JP4136537B2 - Pneumatic tire - Google Patents

Description

試験の結果、本発明の適用された実施例のタイヤは、従来例のタイヤに比較して、雪上フィーリング、雪上ブレーキ、雪上トラクション、氷上フィーリング、氷上ブレーキ、及び氷上トラクションの全ての項目に対して、性能が向上していることが分かる。
【０１５２】
【発明の効果】
以上説明したように本発明の空気入りタイヤによれば、氷上性能、雪上性能、及び操縦安定性を両立することができる、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】 三角ブロックの断面図である。
【図３】 従来例の空気入りタイヤのトレッドの平面図である。
【符号の説明】
１０ 空気入りタイヤ
１２ トレッド
１４ 周方向主溝
１６ 第１の横溝（横溝）
１６Ａ 幅狭部
１８ 第２の横溝（横溝）
１８Ａ 幅狭部
２０ 三角ブロック（ブロック）
２０Ａ 三角小ブロック（小ブロック）
２０Ｂ 台形小ブロック（小ブロック）
２２ 補助溝
２４ 擬似周方向リブ
２６ 面取り
２６Ａ 開始位置
２８ サイプ
３０ 第３の横溝（横溝）
ＴＷ 踏面幅
ＣＬ タイヤ赤道面[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire that achieves braking on an icy road with a low coefficient of friction, improved traction performance, and improved performance on snow.
[0002]
[Prior art]
  2. Description of the Related Art Conventionally, in a pneumatic tire, a studless tread pattern with improved performance on ice has a zigzag groove 100 and a straight groove 102 extending in the circumferential direction (arrow A direction and arrow B direction) as shown in FIG. In general, a block pattern including a block 108 with a sipe 106 partitioned by a lateral groove 104 is generally used.
[0003]
[Problems to be solved by the invention]
  A very thin pseudo water film is generated between the tire and the ice road (within the actual ground contact surface) on the icy road (with an ice temperature of around 0 ° C) with a low coefficient of friction (μ). It is slippery.
[0004]
  In order to obtain a higher braking driving force, it is effective to gain more contact area and efficiently remove the pseudo water film in order to obtain a frictional force on the ice surface.
[0005]
  In the conventional pattern of sipe engraved on the block pattern, it has been difficult to secure both the contact area and the removal of the water film formed on the block and the icy road surface when the block is grounded.
[0006]
  In addition, because of the block pattern, if more sipes are cut for water removal, the block rigidity is lowered, leading to deterioration in steering stability and the like.
[0007]
  In view of the above facts, an object of the present invention is to provide a pneumatic tire that can achieve both on-ice performance, on-snow performance, and steering stability.
[0008]
[Means for Solving the Problems]
  According to the first aspect of the present invention, the tread is disposed between the pair of circumferential main grooves by arranging a pair of circumferential main grooves extending substantially parallel to the tire circumferential direction on the tread. A land portion row and a pair of land portion rows on the outer side in the tire axial direction of the pair of circumferential main grooves, and the central land portion row and the both side land portion rows each extend in a land crossing direction. The pneumatic tire is composed of a plurality of blocks defined by transverse grooves, and the central land portion row has a plurality of triangular blocks having a substantially triangular shape that is long in the tire axial direction in a tread plan view. Are arranged opposite to each other along the tire circumferential direction so that the apex and the base opposite to the vertex are alternately arranged in the tire circumferential direction, and the triangular blocks are arranged in the tire circumferential direction. Little to extend By one of the auxiliary groove with, is divided into a plurality of small blocks in the tire axial direction, the blocks of the two side land portion row, and has a hexagonal tread plan view, is characterized in that.
[0009]
  Next, the operation of the pneumatic tire according to claim 1 will be described.
[0010]
  First, since the pair of circumferential main grooves extending substantially parallel to the tire circumferential direction are arranged on the tread, wet hydroplaning performance and skid performance on ice and snow can be ensured.
[0011]
  In addition, by arranging a pair of circumferential main grooves in the tread, three block rows are formed roughly, and the central region between the pair of circumferential main grooves is effective for performance on ice, Both side regions on both sides can be set to be effective for performance on snow.
[0012]
  A plurality of lateral grooves provided in the tread can secure a block edge component necessary for running on snow.
[0013]
  Near the apex of the triangular block, the rigidity is low and the movement at the time of grounding is large. On the other hand, the area near the bottom is high in rigidity and is difficult to fall down when grounding.
[0014]
  By arranging multiple triangular blocks in opposite directions so that the apex with the smallest angle and the base opposite to the apex are alternately arranged in the tire circumferential direction, the vicinity of the base is reliably secured Make contact with the surface to gain friction with the icy road surface, and move the block near the top to remove the pseudo water film on the road surface by the wiper effect before the bottom of the adjacent triangular block touches the ground. Thus, the vicinity of the bottom of the triangular block can be reliably grounded to the road surface, and the braking performance and traction performance on ice can be improved.
[0015]
  When the tread width becomes wider, if the tread is divided into three in the tire axial direction by a pair of circumferential main grooves, the rigidity of the central land row may be too high, so the block rigidity is effective for performance on ice and snow. For this purpose, the triangular block may be divided in the tire axial direction by the auxiliary groove.
[0016]
  Further, by providing the auxiliary groove, an edge in the lateral direction (effective for cornering) can be formed, so that cornering performance on ice and snow is improved.
  In the lateral groove that defines the hexagonal block in the tread plan view of the land sections on both sides, if the groove width is the minimum width at the center in the tire axial direction, the noise generated when the road surface is grounded rather than a constant width. It is less likely to cause uneven wear (heel and toe wear) on both side land sections.
  Furthermore, in the lateral grooves that define the hexagonal blocks in the tread plan view of the land sections on both sides, the groove width is gradually increased from the tire axial center to the tire equator side and the tread end side. , You can earn groove volume and ensure performance on snow.
  In addition, the circumferential block rigidity in the vicinity of the center in the tire axial direction of both land portions can be increased, and the falling of the block during ice braking and traction on ice can be suppressed, leading to improved performance on ice.
[0017]
  According to a second aspect of the present invention, in the pneumatic tire according to the first aspect, the auxiliary groove sandwiches the tire equator plane when one of the triangular blocks is viewed in the tire circumferential direction. In the right side, the other triangular block adjacent to the one triangular block is disposed on the left side with the tire equatorial plane in between, and between the auxiliary groove on the right side and the auxiliary groove on the left side with the tire equatorial plane in between. , The width of the lateral groove is narrower than the portion of the lateral groove between the left and right auxiliary grooves than the portion of the left and right auxiliary grooves in the region outside the tire axial direction. The narrow portion is a pseudo portion that is substantially continuous in the tire circumferential direction at the center portion in the tread width direction when the groove walls facing each other come into contact with each other when contacted with the road surface by load rolling. Form circumferential ribs So that is set with a groove width, the pseudo circumferential rib has a width that is set in a range of 5-25% of the tread width, is characterized in that.
[0018]
  Next, the operation of the pneumatic tire according to claim 2 will be described.
[0019]
  When the narrow portion of the lateral groove contacts the road surface, the opposing groove walls come into contact with each other, and a pseudo circumferential rib substantially continuous in the tire circumferential direction is formed at the center portion in the tread width direction.
[0020]
  As a result, the block rigidity in the tread central area is increased and the actual contact area is also increased, so that the brake edge and traction performance on ice can be improved, and the block edge component can be earned by completely comparing the ribs continuous in the tire circumferential direction. Therefore, braking performance on snow and traction performance are also improved.
[0021]
  Here, when the width of the pseudo circumferential rib is less than 5% of the tread width, the function as the pseudo circumferential rib is lowered, and the performance on ice is not improved so much.
[0022]
  On the other hand, if the width of the quasi-circumferential rib exceeds 25% of the tread width, the area of the quasi-circumferential rib having a low negative rate becomes too wide, and there is a concern that the performance on snow may deteriorate.
[0023]
  Therefore, the width of the pseudo circumferential rib is preferably set in a range of 5 to 25% of the tread width.
[0024]
  The tread width here means that the pneumatic tire is mounted on a standard rim prescribed by JATMA YEAR BOOK (2002 edition, Japan Automobile Tire Association Standard), and the size and ply rating applicable to JATMA YEAR BOOK. When 100% of the air pressure (maximum air pressure) corresponding to the maximum load capacity (internal pressure-load capacity correspondence table) is filled, placed in a stationary state perpendicular to the flat plate and loaded with the maximum load capacity This is the width in the tire axial direction of the contact surface.
[0025]
  In addition, when the TRA standard and the ETRTO standard are applied in the place of use or manufacturing place of the tire, the respective standards are followed.
[0026]
  According to a third aspect of the present invention, in the pneumatic tire according to the first or second aspect, the pair of circumferential main grooves are disposed substantially symmetrically with respect to the tire equatorial plane, and the interval therebetween is the tread. It is characterized by being set to 35 to 65% of the tread width.
[0027]
  Next, the operation of the pneumatic tire according to claim 3 will be described.
[0028]
  The pair of circumferential main grooves are basically arranged so that the size of the both side land portion rows does not become too small, that is, the basic rigidity can be secured.
[0029]
  When the distance between the pair of circumferential main grooves is less than 35% of the tread surface width, the area of the central land portion row becomes too small, leading to deterioration of on-ice performance.
[0030]
  On the other hand, when the distance between the pair of circumferential main grooves exceeds 65% of the tread surface width, the rigidity of the land sections on both sides becomes too small, leading to deterioration in uneven wear performance and cornering performance on ice and snow.
[0031]
  Also, if the pair of circumferential main grooves are not arranged substantially symmetrically across the tire equatorial plane, the size of one of the land sections on both sides will be too small and the size of the other will be too large, Can not be removed.
[0032]
  Therefore, it is preferable that the pair of circumferential main grooves are disposed substantially symmetrically with the tire equatorial plane interposed therebetween, and the interval is set to 35 to 65% of the tread width of the tread.
[0033]
  According to a fourth aspect of the present invention, in the pneumatic tire according to any one of the first to third aspects, the pair of circumferential main grooves has a groove width of 7 to 7 times the tread width of the tread. It is characterized by being set within a range of 20%.
[0034]
  Next, the operation of the pneumatic tire according to claim 4 will be described.
[0035]
  Basically, since the tread has only two circumferential main grooves, the circumferential main grooves are set to be thick in order to ensure wet hydroplaning performance.
[0036]
  Here, when the groove width of the circumferential main groove is less than 7% of the tread surface width, the drainage performance is lowered, and there is a concern that the wet hydroplaning performance is deteriorated.
[0037]
  On the other hand, if the groove width of the circumferential main groove exceeds 20% of the tread surface width, there is a concern about uneven wear (single drop wear) of both side land sections.
[0038]
  Therefore, it is preferable to set the groove width of the circumferential main groove within a range of 7 to 20% of the tread surface width.
[0039]
[0040]
[0041]
[0042]
[0043]
[0044]
  Claim 5The invention described inThe method according to any one of claims 1 to 4.In the pneumatic tire, a plurality of sipes extending along the longitudinal direction of the triangular block are formed in the triangular block, and the number of sipes arranged in the tire circumferential direction gradually increases from the apex toward the base. It is characterized by that.
[0045]
  next,Claim 5The operation of the pneumatic tire described in 1 will be described.
[0046]
  At the apex of the triangular block, the thickness of the block in the tire circumferential direction is thin and the rigidity is low, so the number of sipes is set to be small, but the thickness of the block in the tire circumferential direction gradually increases on the bottom side, so The number can be increased from the apex to the base.
[0047]
  By arranging a plurality of sipes in the triangular block in this way, a large number of small block can be formed, and an effective edge component on ice and snow can be obtained.
[0048]
  Claim 6The invention described inClaim 5The pneumatic tire described in 1 is characterized in that the sipe interval in the tire circumferential direction is substantially constant.
[0049]
  next,Claim 6The operation of the pneumatic tire described in 1 will be described.
[0050]
  In the triangular block, by making the sipe interval in the tire circumferential direction substantially constant, it is possible to make the rigidity uniform without creating an extremely low rigidity place.
[0051]
  Claim 7The invention described inThe method according to any one of claims 1 to 6.In the pneumatic tire, the triangular blocks are alternately arranged in the tire circumferential direction with first lateral grooves and second lateral grooves inclined at a constant angle and having a larger angle with respect to the tire axial direction than the first lateral grooves. It is characterized by being partitioned by being done.
[0052]
  next,Claim 7The operation of the pneumatic tire described in 1 will be described.
[0053]
  Since the first lateral groove has an angle with respect to the tire axial direction that is smaller than that of the second lateral groove, it is effective for traction and braking in a region close to straight traveling, and the second lateral groove has an angle with respect to the tire axial direction that is greater than that of the first lateral groove. Therefore, the traction performance and the braking performance during cornering work effectively, and therefore, the performance on ice and snow can be exhibited in all steering angle regions.
[0054]
  Claim 8The invention described inClaim 7In the pneumatic tire according to claim 1, the angle of the first lateral groove with respect to the tire axial direction is within a range of 0 to 20 ° measured from an acute angle side, and the angle of the second lateral groove with respect to the tire axial direction is 10 to 45 °. It is set within the range of.
[0055]
  next,Claim 8The operation of the pneumatic tire described in 1 will be described.
[0056]
  The angle of the first lateral groove is set within a range of 0 to 20 ° close to the tire axial direction in order to improve performance on ice and snow in a state close to straight traveling. In order to form a triangular block in combination with the first lateral groove, the angle of the second lateral groove is set within a range of 10 to 45 °.
[0057]
  If the angle of the second lateral groove exceeds 45 °, the traction performance and the brake performance are deteriorated.
[0058]
  Claim 9The invention described inClaim 7 or claim 8In the pneumatic tire of the present invention, the lateral groove that defines the hexagonal block in the tread plan view of the both-side land portion row continues from the first tread groove toward the other tread edge. The second lateral groove is formed continuously from one tread end toward the other tread end, and is formed by intersecting the first lateral groove and the second lateral groove. It is characterized by.
[0059]
  next,Claim 9The operation of the pneumatic tire described in 1 will be described.
[0060]
  The lateral grooves that divide the blocks of the both-side land portion rows can discharge a part of the water in the circumferential main grooves to the outside of the tread end.
[0061]
  By creating a transverse groove that divides the block of the land section row on both sides by intersecting the first transverse groove and the second transverse groove, water near the ground center is passed through the first transverse groove and the second transverse groove. It can be efficiently discharged to the outside of the tread end.
[0062]
  Further, when the apex of the triangular block protrudes into the circumferential main groove, the protruding portion serves as a resistance to the flow of water in the circumferential main groove. Since the horizontal grooves (the first horizontal groove and the second horizontal groove) discharge to the outside of the tread end, a decrease in drainage performance can be suppressed.
[0063]
  Claim 10The invention described inThe method according to any one of claims 1 to 9.In the pneumatic tire, the apex of the triangular block protrudes inward of the circumferential main groove from the bottom of another triangular block adjacent in the circumferential direction, and protrudes into the circumferential main groove The portion is characterized by chamfering in which the height gradually decreases toward the apex.
[0064]
  next,Claim 10The operation of the pneumatic tire described in 1 will be described.
[0065]
  By projecting the apex of the triangular block into the circumferential main groove, the block edge component can be increased in the circumferential main groove to improve the performance on snow.
[0066]
  However, since the vicinity of the apex of the triangular block is disadvantageous in terms of rigidity, chamfering is performed and the depth is gradually increased toward the apex, so that it acts as an edge when the tire penetrates into the snow.
[0067]
  Claim 11The invention described inClaim 10In the pneumatic tire according to claim 1, the start position of the chamfering is at least on the tire equator surface side from the bottom of another triangular block adjacent in the tire circumferential direction, and the triangular block is inserted into the circumferential main groove. The protrusion amount of the apex is set within a range of 30 to 70% of the groove width of the circumferential main groove.
[0068]
  next,Claim 11The operation of the pneumatic tire described in 1 will be described.
[0069]
  By arranging the chamfering start position at least on the tire equator surface side from the bottom of other triangular blocks adjacent in the tire circumferential direction, the edge enters and exits even on the ground contact surface, leading to improved performance on snow.
[0070]
  Further, considering the edge effect, the protrusion amount of the apex of the triangular block needs to be 30% or more of the groove width of the circumferential main groove.
[0071]
  Further, the amount of protrusion at the apex of the triangular block is preferably suppressed to 70% or less of the groove width of the circumferential main groove in consideration of the drainage property of the circumferential main groove, that is, the hydro-peening property.
[0072]
  Claim 12The invention described inThe method according to any one of claims 1 to 11.In the pneumatic tire, the angle of the auxiliary groove with respect to the tire circumferential direction is set in a range of 0 ° to 45 ° as measured from the acute angle side.
[0073]
  next,Claim 12The operation of the pneumatic tire described in 1 will be described.
[0074]
  When the angle of the auxiliary groove is 0 °, it acts as a catch in the lateral direction like the circumferential groove. When the angle of the auxiliary groove increases, the edge component in the front-rear direction increases, which is effective for traction performance and braking performance (especially during steering). However, if the angle exceeds 45 °, an acute angle portion is formed in the block, so 45 ° The following is preferred.
[0075]
DETAILED DESCRIPTION OF THE INVENTION
  An embodiment of the pneumatic tire of the present invention will be described with reference to FIGS. 1 and 2.
[0076]
  As shown in FIG. 1, the tread 12 of the pneumatic tire 10 (tire size: 205 / 65R15) of the present embodiment has tire circumferential directions (arrow A direction and arrow B direction) on both sides of the tire equatorial plane CL. ), The circumferential main grooves 14 extending linearly along the tire equatorial plane CL are arranged at symmetrical positions.
[0077]
  The groove width SW of the circumferential main groove 14 is preferably set within a range of 7 to 20% of the tread surface width TW. In the present embodiment, the tread 12 has a tread width TW of 167 mm, the circumferential main groove 14 has a groove width SW of 11 mm, and the circumferential main groove 14 has a groove width SW of 6.5% of the tread 12 tread width TW. Is set to
[0078]
  Further, the interval P between the pair of circumferential main grooves 14 is preferably set in a range of 35 to 65% of the tread 12 width tW. In the present embodiment, the interval P between the pair of circumferential main grooves 14 is set to 50% of the tread surface width TW.
[0079]
  In the tread 12, a space between the pair of circumferential main grooves 14 is appropriately referred to as a central land portion row, and an outer side in the tire axial direction of the pair of circumferential main grooves 14 is referred to as a both-side land portion row.
[0080]
  Further, between the pair of circumferential main grooves 14, a first lateral groove 16 continuously extending from one circumferential main groove 14 to the other circumferential main groove 14, and also from one circumferential main groove 14. A second lateral groove 18 that continuously extends to the other circumferential main groove 14, is inclined in the same direction as the first lateral groove 16, and has a larger angle with respect to the tire axial direction than the first lateral groove 16, is the tire circumferential direction. Are alternately arranged.
[0081]
  Here, the angle θ1 of the first lateral groove 16 with respect to the tire axial direction is within a range of 0 to 20 ° as measured from the acute angle side, and the angle θ2 of the second lateral groove 18 with respect to the tire axial direction is within a range of 10 to 45 °. It is preferable to set to.
[0082]
  Furthermore, it is preferable to set the angle difference between θ1 and θ2 within a range of 12 to 40 °.
[0083]
  In the present embodiment, the angle θ1 of the first lateral groove 16 with respect to the tire axial direction is set to 8 °, and the angle θ2 of the second lateral groove 18 with respect to the tire axial direction is set to 25 °.
[0084]
  Between the pair of circumferential main grooves 14, a substantially triangular shape that is partitioned by the pair of circumferential main grooves 14, the first lateral grooves 16, and the second lateral grooves 18 and that is long in the tire axial direction in plan view of the tread. A plurality of triangular blocks 20 to be presented are arranged along the tire circumferential direction.
[0085]
  In addition, the triangular block 20 is an auxiliary groove that extends in a straight line with a constant width and inclines in the opposite direction to the tire equatorial plane CL with respect to the tire circumferential direction, with respect to the first lateral groove 16 and the second lateral groove 18 described above. 22 is divided into two in the tire axial direction, a triangular small block 20A having a substantially triangular shape in a tread plan view and a trapezoidal small block 20B having a substantially trapezoidal shape.
[0086]
  The auxiliary groove 22 is formed at a position closer to the shortest bottom side of the triangle than the tire equatorial plane CL.
[0087]
  Here, the angle θ3 of the auxiliary groove 22 with respect to the tire circumferential direction is preferably set within a range of 0 ° to 45 ° as measured from the acute angle side.
[0088]
  The auxiliary groove 22 of the present embodiment has a groove width HW of 4.8 mm and an angle θ3 with respect to the tire circumferential direction set to 10 °.
[0089]
  Here, when the area between the right auxiliary groove 22 and the left auxiliary groove 22 between the tire equatorial plane CL is defined as an area between the left and right auxiliary grooves, the first lateral groove 16 is disposed in the area between the left and right auxiliary grooves. The portion is a narrow portion 16A that is set narrower than the portion disposed in the region on the outer side in the tire axial direction of the region between the left and right auxiliary grooves. Similarly, in the region between the left and right auxiliary grooves of the second lateral groove 18 The portion to be disposed is a narrow portion 18A that is set narrower than the portion disposed in the region outside the tire axial direction of the region between the left and right auxiliary grooves, and the narrow portion 16A and the narrow portion 18A are: Groove width so that when facing the road surface by load rolling, the opposed groove walls come into contact with each other to form a pseudo circumferential rib 24 (part shown by a two-dot chain line) substantially continuous with the central portion in the tread width direction. Is set.
[0090]
  The groove width of the narrow portion 16A and the groove width of the narrow portion 18A of this embodiment are each set to 1.5 mm.
[0091]
  Here, it is preferable to set the width (average value) RW of the pseudo circumferential rib 24 in a range of 5 to 25% of the tread width TW. In this embodiment, since the width RW of the pseudo circumferential rib 24 is 18 mm and the tread width TW is 167 mm, the width RW of the pseudo circumferential rib 24 is 11% of the tread width TW.
[0092]
  The vicinity of the acute angle end portion with the smallest angle of the triangular small block 20 </ b> A protrudes into the circumferential main groove 14.
[0093]
  Here, the protrusion amount S of the apex of the triangular block 20 into the circumferential main groove 14 is preferably set within a range of 30 to 70% of the groove width SW of the circumferential main groove 14.
[0094]
  In the present embodiment, the protrusion amount S of the apex of the triangular block 20 into the circumferential main groove 14 is set to 52% of the groove width SW of the circumferential main groove 14.
[0095]
  As shown in FIG. 2, a chamfer 26 whose height gradually decreases toward the apex is provided in the vicinity of the acute angle end portion with the smallest angle of the triangular small block 20A.
[0096]
  As shown in FIG. 1, the start position 26 </ b> A of the chamfer 26 is located closer to the tire equatorial plane CL than the groove wall on the tire equatorial plane CL side of the circumferential main groove 14 (the bottom side of the triangular block 20).
[0097]
  The triangular block 20 is formed with a plurality of linear sipes 28 extending substantially along the longitudinal direction of the triangular block 20.
[0098]
  The number of sipes 28 arranged in the tire circumferential direction gradually increases from the apex of the triangle toward the bottom, and the sipe interval in the tire circumferential direction is set to be substantially constant.
[0099]
  The width of the sipe 28 of the triangular block 20 is set to 0.5 mm.
[0100]
  A plurality of third lateral grooves 30 extending from the circumferential main groove 14 toward the tread end 12E are formed on the outer side in the tire axial direction of the circumferential main groove 14 in the tire circumferential direction.
[0101]
  Therefore, a plurality of shoulder blocks 32 defined by the circumferential main groove 14 and the third lateral groove 30 are arranged on the outer side in the tire axial direction of the circumferential main groove 14 in the tire circumferential direction.
[0102]
  In the third lateral groove 30 of the present embodiment, the first lateral groove 16 and the second lateral groove 18 are extended toward the tread end 12E, and the extended first lateral groove 16 and second lateral groove 18 are mutually connected. It has a crossed shape.
[0103]
  Therefore, the third lateral groove 30 has the narrowest width in the center portion in the tire axial direction, and the groove width gradually increases toward the tire equatorial plane CL and toward the tread end 12E.
[0104]
  Since the third lateral groove 30 has a shape as described above, the tread planar view shape of the shoulder block 32 has a hexagonal shape.
[0105]
  The shoulder block 32 is formed with a plurality of linear sipes 34 extending substantially in the same direction as the sipes 28 of the triangular blocks 20 adjacent in the tire axial direction.
[0106]
  The number of sipe 34 arranged in the tire circumferential direction gradually increases from the circumferential main groove 14 side toward the tread end 12E, and the sipe interval in the tire circumferential direction is set to be substantially constant.
[0107]
  The width of the sipe 34 of the shoulder block 32 is set to 0.5 mm.
[0108]
  In the pneumatic tire 10 of the present embodiment, the negative rate of the tread 12 is set to 30.5%.
(Function)
  First, since the pair of circumferential main grooves 14 extending substantially in parallel along the tire circumferential direction are arranged in the tread 12, basic wet hydroplaning performance and skid performance on ice and snow can be ensured.
[0109]
  Further, by arranging the pair of circumferential main grooves 14 in the tread 12, three block rows are roughly formed, and the central region between the pair of circumferential main grooves 14 is defined with respect to the performance on ice. Effectively, both side regions on both sides can be set to be effective for performance on snow.
[0110]
  Since the plurality of first lateral grooves 16 and second lateral grooves 18 are provided in the tread 12, a block edge component necessary for running on snow can be ensured.
[0111]
  Since the plurality of triangular blocks 20 are arranged opposite to each other so that the apex having the smallest angle and the base opposite to the apex are alternately arranged in the tire circumferential direction, the base of the triangular block 20 is arranged. Make sure the ground is in contact with the ground and make friction with the icy road surface by surface contact. The vicinity of the top of the triangular block 20 moves at the time of ground contact, and the vicinity of the bottom of another adjacent triangular block 20 contacts the ground by the wiper effect. By removing the pseudo water film, the vicinity of the bottom of another adjacent triangular block 20 can be reliably grounded to the road surface, and the braking performance and traction performance on ice can be improved.
[0112]
  The triangular block 20 of the present embodiment is divided in the tire axial direction by the auxiliary groove 22 and has a block rigidity effective for performance on ice and snow.
[0113]
  Further, since the auxiliary groove 22 is provided in the triangular block 20, an edge in the lateral direction (effective for cornering) can be secured, and the cornering performance on ice and snow is improved.
[0114]
  At the time of load rolling, a substantially continuous quasi-circumferential rib 24 is formed on the tire equatorial plane CL. For this reason, the block rigidity of the tread central area is increased, the actual contact area is also increased, the braking performance on the ice and the traction performance are improved, and the block edge component can be obtained by completely comparing with the rib continuous in the tire circumferential direction. In addition, braking performance on snow and traction performance are also improved.
[0115]
  When the width RW of the pseudo circumferential rib 24 is less than 5% of the tread width TW, the function as the pseudo circumferential rib 24 is lowered and the performance on ice is not improved so much.
[0116]
  On the other hand, if the width RW of the pseudo circumferential rib 24 exceeds 25% of the tread width TW, the region having a low negative rate of the pseudo circumferential rib 24 becomes too wide, and there is a concern that the performance on snow may be deteriorated.
[0117]
  When the distance P between the pair of circumferential main grooves 14 is less than 35% of the tread width TW, the area of the central land portion row becomes too small, leading to deterioration in performance on ice.
[0118]
  On the other hand, if the distance P between the pair of circumferential main grooves 14 exceeds 65% of the tread width TW, the rigidity of the land rows on both sides becomes too small, leading to deterioration in uneven wear performance and cornering performance on ice and snow.
[0119]
  Further, if the pair of circumferential main grooves 14 are not arranged substantially symmetrically with the tire equatorial plane CL in between, the size of one of the land sections on both sides becomes too small and the size of the other becomes too large. Will not be balanced.
[0120]
  When the groove width MW of the circumferential main groove 14 is less than 7% of the tread width TW, the drainage performance is lowered, and there is a concern about the deterioration of the wet hydroplaning performance.
[0121]
  On the other hand, if the groove width MW of the circumferential main groove 14 exceeds 20% of the tread width TW, there is a concern about uneven wear (slip-off wear) on both side land portions.
[0122]
  In the third lateral groove 30 that divides the shoulder block 32, if the groove width is the minimum width at the center in the tire axial direction, the noise generated at the time of road contact is less than the constant width, and both side land rows Also, uneven wear (heel and toe wear) is less likely to occur.
[0123]
  Further, the third lateral groove 30 gradually increases its groove width from the tire axial direction central portion toward the tire equatorial plane CL side and the tread end 12E side, so that the groove volume is increased and the performance on snow is ensured. I can do it.
[0124]
  In addition, since the circumferential block rigidity near the center in the tire axial direction of the shoulder block row (both side land portion rows) is increased, it is possible to suppress the falling of the block during ice braking and traction on ice and improve the performance on ice.
[0125]
  Since a plurality of sipes 28 are arranged in the triangular block 20 and a large number of small piece blocks are formed, an effective edge component can be obtained on ice and snow.
[0126]
  Further, in the triangular block 20, the sipe interval in the tire circumferential direction is made substantially constant, so that it is possible to make the rigidity uniform without creating an extremely low rigidity place.
[0127]
  Since the first lateral groove 16 is smaller in angle with respect to the tire axial direction than the second lateral groove 18, it is effective for traction and braking in a region close to straight traveling, and the second lateral groove 18 has the first angle with respect to the tire axial direction. Since it is larger than the horizontal groove 16, it effectively works in traction performance and braking performance during cornering, and therefore, it is possible to exhibit effective performance on ice and snow in all steering angle regions.
[0128]
  The angle θ1 of the first lateral groove 16 is set within a range of 0 to 20 ° close to the tire axial direction in order to improve performance on ice and snow in a state close to straight traveling. In order to form the triangular block 20 in combination with the first lateral groove 16, the angle θ2 of the second lateral groove 18 is set within a range of 10 to 45 °.
[0129]
  If the angle θ2 of the second lateral groove 18 exceeds 45 °, the traction performance and the brake performance are deteriorated.
[0130]
  The third transverse groove 30 extends the first transverse groove 16 and the second transverse groove 18 toward the tread end 12E, and the extended first transverse groove 16 and the second transverse groove 18 intersect each other. Since the groove width gradually increases toward the tire equatorial plane CL and toward the tread end 12E, the water near the center of contact with the first lateral groove is formed. 16, the second lateral groove 18, and the third lateral groove 30 can be efficiently discharged to the outside of the tread end 12 </ b> E.
[0131]
  In addition, when the apex of the triangular block 20 protrudes into the circumferential main groove 14, the protruding portion may be a resistance to the flow of water in the circumferential main groove 14. Since the horizontal groove 30 discharges to the outside of the tread end 12E, a decrease in drainage performance is suppressed.
[0132]
  It also has the effect of suppressing heel and toe wear.
[0133]
  Further, since the lateral groove angle with respect to the tire width direction is different, noise characteristics are improved.
[0134]
  Furthermore, since heel and toe wear is reduced, noise after wear is also improved.
[0135]
  By projecting the apex of the triangular block 20 into the circumferential main groove 14, the block edge component can be increased in the circumferential main groove 14 to improve the performance on snow.
[0136]
  However, since the vicinity of the apex of the triangular block 20 is disadvantageous in terms of rigidity, the chamfer 26 is applied and the depth is gradually increased toward the apex, so that it acts as an edge when penetrating into the snow.
[0137]
  In the triangular block 20, since the start position 26A of the chamfer 26 is arranged on the tire equatorial plane CL rather than the bottom side of the other triangular block 20 adjacent in the tire circumferential direction, the edge enters and exits even on the ground contact surface. This leads to improved performance.
[0138]
  When the protrusion amount S of the apex of the triangular block 20 is less than 30% of the groove width of the circumferential main groove 14, the edge effect is insufficient.
[0139]
  Moreover, if the protrusion amount S of the apex of the triangular block 20 exceeds 70% of the groove width of the circumferential main groove, the drainage of the circumferential main groove 14 may be lowered, and the hydropeening property may be lowered.
[0140]
  When the angle [theta] 3 of the auxiliary groove 22 is 0 [deg.], It acts as a catch in the lateral direction like the circumferential main groove 14. As the angle θ3 of the auxiliary groove 22 increases, the edge component in the front-rear direction increases, which is effective for traction performance and braking performance (especially during steering). However, when the angle exceeds 45 °, an acute angle portion is formed in the triangular block 20. Therefore, 45 ° or less is preferable.
(Other embodiments)
  In addition, although the 3rd horizontal groove 30 of this embodiment has been arrange | positioned on the extended line of the 1st horizontal groove 16 and the 2nd horizontal groove 18, this invention is not restricted to this, The 3rd horizontal groove 30 is In some cases, the first lateral groove 16 and the second lateral groove 18 may not be disposed on the extension line.
[0141]
  In addition, the dimensions, angles, and the like of each part of the above embodiment are examples, and it is needless to say that they can be changed as appropriate without departing from the spirit of the present invention.
(Test example)
  In order to confirm the effect of the present invention, a tire of a conventional example and a tire of an embodiment to which the present invention is applied are prepared, and a snow feeling, a snow brake, a snow traction, an ice feeling, an ice brake, and an ice traction are prepared. Each was compared.
[0142]
  Example tire: The pneumatic tire of the above-described embodiment.
[0143]
  Conventional tire: a pneumatic tire having the tread pattern shown in FIG. The tire size is the same as the tire of the example, and the tread negative rate is set to 30%.
[0144]
  Feeling on snow: Comprehensive evaluation of braking performance, starting performance, straight traveling performance, and cornering performance on a test course on a snowy road surface. The evaluation is represented by an index with the conventional example being 100, and the larger the value, the better the performance.
[0145]
  Snow brake: The braking distance was measured when full braking was performed from 40 km / h on snow. The evaluation is represented by an index with the reciprocal of the braking distance of the conventional example being 100, and the larger the value, the better the performance.
[0146]
  Snow traction: Acceleration time from starting at a distance of 50m on snow was measured. The evaluation is represented by an index in which the reciprocal of the acceleration time of the conventional example is 100, and the larger the value, the better the performance.
[0147]
  Feeling on ice: Comprehensive evaluation of braking performance, starting performance, straight traveling performance, and cornering performance on a test course on an ice sheet. The evaluation is represented by an index with the conventional example being 100, and the larger the value, the better the performance.
[0148]
  Brake on ice: A braking distance was measured when full braking was performed from 20 km / h on an ice plate. The evaluation is represented by an index with the reciprocal of the braking distance of the conventional example being 100, and the larger the value, the better the performance.
[0149]
  Ice traction: Acceleration time from starting at a distance of 20 m on an ice plate was measured. The evaluation is represented by an index in which the reciprocal of the acceleration time of the conventional example is 100, and the larger the value, the better the performance.
[0150]
  Evaluation is as described in Table 1 below.
[0151]
[Table 1]

  As a result of the test, the tire of the example to which the present invention was applied was compared with the tire of the conventional example in all items of snow feeling, snow brake, snow traction, ice feeling, ice brake, and ice traction. On the other hand, it can be seen that the performance is improved.
[0152]
【The invention's effect】
  As described above, according to the pneumatic tire of the present invention, there is an excellent effect that both on-ice performance, on-snow performance, and steering stability can be achieved.
[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 cross-sectional view of a triangular block.
FIG. 3 is a plan view of a tread of a conventional pneumatic tire.
[Explanation of symbols]
        10 Pneumatic tire
        12 tread
        14 Circumferential main groove
        16 First lateral groove (lateral groove)
        16A narrow part
        18 Second lateral groove (horizontal groove)
        18A narrow part
        20 Triangular block (block)
        20A triangular small block (small block)
        20B Trapezoidal small block (small block)
        22 Auxiliary groove
        24 Pseudo circumferential rib
        26 Chamfering
        26A Start position
        28 Sipe
        30 Third lateral groove (horizontal groove)
        TW tread width
        CL tire equator

Claims (12)

By arranging a pair of circumferential main grooves extending substantially parallel to the tread in the tire circumferential direction, a central land portion row in which the tread is arranged between the pair of circumferential main grooves, and the pair of circumferences A plurality of blocks partitioned by a plurality of lateral grooves each extending in a crossing direction of the land portion. A constructed pneumatic tire,
The central land portion row includes a plurality of triangular blocks having a substantially triangular shape that is long in the tire axial direction in a tread plan view, and the apex having the smallest angle and the base opposite to the apex are alternately arranged in the tire circumferential direction. Arranged adjacent to each other along the tire circumferential direction so as to be arranged in opposite directions,
The triangular block is divided into a plurality of small blocks in the tire axial direction by at least one auxiliary groove extending in the tire circumferential direction,
The blocks of the both-side land sections are hexagons in a tread plan view ,
The lateral grooves that define the hexagonal blocks in the tread plan view of the two land side rows have the smallest width at the center in the tire axial direction, and the groove width gradually increases toward the tire equatorial plane side and the tread end side. and it is, the pneumatic tire, characterized in that. When the plurality of triangular blocks are viewed in the tire circumferential direction, the auxiliary groove has a tire equatorial plane on the right side of one triangular block and a tire equatorial plane on the other triangular block adjacent to the one triangular block. Is placed on the left side of
When the area between the left side auxiliary groove and the left side auxiliary groove across the tire equator plane is the left and right auxiliary groove area,
The lateral groove is a narrow portion where the portion disposed in the region between the left and right auxiliary grooves is set to be narrower than the portion disposed in the region on the tire axial direction outer side of the region between the left and right auxiliary grooves,
The narrow portion has a groove width so that when facing the road surface by load rolling, the groove walls facing each other come into contact with each other to form a pseudo circumferential rib substantially continuous in the tire circumferential direction at the center portion in the tread width direction. Is set,
The pneumatic tire according to claim 1, wherein the pseudo circumferential rib has a width set in a range of 5 to 25% of a tread width.   The pair of circumferential main grooves are disposed substantially symmetrically with respect to the tire equatorial plane, and the interval is set to 35 to 65% of the tread width of the tread. Item 3. The pneumatic tire according to Item 2.   The groove width of the pair of circumferential main grooves is set in a range of 7 to 20% of the tread surface width of the tread. The described pneumatic tire. The triangular block is formed with a plurality of sipes extending along the longitudinal direction of the triangular block, and the number of sipes arranged in the tire circumferential direction is gradually increased from the apex toward the base. The pneumatic tire according to any one of claims 1 to 4 . The pneumatic tire according to claim 5 , wherein the sipe interval in the tire circumferential direction is substantially constant. The triangular block is partitioned by alternately arranging first lateral grooves and second lateral grooves inclined at a constant angle and having a larger angle with respect to the tire axial direction than the first lateral grooves. The pneumatic tire according to claim 1 , wherein the pneumatic tire is a tire. The angle of the first lateral groove with respect to the tire axial direction is set within a range of 0 to 20 ° as measured from the acute angle side, and the angle of the second lateral groove with respect to the tire axial direction is set within a range of 10 to 45 °. The pneumatic tire according to claim 7 . The lateral grooves that define the block having a hexagonal shape in a plan view of the treads of the both-side land portion rows are provided such that the first lateral grooves are continuously provided from one tread end toward the other tread end. provided continuously toward the second lateral grooves from one tread edge to the other tread end, claims wherein the first said and transverse grooves second form by intersecting the transverse grooves, characterized in that The pneumatic tire according to claim 7 or claim 8 . The vertex of the triangular block protrudes inward of the circumferential main groove from the bottom of another triangular block adjacent in the circumferential direction, and the protruding portion protruding into the circumferential main groove is at the vertex. The pneumatic tire according to any one of claims 1 to 9, wherein chamfering in which the height gradually decreases is applied. The start position of the chamfer is at least on the tire equator side than the bottom of another triangular block adjacent in the tire circumferential direction,
The amount of projection of the apex of the triangular blocks into the circumferential main groove, the is set within 30% to 70% of the range of the groove width of the circumferential main grooves, that in claim 10, wherein The described pneumatic tire. 12. The angle according to claim 1, wherein an angle of the auxiliary groove with respect to a tire circumferential direction is set in a range of 0 ° to 45 ° as measured from an acute angle side. Pneumatic tires.

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