JP2009023609A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of effectively radiating heat generated inside a tread portion, based on the premise of effective reduction in road noise. <P>SOLUTION: This pneumatic tire 1 is formed by disposing one band-like sound absorbing layer 11 made of a porous material on an internal surface of an inner liner 10. The sound absorbing layer 11 has a thick-wall portion 13 with a relatively large thickness and a thin-wall portion 14 with a smaller thickness than that of the thick-wall portion 13. The thin-wall portion 14 is a pneumatic tire passing through a belt end position 12. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire in which a band-like sound absorbing layer made of a porous material is disposed on the inner surface of an inner liner, and in particular, prevents accumulation of heat generated inside the tread portion of the tire.

  A pneumatic tire assembled in a rim and attached to a vehicle generates a cavity resonance of air filled in the tire lumen when the tread portion vibrates against the road surface unevenness while the vehicle is running. This cavity resonance is a main cause of so-called road noise, and many of the resonance frequencies exist in the range of 180 to 300 Hz. When road noise is transmitted to the vehicle interior, it takes a sharp and high peak value, unlike noise in other frequency bands, and thus becomes annoying noise for passengers in the vehicle interior.

  In order to suppress such cavity resonance and reduce road noise, Patent Document 1 discloses a non-ring-shaped sound control using a sponge material in a tire lumen formed by a rim and a pneumatic tire bonded to the rim. The belt-like sheet is fixed in the tire circumferential direction, and the belt-like sheet has a volume S2 in which a ratio S2 / S1 to the total volume S1 of the tire lumen is 0.4% or more, and the sponge material The surface having a specific gravity of 0.005 to 0.06 and facing the tire lumen of the belt-shaped sheet is an uneven surface, and the uneven surface has a protruding convex portion and a concave concave portion. There has been proposed an assembly of a pneumatic tire and a rim, which is characterized by being repeatedly scattered with unevenness in the circumferential direction or the tire axial direction without being aligned.

Japanese Patent No. 3622957

  However, in the invention described in Patent Literature 1, although road noise during traveling can be effectively reduced, a belt-like sheet made of a so-called sponge material in which rubber or synthetic resin is foamed is used as an inner liner on the inner peripheral side of the tread portion. In addition, the belt-like sheet extends in the circumferential direction and is firmly attached, and the heat insulating function is also exhibited. Therefore, the heat generated in the tread portion is smoothly transferred into the lumen defined by the pneumatic tire and the rim. There was an inconvenience that it was impossible to dissipate.

  That is, the tread portion generates heat internally due to friction between the tread contact surface and the road surface, elastic deformation of the tread rubber, etc., but the divergence of this heat to the tire lumen is hindered by the belt-like sheet fixed to the inner liner. It has been. For this reason, the temperature of the tread portion rises excessively, and the carcass cord, the belt cord and the like are peeled off from the rubber material due to heat deterioration of the rubber material, and there is a high risk of causing a decrease in tire durability. It was. Such thermal deterioration is particularly serious when the tire rolls on a high-temperature road surface or when the tire rolls at high speed.

  Accordingly, it is an object of the present invention to solve these problems, and its purpose is to effectively dissipate heat generated inside the tread portion on the premise of effective reduction of road noise. It is to provide a pneumatic tire that can.

  In order to achieve the above object, the present invention provides a pneumatic tire in which a band-shaped sound absorbing layer made of a porous material is disposed on the inner surface of an inner liner, and the sound absorbing layer has a relatively large thickness. The pneumatic tire is characterized in that it includes a thin portion and a thin portion having a thickness smaller than that of the thick portion, and the thin portion passes through a belt end position. Thus, by providing the sound absorbing layer on the inner surface of the tire, much of the vibration energy of the filled air when the cavity resonance occurs in the tire lumen is converted to the internal vibration energy of the porous material constituting the sound absorbing layer. Cavity resonance can be effectively reduced by converting and consuming it as thermal energy. Further, by providing a thin portion having a relatively small thickness at the belt end position where the internal heat generation is particularly large, the generated heat can be smoothly dissipated from the thin portion into the lumen.

  Here, the “thickness” of the thick part and the thin part is a thickness calculated by averaging the thicknesses in the respective ranges of the thick part and the thin part. “Belt end position” refers to the application described in the next standard by attaching the tire to the standard rim (or “Approved Rim” or “Recommended Rim”) for the applicable size described in the following standard. The belt layer located on the innermost side in the tire radial direction when viewed in the cross section of the tire width direction in the ground contact state under the condition of applying the maximum load (maximum load capacity) and the air pressure corresponding to the maximum load in size The position corresponding to the intersection of the extended line of the perpendicular drawn from the edge in the tire width direction of the innermost belt layer to the inner surface of the inner liner and the inner surface of the tire, that is, the inner surface of the sound absorbing layer. The standard refers to an industrial standard effective in the region where tires are produced or used, for example, “Year Book” of The Tire and Rim Association Inc. in the United States, and The European Tire and Rim Technical Organization in Europe. "Standards Manual", and in Japan it is the "JATMA Year Book" of the Japan Automobile Tire Association. The air here can be replaced with an inert gas such as nitrogen gas.

  The thickness of the thin portion is preferably 75% or less of that of the thick portion.

  Furthermore, the length of the thin portion in the tire width direction is preferably 20 mm or more.

  Furthermore, it is preferable that the center position of the thin portion in the tire width direction coincides with the belt end position.

  Furthermore, it is preferable that the length of the thin portion in the tire width direction is the same over the tire circumferential direction.

  Furthermore, the thin portion preferably extends continuously in the tire circumferential direction.

  In addition, it is preferable that all thin portions pass through the belt end position.

  According to the present invention, the arrangement of the sound absorbing layer effectively reduces road noise, and the thin portion provided at an appropriate position of the sound absorbing layer effectively absorbs heat generated inside the tread portion. It is possible to dissipate heat.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a cross section in the tire width direction of a tire / rim assembly formed by mounting a typical pneumatic tire (hereinafter referred to as “tire”) according to the present invention on a standard rim, and shows the maximum load and the maximum load. FIG. 2 (a) is a developed view of the sound absorbing layer of the tire shown in FIG. 1, and FIG. 2 (b) is a diagram of FIG. 2 (a). It is an AA cross-sectional arrow view.

  As shown in FIG. 1, the pneumatic tire 1 of the present invention includes a tread portion 2 that contacts the road surface according to a conventional manner, a pair of sidewall portions 3 that extend inward in the tire radial direction from both side portions of the tread portion 2, and A tire main body 5 is configured by a pair of bead portions 4 provided on the inner side in the tire radial direction of each sidewall portion 3 and fitted to the rim R. Inside the tire body 5 is a toroidal structure between the bead cores 6 and 6 embedded in each bead to form a skeleton structure of the tire body 5, for example, a radial carcass 7 and a crown of the carcass 7. A belt 8 that reinforces the tread portion 2 is disposed on the outer peripheral side of the region. An air-impermeable inner liner 10 is disposed on the inner surface side of the tire body 5, that is, the side facing the tire lumen 9 defined by the tire 1 and the rim R.

  On the inner surface of the inner liner 10, a single band-like sound absorbing layer 11 made of a porous material is disposed over the entire circumference, so that the vibration of the filled air caused by the cavity resonance generated in the tire lumen 9. The energy is converted into the internal vibration energy of the porous material constituting the sound absorbing layer 11 and is consumed as heat energy, thereby reducing the cavity resonance sound.

  The porous material constituting the sound absorbing layer 11 is a foamed material having open cells or closed cells formed by foaming rubber or synthetic resin, or a woven material in which animal fibers, plant fibers, synthetic fibers, etc. are intertwined and integrated. Cloth, non-woven fabric, knitted fabric, or the like can be used. If, for example, synthetic rubber is used as the porous material, the heat-absorbing layer 11 can also be provided with excellent heat resistance and water resistance, and if an ether-based polyurethane foam is used, the foamed material is hardly hydrolyzed. it can.

  The sound absorbing layer 11 can be fixed to the inner liner 10. For this fixing, for example, heat welding, an adhesive, a double-sided tape, a hook-and-loop fastener, or the like can be used, and the sound absorbing layer is fixed in a raw tire state. In this case, vulcanization adhesion can be used.

  The main feature of the present invention is that, as shown in FIGS. 1 and 2, the sound absorbing layer 11 has a thick part 13 having a relatively large thickness and a smaller thickness than the thick part 13. A belt corresponding to an intersection of an extended line L of a perpendicular line extending from an edge in the tire width direction of the innermost belt layer to the inner surface of the inner liner 10 and the inner surface of the sound absorbing layer 11. Passing through end position 12.

  When the tire rolls under load, heat is generated inside due to friction between the tread contact surface and the road surface, elastic deformation of the tread rubber, and the like. In the case of a normal tire, this heat is dissipated into the air filled in the tire lumen, and the air is cooled by the rim, so that the temperature of the tread portion does not rise excessively. However, when a sound-absorbing layer made of a porous material is disposed on the inner surface of the tire for the purpose of reducing road noise, the porous material is also a high heat insulating material, so that heat generated inside the tread portion is transferred to the tire lumen. Heat dissipation is hindered by the sound absorbing layer, and as a result, the temperature of the tread portion may increase excessively. Such a temperature rise causes thermal deterioration of the rubber material constituting the tread portion, and carcass cords, belt cords and the like are peeled off from the rubber material, thereby reducing the durability of the tire.

  In contrast, in the tire according to the present invention, the sound absorbing layer 11 is provided with a thin portion 14 having a relatively small thickness, and heat generated in the tread portion 2 through the thin portion 14 is used to fill the air in the tire lumen 9. Heat can be radiated smoothly. Further, it is known that the heat generation inside the tread portion 2 is particularly large in the vicinity of the belt end position 12. Therefore, a sufficient heat radiation effect is obtained by arranging the thin portion 14 so as to pass through the belt end position 12. Thereby, it is possible to prevent an excessive increase in temperature of the tread portion 2 and maintain the durability of the tire.

  When the thin wall portion 14 is provided, the volume of the porous material is reduced, but the end surface of the porous material is exposed at the boundary between the thick wall portion 13 and the thin wall portion 14 by the thickness difference. Since the contact area between the sound absorbing layer 11 and the sound absorbing layer 11 increases as compared with the case where the thin portion 14 is not provided, the sound absorbing effect can be maintained equal to or higher.

  In order to ensure heat dissipation to the air filled in the tire lumen, a plurality of porous materials may be arranged apart from each other in the tire width direction and / or the tire circumferential direction, and heat may be released from these separated parts. However, in this case, since there are a plurality of sound absorbing layers, the process of attaching the porous material to the inner surface of the inner liner is complicated, and high application accuracy is required to dispose at a uniform interval. This results in increased manufacturing costs. In addition, if the spacing between the sound absorbing layers is not uniform, the uniformity of the tire is lowered. On the other hand, in the tire according to the present invention, the sound absorbing layer can be composed of one porous material, so that the uniformity can be kept high while being low in cost.

  The thickness of the thin portion 14 is preferably 75% or less of that of the thick portion 13. This is because if the thickness of the thin portion 14 exceeds 75% of that of the thick portion 13 at the belt end position 12, a sufficient heat dissipation effect may not be obtained.

  Furthermore, the length W of the thin portion 14 in the tire width direction is preferably 20 mm or more. This is because when the width of the thin portion 14 in the tire width direction is less than 20 mm, a sufficient heat dissipation effect cannot be obtained.

  Furthermore, it is preferable that the center position of the thin portion 14 in the tire width direction coincides with the belt end position 12. This is because heat generated in the vicinity of the belt end position 12 can be dissipated evenly inside and outside in the tire width direction, and the heat dissipating effect can be further enhanced.

  Further, the length W of the thin portion 14 in the tire width direction is preferably the same over the tire circumferential direction. This is because the mass of the sound absorbing layer 11 in the circumferential direction can be made uniform and deterioration of uniformity can be suppressed.

  Furthermore, it is preferable that the thin portion 14 extends continuously in the tire circumferential direction. This is because the heat radiation area of the thin portion 14 can be increased and the heat radiation effect can be further increased, and the mass of the sound absorbing layer 11 in the circumferential direction can be made uniform and deterioration of uniformity can be suppressed. Because.

  In addition, it is preferable that all the thin portions 14 pass through the belt end position 12. This is because the thin portion 14 corresponding to the belt end position 12 where heat is generated can be maximized, and more efficient heat dissipation can be obtained.

  Note that the above description shows only a part of the embodiment of the present invention, and these configurations can be combined with each other or various modifications can be made without departing from the gist of the present invention. . For example, the thickness of the thin portion 14 may be the same in the tire width direction as in the illustrated example, but is not limited thereto, and the thickness may be gradually reduced toward the center in the width direction of the thin portion 14. . Moreover, although illustration is abbreviate | omitted, the thin part 14 may exist discontinuously in the tire circumferential direction, and may extend in the shape of a curve or a zigzag in the tire circumferential direction.

  Next, tires according to the present invention were prototyped and performance evaluations were performed, which will be described below.

  The tire of Example 1 is a radial tire having a tire size of 215 / 45R17, and a polyethylene terephthalate (PET) nonwoven fabric having a fineness of 6 dtex, a thickness of 14 mm, and a width of 280 mm is formed on the inner peripheral surface of the inner liner as a sound absorbing layer. The circumference of the inner surface at the belt end position is 1850 mm. As shown in FIG. 1B, the sound absorbing layer has a tire width direction length of 20 mm and a thickness of 10 mm continuously passing through the belt end position (the thickness of the thin portion relative to the thickness of the thick portion is 71%), and the thin portion is arranged so that the belt end position is located at the center of the thin portion in the tire width direction. Further, all of this thin portion passes through the belt end position.

  The tire of Example 2 is a tire having the same configuration as the tire of Example 1 except that the thickness of the thin portion is different. The thickness of the thin part of the tire of Example 2 is 10.5 mm (the thickness of the thin part with respect to the thickness of the thick part is 75%).

  The tire of Example 3 is a tire having the same configuration as the tire of Example 1 except that the thickness of the thin portion is different. The thickness of the thin portion of the tire of Example 3 is 11.5 mm (the thickness of the thin portion relative to the thickness of the thick portion is 82%).

  The tire of Example 4 is a tire having the same configuration as the tire of Example 1 except that the thickness of the thin portion is different. The thickness of the thin portion of the tire of Example 4 is 12 mm (the thickness of the thin portion with respect to the thickness of the thick portion is 86%).

  For comparison, except that it does not have a sound absorbing layer, except that the tire of Conventional Example 1 having the same configuration as the tires of Examples 1 to 4 and the sound absorbing layer are not provided with a thin portion, The tire of Conventional Example 2 having the same configuration as the tires of Examples 1 to 4 was also prototyped.

  Each of the test tires is mounted on a rim of size 17 × 7 J to form a tire wheel, and the tire wheel is attached to a test vehicle, an air pressure of 210 kPa (relative pressure) and a tire load load of 3.92 kN are applied, and a speed of 60 km / The room noise when traveling on an asphalt road under the condition of h was measured. This measurement result was subjected to frequency analysis, and the suppression effect of the cavity resonance was evaluated based on the peak sound pressure level seen near 230 kHz. The evaluation results are shown in Table 1. The evaluation results in the table are expressed as an exponential ratio when the cavity resonance suppression effect of Conventional Example 2 in which the sound absorbing layer is provided is set to 100 with respect to the sound pressure level of Conventional Example 1 having no sound absorbing layer. The larger the value, the greater the cavity resonance suppression effect.

  In addition, a drum durability performance test was performed according to the high speed performance test B defined in JIS D4230, and durability was evaluated based on the number of steps until the tire failed from the vicinity of the belt end position. The evaluation results are shown in Table 1. In addition, the evaluation result in a table | surface is represented by the index ratio when the number of steps of the prior art example 1 is set to 100, and it is excellent in durability, so that a numerical value is large.

  From the results shown in Table 1, the tires of Examples 1 to 4 have significantly improved durability compared to the tire of Conventional Example 2 that does not have a thin portion while maintaining the cavity resonance suppression effect. I understood it.

  As is apparent from the above description, according to the present invention, it is possible to provide a pneumatic tire that can effectively dissipate heat generated inside the tread portion on the premise of effective reduction of road noise. became.

FIG. 3 is a cross-sectional view in the tire width direction of a tire and rim assembly configured by mounting a typical pneumatic tire according to the present invention on a standard rim, and is grounded under a condition where a maximum load and a pneumatic pressure corresponding to the maximum load are applied. This is indicated by the state. (A) is a development view of the sound absorbing layer of the tire shown in FIG. 1, and (b) is a cross-sectional view of (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tire 2 Tread part 3 Side wall part 4 Bead part 5 Tire main body part 6 Bead core 7 Carcass 8 Belt 9 Tire lumen 10 Inner liner 11 Sound absorption layer 12 Belt end position 13 Thick part 14 Thin part R rim

Claims (7)

In a pneumatic tire in which a band-shaped sound absorbing layer made of a porous material is disposed on the inner surface of the inner liner,
The sound absorbing layer includes a thick part having a relatively large thickness and a thin part having a thickness smaller than the thick part,
The pneumatic tire is characterized in that the thin portion passes through a belt end position.   The pneumatic tire according to claim 1, wherein a thickness of the thin portion is 75% or less of that of the thick portion.   The pneumatic tire according to claim 1 or 2, wherein a length of the thin portion in a tire width direction is 20 mm or more.   The pneumatic tire according to any one of claims 1 to 3, wherein a center position of the thin portion in a tire width direction coincides with a belt end position.   The pneumatic tire according to any one of claims 1 to 4, wherein a length of the thin portion in a tire width direction is the same in a tire circumferential direction.   The pneumatic tire according to claim 1, wherein the thin portion extends continuously in the tire circumferential direction.   The pneumatic tire according to any one of claims 1 to 6, wherein all the thin portions pass through a belt end position.

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