JP4048058B2 - Pneumatic tire - Google Patents

Description

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、従来例の空気入りタイヤに対し、全ての性能が大幅に向上していることが分かる。
【０１３９】
【発明の効果】
以上説明したように請求項１に記載の空気入りタイヤは上記の構成としたので、雪上において、コーナリングのみならず、トラクション、ブレーキ等の殆どの走行モードに対して性能向上を図ることができる、という優れた効果を有する。また、雪上コーナリング性能と、雪上での轍乗り越え性とを両立することができる、という優れた効果を有する。
【０１４０】
請求項２に記載の空気入りタイヤは上記の構成としたので、有効に雪上コーナリング性能を発揮できる、という優れた効果を有する。
【０１４１】
請求項３に記載の空気入りタイヤは上記の構成としたので、補助陸部を有効に働かせることができる、という優れた効果を有する。
【０１４２】
請求項４に記載の空気入りタイヤは上記の構成としたので、雪上性能を向上することができる、という優れた効果を有する。
【０１４３】
請求項５に記載の空気入りタイヤは上記の構成としたので、多量の雪を掴むことが可能となり、かつ掴んだ雪をすばやく放すことができる、という優れた効果を有する。
【０１４４】
請求項６に記載の空気入りタイヤは上記の構成としたので、雪上コーナリング性能、及びハイドロプレーニング性能を向上することができる、という優れた効果を有する。
【０１４５】
請求項７に記載の空気入りタイヤは上記の構成としたので、雪上コーナリング性能、及びハイドロプレーニング性能を確実に向上することができる、という優れた効果を有する。
【０１４６】
請求項８に記載の空気入りタイヤは上記の構成としたので、操縦性能、及び偏摩耗性能に影響を及ぼすことなく、ラウンドショルダー部及びスクエアーショルダー部の効果を出すことができる、という優れた効果を有する。
【０１４７】
請求項９に記載の空気入りタイヤは上記の構成としたので、補助陸部の効果を確実に発揮させることができる、という優れた効果を有する。
【０１４８】
請求項１０に記載の空気入りタイヤは上記の構成としたので、ショルダーブロックの剛性を確保しつつ、補助陸部を雪上で有効に働かせることができる、という優れた効果を有する。
【図面の簡単な説明】
【図１】 本発明の一実施形態に係る空気入りタイヤのトレッドの平面図である。
【図２】 本発明の一実施形態に係る空気入りタイヤのトレッドの部分拡大図である。
【図３】 本発明の一実施形態に係る空気入りタイヤのショルダー部の斜視図である。
【図４】 本発明の一実施形態に係る空気入りタイヤのショルダー部の断面図である。
【図５】 従来例の空気入りタイヤのショルダー部の斜視図ある。
【符号の説明】
１０ 空気入りタイヤ
ＣＬ タイヤ赤道面
１２ トレッド
１２Ｃ トレッド中央領域
１２Ｅ 接地端
１４ 第１の周方向主溝
１６ 第２の周方向主溝
１８ 横断主溝
２０ ショルダーブロック
２２ センターリブ
２４ 副溝
３２ サイプ
３６ サイプ
３８ サイプ
４０ サイプ
５０ 補助陸部
５２ スクエアーショルダー部
５４ ラウンドショルダー部
５６ 周方向補助溝[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a pneumatic tire, and more particularly to a winter pneumatic tire capable of improving performance on snow.
[0002]
[Prior art]
  As shown in FIG. 5, the shoulder shape that is conventionally known for winter pneumatic tires that run on the snow is provided with a bore (first recess 104 and second recess 106) on the shoulder side wall of the shoulder block 20. Most of them are formed.
[0003]
[Problems to be solved by the invention]
  In the conventional product, the shoulder block 20 was caught during cornering and caught during cornering to prevent skidding, but it hardly functioned during traction braking.
[0004]
  In consideration of the above-described facts, the present invention has an object to provide a pneumatic tire having a shoulder shape that functions effectively not only for cornering but also for most driving modes such as traction and braking on snow. .
[0005]
[Means for Solving the Problems]
  The invention according to claim 1 is a pneumatic tire comprising a tread having a plurality of blocks defined by a circumferential main groove extending in the tire circumferential direction and a transverse main groove crossing the circumferential main groove,The shoulder block has a square shoulder portion having a corner portion that is not substantially chamfered, and a round shoulder portion whose shape when viewed in a cross section along the tire rotation axis is a substantially circular curved surface,On the shoulder side wallThe square shoulder portion and the round shoulder portion are continuous on the inner side in the tire radial direction.A plurality of auxiliary land portions that form a staircase shape when viewed in a cross section along the tire rotation axis, and the outer surface portion in the tire radial direction of the auxiliary land portions is formed with irregularities in the tire circumferential direction. The block is characterized in that a plurality of zigzag sipes that are substantially parallel to the transverse main groove are formed in the block.
[0006]
  Next, the operation of the pneumatic tire according to claim 1 will be described.
[0007]
  By providing a plurality of blocks partitioned by a plurality of main grooves intersecting each other in the tread and applying sipes to these blocks, a pattern basically required for running on ice and snow is obtained.
[0008]
Here, since the square shoulder acts as a hook during cornering when running on snow, it is effective as a means of improving the cornering performance on snow. Getting worse.
[0009]
On the other hand, the round shoulder portion is difficult to get caught during snow cornering, and the snow cornering performance is deteriorated only with the round shoulder portion, but the saddle riding performance is improved.
[0010]
In the pneumatic tire of claim 1, since the shoulder block has both the square shoulder portion and the round shoulder portion, both the cornering property on snow and the ability to get over the saddle on the snow can be achieved.
[0011]
  Also,By arranging a plurality of auxiliary land portions that form a staircase shape when viewed in a cross section along the tire rotation axis on the shoulder side wall of the shoulder block, the shoulder block mainly assists when it enters the snow. Land edges function in the same way as regular block edges.
[0012]
  And since the auxiliary land part which has such an edge is extended in the tire peripheral direction, it becomes effective at the time of cornering on snow.
[0013]
  Further, by making the outer surface portion of the auxiliary land portion in the tire radial direction uneven in the tire circumferential direction, the surface area in the stepped portion increases, the contact area between snow and the shoulder block in the snow increases, and Increases traction and braking edges (uneven edges). For this reason, brake performance and traction performance are improved.
[0014]
  Here, in the present invention, the tire radial direction outer surface portion of the auxiliary land portion refers to a surface substantially parallel to the tread surface in the surface of the auxiliary land portion.
[0015]
  The invention according to claim 2 is the pneumatic tire according to claim 1, wherein the auxiliary land portion is formed in three stages in the tire radial direction, and the tire radial direction outer surface portion of the auxiliary land portion is: The tire has a zigzag shape formed from a plurality of substantially linear pieces inclined in opposite directions in a side view of the tire, and the zigzag shape has an amplitude in the range of 1 to 10 mm and a wavelength of 1 to 1. It is characterized by being within a range of 20 mm.
[0016]
  Next, the operation of the pneumatic tire according to claim 2 will be described.
[0017]
  By forming multiple auxiliary land sections in the tire radial direction, it is possible to improve the cornering performance by increasing the scratch performance in the snow, but to maximize the above-mentioned scratch performance, the shoulder that goes into the snow Within the limited width (in the tire radial direction) of the shoulder side wall of the block, it is preferable to form three auxiliary land portions in the tire radial direction.
[0018]
  Note that if the auxiliary land portion is formed in four or more steps in the tire radial direction within the limited width of the shoulder side wall, the zigzag amplitude must be reduced, and improvement in scratching performance in snow cannot be expected.
[0019]
  If the amplitude of the zigzag shape is less than 1 mm, the catch in snow is reduced, and if it exceeds 10 mm, it is difficult to arrange a plurality of auxiliary land portions in the shoulder block.
[0020]
  Furthermore, the wavelength of the zigzag shape is less than 1 mm. The effect at the time of running on snow decreases, and when it exceeds 20 mm, the edge component of the zigzag portion of the entire circumference is reduced, so that it is not possible to expect improvement in traction performance and braking performance on snow.
[0021]
  According to a third aspect of the present invention, the auxiliary land portion on the outermost side in the tire radial direction is at least an intersection of the virtual extension line of the bottom of the transverse main groove extending in the tire width direction in the tread central region and the shoulder side wall. Is also formed on the outer side in the tire radial direction.
[0022]
  Next, the operation of the pneumatic tire according to claim 3 will be described.
[0023]
  If the position where the auxiliary land portion is formed is too low (too inside in the tire radial direction), the auxiliary land portion will not work effectively when traveling on snow.
[0024]
  In order to make the auxiliary land portion work effectively, the tire diameter is more than the intersection of the virtual extension line at the bottom of the transverse main groove extending in the tire width direction in the tread central region and the shoulder side wall at least the auxiliary land portion in the tire radial direction. It is preferable to form the outer side in the direction.
[0025]
  Claim4The invention described inAny one of Claims 1-3The pneumatic tire according to claim 1, wherein the round shoulder portion is provided at a middle portion in the tire circumferential direction of the shoulder side wall of the shoulder block.
[0026]
  Next, the claim4The operation of the pneumatic tire described in 1 will be described.
[0027]
  When the round shoulder portion is provided in the middle portion of the shoulder side wall in the tire circumferential direction, at least one of the portions adjacent to the main groove opening in the shoulder portion becomes a square shoulder portion, and the width of the main groove opening in the shoulder portion is widened. The same effect is obtained, leading to improved performance on snow.
[0028]
  Claim5The invention described inAny one of Claims 1-4In the pneumatic tire according to claim 1, the round shoulder portion is arranged to be biased to one side in the tire circumferential direction of the shoulder block, protrudes outward in the tire width direction from the square shoulder portion, and has a width in the tire circumferential direction. Is characterized by becoming wider toward the inside in the tire radial direction.
[0029]
  Next, the claim5The operation of the pneumatic tire described in 1 will be described.
[0030]
  If the round shoulder portion is arranged on one side in the tire circumferential direction on the shoulder side wall of the shoulder block, it is possible to improve the snow separation performance of the snow gripped by the step between the round shoulder portion and the square shoulder portion.
[0031]
  In addition, since the width of the round shoulder portion in the tire circumferential direction becomes wider toward the inner side in the tire radial direction, the square shoulder portion adjacent to the round shoulder portion becomes wider toward the outer side in the tire radial direction, and a large amount of snow. Can be grasped at this portion, and the grabbed snow can be quickly released.
[0032]
  Claim6The invention described in claim1~ Claim5In the pneumatic tire according to any one of the above, at least one circumferential auxiliary groove substantially parallel to the tire circumferential direction is provided on a shoulder side wall between the ground contact end of the round shoulder portion and the auxiliary land portion. It is characterized by providing more than this.
[0033]
  Next, the claim6The operation of the pneumatic tire described in 1 will be described.
[0034]
  If a circumferential auxiliary groove that is substantially parallel to the tire circumferential direction is provided on the shoulder side wall between the ground contact edge of the round shoulder portion and the auxiliary land portion, this circumferential auxiliary groove also becomes a catch during snow cornering, and snow cornering Performance can be improved.
[0035]
  In addition, when running on a wet road surface, when the water depth is deep, the circumferential auxiliary groove functions as a water channel, so that the hydroplaning performance is also improved.
[0036]
  Claim7The invention described inClaim 6In the pneumatic tire according to claim 1, the circumferential auxiliary groove has a width in a range of 1 to 3 mm and a depth in a range of 0.5 to 3 mm.
[0037]
  Next, the claim7The operation of the pneumatic tire described in 1 will be described.
[0038]
  If the width of the circumferential auxiliary groove is less than 1 mm and the depth is less than 0.5 mm, the effect described in claim 7 may not be sufficiently obtained.
[0039]
  On the other hand, if the width of the circumferential auxiliary groove exceeds 3 mm and the depth exceeds 3 mm, the rigidity of the shoulder block may be reduced, and the handling performance and dry wear performance during drying may be deteriorated.
[0040]
  Claim8The invention described in claim1~ Claim7In the pneumatic tire according to any one of the above, in the round shoulder portion and the square shoulder portion excluding the auxiliary land portion, the square measured along a normal direction standing on the surface of the square shoulder portion The step size at the maximum step portion between the shoulder portion and the round shoulder portion is in the range of 1 to 5 mm.
[0041]
  Next, the claim8The operation of the pneumatic tire described in 1 will be described.
[0042]
  When the step size is less than 1 mm, the effects of the round shoulder portion and the square shoulder portion are hardly obtained.
[0043]
  On the other hand, if the step size exceeds 5 mm, the volume of the block in the round shoulder portion is reduced, and there is concern about the steering performance and uneven wear performance.
[0044]
  Claim9The invention described in claim 1 to claim 18In the pneumatic tire according to any one of the above, the distance between the auxiliary land portions measured in the radial direction of the tire is in the range of 1 to 15 mm.
[0045]
  Next, the claim9The operation of the pneumatic tire described in 1 will be described.
[0046]
  When the distance between the auxiliary land portions measured in the radial direction of the tire is less than 1 mm, it becomes difficult to function as a lateral catch component.
[0047]
  on the other hand,When the distance between the auxiliary land portions measured in the tire radial direction exceeds 15 mm, it becomes difficult to arrange the auxiliary land portions in a plurality of stages in the tire radial direction.
[0048]
  Claim10The invention described in claim 1 to claim 19In the pneumatic tire according to any one of the above, the auxiliary land portion has a thickness in a range of 0.3 to 5 mm when viewed in a cross section along the tire rotation axis.
[0049]
  Next, the claim10The operation of the pneumatic tire described in 1 will be described.
[0050]
  When the thickness of the auxiliary land portion is less than 0.3 mm, it becomes difficult to secure an edge for effectively working on snow and a surface area on the tread side.
[0051]
  On the other hand, if the thickness of the auxiliary land portion exceeds 5 mm, the amount of the shoulder side wall of the shoulder block (the amount of step difference between the surface and the bottom) becomes too large, leading to a decrease in the block rigidity of the shoulder block.
[0052]
  Claim11The invention described in 1 is a pneumatic tire having a tread having a plurality of blocks defined by a plurality of main grooves intersecting with each other, and the shoulder side wall has a staircase when viewed in a cross section along the tire rotation axis. A plurality of auxiliary land portions forming a shape, and an outer surface portion in the tire radial direction of the auxiliary land portion extends in an uneven shape in a tire circumferential direction, and the auxiliary land on the outermost side in the tire radial direction is extended. The portion is formed at the outer side in the tire radial direction from the intersection of the virtual extension line of the bottom of the main groove extending in the tire width direction in the tread central region and the shoulder side wall, and the grounding end of the round shoulder portion At least one circumferential auxiliary groove substantially parallel to the tire circumferential direction is provided on the shoulder side wall between the auxiliary land portion, and the circumferential auxiliary groove has a width of 1 to 3 mm. The depth is in the range of 0.5 to 3 mm, characterized in that.
[0053]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a plan view showing a tread 12 of a pneumatic tire 10 according to an embodiment of the present invention.
[0054]
  In FIG. 1, reference numeral 12 </ b> C denotes a tread central area that is a central area when the tread 12 is equally divided into three in the tire width direction, and reference numeral 12 </ b> S denotes a tread side area. Moreover, the code | symbol 1 / 2W of FIG.₀Indicates the tread single side contact width, arrows A and B indicate the circumferential direction, and arrow C indicates the tire width direction.
[0055]
  The definition of the tread central region 12C is as follows.
[0056]
  In the present invention, a pneumatic tire is attached to a standard rim described below, filled with standard air pressure, and applied with a standard load, one of the tread tire width direction outermost ends (ground contact end) in the tire width direction The center region when the region from the outermost end in the tire width direction to the other outermost end (contacting end) is equally divided into three is defined as the center region.
[0057]
  The standard rim is the rim specified by the Yearbook 2001 version of JATMA (Japan Automobile Tire Association), and the standard air pressure is the air pressure corresponding to the maximum load capacity of the Yearbook 2001 version of JATMA (Japan Automobile Tire Association). The load is a load corresponding to the maximum load capacity when the single wheel of Year Book 2001 version of JATMA (Japan Automobile Tire Association) is applied.
[0058]
  Outside Japan, the load is the maximum load (maximum load capacity) of a single wheel at the applicable size described in the following standards, and the air pressure is the maximum load of a single wheel (specified in the following standards). The rim is a standard rim (or “ApprovedRim” or “Recommended Rim”) in the applicable size described in the following standards.
[0059]
  The standards are determined by industry standards that are valid in the region where the tire is produced or used. For example, it is “The Tire and Rim Association Inc. Year Book” in the United States, and “The European Tire and Rim Technical Organization Standards Manual” in Europe.
[0060]
  As shown in FIG. 1, in the tread central region 12C of the tread 12, first circumferential main grooves 14 extending linearly along the tire circumferential direction are formed on both sides of the tire equatorial plane CL. Yes.
[0061]
  Further, the tread 12 is formed with a second circumferential main groove 16 extending linearly along the tire circumferential direction outside the first circumferential main groove 14 in the tire width direction.
[0062]
  The second circumferential main groove 16 of the present embodiment is formed in the vicinity of a quarter point of the tread 12.
[0063]
  The tread 12 has a transverse main groove 18 that opens to the ground contact end 12E of the tread 12 and extends from the ground contact end 12E across the second circumferential main groove 16 toward the first circumferential main groove 14. It is formed at substantially equal intervals in the direction.
[0064]
  Therefore, a plurality of shoulder blocks 20 defined by the second circumferential main groove 16 and the transverse main groove 18 are provided on the shoulder side of the tread 12, and the tire circumferential surface CL on the tire equatorial plane CL of the tread 12 is provided. A center rib 22 extending along the direction is provided.
[0065]
  The transverse main groove 18 terminates in the vicinity of the first circumferential main groove 14.
[0066]
  The transverse main groove 18 is inclined such that an angle with respect to the tire width direction gradually increases toward the tire equatorial plane CL, and the inclination directions are set to be opposite on the right side and the left side across the tire equatorial plane CL. ing.
[0067]
  A sub-groove 24 having a narrower groove width than the transverse main groove 18 is connected to the end of the transverse main groove 18 on the first circumferential main groove 14 side.
[0068]
  The groove depth of the sub-groove 24 is preferably in the range of 50 to 100% of the groove depth of the transverse main groove 18.
[0069]
  The sub-groove 24 is inclined in the same direction with respect to the tire circumferential direction from the end portion on the first circumferential main groove 14 side and extends outward in the tire width direction, and terminates in the vicinity of the adjacent transverse main groove 18. is doing.
[0070]
  The angle of the auxiliary groove 24 with respect to the tire circumferential direction is set to be relatively small.
[0071]
  As shown in FIG. 2, the angle (average value) θ formed between the sub-groove 24 and the transverse main groove 18 is preferably set to 45 ° or more.
[0072]
  Thereafter, in the present embodiment, in the land portion 26 between the first circumferential main groove 14 and the second circumferential main groove 16, a rib is provided between the first circumferential main groove 14 and the sub-groove 24. The portion between the A-shaped portion 26A, the sub-groove 24 and the second circumferential main groove 16 is referred to as a block-shaped portion 26B.
[0073]
  The average width W of the rib-like portion 26A₁Tread one side ground width 1 / 2W₀It is preferable to be within the range of 5 to 30%.
[0074]
  The end of the transverse main groove 18 on the first circumferential main groove 14 side and the first circumferential main groove 14 are connected by a narrow groove 28 having a narrower groove width than the first circumferential main groove 14. ing.
[0075]
  The narrow groove 28 has a width W₂Is preferably in the range of 0.5 to 3 mm, and the groove depth is preferably in the range of 50 to 100% of the transverse main groove 18.
[0076]
  As shown in FIG. 1, a plurality of auxiliary grooves 30 having a groove width narrower than that of the first circumferential main groove 14 are formed in the center rib 22 in the tire circumferential direction to form a block row.
[0077]
  In the present embodiment, all the auxiliary grooves 30 are inclined in the same direction.
[0078]
  The auxiliary groove 30 preferably has a width in the range of 1 to 4 mm, and preferably has a groove depth in the range of 50 to 100% of the groove depth of the first circumferential main groove 14.
[0079]
  The shoulder block 20 is formed with a plurality of zigzag sipe 32 substantially parallel to the transverse main groove 18.
[0080]
  These sipes 32 are connected to each other by a short sipe 34 at a central portion in the longitudinal direction.
[0081]
  A plurality of zigzag sipes 36 that are substantially parallel to the transverse main groove 18 are formed in the block-shaped portion 26B.
[0082]
  The rib-like portion 26A is formed with a plurality of zigzag sipe 38 having a different inclination direction from the sipe 36 of the block-like portion 26B.
[0083]
  Here, it is preferable that the amplitude of the sipe 38 formed in the rib-shaped portion 26A is set smaller than the amplitude of the sipe 36 formed in the block-shaped portion 26B.
[0084]
  The amplitude of the sipe 38 formed on the rib-like portion 26A is preferably 5 mm or less.
[0085]
  A plurality of zigzag sipes 40 that cross the center rib 22 are formed in the center rib 22 between the auxiliary groove 30 and the auxiliary groove 30.
[0086]
  The sipe 40 is inclined in the direction opposite to the auxiliary groove 30. The plurality of sipes 40 are connected to each other by a short sipe 42 at a central portion in the longitudinal direction.
[0087]
  The overall negative rate of the tread 12 is preferably in the range of 20 to 35%, and the negative rate of the tread central region 12C is preferably set smaller than the overall negative rate of the tread 12.
[0088]
  As shown in FIG. 1, the tread pattern of the pneumatic tire 10 according to the present embodiment performs groove setting as described above, and as shown in FIG. 1, it has a point-symmetric shape (a point on the tire equatorial plane CL (not shown)). ).
(Shoulder block)
  As shown in FIGS. 3 and 4, auxiliary shoulder portions 50 extending in the tire circumferential direction are formed on the shoulder side wall of the shoulder block 20 in three stages in the tire radial direction.
[0089]
  These auxiliary land portions 50 are arranged to be shifted in the tire width direction, and form a staircase shape on the shoulder side walls.
[0090]
  The tire radial direction surface portion 50A of the auxiliary land portion 50 has a zigzag shape formed from a plurality of substantially linear pieces inclined in opposite directions when viewed from the outer side in the tire width direction.
[0091]
  In the zigzag shape of the tire radial direction surface portion 50A, the amplitude 2A is preferably in the range of 1 to 10 mm, and the wavelength λ is preferably in the range of 1 to 20 mm.
[0092]
  The outermost auxiliary land portion 50 in the tire radial direction protrudes outward in the tire radial direction from the intersection of the virtual extension line FL and the shoulder side wall of the bottom of the transverse main groove 18 in the tread central region 12C.
[0093]
  The outer end portion in the tire width direction of the shoulder block 20 has a substantially square shape when viewed in a cross section along the tire rotation axis, and a square shoulder portion 52 having corner portions that are not substantially chamfered as in the present embodiment. It is preferable to have a round shoulder portion 54 having an arcuate curved surface.
[0094]
  The round shoulder portion 54 protrudes outward in the tire width direction from the square shoulder portion 52.
[0095]
  As in the present embodiment, the round shoulder portion 54 is preferably disposed in the middle portion in the tire circumferential direction of the shoulder block 20 so that the square shoulder portions 52 are provided on both sides in the tire circumferential direction, and further on one side in the tire circumferential direction. It is preferable that the shoulder block 20 and the square shoulder portion 52 on the other side in the tire circumferential direction are arranged so as to be biased toward one side in the tire circumferential direction so that the dimensions in the tire circumferential direction are different.
[0096]
  Moreover, it is preferable that the round shoulder part 54 makes the width | variety of a tire circumferential direction wide as it goes inside a tire radial direction like this embodiment.
[0097]
  It is preferable to provide at least one circumferential auxiliary groove 56 substantially parallel to the tire circumferential direction on the shoulder side wall between the ground contact end of the round shoulder portion 54 and the auxiliary land portion 50. In the present embodiment, two circumferential auxiliary grooves 56 are formed.
[0098]
  The circumferential auxiliary groove 56 has a width W_ThreeIs preferably in the range of 1 to 3 mm, and the groove depth d is preferably in the range of 0.5 to 3 mm.
[0099]
  In the round shoulder portion 54 and the square shoulder portion 52 excluding the auxiliary land portion 50, the largest step portion between the square shoulder portion 52 and the round shoulder portion 54 measured along the normal direction standing on the surface of the square shoulder portion 52. The step size S is preferably in the range of 1 to 5 mm.
[0100]
  The mutual distance P measured in the tire radial direction of the auxiliary land portion 50 is preferably within a range of 1 to 15 mm.
[0101]
  The thickness t of the auxiliary land portion 50 is preferably in the range of 0.3 to 5 mm.
[0102]
  In the pneumatic tire 10 of the present embodiment, the overall negative rate of the tread 12 is 27%, the negative rate of the tread central region 12C is 26.7%, and the first circumferential main groove 14 has a groove width of 6.5 mm. The groove depth is 10 mm, the second circumferential main groove 16 has a groove width of 5.5 mm, the groove depth is 10 mm, and the transverse main groove 18 has an end on the first circumferential main groove 16 side. 6 mm at the edge, 7.5 mm at the grounding end 12E, the groove depth is 10 mm, the angle θ between the transverse groove 18 and the auxiliary groove 24 is 57 degrees, the auxiliary groove 24 is 2.5 mm in width, and the groove depth is 7 0.5 mm, the narrow groove 28 has a width of 1.0 mm, the groove depth is 7.5 mm, the auxiliary groove 30 has a width of 2 mm, the groove depth is 7.5 mm, and the width (average) of the rib-like portion 26A is a tread. 15% of one-side ground contact width ½ W, each sipe has a width of 0.5 mm and a depth of 8 mm.
[0103]
  Further, the zigzag shape of the tire radial surface portion 50A of the auxiliary land portion 50 has an amplitude 2A of 3 mm and a wavelength λ of 5 mm, and an inter-distance P measured in the tire radial direction of the auxiliary land portion 50 is 5.5 mm. The thickness t of the land portion 50 is 1.3 mm on average, and the width W of the circumferential auxiliary groove 56_ThreeIs 1.5 mm, the groove depth d is 0.8 mm, and the step dimension S between the shoulder side wall of the round shoulder portion 54 and the shoulder side wall of the square shoulder portion 52 is 3 mm at the maximum.
(Function)
  Next, the operation and effect of the pneumatic tire 10 of the present embodiment will be described.
[0104]
  In the pneumatic tire 10 of the present embodiment, the two first circumferential main grooves 14 are disposed in the tread central region 12C, and the second circumferential main grooves 16 are disposed on both sides thereof. It can ensure drainage performance and skid performance on snow.
[0105]
  Since a plurality of transverse main grooves 18 extending in the tire width direction are arranged on the tread 12 and a plurality of shoulder blocks 20 having a plurality of sipes 32 extending in the tire width direction are arranged on the shoulder side, lug groove components in the tire width direction are arranged. And the performance on ice and snow is improved by the edge component.
[0106]
  The sub-groove 24 removes the pseudo water film on the ice when running on ice near the center of the land portion 26 in the tire width direction, and removes the water film on the road surface when running on wet roads, thus improving on-ice performance and wet performance. I can do it.
[0107]
  Since the sub-groove 24 is not connected to the adjacent transverse main groove 18, the rigidity of the land portion 26 does not become too low, and there is no adverse effect when traveling on a dry road surface.
[0108]
  Since the sub-groove 24 extends from the end of the transverse main groove 18 on the first circumferential main groove side to the outer side in the tire width direction, the lug groove component in the tire width direction increases, and the traction on ice and snow is increased. , And braking performance.
[0109]
  Since the land portion 26 has a rib-like portion 26A continuous in the tire circumferential direction, an actual contact area can be secured, which is advantageous for performance on ice. Further, since the sipe 38 having a small amplitude that is advantageous for braking performance on ice is formed in the rib-shaped portion 26A, it is further advantageous for braking performance on ice.
[0110]
  The land portion 26 between the first circumferential main groove 14 and the second circumferential main groove 16 is formed with a sipe 36 and a sipe 38 having different inclination directions, so that the vehicle is unidirectional during braking on ice. There is no fear of flowing.
[0111]
  The center rib 22 has a plurality of auxiliary grooves 30 formed in the circumferential direction of the tire to form a block row, which is advantageous for traction performance and braking performance on snow. In addition, straight running stability increases on the road surface on snow, ice, wet, and dry, and the steering wheel feels secure.
[0112]
  Since the transverse main groove 18 and the first circumferential main groove 14 are connected by the narrow groove 28, the rigidity of the rib-like portion 26A can be adjusted so that the performance on ice can be improved.
[0113]
  Since the overall negative rate of the tread 12 is in the range of 20 to 35%, the actual contact area is increased in comparison with the conventional tire, and the braking performance on ice and the traction performance on ice can be improved.
[0114]
  Since the negative rate of the tread central region 12C is set to be smaller than the overall negative rate of the tread 12, the land portion ratio in the tread central region 12C is more than the land portion ratio in the tread side region 12S on both sides thereof. It becomes effective for braking performance on ice, and also effective for suppressing uneven wear (so-called center wear) of the tire center portion.
[0115]
  The tread central region 12C is a region that has a high contribution to on-ice performance, on-snow performance, wet performance, and the like, so that the on-ice performance, on-snow performance, and wet performance can be maintained over a long period of time by suppressing wear. Become.
[0116]
  Further, since the tread pattern of the pneumatic tire 10 of the present embodiment is point-symmetric with respect to a point (not shown) on the tire equatorial plane CL, the tire mounting direction is not limited, and the tire mounting position. Replacement (so-called rotation) is facilitated, and it is effective in preventing uneven wear.
(Operation of shoulder)
  In the pneumatic tire 10 of the present embodiment, since the auxiliary land portion 50 is arranged in a plurality of stages on the shoulder side wall of the shoulder block 20, when the shoulder block 20 enters the snow, the edge of the auxiliary land portion 50 is usually It functions in the same way as the edge of the block and improves cornering performance on snow.
[0117]
  In addition, since the surface portion in the tire radial direction of the auxiliary land portion 50 is formed in a zigzag shape in the tire circumferential direction, the surface area in the stepped portion increases, the contact area between the snow and the shoulder block 20 in the snow increases, and the traction Further, since the edge effective for braking increases, the braking performance and the traction performance are improved.
[0118]
  The shoulder block 20 of the present embodiment has a square shoulder portion 52 that acts as a hook during cornering during running on snow, and a round shoulder portion 54 that is effective for overcoming saddle riding. It is possible to achieve both saddle-riding ability.
[0119]
  Since the square shoulder portions 52 are provided on both sides of the shoulder block side opening end of the transverse main groove 18, the same effect as that obtained by widening the width of the transverse main groove 18 at the shoulder portion is obtained, leading to improvement in performance on snow.
[0120]
  Since the round shoulder portion 54 is arranged so as to be biased to one side of the shoulder block 20 in the tire circumferential direction, it is possible to improve the snow separation performance of the snow gripped by the step between the round shoulder portion 54 and the square shoulder portion 52.
[0121]
  Further, since the width in the tire circumferential direction of the round shoulder portion 54 becomes wider toward the inner side in the tire radial direction, the square shoulder portion adjacent to the round shoulder portion 54 becomes wider toward the outer side in the tire radial direction. It becomes possible to grab snow at this part, and it is possible to release the grabbed snow quickly.
[0122]
  Since the circumferential auxiliary groove 56 that acts as a water channel and is caught during snow cornering, the snow cornering performance and hydroplaning performance can be improved.
[0123]
  If the auxiliary groove 30 is wide like the first circumferential main groove 14, the rigidity is lowered, and adverse effects such as worse feeling, uneven wear, and noise may occur.
[0124]
  Width W of rib-like portion 26A₁However, if it becomes less than 5% of the tread one-side ground contact width 1 / 2W, the rib-like portion 26A becomes too thin, and there is a possibility that the effect on ice may be lost.
[0125]
  On the other hand, the width W of the rib-like portion 26A₁However, if it exceeds 30% of the tread one-side ground contact width ½ W, the transverse main groove 18 becomes short, and it becomes difficult to ensure performance on snow.
[0126]
  If the angle θ formed between the transverse main groove 18 and the sub-groove 24 is less than 45 °, the corner of the block-shaped portion 26B becomes too acute, and there is a concern that uneven wear may occur.
[0127]
  As for the zigzag shape of the auxiliary land portion 50, when the amplitude 2A is less than 1 mm, the catch in the snow is reduced, and when it exceeds 10 mm, it is difficult to arrange the auxiliary land portion 50 in the shoulder block 20 in a plurality of stages.
[0128]
  The zigzag shape of the auxiliary land portion 50 has a wavelength λ of less than 1 mm. The effect at the time of running on snow decreases, and when it exceeds 20 mm, the edge component of the zigzag portion of the entire circumference is reduced, so that it is not possible to expect improvement in traction performance and braking performance on snow.
[0129]
  Width W of circumferential auxiliary groove 56_ThreeWhen the depth d is less than 1 mm and the depth d is less than 0.5 mm, the cornering performance on snow and the hydroplaning performance cannot be improved. On the other hand, the width W_ThreeWhen the thickness exceeds 3 mm and the depth d exceeds 3 mm, the rigidity of the shoulder block 20 is reduced, and there is a concern that the handling performance during dryness and the uneven wear performance may be deteriorated.
[0130]
  When the step dimension S between the shoulder side wall of the round shoulder portion 54 and the shoulder side wall of the square shoulder portion 52 is less than 1 mm, the effects of the round shoulder portion 54 and the square shoulder portion 52 are hardly obtained. On the other hand, when the step size S exceeds 5 mm, the volume of the round shoulder portion 56 is reduced, and there is concern about the steering performance and the uneven wear performance.
[0131]
  When the distance P between the auxiliary land portions 50 measured in the tire radial direction is less than 1 mm, the auxiliary land portion 50 hardly functions as a lateral catch component. On the other hand, when the distance P between the auxiliary land portions 50 measured in the tire radial direction exceeds 15 mm, it is difficult to arrange the auxiliary land portions 50 in a plurality of stages in the tire radial direction.
[0132]
  When the thickness t of the auxiliary land portion 50 is less than 0.3 mm, it is difficult to secure an edge for effectively working on snow and a surface area on the tread side. On the other hand, if the thickness t exceeds 5 mm, the rigidity of the shoulder block 20 is reduced.
(Test example)
  In order to confirm the effect of the present invention, a conventional pneumatic tire and a pneumatic tire according to an embodiment to which the present invention is applied are prepared, snow feeling performance, snow braking performance, snow traction performance, and wet hydroplaning. A performance comparison was made.
[0133]
  Example pneumatic tire: The pneumatic tire described in the above embodiment.
[0134]
  Conventional pneumatic tire: It has a tread pattern similar to that of the pneumatic tire of the example, but only the shape of the shoulder portion is different as shown in FIG.
[0135]
  In the pneumatic tire 100 of the conventional example, the shoulder portions of the shoulder block 20 are all round shoulder portions 102, and the first recess 104 is formed on the shoulder side wall at a position away from the tread at the opening portion of the transverse groove 18. A second recess 106 that opens to the tread surface side is formed in the circumferential center portion of the shoulder block 20.
[0136]
  The tire size is PSR205 / 65R15 for all tires.
[0137]
  The test method and evaluation will be briefly described below.
-Feeling performance on snow: Comprehensive evaluation of braking performance, starting performance, straight travel performance, and cornering performance (by test driver) on a test course on a snowy road surface. The evaluation is represented by an index with the conventional feeling as 100, and the larger the value, the better the feeling on snow.
・ Brake performance on snow: Measures braking distance when full braking is performed from 40km / h on snow. The evaluation is represented by an index in which the reciprocal of the braking distance of the conventional example is 100, and the larger the value, the better the snow braking performance.
-Snow traction performance: Measures acceleration time from start at a distance of 50m above snow. The evaluation is represented by an index with the reciprocal of the acceleration time of the conventional example as 100, and the larger the value, the better the traction performance on snow.
-Wet hydroplaning performance: Feeling evaluation of the critical speed of hydroplaning when passing through a wet road surface with a water depth of 10 mm.
[0138]
[Table 1]

  From the test results, it can be seen that the pneumatic tires of the examples to which the present invention is applied are greatly improved in all performances compared to the conventional pneumatic tires.
[0139]
【The invention's effect】
  As described above, since the pneumatic tire according to claim 1 has the above-described configuration, on snow, not only cornering, but also performance improvement can be achieved for most driving modes such as traction and brake. It has an excellent effect.Moreover, it has the outstanding effect that the cornering performance on snow and the saddle-riding property on snow can be made compatible.
[0140]
  Since the pneumatic tire according to claim 2 has the above-described configuration, it has an excellent effect that cornering performance on snow can be effectively exhibited.
[0141]
  Since the pneumatic tire according to claim 3 has the above-described configuration, it has an excellent effect that the auxiliary land portion can work effectively.
[0142]
  Claim4Since the pneumatic tire described in 1 is configured as described above, it has an excellent effect that the performance on snow can be improved.
[0143]
  Claim5Since the pneumatic tire described in 1 is configured as described above, it has an excellent effect that a large amount of snow can be grasped and the grabbed snow can be quickly released.
[0144]
  Claim6Since the pneumatic tire described in 1 is configured as described above, it has an excellent effect that the cornering performance on snow and the hydroplaning performance can be improved.
[0145]
  Claim7Since the pneumatic tire described in 1 has the above-described configuration, it has an excellent effect that the cornering performance on snow and the hydroplaning performance can be surely improved.
[0146]
  Claim8Since the pneumatic tire described in 1 is configured as described above, it has an excellent effect that the effects of the round shoulder portion and the square shoulder portion can be obtained without affecting the steering performance and the uneven wear performance.
[0147]
  Claim9Since the pneumatic tire described in (1) has the above-described configuration, it has an excellent effect that the effect of the auxiliary land portion can be surely exhibited.
[0148]
  Claim10Since the pneumatic tire described in (1) has the above-described configuration, it has an excellent effect that the auxiliary land portion can be effectively operated on snow while ensuring the rigidity of the shoulder block.
[Brief description of the drawings]
FIG. 1 is a plan view of a tread of a pneumatic tire according to an embodiment of the present invention.
FIG. 2 is a partially enlarged view of a tread of a pneumatic tire according to an embodiment of the present invention.
FIG. 3 is a perspective view of a shoulder portion of a pneumatic tire according to an embodiment of the present invention.
FIG. 4 is a cross-sectional view of a shoulder portion of a pneumatic tire according to an embodiment of the present invention.
FIG. 5 is a perspective view of a shoulder portion of a conventional pneumatic tire.
[Explanation of symbols]
        10 Pneumatic tire
        CL tire equator
        12 tread
        12C tread central area
        12E Grounding end
        14 First circumferential main groove
        16 Second circumferential main groove
        18 Transverse main groove
        20 Shoulder block
        22 Center rib
        24 minor groove
        32 Sipe
        36 Sipe
        38 Sipe
        40 Sipe
        50 Auxiliary land
        52 Square shoulder
        54 Round shoulder
        56 Circumferential auxiliary groove

Claims (11)

A pneumatic tire comprising a tread having a plurality of blocks defined by a circumferential main groove extending in a tire circumferential direction and a transverse main groove crossing the circumferential main groove,
The shoulder block has a square shoulder portion having a corner portion that is not substantially chamfered, and a round shoulder portion whose shape when viewed in a cross section along the tire rotation axis is a substantially circular curved surface,
The shoulder side wall has a plurality of auxiliary land portions that form a staircase shape when viewed in a cross section along the tire rotation axis while continuing to the inside in the tire radial direction of the square shoulder portion and the round shoulder portion ,
The outer surface portion of the auxiliary land portion in the radial direction of the tire extends in an uneven shape in the tire circumferential direction,
The pneumatic tire according to claim 1, wherein a plurality of zigzag sipes that are substantially parallel to the transverse main groove are formed in the block. The auxiliary land portion is formed in three stages in the tire radial direction,
The outer radial surface portion of the auxiliary land portion in the tire radial direction has a zigzag shape formed from a plurality of substantially linear pieces inclined in opposite directions in a side view of the tire,
The pneumatic tire according to claim 1, wherein the zigzag shape has an amplitude in a range of 1 to 10 mm and a wavelength in a range of 1 to 20 mm.   The auxiliary land portion on the outermost side in the tire radial direction is formed on the outer side in the tire radial direction from the intersection of the virtual extension line of the groove bottom of the transverse main groove extending in the tire width direction in the tread central region and the shoulder side wall. The pneumatic tire according to claim 1, wherein the pneumatic tire is a pneumatic tire. The pneumatic tire according to any one of claims 1 to 3, wherein the round shoulder portion is provided at a middle portion in a tire circumferential direction of the shoulder side wall of the shoulder block. The round shoulder portion is arranged so as to be biased to one side in the tire circumferential direction of the shoulder block, protrudes outward in the tire width direction from the square shoulder portion, and the width in the tire circumferential direction faces inward in the tire radial direction. Accordingly, the pneumatic tire according to any one of claims 1 to 4, which is widened. Wherein the shoulder side wall between said auxiliary land part and the ground terminal of the round shoulder portions, which are provided at least one or more substantially parallel circumferential auxiliary groove with respect to the tire circumferential direction, it is characterized by The pneumatic tire according to any one of claims 1 to 5 . The pneumatic tire according to claim 6 , wherein the circumferential auxiliary groove has a width in a range of 1 to 3 mm and a depth in a range of 0.5 to 3 mm. In the round shoulder portion and the square shoulder portion excluding the auxiliary land portion, the largest step portion between the square shoulder portion and the round shoulder portion measured along the normal direction standing on the surface of the square shoulder portion. The pneumatic tire according to any one of claims 1 to 7 , wherein a step size at is in a range of 1 to 5 mm. The pneumatic tire according to any one of claims 1 to 8 , wherein a distance between the auxiliary land portions measured in the tire radial direction is in a range of 1 to 15 mm. The thickness of the auxiliary land portion when viewed in cross-section along the tire rotational axis is in the range of 0.3 to 5 mm, it claimed in any one of claims 1 to 9, characterized in Pneumatic tires. A pneumatic tire provided with a plurality of blocks partitioned by a plurality of main grooves intersecting each other in a tread,
The shoulder side wall has a plurality of auxiliary land portions that form a step shape when viewed in a cross section along the tire rotation axis,
The outer surface portion of the auxiliary land portion in the radial direction of the tire extends in an uneven shape in the tire circumferential direction,
The auxiliary land portion on the outermost side in the tire radial direction is formed on the outer side in the tire radial direction from the intersection of the virtual extension line at the bottom of the main groove extending in the tire width direction in the tread central region and the shoulder side wall. ,
At least one circumferential auxiliary groove substantially parallel to the tire circumferential direction is provided on the shoulder side wall between the ground contact end of the round shoulder portion and the auxiliary land portion,
The circumferential auxiliary groove has a width in the range of 1 to 3 mm and a depth in the range of 0.5 to 3 mm.

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