JP5827381B2 - tire - Google Patents

Description

  The present invention relates to a tire in which a plurality of narrow grooves extending along a tread width direction are formed in a buttress portion.

  2. Description of the Related Art Conventionally, various methods for suppressing uneven wear of shoulder ribs formed on a tread shoulder portion have been used for heavy load tires mounted on vehicles such as trucks and buses.

  That is, the outer end of the shoulder rib in the tread width direction, which generally has a high contact pressure, has a greater amount of wear due to the lateral force associated with the turning of the vehicle than the inner end of the shoulder rib in the tread width direction. For this reason, the outer end in the tread width direction tends to be different from the outer diameter of the inner end in the tread width direction as the tire is used, and the shoulder ribs are uneven due to self-excited wear due to the growth of the generated friction nuclei. There is a problem that wear tends to progress. Self-excited wear occurs when tires having different outer diameters at the tread center portion and the tread shoulder portion roll while contacting the road surface. That is, the tread shoulder portion having a small outer diameter has a shorter circumference than the center portion of the tread, so that the tread shoulder portion slides and wears toward the traveling direction of the vehicle on the tire kicking side.

  Thus, for example, a tire is known in which a plurality of narrow grooves (sipes) are formed in a buttress portion that is formed between a tread and a sidewall and continues to a side end of the tread (for example, Patent Document 1).

  According to such a tire, the buttress portion is flexibly deformed, and the rigidity of the tread shoulder portion is reduced. For this reason, the uneven wear of the shoulder rib resulting from the outer diameter difference between the tread central portion and the tread shoulder portion is suppressed.

Japanese Unexamined Patent Publication No. 7-17213 (page 3, FIG. 1)

  However, the conventional tire described above has the following problems. That is, according to a tire having a plurality of narrow grooves formed in the buttress portion, although there is a certain effect on suppressing uneven wear of the shoulder ribs, a recess in which a friction core grows still occurs at the bottom of the narrow grooves. Or heel and toe wear on the shoulder ribs.

  Accordingly, an object of the present invention is to provide a tire that can more effectively suppress uneven wear of shoulder ribs when a plurality of narrow grooves are formed in a buttress portion.

In order to solve the above-described problems, the present invention has the following features. First, the first feature of the present invention is that a carcass (carcass 2) is provided on the outer side in the tire radial direction, and a belt layer (belt layer 4) for reinforcing the carcass, a tread (tread 6), and a sidewall (sidewall 14) A plurality of narrow grooves (for example, narrow grooves) that extend along the tread width direction (tread width direction W _TR ). 20) is a tire (pneumatic tire 1) formed in the buttress portion, and the narrow groove is inclined with respect to the tire normal along the tire radial direction in the tire side view, and the tread width In the cross section of the tire along the tire direction and the tire radial direction, the belt layer extends from the inner end in the tire radial direction of the belt layer and is perpendicular to the tire equator line (tire equator line CL). A narrow groove is formed between the line (straight line L1) and the surface of the tread, and the narrow groove is a first buttress portion (buttress portion 10) continuous with one side end of the tread and a second groove continuous with the other side end of the tread. An inclination angle (inclination angle θ ₂₀ ) formed in the buttress portion (buttress portion 12) and formed by the narrow groove formed in the first buttress portion and the tire normal line, and a narrow groove formed in the second buttress portion is the tire. The gist is that it is different from the inclination angle (inclination angle θ ₂₂ ) formed with the normal.

  According to such a tire, the narrow groove is inclined with respect to the tire normal along the tire radial direction in the tire sidewall view, so that the block portion is on the tire kick-out side in the tire circumferential direction. It becomes easy to deform into a convex bow.

  In other words, since the block portion can be prevented from slipping and wearing toward the traveling direction of the vehicle on the tire kick-out side, the tire can more effectively suppress uneven wear of the shoulder rib.

  Further, since the narrow groove is formed between a straight line orthogonal to the tire equator line and the surface of the tread, when the tire contacts the road surface, the narrow groove opens and contacts the tire circumferential direction. For this reason, the contact pressure of the shoulder rib is appropriately reduced, and the amount of wear due to the lateral force accompanying the turning of the vehicle can be reduced. Therefore, the tire suppresses a difference in outer diameter between the outer end in the tread width direction and the inner end in the tread width due to the use of the tire, and further develops uneven wear of the shoulder rib due to self-excited wear. Can be suppressed.

  The second feature of the present invention relates to the first feature of the present invention, wherein the narrow groove is linear in the side wall view, and the upper end portion (upper end portion 20a) of the narrow groove is in the side wall view. The gist of the present invention is that it is located on the opposite side of the tire in the rotational direction from the lower end (lower end 20b) of the narrow groove.

The third feature of the present invention relates to the second feature of the present invention, and the inclination angle (for example, the inclination angle θ ₂₀ ) formed by the narrow groove with the tire normal in the side wall view is 2 degrees to 10 degrees. It is a summary.

  A fourth feature of the present invention relates to any one of the first to third features of the present invention, and is a tire circumferential direction of a block portion (block portion 30) that is partitioned by narrow grooves and formed between the narrow grooves. The circumferential length L (circumferential length L30) along the radial direction and the radial length D (radial length D30) along the tire radial direction of the block portion have a relationship of L / D ≦ 1.0. The main point is to satisfy

  A fifth feature of the present invention relates to any one of the first to third features of the present invention, wherein the groove depth along the tire radial direction of the narrow groove is larger than the interval between adjacent narrow grooves. The gist.

  A sixth feature of the present invention relates to any one of the first to third features of the present invention, and the groove width (groove width W20) of the narrow groove along the tire circumferential direction is 0.3 mm to 1.0 mm. It is a summary.

  A seventh feature of the present invention relates to any one of the first to sixth features of the present invention, and the upper end portion of the narrow groove is located on the inner side in the tire radial direction from the surface of the tread in the side wall view. This is the gist.

  According to the characteristics of the present invention, it is possible to provide a tire that can more effectively suppress uneven wear of the shoulder ribs when a plurality of narrow grooves are formed in the buttress portion.

1 is a perspective view including a cross section in a tread width direction of a pneumatic tire 1 according to an embodiment of the present invention. 1 is a cross section along a tread width direction and a tire radial direction of a pneumatic tire 1 according to an embodiment of the present invention. It is a side wall surface view by the side of the buttress part 10 in the pneumatic tire 1 which concerns on embodiment of this invention. 1 is a perspective view including a cross section in a tread width direction of a narrow groove 20 in a pneumatic tire 1 according to an embodiment of the present invention. It is a side wall surface view by the buttress part 12 side in the pneumatic tire 1 which concerns on embodiment of this invention. It is the schematic diagram which showed the deformation | transformation of the block part 30 in the pneumatic tire 1 which concerns on embodiment of this invention. It is the schematic diagram which showed the deformation | transformation of the block part 30 in the pneumatic tire 1 which concerns on embodiment of this invention.

  Next, embodiments according to the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones.

  Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

[Embodiment]
In this embodiment, (1) tire configuration, (2) detailed configuration of narrow groove, (3) deformation of block part, (4) comparative evaluation, (5) action and effect, (6) other embodiments Will be described.

(1) Configuration of Tire FIG. 1 is a perspective view including a cross section in the tread width direction of a pneumatic tire 1 in an embodiment of the present invention. Each part which comprises the pneumatic tire 1 is demonstrated.

  Specifically, (1.1) carcass, (1.2) belt layer, (1.3) tread, and (1.4) buttress portion will be described.

(1.1) Carcass The pneumatic tire 1 includes a carcass 2 made of a carcass cord and rubber and forming a skeleton of the pneumatic tire 1.

  In the vicinity of the top of the carcass 2, a belt layer 4 formed in a belt shape along the tire circumferential direction R is formed.

(1.2) Belt layer
The belt layer 4 is provided outside the carcass 2 in the tire radial direction and reinforces the carcass 2. The belt layer 4 includes a first belt layer 4a coupled on the carcass 2 and a second belt layer 4b disposed on the outer side in the tire radial direction of the first belt layer 4a.

(1.3) Tread The pneumatic tire 1 includes a tread 6 that is grounded to the road surface during traveling. The tread 6, main grooves 8 extending continuously in the tire circumferential direction R are formed at predetermined intervals in the tread width direction W _TR.

(1.4) Buttress part
The pneumatic tire 1 includes a buttress portion that is formed between the tread 6 and the sidewall 14 and continues to the side end of the tread 6. Specifically, the pneumatic tire 1 includes a pair of buttress portions 10 and the buttress portion 12 on both sides of the tread width direction W _TR of the tread 6.

Specifically, the buttress portion 10, the tread 6, connected to the side edge of the vehicle outside of the tread width direction W _TR (OUT side).

Buttress portion 12, the tread 6, connected to the side edge of the vehicle inside of the tread width direction W _TR (IN side).

(1.5) Narrow groove
The pneumatic tire 1 includes a plurality of narrow grooves extending along the tread width direction in the buttress portion. Specifically, the pneumatic tire 1 includes a plurality of narrow grooves 20 that extend along the tread width direction W _TR in the buttress portion 10, and a plurality of narrow grooves 22 that extend along the tread width direction W _TR in the buttress portion 12. Is provided.

(2) Detailed structure of narrow groove The detailed structure of the narrow groove formed in the buttress part is demonstrated. Specifically, the detailed configuration of (2.1) narrow groove 20 and (2.2) narrow groove 22 will be described with reference to FIGS.

FIG. 2 is a cross section of the pneumatic tire 1 along the tread width direction _WTR and the tire radial direction. FIG. 3 is a side wall view of the buttress portion 10 side of the pneumatic tire 1. FIG. 4 is a perspective view including a cross section of the narrow groove 20 along the tire radial direction. FIG. 5 is a side wall view of the buttress portion 12 side of the pneumatic tire 1.

(2.1) Narrow groove 20
As shown in FIG. 2, the narrow groove 20 extends from the inner end in the tire radial direction of the belt layer 4 and is orthogonal to the tire equator line CL in the cross section of the pneumatic tire 1 along the tread width direction _WTR and the tire radial direction. Formed between the straight line L <b> 1 and the surface of the tread 6.

  As shown in FIG. 3, the narrow groove 20 is inclined with respect to the tire normal N along the tire radial direction in the side wall view of the pneumatic tire 1.

Specifically, the narrow groove 20 is linear when viewed from the side wall, and the upper end 20a of the narrow groove 20 is closer to the tire rotation direction than the lower end 20b of the narrow groove 20 when viewed from the side wall. It is located on the opposite side of (tire circumferential direction R side). The upper end portion 20a is an end portion on the outer side in the tire radial direction of the narrow groove 20 in the side wall view, and the lower end portion 20b is an end on the inner side in the tire radial direction of the narrow groove 20 in the side wall view. Part. In the side wall view, the inclination angle θ ₂₀ formed by the narrow groove 20 with the tire normal N is 2 ° to 10 °.

  The circumferential length L30 along the tire circumferential direction of the block portion 30 that is partitioned by the narrow grooves 20 and formed between the narrow grooves 20, and the radial length D30 along the tire radial direction of the block portion 30 are , L30 / D30 ≦ 1.0 is satisfied.

  The groove depth along the tire radial direction of the narrow grooves 20 is larger than the interval between the adjacent narrow grooves 20. Here, the groove depth indicates the radial length D30, and the interval between the adjacent narrow grooves 20 indicates the circumferential length L30.

  The groove width W20 of the narrow groove 20 along the tire circumferential direction is 0.3 mm to 1.0 mm.

  The upper end 20a of the narrow groove 20 is located on the inner side in the tire radial direction from the surface of the tread 6 in the side wall view. Specifically, the distance t from the surface of the tread 6 to the upper end 20a is 0 mm or more and 5 mm or less. The distance t is preferably 2 mm or less, and the optimum value is 0 mm.

The lower end 20b of the narrow groove 20 is located within a range of ± 5 mm in the tire radial direction with respect to the straight line L1 in the cross section of the pneumatic tire 1 along the tread width direction _WTR and the tire radial direction.

As shown in FIG. 4, the narrow groove 20 is formed in a quadrangular prism shape in which an upper surface including the upper end portion 20a and a lower surface including the lower end portion 20b are parallel. The surface facing the buttress portion 10 forming the narrow groove 20 is formed perpendicular to the upper surface and the lower surface.
(2.2) Narrow groove 22
As shown in FIG. 5, the narrow groove 22 is inclined with respect to the tire normal N along the tire radial direction in the side wall view of the pneumatic tire 1. Hereinafter, since the narrow groove 22 has the same characteristics as the narrow groove 20, detailed description thereof is omitted.

  The narrow groove 20 is formed in the buttress portion 10 continuous with one side end of the tread 6, and the narrow groove 22 is formed in the buttress portion 12 continuous with the other side end of the buttress portion 10.

The inclination angle θ ₂₀ formed by the narrow groove 20 formed in the buttress portion 10 and the tire normal N is different from the inclination angle θ ₂₂ formed by the fine groove 22 formed in the buttress portion 12 and the tire normal N.

(3) Deformation of block part Specifically, (3.1) When rolling while touching the road surface, (3.2) When sliding along the traveling direction occurs, FIG. I will explain. FIG. 6 is a schematic view showing a deformation of the block portion 30 when rolling while contacting the road surface in the cross section of the pneumatic tire 1 along the tire circumferential direction and the tire radial direction. FIG. 7 is a schematic diagram showing a deformation of the block portion 30 when the traveling direction slip occurs in the cross section of the pneumatic tire 1 along the tire circumferential direction and the tire radial direction.

(3.1) When rolling while being in contact with the road surface As shown in FIG. 6, when rolling while being in contact with the road surface, the block portion 30 has a deflection in the tire radial direction and an area in contact with the road surface G. The tire is compressed in the tire circumferential direction R due to the difference in displacement between the tread 6 and the belt layer 4. Specifically, the block portion 30 is deformed into a convex arcuate shape in the tire circumferential direction R on the tire kick-out side.

(3.2) When slipping along the traveling direction occurs As shown in FIG. 7, when slipping along the traveling direction occurs, the block portion 30 is in the tire circumferential direction R on the tire kicking side. On the other hand, it deforms into a convex arch shape in the opposite direction. As a result, a shearing force in the direction opposite to the traveling direction is generated on the tire kicking side, so that the block portion 30 slides and wears toward the traveling direction of the vehicle.

  Therefore, suppression of deformation into a convex arcuate shape in the opposite direction with respect to the tire circumferential direction R is effective in suppressing wear (self-excited wear) due to slippage along the traveling direction.

(4) Comparative Evaluation Next, in order to further clarify the effect of the present invention, comparative evaluation performed using pneumatic tires according to the following comparative examples and examples will be described. Specifically, (4.1) Evaluation method and (4.2) Evaluation result will be described. In addition, this invention is not limited at all by these examples.

(4.1) Evaluation method Uneven wear was evaluated using seven types of pneumatic tires. Data on pneumatic tires were measured under the following conditions.

・ Rim wheel size: 22.5 × 9.00
・ Internal pressure: 825 kPa
-Vehicle type: Rear wheel biaxial drive vehicle-Mounting position: Front wheel-Load condition: 3750kgf
Measurement method: Travels 100,000 km between 0 and 80 km, and measures the amount of wear between the shoulder rib tread width direction inner end and the shoulder rib tread width direction outer end. The amount of wear was measured for both the left and right wheels.

The configuration of each pneumatic tire will be described with reference to Table 1.

  The inclination angle θ shown in Table 1 is an angle formed by the narrow groove with the tire normal N in the side wall view. The inclination angle θ is such that the upper end portion of the narrow groove (end portion on the outer side in the tire radial direction) is closer to the tire circumferential direction R side of the tire than the lower end portion (end portion on the inner side in the tire radial direction) of the narrow groove in the side wall view. Indicates a negative angle.

  The groove width W is the width of the narrow groove in the side wall view. The circumferential length L is a length along the tire circumferential direction of the block portion that is partitioned by the narrow grooves and formed between the narrow grooves in the side wall view.

  The pneumatic tire of Comparative Example 1 has a different inclination angle θ compared to the pneumatic tire 1 shown in the embodiment. Specifically, the narrow groove of the pneumatic tire of Comparative Example 1 is formed along the tire normal N in the side wall view.

  The pneumatic tires of Examples 1 to 4 differ from the pneumatic tire of Comparative Example 1 only in the conditions in Table 1. In the pneumatic tire of Example 5, the upper end portion of the narrow groove is more radially inward than the tread surface in the side wall view as compared with Comparative Example 1 and the pneumatic tires of Examples 1 to 4. It is different in that it is located in In the pneumatic tires of Comparative Example 1 and Examples 1 to 4, the distance from the upper end of the narrow groove to the surface of the tread is 0 mm. That is, the upper ends of the narrow grooves of Comparative Example 1 and Examples 1 to 4 are exposed on the surface of the tread.

(4.2) Evaluation Results The evaluation results of each pneumatic tire will be described with reference to Table 2.

  The evaluation result of uneven wear was displayed as a contrast index when the evaluation result of the pneumatic tire according to Comparative Example 1 which is a conventional pneumatic tire is 100. The evaluation result of uneven wear shows that the smaller the value, the better the performance.

  It can be seen that the pneumatic tires according to Examples 1 to 5 can suppress uneven wear as compared with the pneumatic tire according to Comparative Example 1 when the inclination angle θ is positive.

(5) Action / Effect As described above, according to the pneumatic tire 1 according to the present embodiment, the narrow groove 20 is the tire normal along the tire radial direction in the side view of the pneumatic tire 1. Since the block portion 30 is inclined with respect to N, the block portion 30 is easily deformed into a convex arcuate shape in the tire circumferential direction R on the tire kick-out side.

  In other words, since the block portion 30 can be prevented from slipping and wearing toward the traveling direction of the vehicle on the tire kick-out side, the pneumatic tire 1 can further effectively suppress uneven wear of the shoulder rib.

  Further, since the narrow groove 20 is formed between the straight line L1 and the surface of the tread 6, when the pneumatic tire 1 contacts with the road surface G, the narrow groove 20 extends along the tire circumferential direction R. Open and ground.

  For this reason, the contact pressure of the shoulder rib is appropriately reduced, and the amount of wear due to the lateral force accompanying the turning of the vehicle can be reduced. Therefore, the pneumatic tire 1 suppresses a difference in outer diameter between the outer end in the tread width direction and the inner end in the tread width accompanying use of the tire, and uneven wear of the shoulder ribs due to self-excited wear develops. This can be further suppressed.

  In the present embodiment, the narrow groove 20 is linear when viewed from the side wall, and the upper end 20a is located on the opposite side of the tire rotation direction from the lower end 20b. The shape of the narrow groove 20 is close to the shape of the block portion 30 because it deforms due to the deflection in the tire radial direction and the difference in displacement between the tread 6 and the belt layer 4 on the tire kick-out side in the side wall view. .

  Accordingly, the block 30 is more easily deformed into a convex arc shape in the tire circumferential direction R on the tire kicking side, so that the pneumatic tire 1 can further suppress uneven wear of the shoulder rib.

In the present embodiment, the inclination angle θ ₂₀ formed between the narrow groove 20 and the tire normal N is 2 degrees to 10 degrees in the side wall view, so the shape of the narrow groove 20 is the tire in the side wall view. On the kicking side, the shape of the block portion 30 is further closer due to the deflection in the tire radial direction and the difference in displacement between the tread 6 and the belt layer 4.

In the present embodiment, the tilt angle theta ₂₀ small grooves 20 formed on the buttress portion 10 makes with the tire normal line N, narrow groove 22 formed buttress portion 12 and the inclination angle theta ₂₂ formed between the tire normal line N Is different.

Accordingly, for example, the buttress portion 10 connected to the outer end in the tread width direction of the shoulder rib having a high contact pressure is used as the buttress portion 10 and the inclination angle θ ₂₀ is set to 2 degrees to 10 degrees to suppress the development of uneven wear. At the same time, the difference in the amount of wear that occurs between the buttress portion 10 and the buttress portion 12 can be reduced.

  In the present embodiment, since the relationship of L30 / D30 ≦ 1.0 is satisfied, the block portion 30 is further easily deformed into a convex arcuate shape in the tire circumferential direction R on the tire kicking side.

  In the present embodiment, since the groove depth along the tire radial direction of the narrow groove 20 is larger than the interval between the adjacent narrow grooves 20, the block portion 30 protrudes in the tire circumferential direction R on the tire kicking side. It becomes easier to deform into a bow shape.

  Furthermore, the groove width W20 of the narrow groove 20 along the tire circumferential direction is 0.3 mm to 1.0 mm, so that when the pneumatic tire 1 contacts the road surface G, the narrow groove 20 It opens along the direction R to facilitate grounding.

  In the present embodiment, since the upper end portion 20a is located on the inner side in the tire radial direction from the surface of the tread 6 in the side wall view, for example, when uneven wear occurs in the pneumatic tire 1, the upper end portion 20a is By exposing, the uneven wear of the shoulder rib can be effectively suppressed.

(6) Other Embodiments As described above, the contents of the present invention have been disclosed through the embodiments of the present invention. However, it is understood that the description and drawings constituting a part of this disclosure limit the present invention. Should not. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, the embodiment of the present invention can be modified as follows.

  In the embodiment described above, the narrow groove 20 is formed immediately above in the side wall view, but may be formed, for example, curved in an arcuate shape.

  When the narrow groove 20 is formed in an arcuate shape that is convex in the tire circumferential direction R, the block portion 30 is more easily deformed. Therefore, the pneumatic tire 1 can more effectively suppress uneven wear of the shoulder rib.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

DESCRIPTION OF SYMBOLS 1 ... Pneumatic tire, 2 ... Carcass, 4 ... Belt layer, 4a ... 1st belt layer,
4b ... 2nd belt layer, 6 ... Tread, 8 ... Main groove, 10, 12 ... Buttress part,
14 ... sidewall, 20 ... narrow groove, 20a ... upper end, 20b ... lower end,
22 ... narrow groove, 30 ... block part

Claims (2)

A belt layer provided on the outer side in the tire radial direction of the carcass and reinforcing the carcass;
A buttress portion formed between the tread and the sidewall and connected to the side end of the tread;
A tire in which a plurality of narrow grooves extending along the tread width direction are formed in the buttress portion,
The narrow groove is
In the side wall view of the tire, while tilting with respect to the tire normal along the tire radial direction,
In the cross section of the tire along the tread width direction and the tire radial direction, it is formed between a straight line extending from the tire radial direction inner end of the belt layer and orthogonal to the tire equator line, and the surface of the tread.
The narrow groove is formed in a first buttress portion continuous with one side end of the tread and a second buttress portion continuous with the other side end of the tread,
The tire is different from an inclination angle formed by the narrow groove formed in the first buttress portion with the tire normal and an inclination angle formed by the thin groove formed in the second buttress portion with the tire normal. 2. The tire according to claim 1 , wherein an angle of inclination between the narrow groove and the tire normal line is 2 degrees to 10 degrees in the side wall view.

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