JP2012116246A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve maneuvering stability, while maintaining partial abrasion resistant performance.SOLUTION: A pneumatic tire 1 includes a carcass 6, a belt layer 7 arranged outside the carcass 6, a band layer 9 having a band cord 12 arranged outside the belt layer 7 and arranged at an angle of 5 degrees or less to the tire circumferential direction, and tread rubber 2G arranged outside the band layer 9. The tread rubber 2G includes a high modulus part 10H arranged in a shoulder area and made of a rubber material having a large modulus, and a low modulus part 10L adjacent in the tread width direction to the high modulus part 10H and made of a rubber material smaller in a modulus than the high modulus part 10H. The band layer 9 includes a low density part 11L arranged inside the high modulus part 10H and small in arrangement density of the band cord 12, and a high density part 11H arranged inside the low modulus part 10L and larger in the arrangement density of the band cord 12 than the low density part 11L.

Description

  The present invention relates to a pneumatic tire that can improve steering stability while maintaining uneven wear resistance.

  There has been proposed a pneumatic tire using rubber materials having different moduli for the tread rubber disposed in the tread portion (for example, see Patent Document 1 below). In this type of pneumatic tire, a rubber material having a relatively large modulus is disposed in a shoulder region where the contact pressure tends to be high during turning, and a rubber material having a small modulus is disposed in a crown region. Such a pneumatic tire is expected to improve the uneven wear resistance performance of the tread rubber.

JP 2008-155722 A

  However, in the pneumatic tire as described above, the rubber modulus varies greatly between the crown region and the shoulder region. For this reason, for example, during turning, when the ground contact center of the tread portion shifts from the crown region to the shoulder region, a change in the generated lateral force or the like tends to be abrupt (non-linear). For this reason, in the above-described pneumatic tire, there has been a tendency that the behavior change of the vehicle is not stable and the steering stability is lowered.

  The present invention has been devised in view of the actual situation as described above. The tread rubber has a high modulus portion made of a rubber material having a large modulus, and the high modulus portion is adjacent to the high modulus portion in the tread width direction. A low modulus portion made of a rubber material having a smaller modulus than the low modulus portion, and the band layer includes a low density portion disposed on the inner side in the tire radial direction of the high modulus portion and a low band cord arrangement density, and a low modulus portion. The air that can improve the steering stability while maintaining the anti-wearing performance based on the fact that it is arranged on the inner side of the tire in the radial direction of the tire and includes a high density part in which the band cord arrangement density is larger than the low density part. The main purpose is to provide tires.

  The invention according to claim 1 of the present invention includes a carcass that extends from the tread portion through the sidewall portion to the bead core of the bead portion, a belt layer disposed on the outer side in the tire radial direction of the carcass and inward of the tread portion, A band layer having a band cord arranged outside the belt layer in the tire radial direction and arranged at an angle of 5 degrees or less with respect to the tire circumferential direction, and a tread rubber arranged outside the band layer and contacting the road surface The tread rubber is disposed in at least one shoulder region and is made of a rubber material having a large modulus, and the tread rubber is adjacent to the high modulus portion in the tread width direction and A low modulus portion made of a rubber material having a smaller modulus than that of the high modulus portion, and the band layer includes the high modulus portion. A low density portion disposed on the inner side in the tire radial direction and having a small band cord arrangement density, and a high density portion disposed on the inner side in the tire radial direction of the low modulus portion and having a band cord arrangement density larger than the low density portion; It is characterized by including.

  According to a second aspect of the present invention, the high modulus portion is disposed in shoulder regions on both sides, and the low modulus portion is disposed in a crown region between the shoulder regions and including the tire equator. This is a pneumatic tire.

  According to a third aspect of the present invention, the mounting direction of the vehicle is specified, and the high modulus portion is disposed outside the vehicle, while the low modulus portion is disposed inside the vehicle. It is a pneumatic tire.

  According to a fourth aspect of the present invention, a modulus ratio Rm, which is a ratio Ma / Mb between a modulus Ma of the high modulus portion and a modulus Mb of the low modulus portion, is 1.1 or more and 2.0 or less. The pneumatic tire according to any one of claims 1 to 3, wherein a width of the modulus portion in a tire axial direction is 20% or more of a tread contact width.

  According to a fifth aspect of the invention, the band code density ratio Rb, which is the ratio Ba / Bb between the band cord arrangement density Ba of the high density portion and the band cord arrangement density Bb of the low density portion, is 1.02. The pneumatic tire according to claim 4, which is 1.90 or less.

  The invention according to claim 6 is the pneumatic tire according to claim 5, wherein a ratio Rm / Rb between the modulus ratio Rm and the band cord density ratio Rb is 0.78 or more and 1.19 or less.

  Here, the tread contact width is a tread when a normal load is loaded on a normal rim that is assembled with a normal rim and filled with a normal internal pressure, and a normal load is applied to a flat surface with a camber angle of 0 degrees. The distance in the tire axial direction between the outermost ground contact ends of the part. Further, the dimensions and the like of each part of the tire are values in the normal state unless otherwise specified.

  The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based. For example, “Standard Rim” for JATMA and “Design Rim” for TRA. "If ETRTO," Measuring Rim ".

  Furthermore, “regular internal pressure” is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based. “JAMATA” is the “highest air pressure”, TRA is the table “TIRE LOAD” Maximum value described in “LIMITS AT VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” for ETRTO.

  In this specification, the “regular load” is a load determined by each standard for each tire in the standard system including the standard on which the tire is based. For example, the maximum value described in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES”, or “LOAD CAPACITY” for ETRTO. In addition, when neither standard exists, a tire manufacturer's recommendation value is applied.

In the present specification, “modulus” is a complex elastic modulus E measured using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho Co., Ltd. under the following conditions in accordance with the standard of “JIS-K6394”. *
Initial strain: 10%
Amplitude: ± 1%
Frequency: 10Hz
Deformation mode: Tensile measurement temperature: 70 ° C

  The pneumatic tire according to the present invention includes, as a tread rubber, a high modulus portion made of a rubber material that is disposed in at least one shoulder region and has a large modulus, and is disposed on the tire equator side from the high modulus portion, and the high modulus portion. And a low modulus portion made of a rubber material having a smaller modulus. Such a tread rubber can suppress wear in the shoulder region where the contact pressure is high, make the wear of the tread uniform, and improve uneven wear resistance.

  In addition, the band layer is arranged on the inner side in the tire radial direction of the high modulus portion and the arrangement density of the band cord is small, and on the inner side in the tire radial direction of the low modulus portion and the arrangement density of the band cord is low. A high density part larger than the density part is included. In such a pneumatic tire, the rigidity of the low modulus portion is increased by the high-density portion, so that the rigidity of the outer portion in the tire radial direction of the belt layer (composite of the tread rubber and the band layer) is uniform in the tread width direction. Get closer to. Therefore, it is possible to improve the steering stability by making the change in the lateral force and the like generated during the turn closer to linear and stabilizing the behavior change of the vehicle.

It is sectional drawing which shows the pneumatic tire of this embodiment. (A), (b) is the fragmentary sectional view of the tread part explaining the high-density part and low-density part of a band layer. It is sectional drawing which shows the pneumatic tire of other embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, a pneumatic tire (hereinafter sometimes simply referred to as “tire”) 1 of the present embodiment is a carcass that extends from a tread portion 2 to a side wall portion 3 to a bead core 5 of a bead portion 4. 6, a belt layer 7 disposed outside the carcass 6 in the tire radial direction and inside the tread portion 2, a band layer 9 disposed outside the belt layer 7 in the tire radial direction, and an outside of the band layer 9. It is comprised as a radial tire for passenger cars provided with the tread rubber 2G which is distribute | arranged and is grounded.

  The carcass 6 is composed of at least one carcass ply 6A, in this embodiment, one carcass ply 6A. The carcass ply 6A is folded back from the inner side to the outer side in the tire axial direction around the bead core 5 extending from the main body 6a and extending from the main body 6a to the bead core 5 of the bead part 4 through the sidewall part 3 and the bead part 4. And the folded portion 6b. Further, a bead apex 8 made of hard rubber extending from the bead core 5 to the outer side in the tire radial direction is disposed between the main body portion 6a and the folded portion 6b, and the bead portion 4 is appropriately reinforced.

  Further, the carcass ply 6A has carcass cords arranged at an angle of, for example, 80 to 90 degrees with respect to the tire equator C. As the carcass cord, for example, an organic fiber cord such as polyester, nylon, rayon, or aramid is suitably employed.

  The belt layer 7 includes at least two belt plies 7A, in which the belt cord is inclined with respect to the tire equator C at a small angle of, for example, 10 to 40 degrees, and in the present embodiment, the inner and outer two belt plies 7A, 7B is configured by superimposing the belt cords so that the belt cords cross each other. Steel cords are used for the belt cords of the present embodiment, but highly elastic organic fiber cords such as aramid and rayon can also be used as necessary.

  The tread rubber 2G includes a high modulus portion 10H made of a rubber material having a large modulus, and a low modulus portion 10L made of a rubber material adjacent to the high modulus portion 10H in the tread width direction and having a modulus smaller than that of the high modulus portion 10H. It is comprised including.

  In the present embodiment, the high modulus portion 10H is disposed in the shoulder regions Sh on both sides. On the other hand, the low modulus portion 10L is arranged in the crown region Cr between the shoulder regions Sh and including the tire equator C. In such a tread rubber 2G, since the high modulus portion 10H is disposed in the shoulder region Sh where the ground pressure is large and the wear energy tends to be large during turning, the shoulder region Sh is worn earlier than the crown region Cr. Uneven wear such as shoulder wear can be suppressed. In addition, since the low modulus portion 10L is arranged in the crown region Cr with relatively small wear energy, it is possible to balance the shoulder region Sh and wear, and to improve the riding comfort.

  The band layer 9 is constituted by a band ply 9A in which band cords 12 (shown in FIG. 2) are arranged at an angle of 5 degrees or less with respect to the tire circumferential direction. The band ply 9 </ b> A is formed of, for example, a full band ply that covers the entire width of the belt layer 7. As the band cord 12, for example, an organic fiber cord such as nylon, aramid, or PEN is preferably used.

  In addition, the band layer 9 of the present embodiment is formed of a low density portion 11L in which the arrangement density of the band cord 12 is small and a high density portion 11H in which the arrangement density of the band cord 12 is larger than the low density portion 11L. The low density portion 11L is disposed on the inner side in the tire radial direction of the high modulus portion 10H, and the high density portion 11H is disposed on the inner side in the tire radial direction of the low modulus portion 10L.

  In the combination of the band layer 9 and the tread rubber 2G as described above, the high-density portion 11H increases the rigidity of the low modulus portion 10L, so that the tread rubber 2G and the band layer 9 forming the outer portion in the tire radial direction of the belt layer 7 The rigidity of the composite 15 is made uniform in the tread width direction. That is, the difference in rigidity between the first composite 15A composed of the high density portion 11H and the low modulus portion 10L and the rigidity of the second composite 15B composed of the high modulus portion 10H and the low density portion 11L can be reduced. Therefore, the change in the behavior of the vehicle is stabilized by making the change in the lateral force or the like generated during the turn closer to linear. Thereby, as for the tire 1 of this embodiment, steering stability improves.

  In the present embodiment, the same tire cord (the same twist structure, material, and fineness) are used for the band cords 12 of the high density portion 11H and the low density portion 11L of the band layer 9. Therefore, the tire 1 of the present embodiment can achieve uniform rigidity in the tread width direction only by changing the arrangement density of the band cords 12, so that productivity and manufacturing cost are not deteriorated.

  As shown in FIG. 2A, the band layer 9 according to the present embodiment is, for example, a small piece in which a plurality of (for example, about 2 to 10) band cords 12 arranged in parallel are embedded in a topping rubber 13. The belt-like ply 14 having a width is formed as a jointless ply formed by spirally winding in the tire circumferential direction. The belt-like ply 14 may be one in which one band cord 12 is covered with a topping rubber 13. As shown in FIG. 2B, the belt-like plies 14 adjacent in the tire axial direction may be arranged such that the side edges 14t and 14t are separated from each other.

  The jointless ply can easily adjust the arrangement density by changing the helical pitch P, which is the distance between the same side edges 14t, 14t of the belt-like plies 14 adjacent in the tire axial direction. That is, the band-like ply 14 is spirally wound with a small helical pitch P, whereby the arrangement density of the band cords 12 of the jointless ply can be increased. Conversely, the band-like ply 14 is spirally wound with a large helical pitch P, whereby the arrangement density of the band cords 12 of the jointless ply can be reduced.

  Therefore, as shown in FIGS. 2A and 2B, in the present embodiment, the high density portion 11H has the band-like ply 14 with the helical pitch P1 relatively smaller than the helical pitch P2 of the low density portion 11L. It can be formed by being spirally wound. As described above, the band layer 9 can form the high density portion 11H and the low density portion 11L only by changing the spiral pitches P1 and P2 of the belt-like ply 14. Moreover, in the present embodiment, the low density portion 11L and the high density portion 11H can be formed in the process of continuously winding the belt-like ply 14 from the one tread end 2t side to the other tread end 2t side. Therefore, the pneumatic tire of this embodiment is produced at a low manufacturing cost.

  Here, it is desirable to regulate the modulus of the tread rubber 2G within a certain range. That is, the modulus ratio Rm, which is the ratio Ma / Mb between the modulus Ma of the high modulus portion 10H and the modulus Mb of the low modulus portion 10L, is preferably 1.1 or more, more preferably 1.15 or more, Preferably it is 2.0 or less, More preferably, 1.5 or less is desirable. If the modulus ratio Rm is less than 1.1, the modulus difference between the high modulus portion 10H and the low modulus portion 10L becomes small, and there is a risk that uniform wear of the tread portion 2 may not be obtained, and conversely exceeds 2.0. On the contrary, there is a possibility that the wear is concentrated on the low modulus portion 10L.

  In addition, the value of the modulus Ma of the rubber material of the high modulus portion 10H is not particularly limited, but if it is too small, the effect of suppressing the wear of the shoulder region Sh tends to decrease, and conversely if too large, There is a possibility that the rigidity of the high modulus portion 10H is excessively increased, and the steering stability and the ride comfort are deteriorated. From such a viewpoint, the modulus Ma of the high modulus portion 10H is preferably 3.5 MPa or more, more preferably 4.0 MPa or more, and preferably 13 MPa or less, more preferably 10 MPa or less.

  Further, the value of the modulus Mb of the low modulus portion 10L is not particularly limited, but if it is too small, there is a risk that uneven wear of the crown region Cr may occur early, and conversely if too large, There is a possibility that the wear may concentrate on the shoulder region Sh by approaching the modulus Ma of the high modulus portion 10H. From such a viewpoint, the modulus Mb of the rubber material of the low modulus portion 10L is preferably 2.5 MPa or more, more preferably 3.0 MPa or more, and preferably 12 MPa or less, more preferably 9.0 MPa or less. desirable.

  In the band layer 9 as well, it is desirable to regulate the arrangement density of the high density portions 11H and the low density portions 11L within a certain range. That is, as a result of various experiments conducted by the inventors, in order to make the rigidity of the composite 15 outside the belt layer 7 uniform in the tread width direction, assuming the range of the modulus ratio Rm of the tread rubber. The band code density ratio Rb, which is the ratio Ba / Bb between the arrangement density Ba of the high density portion 11H of the band layer 9 and the arrangement density Bb of the low density portion 11L, is preferably 1.02 or more, more preferably 1. It has been found that it is effective to be 05 or more, and preferably 1.90 or less, more preferably 1.70 or less.

  Here, the arrangement densities Ba and Bb of the high density portion 11H and the low density portion 11L are each represented by the number of band codes included per 1 cm width measured along the band ply.

  Further, the value of the arrangement density Ba of the band cord 12 of the high-density portion 11H is not particularly limited, but if it is too small, the reinforcing effect of the low modulus portion 10L is reduced, and the rigidity of the composite 15 is reduced. There is a possibility that it cannot be made uniform in the tread width direction, and conversely, if it is too large, the rigidity of the first composite 15A may be excessively increased. From such a viewpoint, the arrangement density Ba of the high-density portion 11H is preferably 5.0 (lines / cm) or more, more preferably 5.6 (lines / cm) or more, and preferably 30 (lines / cm). / Cm) or less, more preferably 25 (lines / cm) or less.

  From the same viewpoint, the arrangement density Bb of the band code 12 of the low density portion 11L is preferably 3.9 (lines / cm) or more, more preferably 4.5 (lines / cm) or more, and preferably Is 36 (lines / cm) or less, more preferably 28.5 (lines / cm) or less.

  Further, a ratio Rm / Rb between the modulus ratio Rm of the tread rubber 2G and the band cord density ratio Rb of the band layer 9, that is, (modulus Ma of high modulus portion 10H × array density Bb of low density portion 11L) / The (modulus Mb of the low modulus portion 10L × the arrangement density Ba of the high density portion 11H) can also be set as appropriate, but if it is too small, the rigidity of the second composite 15B may be excessively reduced and uneven wear may occur. is there. On the other hand, if the ratio Rm / Rb is too large, the rigidity of the second composite 15B is excessively increased, and the steering stability may be reduced. From such a viewpoint, the ratio Rm / Rb between the modulus ratio Rm and the band cord density ratio Rb is preferably 0.78 or more, more preferably 0.83 or more, and preferably 1.19 or less. More preferably, 1.14 or less is desirable.

  When the tread rubber 2G includes the low modulus portion 10L of the crown region Cr and a pair of high modulus portions 10H arranged on both sides thereof as in the present embodiment, the tire axial direction of the high modulus portion 10H The width W2 is preferably 20% or more of the tread ground contact width TW, more preferably 25% or more. If the width W2 is too small, the uneven wear of the shoulder region Sh may not be sufficiently suppressed. On the other hand, if the width W2 of the high modulus portion 10H is too large, the rigidity of the crown region Cr is increased, and the ride comfort may be significantly deteriorated, and the wear of the tread portion 2 may not be made uniform. . From this point of view, the width W2 is preferably 40% or less, more preferably 35% or less of the tread ground contact width TW. The width W3 of the low modulus portion 10L in the tire axial direction is a remaining region of the high modulus portion 10H.

FIG. 3 shows a tire 1 according to another embodiment of the present invention.
The tire 1 has a tread pattern (not shown) in which the mounting direction to the vehicle is designated, and the mounting direction is displayed on the sidewall portion 3 of the tire 1 or the like. In the tread portion 2 of the present embodiment, the high modulus portion 10H is disposed in the region outside the vehicle from the tire equator C, while the low modulus portion 10L is disposed in the region inside the vehicle from the tire equator C. . That is, a rubber boundary having a different modulus is on the tire equator C. In such a tire 1, the high modulus portion 10 </ b> H is disposed in a sufficiently wide region on the vehicle outer side where the ground pressure during turning is relatively large, and the low modulus portion 10 </ b> L is disposed on the vehicle inner side where the ground pressure is relatively small. Therefore, it is possible to more effectively achieve uniform wear on the tread portion 2.

  In this embodiment, the boundary between the high modulus portion 10H and the low modulus portion 10L is located on the tire equator C, but the present invention is not limited to this. For example, when mounted on an automobile having a negative camber suspension, the high modulus portion 10H may extend further to the vehicle inner side than the tire equator C depending on the ground contact position of the tread portion 2.

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect. For example, the band layer 9 is a jointless ply formed by spirally winding the band-like ply 14. However, the band layer 9 is not limited to such a mode and may be a spliced wide ply. Needless to say.

Pneumatic tires with tread rubber and band layers specified in Table 1 were manufactured and their performance was tested. The common specifications are as follows.
Tire size: 225 / 45R17
Rim size: 17 × 7.5J
Tread contact width TW: 180mm
Band-ply width W1: 10.5mm
Band cord cord material: Nylon Band cord structure: 1400dtex / 2
The test method is as follows.

<Uneven wear resistance>
Each sample tire was assembled on the rim, filled with 210 kPa of internal pressure, mounted on all wheels of a 2000 cc domestic FR car, and after a total of 24 km of the circuit course on the dry asphalt road surface (limit travel), The presence or absence of uneven wear in the tread portion was visually observed. The evaluation is an index with Comparative Example 1 being 100, and the larger the value, the better.

<Steering stability>
With the above vehicle, the behavior when turning on the circuit course was evaluated by the feeling of the driver. The evaluation is an index with Comparative Example 1 being 100, and the larger the value, the better.

<Limited driving performance>
With the above vehicle, the grip stability and how the driving force is transmitted when turning on the circuit course (marginal driving) was evaluated based on the driver's sensuality. The evaluation was expressed as an index with Comparative Example 1 as 100. The larger the value, the better.
The test results are shown in Table 1.

  As a result of the test, it was confirmed that the pneumatic tires of the examples could improve steering stability while maintaining uneven wear resistance performance.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 2G Tread rubber 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 7 Belt layer 9 Band layer 10H High modulus part 10L Low modulus part 11H High density part 11L Low density part 12 Band cord

Claims (6)

A carcass from the tread part through the sidewall part to the bead core of the bead part,
A belt layer disposed radially outside the carcass and inside the tread,
A band layer having a band cord disposed outside the belt layer in the tire radial direction and arranged at an angle of 5 degrees or less with respect to the tire circumferential direction;
A pneumatic tire provided on the outside of the band layer and provided with a tread rubber that contacts the road surface,
The tread rubber is arranged in at least one shoulder region and has a high modulus portion made of a rubber material having a large modulus;
A low modulus portion made of a rubber material adjacent to the high modulus portion in the tread width direction and having a modulus smaller than that of the high modulus portion,
The band layer is disposed on the inner side in the tire radial direction of the high modulus portion, and a low density portion having a small arrangement density of band cords,
A pneumatic tire comprising: a high-density portion that is arranged on the inner side in the tire radial direction of the low modulus portion and has a band cord arrangement density larger than the low-density portion.   2. The pneumatic tire according to claim 1, wherein the high modulus portion is disposed in shoulder regions on both sides, and the low modulus portion is disposed in a crown region between the shoulder regions and including the tire equator.   2. The pneumatic tire according to claim 1, wherein an orientation of mounting on a vehicle is specified, and the high modulus portion is disposed on an outer side of the vehicle, while the low modulus portion is disposed on an inner side of the vehicle. A modulus ratio Rm, which is a ratio Ma / Mb between the modulus Ma of the high modulus portion and the modulus Mb of the low modulus portion, is 1.1 or more and 2.0 or less;
The pneumatic tire according to any one of claims 1 to 3, wherein a width of the high modulus portion in a tire axial direction is 20% or more of a tread contact width.   The band code density ratio Rb, which is the ratio Ba / Bb between the band cord arrangement density Ba of the high density portion and the band cord arrangement density Bb of the low density portion, is 1.02 or more and 1.90 or less. 4. The pneumatic tire according to 4.   The pneumatic tire according to claim 5, wherein a ratio Rm / Rb between the modulus ratio Rm and the band cord density ratio Rb is 0.78 or more and 1.19 or less.

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