JP2017105345A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of reducing heel and toe wear while reducing a pattern noise.SOLUTION: There is provided a pneumatic tire which comprises a plurality main grooves 3 extending in a tread part 2 in a circumferential direction and a plurality of blocks 5 partitioned by a plurality of lateral grooves 4 crossing the main grooves, wherein the blocks 5 have at least one circumferential groove 10 which extends from an edge part 51 on the treading side to the circumferential direction, with the width direction cross section being tapered in the depth direction, and the depth and width of the circumferential groove 10 are gradually reduced toward an edge part 52 on the kicking-side.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire.

  Conventionally, it is known that a pneumatic tire having a block pattern is accompanied by occurrence of uneven wear and pattern noise. As uneven wear due to the block pattern, heel & toe wear is known. Also, as pattern noise, when the block touches the road surface due to rolling of the tire, the impact sound caused by the stepping side area of the block portion hitting the road surface is based on the formation pitch of the block portion and the vehicle speed. Occurs at different frequencies.

  Generally, it is known that the wear amount is determined based on the contact pressure and the slip amount. When the block is separated from the road surface, the amount of slippage in the kick-out area is large, and as a result, the kick-out area is more likely to wear than the step-on area, so that The difference in the amount of wear from the delivery side increases, resulting in heel and toe wear.

  In Patent Documents 1 and 2, by providing a raised portion on the ground contact surface of the block portion, the ground pressure at the edge portion and the central portion of the block portion is reduced, whereby the ground contact pressure of the block portion is substantially uniform on the ground contact surface. It is disclosed to suppress the occurrence of uneven wear.

Special table 2004-517772 gazette JP 2000-071719 A

  In the pneumatic tires of Patent Documents 1 and 2, the uneven wear of the edge and center of the block is suppressed, but the wear difference between the edge on the stepping side and the edge on the kicking side, that is, the heel & It does not suppress toe wear. Further, pattern noise cannot be reduced.

  This invention is made in view of the said subject, and it aims at obtaining the pneumatic tire which can suppress heel & toe wear, reducing pattern noise.

  The present invention is a pneumatic tire including a plurality of block portions partitioned by a plurality of main grooves extending in the circumferential direction in the tread portion and a plurality of lateral grooves intersecting the tread portion, wherein the block portions are cross-sectional in the width direction. Is tapered in the depth direction and includes at least one circumferential groove extending in the circumferential direction from the edge on the stepping side, and the groove depth and groove width of the circumferential groove gradually decrease toward the kick-out edge. It is designed to do this.

  Here, the groove depth of the circumferential groove means the length in the tire radial direction from the surface of the block portion to the groove bottom. Further, the groove width of the circumferential groove means the length of the groove in the tire width direction. In the present invention, the circumferential groove is tapered in the depth direction in the cross section in the width direction. It gradually decreases as it goes in the direction.

  According to the present invention, the circumferential groove that the groove width and groove depth gradually decrease toward the kicking-out edge portion effectively reduces the rigidity of the block portion at the stepping-side (toe side) edge portion. However, the amount of reduction in rigidity can be gradually reduced toward the edge on the kicking side (heel side), and the rigidity of the block portion does not decrease excessively. As a result, at the time of depression, the vicinity of the edge on the depression side can be appropriately bent to absorb the impact. Therefore, the impact sound at the time of stepping on can be reduced.

  In addition, since the circumferential groove has a widthwise cross section that tapers in the depth direction, the block portion has a smaller volume of a partition portion partitioned by the circumferential groove toward the surface side. For this reason, it is easy to reduce rigidity especially in the surface side of a block part, and when stepping on, the surface of the block part used as a grounding surface is more likely to bend more suitably.

  In addition, since the groove width of the circumferential groove gradually decreases toward the edge on the kicking side, the ground contact area of the block portion decreases toward the stepping side. As a result, on the stepping side of the block portion, the contact pressure is likely to be worn by increasing the contact pressure. As a result, since the slip amount is large, the wear difference from the kicking side, which is relatively easy to wear, is reduced, and heel and toe wear is suppressed, so that uneven wear resistance is improved.

  It is preferable that the tire circumferential length L0 of the block portion and the tire circumferential length L1 of the circumferential groove have a relationship of 0.1 ≦ L1 / L0 ≦ 0.5.

  According to this configuration, it is possible to suppress a decrease on the kicking side while appropriately reducing the rigidity of the block portion on the stepping side. Thereby, while reducing the impact sound at the time of depressing, it is possible to prevent the rigidity of the block portion from being excessively lowered and suppress the deterioration of the operability.

  When L1 / L0 is smaller than 0.1, the reduction amount of the striking sound at the time of depressing is reduced because the rigidity reduction margin on the depressing side of the block portion is small. On the other hand, when L1 / L0 is larger than 0.5, the rigidity of the block portion tends to be excessively lowered, so that the operability is deteriorated.

  The width W0 of the block portion in the tire width direction at the stepped-side edge and the sum W of the lengths in the tire width direction of the contact surfaces of the block portions of the plurality of circumferential grooves are 0.2 ≦ W. It is preferable to have a relationship of /W0≦1.0.

  According to this configuration, the rigidity of the block portion can be appropriately reduced on the stepping side. When W / W0 is smaller than 0.2, the reduction amount of the striking sound at the time of stepping down is reduced because the rigidity reduction margin on the stepping side of the block portion is small.

  It is preferable that a tire radial height H0 of the block portion and a groove depth H1 of the circumferential groove have a relationship of 0.2 ≦ H1 / H0 ≦ 1.0 in the edge portion on the stepping side. .

  According to this configuration, the rigidity of the block portion can be appropriately reduced on the stepping side. When H1 / H0 is smaller than 0.2, the reduction cost of the striking sound at the time of stepping down is reduced because the reduction in rigidity on the stepping side of the block portion is small. On the other hand, when H1 / H0 is larger than 1.0, the rigidity of the block portion tends to be excessively lowered, so that the operability is deteriorated.

  The pneumatic tire according to the present invention can suppress heel and toe wear while reducing pattern noise.

The top view which lowers and shows the tread pattern formed in the tread part of the pneumatic tire concerning one embodiment of the present invention. The expansion perspective view of the block of FIG. The block diagram of FIG. Sectional drawing in the IV-IV line of FIG. Sectional drawing similar to FIG. 3 which shows the modification of a circumferential groove | channel. Sectional drawing similar to FIG. 3 which shows the other modification of the circumferential groove | channel. Sectional drawing similar to FIG. 3 which shows the further another modification of a circumferential direction groove | channel. Sectional drawing similar to FIG. 3 which shows the further another modification of a circumferential direction groove | channel. The expansion perspective view of the block concerning the comparative example 1. FIG. The expansion perspective view of the block concerning the comparative example 2. FIG. FIG. 3 is an enlarged perspective view of a block according to the first embodiment.

  Embodiments according to the present invention will be described below with reference to the accompanying drawings. In addition, the following description is only illustrations essentially and does not intend restrict | limiting this invention, its application thing, or its use. Further, the drawings are schematic, and the ratio of each dimension is different from the actual one.

  FIG. 1 is a plan view showing a developed tread portion 2 of a pneumatic tire 1 according to an embodiment of the present invention. As shown in FIG. 1, the tread portion 2 is formed with a plurality of main grooves 3 extending in the tire circumferential direction and a plurality of lateral grooves 4 extending in the tire width direction intersecting the main grooves 3. A plurality of blocks (block portions) 5 are defined by the main grooves 3 and the lateral grooves 4.

  Here, in the present invention, extending in the tire circumferential direction means not only when extending in parallel to the tire circumferential direction, but also in a zigzag shape or inclined with respect to the tire circumferential direction and extending in the tire circumferential direction. Also included. Similarly, the term “extending in the tire width direction” includes not only the case of extending in the tire width direction but also the case of extending in the tire width direction in a zigzag shape or inclined with respect to the tire width direction.

  FIG. 2 is an enlarged perspective view showing the block 5. As shown in FIG. 2, the block 5 is provided with two circumferential grooves 10 extending in the tire circumferential direction. When the tire rotation direction is assumed to be R, the circumferential groove 10 extends from the stepped-side edge 51 that first contacts the road surface of the block 5 toward the kicked-side edge 52 that finally leaves the road surface. Extending in the direction. The circumferential groove 10 is formed such that the groove width in the tire width direction gradually decreases toward the kick-out side edge 52.

  More specifically, the groove walls 11 and 12 that constitute the circumferential groove 10 are formed in a parabolic shape with the edge 51 on the stepping side as the origin and toward the edge 52 on the kick-out side. As a result, the block 5 is partitioned by the circumferential groove 10 into a mountain shape with the stepped-side edge 51 side convex in plan view.

  FIG. 3 is a view as seen from an arrow A in FIG. 2 and shows the block 5 as viewed from the stepping side toward the kicking side. As shown in FIG. 3, the groove walls 11, 12 of the circumferential groove 10 extend in the tire radial inner diameter side in a parabolic shape convex upward, and the interval in the tire width direction between the groove walls 11, 12 is It is formed to taper in the depth direction. In other words, the circumferential groove 10 is formed such that the groove width in the tire width direction gradually decreases toward the inner side in the tire radial direction. The groove bottom 13 of the circumferential groove 10 is formed in an edge shape in which the opposed groove walls 11 and 12 intersect at an acute angle.

The block 5 has a form in which both side portions in the tire width direction are cut out by the chamfered portion 20, and thereby, in the view of the arrow A in FIG. 2 shown in FIG. 3, the three peaks in which the block 5 protrudes upward. The parts 50 ₁ , 50 ₂ , and 50 ₃ are formed. The chamfered portion 20 preferably has one side when the circumferential groove 10 is bisected in the tire width direction so that the crests 50 ₁ and 50 ₃ located on both sides in the tire width direction are axisymmetric in the tire width direction. It has the same shape.

  FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. 2 and shows a cross-sectional view along the center of the circumferential groove 10 in the tire width direction. As shown in FIG. 4, the circumferential groove 10 is formed such that the groove depth in the tire radial direction gradually decreases toward the kick-out edge 52, and the kick-out edge 52 includes It does not reach and terminates in the ground contact surface 53 of the block 5.

  As described above, the block 5 includes two circumferential grooves 10 that taper in the depth direction in the cross section in the width direction and extend in the circumferential direction from the stepping-side edge 51 toward the kick-out edge 52. In addition, the groove width and groove depth of the circumferential groove 10 are gradually decreased toward the edge 52 on the kick-out side.

  In other words, the circumferential groove 10 whose groove width and groove depth gradually decrease toward the kick-out edge 52 reduces the rigidity of the block 5 effectively on the step-side edge 51 side while kicking. The amount of reduction in rigidity can be gradually reduced toward the edge 52 on the delivery side. As a result, at the time of depression, the vicinity of the edge 51 on the depression side can be appropriately bent to absorb the impact. Therefore, the impact sound at the time of stepping on can be reduced.

  Further, since the circumferential groove 10 has a cross section in the width direction that tapers in the depth direction, the block 5 has a smaller volume of a partition portion partitioned by the circumferential groove 10 toward the ground surface 53 side. For this reason, it is easy to reduce rigidity especially in the grounding surface 53 side of the block 5, and it is easy to bend the grounding surface 53 of the block 5 more suitably at the time of stepping.

  Moreover, the groove width of the circumferential groove 10 gradually decreases toward the kick-out edge 52, in other words, the groove width increases toward the step-side edge 51. That is, since the contact area of the block 5 decreases toward the stepping side, the block 5 is easily worn by increasing the contact pressure on the stepping side of the block 5. As a result, since the slip amount is large, the wear difference from the kicking side, which is relatively easy to wear, is reduced, and heel and toe wear is suppressed, so that uneven wear resistance is improved. Therefore, according to the pneumatic tire 1 which concerns on this embodiment, the impact sound at the time of grounding can be reduced, improving uneven wear resistance.

  As shown in FIG. 3, the total width W of the tire width direction length W0 at the stepped side edge 51 of the block 5 and the tire width direction length at the ground contact surface 53 of the block 5 of the circumferential groove 10 and the chamfered portion 20. (That is, the sum of the groove widths W11 and W12 of the circumferential groove 10 and the widths W21 and W22 of the chamfered portion 20) preferably has a relationship of 0.2 ≦ W / W0 ≦ 1.0. Directional grooves 10 are formed.

  Thereby, the rigidity of the block 5 can be moderately reduced on the stepping side. When W / W0 is smaller than 0.2, the amount of reduction in the striking sound at the time of stepping down is reduced because the margin for reducing the rigidity at the stepping side edge 51 side of the block 5 is small.

  Also, as shown in FIG. 4, the tire circumferential length L0 of the block 5 and the tire circumferential length L1 of the circumferential groove 10 are preferably in a relationship of 0.1 ≦ L1 / L0 ≦ 0.5. A circumferential groove 10 is formed to have

  Accordingly, it is possible to suppress a decrease in the kick-out side edge 52 side while appropriately reducing the rigidity of the block 5 on the step-up side edge part 51 side. Thereby, it is possible to prevent the rigidity of the block 5 from being excessively lowered and reduce the deterioration of the operability while reducing the impact sound at the time of depressing. When L1 / L0 is smaller than 0.1, the reduction amount of the rigidity at the stepping side of the block 5 is small, so that the amount of reduction in the striking sound at the time of stepping is reduced. On the other hand, when L1 / L0 is larger than 0.5, the rigidity of the block 5 tends to be excessively lowered, so that the operability is deteriorated.

  Further, the tire radial direction height H0 and the groove depth H1 of the circumferential groove 10 at the stepped side edge 51 of the block 5 preferably have a relationship of 0.2 ≦ H1 / H0 ≦ 1.0. A circumferential groove 10 is formed so as to have. Further, the groove depth H1 at the edge 51 on the stepping side of the circumferential groove 10 is at least 2 mm or more.

  As a result, the rigidity of the block 5 can be appropriately reduced on the edge 51 side on the stepping side. When H1 / H0 is smaller than 0.2, the reduction amount of the striking sound at the time of depressing is reduced because the margin for reducing the rigidity on the depressing side edge 51 side of the block 5 is small. On the other hand, when H1 / H0 is larger than 1.0, the rigidity of the block 5 tends to be excessively lowered, so that the operability is deteriorated. Moreover, if the groove depth H1 at the edge 51 on the step-in side of the circumferential groove 10 is shallower than 2 mm, the rigidity of the block 5 cannot be sufficiently reduced.

  Preferably, the groove bottom 13 of the circumferential groove 10 is formed to extend linearly so that the groove depth gradually decreases toward the kick-out edge 52. Thereby, the rigidity of the block 5 by the circumferential groove 10 can be smoothly reduced without changing abruptly from the step-side edge 51 toward the kick-out edge 52. Thereby, the occurrence of uneven wear can be suppressed. Further, the groove bottom 13 may be formed so as to be curved in a smooth curved shape as long as the groove depth of the circumferential groove 10 is gradually reduced.

In the said embodiment, as shown in FIG. 3, the groove walls 11 and 12 of the circumferential groove | channel 10 are formed in the parabola shape which protrudes on the tire radial direction outer side, and, thereby, the block 5 is made into the edge part 51 by the side of depression. In FIG. 3, the groove portions 13 were divided into three peak portions 50 ₁ , 50 ₂ , 50 ₃ and the groove bottom 13 was formed in an edge shape. On the other hand, as shown in FIG. 5A, the groove bottom 13 of the circumferential groove 10 may be formed in an R shape, and the groove walls 11 and 12 of the circumferential groove 10 are tires as shown in FIG. 5B. You may form in the shape of a parabola which becomes convex on the radial inside. By forming the groove bottom 13 in an R shape, stress concentration at the groove bottom 13 of the circumferential groove 10 can be suppressed, and crack resistance can be improved.

  Further, the groove walls 11 and 12 of the circumferential groove 10 may be formed in a straight line as shown in FIG. 5C, and the groove walls 11 and 12 of the circumferential groove 10 are formed in a plurality of straight lines as shown in FIG. 5D. You may comprise from a part. Thereby, the rigidity of the block 5 can be linearly changed in the tire radial direction.

  In the above embodiment, the case where two circumferential grooves 10 are provided has been described as an example. However, the present invention is not limited to this, and at least one groove may be provided. That is, the block 5 is divided into at least two peak portions by at least one circumferential groove 10 and chamfered portions 20 on both sides in the tire width direction. In addition, it is preferable to form a peak part 2-10. If the number of peaks is greater than 10, the rigidity of the block 5 is excessively lowered, and the handling and wear resistance are deteriorated.

  Further, the chamfered portion 20 is not necessarily required. When the chamfered portion 20 is not formed, the total sum of the groove widths of the plurality of circumferential grooves 10 is set as W, as described above, the length W0 of the block 5 in the tire width direction. The circumferential groove 10 may be formed so that the relationship with the relationship preferably satisfies 0.2 ≦ W / W0 ≦ 1.0.

  Moreover, in the said embodiment, although the groove walls 11 and 12 of the circumferential groove | channel 10 were formed on the parabola which protrudes in the edge part 51 side by the side of depression in planar view, it does not restrict to this and forms in linear form. It suffices as long as the groove width gradually decreases toward the edge 52 on the kick-out side.

  Evaluation tests of noise and uneven wear resistance were performed on the pneumatic tires of Comparative Examples 1 and 2 and Example 1 shown in Table 1 below.

  As shown to FIG. 6A, the circumferential groove | channel is not formed in the block 105 of the pneumatic tire of the comparative example 1. FIG.

As shown in FIG. 6B, the block 205 of the pneumatic tire of Comparative Example 2 has one circumferential groove 210 at the center in the tire width direction and chamfered portions 220 at both sides in the tire width direction. Thereby, it is divided into two peak parts 250 ₁ and 250 ₂ . The circumferential groove 210 of Comparative Example 2 has a cross-section in the width direction that tapers in the depth direction, extends in the tire circumferential direction in the block 205, and has a constant depth from the step-side edge 251 to the kick-out edge 252. It is formed to have.

As shown in FIG. 6C, the block 5 of the pneumatic tire of Example 1 is formed with one circumferential groove 10 at the center in the tire width direction and chamfered portions 20 at both sides in the tire width direction. Thereby, it is divided into two peak parts 50 ₁ and 50 ₂ . In the circumferential groove 10 of the first embodiment, the cross section in the width direction tapers in the depth direction, and the groove width and the groove depth gradually decrease from the stepped-side edge 51 to the kick-out edge 52 of the block 5. It is formed to do.

  A pneumatic tire according to Comparative Examples 1 and 2 and Example 1 having a tire size of 195 / 65R15 is mounted on a 15-inch 6J rim and an internal pressure of 220 kPa is applied, and a noise test and an uneven wear resistance test are performed, respectively. did.

  In the noise evaluation test, a single tire stand test was performed, and the O.D. value when running at a speed of 80 km / h with a load of 500 kgf. A. Level was measured. The performance of the remaining Comparative Example 2 and Example 1 is indexed with the case of Comparative Example 1 being 100, and the lower the index, the better the noise performance.

  In the evaluation test of uneven wear resistance, a drum wear test is performed, and the amount of wear in the stepping-side region (near the stepping-side edge 51) and the amount of wear in the kicking-out region (near the kicking-side edge 52) are calculated. The difference was measured as the toe heel amount. The performance of the remaining Comparative Examples 2 and 1 is indexed with the case of Comparative Example 1 being 100, and the higher the index, the better the uneven wear resistance performance.

  In the pneumatic tire according to Comparative Example 2 and Example 1 in which the circumferential grooves 10 and 210 are formed, the noise performance is superior to that of Comparative Example 1. This is because the rigidity of the blocks 5 and 205 is reduced by the circumferential grooves 10 and 210, so that the impact can be suitably absorbed by the bending at the time of grounding, thereby reducing the impact sound at the time of grounding. It is thought that it is because.

  Further, the abrasion resistance of Comparative Example 2 is inferior to that of Comparative Example 1, and Example 1 is superior. In Comparative Example 2, since the circumferential groove 210 is formed at a constant depth over the tire circumferential direction of the block 205, the rigidity of the block 205 is excessively lowered, and wear resistance is deteriorated. It is considered that the property was inferior to that of Comparative Example 1.

  In Example 1, since the circumferential groove 10 is formed so that the groove width and the groove depth gradually decrease from the step-side edge 51 toward the kick-out side edge 52, the step-side edge While the rigidity is lowered on the part 51 side, the rigidity is not excessively lowered on the edge part 52 side on the kicking side. For this reason, by increasing the contact pressure by reducing the contact area on the stepped side edge portion 51 side and making it easy to wear, the difference in wear amount from the kicking side that is easily worn due to a large amount of slip has been reduced. it is conceivable that.

Edge 53 ground plane 1 pneumatic tire 2 tread portion 3 main groove 4 transverse grooves 5 blocks 10 circumferential groove 20 chamfer 50 _{1-50 3} crest of 51 leading side edge 52 trailing side

Claims (4)

A pneumatic tire provided with a plurality of block portions defined by a plurality of main grooves extending in the circumferential direction of the tread portion and a plurality of lateral grooves intersecting with the main grooves,
The block part is
The cross section in the width direction tapers in the depth direction, and includes at least one circumferential groove extending in the circumferential direction from the edge on the stepping side;
A pneumatic tire in which the groove depth and the groove width of the circumferential groove gradually decrease toward the edge on the kick-out side.   The pneumatic according to claim 1, wherein the tire circumferential length L0 of the block portion and the tire circumferential length L1 of the circumferential groove have a relationship of 0.1 ≦ L1 / L0 ≦ 0.5. tire.   The width W0 of the block portion in the tire width direction at the stepped-side edge and the sum W of the lengths in the tire width direction of the contact surfaces of the block portions of the plurality of circumferential grooves are 0.2 ≦ W. The pneumatic tire according to claim 1, wherein the pneumatic tire has a relationship of /W0≦1.0.   The tire radial direction height H0 of the block portion and the groove depth H1 of the circumferential groove in the stepped-side edge portion have a relationship of 0.2 ≦ H1 / H0 ≦ 1.0. The pneumatic tire according to any one of claims 1 to 3.

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