JP2006130942A - Pneumatic radial tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make maintenance or enhancement of durability at high speed traveling and improvement of load noise by reduction of cavity resonance in a tire compatible. <P>SOLUTION: An end edge of a carcass ply 12 folded/returned at a bead core 24 is arranged so as to be clamped between a belt 14 of a crown part 18 and the carcass ply 12. In a belt reinforcement layer 16 made to the state that end edges at both sides are left, i.e., the state that the central part of the carcass is removed and helically wound with a band-like strip 16A, a clearance is not provided near an end in a tire width direction and a predetermined clearance 28 is provided in a range other than it. Thereby, restriction force of a belt end is increased and a belt central part is easily deformed. The enhancement of high speed durability and improvement of load noise by reduction of cavity resonance in the tire are made compatible. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pneumatic radial tire, and more particularly to a pneumatic radial tire capable of reducing both road noise caused by cavity resonance inside the tire and high-speed durability.

  In pneumatic radial tires, as a technique for improving high-speed durability, weight reduction, steering stability, and riding comfort, a long belt-like ply is spirally provided with a gap between adjacent plies (or While the side edges of adjacent plies are in contact with each other), the belt reinforcing layer is wound around the entire width of the belt layer (see Patent Document 1), and has a single layer of carcass, A technique for removing the portion of the carcass located below the belt layer, that is, separating the carcass to achieve both high speed durability and light weight (see Patent Document 2). There is a technique (see Patent Document 3) in which a portion located below the belt layer is cut out (cut-out) in one carcass to achieve both steering stability and riding comfort.

  Moreover, it has one layer of carcass, extends both ends of the carcass wound around the bead core, and sandwiches it between the carcass and the belt layer located at the crown of the tire (envelope structure), There is a technique (see Patent Document 4) that improves the durability of a tire.

  In the drawing, as shown in FIG. 4, a pneumatic radial tire 100 having a two-layer carcass 102 without hollows and a belt reinforcing layer 104 without gap winding, or as shown in FIG. 3), there is a pneumatic radial tire 200 having two layers of hollow carcass 202 and a belt reinforcing layer 204 without gap winding.

Further, as shown in FIG. 6 (see also Patent Document 2 and Patent Document 4), a pneumatic radial having a separated carcass 302 (cut out) and a belt reinforcing layer 304 without a gap winding. There is a tire 300 or a pneumatic radial tire 400 having a two-layer carcass 402 without hollows and a belt reinforcing layer 404 wound around a gap as shown in FIG.
JP-A-8-192605 Japanese Patent Laid-Open No. 11-32216 Japanese Patent Laid-Open No. 11-11109 Japanese Patent Laid-Open No. 10-100700

  Tires with a road index of 90 or more usually require two layers of carcass, and because the tread width is wide and the belt layer is difficult to deform, cavity resonance is likely to occur inside the tire, which has a peak near 250 Hz. The road noise is 250 Hz.

  Cavity resonance is a vibration wave generated by the resonance of air inside the tire, and the main factor is considered to be deformation in the tire cross-sectional direction. It is considered effective to increase the binding force at the belt end in the direction.

  However, as in the conventional example described above, if the method of separating the central part of the carcass and the method of winding the belt reinforcing layer with a gap are used separately, the binding force at the belt end is strengthened and the cavity resonance is reduced. It was not possible to achieve both.

  In consideration of the above-mentioned facts, the present invention increases the restraint force of the belt end portion while making the belt reinforcing layer gap while preventing the belt end portion reinforcing gap, and also makes the carcass hollow. Accordingly, an object is to achieve both maintenance or improvement of durability at high speed running and improvement of road noise by reducing cavity resonance.

  According to the first aspect of the present invention, at least one layer of carcass ply wound around a bead core disposed between the pair of bead portions in a toroid shape and wound from the inside to the outside, and positioned radially outward of the carcass ply In a pneumatic radial tire having at least one belt and a belt reinforcing layer positioned radially outward of the belt, an edge of the carcass ply wound back by the bead core is positioned at the crown portion. It is arranged between the carcass ply and the belt, and the separation distance between both the edges is configured to be 50 to 80% of the width of the belt closest to the carcass ply in the cross section in the tire width direction. The belt reinforcing layer is a belt-shaped strip having no gap in the vicinity of the end portion in the tire width direction of the belt, and in the vicinity of the end portion. In is characterized in that it is constituted by spirally wound with a gap.

  In the pneumatic radial tire according to claim 1, in a belt reinforcing layer formed by spirally winding a belt-shaped strip while the carcass ply is separated from the edge of the carcass ply, that is, the carcass is hollowed out, Since there is no gap in the vicinity of the end portion and a gap in the other range, the belt center portion is easily deformed, the vibration mode in the tire width direction cross section is changed, and cavity resonance inside the tire is reduced, Road noise is improved.

  In addition, high-speed durability can be maintained or improved by increasing the binding force at the belt end, and both high-speed durability and low road noise are compatible.

  As for the separation distance of the edge of the carcass ply, if the separation distance is less than 50% of the width of the belt, the belt center part is difficult to deform, and cavity resonance inside the tire cannot be reduced, Further, if it exceeds 80%, the meaning of disposing the end of the carcass ply between the carcass ply and the belt is weakened, and rubber peeling at the end of the belt, the end of the carcass ply, the tread portion, etc. easily occurs. 50 to 80% is preferable.

  Here, the vicinity of the end portion in the tire width direction of the belt means a range of 20% in the tire width direction with respect to the width of the belt with the end portion as the center. When a plurality of belts having different widths are used, the range is 20% of the widest belt.

  According to a second aspect of the present invention, in the pneumatic radial tire according to the first aspect, the belt reinforcing layer is within the range of 20 to 60 mm in a tire width direction straddling the end portion in the vicinity of the end portion of the belt. Each layer is wound by two layers, and is wound by one layer in a range other than the vicinity of the end portion.

  In the pneumatic radial tire according to claim 2, the restraining force of the belt end portion is further increased, and the high-speed durability is further improved.

  In the case where the range where the belt reinforcing layer is wound in two layers is less than 20 mm, the binding force at the belt end cannot be increased much more than in the case of the single layer winding despite the fact that the belt is wound in two layers. If it exceeds 60 mm, the belt central portion is difficult to deform and cavity resonance inside the tire cannot be reduced. Therefore, the range is preferably 20 to 60 mm.

  According to a third aspect of the present invention, in the pneumatic radial tire according to the first or second aspect, the winding pitch of the strip-shaped strip in the belt reinforcing layer is other than the vicinity of the end of the belt. It is characterized by being 1.2 to 2 times the width.

  In the pneumatic radial tire according to the third aspect, the winding pitch is optimized, and the high-speed durability can be maintained or improved while reducing the road noise due to the belt central portion being easily deformed.

  When the winding pitch is less than 1.2 times the width of the strip, it becomes difficult to deform the central portion of the belt, and cavity resonance inside the tire cannot be reduced. Since this is insufficient, the range is preferably 1.2 to 2 times.

  A fourth aspect of the present invention is the pneumatic radial tire according to any one of the first to third aspects, wherein the flatness is 70% or less.

  In the pneumatic radial tire according to claim 4, a tire for a large passenger car having a flatness of more than 70% (especially having a road index of 90 or more) in which road noise in the 250 Hz band due to cavity resonance is particularly problematic. Even so, while maintaining high-speed durability, the cavity resonance can be reduced to reduce road noise, and the riding comfort of a vehicle equipped with the pneumatic radial tire can be improved.

  As described above, according to the pneumatic radial tire of the present invention, the belt reinforcing layer is made to be a gap while the belt end portion is not made to have a gap, so that the binding force at the belt end is increased and the carcass is strengthened. Therefore, it is possible to achieve both the maintenance or improvement of durability in high-speed running and the improvement of road noise by reducing the cavity resonance.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The pneumatic radial tire 10 according to the present embodiment includes a carcass ply 12, a belt 14, and a belt reinforcing layer 16 in FIGS. 1 to 3.

  The carcass ply 12 is formed by straddling between a pair of bead portions 22 in a toroidal shape and winding back around the bead core 24 arranged on the bead portion from the inside to the outside. In this embodiment, at least one layer is provided. Has been.

  An end edge 12 </ b> A of the carcass ply 12 that is wound back by the bead core 24 is disposed between the carcass ply 12 and the belt 14 that are located in the crown portion 18. With this so-called envelope structure, even if the carcass ply 12 is a single layer, higher tire rigidity is ensured, and the weight is reduced as compared with a case where the carcass ply 12 has two layers.

The separation distance W ₁ between both end edges 12A is configured to be 50 to 80% of the width of the belt 14 closest to the carcass ply 12 in the cross section in the tire width direction.

If the separation distance W ₁ is less than 50% of the width of the belt 14, the central portion of the belt is difficult to deform, and cavity resonance inside the tire cannot be reduced, and if it exceeds 80%, the carcass ply 12 Since the meaning of disposing the end edge 12A between the carcass ply 12 and the belt 14 is reduced, rubber peeling at the belt end portion, the end edge 12A of the carcass ply 12 and the tread portion 26 is likely to occur. It is preferable to set it as 80 to 80%.

  The belt 14 is located radially outward of the carcass ply 12 and reinforces the tread portion 26, and is provided with at least one layer, in this embodiment, two layers.

  The belt reinforcing layer 16 is located outward in the radial direction of the belt 14, and a belt-shaped strip 16 </ b> A formed by rubber coating a plurality of cords has a gap in the vicinity of the end of the belt 14 in the tire width direction. Rather than being in the vicinity of the end, the gap 28 is spirally wound.

  Here, the absence of a gap means a state where the strip 16A is wound while being slightly overlapped, or a state where the strip 16A is not overlapped but is in contact with the adjacent strip 16A without a gap.

The belt reinforcing layer 16 may be wound in two layers in a range W ₂ in the tire width direction of 20 to 60 mm straddling the end portion in the vicinity of the end portion of the belt 14. This is because the binding force at the belt end portion is further increased and the high-speed durability is further improved.

When the range W _{2 for} winding the belt reinforcing layer 16 below 20 mm is less than 20 mm, the binding force at the belt end cannot be increased much more than the case of the single layer winding despite the fact that the belt is wound in two layers. In addition, if it exceeds 60 mm, the central portion of the belt becomes difficult to be deformed, and the cavity resonance inside the tire cannot be reduced. Therefore, the range is preferably 20 to 60 mm.

  The winding pitch P of the strip-shaped strip 16 </ b> A in the belt reinforcing layer 16 is, for example, 1.2 to 2 times the width of the strip 16 </ b> A except in the vicinity of the end of the belt 14.

  If the winding pitch is less than 1.2 times the width of the strip 16A, the central portion of the belt becomes difficult to be deformed, and cavity resonance inside the tire cannot be reduced. Since the reinforcement becomes insufficient, the range is preferably 1.2 to 2 times.

In addition, in this embodiment, as shown in FIG.1 and FIG.2, in order to cover and reinforce the both ends of the belt reinforcement layer 16 in the tire width direction, the 2nd belt reinforcement layer 30 is each arrange | positioned. In addition, in FIG. 3, illustration of this 2nd belt reinforcement layer is abbreviate | omitted.
(Test example)
Regarding road radial tires according to Conventional Example 1 to Conventional Example 4 and the pneumatic radial tire according to the present invention, which are composed of the carcass layer and the belt end portion reinforcing layer shown in Table 1, the road noise and the high-speed durability are as follows. A test was conducted. In addition, after manufacturing each tire, it was also inspected whether or not there is air accumulation at the belt end. These results are shown in Table 1. Conventional examples 1 to 4 correspond to the pneumatic radial tires 100, 200, 300, and 400 shown in FIGS. 4 to 7, respectively.

The tire size is 245 / 45ZR18.
(Test conditions and evaluation method for road noise)
The vehicle used is Celsior made by Toyota Motor Corporation, the tire internal pressure is 230 kPa, the general road input assumed road is used as the evaluation road, and the microphone mounted in the vehicle is used as the sound pressure measuring device, and the measurement is performed in the 250 Hz band. It was. As an evaluation method, the measured sound pressure was indexed by setting Conventional Example 1 as 100 and + 10% per -0.5 dB.

The reason why the measurement in the 250 Hz band is performed is that the cavity resonance sound, which is the resonance sound of the air inside the tire due to the deformation of the tire cross section, has a peak in the vicinity of 250 Hz.
(Test conditions and evaluation method for high-speed durability)
With a tire internal pressure of 230 kPa and an 8 kN load applied using a drum tester, the system runs at a constant speed for a predetermined time (20 minutes), and it cannot be used, such as bursting or peeling of the tread within that time. When it did not become a proper state, the traveling speed was increased by 10 km / h. The maximum traveling speed among the traveling speeds after a predetermined time was measured, and the traveling speed was indexed as + 10% per +10 km / h with the conventional example 1 being 100.

  According to this test example, it was confirmed that the road noise of the pneumatic radial tire according to the present invention was reduced by 4% compared to the conventional example 1. Moreover, about high-speed durability, it was confirmed that durability equivalent to the prior art example 1 is maintained.

  In the case of Conventional Example 3, the road noise and high-speed durability were the same as those of the pneumatic radial tire according to the present invention, but the tire of Conventional Example 3 had a manufacturing defect and was compared. Not suitable as a target.

  In Conventional Example 3, since there is no carcass at the center of the tread, the phenomenon that the upper end of the carcass ply is disengaged from the lower side of the belt end easily occurs when the tire is greatly deformed in the vulcanization process. This is likely to cause manufacturing defects.

1 is a cross-sectional view of a pneumatic radial tire according to the present invention. It is a partial expanded sectional view of the pneumatic radial tire concerning the present invention. It is a partial top view which shows the arrangement | positioning state of the carcass ply, the belt, and the belt reinforcement layer in the pneumatic radial tire which concerns on this invention. FIG. 6 is a cross-sectional view of a pneumatic radial tire according to a conventional example, including a two-layer carcass without hollows and a belt reinforcing layer without gap winding. FIG. 6 is a cross-sectional view of a pneumatic radial tire according to a conventional example, having a two-layer carcass that is hollowed out and a belt reinforcing layer without a gap winding. FIG. 6 is a cross-sectional view of a pneumatic radial tire according to a conventional example and having a separated carcass and a belt reinforcing layer without a gap winding. FIG. 6 is a cross-sectional view of a pneumatic radial tire according to a conventional example, including a two-layer carcass having no hollow and a belt reinforcing layer wound around a gap.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Pneumatic radial tire 12 Carcass ply 12A Edge 14 Belt 16 Belt reinforcement layer 16A Strip 18 Crown part 20 Side part 22 Bead part 24 Bead core 26 Tread part 28 Crevice

Claims (4)

At least one layer of a carcass ply that is wound between a pair of bead portions in a toroid shape and wound around the bead core from the inside to the outside around the bead core; and at least one layer of belt that is located radially outward of the carcass ply; In a pneumatic radial tire having a belt reinforcement layer located radially outward of the belt,
An end edge of the carcass ply rolled back by the bead core is disposed between the carcass ply and the belt located in the crown portion,
The separation distance between both the end edges is configured to be 50 to 80% of the width of the belt closest to the carcass ply in the cross section in the tire width direction.
The belt reinforcing layer is formed by spirally winding a strip-shaped strip with no gap in the vicinity of the end of the belt in the tire width direction and with no gap in the vicinity of the end,
Pneumatic radial tire characterized by. The belt reinforcing layer is wound in two layers over the entire range in the range of 20 to 60 mm in the tire width direction straddling the end portion in the vicinity of the end portion of the belt, and a range other than the vicinity of the end portion. So, it ’s one layer,
The pneumatic radial tire according to claim 1. The winding pitch of the strip-shaped strip in the belt reinforcing layer is 1.2 to 2 times the width of the strip except in the vicinity of the end of the belt,
The pneumatic radial tire according to claim 1 or 2, characterized in that.   The pneumatic radial tire according to any one of claims 1 to 3, wherein an aspect ratio is 70% or less.

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