JP2017105346A - Pneumatic tire - Google Patents

Abstract

A pneumatic tire capable of suppressing heel and toe wear while reducing pattern noise. A pneumatic tire (1) includes a plurality of blocks (5) partitioned by a plurality of main grooves (3) extending in a circumferential direction in a tread portion (2) and a plurality of lateral grooves (4) intersecting with the main grooves (3). The circumferential cross-section is tapered in the depth direction, and includes a plurality of width-direction grooves 10 extending in the width direction and partitioning the block 5 in the circumferential direction. It is provided so as to gradually decrease toward the part 51. [Selection] Figure 3

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 provided with a plurality of block portions partitioned 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, wherein the block portions have a circumferential cross section. Is tapered in the depth direction, and includes a plurality of width direction grooves extending in the width direction to partition the block portion in the circumferential direction, and the plurality of width direction grooves have a rigidity of the block portion at the stepped side edge. It is provided so that it may decrease gradually as it goes.

  According to the present invention, by providing a plurality of widthwise grooves so that the rigidity of the block portion gradually decreases toward the edge on the stepping side, the rigidity of the block portion is effectively reduced at the edge on the stepping side. However, the amount of reduction in rigidity can be gradually reduced toward the edge on the kick-out side. 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.

  Moreover, since the width direction groove | channel has the circumferential direction cross section tapering in a depth direction, the volume of a division part becomes small so that the block part is the surface side. This makes it easy to reduce the rigidity particularly on the surface side of the block portion, and it is easy to more suitably bend the surface of the block portion serving as the ground contact surface when stepped on.

  Moreover, by increasing the amount of reduction in the rigidity of the block portion on the stepping side, the stepping side is likely to be worn. 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, it is possible to reduce the impact sound at the time of ground contact while improving uneven wear resistance.

  It is preferable that the formation pitch in the circumferential direction of the plurality of widthwise grooves is set so as to gradually increase toward the edge side on the kicking side of the block portion.

  According to this configuration, since the volume of the partition portion of the block portion partitioned by the plurality of width direction grooves increases toward the edge on the kicking side, the rigidity of the block portion is greatly reduced on the stepping side. At the same time, the amount of reduction can be gradually reduced toward the edge on the kick-out side. Thereby, the impact sound at the time of stepping on can be reduced.

  Further, as the ground contact area of the partition portion becomes smaller toward the stepped side edge portion, the ground contact pressure increases on the stepped side, and therefore, wear easily occurs. As a result, since the amount of slip 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, it is possible to reduce the impact sound at the time of ground contact while improving uneven wear resistance.

  It is preferable that the groove depths of the plurality of the width direction grooves gradually decrease as they are located on the edge side on the kicking side.

  According to this configuration, since the volume of the partition portion of the block portion partitioned by the plurality of width direction grooves increases toward the edge on the kicking side, the rigidity of the block portion is greatly reduced on the stepping side. At the same time, the amount of reduction can be gradually reduced toward the edge on the kick-out side. Thereby, the impact sound at the time of stepping on can be reduced.

  The tire circumferential direction length L0 of the block portion and the length L1 from the stepped-side edge of the block portion to the widthwise groove located on the most kicked-out edge side of the block portion are 0. It is preferable to have a relationship of 3 ≦ L1 / L0 ≦ 0.75.

  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, it is possible to prevent the rigidity of the block portion 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 0.3, 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 0.75, the rigidity of the block portion tends to be excessively lowered, so that the operability is deteriorated.

  The height at the stepped side edge portion The height H0 of the block portion in the radial direction of the tire and the depth H1 of the widthwise groove located closest to the stepped side are 0.2 ≦ H1 / H0 ≦ 0.5. It is preferable to have.

  Here, the groove depth of the width direction groove means the length in the tire radial direction from the surface of the block portion to the groove bottom.

  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 0.5, the rigidity of the block portion tends to be excessively lowered, and 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 enlarged plan view of the block of FIG. The side view which looked at the block of FIG. 2 from the A direction. The side view of the block which concerns on the modification similar to FIG. The side view of the block which concerns on the further modification. The side view of the block concerning the further another modification. The side view of the block concerning the further another modification.

  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 plan view showing the block 5. As shown in FIG. 2, the block 5 is provided with a plurality of (for example, five) widthwise grooves 10 extending in the tire width direction. The formation pitch P in the tire circumferential direction of the plurality of widthwise grooves 10 is a kick that finally leaves the road surface from the stepped edge 51 that contacts the road surface first in the block 5 when the tire rotation direction is R. It gradually increases toward the edge 52 on the delivery side.

In addition, the formation pitch P in the circumferential direction of the width direction groove 10 means distances P2 to P5 between the center positions in the circumferential direction of the width direction grooves 10 adjacent to each other. Further, the width direction groove 10 1 located on the most leading side edge 51 _side, and each of the width direction groove 10 ₅ is located in the most trailing side edge 52 side, in the tire circumferential direction on both sides of the block 5 The distance from the wall surface is also shown as formation pitches P1 and P6.

  Moreover, as shown in FIG. 3 as viewed in the direction of arrow A in FIG. Further, the plurality of width direction grooves 10 are formed in substantially the same shape, and the groove walls 11 and 12 are inclined and extended so as to be closer to each other toward the inner side in the tire radial direction, and between the groove walls 11 and 12. Are formed so that the interval in the tire circumferential direction is tapered in the depth direction. In other words, the width direction groove 10 is formed so that the groove width in the tire circumferential direction gradually decreases as it goes inward in the tire radial direction. The groove bottom 13 of the width direction groove 10 is formed in an edge shape in which the opposing groove walls 11 and 12 intersect at an acute angle.

As described above, the block 5 has a plurality of widthwise grooves 10 that taper in the depth direction in the circumferential cross section and extend in the tire width direction, and the formation pitch P in the tire circumferential direction is kicked out from the edge 51 on the stepping side. It is formed so as to gradually increase toward the side edge portion 52. As a result, the block 5 is partitioned into a plurality of partition portions 50 ₁ to 50 ₆ in the circumferential direction by the plurality of widthwise grooves 10 ₁ to 10 ₅ , and these partition portions 50 ₁ to 50 ₆ are edges on the stepping side. As it goes to the part 51 side, as a result of the volume becoming smaller, the rigidity becomes smaller.

  That is, by forming the plurality of widthwise grooves 10 so that the formation pitch P in the tire circumferential direction gradually increases toward the kick-out edge 52, the rigidity of the block 5 increases toward the tread edge 51. It is possible to gradually reduce the rigidity of the block 5, thereby gradually reducing the rigidity reduction amount toward the kick-out edge 52 side while effectively reducing the rigidity of the block 5 on the edge 51 side. Can do. As a result, when stepping on, the vicinity of the stepped-side edge 51 can be appropriately bent to absorb the impact, so that the impact sound when stepping on can be reduced.

  Moreover, since the width direction groove | channel 10 has the circumferential direction cross-section tapering in the depth direction, the volume of the division part 50 becomes small toward the grounding surface 53 side of the block 5. This makes it easy to reduce the rigidity particularly on the ground contact surface 53 side of the block 5, and to easily deflect the ground contact surface 53 of the block 5 more suitably when stepped on.

  In addition, by increasing the amount of reduction in the rigidity of the block 5 at the stepped side edge 51, the stepped side edge 51 side is easily worn. As a result, the wear difference with the edge 52 on the kick-out side, which is relatively easy to wear due to the large amount of slip, is reduced, and heel and toe wear is suppressed, thereby improving uneven wear resistance. To do. Therefore, it is possible to reduce the impact sound at the time of ground contact while improving uneven wear resistance.

  In addition, the formation pitches P1 to P6 of the plurality of width direction grooves 10 may be set so as to increase linearly (for example, expressed by a linear function P (i) = α × i + β). As a result, the amount of reduction in the rigidity of the block 5 can be linearly reduced as it goes toward the kick-out edge 52, so that it is possible to prevent the rigidity from changing suddenly, and the impact sound at the time of ground contact Reduction and improvement in uneven wear resistance are preferably realized.

Further, as shown in FIG. 2, the tire circumferential direction length L0 of the block, to the widthwise grooves 10 ₅ disposed at the edge 52 side of the most trailing side from the leading side edge 51 of the block length L1 Are preferably formed so as to have a relationship of 0.3 ≦ L1 / L0 ≦ 0.75.

  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 0.3, the reduction amount of the striking sound at the time of depressing is reduced because the margin for reducing the rigidity on the side of the stepped side edge 51 of the block 5 is small. On the other hand, when L1 / L0 is larger than 0.75, the rigidity of the block 5 tends to be excessively lowered, so that the operability is deteriorated.

  Further, as shown in FIG. 3, the tire radial direction height H0 and the width direction groove 10 groove depth H1 at the stepped side edge 51 of the block 5 are preferably 0.2 ≦ H1 / H0. The width direction groove 10 is formed so as to have a relationship of ≦ 0.5. Further, the groove depth H1 at the stepped side edge 51 of the width direction 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 amount of reduction in the striking sound at the time of depressing is reduced because the margin for reducing the rigidity at the stepped edge 51 of the block 5 is small. On the other hand, when H1 / H0 is larger than 0.5, 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 stepped side edge 51 of the width direction groove 10 is shallower than 2 mm, the rigidity of the block 5 cannot be sufficiently reduced.

  In the said embodiment, although the several width direction groove | channel 10 was made into the substantially identical shape, you may vary groove width not only in this. For example, as shown in FIG. 4, the groove width may be gradually increased toward the kick-out side edge 52, and although not illustrated, the groove width is increased toward the stepping-side edge 51 side. You may make it reduce gradually.

  Moreover, in the said embodiment, although the formation pitch P of the several width direction groove | channel 10 was changed, not only this but the formation pitch P is good also as substantially constant. In this case, as shown in FIG. 5, the groove depth of the width direction groove 10 is formed so as to gradually decrease toward the edge portion 52 side on the kicking side. As a result, while the formation pitch P of the plurality of width direction grooves 10 is made substantially constant, the rigidity of the block 5 is reduced on the edge 51 side on the stepping side, but as it goes toward the edge 52 side on the kicking side. The amount of reduction in rigidity can be gradually reduced.

  In addition, you may set the groove bottom 13 of the some circumferential groove | channel 10 along the inclination straight line S extended toward a tire radial direction outer side as it goes to the edge part 52 side on the kicking side. As a result, the amount of reduction in the rigidity of the block 5 can be linearly reduced as it goes toward the kick-out edge 52, so that it is possible to prevent the rigidity from changing suddenly, and the impact sound at the time of ground contact Reduction and improvement in uneven wear resistance are preferably realized.

  Moreover, in the said embodiment, although the groove bottom 13 of the width direction groove | channel 10 was made into edge shape, as shown in FIG. 6, you may form in R shape, and, thereby, the stress in the groove bottom 13 of the width direction groove | channel 10 Concentration can be suppressed and crack resistance can be improved.

  In addition, as shown in FIG. 7, the plurality of widthwise grooves 10 are gradually increased as the formation pitch P is moved toward the kick-out edge 52, and the groove depth is gradually decreased as it is moved toward the kick-out edge 52. You may make it make it. Thus, while the rigidity of the block 5 is suitably reduced on the edge 51 side on the stepping side, the amount of reduction in rigidity can be gradually reduced toward the edge 52 side on the kicking 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.

A width direction groove is not formed in the block of the pneumatic tire of Comparative Example 1.

  As shown in FIG. 3, in the block of the pneumatic tire of Example 1, a plurality of widthwise grooves 10 extending in the tire width direction have substantially the same shape (that is, the same depth) and a formation pitch P in the tire circumferential direction. Is formed so as to gradually increase toward the edge 52 on the kick-out side.

  As shown in FIG. 5, in the block of the pneumatic tire of Example 2, a plurality of widthwise grooves 10 extending in the tire width direction kick the groove depth while keeping the formation pitch P in the tire circumferential direction substantially constant. It forms so that it may reduce gradually as it goes to the edge part 52 side of the delivery side.

  As shown in FIG. 7, in the block of the pneumatic tire of Example 3, a plurality of widthwise grooves 10 extending in the tire width direction has a formation pitch P in the tire circumferential direction toward the edge 52 on the kicking side. The groove depth is gradually increased, and the groove depth is gradually decreased toward the edge 52 on the kicking side.

  A pneumatic tire according to Comparative Example 1 and Examples 1 to 3 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 tires according to Examples 1 to 3 in which the plurality of widthwise grooves 10 are formed, the noise performance is superior to that of Comparative Example 1. This is because the rigidity of the block 5 is suitably reduced by the plurality of widthwise grooves 10, particularly on the edge 51 side on the stepping side, so that the shock can be suitably absorbed by bending at the time of ground contact. This is considered to be because the impact sound at the time of grounding is reduced.

  Further, the pneumatic tires according to Examples 1 to 3 are superior to Comparative Example 1 in terms of wear resistance. This is because, in any of the pneumatic tires of Examples 1 to 3, the plurality of widthwise grooves 10 gradually decrease the rigidity reduction amount as the rigidity of the block 5 moves toward the edge 52 side on the kicking side. Therefore, the rigidity of the block 5 is not excessively reduced. As a result, the block 5 is easily worn on the edge 51 side on the stepping side. As a result, the wear difference with the edge 52 side on the kick-out side that is relatively easy to wear due to a large amount of slip is reduced. This is considered to be because uneven wear resistance is improved because heel and toe wear is suppressed.

  The pneumatic tire according to Example 3 was superior in both noise performance and uneven wear resistance as compared with Examples 1 and 2. In Example 3, it is more preferable by changing both the formation pitch P and the groove depth in the tire circumferential direction of the plurality of widthwise grooves 10 toward the edge 52 side on the kicking side. This is considered to be because the rigidity reduction amount on the kick-out edge 52 side can be gradually decreased while the rigidity on the step-edge edge 51 side is reduced.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Main groove 4 Lateral groove 5 Block 10 Width direction groove 51 Edge part on stepping side 52 Edge part on kicking side 53 Grounding surface

Claims (5)

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 circumferential cross section is tapered in the depth direction, and includes a plurality of width direction grooves extending in the width direction and partitioning the block portion in the circumferential direction,
The plurality of widthwise grooves are provided in a pneumatic tire such that the rigidity of the block portion gradually decreases as it goes toward the edge on the stepping side.   2. The pneumatic tire according to claim 1, wherein a formation pitch in the circumferential direction of the plurality of widthwise grooves is set so as to gradually increase toward an edge side on a kicking side of the block portion.   3. The pneumatic tire according to claim 1, wherein the groove depths of the plurality of widthwise grooves are gradually decreased toward the edge side on the kick-out side.   The tire circumferential direction length L0 of the block portion and the length L1 from the stepped-side edge of the block portion to the widthwise groove located on the most kicked-out edge side of the block portion are 0. The pneumatic tire according to any one of claims 1 to 3, wherein the pneumatic tire has a relationship of 3≤L1 / L0≤0.75.   The height at the stepped side edge portion The height H0 of the block portion in the radial direction of the tire and the depth H1 of the widthwise groove located closest to the stepped side are 0.2 ≦ H1 / H0 ≦ 0.5. The pneumatic tire according to any one of claims 1 to 4, which has

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