JP6612606B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire.

  2. Description of the Related Art A pneumatic tire having a land portion in which a tread portion is partitioned in the width direction by a main groove extending in the circumferential direction is known in which a sipe extending in the width direction is provided on the ground contact surface of the land portion. The land portion is designed to improve road surface followability, particularly on wet road surfaces, by reducing rigidity with sipes.

  Generally, the land portion has low rigidity at the end in the width direction and high rigidity at the center in the width direction. For this reason, when forming a sipe, by making the width direction end part a shallow groove and making the width direction center part a deep groove, while preventing an excessive rigidity decrease in the width direction end part of the land part, Appropriate reduction in rigidity is realized at the center in the width direction.

  In order to improve the road surface followability, it is known to form a sipe deeper, but in that case, the rigidity of the land portion will be excessively reduced, causing uneven wear or cracking at the bottom of the sipe groove. Various problems occur such as the occurrence of the problem or the deterioration of the operability.

  As countermeasures, for example, in Patent Documents 1 and 2, the tread portion is configured by a two-layer structure of a cap layer and a base layer that is disposed on the inner diameter side of the cap layer and has a high hardness, and the sipe is shallow. It is disclosed that the depth is changed stepwise into the groove portion and the deep groove portion, and the deep groove portion is cut into the base layer. As a result, the deep groove portion reduces the rigidity of the land portion to improve the road surface followability, and the deep groove portion is positioned on the high hardness base layer, so that the rigidity of the land portion is prevented from excessively decreasing. .

JP 7-61209 A JP-A-5-65003

  By the way, according to Patent Documents 1 and 2, the base layer has a protruding portion that protrudes on the outer diameter side in the center in the width direction of the land portion, and the shallow groove portion of the sipe has a high hardness. It partially overlaps with the raised portion of the layer in the width direction. For this reason, in the shallow groove portion, the rigidity of the portion overlapping with the raised portion is higher than that of the remaining portion and the deep groove portion, and the land portion has uneven rigidity in the width direction. Become.

  Therefore, when the sipe is changed stepwise in the depth direction as in Patent Documents 1 and 2, the rigidity of the land portion is determined when the groove bottom of the sipe is positioned on the base layer having a relatively high hardness. It tends to be uneven in the width direction.

  The present invention has been made in view of the above-mentioned problems, and the rigidity of the land portion is reduced so as to be substantially uniform in the width direction, and the road surface followability is improved, and the operability is deteriorated at the time of large input. It aims at providing a pneumatic tire which can control.

The present invention provides a tread portion including a cap layer positioned at the outermost layer and a base layer which is disposed on the inner diameter side and has high hardness, and a ground land portion which is partitioned in the width direction and constitutes a ground surface. A pneumatic tire formed and formed with a sipe extending in a width direction in the grounded land portion, wherein the sipe includes a first groove portion, a second groove portion that is deeper than the first groove portion, and the first groove portion. A connecting groove connecting the first groove and the second groove; the base layer extending in the width direction along the ground surface; and a groove of the second groove protruding from the base A ridge that overlaps on the bottom side, and a connection ridge that connects the base and the ridge . In the cross-section along the extending direction of the sipe, the connection ridge has an outer diameter. The side contour line intersects the groove bottom line of the connecting groove. There, characterized in that.

  According to the present invention, the sipe having the second groove portion formed as a deep groove allows the second land portion to be easily deformed while appropriately reducing the rigidity of the ground land portion, but when the input to the ground land portion is large. Excessive deformation of the contact land portion can be suppressed by the high hardness base layer overlapping the bottom of the groove. As a result, while improving the road surface followability of the contact land portion on the wet road surface, excessive deformation of the contact land portion is suppressed at the time of a large input (for example, under the action of high G on the dry road surface). Deterioration can be suppressed.

Moreover, in the cross section along the sipe extending direction, the contour line of the raised connecting portion and the groove bottom line of the connecting groove intersect each other, so that the rigidity of the ground contact land portion decreases as the groove depth in the connecting groove increases. Is easily supplemented by a connection ridge having a high hardness. Accordingly, the rigidity of the land portion can be reduced so as to be substantially uniform from the first groove portion to the second groove portion while forming the second groove portion of the deep groove.

  It is preferable that the raised portion overlaps the second groove portion in a range of 20% to 60% of the groove depth from the groove bottom of the second groove portion.

  According to this configuration, by causing the raised portion of the base layer to overlap from the groove bottom of the second groove portion to a range of 20% or more and 60% or less of the groove depth, while appropriately reducing the rigidity of the ground land portion, Excessive deformation of the ground contact area at the time of large input can be suppressed. When the overlap of the raised portion with respect to the groove bottom side of the second groove portion is less than 20%, the rigidity of the ground land portion is likely to be excessively lowered because complementation of rigidity reduction by the second groove portion formed as a deep groove is insufficient. Further, when the overlap exceeds 60%, the rigidity reduction by the second groove portion which is a deep groove is hindered, and the rigidity reduction of the ground contact portion is likely to be insufficient.

In the cross section along the extending direction of the sipe, the contour line of the raised connecting portion and the groove bottom line of the connecting groove portion are substantially symmetric with respect to a direction along the ground contact surface in the ground contact portion. It is preferable that the angles intersect each other, and the difference between the inclined angles of the raised connecting portion and the inclined groove portion is 10 ° or less.

  According to this configuration, the degree to which the groove depth of the connection groove portion becomes deep and the degree to which the raised connection portion rises substantially coincide with each other. Easy to complement. Therefore, the rigidity of the ground contact land portion can be substantially uniform over the tire width direction.

In the cross-section along the extending direction of the sipe, the contour line of the raised connection portion is formed from the end of the groove bottom line on the second groove portion side with respect to the groove bottom line of the connection groove portion. It is preferable to intersect within a range of 20% to 50% of the length of the line.

  According to this configuration, the range in which the groove depth of the connection groove portion becomes deep and the range in which the ridge connection portion bulges can be substantially matched, so that the rigidity reduction of the ground land portion by the connection groove portion can be reduced by the ridge connection portion. Easy to complement.

  The contact land portion is located at an end portion in the width direction of the tread portion, and the width direction length L0 of the contact land portion and the end surface on the tire equator line side of the contact land portion to the second groove portion. The width direction length L1 and the width direction length L2 from the end surface to the end of the second groove portion on the side opposite to the tire equator line are 0.2 ≦ L1 / L0 ≦ 0.5 and 0.8. It is preferable to have a relationship of ≦ L2 / L0 ≦ 0.95.

  According to this structure, a 2nd groove part is located in the center part of the width direction of the grounding land part located in the shoulder side of a tread part. As a result, the rigidity of the central portion, which is relatively higher than the peripheral portion of the ground contact portion, is effectively reduced by the second groove portion, and the rigidity of the peripheral portion is prevented from excessively decreasing. it can.

  When L1 / L0 is less than 0.2 and / or when L2 / L0 exceeds 0.95, the second groove portion becomes longer in the width direction of the ground land portion. Tends to fall excessively. In addition, when L1 / L0 exceeds 0.5 and / or when L2 / L0 is less than 0.8, the second groove portion is shortened in the width direction of the ground land portion. It is easy to lack the rigidity reduction.

  The contact land portion is located at an end in the width direction of the tread portion, and the raised connection portion located on the anti-tire equator line side is accompanied by a drop in the inner diameter side of the contact surface at the end portion. It is preferable that an overlapping range of the increasing protruding portion with respect to the groove bottom side of the second groove portion is located at a position reaching 60% of the groove depth from the groove bottom of the second groove portion.

  According to this configuration, it is possible to prevent an excessive increase in the overlap range of the second groove portion and the raised portion due to the radial depression of the tread portion toward the shoulder side, and thereby, due to the second groove portion. The raised portion does not hinder an appropriate reduction in the rigidity of the ground land portion.

  According to the pneumatic tire according to the present invention, by reducing the rigidity of the land portion substantially uniformly over the width direction, it is possible to suppress the deterioration of the maneuverability at the time of large input while improving the road surface followability. .

The top view which lowers and shows the tread pattern formed in the tread part of the pneumatic tire concerning one embodiment of the present invention. Sectional drawing in the II-II line of FIG.

  Embodiments according to the present invention will be described below with reference to the accompanying drawings. In addition, the following description is only illustrations essentially and does not intend restrict | limiting this invention, its application thing, or its use. Further, the drawings are schematic, and the ratio of each dimension is different from the actual one.

  FIG. 1 is a plan view showing a developed tread portion 2 of a pneumatic tire 1 according to an embodiment of the present invention, and shows only one side with respect to the tire equator line CL. As shown in FIG. 1, the tread portion 2 includes a first main groove 21 and a second main groove 22 extending in the tire circumferential direction in order from the tire equator line CL side to the tire width direction outer side toward the tire radial direction inner diameter side. It is recessed. The tread portion 2 is partitioned into a plurality of land portions 30 in the tire width direction by the first main groove 21 and the second main groove 22.

  Specifically, the plurality of land portions 30 are defined by the center land portion 31, the first main groove 21, and the second main groove 22 that are partitioned by the left and right first main grooves 21, 21 across the tire equator line CL. It includes a partitioned media land portion 32 and a shoulder land portion 33 partitioned outward in the width direction by the second main groove 22.

  Here, in the present invention, extending in the tire circumferential direction means not only when extending in parallel to the tire circumferential direction, but also in a zigzag shape or inclined with respect to the tire circumferential direction and extending in the tire circumferential direction. Also included. Similarly, the term “extending in the tire width direction” includes not only the case of extending in the tire width direction but also the case of extending in the tire width direction in a zigzag shape or inclined with respect to the tire width direction.

  The shoulder land portion 33 has a grounding end EL which is an end portion of the grounding surface when it is grounded on the road surface. A portion on the inner side in the tire width direction from the grounding end EL is referred to as a grounding land portion 33A. A portion outside the EL in the tire width direction will be referred to as a non-ground land portion 33B and will be described below.

  In the non-grounding land portion 33B, first and second slits 41 and 42 extending inward in the tire width direction from an end portion on the outer side in the tire width direction are recessed toward the inner diameter side in the tire radial direction. The first slit 41 terminates in the non-ground land portion 33B. The second slit 42 extends from the non-grounded land portion 33B to the grounded land portion 33A and terminates in the grounded land portion 33A.

  Further, a sipe 50 extending in a substantially arc shape in the tire width direction is recessed in the tire radial direction inner diameter side so as to connect the first slit 41 and the second main groove 22 to the shoulder land portion 33. . The sipe 50 has a smaller groove width than the first and second slits 41 and 42. The groove width of the sipe 50 is set to 0.8 mm, for example.

Figure 2 is a cross-section that put the line II-II of FIG. 1 shows a cross section cut along the shoulder land portion 33 in the sipe 50 and the first slit 41, for convenience, among the tread portion 2 Tread Only the rubber portion is shown, and the belt layer, the carcass ply, the inner ply and the like located on the inner diameter side are omitted.

  As shown in FIG. 2, the tread portion 2 is arranged as a tread rubber portion on the inner diameter side of the cap layer 3 that constitutes the ground contact surface S that is located in the outermost layer and contacts the road surface. And a base layer 10. The cap layer 3 has a JISA hardness of 60 degrees to 70 degrees, and the base layer 10 has a higher hardness than the cap layer 3 and has a JISA hardness of 62 degrees to 74 degrees. Here, the JISA hardness is a value measured at 25 ° C. according to JIS K6253 “Durometer Hardness Test (Type A)”.

  The sipe 50 is a so-called open sipe, and both end portions in the tire width direction communicate with the second main groove 22 and the end portion in the tire width direction of the tread portion 2 via the first slit 41. The sipe 50 includes first groove portions 51 and 51 located at both ends of the ground contact land portion 33A in the tire width direction, a second groove portion 52 located at the center of the ground contact land portion 33A in the tire width direction, and both ends of the second groove portion 52. And a pair of connection groove portions 53, 53 connecting the first groove portions 51, 51.

  The second groove part 52 is configured to be deeper than the first groove part 51. The connecting groove 53 extends in a tire radial direction as it advances in the tire width direction so as to connect the first groove 51 and the second groove 52 at an obtuse angle.

  Specifically, the connection groove 53A located on the inner side in the tire width direction is inclined toward the inner diameter side in the tire radial direction as it proceeds from the end in the tire width direction to the outer side in the tire width direction of the first groove 51A located on the inner side in the tire width direction. Extends to the second groove 52. The connecting groove portion 53B located on the outer side in the tire width direction extends obliquely outward in the tire radial direction as it proceeds from the end portion in the tire width direction of the second groove portion 52 toward the outer side in the tire width direction, and is located on the outer side in the tire width direction. 51B has been reached.

  The length L0 of the ground contact portion 33A in the tire width direction is the length L1 from the end surface of the ground contact land portion 33A on the tire equator line CL side to the second groove 52, and the tire equator line CL of the ground contact portion 33A. Tire width direction length L2 from the end surface on the side to the end on the anti-tire equator side of the second groove 52 is 0.2 ≦ L1 / L0 ≦ 0.5 and 0.8 ≦ L2 / L0 ≦ 0. The positional relationship between the first groove 51 and the second groove 52 is set so as to have a relationship of 95.

  The base layer 10 includes a base layer base 11 extending in the tire width direction along the contact surface S, a base layer raised portion 12 protruding from the base layer base 11 outward in the tire radial direction, the base layer base 11 and the base layer raised portion. 12 and a pair of base layer raised connection portions 13 that connect the two.

  The thickness of the base layer base portion 11 is set to 5% or more and 30% or less with respect to the total thickness of the tread rubber portion except for portions where the first and second main grooves 21 and 22 are recessed. The base layer raised portion 12 is located so as to overlap the second groove portion 52 of the sipe 50 in a range of 20% to 60% of the groove depth from the groove bottom of the second groove portion 52. That is, the base layer raised portion 12 is cut by the second groove portion 52 of the sipe 50.

  The base layer bump connecting portions 13 are located in a pair on the left and right sides of the base layer bump portion 12. The base layer ridge connecting portion 13A located on the inner side in the tire width direction is inclined and extended toward the inner diameter side in the tire radial direction as the radially outer contour line PL advances from the base layer ridge portion 12 toward the inner side in the tire width direction. 11 is reached. The base layer bump connecting portion 13B located on the outer side in the tire width direction extends to the base layer base portion 11 while being inclined and extended toward the inner diameter side in the tire radial direction as the contour line PL proceeds from the base layer raised portion 12 to the outer side in the tire width direction. .

  2, the contour line PL on the tire radial direction outer diameter side of the base layer bump connecting portion 13 intersects the groove bottom line GL of the connecting groove portion 53 of the sipe 50. Specifically, the contour line PL and the groove bottom line GL intersect each other at inclination angles α and β that are substantially symmetrical with respect to the direction along the ground contact surface S in the ground contact land portion 33A.

  More specifically, the contour line PL is within a range of 20% to 50% of the length of the groove bottom line GL from the end of the groove bottom line GL on the second groove portion 52 side with respect to the groove bottom line GL. The angle difference between the inclination angle α of the contour line PL and the inclination angle β of the groove bottom line is 10 ° or less and intersects each other. In other words, the contour line PL is located at a position separated from the end of the groove bottom line GL on the second groove portion 52 side by a length of 20% to 50% of the length of the groove bottom line GL. Crosses GL.

  Further, the ground contact surface S falls toward the inner diameter side in the tire radial direction as it goes outward in the tire width direction in the outer region in the tire width direction. As a result, in the ground contact portion 33A of the shoulder land portion 33, the thickness of the cap layer 3 decreases and the thickness of the base layer 10 increases as it goes outward in the tire width direction. That is, in the second groove portion 52 of the sipe 50, the ratio in the depth direction occupied by the base layer raised portion 12 overlapping the groove bottom increases.

  The base layer bump connecting portion 13 is disposed at a position where the overlap range of the base layer raised portion 12 with respect to the second groove portion 52 reaches a range of 60% of the groove depth from the groove bottom of the second groove portion 52. Thus, the overlap of the base layer raised portion 12 with respect to the second groove portion 52 does not exceed 60%. For this reason, the base layer 10 does not occupy the tread portion 2 excessively in the ground contact land portion 33A.

  According to the pneumatic tire demonstrated above, there exist the following effects.

  According to the present invention, when the sipe 50 having the second groove portion 52 formed as a deep groove reduces the rigidity of the ground land portion 33A moderately and easily deforms, but the input to the ground land portion 33A is large. Can suppress excessive deformation of the ground land portion 33A by the high hardness base layer 10 overlapping the groove bottom side of the second groove portion 52. As a result, for example, while improving the road surface followability of the ground land portion 33A on a wet road surface, excessive deformation of the ground land portion 33A is suppressed during a large input (for example, under the action of high G on a dry road surface). Deterioration of safety can be suppressed.

  In addition, since the contour line PL of the base layer raised connection portion 13 and the groove bottom line GL of the connection groove portion 53 intersect each other, the reduction in rigidity of the ground land portion 33A due to the increase in the groove depth in the connection groove portion 53 is increased. It is easy to complement by the base layer raised connection 13 of hardness. Thereby, the rigidity of the ground contact portion 33A can be reduced to be substantially uniform from the first groove portion 51 to the second groove portion 52 while forming the deep second groove portion 52.

  Further, the base layer raised portion 12 is overlapped with the second groove portion 52 from the groove bottom of the second groove portion 52 in a range of 20% or more and 60% or less of the groove depth. Can be suppressed moderately, and excessive deformation of the ground contact portion 33A at the time of large input can be suppressed. When the amount of overlap of the base layer raised portion 12 with respect to the groove bottom side of the second groove portion 52 is less than 20%, the rigidity of the ground land portion 33A is insufficient because the rigidity reduction by the second groove portion 52 that is a deep groove is insufficient. Tends to fall excessively. Further, when the overlap amount exceeds 60%, the rigidity reduction by the second groove portion 52 that is a deep groove is hindered, and the reduction of the rigidity of the ground contact land portion 33A is likely to be insufficient.

  Further, as shown in FIG. 2, the contour line PL of the base layer raised connection portion 13 and the groove bottom line GL of the connection groove portion 53 intersect each other at an inclination angle that is substantially symmetric with respect to the direction along the ground plane S. The angle difference between the inclination angles α and β is 10 ° or less. As a result, the degree to which the groove depth of the connection groove portion 53 becomes deep and the degree to which the base layer raised connection portion 13 rises can be substantially matched, so that the rigidity of the ground contact land portion 33A by the connection groove portion 53 can be reduced. It is easy to complement by the layer ridge connection part 13. Accordingly, the rigidity of the ground contact portion 33A can be substantially uniform over the tire width direction.

  Further, the contour line PL of the base layer raised connection portion 13 is 20% of the length of the second groove portion 52 from the end of the groove bottom line GL on the second groove portion 52 side with respect to the groove bottom line GL of the connection groove portion 53. Since the crossing is performed in the range of 50% or less, the range in which the groove depth of the connection groove 53 is deep and the range in which the base layer raised connection part 13 is raised substantially coincide with each other. It is easy to supplement the rigidity reduction of the ground contact land portion 33 </ b> A by the base layer raised connection portion 13.

  Further, the length L0 of the ground contact land 33A in the tire width direction, the length L1 from the second main groove 22 to the tire equator line CL side of the second main groove 22, and the reaction of the second main groove 22 to the second groove 52 are shown. Since the length L2 to the end on the tire equator line side has a relationship of 0.2 ≦ L1 / L0 ≦ 0.5 and 0.8 ≦ L2 / L0 ≦ 0.95, that is, The second groove 52 is located at the center in the width direction of the ground contact land 33A. As a result, the rigidity of the peripheral portion is excessively lowered while the rigidity of the central portion of the ground land portion 33A, which is relatively high in comparison with the peripheral portion, is effectively reduced by the second groove portion 52. Can be suppressed.

  When L1 / L0 is less than 0.2 and / or when L2 / L0 exceeds 0.95, the second groove portion 52 becomes longer in the tire width direction of the contact land portion 33A. The rigidity of the portion 33A tends to be excessively lowered. When L1 / L0 exceeds 0.5 and / or when L2 / L0 is less than 0.8, the second groove 52 is shortened in the width direction of the ground land portion 33A. The rigidity reduction of the land portion 33A is likely to be insufficient.

  Further, even in the shoulder region where the ground contact surface falls to the inner diameter side in the tire radial direction, in the ground contact land portion 33A, the range in which the base layer raised portion 12 overlaps the groove bottom side of the second groove portion 52 may exceed 60%. Therefore, it is possible to prevent an excessive increase in the overlap range between the second groove portion 52 and the base layer raised portion 12, thereby reducing an appropriate rigidity reduction of the ground contact land portion 33 </ b> A by the second groove portion 52. The raised portion 12 is not hindered.

  In the above embodiment, the configuration of the sipe 50 and the base layer 10 according to the present invention has been described by taking the case where the configuration is applied to the shoulder land portion 33 as an example. However, the present invention is not limited thereto, and is applied to the center land portion 31 or the mediate land portion 32. May be. Further, the present invention can be applied not only to the rib pattern but also to a block pattern further partitioned by a lateral groove.

  In the above embodiment, the sipe 50 is described as an example of an open sipe that communicates with the main groove or slit in the width direction. However, the present invention is not limited to this and may be applied to a closed sipe.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Cap layer 10 Base layer 11 Base layer base 12 Base layer protruding part 13 Base layer protruding connection part 22 2nd main groove 33 Shoulder land part 33A Grounding land part 41 1st slit 50 Sipe 51 1st Groove 52 Second Groove 53 Connection Groove CL Tire Equatorial Line PL Contour Line GL Groove Bottom Line

Claims (6)

A tread portion including a cap layer located on the outermost layer and a base layer that is disposed on the inner diameter side and has a high hardness is formed with a ground land portion that is partitioned in the width direction and constitutes a ground plane. A pneumatic tire in which a sipe extending in the width direction is formed in the grounded land portion,
The sipe is
A first groove,
A second groove that is deeper than the first groove;
A connecting groove connecting the first groove and the second groove,
The base layer is
A base extending in the width direction along the ground plane;
A raised portion that rises from the base and overlaps the groove bottom side of the second groove,
A raised connecting portion that connects the base and the raised portion,
In the cross section along the extending direction of the sipe, the raised connection part is a pneumatic tire in which a contour line on an outer diameter side intersects a groove bottom line of the connection groove part.   2. The pneumatic tire according to claim 1, wherein the raised portion overlaps the second groove portion within a range of 20% to 60% of the groove depth from a groove bottom of the second groove portion. . In the cross section along the extending direction of the sipe, the contour line of the raised connecting portion and the groove bottom line of the connecting groove portion are substantially symmetric with respect to a direction along the ground contact surface in the ground contact portion. Intersect each other at an angle,
The pneumatic tire according to claim 1 or 2, wherein a difference between the inclination angles of the raised connection portion and the connection groove portion is 10 ° or less. In the cross-section along the extending direction of the sipe, the contour line of the raised connection portion is formed from the end of the groove bottom line on the second groove portion side with respect to the groove bottom line of the connection groove portion. The pneumatic tire according to any one of claims 1 to 3, which intersects within a range of 20% to 50% of the length of the line. The ground land portion is located at an end in the width direction of the tread portion,
A width direction length L0 of the ground contact portion, a width direction length L1 from the end surface on the tire equator line side of the ground contact portion to the second groove portion, and an anti-tire equator line side of the second groove portion from the end surface The width direction length L2 to the end of each of the above has a relationship of 0.2 ≦ L1 / L0 ≦ 0.5 and 0.8 ≦ L2 / L0 ≦ 0.95. The pneumatic tire according to any one of the above. The ground land portion is located at an end in the width direction of the tread portion,
The raised connecting portion located on the anti-tire equator line side has an overlap range of the raised portion, which increases as the ground contact surface at the end portion falls toward the inner diameter side, with respect to the groove bottom side of the second groove portion. The pneumatic tire according to any one of claims 1 to 5, which is located at a position reaching 60% of the groove depth from the groove bottom of the two groove portions.

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