JP2009137568A - Tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tire effectively suppressing cavity resonance, and reducing a road noise. <P>SOLUTION: The tire is provided with a sound absorption layer on the inner surface of an inner liner. The sound absorption layer is made from non-woven fabric formed by joining fibers to each other. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a tire provided with a sound absorbing layer on the inner surface of an inner liner, and particularly intends to effectively suppress cavity resonance of the tire and reduce road noise.

  In a tire assembled on a rim and attached to a vehicle, the tread portion oscillates against the road surface unevenness while the vehicle is running, so that the air filled in the tire cavity resonates. 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 the road noise is transmitted to the vehicle interior, unlike a noise in other frequency bands, it takes a sharp and high peak value, which is annoying noise for passengers in the vehicle interior.

  In order to suppress such cavity resonance and reduce road noise, Patent Document 1 discloses an annular sound absorbing layer for noise control made of nonwoven fabric in a tire lumen formed by a rim and a tire attached to the rim. Tires fixed in the circumferential direction have been proposed.

Japanese Patent No. 3622957

  However, in the tire described in Patent Document 1, a centrifugal force is applied to the sound absorbing layer during rolling of the tire load, the sound absorbing layer is excessively compressed and deformed, and the density of the sound absorbing layer becomes too large. There is a possibility that road noise due to cavity resonance cannot be effectively reduced without sufficiently obtaining the effect.

  Therefore, an object of the present invention is to solve these problems, and an object of the present invention is to provide a tire in which road resonance is reduced by effectively suppressing cavity resonance of the tire.

  In order to achieve the above object, the tire according to the present invention includes a sound absorbing layer on the inner surface of the inner liner, and the sound absorbing layer is composed of a nonwoven fabric formed by bonding between fibers. In the tire having such a configuration, road noise due to cavity resonance is reduced by disposing a sound absorbing layer made of nonwoven fabric. In addition, since the fibers constituting the nonwoven fabric are bonded, compared to the case where the fibers are not bonded, the nonwoven fabric is deformed by aging, temperature change, external force change, especially centrifugal force applied during tire rotation. Therefore, the thickness of the nonwoven fabric can be maintained, and it is possible to secure a sufficient distance for the sound wave to pass through the nonwoven fabric. As a result, it is possible to effectively secure the sound absorption effect and reduce road noise. Furthermore, it becomes possible to suppress the dropout of the fibers constituting the nonwoven fabric when the tire is loaded.

  Further, the fibers are preferably bonded by heat welding. Alternatively, the fibers are preferably bonded by an adhesive.

  Furthermore, the adhesive is preferably selected from the group consisting of a thermosetting resin, a plastic resin, an elastomer resin, and a composite resin.

  Furthermore, the fiber is selected from the group consisting of aromatic polyamide, aromatic polyimide, polybenzimidazole, polyphenylene sulfide, polyvinyl alcohol, polyethylene terephthalate, polyethylene naphthalate, carbon fiber, fluorine fiber, glass fiber, and metal fiber. It is preferable.

  In addition, the adhesive is preferably a resin selected from the group consisting of an epoxy resin system or a polyimide resin system.

  In addition, the weight of the adhesive is preferably in the range of 20 to 50% of the weight of the nonwoven fabric.

Moreover, it is preferable that the density of a nonwoven fabric exists in the range of 5-20 kg / m < ³ >, and the thickness exists in the range of 5-20 mm. As used herein, “thickness” refers to the average thickness of the nonwoven fabric.

  Furthermore, the sound absorbing layer preferably has compression resistance in the layer thickness direction.

Furthermore, it is preferable that the thickness of the nonwoven fabric when the centrifugal force is applied by the rotational motion with the centripetal acceleration of 900 m / s ² is not less than 0.6 times the thickness of the nonwoven fabric when the centrifugal force is not applied. Or 0.8 times or more, more preferably 0.9 times or more.

  According to the present invention, it is possible to provide a tire that effectively suppresses cavity resonance and reduces road noise by optimizing the sound absorbing layer.

  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 an assembly of a tire and a rim R formed by mounting a representative tire according to the present invention on the rim R. 2 is a cross-sectional view of the tire shown in FIG. 1 in the tire circumferential direction.

  A tire 1 according to the present invention includes a tread portion 2 that contacts a road surface, a pair of sidewall portions 3 and 3 that extend inward in the tire radial direction from both side portions of the tread portion 2, and each sidewall portion 3, 3, according to common practice. The tire body 5 is composed of a pair of bead portions 4 and 4 that are provided on the inner side in the tire radial direction and fitted to the rim R. Inside the tire main body 5, a carcass 7 having a radial structure, for example, which extends in a toroidal shape between the bead cores 6 and 6 embedded in the bead parts 4 and 4 and forms the skeleton structure of the tire main body 5, and the carcass 7 is disposed on the outer peripheral side of the crown region, and a belt 8 that reinforces the tread portion 2 is disposed. 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 non-woven fabric formed by bonding fibers is disposed over the entire circumference, whereby a cavity generated in the tire lumen 9. The vibration energy of the filling air accompanying the resonance is converted into the internal vibration energy of the nonwoven fabric constituting the sound absorbing layer 11 and is consumed as heat energy, thereby reducing the cavity resonance sound. Each of the fibers 12 constituting the nonwoven fabric has a region around each fiber where each of the fibers effectively exhibits sound absorption. The larger the region, the greater the sound absorption effect. However, if the density of the non-woven fabric becomes too high, the arrangement of the fibers becomes too dense and the areas that exhibit the sound absorbing effect overlap each other, so that such areas become smaller and the sound absorbing effect is also reduced. Since the tire 1 having such a configuration is bonded between the fibers constituting the nonwoven fabric, the compression rigidity in the thickness direction of the nonwoven fabric is improved as compared with the case where the nonwoven fabric is not bonded between the fibers, Even if the nonwoven fabric deteriorates and changes over time, even if the nonwoven fabric is made of a material that is easily affected by temperature and changes in temperature, or when the tire 1 rotates, centrifugal force is applied to the nonwoven fabric. Even if the external force is changed due to, for example, the nonwoven fabric is not excessively deformed, the distance between fibers constituting the nonwoven fabric does not become too small. For these reasons, it is possible to sufficiently secure the volume of the region where the sound absorption effect described above is ensured and to suppress the generation of road noise without reducing the sound absorption effect. Furthermore, since the fibers are bonded to each other, each fiber 12 is less likely to come off than a non-woven fabric that is not bonded to each other. Dropping can be suppressed. The non-woven fabric is obtained by intertwining organic fibers such as polyethylene terephthalate (PET), rayon or aramid, inorganic fibers such as glass or carbon, animal-derived fibers, plant-derived fibers, and the like. Specifically, the fiber is selected from the group consisting of aromatic polyamide, aromatic polyimide, polybenzimidazole, polyphenylene sulfide, polyvinyl alcohol, polyethylene terephthalate, polyethylene naphthalate, carbon fiber, fluorine fiber, glass fiber, and metal fiber. Is preferred. Further, the length of the fiber can be arbitrarily set.

Moreover, as shown in FIG. 3, it is preferable that the fibers are bonded by heat welding. Alternatively, as shown in FIG. 4, the fibers are preferably bonded by applying an adhesive 13. Examples of the method for thermally bonding the fibers include a thermal bonding method in which knitted fibers are melted by heat to bond the fibers. Specifically, the thermal bonding method is a method in which the entire fiber is made of a thermoplastic resin, and the fiber itself is heated and melted to directly bond the contacted portions between the fibers, or the melting point is lower than that of the fiber. There is a method of indirectly bonding fibers by melting a thermoplastic resin and applying between the fibers. In the chemical bonding method in which fibers are bonded by applying an adhesive, the adhesive is a group consisting of a thermosetting resin, a plastic resin, an elastomer resin, and a composite resin from the viewpoint of adhesion between fibers. It is preferable to use it as a more selected adhesive. At this time, the weight of the adhesive is preferably in the range of 20 to 50% of the weight of the nonwoven fabric. This is because when the weight of the adhesive is less than 20% of the weight of the nonwoven fabric, the bonding between the fibers becomes insufficient, and the fibers fall off from the nonwoven fabric or the nonwoven fabric peels off from the tire inner surface. Because there is a possibility. On the other hand, when the weight of the adhesive exceeds 50% of the weight of the nonwoven fabric, ensuring the amount of fiber that exhibits a sufficient sound absorbing effect, the weight of the nonwoven fabric becomes too large, the tire uniformity deteriorates, and This is because the fuel consumption may be reduced. Further, the inventor generates heat during high-speed running, and further, centrifugal force is applied to the nonwoven fabric due to rotation of the tire, so if the fibers are bonded with an adhesive that easily softens due to heat, It has been found that there is a possibility that the non-woven fabric is compressed and deformed and the sound absorbing effect cannot be obtained sufficiently. As a countermeasure, the adhesive is preferably a resin selected from the group consisting of an epoxy resin system or a polyimide resin system. This is because the adhesive is made of a resin selected from the group consisting of an epoxy resin system or a polyimide resin system having a thermosetting property, so that even if the tire generates heat during high-speed driving, deformation of the nonwoven fabric is suppressed, and sound absorption is achieved. This is because the effect can be effectively secured.
In addition to the above-mentioned bonding method, it is also possible to combine the above-mentioned bonding method with a needle punch method in which a staple is inserted into a nonwoven fabric and mechanically bonded to the fiber, or a spunlace method in which fibers are entangled using high-pressure water flow. It is. Moreover, it is preferable that the density of a nonwoven fabric exists in the range of 5-20 kg / m < ³ >, and the thickness exists in the range of 5-20 mm. Because, if the density and thickness of the nonwoven fabric are out of both ranges, the sound absorption effect is not sufficiently ensured, and the silence due to the nonwoven fabric is not effectively improved, or the nonwoven fabric This is because, although the noise reduction due to the arrangement of the tires is effectively improved, the tire weight becomes too large, the tire uniformity may deteriorate, and the fuel efficiency may decrease.

  Furthermore, the sound absorbing layer 11 preferably has compression resistance in the layer thickness direction, that is, shape stability in the thickness direction of the nonwoven fabric sound absorbing material during running. Since the sound-absorbing layer 11 has compression resistance in the layer thickness direction, the non-compression resistance changes with time, temperature change, external force change, especially changes due to the centrifugal force applied during tire rotation, compared to the case without compression resistance. It can suppress effectively, can maintain the thickness of a nonwoven fabric, and can fully ensure the distance which a sound wave passes in a nonwoven fabric. Therefore, it is possible to effectively secure a sound absorption effect and reduce road noise.

Furthermore, it is preferable that the thickness of the nonwoven fabric when the centrifugal force is applied by the rotational motion with a centripetal acceleration of 900 m / s ² is not less than 0.6 times the thickness of the nonwoven fabric when the centrifugal force is not applied. Or 0.8 times or more, more preferably 0.9 times or more. Generally, the centripetal acceleration in the tire at a riding speed of 60 km / hr is 900 m / s ² . For this reason, when the thickness of the nonwoven fabric is specified, the thickness of the nonwoven fabric when a centrifugal force is applied due to a rotational motion with a centripetal acceleration of 900 m / s ² is important. If the thickness of the nonwoven fabric is not less than 0.6 times the thickness of the nonwoven fabric when no centrifugal force is applied when the centrifugal force is applied to the nonwoven fabric, the nonwoven fabric is sufficiently suppressed from being compressed and deformed. Since the distance between the fibers that constitute the material does not become too small, it is possible to secure a sufficient area for the sound absorption effect as described above. The centripetal acceleration is calculated as a value obtained by multiplying the rotation radius r by the square of the rotation angular velocity ω, that is, rω ² when the rotation radius r and the rotation angular velocity ω are set.

  When attaching a sound absorbing layer to the tire body, use a styrene-butadiene rubber latex adhesive, an aqueous polymer-isocyanate adhesive, or an acrylic or synthetic resin adhesive tape on the inner surface of the inner liner. It can also be chemically bonded, and when a sound absorbing layer is affixed to an unvulcanized tire body, it is temporarily fixed with such an adhesive tape or adhesive, and then vulcanized and molded by heating and pressurizing. The layer can also be physically fixed by impregnating the inner surface of the inner liner.

  The above description shows only a part of the embodiment of the present invention, and these configurations can be combined alternately or various changes can be made without departing from the gist of the present invention. For example, although not shown, the sound absorbing layer can be attached to the inner surface of the sidewall portion. Moreover, although a sound absorption layer can also be affixed over a periphery on a tire inner surface, it is also possible to affix it partially on a tire inner surface.

  Next, according to the present invention, a tire of a comparative example (comparative tires 1 to 4) having a sound absorbing layer constituted by a nonwoven fabric in which fibers are not bonded is provided on the inner surface of the tread portion, and a nonwoven fabric in which fibers are bonded. The tires (Example tires 1 to 3) each having a sound absorbing layer were prototyped and subjected to various evaluations as radial tires for passenger cars having a tire size of 215 / 45R17, and will be described below.

  The comparative tires 1 and 2 have a sound absorbing layer constituted by a nonwoven fabric in which fibers are not bonded on the inner surface of the tread portion, and the comparative tire 3 has a sound absorbing layer constituted by a sponge on the inner surface of the tread portion. Each has the specifications shown in Table 1. The example tire 1 includes a sound absorbing layer composed of a nonwoven fabric in which fibers are bonded by applying an adhesive by a chemical bonding method, and has the specifications shown in Table 1, respectively. In addition, the sound absorption layer is affixed on the inner surface of the tread portion with a double-sided adhesive tape made of acrylic adhesive (5000N manufactured by NITTO DENKO) over the entire circumference.

  Each of these test tires is attached to a rim having a size of 17 × 7 JJ to form a tire wheel. The tire wheel is mounted on a vehicle, and the air pressure: 210 kPa (relative pressure) and the tire load load: 3.92 kN are applied. It used for performance evaluation.

In order to suppress the cavity resonance, the room noise was measured when the vehicle traveled on an asphalt road surface at a speed of 60 km / h. The centripetal acceleration is about 900 m / s ² from the rotation radius r and the rotation angular velocity ω. 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 2. In addition, the evaluation result in a table | surface is indexed by making the reduction amount of the sound pressure level in the comparative example tire 1 with respect to the sound pressure level of the tire which does not provide a nonwoven fabric into 100, and calculated the numerical value in another tire. At this time, the larger the value, the greater the effect of suppressing cavity resonance.

  Moreover, the fiber drop-off was evaluated by visual observation as to whether or not a part of the fibers constituting the non-woven fabric was dropped after running for evaluating the cavity resonance suppression effect. The evaluation results are shown in Table 2.

Moreover, the nonwoven fabric thickness after high-speed driving | running was evaluated by measuring the change of nonwoven fabric thickness, after making the vehicle mentioned above drive | work 600 km at the speed of 300 km / h. The nonwoven fabric thickness is calculated as a percentage of the thickness T ₁ after traveling with respect to the thickness T ₀ before traveling, and is indexed with the reduction amount of the thickness in the comparative tire 3 as 100. Numerical values were calculated, and the evaluation results are shown in Table 2. In addition, the smaller the numerical value of the evaluation result in the table, the smaller the compression deformation and the smaller the thickness.

  As is clear from the results in Table 2, the comparative example tire 3 does not effectively improve the cavity resonance suppression effect, whereas the comparative tires 1 and 2 and the example tires 1 to 3 have the cavity resonance suppression effect. Had improved. At this time, in the comparative tires 1 and 2, the fibers constituting the nonwoven fabric had dropped out, whereas in the tires 1 to 3, the fibers did not drop out. Moreover, compared with Example tires 1-3, Comparative Example tires 1-3 had deteriorated thickness retention after high-speed running. From these things, it is clear that Example tires 1-3 are excellent also in any performance mentioned above.

  As is apparent from the above, the present invention makes it possible to provide a tire that effectively suppresses cavity resonance in the tire and reduces road noise by optimizing the sound absorbing layer.

1 is a sectional view in the tire width direction of a typical tire according to the present invention assembled with a rim. FIG. It is a tire circumferential direction sectional view of the tire shown in FIG. It is an image figure of the nonwoven fabric which couple | bonded between fibers by heat welding. It is an image figure of the nonwoven fabric which couple | bonded the fibers with the adhesive agent.

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 Fiber 13 Adhesive R Rim

Claims (10)

In a tire having a sound absorbing layer on the inner surface of the inner liner,
The tire is characterized in that the sound absorbing layer is composed of a nonwoven fabric formed by bonding fibers.   The tire according to claim 1, wherein the fibers are bonded by heat welding.   The tire according to claim 1, wherein the fibers are bonded by an adhesive.   The tire according to claim 3, wherein the adhesive is selected from the group consisting of a thermosetting resin, a plastic resin, an elastomer resin, and a composite resin.   The fiber is selected from the group consisting of aromatic polyamide, aromatic polyimide, polybenzimidazole, polyphenylene sulfide, polyvinyl alcohol, polyethylene terephthalate, polyethylene naphthalate, carbon fiber, fluorine fiber, glass fiber, and metal fiber. Item 5. The tire according to any one of Items 1 to 4.   The tire according to any one of claims 3 to 5, wherein the adhesive is a resin selected from the group consisting of an epoxy resin system or a polyimide resin system.   The tire according to any one of claims 3 to 6, wherein a weight of the adhesive is in a range of 20 to 50% of a weight of the nonwoven fabric. Density of the nonwoven fabric is in the range of 5 to 20 kg / ^{m 3,} the thickness of the nonwoven fabric is in the range of 5 to 20 mm, the tire according to any one of claims 1 to 7.   The tire according to any one of claims 1 to 8, wherein the sound absorbing layer has compression resistance in a layer thickness direction. The thickness of the said nonwoven fabric at the time of centrifugal force load by the rotational motion of centripetal acceleration 900m / s < ² > is 0.6 times or more of the thickness of this nonwoven fabric at the time of centrifugal force no load. The tire according to claim 1.

Images