JP6204837B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire with improved performance on snow and performance on ice.

  2. Description of the Related Art Conventionally, a pneumatic tire is known in which performance on ice is improved by providing a plurality of sipes on a tread block.

  For example, Patent Document 1 proposes a pneumatic tire that further improves the performance on ice by providing a narrow groove (sub sipe) having a depth of 1 mm or less in addition to the above-described normal sipe (main sipe). ing.

JP 2006-76556 A

  Generally, in winter tires, snow on the road surface is pressed and hardened in the groove of the tread portion to form a snow column, and a driving force on the snow is obtained by a reaction force when shearing this. Therefore, the performance on snow greatly depends on the structure of a basic tread pattern, that is, a main groove extending in the tire circumferential direction and a lateral groove extending in the tire axial direction.

  Even in the tread pattern described in Patent Document 1, it is expected to improve the performance on snow by generating a large snow column shear force by further improving the main groove and the lateral groove.

  The present invention has been devised in view of the above circumstances, and has as its main object to provide a pneumatic tire with improved performance on snow and performance on ice.

  The present invention provides an air having a tread portion having an outer tread end positioned on the outer side of the vehicle when the vehicle is mounted and an inner tread end positioned on the inner side of the vehicle when the vehicle is mounted. An outer tire main groove extending continuously in the tire circumferential direction on the outer tread end side of the tire equator, and between the outer shoulder main groove and the tire equator. An outer middle main groove extending continuously in a zigzag manner in the circumferential direction, and a plurality of outer middle lateral grooves extending between the outer middle main groove and the outer shoulder main groove so as to be inclined with respect to the tire axial direction An outer shoulder land portion divided by the outer shoulder main groove and the outer tread end, the outer shoulder main groove and the outer middle main groove. A plurality of outer middle blocks divided by the outer middle lateral grooves are formed as outer middle land portions arranged in the tire circumferential direction, and the outer middle blocks are formed on the outer side from the outer shoulder main grooves to the inner side in the tire axial direction. An outer middle lug groove extending in a direction opposite to the middle lateral groove and terminating in the outer middle block, a plurality of outer middle main sipes extending along the outer middle lateral groove, and the outer middle main sipe An outer middle sub sipe that is inclined in the opposite direction and has a depth smaller than that of the outer middle main sipe is provided.

  In the pneumatic tire according to the present invention, it is preferable that the outer middle main sipe has an angle of 0 ° to 30 ° with respect to the tire axial direction.

  In the pneumatic tire according to the present invention, it is preferable that the outer middle sub-sipe has an angle of 0 ° to 30 ° with respect to the tire axial direction.

  In the pneumatic tire according to the present invention, it is preferable that a side wall surface of the outer middle sub-sipe has an angle of 0 ° to 10 ° with respect to a normal surface of the middle block.

  In the pneumatic tire according to the present invention, the shoulder land portion includes a plurality of outer shoulder lateral grooves that extend between the outer tread end and the outer shoulder main groove and that are inclined with respect to the tire axial direction. Are divided into a plurality of outer shoulder blocks arranged in the tire circumferential direction, and the outer shoulder blocks include a plurality of outer shoulder main sipes extending along the outer shoulder lateral grooves, and the outer shoulder main sipes. It is desirable that a plurality of outer shoulder sub-sipes that are inclined in the opposite direction and have a depth smaller than that of the outer shoulder main sipes are provided.

  In the pneumatic tire according to the present invention, it is preferable that the outer shoulder main sipe has an angle of 0 ° to 30 ° with respect to the tire axial direction.

  In the pneumatic tire according to the present invention, it is preferable that the outer shoulder sub-sipe has an angle of 0 ° to 30 ° with respect to the tire axial direction.

  In the pneumatic tire according to the present invention, it is preferable that a side wall surface of the outer shoulder sub-sipe has an angle of 0 ° to 10 ° with respect to a normal surface of the shoulder block.

  The pneumatic tire of the present invention has an outer tread end positioned on the vehicle outer side and an inner tread end positioned on the vehicle inner side in the tread portion by designating the mounting direction to the vehicle. The tread portion is provided with an outer shoulder main groove, an outer middle main groove, and an outer middle lateral groove, thereby forming an outer shoulder land portion and an outer middle land portion in which a plurality of outer middle blocks are arranged in the tire circumferential direction. . The outer middle main groove is formed in a zigzag shape, and the traction performance and braking performance on snow are enhanced by the components in the tire axial direction.

  Further, the outer middle block is provided with an outer middle lug groove that extends inward in the tire axial direction from the outer shoulder main groove, inclines in the direction opposite to the outer middle lateral groove, and terminates in the outer middle block. Such an outer middle lug groove generates a large snow column shear force on the snow, and improves the performance on the snow of the pneumatic tire.

  On the other hand, the performance on ice is enhanced by the edge effect generated by the outer middle main sipe and the outer middle sub sipe provided in the outer middle block. Since the outer middle sub sipe is smaller in depth than the outer middle main sipe provided in a normal winter tire, the rigidity of the outer middle block is sufficiently secured. Accordingly, the steering stability performance on the dry road surface is sufficiently ensured, the occurrence of uneven wear is suppressed, and the edge effect of the outer middle sub sipe is maintained for a long time.

It is an expanded view of the tread part which shows one Embodiment of the pneumatic tire of this invention. It is the perspective view which fractured | ruptured a part of outer side middle block of FIG. FIG. 2 is an enlarged development view of an outer middle block and an outer shoulder block of FIG. 1. It is sectional drawing of the outer side middle block of FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a development view of a tread portion 2 of a pneumatic tire (not shown) showing an embodiment of the present invention. As shown in FIG. 1, the pneumatic tire of the present embodiment (hereinafter sometimes simply referred to as “tire”) is suitably used as a studless tire for passenger cars, for example.

  The tire according to the present embodiment includes an asymmetric tread pattern in which the mounting direction of the vehicle is designated. Thereby, the tread portion 2 of the tire has an outer tread end To positioned on the vehicle outer side when the tire is mounted on the vehicle and an inner tread end Ti positioned on the vehicle inner side when the vehicle is mounted. The direction of mounting on the vehicle is displayed, for example, in characters on a sidewall (not shown).

  Each of the “tread ends” To and Ti is when a normal load is loaded on a normal rim that is assembled with a normal rim and filled with a normal internal pressure, and a normal load is applied to a flat surface with a camber angle of 0 degrees. Is defined as the ground contact position on the outermost side in the tire axial direction. The distance in the tire axial direction between the tread ends To and Ti in the normal state is determined as the tread contact width TW. Unless otherwise noted, the dimensions and the like of each part of the tire are values measured in a normal state.

  The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based. For example, “Standard Rim” for JATMA, “Design Rim” for TRA, ETRTO If so, it is "Measuring Rim".

  “Regular internal pressure” is the air pressure that each standard defines for each tire in the standard system including the standard on which the tire is based. “JAMATA” is the “maximum air pressure”, TRA is the table “TIRE LOAD LIMITS” The maximum value described in “AT VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” in the case of ETRTO. When the tire is for a passenger car, the normal internal pressure is 180 kPa.

  “Regular load” is a load determined by each standard for each tire in the standard system including the standard on which the tire is based. “JATMA” is “maximum load capacity”, TRA is “TIRE LOAD” The maximum value described in “LIMITS AT VARIOUS COLD INFLATION PRESSURES”, “LOAD CAPACITY” in the case of ETRTO. When the tire is for a passenger car, the normal load is a load corresponding to 88% of the load.

  The tread portion 2 is provided with a main groove extending continuously in the tire circumferential direction. The main groove of this embodiment includes an outer shoulder main groove 3, an outer middle main groove 4, an inner shoulder main groove 5, and an inner middle main groove 6.

  The outer shoulder main groove 3 is provided on the outer tread end To side of the tire equator C and on the outermost tread end To side of the main grooves. The outer shoulder main groove 3 is, for example, linear. Such an outer shoulder main groove 3 enhances the rigidity in the tire circumferential direction of the land portion outside the vehicle, and improves the straight running stability performance.

  The outer middle main groove 4 is provided at a position between the tire equator C and the outer shoulder main groove 3. The outer middle main groove 4 of the present embodiment has a long side portion 4A inclined to one side with respect to the tire circumferential direction, a length in the tire circumferential direction smaller than the long side portion 4A, and the long side portion 4A. Is formed in a zigzag shape in which short side portions 4B inclined in the opposite direction are alternately arranged. Such an outer middle main groove 4 has a large tire axial component, and contributes to improvement of traction performance and braking performance on snow. The outer middle main groove 4 may have a wavy shape.

  The inner shoulder main groove 5 is provided on the inner tread end Ti side with respect to the tire equator C and on the innermost tread end Ti side among the main grooves. The inner shoulder main groove 5 of this embodiment extends linearly. Such an inner shoulder main groove 5 increases the rigidity in the tire circumferential direction of the land portion on the inner side of the vehicle, and improves the straight running stability performance. The inner shoulder main groove 5 may have a zigzag shape or a wavy shape.

  The inner middle main groove 6 is provided at a position between the tire equator C and the inner shoulder main groove 5. The inner middle main groove 6 of this embodiment extends linearly. Such an inner middle main groove 6 also increases the rigidity in the tire circumferential direction of the land portion inside the vehicle and improves the straight running stability performance. The inner middle main groove 6 may have a zigzag shape or a wavy shape.

  The groove width (groove width measured in a direction perpendicular to the groove center line) W1 to W4 and the groove depth (not shown) of each of the main grooves 3 to 6 can be variously determined according to common practice. The groove widths W1 to W4 of the main grooves 3 to 6 are preferably 1.0 to 7.0% of the tread ground contact width TW, for example. In the present embodiment, the groove width W2 of the outer middle main groove 4 is smaller than the groove width W4 of the inner middle main groove 6, for example. Further, the groove width W1 of the outer shoulder main groove 3 is smaller than the groove width W4 of the inner shoulder main groove, for example. As a result, the rigidity of the land portion outside the vehicle where a large lateral force acts is particularly improved during turning, and the steering stability performance is improved. In the case of the passenger car tire of the present embodiment, the groove depth of each of the main grooves 3 to 6 is preferably 5 to 10 mm, for example.

  The tread portion 2 is divided into an outer middle land portion 10, an outer shoulder land portion 11, an inner middle land portion 12, an inner shoulder land portion 13, and a center land portion 14 by the main grooves 3 to 6. .

  The outer middle land portion 10 is disposed between the outer shoulder main groove 3 and the outer middle main groove 4. The outer middle land portion 10 is provided with a plurality of outer middle lateral grooves 16 extending between the outer middle main groove 4 and the outer shoulder main groove 3. Thereby, the outer middle land portion 10 is formed as a block row in which a plurality of outer middle blocks 10B divided by the outer shoulder main groove 3, the outer middle main groove 4, and the outer middle lateral groove 16 are arranged in the tire circumferential direction. Yes.

  The outer middle lateral groove 16 of the present embodiment extends in a zigzag shape. By providing such an outer middle horizontal groove 16 between the outer shoulder main groove 3 and the outer middle main groove 4, the snow in the outer middle horizontal groove 16 can be grabbed in small steps by the lateral force at the beginning of turning. For this reason, the snow column shear force at the beginning of turning is increased, and the performance on snow is improved.

  The outer middle lateral groove 16 is smoothly continuous with the outer shoulder lug groove 22 via the outer shoulder main groove 3. Thus, a large groove space extending in the tire axial direction is formed by the outer shoulder lug groove 22, the outer shoulder main groove 3, and the outer middle lateral groove 16, so that a large snow column shearing force is exhibited. Note that “smoothly continues” means that the outer middle lateral groove 16 smoothly continues with the outer shoulder lug groove 22 when the outer middle lateral groove 16 is extended outward in the tire axial direction along the groove shape. In the present embodiment, the short side portion 4B is further connected to this groove space (hereinafter, the same applies to the outer shoulder lateral groove 17).

  The outer middle lateral groove 16 has a portion where the groove width W5 gradually increases toward the outer side in the tire axial direction. Thereby, the snow in the outer middle lateral groove 16 is easily discharged outside the outer tread end To via the outer shoulder main groove 3. In the present embodiment, since the groove width W5 gradually increases on the outer shoulder main groove 3 side, the above-described action is more effectively exhibited.

  The groove width W5 of the outer middle lateral groove 16 is preferably 2.0% to 5.0% of the tread ground contact width TW in order to effectively exhibit the above-described action. Similarly, the groove depth (not shown) of the outer middle lateral groove 16 is preferably 3 to 8 mm, and is preferably smaller than the main groove.

  An outer middle lug groove 21 is provided in the outer middle block 10B. The outer middle lug groove 21 is inclined inward in the tire axial direction from the outer shoulder main groove 3 in the direction opposite to the outer middle lateral groove 16 and ends in the outer middle block 10B. Such an outer middle lug groove 21 generates a large snow column shear force on the snow, and improves the performance on the snow of the pneumatic tire.

  In the present embodiment, the outer middle lug groove 21 has a groove width that gradually increases toward the outer side in the tire axial direction. As a result, the snow in the groove is easily discharged using the lateral force during turning, and the performance on snow is further improved.

  The maximum length LA in the tire axial direction of the outer middle lug groove 21 is preferably the tire axis of the outer middle land portion 10 from the viewpoint of effectively exhibiting the above-described action while ensuring the rigidity of the outer middle land portion 10. 30% to 40% of the maximum width WA in the direction. Similarly, the maximum length LB in the tire circumferential direction of the outer middle lug groove 21 is preferably 1.5% to 6.5% of the tread contact width TW.

  The outer middle block 10B is provided with a plurality of outer middle main sipes 31 extending along the outer middle lateral groove 16, and a plurality of outer middle sub-sipes 32 extending in a direction opposite to the outer middle main sipe 31. Yes. The outer middle main sipe 31 is formed in a waveform. “Extending along the outer middle lateral groove 16” means that a virtual line connecting the amplitude centers of the corrugated outer middle main sipes 31 extends along the outer middle lateral groove 16 (hereinafter referred to as outer shoulder mains). The same applies to the sipe 33, the inner middle main sipe 36, the inner shoulder main sipe 38, and the center main sipe 41).

  As already described, the inclination direction of the outer middle main sipe 31 and the outer middle sub sipe 32 depends on the inclination direction of the outer middle lateral groove 16. The inclination direction of the outer middle lateral groove 16 is not limited to the form shown in FIG. 1, and may be a form inclined in the opposite direction. Therefore, the inclination directions of the outer middle main sipe 31 and the outer middle sub sipe 32 are also changed in accordance with the change in the inclination direction of the outer middle lateral groove 16.

  FIG. 2 shows an outer middle block 10B with a part thereof broken. The outer middle main sipe 31 has a depth equivalent to a sipe provided in a normal winter tire. That is, the depth of the outer middle main sipe 31 is preferably 50% or more, more preferably 60% or more of the groove depth of the outer middle lateral groove 16, for example.

  The outer middle sub sipe 32 is formed in a straight line and intersects the outer middle main sipe 31 in the outer middle block 10B. The depth of the outer middle sub sipe 32 is shallower than the depth of the outer middle main sipe 31.

  In general, the tread surface of the tread portion 2 of a new pneumatic tire is smoothly formed by a vulcanization mold. Therefore, there is a possibility that sufficient on-ice performance cannot be exhibited at the initial stage of traveling. However, in the present embodiment, the on-ice performance is enhanced by the sufficient edge effect that the outer middle sub-sipe 32 exhibits in the initial traveling. On the other hand, when the outer middle sub-sipe 32 disappears due to wear, minute irregularities are formed on the tread surface of the tread portion 2, and the on-ice performance is maintained by the edge effect. (The same applies to the outer shoulder sub-sipe 35, the inner middle sub-sipe 37, the inner shoulder sub-sipe 40, and the center sub-sipe 42).

  The on-ice performance is enhanced by the edge effect generated by the outer middle main sipe 31 and the outer middle sub sipe 32 provided in the outer middle block 10B. Since the outer middle sub sipe 32 is smaller in depth than the outer middle main sipe 31, the rigidity of the outer middle block 10B is sufficiently secured. Therefore, the steering stability performance on the dry road surface is sufficiently ensured, the occurrence of uneven wear is suppressed, and the edge effect of the outer middle sub sipe 32 is maintained for a long time.

  In the present embodiment, the outer middle main sipes 31a, 31b, and 31c terminate in the outer middle block 10B so that the rigidity of the outer middle block 10B does not decrease locally around the outer middle lug groove 21. Due to the outer middle main sipes 31a, 31b, and 31c, the edge effect generated in the outer middle block 10B tends to be reduced. However, since the outer middle sub-sipe 32 generates a sufficient edge effect particularly when a new tire is used, the performance on ice of the pneumatic tire is enhanced.

  FIG. 3 shows the outer middle land portion 10 and the outer shoulder land portion 11. The outer middle main sipe 31 has an angle α1 of 0 ° to 30 ° with respect to the tire axial direction. The “angle α1 with respect to the tire axial direction of the outer middle main sipe 31” means an angle with respect to the tire axial direction of an imaginary line connecting the amplitude center of the outer middle main sipe 31 of the waveform (hereinafter referred to as the outer shoulder main sipe 33, The same applies to the inner middle main sipe 36, the inner shoulder main sipe 38, and the center main sipe 41). The outer middle sub sipe 32 has an angle β1 of 0 ° to 30 ° with respect to the tire axial direction.

  The outer middle main sipe 31 having the angle α1 and the outer middle sub sipe 32 having the angle β1 intersect at the tread surface of the outer middle block 10B. Thereby, even when turning in any direction, a sufficient edge component in a direction perpendicular to the traveling direction of the tire is sufficiently secured, and the traction performance and the braking performance on the frozen road are enhanced.

  FIG. 4 shows a cross-sectional shape of the outer middle sub sipe 32. The depth Ds of the outer middle sub-sipe 32 is preferably 0.1 mm to 0.8 mm, for example. When the depth Ds is less than 0.1 mm, a sufficient edge effect may not be obtained. On the other hand, when the depth Ds exceeds 0.8 mm, the rigidity of the outer middle block 10B may be reduced.

  The width Ws of the outer middle sub-sipe 32 is preferably 0.1 mm to 0.8 mm, for example. When the width Ws is less than 0.1 mm, a sufficient edge effect may not be obtained. On the other hand, when the width Ws exceeds 0.8 mm, the rigidity of the outer middle block 10B may be reduced.

  The interval Ps between the outer middle sub-sipes 32 is preferably 0.5 mm to 3.0 mm, for example. When the distance Ps is less than 0.5 mm, the rigidity of the outer middle block 10B may be reduced. On the other hand, when the interval Ps exceeds 3.0 mm, there is a possibility that a sufficient edge effect cannot be obtained.

  The angle γ of the side wall surface of the outer middle sub-sipe 32 with respect to the tread surface normal V of the outer middle block 10B is preferably 0 ° to 10 °, for example. If the angle γ is less than 0 °, it may be difficult to release the tread portion 2 from the vulcanization mold. As the angle γ is larger, the snow drainage performance is improved, and immediately after running on the snow, an excellent and sufficient edge effect is exhibited and the on-ice grip is improved. On the other hand, when the angle γ exceeds 10 °, a sufficient edge effect may not be obtained on ice.

  As shown in FIG. 1, the outer shoulder land portion 11 is disposed between the outer shoulder main groove 3 and the outer tread end To.

  The outer shoulder land portion 11 is provided with an outer shoulder lateral groove 17 extending between the outer tread end To and the outer shoulder main groove 3. Accordingly, the outer shoulder land portion 11 is formed as a block row in which outer shoulder blocks 11B divided by the outer shoulder main groove 3, the outer tread end To, and the outer shoulder lateral groove 17 are arranged in the tire circumferential direction.

  The outer shoulder lateral groove 17 has a portion where the groove width W5 gradually increases toward the outer side in the tire axial direction. As a result, the snow in the groove is easily discharged using the lateral force during turning, and the performance on snow is further improved. The groove width of the outer shoulder lateral groove 17 is defined by the distance between the groove edges in the direction perpendicular to the groove center line.

  The groove width W6 of the outer shoulder lateral groove 17 is preferably 2.5% to 5.5% of the tread contact width TW in order to effectively generate a snow column shearing force. Similarly, the groove depth (not shown) of the outer shoulder lateral groove 17 is preferably 3 to 8 mm, and is preferably smaller than the main groove.

  The outer shoulder lateral groove 17 is inclined in the opposite direction to the outer middle lateral groove 16. As a result, the lateral forces in the opposite directions generated in the lateral grooves 16 and 17 are canceled out, so that the traveling stability performance is improved.

  The outer shoulder lateral groove 17 is smoothly continuous with the outer middle lug groove 21 via the outer shoulder main groove 3. Accordingly, a large groove space extending in the tire axial direction is formed by the outer middle lug groove 21, the outer shoulder main groove 3, and the outer shoulder lateral groove 17, so that a large snow column shearing force is exerted.

  An outer shoulder lug groove 22 is provided in the outer shoulder block 11B. The outer shoulder lug groove 22 extends outward from the outer shoulder main groove 3 in the tire axial direction and terminates in the outer shoulder block 11B. In the present embodiment, the outer shoulder lug groove 22 has a groove width that gradually decreases inward in the tire axial direction. Further, the outer shoulder block 11B is provided with a narrow groove 25 extending linearly along the tire circumferential direction. The turning effect on ice is enhanced by the edge effect generated by the narrow groove 25.

  The outer shoulder block 11B includes a plurality of outer shoulder main sipes 33 extending along the outer shoulder lateral grooves 17, a plurality of outer shoulder circumferential sipes 34 extending along the tire circumferential direction, and the outer shoulder main sipes 33 in the opposite direction. A plurality of outer shoulder sub-sipes 35 extending in a slanted manner are provided.

  Similar to the outer middle main sipe 31, the outer shoulder main sipe 33 is formed in a waveform. The outer shoulder main sipe 33 has a depth equivalent to a sipe provided in a normal winter tire. That is, the depth of the outer shoulder main sipes 33 is preferably 50% or more, more preferably 60% or more of the groove depth of the outer shoulder lateral groove 17, for example.

  The outer shoulder circumferential sipe 34 is formed in a waveform. The outer shoulder circumferential sipe 34 is provided on the outermost tread end To side of the outer shoulder block 11B. “The outer shoulder circumferential sipe 34 extends along the tire circumferential direction” means that an imaginary line connecting the amplitude centers of the outer shoulder circumferential sipe 34 of the waveform extends along the tire circumferential direction ( The same applies to the inner shoulder circumferential sipe 39).

  The outer shoulder sub sipe 35 is formed in a straight line and intersects with the outer shoulder main sipe 33 in the outer shoulder block 11B. The depth of the outer shoulder sub sipe 35 is smaller than the depth of the outer shoulder main sipe 33.

  The on-ice performance is enhanced by the edge effect generated by the outer shoulder main sipe 33 and the outer shoulder sub sipe 35 provided in the outer shoulder block 11B. Since the outer shoulder sub sipe 35 is smaller in depth than the outer shoulder main sipe 33, the rigidity of the outer shoulder block 11B is sufficiently ensured. Therefore, the steering stability performance on the dry road surface is sufficiently ensured, the occurrence of uneven wear is suppressed, and the edge effect of the outer shoulder sub-sipe 35 is maintained over a long period.

  As shown in FIG. 3, in the present embodiment, the outer shoulder main sipes 33a and 33b are disposed in the outer shoulder block 11B so that the rigidity of the outer shoulder block 11B does not decrease locally around the outer shoulder lug groove 22. Terminate with Due to the outer shoulder main sipes 33a and 33b, the edge effect generated in the outer shoulder block 11B tends to be reduced. However, since the outer shoulder sub-sipe 35 generates a sufficient edge effect especially when a new tire is used, the performance on ice of the pneumatic tire is enhanced.

  The outer shoulder main sipe 33 has an angle α2 of 0 ° to 30 ° with respect to the tire axial direction. The outer shoulder sub sipe 35 has an angle β2 of 0 ° to 30 ° with respect to the tire axial direction.

  The outer shoulder main sipe 33 having the angle α2 and the outer shoulder sub sipe 35 having the angle β2 intersect at the tread surface of the outer shoulder block 11B. Thereby, even when turning in any direction, a sufficient edge component in a direction perpendicular to the traveling direction of the tire is sufficiently secured, and the traction performance and the braking performance on the frozen road are enhanced.

  The depth, width, and interval of the outer shoulder sub sipe 35 and the angle of the side wall surface with respect to the tread surface normal of the outer shoulder block 11B are the same as those of the outer middle sub sipe 32 shown in FIG.

  As shown in FIG. 1, the inner middle land portion 12 is disposed between the inner shoulder main groove 5 and the inner middle main groove 6. The inner middle land portion 12 is provided with an inner middle lateral groove 18 extending between the inner shoulder main groove 5 and the inner middle main groove 6. Thereby, the inner middle land portion 12 is formed as a block row in which inner middle blocks 12B divided by the inner shoulder main groove 5, the inner middle main groove 6, and the inner middle lateral groove 18 are arranged in the tire circumferential direction.

  The inner middle lateral groove 18 extends in a zigzag shape. By providing such an inner middle lateral groove 18 between the inner shoulder main groove 5 and the inner middle main groove 6, the snow in the inner middle lateral groove 18 can be gripped in small steps by lateral force at the initial turning. For this reason, the snow column shear force at the beginning of turning is increased, and the performance on snow is improved.

  The inner middle lateral grooves 18 are alternately arranged in the tire circumferential direction with respect to the outer middle lateral grooves 16. For this reason, since the snow column shear force by both the lateral grooves 16 and 18 arises alternately, the performance on snow improves. Note that “alternately arranged in the tire circumferential direction” means that the projection area in the tire axial direction of each inner middle lateral groove 18 and the projection area in the tire axial direction of the outer middle lateral groove 16 do not overlap each other. It is.

  In the present embodiment, the inner middle lateral groove 18 is arranged in the opposite direction with the outer shoulder lateral groove 17 aligned in the tire circumferential direction. As a result, the inner middle lateral groove 18 and the outer shoulder lateral groove 17 simultaneously generate a snow column shearing force, and the opposite lateral forces generated by each other are equally offset, so that excellent steering stability performance on snow is exhibited. To do. As described above, in the present embodiment, a large snow column shear force can be exhibited at a short pitch by providing a lateral groove that is displaced in the tire circumferential direction and a lateral groove that aligns the tire circumferential position in a balanced manner. Performance is greatly improved.

  The inner middle lateral groove 18 is inclined in the direction opposite to the inner shoulder lateral groove 19. As a result, the lateral forces in the opposite directions generated in the lateral grooves 18 and 19 are canceled out, so that the performance on snow is further improved.

  The groove width W7 of the inner middle lateral groove 18 is preferably 3.0% to 6.0% of the tread ground contact width TW. Similarly, the groove depth (not shown) of the inner middle lateral groove 18 is preferably 3 to 8 mm, and is preferably smaller than the main groove.

  The inner middle block 12 </ b> B is provided with a plurality of inner middle main sipes 36 extending along the inner middle lateral groove 18 and a plurality of inner middle sub-sipes 37 extending in a direction opposite to the inner middle main sipe 36. Yes.

  The inner middle main sipe 36 is formed in a waveform like the outer middle main sipe 31. The inner middle main sipe 36 has a depth equivalent to a sipe provided in a normal winter tire. That is, the depth of the inner middle main sipe 36 is preferably 50% or more, more preferably 60% or more of the groove depth of the inner middle lateral groove 18, for example.

  The inner middle sub sipe 37 is formed in a straight line shape and intersects the inner middle main sipe 36 in the inner middle block 12B. The depth of the inner middle sub sipe 37 is smaller than the depth of the inner middle main sipe 36.

  The on-ice performance is enhanced by the edge effect generated by the inner middle main sipe 36 and the inner middle sub sipe 37 provided in the inner middle block 12B. Since the inner middle sub sipe 37 is smaller in depth than the inner middle main sipe 36, the rigidity of the inner middle block 12B is sufficiently secured. Therefore, the steering stability performance on the dry road surface is sufficiently ensured, the occurrence of uneven wear is suppressed, and the edge effect of the inner middle sub sipe 37 is maintained for a long time.

  The angle of the inner middle main sipe 36 with respect to the tire axial direction is the same as that of the outer middle main sipe 31 shown in FIG. 3, and the angle of the inner middle sub sipe 37 with respect to the tire axial direction is also the same as that of the outer middle sub sipe 32. . The depth, width, and interval of the inner middle sub sipe 37 and the angle of the side wall surface with respect to the tread surface normal of the inner middle block 12B are the same as those of the outer middle sub sipe 32 shown in FIG.

  The inner shoulder land portion 13 is disposed between the inner shoulder main groove 5 and the inner tread end Ti. The inner shoulder land portion 13 is provided with an inner shoulder lateral groove 19 extending between the inner shoulder main groove 5 and the inner tread end Ti. As a result, the inner shoulder land portion 13 is formed as a block row in which inner shoulder blocks 13B divided by the inner shoulder main groove 5, the inner tread end Ti, and the inner shoulder lateral groove 19 are arranged in the tire circumferential direction.

  In the inner shoulder lateral groove 19 of the present embodiment, the groove edge on one side in the tire circumferential direction has a zigzag shape and the groove edge on the other side smoothly extends. As a result, the inner shoulder lateral groove 19 has a portion where the groove width gradually increases toward the outer side in the tire axial direction. For this reason, the snow in the inner shoulder lateral groove 19 is also easily discharged, and the performance on snow is further improved.

  The groove width W8 of the inner shoulder lateral groove 19 is preferably 2.5% to 5.5% of the tread ground contact width TW. Similarly, the groove depth (not shown) of the inner shoulder lateral groove 19 is preferably 3 to 8 mm, and is preferably smaller than the main groove.

  The inner shoulder block 13B is provided with a narrow groove 26 extending linearly in the tire circumferential direction. The turning effect on ice is enhanced by the edge effect generated by the narrow groove 26.

  The inner shoulder block 13B has a plurality of inner shoulder main sipes 38 extending along the inner shoulder lateral groove 19, a plurality of inner shoulder circumferential sipes 39 extending along the tire circumferential direction, and the inner shoulder main sipes 38 in the reverse direction. A plurality of inner shoulder sub-sipes 40 extending in a slanted manner are provided.

  Similar to the outer middle main sipe 31, the inner shoulder main sipe 38 is formed in a waveform. The inner shoulder main sipe 38 has a depth equivalent to a sipe provided in a normal winter tire. That is, the depth of the inner shoulder main sipe 38 is preferably 50% or more, more preferably 60% or more of the groove depth of the inner shoulder lateral groove 19, for example.

  The inner shoulder circumferential sipe 39 is formed in a waveform. The outer shoulder circumferential sipe 39 is provided on the innermost tread end Ti side of the inner shoulder block 13B.

  The inner shoulder sub sipe 40 is formed in a straight line and intersects the inner shoulder main sipe 38 in the inner shoulder block 13B. The depth of the inner shoulder sub sipe 40 is smaller than the depth of the inner shoulder main sipe 38.

  The on-ice performance is enhanced by the edge effect generated by the inner shoulder main sipe 38 and the inner shoulder sub sipe 40 provided in the inner shoulder block 13B. Since the inner shoulder sub-sipe 40 is smaller in depth than the inner shoulder main sipe 38, the inner shoulder block 13B has sufficient rigidity. Therefore, the steering stability performance on the dry road surface is sufficiently ensured, the occurrence of uneven wear is suppressed, and the edge effect of the inner shoulder sub-sipe 40 is maintained for a long time.

  The angle of the inner shoulder main sipe 38 with respect to the tire axial direction is the same as that of the outer shoulder main sipe 33 shown in FIG. 3, and the angle of the inner shoulder sub sipe 40 with respect to the tire axial direction is also the same as that of the outer shoulder sub sipe 35. . The depth, width, and interval of the inner shoulder sub-sipe 40 and the angle of the side wall surface with respect to the tread surface normal of the inner shoulder block 13B are the same as those of the outer middle sub-sipe 32 shown in FIG.

  The center land portion 14 is disposed between the outer middle main groove 4 and the inner middle main groove 6. The center land portion 14 is provided with a center lateral groove 20 that extends between the outer middle main groove 4 and the inner middle main groove 6. Thereby, the center land portion 14 is formed as a block row in which center blocks 14B divided by the outer middle main groove 4, the inner middle main groove 6, and the center lateral groove 20 are arranged in the tire circumferential direction.

  The center lateral groove 20 has a portion where the groove width W9 gradually increases toward the outer side in the tire axial direction. As a result, the snow in the groove is easily discharged using the lateral force during turning, and the performance on snow is further improved.

  The center lateral groove 20 of the present embodiment communicates with the outer middle main groove 4 at the short side portion 4B. As a result, a continuous snow column is formed from the center lateral groove 20 to the short side portion 4B, and the performance on snow is improved.

  The groove width W9 of the center lateral groove 20 is preferably 1.5% to 4.5% of the tread grounding width TW in order to effectively exhibit the above-described action. Similarly, the groove depth (not shown) of the center lateral groove 20 is preferably 3 to 8 mm, and is preferably smaller than the main groove.

  The center block 14B is provided with a plurality of center main sipes 41 extending along the center lateral grooves 20 and a plurality of center sub sipes 42 extending in a direction opposite to the center main sipes 41.

  Similar to the outer middle main sipe 31, the center main sipe 41 is formed in a waveform. The center main sipe 41 has a depth equivalent to a sipe provided in a normal winter tire. That is, the depth of the center main sipe 41 is preferably 50% or more, more preferably 60% or more of the groove depth of the center lateral groove 20, for example.

  The center sub sipe 42 is formed in a straight line shape and intersects the center main sipe 41 in the center block 14B. The depth of the center sub sipe 42 is shallower than the depth of the center main sipe 41.

  The on-ice performance is enhanced by the edge effect generated by the center main sipe 41 and the center sub sipe 42 provided in the center block 14B. Since the center sub sipe 42 is smaller in depth than the center main sipe 41, the rigidity of the center block 14B is sufficiently secured. Therefore, the steering stability performance on the dry road surface is sufficiently ensured, the occurrence of uneven wear is suppressed, and the edge effect of the center sub sipe 42 is maintained for a long time.

  The angle of the center main sipe 41 with respect to the tire axial direction is the same as that of the outer shoulder main sipe 33 shown in FIG. 3, and the angle of the center sub sipe 42 with respect to the tire axial direction is also the same as that of the outer shoulder sub sipe 35. The depth, width, and spacing of the center sub sipe 42 and the angle of the side wall surface with respect to the normal surface of the center block 14B are the same as those of the outer middle sub sipe 32 shown in FIG.

  The land ratio of the tread portion 2 of the present embodiment having the above configuration is desirably 60% to 75%, for example. If the land ratio is less than 60%, the rubber volume is insufficient, and the wear resistance on the dry road surface may be reduced. On the other hand, when the land ratio exceeds 75%, a sufficient snow column shear force cannot be obtained, and the performance on snow may be deteriorated.

  Although the pneumatic tire of the present invention has been described in detail above, the present invention is not limited to the specific embodiment described above, and can be implemented with various modifications.

  A pneumatic tire of size 195 / 65R15 having the basic structure of FIG. 1 was prototyped based on the specifications shown in Table 1, and tested on snow performance and on ice performance (initial frozen road surface turning performance and on-ice grip performance). The test method is as follows.

<Snow performance>
The test tires mounted on the rim 15x6J were mounted on all wheels of a front-wheel drive passenger car with a displacement of 1800 cc under the condition of an internal pressure of 230 kPa, and the steering wheel response at the turn on the snow circuit of the test course, The characteristics related to the feeling of rigidity and grip were evaluated by the driver's sensuality. A result is an index | exponent which sets the comparative example 1 to 100, and shows that it is excellent in the performance on snow, so that a numerical value is large.

<Initial frozen road surface turning performance>
The above-mentioned vehicle traveled on a test course and an initial frozen road surface in an urban area, and characteristics relating to steering wheel response, rigidity, grip, etc. during turning were evaluated by the driver's sensuality. Further, the vehicle entered the vehicle while gradually increasing the speed on the initial frozen road surface of the test course, and the lateral acceleration was measured. A result is an index which sets comparative example 1 as 100, and shows that steering stability performance is excellent, so that a numerical value is large.

<Grip performance on ice>
After driving on the snow circuit of the test course with a vehicle, the vehicle drove on the frozen road surface of the city. A result is an index which makes comparative example 1 100, and it shows that it has a grip on ice higher just after running on snow, so that a numerical value is large.

  As is clear from Table 1, it was confirmed that the pneumatic tires of the examples had significantly improved performance on snow and on ice as compared with the comparative examples.

2 tread portion 3 outer shoulder main groove 4 outer middle main groove 10 outer middle land portion 10B outer middle block 11 outer shoulder land portion 11B outer shoulder block 16 outer middle lateral groove 21 outer middle lug groove 31 outer middle main sipe 32 outer middle sub sipe 33 Outer shoulder main sipe 35 Outer shoulder sub sipe To Outer tread end Ti Inner tread end

Claims (6)

A pneumatic tire having a tread portion having an outer tread end positioned on the outer side of the vehicle when the vehicle is mounted and an inner tread end positioned on the inner side of the vehicle when the vehicle is mounted by specifying the mounting direction on the vehicle. And
In the tread part,
Outer shoulder main groove extending continuously in the tire circumferential direction on the outer tread end side than the tire equator,
Between the outer shoulder main groove and the tire equator, an outer middle main groove extending continuously in a zigzag shape in the tire circumferential direction, and
By providing a plurality of outer middle lateral grooves that extend between the outer middle main groove and the outer shoulder main groove in an inclined manner with respect to the tire axial direction,
An outer shoulder land portion divided by the outer shoulder main groove and the outer tread end;
A plurality of outer middle blocks divided by the outer shoulder main groove, the outer middle main groove, and the outer middle lateral groove are formed as outer middle land portions arranged in the tire circumferential direction,
The outer middle block includes
An outer middle lug groove extending inward in the tire axial direction from the outer shoulder main groove, inclining in the opposite direction to the outer middle lateral groove, and terminating in the outer middle block;
A plurality of outer middle main sipes extending along the outer middle lateral groove;
The outer middle main sipe is inclined in the opposite direction, and an outer middle sub sipe having a smaller depth than the outer middle main sipe is provided ,
The pneumatic tire according to claim 1, wherein a side wall surface of the outer middle sub-sipe has an angle of 5 ° to 10 ° with respect to a normal surface of the middle block .   The pneumatic tire according to claim 1, wherein the outer middle main sipe has an angle of 0 ° to 30 ° with respect to a tire axial direction.   The pneumatic tire according to claim 1 or 2, wherein the outer middle sub-sipe has an angle of 0 ° to 30 ° with respect to a tire axial direction. The shoulder land portion is provided with a plurality of outer shoulder lateral grooves extending between the outer tread end and the outer shoulder main groove and extending in an inclined manner with respect to the tire axial direction. Divided into multiple outer shoulder blocks,
The outer shoulder block includes
A plurality of outer shoulder main sipes extending along the outer shoulder lateral grooves;
The outer shoulder main sipe is inclined in the opposite direction, and a plurality of outer shoulder sub sipes having a smaller depth than the outer shoulder main sipe are provided,
The pneumatic tire according to any one of claims 1 to 3 , wherein a side wall surface of the outer shoulder sub-sipe has an angle of 5 ° to 10 ° with respect to a normal surface of the shoulder block . The pneumatic tire according to claim 4, wherein the outer shoulder main sipe has an angle of 0 ° to 30 ° with respect to a tire axial direction . The pneumatic tire according to claim 4 or 5, wherein the outer shoulder sub-sipe has an angle of 0 ° to 30 ° with respect to a tire axial direction .

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