JP4362061B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire for use in an automobile traveling on a snowy road, and more particularly to a pneumatic tire with improved performance on snow.

Conventionally, when a pneumatic tire for winter travels on a snowy road, the tire slips on the snowy road without being able to grip the snowy road. In order to improve acceleration / braking performance on snowy roads and on-snow maneuvering stability, the tire tread pattern has been designed to have a sipe. Even if the horizontal sipe is increased to increase the horizontal sipe or the vertical sipe is appropriately provided, the lateral edge component cannot be secured, and the block rigidity is lowered, so there is a problem that the steering stability cannot be secured, and acceleration / braking on snow The current situation is that there is a limit to achieving both stability and snow handling stability.
JP 2001-191739 A Japanese Patent Laid-Open No. 2003-104012 JP-A-8-169212 JP-A-8-230417

  Therefore, the object of the present invention is to devise the sipe shape of the tread pattern and to provide vertical and horizontal sipe appropriately to ensure vertical and horizontal edge components and block rigidity, as well as snow acceleration and braking performance as well as snow handling stability. An object of the present invention is to provide a pneumatic tire that also improves the tire performance.

  In order to solve the above-mentioned problems, the present invention provides a pneumatic tire having a plurality of blocks defined by rib grooves extending in the tire circumferential direction and lug grooves extending in the tire width direction on the tread. The sipe is a horizontal sipe that is substantially parallel to the lug groove provided for each block, and a vertical sipe that is substantially parallel to the rib groove. The horizontal sipe is open to at least one rib groove on both sides of the block. The vertical sipe is a pneumatic tire having an opening only in one of the lug grooves on both sides of the block. Here, “substantially parallel” means within ± 10 ° from the parallel state. This is because even a sipe designed parallel to the lug groove or rib groove may be displaced to about ± 10 ° due to manufacturing errors during vulcanization molding.

  By providing the vertical sipe and the horizontal sipe in this way, both the vertical and horizontal edge components and the block rigidity can be secured, and in particular, the block rigidity against the horizontal input can be increased by making the vertical sipe a one-side open sipe. . Therefore, the tire can be improved not only in snow acceleration / braking performance but also in snow handling stability.

  In the above invention, the horizontal sipe may be opened only in one of the rib grooves on both sides of the block. By setting both the horizontal sipe and the vertical sipe to one side open sipe, it is possible to increase the block rigidity with respect to not only the lateral input but also the front / rear input and further improve the steering stability on snow.

  In the above invention, it is preferable that the plurality of horizontal sipes open alternately in the rib grooves on both sides of the block, and the plurality of vertical sipes open alternately in the lug grooves on both sides of the block. As described above, if the vertical and horizontal sipes are alternately opened in the lug grooves and rib grooves on both sides of the block, the block has block rigidity from any direction.

  In the above invention, in the block, the horizontal sipe and the vertical sipe intersect each other, and a small block surrounded by the sipe at the center of the block may be formed. In this way, the horizontal sipe and the vertical sipe intersect to form a small block surrounded by the sipe at the center of the block, so that the small block surrounded by the sipe can be freely deformed near the center of the block. Regardless of the edge effect.

  In the above invention, in the block, the deepest portion of the horizontal sipe can be deeper than the deepest portion of the vertical sipe. Thus, by making the deepest part of the horizontal sipe deeper than the deepest part of the vertical sipe, traction on snow can be further improved.

  In the above invention, in the block, the deepest portion of the vertical sipe can be deeper than the deepest portion of the horizontal sipe. By making the deepest part of the vertical sipe deeper than the deepest part of the horizontal sipe as described above, it is possible to further improve the handling stability on snow.

  In the above invention, there are one or more blocks each having a sipe on the tire center side and the tire shoulder side, and in the tire center side block, the deepest part of the horizontal sipe is deeper than the deepest part of the vertical sipe, and in the tire shoulder side block The deepest part of the vertical sipe can be deeper than the deepest part of the horizontal sipe. In this way, the deepest part of the horizontal sipe is deeper than the deepest part of the vertical sipe on the tire center side of the block, and the deepest part of the vertical sipe is deeper than the deepest part of the horizontal sipe on the tire shoulder side of the block. Thus, it is possible to improve the snow traction and the snow handling stability in a well-balanced manner.

  According to the present invention, it is possible to provide a pneumatic tire capable of optimizing the sipe shape, ensuring vertical and horizontal edge components and block rigidity, and improving not only snow acceleration and braking performance but also snow handling stability. it can.

  Next, pneumatic tires according to first and second embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a view showing a cross section of a pneumatic tire according to the first and second embodiments of the present invention by a plane including a tire rotation axis. In FIG. 1, a pneumatic tire 10 includes a pair of bead portions 1 and a pair of sidewall portions 2, and a tread portion 3 continuous in a toroid shape between the sidewall portions 2. The carcass 5 is a toroidal radial carcass that reinforces the bead portion 1, the sidewall portion 2, and the tread portion 3 between a pair of bead cores 4 embedded in the bead portion 1. The belt layer 6 of the layer or more is arranged, and the tread portion 3 is reinforced.

(First embodiment)
As shown in FIG. 2, the pneumatic tire 10 according to the first embodiment has a rib groove 14 extending along the tire circumferential direction (arrow A direction) on the tread 12 and the tire width direction (arrow B direction). It has a plurality of blocks 18 defined by extended lug grooves 16. Each block 18 has a sipe shape as shown in FIG. 2, and the horizontal sipe 22 is arranged substantially parallel to the lug groove 16, the vertical sipe 20 is arranged substantially parallel to the rib groove 14, and the horizontal sipe 22 is a block. 18 is a single-side open sipe that opens alternately only in one of the rib grooves 14 on both sides, and the vertical sipe 20 is a single-side open sipe that opens alternately only in one of the lug grooves 16 on both sides of the block 18. It has become. By making the horizontal sipe 22 a one-side open sipe, block rigidity can be secured with respect to front and rear inputs during acceleration and braking on snow, and by making the vertical sipe 20 a one-side open sipe, lateral input corresponding to snow handling stability is achieved. In contrast, block rigidity can be secured. Further, since the vertical and horizontal sipes intersect each other, the small block 18A surrounded by the sipes can be freely deformed near the block center, so that the edge effect can be exhibited regardless of the input direction. Moreover, since a block peripheral part is the large block 18B larger than a center part, block rigidity can be ensured and the excessive deformation | transformation of the whole block can be suppressed.

  In order to ensure the block rigidity, the sipe depth is also an important design parameter. In a tread pattern that emphasizes traction on snow, the sipe collapses with respect to front and rear inputs, and the deepest portion 22d of the horizontal sipe 22 is set deeper than the deepest portion 20d of the vertical sipe 20 so as to ensure traction, and the sipe is set in the circumferential direction. Is easy to open and is preferably difficult to open in the width direction.

  Also, in the tread pattern that emphasizes snow handling stability, the deepest part 20d of the vertical sipe 20 is set deeper than the deepest part 22d of the horizontal sipe 22 so that the sipe collapses with respect to the lateral input and the lateral force is secured. It is preferable that the sipe is easy to open in the lateral direction and difficult to open in the circumferential direction.

  On the other hand, assuming general usage conditions, it is necessary to improve the snow traction and snow handling stability in a well-balanced manner. For this purpose, each of the tire center side C and the tire shoulder side S has at least one block 18 having the sipe shape, and in the block 18 on the tire center side C, the deepest portion 22d of the horizontal sipe 22 is the deepest of the vertical sipe 20. It is preferable to set the sipe depth so that the deepest portion 20d of the vertical sipe 20 is deeper than the deepest portion 22d of the horizontal sipe 22 in the block 18 on the tire shoulder side S deeper than the portion 20d.

(Second Embodiment)
As shown in FIG. 3, the pneumatic tire 10 according to the second embodiment includes a rib groove 14 extending along the tire circumferential direction (arrow A direction) on the tread 12 and the tire width direction (arrow B direction). It has a plurality of blocks 18 defined by extended lug grooves 16. Each block 18 has a sipe shape as shown in FIG. 3, and the horizontal sipe 22 is arranged substantially parallel to the lug groove 16, the vertical sipe 20 is arranged substantially parallel to the rib groove 14, and the horizontal sipe 22 is a block. 18 is a double-sided open sipe that opens to the rib grooves 14 on both sides, and the vertical sipe 20 is a single-side open sipe that opens alternately to only one of the lug grooves 16 on both sides of the block 18. That is, the horizontal sipe 22 of the pneumatic tire according to the first embodiment is a single-side open sipe, whereas the horizontal sipe 22 of the pneumatic tire according to the second embodiment is a double-side open sipe. . Thus, by making the horizontal sipe 22 into a sipe that is open on both sides, the edge effect is enhanced and the acceleration and braking performance on snow is improved.

  Furthermore, by crossing the vertical and horizontal sipes, compared to the first embodiment, there are many small blocks 18A surrounded by sipes near the center of the block and can be freely deformed. An edge effect can be exhibited. Moreover, since a block peripheral part is the large block 18B larger than a center part, block rigidity can be ensured and the excessive deformation | transformation of the whole block can be suppressed.

  Moreover, since the sipe depth of the pneumatic tire according to the second embodiment is the same as the sipe depth of the pneumatic tire according to the first embodiment, the description thereof is omitted here.

(Operation and effect of the pneumatic tire according to the embodiment)
The conventional winter tire has a sipe angle that is substantially parallel to the lug groove (see, for example, the above-mentioned Japanese Patent Application Laid-Open No. 2003-104012) or an arbitrary angle (for example, the above-mentioned Japanese Patent Application Laid-Open No. 2001-191739, JP-A-8-169212 and JP-A-8-230417), designed to improve on-snow acceleration / braking performance, but to ensure on-snow handling stability, the sipe angle must be tilted. In other words, the acceleration and braking performance on the snow had to be sacrificed for the stability on the snow. The sipe shape may be, for example, a double-sided open sipe (see, for example, the above-mentioned JP-A-2001-191739, JP-A-8-169212, or JP-A-8-230417), or a double-sided sipe Therefore, it is difficult to satisfy both the edge effect and the block rigidity.

  In this embodiment, in addition to arranging a plurality of horizontal sipes that are substantially parallel to the lug grooves, a plurality of vertical sipes that intersect the horizontal sipes and that are substantially parallel to the rib grooves are arranged, and the vertical sipes are opened on one side. Siping increases the block rigidity against lateral input, ensuring snow acceleration and braking performance and snow handling stability. In addition to the vertical sipe, the horizontal sipe is a single-sided open sipe, which increases the block rigidity for the front and rear and the side.

As shown in FIG. 4, the generation mechanism of snow traction and brake is as follows: compression resistance F _{A which} is the running resistance of the entire tire surface, surface friction force F _C on the block surface, snow column shear force F _{B on the} groove, sipe edge and block edge of it can be classified into edge effect _{F D.} The object of the present invention is to increase the edge effect due to the sipe edge. The increase in the longitudinal force can be ensured by a lateral sipe, and the increase in the lateral force can be ensured by a longitudinal sipe.

The pneumatic radial tire having the sipe shape described above exhibits the effects described below. First when the snow tire travels, that snow penetrates the block edge Saipuejji portion of the tread pattern of the tire as shown in FIG. 4, the snow surface is dug up, the edge effect F _D is exhibited. Edge effect F _D is often sipe which is orthogonal to the input direction, and by the Saipuejji portion is deeper sipe depth while ensuring the block rigidity to the proper falling deformation (sipes for penetrating the open snow) growing.

  Comparing the first embodiment and the second embodiment, i.e., comparing the side sipe with one side open sipe and the one with both side open sipe, the one with the one side open sipe has higher block rigidity, Improves snow handling stability. On the other hand, a sipe that is open on both sides has a higher edge effect and improves acceleration and braking on snow.

  In addition, since the block on the tire center side is important for snow acceleration and braking, and the block on the tire shoulder side is important for snow handling stability, in this embodiment, the blocks having the sipes are the tire center side and the tire shoulder side. There are at least one each.

  In the case of a tire that places importance on snow traction, the edge effect on the front-rear input can be enhanced by making the deepest part of the horizontal sipe of the block deeper than the deepest part of the vertical sipe. Further, in the case of a tire that emphasizes on-snow handling stability, the edge effect on the lateral input can be enhanced by making the deepest part of the vertical sipe of the block deeper than the deepest part of the horizontal sipe.

  Further, in the tire center side block, the deepest part of the horizontal sipe is deeper than the deepest part of the vertical sipe, and in the tire shoulder side block, the deepest part of the vertical sipe is deeper than the deepest part of the horizontal sipe. The block on the tire center side, which is important at the time of input, can improve acceleration and braking performance on snow, and the block on the side of the tire shoulder, which is important at the time of lateral input, can improve stability on snow handling.

  The present invention will be described in detail below based on examples. In order to confirm the effect of the present invention, five types of tires of Examples 1 to 5 to which the present invention is applied and one type of tire of a comparative example are prepared, and on the snow acceleration, snow braking, and snow Comparison of handling stability was performed. The tire rim and internal pressure are based on an applicable rim and air pressure-load capacity correspondence table corresponding to the size of the radial ply tire defined in JATMA YEAR BOOK (1992, Japan Automobile Tire Association Standard).

  The tire sizes of the tires prototyped as Examples 1 to 5 are 195 / 65R15. The tread patterns and block shapes of Examples 1 to 4 were set to the shapes shown in FIG. 2 described in the first embodiment. The tread pattern and block shape of Example 5 were set to the shapes shown in FIG. 3 described in the second embodiment. The groove depth of the rib grooves and lug grooves for partitioning the blocks was 9 mm. The sipe provided in the block was horizontal sipe + vertical sipe, and as shown in Table 1 below, the vertical and horizontal sipe depths of Examples 1 to 5 were set to 4.0 mm or 7.5 mm.

  On the other hand, the tire size of the tire of the comparative example and the groove depths of the rib grooves and lug grooves were the same as in the example, but the block shape was set to the shape shown in FIG. As shown in FIG. 5, the sipe 122 provided in the block 118 of the tire of the comparative example was only a horizontal sipe without a vertical sipe, and the sipe depth was 7.5 mm.

  The negative rate was 35% in all of Examples 1 to 5 and the comparative example.

  In the test, the above tire was assembled to a 6J-15 rim at an internal pressure of 200 kPa, and mounted on a passenger car, and a snow road start / brake test was conducted. The start test to evaluate acceleration on snow was evaluated by the time (acceleration time) from the stationary state until the accelerator was fully opened and traveling 50m. The braking test to evaluate the braking performance on snow was evaluated by the braking distance when full brake was applied from 30km / h. The test of snow driving stability was evaluated by a test driver.

(result)
The results of the above test are shown in FIG. The result is expressed as an index of acceleration time, braking distance, and feeling score.

  When Examples 1-5 are compared with the comparative example, it can be seen that Examples 1-5 are all improved in terms of on-snow acceleration, on-snow braking, and on-snow handling stability. Therefore, a horizontal sipe that is substantially parallel to the lug groove and opens to at least one rib groove on both sides, and a vertical sipe that is substantially parallel to the rib groove and opens only to one of the lug grooves on both sides are provided. It can be seen that the tire according to the present embodiment improves the performance on snow.

  Moreover, when Example 4 is compared with Examples 1-3, it turns out that all of Examples 1-3 are improving on snow acceleration, snow braking, and snow handling stability. For this reason, it can be seen that the tire according to this embodiment in which the deepest portion of the horizontal sipe and the deepest portion of the vertical sipe have different depths further improve the performance on snow.

  Further, comparing Example 1 and Example 2, it can be seen that the acceleration on snow and the braking performance on snow are improved in Example 1, and the steering stability on snow is improved in Example 2. Therefore, a pneumatic tire in which the deepest part of the horizontal sipe is deeper than the deepest part of the vertical sipe improves on-snow traction, and the tire according to this embodiment in which the deepest part of the vertical sipe is deeper than the deepest part of the horizontal sipe, It can be seen that the handling stability on snow is improved.

  Moreover, when Example 3 and Examples 1-2 are compared, it turns out that Example 3 has improved on-snow acceleration, on-snow braking property, and on-snow handling stability with a good balance. Therefore, in the present embodiment, the deepest part of the horizontal sipe is deeper than the deepest part of the vertical sipe in the tire center side block, and the deepest part of the vertical sipe is deeper than the deepest part of the horizontal sipe in the tire shoulder side block. It can be seen that such a tire improves snow traction and snow handling stability in a well-balanced manner.

  Further, when Example 5 is compared with Example 1, it can be seen that the acceleration on snow and the braking performance on snow are improved in Example 5 and the steering stability on snow is improved in Example 1. Therefore, the tire according to the first embodiment in which the lateral sipe is a one-side open sipe has high block rigidity, improves snow handling stability, and the tire according to the second embodiment in which the lateral sipe is a both-side open sipe. It can be seen that the edge effect is high and the traction on snow is improved.

  As described above, it can be seen that the tire according to the present embodiment improves the performance on snow due to its sipe shape.

1 is a cross-sectional view of a pneumatic radial tire according to an embodiment of the present invention. It is a top view of the tread of the pneumatic tire concerning a 1st embodiment of the present invention. It is a top view of the tread of the pneumatic tire concerning a 2nd embodiment of the present invention. It is explanatory drawing which shows the generation | occurrence | production mechanism of a snow traction brake. It is a top view of the tread in the conventional pneumatic tire. It is explanatory drawing which shows the test result in the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Bead part 2 ... Side wall part 3 ... Tread part 4 ... Bead core 5 ... Carcass 6 ... Belt layer 10, 110 ... Pneumatic tire 12, 112 ... Tread 14, 114 ... Rib groove 16, 116 ... Lug groove 18, 118 ... Block 18A ... Small block 18B ... Large block 20 ... Vertical sipe 20d ... Vertical sipe deepest part (vertical sipe depth)
22, 122 ... Horizontal sipe 22d ... Horizontal sipe deepest part (horizontal sipe depth)
A ... Tire circumferential direction B ... Tire width direction C ... Tire center side S ... Tire shoulder side

Claims (4)

A pneumatic tire having a plurality of blocks partitioned by rib grooves extending in the tire circumferential direction and lug grooves extending in the tire width direction on the tread,
Having a plurality of sipes in the block;
The sipe is a horizontal sipe substantially parallel to the lug groove provided for each block, and a vertical sipe substantially parallel to the rib groove,
The horizontal sipe opens in at least one rib groove on both sides of the block,
The vertical sipe opens only in one of the lug grooves on both sides of the block ,
Having one or more blocks each having the sipes on the tire center side and the tire shoulder side,
In the block on the tire center side, the deepest part of the horizontal sipe is deeper than the deepest part of the vertical sipe, and in the block on the tire shoulder side, the deepest part of the vertical sipe is deeper than the deepest part of the horizontal sipe. Pneumatic tire characterized by.   The pneumatic tire according to claim 1, wherein the lateral sipe is opened only in one of the rib grooves.   The pneumatic tire according to claim 2, wherein the plurality of horizontal sipes are alternately opened in rib grooves on both sides of the block, and the plurality of vertical sipes are alternately opened in lug grooves on both sides of the block.   The pneumatic tire according to any one of claims 1 to 3, wherein a horizontal sipe and a vertical sipe intersect each other in the block, and a small block surrounded by the sipe is formed at a central portion of the block.

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