For example, a tire does not need to have a separate adhesive layer in addition to the sealant layer and the silicone foam noise reduction layer.

[0015] The tire may have only a sealant layer and a silicone foam noise-reducing layer in its internal cavity.

[0016] The arrangement of this sealant layer and noise reduction layer eliminates the need for a separate adhesive or support layer, significantly simplifying the tire's structure.

[0017] The sealant layer is rated at 100°C for 50-1000 Pa·s (Pascal seconds (Nsm)). -2 The sealant layer may have a viscosity of 50, 100, 200, 400, 600, or 800 Pa·s, and / or the sealant layer may have a viscosity of less than 1000, 800, 600, 400, 200, or 100 Pa·s at 100°C.

[0018] Viscosity is measured according to ASTM D5099.

[0019] The sealant layer may have a thickness of 1 to 6 mm. The sealant layer may have a thickness greater than 1 mm, 2 mm, 3 mm, 4 mm, or 5 mm, and / or the sealant layer may have a thickness of less than 6 mm, 5 mm, 4 mm, 3 mm, or 2 mm.

[0020] The sealant layer may have an adhesiveness of 0.1 to 25 N. The sealant layer may have an adhesiveness greater than 0.1, 2, 5, 10, 15, or 20 N, and / or the sealant layer may have an adhesiveness less than 25, 20, 15, 10, 5, 2, or 0.1 N.

[0021] Adhesion is measured by a probe tack test using a plunger with a diameter of 25-30 mm, a probe with a diameter of 30 mm, a preload of 0.5 N, a residence time of 30 seconds, and a desorption rate of 2000 mm / min.

[0022] The sealant layer may contain rubber-based materials or may consist solely of rubber-based materials. The sealant layer may be a composite sealant layer.

[0023] The sealant layer may contain or consist of butyl rubber (i.e., any butyric rubber), a plasticizer, and a tackifier resin. The butyl rubber may be halobutyl rubber.

[0024] The sealant layer may contain butyl rubber. The sealant layer may contain 100 to 400 PHR of plasticizer (PHR stands for parts per hundred parts of rubber). The sealant layer may contain 10 to 80 PHR of tackifier resin.

[0025] The sealant layer may contain butyl rubber, 100 to 400 PHR of a plasticizer, and 10 to 80 PHR of a tackifier resin, or may consist of these materials.

[0026] The term PHR refers to the ratio of a constituent material to 100 parts of rubber. For example, a 50 PHR component requires 50 parts of that component per 100 parts of rubber. PHR may be based on weight or volume.

[0027] During use, as the road surface affects the tread portion of the tire, the air inside the cavity and / or the tire itself may vibrate. In a tire without a noise reduction layer, this vibration may be transmitted as noise into the vehicle interior. This noise can typically be in the frequency band of 200 - 250 Hz. In the case of a tire with a rim diameter larger than 19 inches, the frequency band may shift to a frequency below 200 Hz, such as 170 - 220 Hz or 160 - 210 Hz.

[0028] The tire has a noise reduction layer. The noise reduction layer is a silicone foam noise reduction layer.

[0029] Surprisingly, it has been found that using a silicone foam in the noise reduction layer overcomes the demerits associated with existing configurations using polyurethane (PU) or ethylene propylene diene monomer (EPDM) foam. The silicone foam noise reduction layer improves noise adsorption while its low adhesiveness enables the normal functioning of the sealant.

[0030] The silicone foam noise reduction layer is a cellular silicone foam having an open cell structure. The use of an open cell structure improves the adhesion of the noise reduction layer to the sealant layer.

[0031] The use of an open-cell structure enables mechanical adhesion. That is, the sealant can penetrate the open-cell structure of the silicone foam while the silicone foam remains in place within the tire. This is achieved without significant sealant adhesion to the surface of the silicone foam itself. In other words, the silicone foam does not obstruct the flow of the sealant, and therefore the sealant can freely flow into the puncture hole and perform its sealing function.

[0032] The silicone foam noise reduction layer may have an operating temperature range from -40°C to over 150°C, which may be measured according to the ASTM D 1056 standard.

[0033] The silicone foam noise reduction layer has a density of 105 kg / m². 3 It may have a density of less than 60 kg / m³. The silicone foam noise reduction layer has a density of 60 kg / m³. 3 It may have a density of less than 1.5. This may be measured according to the ASTM D 1056 standard.

[0034] The silicone foam noise reduction layer may have a tensile strength greater than 70 kPa. This may be measured according to the ASTM D 412 standard.

[0035] The silicone foam noise reduction layer may have an ultimate elongation greater than 40%. This may be measured according to the ASTM D 412 standard.

[0036] The silicone foam noise reduction layer may have a compression set of less than 5%. The silicone foam noise reduction layer may have a compression set of less than 2%. This may be measured according to ASTM D 1056.

[0037] The silicone foam noise reduction layer may have a temperature resistance of -40 to +150°C. The silicone foam noise reduction layer may also have a temperature resistance of -40 to +100°C. This may be measured according to the ASTM D 1056 standard.

[0038] The silicone foam noise reduction layer may have a width of 50 to 150 mm. The width may be measured in a direction parallel to the tire's axis of rotation.

[0039] The silicone foam noise reduction layer may have a thickness of 15-40 mm, 15-30 mm, 20-35 mm, or 25-30 mm. The thickness may extend in the radial direction of the tire.

[0040] The silicone foam noise reduction layer may extend over 80-100% or 90-100% of the inner circumference of the tire.

[0041] The silicone foam noise reduction layer may be cubic. The silicone foam noise reduction layer may have a triangular or trapezoidal cross-section. The silicone foam noise reduction layer may be tapered. The silicone foam noise reduction layer may have a varying width or thickness around the perimeter of the tire. The silicone foam noise reduction layer may have an uneven thickness or width around the perimeter of the tire.

[0042] The silicone foam noise reduction layer may be located in the center of the sealant layer. The silicone foam noise reduction layer may be located centrally and symmetrically with respect to the tire's center plane. This may improve the tire's balance.

[0043] Further relating to this disclosure is a vehicle equipped with tires as described herein. [Brief explanation of the drawing]

[0044] [Figure 1] This is a partial cross-sectional view of a tire having a sealant layer and a silicone foam noise reduction layer. [Figure 2] This graph shows the noise absorption performance of a tire across a certain frequency range. [Modes for carrying out the invention]

[0045] Figure 1 below shows a cross-section of tire 10. Tire 10 is a pneumatic tire of the type used in passenger cars and other vehicles. Figure 1 is a partial cross-sectional view showing one side of tire 10.

[0046] The tire 10 includes a tread portion 12 positioned to contact the road surface. The tread portion 12 is located radially outward of the tire 10. The tire 10 also includes a bead portion 14. The bead portion 14 is located radially inward of the tire 10. The bead portion 14 is positioned to connect the tire to a hub or wheel (not shown). The tire 10 also includes a sidewall portion 16. The sidewall portion 16 extends between the tread portion 12 and the bead portion 14, connecting them. The tread portion 12, the bead portion 14, and the sidewall portion 16 collectively define the internal cavity of the tire 10. The cavity of the tire is pressurized during use.

[0047] The tread portion 12 has a tread designed to contact and grip the road surface during use. The sealant layer 18 is located on the inner surface of the tread portion 12. The sealant layer 18 is located so as to cover at least a portion, or possibly substantially the entire, of the inner surface of the tread 12. The sealant layer 18 is configured to repair damage to the tread 12 during use, for example, due to a puncture.

[0048] The sealant layer 18 achieves this through its viscous and adhesive properties, allowing it to flow into puncture holes or holes in the tread 12, seal the puncture holes, and prevent pressure loss in the tire 10. The sealant layer 18 can act to seal puncture holes up to 5 mm in diameter even after the object that punctured the tire has been removed.

[0049] The sealant used to form the sealant layer 18 has tackiness that ensures adhesion to both the inside of the tread portion 12 of the tire 10 and the noise reduction layer 20 without requiring an additional adhesive layer. This means that there are only two layers inside the tire tread 12, instead of three.

[0050] Examples of properties suitable for use as a sealant layer that provides appropriate sealing performance are shown in Table 1 below. [Table 1]

[0051] In some cases, the adhesive strength may be between 5 and 20 N.

[0052] The bead portion 14 is located inside the cavity formed within the bead portion 14 and includes, for example, a reinforcing member 22 that provides strength and rigidity to the tire 10.

[0053] The sidewall section 16 has sidewalls on both sides of the tire 10.

[0054] The tire 10 further comprises a noise reduction layer 20. The noise reduction layer 20 is located on the sealant layer 18, such that the sealant layer 18 is sandwiched between the tread portion 12 and the noise reduction layer 20. In this example, the noise reduction layer 20 is centrally located with respect to the center plane of the tire 10. This improves the balance and rotational stability of the tire 10. In the example in Figure 1, the noise reduction layer 20 extends over most of the sealant layer 18 (for example, in a direction parallel to the rotation axis of the tire and / or in the circumferential direction). In other examples, the noise reduction layer 20 may extend over the entire sealant layer 18 or over only a portion of the sealant layer 18.

[0055] In this example, a noise reduction layer 20 that is substantially cubic in shape is used. This configuration is convenient because it allows the noise reduction layer 20 to be manufactured in a roll and transported. However, in other examples, noise reduction layers of alternative shapes may be used. For example, the noise reduction layer may have a triangular or trapezoidal cross-section, or it may have surface waves or surface changes in a thickness parallel to the radius of the tire.

[0056] The noise reduction layer 20 is configured to absorb vibrations of the tire 10 during use, thereby reducing vibration noise from the tire 10. This noise is generated by the air inside the tire 10, which is vibrated by external inputs such as contact with the road surface and deformation of the tire tread 12. Most of this excitation and noise, typically called tire cavity noise, falls within the frequency range of 200 Hz to 250 Hz.

[0057] In this example, the noise reduction layer 20 is made from silicone foam. Silicone foam has low tackiness while also possessing good noise reduction properties. This means that the silicone foam provides good noise absorption and, critically, does not interfere with the sealing properties of the sealant layer. Thus, the use of silicone foam provides the tire 10 with both good self-sealing and noise reduction performance.

[0058] In the example shown in Figure 1, open-cell silicone foam is used as the noise reduction layer 20. The use of open-cell silicone foam allows the sealant material to penetrate into the open-cell structure of the silicone foam, thus achieving "mechanical adhesion." Here, the silicone foam is bonded to the sealant by its penetration into the foam structure. This improves overall adhesion in both the lateral and radial directions without the sealant adhering to the surface of the foam itself. This minimizes foam movement even during significant deformation of the tire 10. However, the sealant still flows freely within the silicone foam, and therefore, the sealing performance is largely unaffected.

[0059] Low-density silicone foam is used, which reduces the overall weight of the tire.

[0060] Sealing tests were conducted on tires with sealant only, tires with sealant and a PU foam noise reduction layer, and tires with sealant and a silicone foam noise reduction layer. The results are shown in Table 2 below.

[0061] The test conditions for indoor testing were as follows: Tire size: 215 / 65 R17; Inflation pressure: 2.5 bar; Test speed: 100 km / h; Tire load: 500 kg; Test drum diameter: 2 m; Test room temperature: 38°C.

[0062] The test conditions for the outdoor tests were as follows: Tire size: a.) 215 / 65 R17 and b.) 235 / 55 R19; Inflation pressure: 2.5 bar; Test speed: 100 km / h; Tire load: 500 kg; Test vehicle: VW Tiguan or equivalent in the same compact SUV segment; Ambient temperature range 1: Tested at -25°C to -5°C (tire size a.) and Ambient temperature range 2: Tested at 20°C to 40°C (tire size b.).

[0063] The passing criterion for the test was that the tire, after being driven 1000 km with nails embedded in the tread, then having the nails removed, being driven an additional 400 km, and being stored for 14 days, had a minimum residual inflation pressure of 1.8 bar. As shown in the table, the use of the silicone foam noise reduction layer resulted in good sealing performance. On the other hand, the use of the PU foam noise reduction layer did not result in good sealing performance. This is because the PU foam noise reduction layer was adversely affected by the disadvantages described herein. That is, the PU foam noise reduction layer may have prevented the sealant layer from functioning properly, thereby suppressing proper sealing. The silicone foam noise reduction layer, however, did not interfere with the performance of the sealant layer. [Table 2]

[0064] Next, Figure 2 and Table 3 below compare the absorption (i.e., absorption coefficient or absorptivity) of a 25mm thick silicone foam noise reduction layer with that of similar 25mm and 30mm PU foam noise reduction layers of the same diameter. Figure 2 plots the noise absorption rates for the three noise reduction layers over a frequency range of 100–350Hz. Table 3 below shows typical noise reduction values ​​over the 200–250Hz range, which is the main frequency range for noise generated by tire cavity vibration. It can be seen that the silicone foam noise reduction layer performs better than not only PU noise reduction layers of the corresponding dimensions, but also larger PU noise reduction layers.

[0065] Absorption is measured according to ISO 10534-2. [Table 3]

[0066] Table 4 shows the difference in noise levels in decibels during outdoor road tests. These outdoor road tests are so-called in-cab noise tests, conducted by driving a compact SUV vehicle on rough roads at a constant speed. The dB(A) values ​​are the arithmetic average of measurements taken from microphones positioned in the driver's left ear and the passenger's right ear. The test tire size was 235 / 55 R19.

[0067] The results for a 25mm thick silicone foam noise reduction layer are compared with those for a corresponding tire with a 30mm thick PU foam noise reduction layer. The results are shown as a reduction in decibel levels, relative to the same tire without the foam noise reduction layer. As shown in the table, the silicone foam noise absorption layer is significantly more effective than the PU foam noise absorption layer. [Table 4]

[0068] Improved performance of the silicone foam noise reduction layer allows for a reduction in the thickness of the noise reduction layer in tires.

[0069] Silicone foam suitable for use as a noise reduction layer may have a wide operating temperature range (e.g., -40 to +100°C or +150°C). Silicone foam may also have a low compression set value, for example, less than 5%, or more preferably less than 2%.

[0070] A suitable example of silicone foam for use in a silicone foam noise reduction layer is Rogers® MF1-35®.

[0071] The appropriate properties of silicone foam for use as a silicone foam noise reduction layer are given in Table 5. [Table 5]

[0072] The indicated compression set value indicates a material that can return to its initial shape after being compressed by a load. This is preferable because it allows silicone foam to nearly return to its initial thickness and shape after deformation.

[0073] The present invention has been described above purely as an example. Minor modifications to the invention may be made within the claims appended herein. Furthermore, it will be understood that the present invention is not in any way limited to the combinations of features shown in the examples described herein. Features disclosed in one example can be combined with features disclosed in further examples.

Claims

1. It is a tire, The tread section and The bead section and, A sidewall portion extending between the bead portion and the tread portion, Equipped with, The tread portion, bead portion, and sidewall portion define the internal cavity of the tire. The aforementioned tire is A sealant layer is disposed on the tread portion of the tire in the internal cavity of the tire, A silicone foam noise reduction layer is disposed on the sealant layer in the internal cavity of the tire, Furthermore, The sealant layer is made of a rubber-based material. The sealant layer is sandwiched between the tread portion and the silicone foam noise reduction layer without any intermediary in the tire.

2. The tire according to claim 1, wherein the silicone foam noise reduction layer is a cellular silicone foam having an open-cell structure.

3. The tire according to claim 1, wherein the silicone foam noise reduction layer has an operating temperature range of -40°C to over 150°C.

4. The aforementioned silicone foam noise reduction layer is 105 kg / m ３ Density less than, Tensile strength greater than 70 kPa, Extreme growth of more than 40%, Settling set of less than 5%, and / or Temperature resistance from -40 to +200°C A tire according to claim 1, having the following features.

5. The aforementioned silicone foam noise reduction layer has a density of 60 kg / m². ３ The tire according to claim 1, having a density of less than 1.

6. The tire according to claim 1, wherein the silicone foam noise reduction layer has a compression set of less than 2%.

7. The tire according to claim 1, wherein the silicone foam noise-reducing layer has a width of 50 to 150 mm, a thickness of 15 to 30 mm, and / or extends over 90 to 100% of the inner circumference of the tire.

8. The tire according to claim 1, wherein the silicone foam noise reduction layer is located in the center of the sealant layer.

9. The tire according to claim 1, wherein the sealant layer is formed from a single homogeneous composition and is configured to adhere to the tread portion and the noise reduction layer.

10. The tire according to claim 1, wherein the internal cavity of the tire comprises only the sealant layer and the silicone foam noise reduction layer.

11. The tire according to claim 1, wherein the tire does not include a separate adhesive layer in addition to the sealant layer and the silicone foam noise reduction layer.

12. The tire according to claim 1, wherein the sealant layer has a viscosity of 50 to 1000 Pa·s at 100°C, a layer thickness of 1 to 6 mm, and / or an adhesiveness of 0.1 to 25 N.

13. The tire according to claim 1, wherein the sealant layer comprises butyl rubber, a plasticizer, and a tackifier resin.

14. A vehicle equipped with the tire described in any one of claims 1 to 13.

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