JP2009023548A - 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 radiating one band-like absorbing layer 11 made of a porous material on an internal surface of an inner liner 10. The absorbing layer 11 has at least one notch portion 13 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 single 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. Plan.

  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 or the like 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 single band-shaped sound absorbing layer made of a porous material is disposed on the inner surface of an inner liner, wherein the sound absorbing layer has a belt end position. A pneumatic tire characterized in that it comprises at least one notch passing therethrough. 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 the notch portion of the sound absorbing layer at the belt end position where the internal heat generation is particularly large, the generated heat can be smoothly dissipated from the notch portion into the lumen. The sound absorbing layer preferably extends along the tire circumferential direction, and is particularly preferably disposed over the entire circumference.

  Here, the “notch” of the sound absorbing layer refers to a portion where a porous material does not exist until the inner liner is reached and a through hole is formed. “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.

  Moreover, it is preferable that the notch part changes the tire circumferential direction length along a tire width direction.

  Furthermore, it is preferable that the length in the tire meridian direction measured along the periphery of the tire inner surface between the position where the length in the tire circumferential direction of the notch portion is maximum and the belt end position is 10 mm or less.

  In addition, at the belt end position, it is preferable that the sum of the circumferential lengths of the notches is 15% or more of the circumferential length of the tire inner surface.

  According to this invention, road noise is effectively reduced by the arrangement of the sound absorbing layer, and the heat generated inside the tread portion is effectively reduced in the tire by the notch portion provided at an appropriate position of the sound absorbing layer. It is possible to radiate heat to the cavity.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A 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 FIG. 1 (b) is a developed view of the sound absorbing layer of the tire shown in FIG. 1, showing a ground contact state under a condition where an air pressure corresponding to the maximum load is applied.

  The pneumatic tire 1 according to the present invention includes a tread portion 2 that contacts a road surface, a pair of sidewall portions 3 that extend inward in the tire radial direction from both side portions of the tread portion 2, and tires of the sidewall portions 3. A pair of bead portions 4 provided in the radial direction and fitted to the rim R constitute a tire body portion 5. 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 at a portion corresponding to the tread center region, preferably having a width of 0.1 to 1.0 times the tread width. For fixing the sound absorbing layer 11, for example, heat welding, an adhesive, a double-sided tape, a hook-and-loop fastener, or the like can be used. Further, when the sound absorbing layer is fixed in a raw tire state, vulcanization bonding can also be used.

  The main feature of the configuration of the present invention is that, as shown in FIG. 1 (b), the sound absorbing layer 11 has an extension of a perpendicular drawn from the inner edge of the innermost belt layer to the inner surface of the inner liner 10. The purpose is to provide at least one notch 13 that passes through the end position 12 corresponding to the intersection of the line L and the inner surface of the sound absorbing layer 11.

  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.

  On the other hand, in the tire according to the present invention, the sound absorbing layer 11 is provided with the notch 13, and the heat generated in the tread portion 2 is smoothly radiated to the filling air in the tire lumen 9 through the notch 13. can do. Further, it is known that the heat generation inside the tread portion is particularly large in the vicinity of the belt end position. Therefore, by arranging the notch portion 13 so as to pass through the belt end position 12, a sufficient heat dissipation effect is obtained. Thereby, it is possible to prevent an excessive temperature rise in the tread portion and maintain the durability of the tire.

  When the notch 13 is provided, the development area of the sound absorbing layer 11 is reduced. However, since the end surface of the porous material is exposed at the notch 13, the contact area between the air filled in the tire lumen 9 and the sound absorbing layer 11. Is equivalent to the case where the notch portions 13 are not provided, or rather, when a large number of the notch portions 13 are provided, the contact area increases, so that the sound absorption effect can be maintained at or above the same level.

  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 is composed of one porous material, so that the uniformity can be kept high while being low in cost.

  Moreover, the shape of the notch 13 can be a circle, a polygon, a star, or the like, but it is preferable that the tire circumferential direction length d changes along the tire width direction. With this configuration, it is possible to dispose a relatively large number of notches 13 in a portion where heat generation is particularly large and where heat dissipation is desired, and a relatively small number of notches 13 in other portions. It is possible to achieve both heat dissipation and sound absorption. When the cutout portion 13 is configured in such a shape, the length in the tire meridian direction measured along the peripheral of the tire inner surface between the position where the tire circumferential length d is maximum and the belt end position 12. It is preferable to dispose the sound absorbing layer 11 so that is 10 mm or less. According to this, as described above, since the amount of heat generation in the vicinity of the belt end position 12 is the largest, the position where the notch 13 has the maximum length d in the tire circumferential direction, that is, the position with the highest heat dissipation effect. Is disposed in the vicinity of the position where the heat generation amount is the highest, so that the heat radiation efficiency is increased and the temperature rise of the tread portion can be effectively suppressed.

  Furthermore, at the belt end position 12, the total sum of the circumferential lengths d of the notches 13 is preferably 15% or more of the circumferential length of the tire inner surface. This is because if this ratio is less than 15%, a sufficient heat dissipation effect may not be obtained.

  When the plurality of cutout portions 13 are provided, it is preferable to disperse them in the circumferential direction, and from the viewpoint of maintaining uniformity, it is more preferable that the circumferential arrangement pitch is uniform.

  The area of the notch 13 on the tire inner surface and the number of the cutouts 13 can be appropriately set according to the tire size, use conditions, etc., but the projected area of the sound absorbing layer per tire viewed from the tire center It is preferable that the ratio of the total area of the notch per tire to the inner surface of the tire is greater than 0.01 and less than 0.5. The reason is that when this ratio is 0.01 or less, the heat dissipation effect is small, and when it is 0.5 or more, the cavity resonance reducing effect is small.

  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. .

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

  The tire of the example 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 over the entire inner circumference of the inner liner. Is disposed as a sound absorbing layer, and the circumferential length of the inner surface at the belt end position is 1850 mm. The sound-absorbing layer is provided with 60 notches at a total of 30 locations on each width end. This notch has a so-called diamond shape as shown in FIG. 1B, the tire width direction length is 20 mm, the tire circumferential direction length is 15 mm, and the tire circumferential direction length is maximum. The position matches the midpoint of the tire width direction length and the belt end position.

  For comparison, the tire of Conventional Example 1 having the same configuration as the tire of the example except that it does not have a sound absorbing layer, except that the sound absorbing layer is not provided with a notch. The tire of Conventional Example 2 having the same configuration as the tire of No. 1 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 the conventional example 2 in which the sound absorbing layer is provided is set to 100 with respect to the sound pressure level of the 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. 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 example tire has a significantly improved cavity resonance suppression effect while maintaining the durability at the same level as that of the tire of the conventional example 1. In comparison, it can be seen that the durability is greatly improved while maintaining the cavity resonance suppression effect at the same level.

  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.

(A) is sectional drawing in the tire width direction of the tire and rim assembly comprised by mounting the typical pneumatic tire according to this invention on the standard rim, and applies the air pressure corresponding to the maximum load and the maximum load. (B) is a development view of the sound absorbing layer of the tire shown in (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 Notch part R rim

Claims (4)

In a pneumatic tire in which a single band-shaped sound absorbing layer made of a porous material is disposed on the inner surface of an inner liner,
The pneumatic tire is characterized in that the sound absorbing layer includes at least one notch passing through a belt end position.   The pneumatic tire according to claim 1, wherein the notch portion has a tire circumferential direction length that varies along a tire width direction.   The tire meridian direction length measured along the peripheral of the tire inner surface between a position where the tire circumferential direction length of the notch portion is maximum and a belt end position is 10 mm or less. The described pneumatic tire.   The pneumatic tire according to any one of claims 1 to 3, wherein the sum of the circumferential lengths of the notches is 15% or more of the circumferential length of the tire inner surface at a belt end position.

Images