JP5144116B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that is used in heavy-duty vehicles such as trucks and buses and that can exhibit tire performance in both a good road area and a bad road area.

  Heavy-duty pneumatic tires are used for heavy-duty vehicles such as trucks and buses, and have a rib pattern that is excellent in quietness and suitable for traveling on a good road (see, for example, Patent Document 1), on a rough road. A lug pattern (see, for example, Patent Document 2) that is suitable for traveling and excellent in driving force and braking force, or a rib lug pattern as shown in FIG. 5 that combines the characteristics of the lug pattern and the rib pattern is known. It has been.

  A tread 102 of the pneumatic tire 100 shown in FIG. 5 in which the tread pattern is a rib lug pattern is formed with a center circumferential main groove 104 extending in a zigzag shape in the tire circumferential direction at the center in the tire width direction. On both sides of the circumferential main groove 104, shoulder circumferential main grooves 106 are also formed that extend in a zigzag shape in the tire circumferential direction.

  In the tread 102, a center rib 108 is formed between the center circumferential main groove 104 and the shoulder circumferential main groove 106, and a shoulder rib 110 is formed on the outer side in the tire axial direction of the shoulder circumferential main groove 106.

The center rib 108 is formed with a plurality of upwardly rising shallow grooves 112 that connect the shoulder circumferential main groove 106 and the center circumferential main groove 104 at intervals.
In the shoulder rib 110, a plurality of lug grooves 114 are formed at intervals in the circumferential direction on the ground contact end 102E side.

The center rib 108 is inclined between the shallow groove 112 and the shallow groove 112 in the same direction as the shallow groove 112, and the groove depth is shallower than the shoulder circumferential main groove 106 and the center circumferential main groove 104. In addition, a bag hot water groove 116 whose both ends terminate in the rib is formed.
Further, a short sipe 118 is formed at the tip of the convex portion of the center rib 108 on the shoulder circumferential main groove 106 side.
JP 2003-127616 A JP 2001-55017 A

  However, with conventional lag pattern pneumatic tires, there is a problem that uneven wear worsens when traveling on good roads such as asphalt, etc. There is an inferior problem.

  On the other hand, with conventional rib lug pattern pneumatic tires, when there is a lot of running on good roads such as asphalt, there remains a problem that uneven wear (heel and toe wear) tends to occur near the lug grooves, In addition, there still remains a problem of causing river wear on both sides of the zigzag circumferential main groove.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a pneumatic tire that can improve running on bad roads and good roads and improve uneven wear and the like.

  The invention according to claim 1 is an air in which four ribs defined by three circumferential grooves extending zigzag along the tire circumferential direction are provided in the tread, and lug grooves are formed in the ribs on the shoulder side. W1: W2 = 1: 1 ± 0, where W1 is the new width of the two ribs on the tire center side and W2 is the new width of the two ribs on the shoulder side. 0.1, and in the worn tread where the groove depth of the circumferential groove remains 1 mm or more, the width of the rib on the center side ≦ the width of the rib on the shoulder side ≦ 1.25 × the width of the rib on the center side When the groove width of the circumferential groove on the tire center side is L1, and the groove width of the two circumferential grooves on the shoulder side is L2, 1 <L1 / L2 <1.3 and 13. Satisfying 0 mm <L1 <17.0 mm, 2 on the tire center side A plurality of shallow grooves that are transverse to the tire width direction and have a groove depth of 2.0 to 7.0 mm are formed in the ribs at intervals in the tire circumferential direction. Satisfies 10 ° ≦ θ ≦ 20 °, where θ is the angle with respect to the normal line standing on the tread surface, and the angle of the convex portion on the circumferential groove side of the rib is a concave portion. The angle of the lug groove is set to be smaller than the angle of the portion and is gradually changed between the convex portion and the concave portion, and the dimension of the lug groove in the tire axial direction is W3 in the region inside the ground contact end of the tread. When the dimension of the lug groove in the tire circumferential direction is W4, 0 <W3 ≦ 10 mm, 0 <W4 ≦ 25 mm is satisfied, and the groove bottom of the circumferential groove on the shoulder side and the groove bottom of the lug groove are Tire diametrically outward from the imaginary plane to be connected, and tie from the tread grounding edge The volume of the lug groove measured in the axially inner region S1, when the volume of the shoulder ribs and S2, are satisfied 0 <S1 ≦ 0.05S2, is characterized by.

Next, the operation of the pneumatic tire according to claim 1 will be described.
In the pneumatic tire 10 of the present embodiment, the convex portion that protrudes toward the groove side of each rib has a negative effect on uneven wear properties because the ground pressure increases locally when side force is input. The ground contact pressure is relatively lowered by relatively reducing the angle to reduce the rigidity.

  On the other hand, the recesses that are recessed toward the groove side of each rib are better to reduce the angle of the groove wall from the above viewpoint, but if the angle of the groove wall is reduced, the rigidity of the entire rib including the protrusions is reduced. It becomes relatively small and tears are likely to occur.

In addition, when the angle of a groove wall is enlarged by a recessed part, the tear property of a convex part is also ensured. In addition, with the concave shape, even if the angle of the groove wall is increased, the local contact pressure is unlikely to increase when the side force is input.
Therefore, the angle of the groove wall of the concave portion is made relatively large with respect to the groove wall of the convex portion.

  Further, the angle θ of the groove wall of the center circumferential main groove and the groove wall of the shoulder circumferential main groove satisfies 10 ° ≦ θ ≦ 20 °, and the angle of the portion which is a convex portion on the groove side of each rib Is set to be smaller than the angle of the concave portion, and gradually changes between the convex portion on the groove side and the concave portion. While suppressing the occurrence of tears, uneven wear due to running on good roads can be suppressed, and both bad road running and good road running can be achieved.

When the angle θ of the groove wall exceeds 20 °, the rigidity is increased and the tear can be suppressed. However, the contact pressure at the end of the rib is increased when the side force is input, and the uneven wear property is deteriorated.
On the other hand, when the angle θ of the groove wall is less than 10 °, the rigidity is lowered and tear is likely to occur.

  If the relationship between the new width W1 of the center rib and the new width W2 of the shoulder rib does not satisfy W1: W2 = 1: 1 ± 0.1, the contact pressure between the center rib and the shoulder rib is uniform. It becomes inappropriate because uneven wear deteriorates.

  Next, in a tread in a worn state in which the groove depth of the center circumferential main groove and the shoulder circumferential main groove remains 1 mm or more, the width of the center rib ≦ the width of the shoulder rib ≦ 1.25 × the width of the center rib If not satisfied, even if the tread is worn, the contact pressure between the center rib and the shoulder rib is not uniform, and the uneven wear property is deteriorated.

  When the relationship between the groove width L1 of the center circumferential main groove and the groove width L2 of the shoulder circumferential main groove does not satisfy 1 <L1 / L2 <1.3 and 13.0 mm <L1 <17.0 mm, River wear wear worsens.

When the depth of the shallow groove is less than 2.0 mm, traction is insufficient at the initial stage of wear.
On the other hand, when the groove depth of the shallow groove is larger than 7.0 mm, the uneven wear property of the center rib is deteriorated.

  When 0 <W3 ≦ 10mm, 0 <W4 ≦ 25mm, and 0 <S1 ≦ 0.05S2 are not satisfied in the area inside the tread's ground contact edge, the high wear area (the tread wears 1mm because it wears 1mm) When necessary, for example, on a good road such as an asphalt road surface), uneven wear on the shoulder side of the tread deteriorates.

  The invention according to claim 2 is the pneumatic tire according to claim 1, wherein the top position of the bottom of the circumferential groove on the tire center side is set lower than the tread surface of the tread when new. It is characterized in that a formed stone biting prevention protrusion is formed.

Next, the operation of the pneumatic tire according to claim 2 will be described.
In the pneumatic tire according to claim 2, when driving on a rough road, the stone biting prevention protrusion comes into contact with the pebbles and prevents entry into the circumferential groove, thereby preventing the occurrence of cracks due to stone biting. Moreover, even if a pebbles enter, it will be easy to discharge because the pebbles are elastically pressed.

  As described above, since the pneumatic tire according to claim 1 has the above-described configuration, it has an excellent effect of being able to improve both uneven running and the like while simultaneously traveling on rough roads and good roads. .

  Moreover, since the pneumatic tire according to claim 2 has the above-described configuration, it has an excellent effect that it is possible to prevent the occurrence of cracks due to stone biting.

Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, the tread 12 of the pneumatic tire 10 has a center circumferential main groove 14 formed in the center in the tire width direction, and shoulder circumferential main grooves on both sides of the center circumferential main groove 14. 16 is formed.
Both the center circumferential main groove 14 and the shoulder circumferential main groove 16 extend in a zigzag shape in the tire circumferential direction (arrow A direction and arrow B direction).

In the tread 12, a center rib 18 is formed between the center circumferential main groove 14 and the shoulder circumferential main groove 16, and a tire rib direction outer side of the shoulder circumferential main groove 16 is a shoulder rib 20.
In the center rib 18, a plurality of shallow grooves 22 are formed at a distance from each other so as to connect the shoulder circumferential main groove 16 and the center circumferential main groove 14.
A plurality of lug grooves 24 are formed in the shoulder rib 20 at intervals in the circumferential direction on the ground contact end 12E side.

  In this embodiment, when the width of the center rib 18 when new is W1 and the width of the shoulder rib 20 when new is W2, W1: W2 = 1: 1 ± 0.1 is satisfied. The width of the center rib 18 and the width of the shoulder rib 20 are both average values measured in the tread width direction on the tread 12 tread surface.

  In the present embodiment, in the tread 12 in a worn state in which the groove depths of the center circumferential main groove 14 and the shoulder circumferential main groove 16 remain 1 mm or more, the width of the center rib ≦ the width of the shoulder rib 20 ≦ 1.25. X The width of the center rib 18 is satisfied.

  In the present embodiment, when the tread width is TW, the groove width of the center circumferential main groove 14 is L1, and the groove width of the shoulder circumferential main groove 16 is L2, 1 <L1 / L2 <1.3, and 13.0 mm <L1 <17.0 mm is satisfied. The groove width L1 of the center circumferential main groove 14 and the groove width L2 of the shoulder circumferential main groove 16 are both average values.

When the groove depth of the center circumferential main groove 14 in a new tread is OTD (see FIG. 2), the groove depth of the shoulder circumferential main groove 16 is OTD (see FIG. 3), and the tread width is TW, It is preferable to satisfy OTD / TW ≦ 0.085.
In the present embodiment, the groove depth of the shallow groove 22 is set in a range of 2.0 to 7.0 mm.

As shown in FIGS. 2 and 3, in the present embodiment, the angle with respect to the normal line standing on the tread surface is defined as θ in the groove wall of the center circumferential main groove 14 and the groove wall of the shoulder circumferential main groove 16. Sometimes, 10 ° ≦ θ ≦ 20 ° is satisfied, and the groove wall angle at the groove portion of the center rib 18 and the shoulder rib 20 in the tread plan view is a recess portion. It is set to be smaller than the groove wall angle and gradually changes between the convex portion and the concave portion.
In addition, the angle difference between the groove wall angle (minimum value) at the convex portion and the groove wall angle (maximum value) at the concave portion is preferably 5 ° to 10 °, and more preferably 8 ° to 10 °.

  As shown in FIG. 1, in this embodiment, when the dimension of the lug groove 24 in the tire axial direction is W3 and the dimension of the lug groove 24 in the tire circumferential direction is W4 inside the ground contact end 12E, 0 <W3 ≦ 10 mm and 0 <W4 ≦ 25 mm are satisfied. In addition, the dimension W3 in the tire axial direction of the lug groove 24 and the dimension W4 in the tire circumferential direction of the lug groove 24 are both average values.

  As shown in FIG. 4, in the present embodiment, the grounding end 12E of the tread 12 is provided on the outer side in the tire radial direction from the virtual plane FP1 that connects the groove bottom of the shoulder circumferential main groove 16 and the groove bottom of the lug groove 24. When the volume of the lug groove 24 measured in the region inside the tire axial direction from the virtual plane FP2 along the passing tire radial direction is S1, and the volume of the shoulder rib 20 is S2, 0 <S1 ≦ 0.05S2 is satisfied. doing.

  Here, the tread width TW means that the pneumatic tire is mounted on a standard rim specified in JATMA YEAR BOOK (2003 edition, Japan Automobile Tire Association Standard) and the maximum load in the applicable size and ply rating in JATMA YEAR BOOK One of the tread parts in the tire width direction that contacts the road surface when 100% of the internal pressure corresponding to the capacity (internal pressure-load capacity in bold) is filled with 100% of the internal pressure (maximum air pressure) It is the dimension measured along the tire width from one end to the other end.

Outside Japan, the load is the maximum load (maximum load capacity) of a single wheel at the applicable size described in the following standard, and the internal pressure is the maximum load (maximum load) of a single wheel described in the following standard. The rim is a standard rim (or “Approved Rim” or “Recommended Rim”) in the applicable size described in the following standards.
The standards are determined by industry standards that are valid in the region where the tire is produced or used. For example, it is “The Tire and Rim Association Inc. Year Book” in the United States, and “The European Tire and Rim Technical Organization Standards Manual” in Europe.

Further, it is preferable that TW / OW ≦ 0.85 is satisfied when the total width of the tire is OW.
As shown in FIGS. 1 and 2, a plurality of stone biting prevention protrusions 26 are formed on the groove bottom of the center circumferential main groove 14 along the groove longitudinal direction.
The stone biting prevention protrusion 26 is set such that the top position is lower than the tread surface of the tread 12 when new.

(Function)
In the pneumatic tire 10 of the present embodiment, the convex portion that protrudes toward the groove side of each rib has a negative effect on uneven wear properties because the ground pressure increases locally when side force is input. The ground contact pressure is relatively lowered by relatively reducing the angle to reduce the rigidity.

  On the other hand, the recesses that are recessed toward the groove side of each rib are better to reduce the angle of the groove wall from the above viewpoint, but if the angle of the groove wall is reduced, the rigidity of the entire rib including the protrusions is reduced. It becomes relatively small and tears are likely to occur.

In addition, when the angle of a groove wall is enlarged by a recessed part, the tear property of a convex part is also ensured. In addition, with the concave shape, even if the angle of the groove wall is increased, the local contact pressure is unlikely to increase when the side force is input.
Therefore, the angle of the groove wall of the concave portion is made relatively large with respect to the groove wall of the convex portion.

  Further, the angle θ of the groove wall of the center circumferential main groove 14 and the groove wall of the shoulder circumferential main groove 16 satisfies 10 ° ≦ θ ≦ 20 °, and is a convex portion on the groove side of each rib The angle is set to be smaller than the angle of the concave portion and gradually changes between the convex portion on the groove side and the concave portion. While suppressing the occurrence of tears due to running, uneven wear due to running on good roads can be suppressed, and both bad road running and good road running can be achieved.

Here, when the angle θ of the groove wall exceeds 20 °, the rigidity becomes high and the tear can be suppressed, but the contact pressure at the rib end portion becomes high at the time of side force input, and the uneven wear property deteriorates.
On the other hand, when the angle θ of the groove wall is less than 10 °, the rigidity is lowered and tear is likely to occur.

  Further, in the pneumatic tire 10 of the present embodiment, the stone biting prevention protrusion 26 is provided on the groove bottom of the center circumferential main groove 14, so that the stone biting prevention protrusion 26 abuts on the pebbles when traveling on a rough road, and the center circumferential direction It is possible to prevent entry into the main groove 14 and to prevent generation of cracks due to stone biting. Moreover, even if a pebbles enter, it will be easy to discharge because the pebbles are elastically pressed. The stone biting prevention protrusion 26 may be provided in the shoulder circumferential main groove 16.

  If the relationship between the new width W1 of the center rib 18 and the new width W2 of the shoulder rib 20 does not satisfy W1: W2 = 1: 1 ± 0.1, the center rib 18 and the shoulder rib 20 The ground contact pressure is not uniform, and uneven wear is deteriorated, which is inappropriate.

  Next, in the tread 12 in a worn state where the groove depths of the center circumferential main groove 14 and the shoulder circumferential main groove 16 remain 1 mm or more, the width of the center rib ≦ the width of the shoulder rib 20 ≦ 1.25 × center. If the width of the rib 18 is not satisfied, the contact pressure between the center rib 18 and the shoulder rib 20 is not uniform even after the tread 12 is worn, and the uneven wear property is deteriorated.

  The relationship between the groove width L1 of the center circumferential main groove 14 and the groove width L2 of the shoulder circumferential main groove 16 does not satisfy 1 <L1 / L2 <1.3 and 13.0 mm <L1 <17.0 mm. If the river wear is worse.

When the depth of the shallow groove 22 is less than 2.0 mm, traction is insufficient at the initial stage of wear.
On the other hand, when the groove depth of the shallow groove 22 is larger than 7.0 mm, the uneven wear property of the center rib 18 is deteriorated.

  When 0 <W3 ≦ 10 mm, 0 <W4 ≦ 25 mm, and 0 <S1 ≦ 0.05S2 are not satisfied in the region inside the ground contact end 12E of the tread 12, a high wear region (15000 km or more because the tread wears 1 mm) When traveling is required (for example, traveling on a good road such as an asphalt road surface), uneven wear on the shoulder side of the tread 12 is deteriorated.

  When OTD / TW ≦ 0.085 is not satisfied, the rigidity of the center rib 18 and the shoulder rib 20 becomes too small, and a tear is likely to occur particularly when traveling on a rough road.

  Note that in the pneumatic tire 10 of the present embodiment, no sipes are provided at portions that are convex on the groove side of the center rib 18 and the shoulder rib 20. If a sipe is provided on the convex portion, a tear is generated when traveling on a rough road, and the tire appearance is remarkably deteriorated.

  Further, in the pneumatic tire 10 of the present embodiment, the bag depth groove is shallow between the shallow groove 22 and the shallow groove 22 of the center rib 18, and no bag hot water groove having both ends terminating in the rib is provided. When the bag hot water groove is provided, when there is much traveling on a good road, uneven wear (heel and toe wear) occurs before and after the bag hot water groove.

(Test example)
In order to confirm the effect of the present invention, one type of tire of an example to which the present invention was applied, six types of comparative tires, and one type of conventional tire were prepared, and an actual vehicle running test was performed.
The actual vehicle equipped with the test tire was run on the good road and the bad road to the end of wear (the remaining groove depth of the circumferential groove 3 mm), and the partial wear and tear properties were examined.
For evaluation of uneven wear, the volume of uneven wear was measured, and an index display with the reciprocal of the wear volume of the conventional example as 100 was used. It shows that it is excellent in uneven wear property, so that a numerical value is large.
For evaluation of tear properties, the depth, length, and number of tears were comprehensively determined, and the index was displayed as the conventional example 100. It shows that it is excellent in tear property, so that a numerical value is large.
The evaluation is as shown in Tables 1 and 2 below.

In addition, the tire of an Example is a tire of embodiment mentioned above, and the tire of a prior art example is a tire which has the pattern shown in FIG. 5 demonstrated by the prior art. The tire of the comparative example has almost the same pattern as the example, but the dimensions and angles of the respective parts are different.
The size of each tire is 12.00R20.

試験の結果、本発明の適用された実施例のタイヤは、従来例のタイヤに比較して、偏摩耗性、及びテアー性に対して優れていることが分かる。

As a result of the test, it can be seen that the tire of the example to which the present invention is applied is superior in uneven wear and tear properties as compared with the tire of the conventional example.

It is a top view of the tread of the pneumatic tire concerning one embodiment of the present invention. FIG. 2 is a cross-sectional view of the tread shown in FIG. 1 taken along line 2-2. FIG. 3 is a sectional view of the tread shown in FIG. 1 taken along line 3-3. FIG. 4 is a cross-sectional view of the tread shown in FIG. 1 taken along line 4-4. It is a top view of the tread of the conventional rib lug pattern.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Pneumatic tire 12 Tread 14 Center circumferential direction main groove 16 Shoulder circumferential direction main groove 18 Center rib 20 Shoulder rib 22 Shallow groove 24 Lug groove 26 Stone biting prevention protrusion

Claims (2)

A pneumatic tire comprising treads with four ribs defined by three circumferential grooves extending in a zigzag shape along the tire circumferential direction, and formed with lug grooves on the ribs on the shoulder side,
When the new width of the two ribs on the tire center side is W1 and the new width of the two ribs on the shoulder side is W2, W1: W2 = 1: 1 ± 0.1 is satisfied,
In the tread in a worn state in which the groove depth of the circumferential groove remains 1 mm or more, the center side rib width ≦ the shoulder side rib width ≦ 1.25 × the center side rib width is satisfied,
When the groove width of the circumferential groove on the tire center side is L1, and the groove width of the two circumferential grooves on the shoulder side is L2, 1 <L1 / L2 <1.3 and 13.0 mm <L1 < Satisfy 17.0mm
In the two ribs on the tire center side, a plurality of shallow grooves that are traversed in the tire width direction and have a groove depth of 2.0 to 7.0 mm are formed at intervals in the tire circumferential direction.
The groove wall of the circumferential groove satisfies 10 ° ≦ θ ≦ 20 ° when θ is an angle with respect to the normal line standing on the tread surface, and is a convex portion on the circumferential groove side of the rib. The angle of the part is set smaller than the angle of the part that is a concave part, and gradually changes between the convex part and the concave part,
0 <W3 ≦ 10 mm, 0 <W4 ≦ 25 mm, where W3 is the dimension in the tire axial direction of the lug groove and W4 is the dimension in the tire circumferential direction of the lug groove in the region inside the ground contact edge of the tread. Satisfied,
The lug groove measured in a region radially outside the imaginary plane connecting the groove bottom of the circumferential groove on the shoulder side and the groove bottom of the lug groove, and on the inner side in the tire axial direction from the ground contact end of the tread When S1 is the volume of the shoulder and the volume of the rib on the shoulder side is S2, 0 <S1 ≦ 0.05S2 is satisfied.
A pneumatic tire characterized by that.     The stone biting prevention protrusion by which the position of the top part was set lower than the tread surface of the tread at the time of a new article is formed in the groove bottom of the circumferential groove on the tire center side. Pneumatic tires.

Images