JP2008265430A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire improved in high-speed performance, especially in high-speed durability and high-seed traveling stability. <P>SOLUTION: A belt end rubber 11 has: an inside belt end rubber 11A disposed between a carcass layer 5 and an inside belt layer 9A; a middle belt end rubber 11B disposed between the inside belt layer 9A and an outside belt layer 9B; and an outside belt end rubber 11C disposed between an outside belt layer 9B and a tread portion 15 (a belt protecting layer 13). The inside belt end rubber 11A, the middle belt end rubber 11B, and the outside belt end rubber 11C are formed from rubber material constituting the belt layer and rubber material having a loss tangent (tanδ) smaller than the rubber material. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire including a belt end rubber at a tread width direction end portion of a belt layer (an inner belt layer and an outer belt layer).

  Conventionally, various pneumatic tires that improve high-speed performance such as high-speed durability and high-speed running stability by suppressing the tread portion from being pushed outward in the tire radial direction by centrifugal force when traveling at high speed. Proposals have been made.

For example, a pneumatic tire in which a belt protective layer in which a cord wound spirally in the tire circumferential direction is covered with a rubber material is disposed on the outer side in the tire radial direction of the belt layer (see, for example, Patent Document 1), a carcass layer and a belt A pneumatic tire in which a rubber layer is disposed between the layers (see, for example, Patent Document 2), and a pneumatic tire in which a rubber layer is disposed between a belt layer and a belt protective layer (see, for example, Patent Document 3) ) Is disclosed.
JP-T-2003-511299 (2nd page-3rd page, Fig. 1-3) JP-A-1-226405 (first page-second page, Fig. 2) JP-A-2-28003 (first page-second page, FIG. 1-FIG. 3)

  By the way, the deformation due to the protrusion of the tread portion not only deteriorates the high-speed durability represented by the damage to the skeleton member (for example, the carcass layer and the belt layer) that occurs when the deformation amount becomes large, but also the tire. As the distortion increases, heat is generated and the rolling resistance is deteriorated, and various performances such as different maneuverability at low speed and high speed are affected.

  Many pneumatic tires use nylon cords for the belt protective layer, but when higher speed performance is required, hybrid cords in which nylon cord and aramid cord are twisted together are used for the belt protective layer. Yes. By using this hybrid cord for the belt protective layer, it is possible to suppress the deformation due to the tread portion protruding more than when only the nylon cord is used, and it is possible to further improve the high speed performance.

  However, in each of the conventional pneumatic tires described above, it is possible to suppress deformation due to the protrusion of the tread portion, but there is a problem that it is insufficient to suppress heat generated by the tire being distorted during high speed traveling. there were.

  In particular, in each conventional pneumatic tire, when a hybrid cord is used for the belt protective layer, the skeleton member is configured due to insufficient heat suppression caused by distortion of the tire during high-speed running. The shear strain applied to the rubber material to be increased increases, and heat separation (peeling) due to the shear strain occurs.

  Therefore, the present invention has been made in view of the above-described situation, and an object thereof is to provide a pneumatic tire that can improve high-speed performance, particularly high-speed durability and high-speed running stability.

  In order to solve the above-described problems, the present invention has the following features. First, the invention according to the first aspect of the present invention includes a pair of bead portions including at least a bead core, a carcass layer folded around the bead core, a belt layer disposed on the outer side in the tire radial direction of the carcass layer, and a belt A pneumatic tire comprising a belt end rubber disposed at a belt end that is both ends of the outer layer in the tread width direction, and a tread portion disposed on the outer side in the tire radial direction of the outer belt layer and in contact with a road surface, The belt layer is disposed on the outer side in the tire radial direction of the carcass layer, and is disposed on the outer side in the tire radial direction of the inner belt layer with the inner cord covered with the inner rubber material, and the outer cord is covered with the outer rubber material. An outer belt layer, and the belt end rubber includes an inner belt end rubber disposed between the carcass layer and the inner belt layer, and the inner belt layer and the outer belt layer. An intermediate belt end rubber disposed between the belt layer and the outer belt layer, and an outer belt end rubber disposed between the outer belt layer and the tread portion. The gist is that the rubber is formed of a rubber material having a smaller loss tangent (tan δ) than the inner rubber material and the outer rubber material.

  Here, the loss tangent (tan δ) is a strip sample having a width of 2.5 mm and a thickness of 0.5 mm using a testing machine (Iwamoto Seisakusho Viscoelastic Spectrometer), vibration 50 Hz, initial strain 3%, dynamic The value measured under a test of 1% static strain and a temperature of 25 degrees is shown.

  According to this feature, the inner belt end rubber, the intermediate belt end rubber, and the outer belt end rubber are formed of a rubber material having a loss tangent (tan δ) smaller than that of the inner rubber material and the outer rubber material, and thus the deformation amount. Since the damage to the skeletal members (for example, carcass layer and belt layer) that occurs when the tire becomes large can be suppressed, deformation due to the protruding tread portion can be suppressed, and the tire can be distorted during high-speed driving. It is possible to suppress the heat generated by.

  In addition, since the heat generated by the tire being distorted during high-speed running can be suppressed, the shear strain applied to the rubber material constituting the skeleton member can be reduced, thus reducing the occurrence of heat separation (peeling). Can be made.

  As a result, high-speed performance, particularly high-speed durability and high-speed performance, without affecting the various performances such as low rolling and high-speed driving, without causing deterioration of rolling resistance. Travel stability can be improved.

  In another aspect of the invention, the loss tangent (tan δ) of the inner belt end rubber, the intermediate belt end rubber, and the outer belt end rubber is 70 to 100% with respect to the loss tangent (tan δ) of the inner rubber material and the outer rubber material. It is a summary.

  Another aspect of the invention is summarized in that the inner belt end rubber, the intermediate belt end rubber, and the outer belt end rubber have a thickness (T) of 0.5 to 1.0 mm.

  According to another aspect of the invention, the inner belt end rubber and the intermediate belt end rubber have a width (W1) in a cross section in the tread width direction of 3 to 25% with respect to the width (α) of the inner belt layer. The gist is that the width (W2) of the rubber in the tread width direction cross section is 3 to 25% with respect to the width (β) of the outer belt layer.

  The gist of the invention relating to the other features is that the inner belt end rubber and the intermediate belt end rubber are integrally formed and wrap the inner belt end portion inward in the tread width direction.

  The invention according to another feature further includes a belt protective layer that is disposed on the outer side in the tire radial direction of the outer belt layer and covers the outer belt layer toward the inner side in the tire radial direction, and the outer belt end rubber includes the outer belt layer and the belt. The gist is that it is disposed between the protective layer.

  According to the present invention, it is possible to provide a pneumatic tire that can improve high-speed performance, particularly high-speed durability and high-speed running stability.

  Next, an example of the pneumatic tire 1 according to the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions are different from actual ones. Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(Composition of pneumatic tire)
First, the configuration of the pneumatic tire will be described with reference to FIG. FIG. 1 is a partially exploded perspective view of a pneumatic tire according to the present embodiment.

  As shown in FIG. 1, a pneumatic tire 1 is folded around a pair of bead portions 3 including at least a bead core 3a contacting a rim portion (not shown) of the wheel, and the bead core 3a. And a carcass layer 5 serving as one skeleton. An inner liner 7 which is a highly airtight rubber layer corresponding to a tube is provided inside the carcass layer 5 in the tire radial direction.

  On the outer side in the tire radial direction of the carcass layer 5, a belt layer 9 that reinforces a tread portion 15 described later and holds the shape of the pneumatic tire 1 is provided. The belt layer 9 is disposed on the outer side in the tire radial direction of the carcass layer 5, and is disposed on the outer side in the tire radial direction of the inner belt layer 9A with the inner cord covered with an inner rubber material. And an outer belt layer 9B covered with an outer rubber material.

  Belt end rubber 11 is provided at belt end portions that are both ends of the belt layer 9 (inner belt layer 9A and outer belt layer 9B) on the outer side in the tread width direction. The details of the belt end rubber 11 will be described later.

  A belt protective layer 13 is provided on the outer side of the belt layer 9 in the tire radial direction so as to cover the outer belt layer 9B toward the inner side in the tire radial direction. The belt protective layer 13 includes an inner belt protective layer 13A disposed on the outer side in the tire radial direction of the outer belt layer 9B, and an outer belt protective layer 13B disposed on the outer side in the tire radial direction of the inner belt protective layer 13A. is doing.

  For the belt protective layer 13 (the inner belt protective layer 13A and the outer belt protective layer 13B), in order to further improve the high speed performance, it is preferable to use a hybrid cord in which a nylon cord and an aramid cord are twisted together.

  On the outer side in the tire radial direction of the belt protective layer 13 (belt layer 9), a tread portion 15 that has a plurality of grooves (for example, ribs and blocks) forming a tread pattern and is in contact with the road surface is provided.

(Configuration of belt end rubber)
Next, details of the above-described belt end rubber will be described with reference to FIGS. FIG. 2 is a cross-sectional view in the tread width direction of the pneumatic tire according to the present embodiment, and FIG. 3 is an enlarged cross-sectional view in the tread width direction of the pneumatic tire according to the present embodiment.

  As shown in FIGS. 2 and 3, the belt end rubber 11 is formed between the inner belt end rubber 11A disposed between the carcass layer 5 and the inner belt layer 9A, and between the inner belt layer 9A and the outer belt layer 9B. An intermediate belt end rubber 11B, and an outer belt end rubber 11C disposed between the outer belt layer 9B and the belt protective layer 13 (inner belt protective layer 13A).

  The inner belt end rubber 11A, the intermediate belt end rubber 11B, and the outer belt end rubber 11C (hereinafter simply referred to as “belt end rubber 11”) are an inner rubber material constituting the inner belt layer 9A and an outer rubber constituting the outer belt layer 9B. The rubber material is smaller in loss tangent (tan δ) than the material.

  The loss tangent (tan δ) of the belt end rubber 11 is preferably 70 to 100% with respect to the loss tangent (tan δ) of the inner rubber material and the outer rubber material. If the loss tangent (tan δ) of the belt end rubber 11 is smaller than 70% with respect to the loss tangent (tan δ) of the inner rubber material and the outer rubber material, the heat generated due to distortion of the tire during high-speed running is suppressed. Is difficult. Further, if the loss tangent (tan δ) of the belt end rubber 11 is larger than 100% with respect to the loss tangent (tan δ) of the inner rubber material and the outer rubber material, the tread portion 15 has a large force applied to the belt end portion. It is impossible to suppress deformation due to protrusion, and it is difficult to reduce failures such as shear strain.

  The thickness (T) of the belt end rubber 11 is preferably 0.5 to 1.0 mm. If the thickness (T) of the belt end rubber 11 is smaller than 0.5 mm, it is impossible to suppress the deformation due to the protruding of the tread portion 15 when the force applied to the belt end portion is large. It is difficult to reduce such failures. In addition, when the thickness (T) of the belt end rubber 11 is larger than 1.0 mm, heat generated by the tire being distorted during high-speed running increases and shear strain increases. The growth rate of heat separation (peeling) due to shear strain may be increased.

  The width (W1) of the inner belt end rubber 11A and the intermediate belt end rubber 11B in the cross section in the tread width direction is 3 to 25% with respect to the width (α) of the inner belt layer 9A, and the tread width of the outer belt end rubber 11C. The width (W2) in the directional cross section is preferably 3 to 25% with respect to the width (β) of the outer belt layer 9B.

  The inner belt end rubber 11A and the intermediate belt end rubber 11B have a width (W1) in the cross section in the tread width direction and a width (W2) in the cross section in the tread width direction of the outer belt end rubber 11C. If it is smaller than 3%, it is impossible to suppress deformation due to the protrusion of the tread portion 15 when the force applied to the belt end is large, and it is difficult to reduce failures such as shear strain. .

  Further, the width (W1) of the inner belt end rubber 11A and the intermediate belt end rubber 11B in the tread width direction cross section and the width (W2) of the outer belt end rubber 11C in the tread width direction cross section are the width (α) of the inner belt layer 9A. On the other hand, if it is larger than 25%, the heat generated by the tire being distorted during high-speed running will increase, and the shear strain will increase, increasing the growth rate of heat separation (peeling) due to this shear strain. May end up.

(Action / Effect)
In the following, the background to the adoption of the configuration of the pneumatic tire 1 described above will be described together with the operation. When the pneumatic tire 1 rotates, distortion occurs from the front side where the tread portion 15 contacts the road surface, and shear distortion occurs between the skeleton members (for example, the carcass layer 5, the belt layer 9, and the belt protective layer 13). At this time, if the pneumatic tire 1 is provided with the belt protective layer 13, the shear strain generated between the outer belt layer 9 </ b> B and the inner belt protective layer 13 </ b> A is particularly large, and distortion occurs when the tread portion 15 is separated from the road surface. Becomes smaller. As a result, it was found that the shear strain generated between the skeleton members is reduced, but the high-speed performance is improved.

  Therefore, according to the pneumatic tire 1 according to the above-described embodiment, the belt end rubber 11 (the inner belt end rubber 11A, the intermediate belt end rubber 11B, and the outer belt end rubber 11C) is replaced with the belt rubber material (the inner rubber material). And the outer rubber material) are made of a rubber material having a smaller loss tangent (tan δ) than that of the outer rubber material, so that damage to the skeleton member that occurs when the amount of deformation increases can be reduced. It is possible to suppress the deformation caused by the sticking out and to suppress the heat generated when the tire is distorted during high speed running.

  In addition, since the heat generated by the tire being distorted during high-speed running can be suppressed, the shear strain applied to the rubber material constituting the skeleton member can be reduced, thus reducing the occurrence of heat separation (peeling). Can be made.

  As a result, high-speed performance, particularly high-speed durability and high-speed performance, without affecting the various performances such as low rolling and high-speed driving, without causing deterioration of rolling resistance. Travel stability can be improved.

  Further, since the loss tangent (tan δ) of the belt end rubber 11 is 70 to 100% with respect to the loss tangent (tan δ) of the belt rubber material, the deformation due to the protrusion of the tread portion 15 can be further suppressed. Further, it is possible to further suppress heat generated when the tire is distorted during high-speed traveling.

  Moreover, since the thickness (T) of the belt end rubber 11 is 0.5 to 1.0 mm, the shear strain applied to the rubber material constituting the skeleton member can be further reduced, so that heat separation (peeling) ) Can be reduced.

  Further, the width (W1) of the inner belt end rubber 11A and the intermediate belt end rubber 11B in the cross section in the tread width direction is 3 to 25% with respect to the width (α) of the inner belt layer 9A. When the width (W2) in the cross section in the tread width direction is 3 to 25% with respect to the width (β) of the outer belt layer 9B, failure such as shear strain can be further reduced, and the tire is at high speed running. It is possible to further suppress heat generated due to distortion.

  Furthermore, by using a hybrid cord in which a nylon cord and an aramid cord are twisted together for the belt protective layer 13 (the inner belt protective layer 13A and the outer belt protective layer 13B), high speed performance (especially high speed durability and high speed running stability). Property) can be further improved.

(Example of change)
The belt end rubber 11 according to the above-described embodiment has been described as having the inner belt end rubber 11A, the intermediate belt end rubber 11B, and the outer belt end rubber 11C, but may be modified as follows. . In addition, the same code | symbol is attached | subjected to the same part as the pneumatic tire 1 which concerns on embodiment mentioned above, and a different part is mainly demonstrated.

  FIG. 4 is an enlarged sectional view in the tread width direction of a pneumatic tire according to a modified example. As shown in FIG. 4, the belt end rubber 11 includes an enveloping belt end rubber 17 that wraps inner belt end portions that are both ends of the inner belt layer 9A on the outer side in the tread width direction toward the inner side in the tread width direction, and an outer belt. The outer belt end rubber 11C is disposed between the layer 9B and the belt protective layer 13 (inner belt protective layer 13A).

  In other words, the inner belt end rubber 11A and the intermediate belt end rubber 11B according to the above-described embodiment are integrally formed in the enveloping belt end rubber 17, and the inner belt end is encased inward in the tread width direction. It is out.

Of course, even in this case, the enveloping belt end rubber 17 is formed of a rubber material having a smaller loss tangent (tan δ) than the inner rubber material and the outer rubber material. The loss tangent (tan δ) of the enveloping belt end rubber 17 is preferably 70 to 100% with respect to the loss tangent (tan δ) of the inner rubber material and the outer rubber material.

  Furthermore, the thickness (T1) of the enveloping belt end rubber 17 is preferably 0.5 to 1.0 mm. Moreover, it is preferable that the width (W1) in the tread width direction cross section of the enveloping belt end rubber 17 is 3 to 25% with respect to the width (α) of the inner belt layer 9A.

[Other Embodiments]
Although the contents of the present invention have been disclosed through the embodiments of the present invention as described above, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention.

  Specifically, although the pneumatic tire 1 described above has been described as including the belt protective layer 13, the pneumatic tire 1 is not limited thereto, and the belt protective layer 13 may not be included. In this case, the outer belt end rubber 11C is disposed between the outer belt layer 9B and the tread portion 15.

  From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

Next, in order to further clarify the effects of the present invention, the results of tests performed using the pneumatic tires according to Comparative Examples and Examples 1 and 2 to which the present invention is applied will be described. Data relating to each pneumatic tire is shown in Table 1.

  As shown in Table 1, in the pneumatic tire according to the comparative example, a nylon cord is used for the belt protective layer, and the loss coefficient (tan δ) of the belt end rubber is equal to the loss tangent (tan δ) of the inner rubber material and the outer rubber material. In contrast, it is 100%.

  In the pneumatic tire according to Example 1, nylon cord is used for the belt protective layer, and the loss coefficient (tan δ) of the belt end rubber is 81% with respect to the loss tangent (tan δ) of the inner rubber material and the outer rubber material. .

  In the pneumatic tire according to Example 2, a hybrid cord is used for the belt protective layer, and the loss coefficient (tan δ) of the belt end rubber is 81% with respect to the loss tangent (tan δ) of the inner rubber material and the outer rubber material. .

The results of high speed durability and high speed running stability of the pneumatic tires according to this comparative example and Examples 1 and 2 will be described.

<High speed durability>
Each pneumatic tire (tyre size “235 / 35ZR19”, wheel size “8J × 19”) is mounted on a drum having a diameter of 3 m and pressed against the drum under conditions of an internal pressure of 300 kPa and a load of 650 kN, as shown in Table 2. As described above, the time until the failure occurred and the failure occurrence rate were evaluated by increasing the speed from 210 km / h.

  As a result, the pneumatic tires according to Examples 1 and 2 are superior to the pneumatic tire according to the comparative example in that it takes time until a failure occurs, and the failure occurrence speed is high, so that the high-speed durability is excellent. I understood that.

<High-speed running stability>
Each pneumatic tire is mounted on a vehicle, and the test course runs at a high speed of 120 to 200 km / h, that is, responsiveness (so-called steering feeling) and convergence when moving to the adjacent lane (one lane). (A so-called feeling of fit in the moved lane) was evaluated by a driver (full score of 10).

  Each pneumatic tire has a front tire size “235 / 35ZR19”, a front wheel size “8J × 19”, a front internal pressure “230 kPa”, a rear tire size “305 / 30ZR19”, a rear wheel size “11J × 19”, a rear The internal pressure is “270 kPa”.

  As a result, it was found that the pneumatic tires according to Examples 1 and 2 were superior to the pneumatic tire according to the comparative example in high-speed running stability such as responsiveness and convergence at a high speed.

1 is a partially exploded perspective view of a pneumatic tire according to the present embodiment. It is a tread width direction sectional view of the pneumatic tire concerning this embodiment. It is a tread width direction expanded sectional view of the pneumatic tire concerning this embodiment. It is a tread width direction expanded sectional view of the pneumatic tire concerning the example of a change.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Pneumatic tire, 3 ... Bead part, 3a ... Bead core, 5 ... Carcass layer, 7 ... Inner liner, 9 ... Belt layer, 9A ... Inner belt layer, 9B ... Outer belt layer, 11 ... Belt end rubber, 11A ... Inner belt end rubber, 11B ... Intermediate belt end rubber, 11C ... Outer belt end rubber, 13 ... Belt protective layer, 13A ... Inner belt protective layer, 13B ... Outer belt protective layer, 15 ... Tread portion, 17 ... Enveloping belt end Rubber

Claims (6)

A pair of bead portions including at least a bead core, a carcass layer folded around the bead core, a belt layer disposed on the outer side in the tire radial direction of the carcass layer, and both end portions on the outer side in the tread width direction of the belt layer. A pneumatic tire comprising a belt end rubber disposed at a belt end portion and a tread portion disposed on the outer side in the tire radial direction of the outer belt layer and in contact with a road surface,
The belt layer is disposed on the outer side in the tire radial direction of the carcass layer, and is disposed on the outer side in the tire radial direction of the inner belt layer with the inner cord covered with an inner rubber material, and the outer cord is disposed on the outer rubber material. And an outer belt layer coated with
The belt end rubber includes an inner belt end rubber disposed between the carcass layer and the inner belt layer, an intermediate belt end rubber disposed between the inner belt layer and the outer belt layer, and An outer belt end rubber disposed between the outer belt layer and the tread portion;
The inner belt end rubber, the intermediate belt end rubber, and the outer belt end rubber are formed of a rubber material having a smaller loss tangent (tan δ) than the inner rubber material and the outer rubber material. Tires.   The loss tangent (tan δ) of the inner belt end rubber, the intermediate belt end rubber, and the outer belt end rubber is 70 to 100% with respect to the loss tangent (tan δ) of the inner rubber material and the outer rubber material. The pneumatic tire according to claim 1.   The air according to claim 1 or 2, wherein a thickness (T) of the inner belt end rubber, the intermediate belt end rubber, and the outer belt end rubber is 0.5 to 1.0 mm. Tires. The width (W1) in the cross-section in the tread width direction of the inner belt end rubber and the intermediate belt end rubber is 3 to 25% with respect to the width (α) of the inner belt layer,
The width (W2) in the cross section in the tread width direction of the outer belt end rubber is 3 to 25% with respect to the width (β) of the outer belt layer. The pneumatic tire according to item 1.   The inner belt end rubber and the intermediate belt end rubber are formed integrally, and wrap the end portion of the inner belt toward the inner side in the tread width direction. The pneumatic tire according to item. A belt protective layer that is disposed on the outer side in the tire radial direction of the outer belt layer and covers the outer belt layer inward in the tire radial direction;
The pneumatic tire according to any one of claims 1 to 5, wherein the outer belt end rubber is disposed between the outer belt layer and the belt protective layer.

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