JP2008174080A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire effectively decreasing road noise, and effectively radiating the inside heat quantity of a tread portion. <P>SOLUTION: On an inner periphery side of the tread portion 3 of a tire body 2, a band-shaped foam element 5 is extended in a circumferential direction and adhered on an inner liner 4. The foam element 5 is provided with one or more through holes 13 reaching the inner liner 4. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a pneumatic tire that reduces vehicle interior noise, and more particularly, vibration of filled air in a tire chamber defined by a pneumatic tire and an application rim in which the pneumatic tire is airtightly assembled. A technique for reducing the cavity resonance generated by the above is proposed.

  The rim-assembled pneumatic tire has an internal shape, etc. due to the fact that the tire tread part vibrates against the road surface unevenness while the vehicle is running, causing the filled air in the tire to vibrate. The resulting cavity resonance results in noise called road noise in the car cabin.

  The resonance frequency of such cavity resonance is mostly in the range of 180 to 300 Hz for passenger car pneumatic tires. When the resonance sound is transmitted into the vehicle interior, noise in other frequency bands is present. In contrast, since the peak value is sharp and high, the road noise becomes annoying noise for passengers in the vehicle interior.

Therefore, in Patent Document 1, a sponge material is used in the tire lumen formed by the rim and the pneumatic tire bonded to the rim in order to enhance the suppression effect of the cavity resonance and greatly reduce road noise. A non-ring-shaped band-shaped sheet for noise suppression is fixed in the tire circumferential direction, and the band-shaped sheet has a volume S2 in which the ratio S2 / S1 to the total volume S1 of the tire lumen is 0.4% or more. In addition, the sponge material has a surface having a specific gravity of 0.005 to 0.06 and facing the tire lumen of the belt-like sheet as an uneven surface, and the uneven surface has a projecting convex portion and a hollow shape. There is proposed an assembly of a pneumatic tire and a rim, characterized in that the concave portions of the tire are scattered in the tire circumferential direction or the tire axial direction without being evenly arranged and the concave and convex portions are repeated.
Japanese Patent No. 3622957

  By the way, according to this proposed technique, road noise during running of the vehicle can be effectively reduced under the action of a strip-like sheet using a sponge material. However, in the proposed technique, a so-called sponge in which rubber or synthetic resin is foamed is used. Since the belt-like sheet made of, for example, is fixed to the inner liner on the inner circumference side of the tread portion by extending in the circumferential direction, heat generation inside the tread portion is caused by the presence of the belt-like sheet having a heat insulating function. There has been a disadvantage that heat cannot be smoothly dissipated into the lumen defined by the pneumatic tire and the rim.

  That is, the tread portion generates heat internally due to friction with the road surface of the tread contact surface, elastic deformation of the tread rubber, etc., and the belt-like sheet fixed to the inner liner diverges the heat generated into the tire lumen. As a result, the carcass cord, belt cord, etc. 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. This is particularly serious when the tire rolls on a high-temperature road surface or when the tire rolls at high speed.

  An object of the present invention is to solve such problems of the prior art, and the main purpose of the invention is to achieve effective reduction of road noise while still effectively reducing the internal heat quantity of the tread portion. In addition to the above, another object of the present invention is to provide a pneumatic tire that can correct the imbalance in the weight balance in the circumferential direction of the tire body. To provide.

  The pneumatic tire according to the present invention is an inner peripheral side of the tread portion of the tire body, and in many cases, a belt-like foam is applied to the inner liner at a portion corresponding to the tread center region, and the posture in the circumferential direction is extended. Thus, for example, one or more through holes reaching the inner liner, which are continuously fixed over the entire circumference of the foam or evenly fixed at a plurality of predetermined intervals. For example, a through hole is provided in which the cross-sectional contour shape can be a circular shape, a polygonal shape, or the like, or a different shape such as a star shape.

  Here, as long as the through-hole reaches the inner liner, the through-hole can be inclined in the width direction or the circumferential direction of the tread portion in addition to the one extending in the radial direction of the tire. .

  The “foam” herein can be composed of a literal foam material having open cells or closed cells formed by foaming rubber or synthetic resin, and also involves animal fibers, plant fibers, synthetic fibers, etc. It can also be composed of a woven fabric, a nonwoven fabric, a knitted fabric or the like integrated together.

  In such a pneumatic tire, the through-holes are preferably provided in a distributed manner in the circumferential direction, and the dispersion form at this time is preferably a dispersive arrangement with regularity.

  And preferably, regardless of whether or not the through holes are distributed in the circumferential direction, the formation density of the through holes in the foam portion located corresponding to the portion having a large weight in the circumferential direction of the tire body Is made larger than that of the other corresponding parts to reduce or absorb the large weight.

にあることが好ましい。
これはすなわち、０．０１以下だと放熱効果が少なく、０．５以上だと、空洞共鳴低減効果が少なくなることによるものである。 Here, “the formation density of the through holes” refers to the ratio of the total area of the through holes on the inner liner surface to the unit projected area of the foam viewed from the center of the tire.
When considering per tire,

It is preferable that it exists in.
This is because the heat dissipation effect is small when it is 0.01 or less, and the cavity resonance reduction effect is reduced when it is 0.5 or more.

  In this case, when there are a plurality of locations where the weight of the tire body is large on the circumference, the formation density of through holes should be increased at each of those locations, and the size of the weight at the plurality of locations should be When there is a difference, the formation density is changed according to the size.

  By the way, the foam is preferably composed of an ether-based polyurethane foam or a synthetic rubber foam material.

  In the pneumatic tire according to the present invention, when the tire is assembled to the rim and filled with air pressure to cause load rolling, the tire is subjected to the occurrence of cavity resonance under the action of the foam fixed to the inner liner. By converting most of the vibration energy of the filled air in the air chamber into the internal vibration energy of the foam and consuming it as thermal energy, the cavity resonance noise can be effectively reduced.

  In addition, in this tire, the internal heat quantity of the tread portion that generates heat due to the load rolling of the tire is smoothly transferred into the tire chamber of the rim-assembled tire through the through hole of the required cross-sectional area that is provided in the foam and reaches the inner liner. In addition, since the heat can be dissipated sufficiently, the possibility of peeling from the rubber of various cords due to the accumulated heat generated inside the tread is advantageously removed, resulting in a decrease in tire durability. Can be effectively prevented.

  In addition, the foam through-hole also increases the contact area between the filled air into the tire and the foam, so that the vibration energy of the filled air can also function to increase the consumption by the foam. As a result, the cavity resonance noise is further reduced. This is more effective when the cross-sectional contour shape of the through hole is an irregular shape such as a star, and the hole wall surface area is increased as much as possible in relation to a predetermined hole cross-sectional area.

  Thus, in the pneumatic tire according to the present invention, under the action of the through hole provided in the foam, heat storage inside the tread portion is effectively prevented, and the possibility of a decrease in the durability of the tire is advantageously removed. The cavity resonance can be effectively reduced by the original function of the foam.

  In the tire as described above, when the through-holes are distributed in the circumferential direction, the heat dissipation amount of the heat generated inside the tread portion is further increased to the tire air to further improve the durability of the tire. Can do. In this case, when the through holes are dispersedly arranged with regularity, heat radiation into the tire chamber in the circumferential direction can be made sufficiently uniform, and more uniform cooling of the entire tread portion can be realized. At the same time, the tire unbalance can be reduced and the occurrence of vibration during tire rotation can be advantageously suppressed. From this point, too, the load rolling of the tire on a hot road surface and the high speed The durability against load rolling and the like can be further improved in combination with the heat dissipation effect.

  In addition, by increasing the formation density of the through holes in the foam portion located corresponding to the portion having a large weight in the circumferential direction of the tire body, each of the through holes is combined with the heat dissipation function, By exerting the weight offset function, the tire can be unbalanced in the circumferential direction and the uniformity can be improved. Further, durability against high-speed rotation or the like can be further effectively improved.

  By the way, when the foam is formed into an ether-based polyurethane foam, it can bring an advantage that the foam is hardly hydrolyzed. When the foam is formed of a synthetic rubber foam material, Excellent heat resistance and water resistance can be imparted.

  FIG. 1 is a cross-sectional view in the width direction showing an embodiment of a pneumatic tire according to the present invention in a tire posture in which a rim is assembled to an applicable rim and filled with a prescribed air pressure.

Here, “applicable rim” means a rim defined in the following standards according to the tire size, and “specified air pressure” means an air pressure defined in accordance with the maximum load capacity in the following standards. The maximum load capacity refers to the maximum mass allowed to be loaded on the tire according to the following standards.
The air here can be replaced with an inert gas such as nitrogen gas or the like.

  The standard is an industrial standard that is valid in the region where tires are produced or used. For example, “THE TIRE AND RIM ASSOCIATION INC. YEAR BOOK” in the United States, and “THE European Tire and Rim Technical” in Europe. “STANDARDS MANUAL” of Organization, and “JATMA YEAR BOOK” of Japan Automobile Tire Association in Japan.

In the figure, reference numeral 1 denotes a pneumatic tire. The pneumatic tire 1 has a belt-like foam 5 extending in the circumferential direction on the inner liner 4 on the inner peripheral side of the dread portion 3 of the tire body 2. For example, the tire body 2 is fixed over the entire circumference thereof, and the tire body 2 is here a pair of sidewall portions 7 extending inward in the radial direction from each side portion of the tread portion 3 on which the tread ground contact surface 6 is formed. And a bead portion 8 provided continuously on the inner peripheral side of each sidewall portion 7 and extending toroidal between the bead cores 9 disposed in each bead portion 8 to form a skeleton structure of the tire body 2, for example, A carcass 10 having a radial structure and a belt 11 that is disposed on the outer peripheral side of the crown region of the carcass 10 and reinforces the tread portion 2 are provided.
In the figure, reference numeral 12 denotes a rim assembled to the pneumatic tire 1.

  Here, as described above, the foam 5 is integrated by intertwining animal fibers, plant fibers, synthetic fibers, etc., in addition to the foamed material having open cells or closed cells formed by foaming rubber or synthetic resin. The foam 5 can be composed of a woven fabric, a non-woven fabric, a knitted fabric or the like, and the foamed body 5 is mostly a portion corresponding to the tread center region, preferably a synthetic rubber or other adhesive, The inner liner 4 can be fixed with a width of 0.1 to 1 times the width W.

  And here, the foam 5 fixed to the inner liner 4, for example, the entire circumference thereof, penetrates to the foam as shown in FIG. At least one through hole 13 reaching the inner liner, in the figure, is provided.

  Here, the extending direction of the through-hole 13 can be the radial direction of the tire 1 as shown in FIGS. 1 and 2, and the direction inclined in the width direction or the circumferential direction of the tread portion 3. In the latter case, there is an advantage that the contact area of the air filled in the tire chamber with the wall surface of the through hole can be increased.

  In addition, here, the cross-sectional shape of the through hole 13 perpendicular to the center line is a circular shape, a polygonal shape, etc., as well as a star shape and other irregular shapes in relation to the required heat dissipation function. Also in this case, in order to increase the contact area of the wall surface of the through hole with the air filled in the tire chamber, the cross-sectional ring shape of the through hole should be a star or other irregular shape. Is preferred.

  In addition, when a plurality of through holes 13 are provided in the foam 5, if the foam 5 is disposed continuously in the circumferential direction, it is different from being intermittently disposed in the circumferential direction. It is preferable that the through holes 13 are regularly arranged in order to uniformly dissipate the heat quantity in the tread portion into the tire chamber over the entire circumference. Also, the tire body 2, and thus the pneumatic tire 1. This is suitable for maintaining the weight balance in the circumferential direction.

  On the other hand, when the tire body itself has a portion having a large weight and a portion having a small weight in the circumferential direction, the tire body itself penetrates into the foam portion located corresponding to the portion having a large weight in the circumferential direction. The formation density of the holes 13 is made larger than that of other corresponding parts as shown in FIG. 2, for example, as illustrated in FIG. 3, and weight imbalance is absorbed by the through holes 13. As a result, the weight balance in the circumferential direction of the entire pneumatic tire is made sufficiently uniform, thereby enabling the entire tread portion to be more evenly cooled and the high-speed load rotation of the pneumatic tire 1. It is possible to exhibit better durability against movement.

  By the way, in this case, when there are a plurality of portions having a large weight on the circumference, it is preferable to increase the formation density of the through holes 13 in any of those portions, and there is a difference in the size of the weight. In some cases, it is preferable to change the size of the formation density of the through holes 13 according to the degree of weight.

  In the pneumatic tire as described above, when the foam 5 is made of an ether-based polyurethane foam, the foam 5 can be provided with excellent hydrolysis resistance, and the foam When 5 is comprised with the synthetic rubber foam, high heat resistance, water resistance, etc. can be provided to the foam 5.

  The foam is composed of an ether-based polyurethane foam, has a structure as shown in a cross-sectional view in the width direction in FIG. 1, and has four circumferential main grooves extending in the tire circumferential direction on the tread surface. Example 245/45 R19 Example A pneumatic tire was manufactured, and the tire was assembled to a rim of 7.5 JJ × 19a, and the air pressure of 230 kPa was filled into the tire chamber.

  In this tire, the cross-sectional width of the foam is set to 100 mm, the thickness is set to 20 mm, and the foam is continuously arranged over the entire circumference. In Example Tire 1, a plurality of through holes are formed in the foam in FIG. As shown in FIG. 3, the tire 2 is regularly formed over the entire circumference as shown in FIG. 3, and the tire 2 of the example is concentrated at the location corresponding to the circumferential location where the weight of the tire body is large, as shown in FIG. 3. 6 through holes are formed, but no through holes are formed in other portions.

The comparative example tire 1 was the same as the example tire except that the foam was not disposed, and the comparative example tire 2 was obtained by omitting the through hole from the example tire 1.
And the comparative example tire 3 shall replace each through-hole of the Example tire 1 with the hollow whose depth is 10 mm.

  When each of these tires was measured for road noise reduction effect and high-speed durability, the results shown in FIG. 4 and Table 1 were obtained.

Here, the road noise reduction effect is evaluated by measuring the peak value of the vehicle interior noise around 200 Hz when the tire is mounted on an actual vehicle and traveling on an asphalt road surface at 60 km / h.
The high-speed durability was evaluated by performing a high-speed durability test in which a tire loaded with a mass corresponding to the maximum load capacity was rotated on a drum and a rotation speed until the tire was broken was measured.

This high-speed durability was evaluated as an index using the comparative tire 1 as a control, and the higher the index value, the better the result.
Table 1 also shows the static unbalance amount of the tire.

  According to the graph shown in FIG. 4, the comparative tires 2 and 3 provided with the foam can greatly reduce the cavity resonance noise as compared with the comparative tire 1. It can be seen that both 2 can reduce the cavity resonance noise to the same extent as the comparative tires 2 and 3.

  Moreover, according to the place shown in Table 1, compared with the comparative example tire 1, the comparative example tires 2 and 3 which do not have a through-hole in a foam will reduce high-speed durability 20%, It can be seen that the example tire 1 can exhibit high-speed durability equivalent to that of the comparative example tire 1, and the example tire 2 can improve the durability more than the comparative example tires 2 and 3.

1 is a cross-sectional view in the width direction showing an embodiment of the present invention in a tire posture assembled to an applicable rim and filled with a prescribed air pressure. It is the principal part plane expanded view and sectional drawing which show the example of formation of the several through-hole to a foam. FIG. 3 is a view similar to FIG. 2 showing an example of increasing the formation density of through holes. It is a graph which shows the comparison result of the peak level of cavity resonance noise.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tire main body 3 Tread part 4 Inner liner 5 Foam 6 Tread ground surface 7 Side wall part 8 Bead part 9 Bead core 10 Carcass 11 Belt 12 Rim 13 Through-hole W Tread ground surface width

Claims (6)

A pneumatic tire formed by extending a belt-like foam in the circumferential direction and adhering to the inner liner on the inner peripheral side of the tread portion of the tire body,
A pneumatic tire in which one or more through holes reaching the inner liner are provided in the foam.   The pneumatic tire according to claim 1, wherein the through holes are provided by being distributed in the circumferential direction.   The pneumatic tire according to claim 2, wherein the through holes are provided with regularity in the circumferential direction.   The pneumatic according to claim 1 or 2, wherein the shape density of the through holes to the foam portion located corresponding to the portion having a large weight in the circumferential direction of the tire body is larger than that of the other corresponding portion. tire.   The pneumatic tire according to any one of claims 1 to 4, wherein the foam is made of an ether-based polyurethane foam.   The pneumatic tire according to any one of claims 1 to 4, wherein the foam is made of a synthetic rubber foam material.

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