JP5085984B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire having a block pattern on a tread, and in particular, a pneumatic tire capable of suppressing heel and toe wear in a block in order to maintain a uniform wear state of the tread until the end of wear. About.

In a pneumatic tire having a block pattern, heel and toe wear occurs on the block.
In order to suppress the heel and toe wear, for example, in Patent Document 1, in order to suppress the progress of the heel and toe wear of the shoulder block, the circumferential direction is positioned away from the ground contact end in the axial direction. It is described that a narrow groove extending in the direction is arranged.
JP 7-228109 A

However, the conventional method can suppress the heel and toe wear of the shoulder, which is the outermost block in the tread width direction, but the block between the circumferential main grooves, that is, the tire width direction than the shoulder block. Heel and toe wear that occurs on the inner block could not be suppressed.
In addition, not only the circumferential force but also lateral force is input to the block during running. In particular, when a lateral force is applied, wear starts from the outermost corner in the tread width direction on the kicking side of the block, and uneven wear gradually progresses inward toward the stepping side of the block.
The conventional technology for suppressing heel-and-toe wear was designed to suppress wear from the kicked-out edge that progresses toward the stepping side along the circumferential direction, so the tread width on the kicked-out side of the block Effective heel-and-toe wear that begins to wear from the outermost corner in the direction and gradually progresses toward the stepping side of the block. Could not be suppressed.

  The present invention has been made to solve the above-mentioned problem, and begins to wear from the outermost corner in the tread width direction on the kicking side of the block and gradually develops uneven wear diagonally inward toward the stepping side of the block. An object of the present invention is to provide a pneumatic tire capable of effectively suppressing heel-and-toe wear.

  As a result of detailed investigations and various studies by the inventor on the generation process of the heel and toe wear, the heel and toe wear generated on the block is particularly difficult when the lateral force is applied. It begins to wear from the corner of the outermost edge in the tread width direction, and then gradually wears inwardly toward the stepping side of the block, but in the vicinity of the corner, against the bisector of the corner It has been found that the development of the uneven wear can be effectively suppressed by forming narrow grooves extending in the intersecting direction and setting the positions of the narrow grooves and the like optimally.

  The invention according to claim 1 is a pneumatic tire in which a tread includes a plurality of blocks defined by a plurality of circumferential grooves extending in the circumferential direction and a plurality of lug grooves extending in a direction intersecting the circumferential groove. 90 ° ± 20 with respect to the bisector of the two sides constituting the first corner on the kicking side of the block and on the first corner on the outermost side in the tread width direction The first narrow groove intersecting at an angle of 0 ° and having a groove width narrower than that of the lug groove and a shallow groove depth is formed, and measurement is performed on the bisector. The distance from the first corner to the first narrow groove is set to 5 mm or more and 10 mm or less.

Next, the operation of the pneumatic tire according to claim 1 will be described.
For example, when the vehicle corners, a large lateral force is exerted on the block located radially outward of the turn from the tire equator plane (from the vehicle outer side to the tire equator plane) in the tread of the pneumatic tire on the radially outer side of the turn. Works. When force in the tire circumferential direction and lateral force act on the block, the block is biased toward the side of the kick-out and from the outermost first corner in the tread width direction toward the stepping-in side (center side of the block). Wear is about to progress.

It intersects at the angle of 90 ° ± 20 ° with the bisector of the two sides that constitute the first corner on the block kicking side and the first corner on the outermost side in the tread width direction. In addition, by forming the first narrow groove having a groove width narrower than that of the circumferential groove and the lug groove and having a shallow groove depth , uneven wear occurring on the first corner side is reduced. It can suppress progressing diagonally inside (block center side) toward the stepping side.

  When the direction of the first narrow groove deviates from 90 ° ± 20 ° with respect to the bisector, three corner portions of the triangular portion between the first corner portion and the first narrow groove The angle of any one of the corner portions becomes too small, and lack of rigidity causes block missing.

In addition, when the distance from the first corner portion measured on the bisector to the first narrow groove is less than 5 mm, the block rigidity is low (between the first corner portion and the first narrow groove). (Triangle part) becomes easy to chip.
On the other hand, when the distance from the first corner to the first narrow groove measured on the bisector exceeds 10 mm, the distance from the first corner to the first narrow groove becomes too long, It becomes impossible to suppress the progress of the to-to-wear.

  According to a second aspect of the present invention, in the pneumatic tire according to the first aspect, the second corner portion is configured on the stepping side of the block and on the second corner portion side on the outermost side in the tread width direction. A second line that intersects the bisector of two sides at an angle of 90 ° ± 20 °, is set to have a narrower groove width and a shallower groove depth than the circumferential groove and the lug groove. A narrow groove is formed, and a distance from the second corner portion measured on the bisector to the second narrow groove is set to 5 mm or more and 10 mm or less.

Next, the operation of the pneumatic tire according to claim 2 will be described.
If the pneumatic tire has a designation of the rotational direction, the narrow groove may be formed only on the outermost first corner side in the tread width direction on the kicking side of the block, but the pneumatic tire does not designate the rotational direction. In this case, if a narrow groove (second narrow groove) is formed in the outermost second corner in the tread width direction on the stepping side, the heel and toe wear of the block is possible in any rotation direction. Can be suppressed.

  The invention according to claim 3 is the pneumatic tire according to claim 1 or 2, wherein the first narrow groove and the second narrow groove have a groove width in a range of 2 to 4 mm. It is characterized by being set.

Next, the operation of the pneumatic tire according to claim 3 will be described.
If the groove width of the narrow groove is less than 2 mm, the narrow groove is closed at the time of ground contact, and a portion with low block rigidity (region on the corner side from the narrow groove) and a portion with high block rigidity (center side of the block from the narrow groove) are formed. Healing and toe wear may develop due to contact.

  On the other hand, if the groove width of the narrow groove exceeds 4 mm, the ground contact area of the block becomes too small, and on the contrary, there is a possibility of promoting uneven wear.

  According to a fourth aspect of the present invention, in the pneumatic tire according to any one of the first to third aspects, the first narrow groove and the second narrow groove have a groove depth of 2 to 4 mm. It is set within the range of.

Next, the operation of the pneumatic tire according to claim 4 will be described.
If the groove depth of the narrow groove is less than 2 mm, the narrow groove disappears before the progress of the heel and toe wear is suppressed.
On the other hand, if the groove depth of the narrow groove exceeds 4 mm, a portion having a low block rigidity (region on the corner side from the narrow groove) tends to be lost.

  As described above, since the pneumatic tire of the present invention has the above-described configuration, the tread width direction on the kick-out side of the block, particularly when the lateral force is applied, among the heel and toe wear generated in the block. It is possible to effectively suppress uneven wear that progresses obliquely inward from the corner side of the outermost end toward the stepping side of the block.

  Therefore, it is particularly effective to use the pneumatic tire of the present invention for the steered wheels, for example, in which the lateral force acts frequently among the wheels of the vehicle.

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, a tread 12 of a pneumatic tire (for example, tire size: 11R22.5) 10 according to an embodiment of the present invention includes a plurality of circumferential grooves 14 extending in the tire circumferential direction, and these A plurality of blocks 18 defined by a plurality of lug grooves 16 extending in a direction crossing the circumferential groove 14 are defined. In FIG. 1, the arrow A direction is the rotational direction of the pneumatic tire 10.

  The lug groove 16 of the present embodiment is inclined with respect to the tire width direction so that the tire equatorial plane CL side is closer to the tire rotation direction side than the tread end side, and the lug groove 16 on the right side of the tire equatorial plane CL and the left side The direction of inclination is opposite to that of the lug groove 16. Therefore, the block 18 of the present embodiment has a parallelogram in a tread plan view.

  As shown in FIG. 2, the block 18 includes a first side on the kick-out side (opposite to the arrow A direction) and on the first corner 18 </ b> A side on the outermost side in the tread width direction from the tire equatorial plane CL. It intersects with the bisector LA of the corner 18A at an angle θA of 90 ° ± 20 °, and the groove width is narrower than the circumferential groove 14 and the lug groove 16, and the groove depth is set shallower. A first narrow groove 22A is formed. In the present embodiment, the distance DA measured on the bisector LA from the first corner 18A to the first narrow groove 22A is set to 5 mm or more and 10 mm or less.

Each block 18 has a 90 ° angle with respect to the bisector LB of the second corner 18B on the outermost second corner 18B side on the tread width direction on the stepping side (arrow A direction side). A second narrow groove 22B is formed, which intersects at an angle of ± 20 °, is narrower than the circumferential groove 14 and the lug groove 16, and has a shallow groove depth. In the present embodiment, the distance DB measured on the bisector LB from the second corner 18B to the second narrow groove 22B is set to 5 mm or more and 10 mm or less.
Note that the first narrow groove 22A and the second narrow groove 22B are each connected to the block end (the circumferential groove 14 or the lug groove 16).

In this embodiment, the circumferential groove 14 has a groove width of 10.0 mm and a groove depth of 16.2 mm, and the lug groove 16 has a groove width of 9.0 mm and a groove depth of 16.2 mm.
Here, the groove width of the first narrow groove 22A and the second narrow groove 22B is preferably in the range of 2 to 4 mm.
The groove depths of the first narrow groove 22A and the second narrow groove 22B are preferably in the range of 2 to 4 mm.
Moreover, it is preferable that both ends of the first narrow groove 22A and the second narrow groove 22B are connected to the block edge (the circumferential groove 14 or the lug groove 16).

  In addition, as shown in FIGS. 3 (A) to 3 (C), the first narrow groove 22A and the second narrow groove 22B may have a rectangular shape, a substantially U-shaped shape, an inverted trapezoidal shape, etc. Other shapes may be used.

(Function)
Next, the effect | action of the pneumatic tire 10 of this embodiment is demonstrated.
For example, when the pneumatic tire 10 of the present embodiment is mounted on a vehicle and traveled, a force in the tire circumferential direction acts on the block 18 of the pneumatic tire 10, but during cornering, a tire lateral force ( Lateral force) also acts.
When the vehicle corners, among the treads 12 of the pneumatic tire 10 on the radially outer side of the turn, a large lateral force (from the vehicle outer side to the tire equator plane) is applied to the block 18 located on the radially outer side of the turn than the tire equator plane CL. (CL direction) acts.

  When the tire circumferential force and lateral force act on the block 18, the block 18 has a kick-out side and an oblique depression side (from the outermost corner side (first corner portion 18 </ b> A) in the tread width direction) ( Although partial wear tends to progress toward the block center side), this partial wear can be suppressed by forming the first narrow groove 22A as in the present embodiment.

  When the direction of the first narrow groove 22A deviates from 90 ° ± 20 ° with respect to the bisector LA, 3 of the triangular portion between the first corner 18A and the first narrow groove 22A. The angle of any one of the two corners becomes too small, and the lack of rigidity causes block missing.

Further, when the distance DA from the first corner portion 18A to the first narrow groove 22A is less than 5 mm, a portion having a low block rigidity (a triangular portion between the first corner portion 18A and the first narrow groove 22A). ) Is easily chipped.
On the other hand, if the distance DA from the first corner 18A to the first narrow groove 22A exceeds 10 mm, the distance from the first corner 18A to the first narrow groove 22A becomes too long, and the heel and The progress of toe wear cannot be suppressed.

In addition, when the groove width of the first narrow groove 22A is less than 2 mm, the groove is closed at the time of ground contact, and the portion having low block rigidity (a triangular portion between the first corner portion 18A and the first narrow groove 22A). There is a case where heel and toe wear develops due to contact between the portion having a high block rigidity (the block center side of the first narrow groove 22A).
On the other hand, when the groove width of the first narrow groove 22A exceeds 4 mm, the ground contact area of the block 18 becomes too small, and there is a possibility that the uneven wear is conversely promoted.

If the groove depth of the first narrow groove 22A is less than 2 mm, the first narrow groove 22A disappears before the progress of heel-and-toe wear is suppressed.
On the other hand, when the groove depth of the first narrow groove 22A exceeds 4 mm, a portion having a low block rigidity (a triangular portion between the first corner portion 18A and the first narrow groove 22A) tends to be lost.

  In the pneumatic tire 10 of the present embodiment, the second narrow groove 22B defined in the same manner as the first narrow groove 22A is formed on the stepping side and on the outermost corner side in the tread width direction. When the rotation direction is changed by rotation or the like (the direction opposite to the arrow A direction), the second narrow groove 22B is positioned on the kicking side and on the outermost corner side in the tread width direction, Similarly, the progress of heel and toe wear can be suppressed.

[Other Embodiments]
In the pneumatic tire 10 of the present embodiment, the first narrow groove 22A and the second narrow groove 22B are formed in the block 18 on the assumption that the rotation direction is changed by rotation or the like. Not limited to this, when the direction of the pneumatic tire 10 is designated, only the first narrow groove 22A may be formed in the block 18 (the second narrow groove 22B is not necessary). .

  In the above embodiment, the tread pattern is bilaterally symmetric. However, the present invention is not limited to this, and the tread pattern may be bilaterally asymmetric. The block shape is not limited to a parallelogram, and may be a square or a rectangle. Other polygons may be used. For example, when the block shape is a polygon having a pentagon or more, the first narrow groove 22A needs to be formed on the kicking side and on the outermost corner portion side in the tread width direction. Similarly, the second narrow groove 22B also needs to be formed on the stepping side and on the outermost corner side in the tread width direction.

  In addition, it is necessary to avoid forming a narrow groove on the corners other than the first and second corners because it causes new uneven wear.

実車試験の結果から、本発明の適用された実施例の空気入りタイヤは、ブロックの蹴り出し側のトレッド幅方向最外側の角部から摩耗し始めて、次第にブロックの踏み込み側に向かって斜め内側に偏摩耗が進展する形態のヒール・アンド・トゥ摩耗を効果的に抑制できていることが分かる。 (Test example)
In order to confirm the effect of the present invention, two types of pneumatic tires of the embodiment to which the present invention is applied and one type of conventional pneumatic tire are prepared, and an actual vehicle running test is performed to check heel and toe wear. A comparison was made.
The size of the pneumatic tire used for the test is 11R22.5, the rim width is 7.5 inches, and the internal pressure is 900 kPa. Further, the block shape is as shown in FIG. 1, and a narrow groove is formed in the tire block of the embodiment, and no narrow groove is formed in the tire block of the conventional example. The block has a circumferential length L of 43 mm, a width W of 36 mm, and a lug groove inclination angle θ (relative to the tread width direction) of 4 ° (see FIG. 2).
The test content in the actual vehicle was 80% high speed (80 km / h) and 20% low speed (30 km / h) during the test run, and the start and stop were repeated periodically.
Other tests are as follows.
Vehicle: 2D4 (a vehicle type comprising a steering shaft, a driving shaft, and a floating shaft, arranged in the order of a steering shaft on the front portion of the vehicle, and a driving shaft and a floating shaft in front of the rear portion)
Method: Mounting position fixed Contents: The progress width (distance) of heel-and-toe wear from the top of the block (first corner) when traveling at 20,000 km and 40,000 km with a tire mounted on the front shaft It was measured.
Table 1 below shows the dimensions of each part and the test results.

From the results of the actual vehicle test, the pneumatic tire of the example to which the present invention was applied began to wear from the outermost corner in the tread width direction on the kicking side of the block, and gradually inwardly toward the stepping side of the block. It can be seen that heel-and-toe wear in a form in which uneven wear develops can be effectively suppressed.

It is a top view of the tread of the pneumatic tire concerning one embodiment of the present invention. It is an enlarged plan view of a block. (A)-(C) are examples of the cross-sectional shape of a narrow groove, respectively.

Explanation of symbols

10 Pneumatic tire 12 Tread 14 Circumferential groove 16 Lug groove 18 Block 22A Narrow groove 22B Narrow groove

Claims (4)

A pneumatic tire comprising a tread having a plurality of blocks defined by a plurality of circumferential grooves extending in the circumferential direction and a plurality of lug grooves extending in a direction intersecting the circumferential groove,
At an angle of 90 ° ± 20 ° with respect to the bisector of the two sides constituting the first corner on the kicking side of the block and on the first corner on the outermost side in the tread width direction Forming a first narrow groove that intersects and is set to have a groove width narrower and a groove depth shallower than the circumferential groove and the lug groove;
A pneumatic tire, wherein a distance from the first corner portion measured on the bisector to the first narrow groove is set to 5 mm or more and 10 mm or less. Intersects the bisector of the two sides constituting the second corner at an angle of 90 ° ± 20 ° on the stepping side of the block and on the second corner on the outermost side in the tread width direction And forming a second narrow groove having a groove width narrower and a groove depth shallower than the circumferential groove and the lug groove,
The pneumatic tire according to claim 1, wherein a distance from the second corner portion measured on the bisector to the second narrow groove is set to 5 mm or more and 10 mm or less.   The pneumatic tire according to claim 1 or 2, wherein a groove width of the first narrow groove and the second narrow groove is set in a range of 2 to 4 mm.   The said 1st narrow groove and the said 2nd narrow groove are set in the range whose groove depth is 2-4 mm, The any one of Claims 1-3 characterized by the above-mentioned. Pneumatic tire.

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