JP2011178275A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire which suppresses the generation of shoulder wear, while suppressing the generation of rib tear. <P>SOLUTION: The pneumatic tire provided with a plurality of circumferential grooves extended in the tire circumferential direction includes: shoulder-side circumferential grooves 12 each having a linear opening in the tire circumferential direction and irregular groove walls in the tire circumferential direction; and a linear thin grooves 20 each formed in the tire circumferential direction between the shoulder-side circumferential groove 12 and a shoulder rib 32 on the outer side of the shoulder-side circumferential groove 12 in the tire width direction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a pneumatic tire provided with a circumferential groove.

  In pneumatic tires with straight circumferential grooves, long foreign objects such as metal rails and side groove lids enter the circumferential grooves, causing ribs near the groove openings in the circumferential grooves to be lost. It may be lost. This is called Libertia.

  Conventionally, a pneumatic tire has been proposed in which an opening is formed in a straight shape and a circumferential groove in which groove walls facing each other are formed in a zigzag shape (Patent Document 1). Since this pneumatic tire includes circumferential grooves in which groove walls facing each other are formed in a zigzag shape, foreign matter is unlikely to enter the circumferential grooves. Therefore, the occurrence of rib tears can be suppressed.

JP 2007-131217 A

  Since the circumferential groove of the conventional pneumatic tire described above has a groove wall formed in a zigzag shape, the rigidity of the shoulder rib varies along the tire circumferential direction. As a result, shoulder wear in which the shoulder rib wears faster than the center side rib tends to occur.

  An object of this invention is to provide the pneumatic tire which can suppress generation | occurrence | production of shoulder wear, suppressing generation | occurrence | production of a rib tear.

  The pneumatic tire of the present invention is a pneumatic tire provided with a plurality of circumferential grooves extending in the tire circumferential direction, the opening being linear along the tire circumferential direction, and the grooves along the tire circumferential direction. A wall is formed along the tire circumferential direction between the shoulder-side circumferential groove having an uneven wall, the shoulder-side circumferential groove, and the outer rib in the tire width direction than the shoulder-side circumferential groove. And a linear narrow groove.

  In addition, it is preferable that a straight narrow groove formed along the tire circumferential direction is further provided between the shoulder side circumferential groove and the inner rib in the tire width direction than the shoulder side circumferential groove. .

  Further, the shoulder side circumferential groove is from a groove bottom of the shoulder side circumferential groove at a projection intersection point where the groove walls facing each other when the shoulder side circumferential groove is viewed in the tire circumferential direction. Is preferably 0.45 times or more and 0.70 times or less the depth of the shoulder side circumferential groove.

  Moreover, it is preferable that the width | variety of the said narrow groove is 0.5 mm or more and 2.0 mm or less.

  Moreover, it is preferable that the depth of the said narrow groove is 0.5 to 1.0 times the depth of the said shoulder side circumferential groove.

  Moreover, it is preferable that the shape which projected the groove wall of the said shoulder side circumferential groove | channel from the tire radial direction outer side is a triangle, a trapezoid, or a semicircle.

  In addition, when the shoulder side circumferential groove is projected from the tire circumferential direction, the shape of the tread portion between the narrow groove and the groove bottom is preferably a triangle, a trapezoid, or a sector.

  According to the pneumatic tire of the present invention, it is possible to suppress the occurrence of shoulder wear while suppressing the occurrence of rib tears.

It is a figure which shows an example of the tread pattern of the pneumatic tire of embodiment. It is an enlarged view of the part shown with the dotted line of FIG. (A) is AA sectional drawing of FIG. 2, (b) is BB sectional drawing of FIG. 2, (c) is CC sectional drawing of FIG. FIG. 6 is a projection view in which a shoulder-side circumferential groove of a pneumatic tire according to Modification 1 is projected in the tire circumferential direction. (A)-(c) is an enlarged view of the shoulder side circumferential direction groove | channel of the pneumatic tire of the modification 2. FIG. (A), (b) is the projection which projected the shoulder side circumferential groove | channel of the pneumatic tire of the modification 3 to the tire circumferential direction. It is a figure which shows the tread pattern of the pneumatic tire of a prior art example.

<Embodiment>
Hereinafter, the pneumatic tire of this embodiment will be described in detail.
The pneumatic tire of the embodiment described below can be applied to heavy duty tires for trucks and buses defined in Chapter C of JATMA YEAR BOOK 2008 (Japan Automobile Tire Association Standard).

  In the following description, the tire width direction is a direction parallel to the rotation axis of the pneumatic tire. Further, the outward in the tire width direction is a direction away from the tire equator line CL in the tire width direction. The inner side in the tire width direction is a direction approaching the tire equator line CL in the tire width direction. Further, the tire circumferential direction is a direction in which the rotation axis of the pneumatic tire rotates around the rotation center. The tire radial direction is a direction orthogonal to the rotation axis of the pneumatic tire.

  First, the tread pattern of the pneumatic tire of this embodiment will be described with reference to FIG. Drawing 1 is a figure showing an example of the tread pattern of the pneumatic tire of this embodiment. As shown in FIG. 1, the pneumatic tire of this embodiment includes a plurality of circumferential grooves 10 extending in the tire circumferential direction. Moreover, the pneumatic tire of this embodiment includes a plurality of ribs 30 that are land portions extending continuously along the tire circumferential direction. The rib 30 is defined by the circumferential groove 10. The width of the circumferential groove 10 is 5 mm or more.

Of the plurality of circumferential grooves 10, the outermost circumferential groove in the tire width direction is defined as a shoulder-side circumferential groove 12. The detailed shape of the shoulder side circumferential groove 12 will be described later. Further, among the plurality of ribs 30, a rib on the outer side in the tire width direction than the shoulder side circumferential groove 12 is defined as a shoulder rib 32.
Further, as shown in FIG. 1, the pneumatic tire of the present embodiment includes a linear narrow groove 20 along the tire circumferential direction between the shoulder side circumferential groove 12 and the shoulder rib 32. In addition, the pneumatic tire of the present embodiment is a linear thin line along the tire circumferential direction between the shoulder side circumferential groove 12 and the rib 30 on the inner side in the tire width direction than the shoulder side circumferential groove 12. A groove 20 is provided.

Next, the detailed shape of the shoulder side circumferential groove 12 will be described with reference to FIGS. FIG. 2 is an enlarged view of a portion indicated by a dotted line in FIG. 3A is a cross-sectional view taken along the line AA in FIG. 2, FIG. 3B is a cross-sectional view taken along the line BB in FIG. 2, and FIG. 3C is a cross-sectional view taken along the line C-- in FIG. It is C sectional drawing. The shoulder side circumferential groove 12 is formed such that the opposed groove wall 16 is inclined toward the groove bottom 14.
As shown in FIGS. 2 and 3, the opening of the shoulder side circumferential groove 12 is linear along the tire circumferential direction. The width of the opening of the shoulder side circumferential groove 12 is, for example, 15 mm. In addition, as shown in FIG. 2, the groove bottom 14 of the shoulder side circumferential groove 12 has a shape meandering along the tire circumferential direction. Moreover, as FIG.2 and FIG.3 shows, the groove wall 16 of the shoulder side circumferential groove | channel 12 is uneven | corrugated shape along a tire circumferential direction. Further, as shown in FIG. 3, the groove wall 16 of the shoulder side circumferential groove 12 is inclined in the direction of the opposed groove wall 16. Therefore, the groove width of the shoulder side circumferential groove 12 becomes narrower from the opening toward the groove bottom 14. Moreover, as FIG. 3 shows, the angle which the groove wall 16 inclines differs along a tire circumferential direction. Therefore, the groove wall 16 of the shoulder side circumferential groove 12 has an uneven shape along the tire circumferential direction. The width of the groove bottom 14 is 2 mm, for example.

On the outer side in the tire width direction and the inner side in the tire width direction of the shoulder side circumferential groove 12, linear narrow grooves 20 extending in the tire circumferential direction are formed.
The width W of the narrow groove 20 is preferably 0.5 mm or more and 2.0 mm or less. By setting the width W of the narrow groove 20 to 0.5 mm or more and 2.0 mm or less, occurrence of shoulder wear can be further suppressed.
Further, the depth d of the narrow groove 20 is preferably not less than 0.5 times and not more than 1.0 times the depth D of the shoulder side circumferential groove 12. By setting the depth d of the narrow groove 20 to be not less than 0.5 times and not more than 1.0 times the depth D of the shoulder side circumferential groove 12, occurrence of shoulder wear can be further suppressed.

  As described above, the shoulder-side circumferential groove 12 of the pneumatic tire of the present embodiment has an opening that is linear along the tire circumferential direction, and a groove wall that is uneven along the tire circumferential direction. is there. In addition, the pneumatic tire according to the present embodiment includes the linear narrow groove 20 along the tire circumferential direction between the shoulder side circumferential groove 12 and the shoulder rib 32. Therefore, the inner end of the shoulder rib 32 in the tire width direction has a linear shape along the tire circumferential direction, and a difference in rigidity of the shoulder rib 32 hardly occurs along the tire circumferential direction. Further, the contact pressure of the contact end portion on the inner side in the tire width direction of the shoulder rib 32 concentrates on the protruding portion forming the groove wall of the shoulder side circumferential groove 12, and this protruding portion is easily worn. As a result, according to the pneumatic tire of the present embodiment, it is possible to suppress the occurrence of shoulder wear while suppressing the occurrence of rib tears.

  Further, the pneumatic tire according to the present embodiment has a linear narrow groove extending along the tire circumferential direction between the shoulder side circumferential groove 12 and the inner rib 30 in the tire width direction than the shoulder side circumferential groove 12. 20, the groove wall 16 of the rib 30 on the inner side in the tire width direction than the shoulder-side circumferential groove 12 is linear, and the rigidity difference of the rib 30 hardly occurs along the tire circumferential direction. Further, the ground pressure at the ground end of the rib 30 on the shoulder side circumferential groove 12 side concentrates on the projecting portion forming the groove wall of the shoulder side circumferential groove 12, and this projecting portion is likely to be worn. Therefore, it is possible to suppress the occurrence of rail wear at the end of the rib 30 on the shoulder side circumferential groove 12 side.

In general, when a vehicle equipped with a pneumatic tire rides on a step along a road shoulder, a stepped portion or the like is formed in the shoulder-side circumferential groove 12 that is the outermost in the tire width direction among the plurality of circumferential grooves 10. Easy to get foreign objects. In the pneumatic tire of the present embodiment, the shape of the shoulder-side circumferential groove 12 is the shape described with reference to FIGS. 2 and 3, thereby suppressing foreign matter from entering the shoulder-side circumferential groove 12. be able to.
In the present embodiment, among the plurality of circumferential grooves 10, only the shoulder side circumferential groove 12 has the shape described with reference to FIGS. 2 and 3. The shape of the circumferential groove 10 may be the shape described with reference to FIGS.

(Modification 1)
Next, a pneumatic tire according to Modification 1 will be described. The pneumatic tire of this modification is different from the embodiment described above in the inclination angle of the groove wall 16 of the shoulder side circumferential groove 12. Other configurations are the same as those of the above-described embodiment. Hereinafter, description of the part similar to the embodiment described above will be omitted, and the shape of the shoulder side circumferential groove 12 different from the embodiment described above will be described in detail with reference to FIG.

  FIG. 4 is a projection view in which the shoulder-side circumferential groove 12 of the pneumatic tire of the present modification is projected in the tire circumferential direction. In the projection view shown in FIG. 4, a portion where the groove walls 16 facing each other intersect is defined as a projection intersection 18. In the pneumatic tire of this modification, the height h from the groove bottom 14 to the projection intersection 18 is 0.45 times or more and 0.70 times or less the depth D of the shoulder side circumferential groove 12.

  The height h from the groove bottom 14 to the projection intersection 18 is set to 0.45 times or more the depth D of the shoulder side circumferential groove 12 to suppress the projection intersection 18 from being too close to the groove bottom 14. Can do. Therefore, when a foreign material enters the shoulder side circumferential groove 12, the foreign material can be prevented from entering the shoulder side circumferential groove 12 too deeply. As a result, the occurrence of rib tears can be suppressed.

  Further, by setting the height h from the groove bottom 14 to the projection intersection 18 to 0.70 times or less of the depth D of the shoulder side circumferential groove 12, the projection intersection 18 is prevented from being too close to the tread surface. be able to. Therefore, it can suppress that the inclination-angle of the groove wall 16 becomes large too much. Thereby, generation | occurrence | production of shoulder wear and generation | occurrence | production of a rib tear can be suppressed.

  As described above, the shoulder-side circumferential groove 12 of the pneumatic tire of this modification has a height h from the groove bottom 14 to the projection intersection 18 of 0.45 which is the depth D of the shoulder-side circumferential groove 12. It is not less than twice and not more than 0.70 times. Therefore, according to the pneumatic tire of this modification, it is possible to suppress the occurrence of shoulder wear while suppressing the occurrence of rib tears.

(Modification 2)
In the embodiment described above, the groove bottom 14 of the shoulder side circumferential groove 12 has a shape meandering along the tire circumferential direction. The shoulder side circumferential groove 12 of this modification is different from the embodiment described above in the shape of the groove bottom 14. Since the other structure of a pneumatic tire is the same as that of embodiment mentioned above, description is abbreviate | omitted. Hereinafter, with reference to FIG. 5, the shape of the shoulder side circumferential groove 12 of the pneumatic tire of this modification will be described.

  FIGS. 5A to 5C are diagrams in which the shoulder-side circumferential groove 12 of the pneumatic tire of the present modification is projected from the outer side in the tire radial direction. In the example shown in FIG. 5A, the shape obtained by projecting the groove wall 16 of the shoulder side circumferential groove 12 from the outer side in the tire radial direction is a triangle. In the example shown in FIG. 5B, the shape of the groove wall 16 of the shoulder side circumferential groove 12 projected from the outer side in the tire radial direction is a trapezoid. In the example shown in FIG. 5C, the shape of the groove wall 16 of the shoulder side circumferential groove 12 projected from the outer side in the tire radial direction is a semicircular shape.

  Similar to the embodiment described above, according to the pneumatic tire of the present modification, it is possible to suppress the occurrence of shoulder wear while suppressing the occurrence of rib tears.

(Modification 3)
In the embodiment described above, when the shoulder side circumferential groove 12 is projected from the tire circumferential direction, the shape of the tread portion between the narrow groove 20 and the groove bottom 14 is a triangle. In the pneumatic tire of this modification, when the shoulder-side circumferential groove 12 is projected from the tire circumferential direction, the shape of the tread portion between the narrow groove 20 and the groove bottom 14 is different from the above-described embodiment. Since the other structure of a pneumatic tire is the same as that of embodiment mentioned above, description is abbreviate | omitted. Hereinafter, the shape of the shoulder-side circumferential groove 12 of the pneumatic tire of this modification will be described with reference to FIG.

  6A and 6B are views in which the shoulder-side circumferential groove 12 of the pneumatic tire of the present modification is projected from the tire circumferential direction. In the example shown in FIG. 6A, when the shoulder side circumferential groove 12 is projected from the tire circumferential direction, the shape of the tread portion between the narrow groove 20 and the groove bottom 14 is a trapezoid. In the example shown in FIG. 6B, when the shoulder-side circumferential groove 12 is projected from the tire circumferential direction, the shape of the tread portion between the narrow groove 20 and the groove bottom 14 is a sector shape.

Similar to the embodiment described above, according to the pneumatic tire of the present modification, it is possible to suppress the occurrence of shoulder wear while suppressing the occurrence of rib tears.
In addition, embodiment and the modification which were demonstrated above can be combined suitably.

  The test which confirms the effect of this invention was done using the various pneumatic tires. The tire size was 11R22.5, and the air pressure conditions defined in JATMA YEAR BOOK 2008 (Japan Automobile Tire Association Standard) were used. The load conditions were the conditions specified in JATMA YEAR BOOK 2008 (Japan Automobile Tire Association Standard). Each test tire was mounted on the front shaft of a 2-D vehicle, and the following tests were performed.

(Shoulder wear resistance)
A test vehicle equipped with each test tire was run on a test course for 100,000 km, and the wear amount of the ribs and shoulder ribs in the center portion was measured. The difference in the amount of wear between the ribs at the center and the shoulder ribs was evaluated with an index value where the conventional example was 100. The larger this value, the less shoulder wear occurs and the better the shoulder wear resistance.

(Rib tear resistance)
The test vehicle equipped with each test tire was run 20 times while turning a curb with a height of 200 mm. Then, the rib tear which generate | occur | produced in the shoulder rib of each test tire was measured.

(Conventional example, Examples 1 to 5)
The effect of changing the ratio h / D of the height h from the groove bottom 14 to the projection intersection 18 with respect to the depth D of the shoulder-side circumferential groove 12 using the pneumatic tires of the conventional examples and Examples 1 to 5. I investigated.
First, a conventional pneumatic tire will be described with reference to FIG. FIG. 7 is a diagram showing a tread pattern of a conventional pneumatic tire.
The conventional pneumatic tire is different from Modification 1 in that a narrow groove is not formed between the shoulder side circumferential groove 12 and the shoulder rib 32. Moreover, the pneumatic tire of the conventional example is a modification 1 in that no narrow groove is formed between the shoulder side circumferential groove 12 and the rib 30 on the inner side in the tire width direction than the shoulder side circumferential groove 12. And different. Other configurations are the same as in the first modification. The conventional pneumatic tire has an h / D of 0.60.

  Next, the pneumatic tire of each example will be described with reference to FIG. The pneumatic tire of each Example described below is the same as the pneumatic tire described in Modification 1 described above. The pneumatic tire of each example has a ratio h / D of the height h from the groove bottom 14 to the projection intersection 18 with respect to the depth D of the shoulder side circumferential groove 12, the width W of the narrow groove 20, the shoulder side circumferential groove. The ratio d / D of the depth d of the narrow groove 20 to the depth D of 12 is different from each other.

W of the pneumatic tires of Examples 1 to 5 is 1.0 mm. Moreover, all of d / D of the pneumatic tire of Examples 1-5 is 1.0.
H / D of the pneumatic tire of Example 1 is 0.40.
H / D of the pneumatic tire of Example 2 is 0.45.
H / D of the pneumatic tire of Example 3 is 0.60.
H / D of the pneumatic tire of Example 4 is 0.70.
H / D of the pneumatic tire of Example 5 is 0.75.

Table 1 shows the test results of the shoulder wear resistance in the conventional examples and Examples 1 to 5.

From the results of Table 1, it can be seen that in Examples 1 to 5, the shoulder wear resistance is improved as compared with the conventional pneumatic tire. This indicates that the pneumatic tires of Examples 1 to 5 can suppress the occurrence of shoulder wear by including the narrow grooves 20.
Moreover, from the result of Table 1, in Examples 2-4 which satisfy | fills 0.45 <= h / D <= 0.70, it turns out that shoulder abrasion resistance improves more.
In any of the examples, the rib tear resistance was not inferior to that of the conventional example.

(Conventional example, Examples 3, 6-9)
Using the conventional example and the pneumatic tires of Examples 3 and 6 to 9, the effect of changing the width W of the narrow groove 20 was examined.
H / D of the pneumatic tires of Examples 3 and 6 to 9 is 0.60. Moreover, d / D of the pneumatic tires of Examples 3 and 6 to 9 is 1.0.
W of the pneumatic tire of Example 6 is 0.4 mm.
W of the pneumatic tire of Example 7 is 0.5 mm.
W of the pneumatic tire of Example 3 is 1.0 mm.
W of the pneumatic tire of Example 8 is 2.0 mm.
W of the pneumatic tire of Example 9 is 2.5 mm.

Table 2 shows the test results of shoulder wear resistance in the conventional examples and Examples 3 and 6 to 9.

From the results of Table 2, it can be seen that in Examples 3 and 6 to 9, the shoulder wear resistance is improved as compared with the conventional pneumatic tire. This indicates that the pneumatic tires of Examples 3 and 6 to 9 can suppress the occurrence of shoulder wear by providing the narrow grooves 20.
Moreover, from the results of Table 2, it can be seen that in Examples 3, 7, and 8 satisfying 0.5 ≦ W ≦ 2.0, the shoulder wear resistance is further improved.
In any of the examples, the rib tear resistance was not inferior to that of the conventional example.

(Conventional example, Examples 3, 10, and 11)
The effect of changing the ratio d / D of the depth d of the narrow groove 20 to the depth D of the shoulder-side circumferential groove 12 was examined using the conventional tires and pneumatic tires of Examples 3, 10, and 11.
H / D of the pneumatic tires of Examples 3, 10, and 11 is 0.60. Moreover, W of the pneumatic tires of Examples 3, 10, and 11 is 1.0 mm.
The d / D of the pneumatic tire of Example 10 is 0.4.
The d / D of the pneumatic tire of Example 11 is 0.5.
The d / D of the pneumatic tire of Example 3 is 1.0.

Table 3 shows the test results of shoulder wear resistance in the conventional examples and Examples 3, 10 and 11.

From the results of Table 3, it can be seen that in Examples 3, 10, and 11, the shoulder wear resistance is improved as compared with the conventional pneumatic tire. This indicates that the pneumatic tires of Examples 3, 10, and 11 are provided with the narrow grooves 20 so that the occurrence of shoulder wear can be suppressed.
Further, from the results of Table 3, it can be seen that in Examples 3 and 11 satisfying 0.5 ≦ d / D ≦ 1.0, the shoulder wear resistance is further improved.
In any of the examples, the rib tear resistance was not inferior to that of the conventional example.

  From the results shown in Tables 1 to 3, it was found that the pneumatic tire of the present invention can suppress the occurrence of shoulder wear while suppressing the occurrence of rib tear.

10 circumferential groove 12 shoulder side circumferential groove 14 groove bottom 16 groove wall 18 projected intersection 20 narrow groove 30 rib 32 shoulder rib

Claims (7)

A pneumatic tire comprising a plurality of circumferential grooves extending in the tire circumferential direction,
A shoulder side circumferential groove in which the opening is linear along the tire circumferential direction and the groove wall is uneven along the tire circumferential direction;
A linear narrow groove formed along the tire circumferential direction between the shoulder side circumferential groove and a rib on the outer side in the tire width direction than the shoulder side circumferential groove;
A pneumatic tire characterized by comprising:   The straight line-shaped narrow groove formed along the tire circumferential direction is further provided between the shoulder-side circumferential groove and a rib on the inner side in the tire width direction than the shoulder-side circumferential groove. The described pneumatic tire.   The shoulder-side circumferential groove is a height from a bottom of the shoulder-side circumferential groove at a projected intersection that is a portion where the opposed groove walls intersect when the shoulder-side circumferential groove is viewed in the tire circumferential direction. The pneumatic tire according to claim 1, wherein the tire has a depth not less than 0.45 times and not more than 0.70 times the depth of the shoulder side circumferential groove.   The pneumatic tire according to any one of claims 1 to 3, wherein the narrow groove has a width of not less than 0.5 mm and not more than 2.0 mm.   The pneumatic tire according to any one of claims 1 to 4, wherein a depth of the narrow groove is not less than 0.5 times and not more than 1.0 times a depth of the shoulder side circumferential groove.   The pneumatic tire according to any one of claims 1 to 5, wherein a shape obtained by projecting the groove wall of the shoulder side circumferential groove from the outer side in the tire radial direction is a triangle, a trapezoid, or a semicircular shape.   The shape of the tread portion between the narrow groove and the groove bottom when projecting the shoulder side circumferential groove from the tire circumferential direction is a triangle, a trapezoid, or a fan shape. Pneumatic tire described in 2.