JP2010089684A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire excellent in suppression of eccentric abrasion of a land part positioned at the innermost attachment side of a vehicle. <P>SOLUTION: A step-down rib 7 is only provided in a circumferential groove for forming a non-symmetric pattern on a tread part and positioned at the innermost side of the vehicle at attachment attitude to the vehicle given with a negative camber. A step-down amount H from an adjacent surface of the land part of the step-down rib 7 is in a range of 0≤H≤H<SB>0</SB>/4 relative to height H<SB>0</SB>of the land part, and width on a tread step surface satisfies a range of 2.0-20.0 mm. A clearance of the step-down rib 7 and the attachment inner shoulder land part 3 is narrower than a clearance of the step-down rib 7 and the land part adjacent to an inner side in a tire width direction of the shoulder land part, and the clearance L of the step-down rib 7 and the shoulder land part 3 satisfies a range of 0.5≤L≤2.0 mm. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire excellent in suppressing uneven wear inside a vehicle.

  For pneumatic tires, if uneven wear occurs on the shoulder land located inside the vehicle, it is difficult to see when attached to the vehicle and it is difficult for the driver to notice. The uneven wear progresses, and the carcass and the like are exposed to shorten the life of the tire. In the worst case, there is a possibility of causing a failure such as a tire burst.

  Therefore, for example, in order to suppress uneven wear of the shoulder land portion, in Patent Document 1, a step rib having a step is provided in one or both of the outermost circumferential grooves in the tread width direction, and the diameter of the step rib is adjacent. A means is disclosed in which a force in the braking direction is generated on the step rib during traveling by making it smaller than the periphery of the block, and the uneven wear is substituted for the step rib.

However, in the tire described in Patent Document 1, there is a possibility that uneven wear may occur in the shoulder land portion located most inside the wearing and wearing of the asymmetric pattern that has been increasing in recent years, and the technology for further reducing the uneven wear. Was desired.
US Patent Registration No. 5131444

  As a result of diligent investigations on this point, regarding the uneven wear of the shoulder land located on the innermost side of the vehicle, the setting of the vehicle was a negative camber, or it became a negative camber due to a change in load or a change over time while using the tire. In addition to being generated by using in a state, it has been found that the combination of toe-out setting and negative camber rapidly deteriorates.

  That is, under the negative camber condition, first, the negative camber causes the innermost shoulder land side wall of the vehicle to bulge or fall into the circumferential groove adjacent to the inner side in the tread width direction, This deformation causes bending deformation or squeezing deformation of the tread portion in the vicinity of the ground end, and the squeezing deformation in the vicinity of the ground end further causes shear deformation on the tread rubber in the ground end portion of the tread portion. This, and this shear deformation results in a camber thrust on the road surface, increasing the lateral force on the innermost shoulder land of the vehicle.

And secondly, in addition to this, at the time of negative camber, the innermost shoulder land part mounted on the vehicle strongly touches the road surface, and the innermost shoulder land part mounted on the vehicle tends to lift from the road surface conversely. In particular, in the innermost shoulder land portion of the vehicle, the amount of bulging tends to increase due to the strong grounding of the tread portion. A longitudinal force (braking force) opposite to the traveling direction is applied to the inner shoulder land portion.
It was found that these deformations occurred in the innermost shoulder land of the vehicle, causing uneven wear and progressing.

  Accordingly, an object of the present invention is to provide a pneumatic tire that is particularly excellent in suppressing uneven wear of a land portion located most inside the vehicle.

In the pneumatic tire according to the present invention, a plurality of circumferential grooves are provided on the tread surface, a land portion is defined between the outermost circumferential groove and the tread side edge, and an asymmetric pattern is formed on the tread portion. A negative camber is provided, and a step-down rib is provided only in a circumferential groove that is positioned most inside the vehicle when mounted on the vehicle, and adjacent to the step-down rib. stage down amount H from the land portion surface within a range of 0 ≦ _H ≦ H 0/4 with respect to the land portion height _{H 0,} the width at the tread surface satisfies the range of 2.0～20.0Mm, The interval between the step-down rib and the shoulder land portion that is located closest to the inside of the vehicle is narrower than the interval between the shoulder land portion and the land portion adjacent to the inner side in the tire width direction. The distance L from the part is 0.5 ≦ L ≦ 2.0 m And it is characterized in satisfying the range.

Here, the land height is an industrial standard effective in the area where tires are produced and used. In Japan, JATMA (Japan Automobile Tire Association) YEAR BOOK is used. In Europe, ETRTO (European Tire and Rim Technical Organization) is used. ) STANDARD MANUAL, in the United States TRA (THE TIRE and RIM ASSOCATION INC.) YEAR BOOK, etc., the tire is assembled, and the tire is filled with the highest air pressure defined by standards such as JATMA It shall be the distance measured from the bottom of the groove to the tread surface.
“A state in which a tire is mounted on an applicable rim, a specified air pressure is applied, and a load corresponding to a specified mass is applied” refers to a specified air pressure of a standard tire such as JATMA attached to an applicable rim. And a state where a load corresponding to the specified mass is applied.

  More preferably, in such a tire, the step-down rib is in contact with the road surface in a state where the tire is mounted on the applied rim, has a specified air pressure, and a load corresponding to a specified mass is applied.

［ｈ：Ｈ_０−Ｈ（段差がりリブの高さ），Ｅ：トレッドゴムのヤング率，ａ：段差がりリブの、トレッド踏面での幅，ｂ：段差リブの接地長］ Preferably, the rigidity G per unit length of the step-down rib in the tread width direction represented by the following formula satisfies a range of 1.0 to 30.0.

[H: H ₀ -H (height of the stepped rib), E: Young's modulus of the tread rubber, a: width of the stepped rib on the tread surface, b: contact length of the stepped rib]

  When the pneumatic tire of the present invention is mounted on a vehicle set as a negative camber, by providing a step-down rib only in the circumferential groove that will be positioned most inside the vehicle in the mounting posture to the vehicle, When this step-down rib rolls the tire, the wall surface of the shoulder land portion is deformed to suppress the bulge of the land portion that comes into contact with it, reducing the lateral force of the shoulder land portion, and bulging rubber Is supplied in the tire circumferential direction and acts in a direction that eliminates the deformation difference of the tread surface, so that the braking force of the shoulder land portion can be simultaneously reduced.

Further, in this stage down rib, step down amount H from the adjacent land portion surface within a range of ₀ ≦ H ≦ H _0/4 with respect to the land portion height H _0, the width a in the tread surface 2 By satisfying the range of 0.0 to 20.0 mm, the peripheral groove portion on the inner side of the vehicle mounting where the ground contact area is widened by the negative camber is reduced, and uneven wear of the shoulder land portion located on the innermost side of the vehicle mounting is suppressed. it can.

That is, when H is greater than H _0/4, can not effectively contact the sidewall of the shoulder land portion on the vehicle inner side, and is not able to expect little effect of suppressing the uneven wear initially, the shoulder land As the partial wear of the part progresses, the suppression effect tends to improve. On the other hand, when H is a negative value, the step-down rib protrudes from the surrounding land portion, and although there is little influence on the wearability, the rib may be damaged.

  Moreover, if the width a on the tread surface is less than 2.0 mm, the rigidity of the step-down rib in the tire width direction becomes low, and the swelling of the shoulder land portion cannot be suppressed, while it exceeds 20.0 mm. Then, the step-down ribs occupy most of the circumferential groove, and it is not possible to improve drainage.

  And the interval between the step-down rib and the shoulder land portion that is located most inside the vehicle is narrower than the interval between the land portion adjacent to the inside of the shoulder land portion in the tire width direction, and the step-down rib and the above-mentioned By satisfying the range of 0.5 ≦ L ≦ 2.0mm from the distance between the shoulder land and the shoulder land, the load on the tire, camber angle, tread pattern, and rubber properties change, and the hardness is proportional to the contact pressure. It is possible to suppress uneven wear caused by the amount of swelling of the shoulder land portion, which is in inverse proportion to the above.

  That is, when L is less than 0.5 mm, it is difficult to design a mold for molding a tire, and when L exceeds 2.0 mm, the step-down rib and the shoulder land portion come into contact with each other and the effect of suppressing bulging is achieved. Becomes smaller.

  By the way, if a similar step-down rib is provided on the outer side of the mounting, the influence of the inner force in the tread width direction during cornering is greater than the negative camber in this region, and the step-down rib suppresses the force on the outer side in the tread width direction. However, uneven wear may be deteriorated, and it is preferable to provide a stepped rib only on the inner side of the mounting from the viewpoint of ensuring drainage.

Hereinafter, the pneumatic tire of the present invention will be described in detail with reference to the drawings.
FIG. 1A is a partial development view of a tread pattern showing an embodiment of the pneumatic tire of the present invention, and FIG. 1B is an innermost view in the tread width direction in the tread pattern shown in FIG. It is a cross-sectional view of a cross section along the line bb of the circumferential groove.

The tread pattern shown in FIG. 1 is an asymmetrical pattern and is provided with a negative camber. In the figure, the left side is the inner side of the vehicle, 1 in the figure shows the entire tread surface, A plurality of circumferential grooves extending in the tread circumferential direction, in the figure, three circumferential grooves 2 are provided.
Each land portion is partitioned between two circumferential grooves 2 adjacent to each other and between the outermost circumferential groove and the tread side edge.

  The mounting inner shoulder land portion 3 located on the innermost mounting side of the vehicle is a rib, and each other land portion 4 is a block row in which a plurality of blocks 6 are partitioned by lateral grooves 5 extending in the tread width direction. To do.

  In the tread pattern shown in FIG. 1, the negative surface area is increased and the block surface area is increased with the aim of increasing the rigidity of each block 6 on the inner side of the tire with reference to the tire equator line and suppressing block deformation during cornering. On the other hand, the negative rate is increased on the outer side for the purpose of ensuring drainage when wet.

In this pneumatic tire, a step-down rib 7 is provided only in a circumferential groove that is located most inside the vehicle, particularly in the mounting posture on the vehicle, and from the surface of the adjacent land portion of the step-down rib 7. stage down amount H is within the range of the land portion height _{H 0} with respect to 0 ≦ H ≦ _H 0/4, satisfies the range width is 2.0~20.0mm at the tread surface, stepped down rib 7 And the inner shoulder land portion 3 is narrower than the land portion 4 adjacent to the inner side of the shoulder land portion 3 in the tire width direction, and the distance L between the step-down rib 7 and the shoulder land portion 3 is 0. It satisfies the range of 5 ≦ L ≦ 2.0 mm.
The distance L is preferably set to 2.0 mm or less for heavy duty tires and 1.0 mm or less for passenger military tires.

  By the way, the step-down rib 7 is not necessarily in contact with the road surface in a new tire, and as the shoulder land portion 3 is worn, the step-down rib 7 comes into contact with the road surface. By preferentially generating the braking force resulting from the above and substituting the stepped rib 7 for uneven wear, it is possible to suppress the uneven wear of the land portion from progressing inward in the tread width direction.

  More preferably, the step-down rib 7 is in contact with the road surface in a state where the tire is mounted on the applicable rim, the specified air pressure is applied, and a load corresponding to the specified mass is applied. It is dragged in the rotation direction, wear due to braking force can be developed, and a desired level difference can be maintained. Further, wear due to the driving force occurs around the step-down rib 7, and uneven wear can be suppressed.

［ｈ：Ｈ_０−Ｈ（段差がりリブの高さ），Ｅ：トレッドゴムのヤング率，ａ：段差がりリブの、トレッド踏面での幅，ｂ：段差リブの接地長］ Preferably, the rigidity G per unit length of the step-down rib 7 in the tread width direction represented by the following formula satisfies the range of 1.0 to 30.0.

[H: H ₀ -H (height of the stepped rib), E: Young's modulus of the tread rubber, a: width of the stepped rib on the tread surface, b: contact length of the stepped rib]

  By adopting this configuration, the step-down rib 7 can have rigidity for suppressing the bulging of the shoulder land portion 3.

  That is, if the rigidity G is less than 1.0, the rigidity in the tire width direction of the step-down rib 7 is low, and the swelling of the shoulder land portion cannot be suppressed, while the rigidity G exceeds 30.0. Then, the step-down rib 7 occupies most of the circumferential groove, and there is a tendency that improvement in drainage and the like cannot be expected.

  By setting the width a of the step-down rib to 4 mm or more for heavy-duty tires and 2 mm or more for passenger car tires, the bulging portion of the shoulder land portion can be effectively suppressed.

  Moreover, the groove width of the circumferential groove that is positioned most inside the vehicle can be in the range of 3.0 to 30.0 mm, and both drainage and wet wear on wet roads can be achieved.

  2A is a partial development view of a tread pattern showing a pneumatic tire according to another embodiment of the present invention, and FIG. 2B is an innermost side in the tread width direction in the tread pattern shown in FIG. It is sectional drawing which follows the bb line of the surrounding groove | channel.

The tread pattern shown in FIG. 2 is an asymmetrical pattern and is given a negative camber. In FIG. 2, the left side is the inside of the vehicle, and 11 in the figure shows the entire tread surface. 11 includes a plurality of circumferential grooves extending in the tread circumferential direction, two center circumferential grooves 12 provided with a tire equator line therebetween in the figure, and intermediate portions adjacent to the respective side portions of the center circumferential groove 12. A circumferential groove 13 and a shoulder circumferential groove 14 adjacent to the outer side in the tread width direction of each of the intermediate circumferential grooves 13 are disposed.
Between the two circumferential grooves adjacent to each other, in the figure, the central land portion 15 between the two center circumferential grooves 12, and the first intermediate land portion 16 between the center circumferential groove 12 and the intermediate circumferential groove 13, A second intermediate land portion 17 is defined between each intermediate circumferential groove 13 and the shoulder circumferential groove 14, and a shoulder land portion 18 is defined between the shoulder circumferential groove 14 and the tread side edge.

  In the central land portion 15, a plurality of central blocks 20 are defined by lateral grooves 19 that extend in the tread width direction and open to the respective center circumferential grooves 12 across the central land portion 15. In addition, the first intermediate land portion 16 includes an inclined groove that is inclined with respect to the tread circumferential direction and extends across the first intermediate land portion 16 and opens to each of the center circumferential groove 12 and the intermediate circumferential groove 13. A plurality of first intermediate blocks 22 are partitioned by 21.

  Further, in the second intermediate land portion 17in on the inner side of the vehicle, the lateral grooves 23 extending in the tread width direction and ending in the second intermediate land portion 17in from the intermediate peripheral groove 13 and the shoulder peripheral groove 14 respectively. In the second intermediate land portion 17out outside the vehicle, a plurality of second intermediate blocks 25 having a plurality of widths are defined by transverse grooves 24 that open to the circumferential grooves 13 and 14 in the second intermediate land portion 17out outside the vehicle. To do.

In this pneumatic tire, a step-down rib 26 is provided only in the shoulder circumferential groove 14 located on the innermost side of the vehicle when mounted on the vehicle, and the step-down rib 26 is stepped from the adjacent land surface. decreases the amount of H is in the range of 0 ≦ _H ≦ H 0/4 with respect to the land portion height _{H 0,} the width at the tread surface satisfies the range of 2.0～20.0Mm, stage down rib 26 and the shoulder The distance to the land portion 18 is narrower than the distance to the second intermediate land portion 17in, and the distance L between the step-down rib 26 and the shoulder land portion 18 satisfies the range of 0.5 ≦ L ≦ 2.0 mm.

Next, the tire of Example 225 of the tire of size 225 / 45R17 and the comparative example tires 1 to 3 were made as prototypes, and as shown in Table 1, the uneven wear properties in which the respective specifications were changed, evaluated. The comparative example tire 3 is provided with step-down ribs on the inside and outside of the vehicle.
In the comparative example tire, the other configurations are the same as in the example tire.

  For each of the Example tire 1 and Comparative tires 1 to 3, with a rim size of 7.5 J × 17 and a tire pressure of 230 kPa, the front wheel of the FR vehicle was mounted at a negative camber of 2 °, and the test course was run at a speed of 0 to 100 km / By running 1000 km at h, the difference in wear amount between the wearing inner shoulder land and the land located near the tire equator line was evaluated, and the results are shown in Table 2. The evaluation in Table 2 shows that the comparative example tire 1 has an index of 100, and the smaller the value, the smaller the difference in the amount of wear with the land located near the tire equator line.

  From the results shown in Table 2, the example tire 1 was superior in uneven wear resistance to the comparative example tires 1 to 3.

Next, Example tire 2 of a tire having a size of 435 / 45R22.5, and comparative tires 4 to 7 were manufactured as prototypes, and the other components were changed as shown in Table 3, and the uneven wear characteristics were changed. Was evaluated.
In the comparative example tire, the other configurations are the same as in the example tire.

  For each of the tire 2 and comparative tires 4 to 7, the rim size is 14.00 × 22.5 and the tire pressure is 900 kPa. It is in a state where the shaft is bent and becomes a negative camber due to axle loading, and by traveling 3000 km at a speed of 0 to 80 km / h, the innermost land portion mounted and the central land portion located near the tire equator line The difference in the amount of wear was evaluated, and the results are shown in Table 3. The evaluation in Table 3 shows that the comparative example tire 4 is index 100, and the smaller the value, the smaller the difference in the amount of wear with the central land portion.

  From the results of Table 4, Example Tire 2 was superior in uneven wear resistance to Comparative Example Tires 4-7.

(A) is the partial expanded view of the tread pattern which shows one Embodiment of the pneumatic tire of this invention, (b) is a fragmentary sectional view which shows some embodiment of a groove | channel. (A) is the partial expanded view of the tread pattern which shows other embodiment of the pneumatic tire of this invention, (b) is a fragmentary sectional view which shows some embodiment of a groove | channel. It is a partial expanded view of the tread pattern which shows embodiment of the conventional pneumatic tire. It is a partial expanded view of the tread pattern which shows embodiment of the conventional pneumatic tire. It is a partial expanded view of the tread pattern which shows embodiment of the conventional pneumatic tire. It is a partial expanded view of the tread pattern which shows embodiment of the conventional pneumatic tire. It is a partial expanded view of the tread pattern which shows embodiment of the conventional pneumatic tire. It is a partial expanded view of the tread pattern which shows embodiment of the conventional pneumatic tire. It is a partial expanded view of the tread pattern which shows embodiment of the conventional pneumatic tire.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tread tread 2 Circumferential groove 3 Mounted inner shoulder land 4 Land 5 Cross groove 6 Block 7 Step-down rib 11 Tread tread 12 Center circumferential groove 13 Intermediate circumferential groove 14 Shoulder circumferential groove 15 Central land 16 First intermediate land 17in vehicle Inner second intermediate land portion 17out Second outer land portion outside vehicle 18 Shoulder land portion 19, 23, 24 Horizontal groove 20 Central block 21 Inclined groove 22 First intermediate block 25 Second intermediate block 26 Step-down rib

Claims (3)

A plurality of circumferential grooves are arranged on the tread surface, a shoulder land is defined between the outermost circumferential groove and the tread side edge, an asymmetric pattern is formed on the tread, and a negative camber is applied. Pneumatic tires
In the mounting posture to the vehicle, a step-down rib is provided only in the circumferential groove that will be located most inside the vehicle,
This stage down rib, step down amount H from the adjacent land portion surface within a range of ₀ ≦ H ≦ H _0/4 with respect to the land portion height H _0, width a at the tread surface is 2.0 Satisfy the range of ~ 20.0mm,
The interval between the step-down rib and the shoulder land portion that is located closest to the inside of the vehicle is narrower than the interval between the shoulder land portion and the land portion adjacent to the inner side in the tire width direction. A pneumatic tire characterized in that the distance L between the portions satisfies a range of 0.5 ≦ L ≦ 2.0 mm.   2. The pneumatic tire according to claim 1, wherein the step-down rib contacts the road surface in a state where the tire is mounted on an applicable rim, has a specified air pressure, and a load corresponding to a specified mass is applied. The pneumatic tire according to claim 1 or 2, wherein rigidity G per unit length in the tread width direction represented by the following formula of the step-down rib satisfies a range of 1.0 to 30.0.

[H: H ₀ -H (height of the stepped rib), E: Young's modulus of the tread rubber, a: width of the stepped rib on the tread surface, b: contact length of the stepped rib]

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