JP2005231413A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire eccentric abrasion of a shoulder part while maintaining durability of a belt layer. <P>SOLUTION: This pneumatic tire 1 has a carcass layer 2, a belt layer 3 arranged outward in a tire radial direction to the carcass layer 2, and a tread part T formed outward in the tire radial direction on the belt layer 3. The belt layer 3 is formed by laminating a first belt material 31 restraining a growth phenomenon of a tire diameter due to an internal pressure and a second belt material 32 made of a steel wire material and forming an angle in a steel wire direction of the steel wire material in a range of 30 to 45 degrees relative to a tire peripheral direction. When the tread part T is seen from the tire radial direction, the second belt material 32 is overlaid on the first material 31, and the ends of the second belt material are protruded from both widthwise edges of the tread part T. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire that can suppress uneven wear of a shoulder portion while maintaining durability of a belt layer.

  In recent years, flat tires having a special belt structure are often used in heavy duty pneumatic tires. In such flat tires, uneven wear (shoulder fall wear) occurs in the shoulder portion by use, and technical improvements for suppressing this are required. In general, in a pneumatic tire, (1) the distribution of the contact pressure is properly maintained, and (2) the outer surface of the tread portion is formed in a convex shape in order to relieve the stress caused by the lateral force when turning the tire. Yes. For this reason, the crown center portion and the shoulder portion have different tire diameters. In such a configuration, the ground reaction force acting on the tread portion at the time of rolling of the tire is directed to the front side (driving side) with respect to the tire traveling direction at the crown center portion, and toward the rear side (braking side) at the shoulder portion. As a result, there is a problem that the wear rate at the shoulder edge increases and uneven wear occurs.

  In order to solve such a problem, a technique described in Patent Document 1 is known for a conventional pneumatic tire. In a conventional pneumatic tire, a belt layer is constituted by a plurality of plies (belt materials), and a hard rubber layer is provided so as to overlap the belt layer. This hard rubber layer is made of a rubber material whose 100% modulus is 3 to 10 times that of the tread rubber, and the outermost ends in the width direction of the ply of the belt layer having the widest width. It arrange | positions so that it may each overlap with a part. In the conventional pneumatic tire, this configuration improves the shear rigidity of the tread portion at the belt layer edge and suppresses uneven wear of the shoulder portion. However, the conventional pneumatic tire has a problem that a crack occurs at the end portion of the disposed hard rubber layer.

JP 2002-274123 A

  Therefore, the present invention has been made in view of the above, and an object thereof is to provide a pneumatic tire capable of suppressing uneven wear of the shoulder portion while maintaining durability of the belt layer.

  In order to achieve the above object, a pneumatic tire according to the present invention is formed on a carcass layer, a belt layer disposed on the outer side in the tire radial direction with respect to the carcass layer, and on the outer side in the tire radial direction with respect to the belt layer. In the pneumatic tire having a tread portion, the belt layer includes a first belt material that suppresses a tire diameter growth phenomenon due to internal pressure, and a steel wire material, and a steel wire direction of the steel wire material is a tire circumferential direction. The second belt material is formed by laminating a second belt material having an angle within a range of 30 to 45 degrees with respect to the tread portion from the tire radial direction. It arrange | positions so that it may overlap, and it may be arrange | positioned so that the edge part may protrude from the both widths of the said tread part.

  In this pneumatic tire, the width of the second belt material constituting the belt layer is larger than the width of the tread portion, and the end of the second belt material is arranged so as to protrude from both widths of the tread portion. Therefore, there is an advantage that the shoulder portion is reinforced and the uneven wear is effectively suppressed. Further, the second belt material is made of a steel wire material and the steel wire direction of the steel wire material forms an angle in the range of 30 degrees to 45 degrees with respect to the tire circumferential direction, so that the end portion is not easily broken. . Thereby, there exists an advantage by which durability of a belt layer is maintained. The first belt material is a so-called tension member belt, and may be formed of a steel wire material having a linear shape, a wave shape, or other shapes, or may be formed of a tape-shaped member (band-shaped member). Further, the second belt material may have a single shape or a split shape.

  The pneumatic tire according to the present invention includes a carcass layer, a belt layer disposed on the outer side in the tire radial direction with respect to the carcass layer, and a tread portion formed on the outer side in the tire radial direction with respect to the belt layer. In the pneumatic tire, the belt layer is formed by laminating a first belt material and a second belt material made of a steel wire material, and an angle formed by a steel wire direction of the steel wire material with respect to a tire circumferential direction is a belt angle. The belt angle θ1 of the first belt material is in the range of 0 to 5 degrees, and the belt angle θ2 of the second belt material is in the range of 30 to 45 degrees, where θ is the tread portion. When the second belt material is seen through from the tire radial direction, the width dimension of the second belt material is larger than the width dimension of the ground contact surface of the tread portion, and the end portion has both widths of the tread portion. Characterized in that it is arranged in Rahamidasu so.

  In this pneumatic tire, the width of the second belt material constituting the belt layer is larger than the width of the tread portion, and the end of the second belt material is arranged so as to protrude from both widths of the tread portion. Therefore, there is an advantage that the shoulder portion is reinforced and the uneven wear is effectively suppressed. Further, the second belt material is made of a steel wire material and the steel wire direction of the steel wire material forms an angle in the range of 30 degrees to 45 degrees with respect to the tire circumferential direction, so that the end portion is not easily broken. . Thereby, there exists an advantage by which durability of a belt layer is maintained.

  In the pneumatic tire according to the present invention, the second belt material is disposed on the outer side in the tire radial direction of the first belt material.

  In this pneumatic tire, the second belt material presses and fixes the first belt material from the outer side in the tire radial direction by the tension. Thereby, since the deformation | transformation to the width direction of a 1st belt material is suppressed, there exists an advantage by which the deformation | transformation of the tread part at the time of tire contact is suppressed and the uneven wear of the shoulder part Sh is suppressed synergistically.

  In the pneumatic tire according to the present invention, the belt layer is formed by sandwiching the second belt material between a pair of the first belt materials.

  According to this invention, the width dimension of the second belt material constituting the belt layer is larger than the width dimension of the tread portion, and the end portion of the second belt material is disposed so as to protrude from both widths of the tread portion. Therefore, there is an advantage that the shoulder portion is reinforced and the uneven wear is effectively suppressed. Further, the second belt material is made of a steel wire material and the steel wire direction of the steel wire material forms an angle in the range of 30 degrees to 45 degrees with respect to the tire circumferential direction, so that the end portion is not easily broken. . Thereby, there exists an advantage by which durability of a belt layer is maintained.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements of the embodiments described below include those that can be easily replaced by those skilled in the art or those that are substantially the same.

  1 and 2 are a cross-sectional perspective view (FIG. 1) and a meridian cross-sectional view (FIG. 2) showing a pneumatic tire according to an embodiment of the present invention. The pneumatic tire 1 is a pneumatic radial tire for heavy loads, and includes a carcass layer 2 and a belt layer 3. In this pneumatic tire 2, since the belt layer 3 has a structure to be described later, (1) durability of the belt layer 3 is improved, and (2) uneven wear of the shoulder portion Sh is effectively suppressed. Characterized by points. Note that the structure of the belt layer 3 is particularly preferably applied to a heavy-duty pneumatic tire having a low flatness ratio (70% or less).

  In this pneumatic tire 1, the carcass layer 2 is formed to be stretched in a toroidal shape with respect to a pair of bead portions (not shown), and constitutes a tire skeleton. The belt layer 3 has at least a three-layer structure formed by laminating a plurality of belt materials 31 and 32, and is disposed on the outer periphery in the tire radial direction of the carcass layer 2 to cover the carcass layer 2 in the tire circumferential direction. And the rubber material is arrange | positioned in the tire radial direction outer periphery of the belt layer 3, and the tread part T is formed.

  Here, the belt layer 3 includes first belt materials 31 and 31 and a second belt material 32, and is configured by sandwiching and laminating the second belt material 32 between the pair of first belt materials 31 and 31. Specifically, first, one first belt member 31 is wound around the outer periphery of the carcass layer 2 in the tire radial direction, the second belt member 32 is wound around the outer periphery, and the other first belt member is wound around the outer periphery. The belt layer 3 is formed by winding 31 (see FIGS. 1 and 2).

  The first belt materials 31 and 31 are configured by arranging a plurality of steel wire materials made of a material having a strand diameter smaller than that of a general belt material and a finer twist pitch in order to increase the elongation of the wire itself. As a single substantially band-like shape. Since the first belt material 31 is made of such a steel wire material, its circumferential length (full length) can be extended in the longitudinal direction at a rate of 7% to 8%. Further, the first belt members 31 and 31 are configured such that the steel wire direction of the steel wire material forms an angle of 0 degree to 5 degrees with respect to the longitudinal direction (substantially parallel). As a result, the first belt material 31 has an angle between the steel wire direction of the steel wire material and the tire circumferential direction (hereinafter referred to as a belt angle θ1) in the range of 0 degrees to 5 degrees in the installed state. (The steel wire direction of the steel wire material is substantially parallel to the tire circumferential direction). Further, the first belt material 31 has an action of suppressing a tire diameter growth phenomenon due to internal pressure (a phenomenon in which the tire expands in the radial direction and the tire contact surface becomes a substantially spherical surface) by its tension. That is, the first belt materials 31 and 31 function as so-called tension member belts. Thereby, the flatness of the tire ground contact surface is ensured.

  On the other hand, the second belt member 32 is configured by arranging a plurality of steel wire members, and has a single substantially belt-like shape as a whole. The second belt member 32 is configured such that the steel wire direction of the steel wire member forms an angle of 30 degrees to 45 degrees with respect to the longitudinal direction. Thereby, the second belt member 32 is in an installed state so that an angle between the steel wire direction of the steel wire member and the tire circumferential direction (hereinafter referred to as a belt angle θ2) is in a range of 30 degrees to 45 degrees. It is configured. The second belt member 32 has a width dimension BW applied in the tire axial direction that is larger than the width dimension TW of the ground contact surface of the tread portion T and 1.05 times or less the width dimension TW of the tread portion T. In other words, the second belt member 32 is configured such that the width dimension BW thereof includes the width dimension TW of the tread portion T when the tread portion T is seen through from the tire radial direction. Further, the second belt member 32 is disposed such that an end portion thereof protrudes from the both widths of the tread portion T toward the shoulder portion Sh when the tread portion T is seen through from the tire radial direction.

  In addition, the width dimension TW of the tread portion T refers to the dimension of the contact width in a state where the pneumatic tire 1 is mounted on the specified rim and is applied with the specified internal pressure and the specified load. These specified rim, specified internal pressure, and specified load are defined in standards issued by JATMA (Japan), for example.

[Function and effect]
In the pneumatic tire 1, the belt layer 3 includes the second belt material 32, and the width dimension BW of the second belt material 32 is configured to be larger than the width dimension TW of the tread portion T. Further, when the tread portion T is seen through from the tire radial direction, the end portion of the second belt member 32 is configured to protrude from the end portion of the tread portion T in the width direction. Therefore, in particular, the shoulder portion Sh of the tread portion T is reinforced by the second belt member 32, and the shear rigidity thereof is increased. Thereby, since the shear deformation of the shoulder portion Sh during tire rolling is reduced, there is an advantage that uneven wear of the shoulder portion Sh is effectively suppressed.

  Further, the pneumatic tire 1 is configured such that the width dimension BW of the second belt member 32 is 1.05 times or less of the width dimension TW of the tread portion T. The advantage of suppressing adverse effects caused by the fact that the width dimension BW of the belt 2 is larger than the width dimension TW of the tread portion T) (if the width dimension BW of the second belt member 32 is too large, cracks are likely to occur in the shoulder portion Sh). There is.

  Further, as described above, the second belt member 32 that reinforces the shoulder portion Sh is configured such that the belt angle θ2 is in the range of 30 degrees to 45 degrees. Accordingly, since the tension hardly acts on the second belt member 32 during rolling of the tire, separation (breaking) of the end portion of the second belt member 32 is suppressed. Thereby, there exists an advantage which the durability of the belt layer 3 improves compared with the conventional pneumatic tire with which the hard rubber layer was easy to fracture | rupture.

  In the pneumatic tire 1, the second belt member 32 is disposed between the first belt members 31 and 31. And the 2nd belt material 32 presses down and fixes the 1st belt materials 31 and 31 from the tire radial direction outer side with the tension | tensile_strength. Then, although the first belt members 31 and 31 tend to shrink greatly in the width direction when the tire contacts the ground, the first belt members 31 and 31 are fixed by the second belt member 32, so that deformation in the width direction is suppressed. Thereby, since deformation of the tread portion T at the time of tire contact is suppressed, there is an advantage that uneven wear of the shoulder portion Sh is synergistically suppressed.

  Moreover, in this pneumatic tire 1, the belt layer 3 can be extended by a predetermined amount with respect to the tire circumferential direction. Specifically, the first belt members 31 and 31 can extend in the circumferential direction at a ratio of 7% to 8% in the longitudinal direction depending on the material, and the second belt member 32 has a belt angle θ2 ( θ2 = 30 degrees to 45 degrees), the structure can be extended in the longitudinal direction larger than the first belt material 31. In such a configuration, when the tire expands during tire vulcanization molding, the belt layer 3 expands accordingly. Thereby, there exists an advantage which can ensure the softness | flexibility of the belt layer 3 required at the time of tire vulcanization molding.

[Additional items]
In this pneumatic tire 1, the first belt members 31, 31 have a single band shape formed by arranging a plurality of steel wire members. This is because the installation process of the belt layer 3 at the time of tire molding is performed. It is preferable because it is easy. However, the present invention is not limited to this, and the first belt material 31 may be configured by (1) a single steel wire material being wound around the carcass layer 2 or the second belt material 32 seamlessly in an annular shape. (2) You may comprise by a tape-shaped member (strip | belt-shaped member) (illustration omitted). Moreover, the 1st belt material 31 may be comprised with the linear steel wire material, and may be comprised with the wave-shaped steel wire material.

  Moreover, in this pneumatic tire 1, the second belt member 32 has a single belt-like shape formed by arranging a plurality of steel wire members, which is a conventional air that reinforces the shoulder portion Sh with a hard rubber layer. Compared to a tire, it is preferable in that the installation process of the belt layer 3 at the time of tire molding is easy. However, the present invention is not limited to this, and the second belt member 32 may be formed in a split shape (a state in which the pair of second belt members 32 are disposed with respect to the shoulder portions Sh on both the left and right sides). In such a configuration, when the tread portion T is seen through from the tire radial direction, (1) the second belt member 32 is disposed so as to overlap the first belt member 31 in a planar manner, and (2) the second belt. It is preferable that the end portion of the material 32 is disposed so as to protrude from both widths of the tread portion T toward the shoulder portion Sh.

[performance test]
FIG. 3 is a table showing the results of the performance test of the pneumatic tire according to the present invention. In this performance test, a pneumatic tire 1 in which the width BW and the belt angle θ2 of the second belt member 32 are changed is prototyped, and the wear resistance of the tread portion T (“Sh shoulder wear resistance” in the figure) and Evaluation was made with respect to the durability of the belt layer 3 (shown as “belt edge resistance” in the figure) and “center wear resistance”.

  The pneumatic tire 1 used in this performance test has a tire size of 435 / 45R22.5, is assembled with a rim according to JATMA normal conditions, and is loaded with a specified internal pressure and a specified load. Further, “Sh shoulder wear resistance” and “center wear resistance” in the figure are values obtained by measuring the remaining amounts of the grooves in the shoulder portion Sh and the center crown portion, respectively. Further, “belt edge separation resistance” in the figure is an evaluation regarding edge breakage (separation) of the second belt member 32, and was evaluated by comparing the traveling distance of the indoor drum test. Moreover, these evaluations are represented by indexes with the conventional example 1 as a reference (100), and it is preferable that the numerical value is large.

  The pneumatic tires of Conventional Example 1 and Conventional Example 2 each have only the first belt material 31 and do not have the second belt material 32. Further, in the pneumatic tire of Conventional Example 1, the first belt material 31 is made of a wavy steel wire material, and in the pneumatic tire of Conventional Example 2, the first belt material 31 is a straight steel wire material. It is comprised by.

  The pneumatic tire 1 of Invention Example 1 and Invention Example 2 is the pneumatic tire 1 described in Example 1. In these pneumatic tires 1, the width dimension BW of the second belt member 32 is configured to be 1.00 times and 1.05 times the width dimension TW of the tread portion T (“BW / TW” in the figure). The belt angle θ2 is configured to be 30 degrees and 45 degrees, respectively. In this performance test, when BW / TW = 1.05, the width dimension BW of the second belt member 32 is about 10 mm longer than the width dimension TW of the tread portion T.

  In the pneumatic tires of Comparative Example 1 and Comparative Example 2, the belt angle θ2 is changed to 25 degrees and 50 degrees with respect to the pneumatic tire 1 of Invention Example 1 and Invention Example 2.

  As shown in the test results, the pneumatic tires 1 of the invention example 1 and the invention example 2 are compared with the pneumatic tires of the pneumatic tires of the conventional example 1 and the conventional example 2, and the wear resistance of the tread portion T and the belt. It can be seen that the durability of the layer 3 is improved.

  According to the knowledge of the inventors, by setting the belt angle θ2 of the second belt member 32 to 30 degrees or more, a position away from the ground contact region of the tread portion T by a predetermined angle (approximately 60 degrees) in the tire circumferential direction. Thus, the circumferential displacement between the second belt material 32 and the first belt material 31 during tire rolling is suppressed. Further, by setting the belt angle θ2 of the second belt member 32 to 45 degrees or less, the shear stress acting on the second belt member 32 due to the load during tire rolling is reduced. And it is thought by these that the fracture | rupture of the 2nd belt material 32 (especially the both ends) is suppressed effectively, and the durability of the belt layer 3 improves.

  As described above, the pneumatic tire according to the present invention is useful in that the uneven wear of the shoulder portion can be suppressed while maintaining the durability of the belt layer.

It is a section perspective view showing a pneumatic tire concerning Example 1 of this invention. It is sectional drawing of the meridian direction which shows the pneumatic tire concerning Example 1 of this invention. It is a graph which shows the result of the performance test of the pneumatic tire concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Carcass layer 3 Belt layer 31 1st belt material 32 2nd belt material BW Belt layer width dimension Sh Shoulder part T Tread part TW Tread part width dimension θ1, θ2 Belt angle

Claims (4)

In a pneumatic tire having a carcass layer, a belt layer disposed on the outer side in the tire radial direction with respect to the carcass layer, and a tread portion formed on the outer side in the tire radial direction with respect to the belt layer,
The belt layer includes a first belt material that suppresses a tire diameter growth phenomenon due to internal pressure, and a steel wire material, and a steel wire direction of the steel wire material is within a range of 30 to 45 degrees with respect to a tire circumferential direction. It is formed by laminating a second belt material having an angle of
When the tread portion is seen through from the tire radial direction, the second belt material is disposed so as to overlap the first belt material, and the end portion thereof is disposed so as to protrude from both widths of the tread portion. Pneumatic tire characterized by. In a pneumatic tire having a carcass layer, a belt layer disposed on the outer side in the tire radial direction with respect to the carcass layer, and a tread portion formed on the outer side in the tire radial direction with respect to the belt layer,
The belt layer is formed by laminating a first belt material and a second belt material made of a steel wire material,
When the angle formed by the steel wire direction of the steel wire material with respect to the tire circumferential direction is a belt angle θ, the belt angle θ1 of the first belt material is in the range of 0 to 5 degrees, and the second The belt angle θ2 of the belt material is in the range of 30 degrees to 45 degrees,
When the tread portion is seen through from the tire radial direction, the width of the second belt material is larger than the width of the ground contact surface of the tread portion, and the end portion protrudes from both widths of the tread portion. A pneumatic tire characterized by being arranged as described above.   The pneumatic tire according to claim 1 or 2, wherein the second belt member is disposed on the outer side in the tire radial direction of the first belt member.   The pneumatic tire according to any one of claims 1 to 3, wherein the belt layer is formed by sandwiching and stacking the second belt material between a pair of the first belt materials.

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