JP2018039337A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a load durability performance while securing on-snow performance and on-ice performance.SOLUTION: The pneumatic tire comprises: a surface processing part 8 including a plurality of inclined narrow grooves 8A provided on a tread surface 2a in a land part 4 and inclined with respect to a tire circumferential direction; sipes 6 provided on the tread surface 2a in the land part 4, extended along a tire width direction, crossed with the inclined narrow grooves 8A in the surface processing part 8, arranged in plural numbers in the tire circumferential direction and separated at the middle of the extension along the tire width direction thereof; and recessed parts 7 which are separated from separated end parts 6a of the sipes 6 at places where the plurality of sipes 6 arranged in the tire circumferential direction on the tread surface 2a are separated and are extended along the tire circumferential direction and are provided to intersect with the inclined narrow grooves 8 of the surface processing part 8. A depth D1 from the tread surface 2a of the sipes 6, a depth D2 from the tread surface 2a of the recessed parts 7 and a depth D3 from the tread surface 2a of the inclined narrow grooves 8A of the surface processing part 8 satisfy a relational expression: D3<D2<D1.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pneumatic tire.

  Conventionally, for example, in a pneumatic tire described in Patent Document 1, a small hole and a sipe are provided on a tread surface of a land portion, and a sipe is separated in the tire width direction in the center of the land portion, and a small hole is provided therebetween. ing.

  In addition, for example, the pneumatic tire described in Patent Document 2 includes a sipe that extends in the tire width direction and juxtaposed in the tire circumferential direction, and a shoulder block that intersects the sipe and extends in the tire circumferential direction. A secondary groove is provided.

  For example, in the pneumatic tire for snowy and snowy roads described in Patent Document 3, a plurality of blocks are defined on the tread portion, a plurality of sipes are provided on the tread portion, and a plurality of thin cells shallower than the sipes are provided on the tread surface of the block. Grooves are formed, and the angle of these narrow grooves with respect to the tire circumferential direction is shown to be 42 ° or more and 60 ° or less. By forming the narrow groove on the tread surface, the braking / driving performance on the icy road at the early stage of wear is improved, and by eroding the narrow groove at an early stage, the original characteristics of the tread rubber can be exhibited at an early stage. .

JP 2011-240761 A JP 2013-189128 A JP 2004-034903 A

  When the sipe is separated in the tire width direction at the center of the land portion as in the pneumatic tire described in Patent Document 1, the block rigidity is ensured or the sipe is prevented from being clogged with snow and ice. be able to. However, in the part where the sipe is separated, the ground pressure is locally higher than the part where the sipe is provided, and cracks are generated from the separated sipe end, or the separated sipe end is chipped. By doing so, there is a problem that load durability performance deteriorates.

  In the pneumatic tire described in Patent Document 1, since a small hole is provided in a portion where the sipe is separated, there is an effect of reducing the contact pressure, but since the sipe is still separated, the sipe It is difficult to improve the load endurance performance without sufficiently suppressing the occurrence of cracks and chips at the ends.

  In the pneumatic tire described in Patent Document 2, since the auxiliary groove divides the shoulder block, drainage is improved and steering stability on a wet road surface is improved. It is difficult to improve the load endurance performance.

  This invention is made | formed in view of the above, Comprising: It aims at providing the pneumatic tire which can improve load endurance performance, ensuring on-ice performance and on-snow performance.

  In order to solve the above-described problems and achieve the object, a pneumatic tire according to one aspect of the present invention includes a circumferential groove extending in the tire circumferential direction and arranged in a plurality in the tire width direction in the tread portion. A land portion defined by at least the circumferential groove and arranged in a plurality in the tire width direction; a surface processing portion including a plurality of inclined narrow grooves provided on a tread surface in the land portion and inclined with respect to the tire circumferential direction; Provided on the tread surface in the land portion, extending along the tire width direction, intersecting the inclined narrow groove of the surface processed portion, separated in the tire circumferential direction and separated along the tire width direction While the sipe and the plurality of sipe arranged in the tire circumferential direction of the tread surface are separated, the sloped portion of the surface processed portion extends along the tire circumferential direction and is separated from the separated end portion of the sipe. Crossing narrow groove A depth D1 from the tread surface of the sipe, a depth D2 from the tread surface of the recess, and a depth from the tread surface of the inclined narrow groove of the surface processed portion. D3 is D3 <D2 <D1.

  The part between the separated sipe is more rigid than the part where the sipe is formed, and the contact pressure received from the road surface at the time of ground contact is locally high, so the end of the separated sipe may be cut or chipped. It becomes easy and load endurance performance falls. On the other hand, according to the present pneumatic tire, the portion between the separated sipes on the tread surface of the land portion is formed with the recesses across the plurality of sipes arranged in the tire circumferential direction. As a result, the rigidity is lowered and the contact pressure is reduced, so that the contact pressure is made uniform compared to other portions, so that the load endurance performance can be improved. Moreover, since the concave portion is separated from the separated end portion of the sipe and does not communicate with the sipe, the situation where the rigidity of the land portion becomes excessively low can be suppressed, and the surface processed portion is provided. Therefore, the rigidity reduction of the land portion can be appropriately adjusted. In addition, the inclined narrow groove and the sipe of the surface processed portion intersect each other, so that the inclined narrow groove is connected at the shortest along the tire width direction while the recess is separated from the separated end of the sipe. It is possible to prevent the rigidity from becoming excessively low and causing breakage or chipping. In addition, the inclined narrow groove and the sipe of the surface processed portion intersect each other, so that the inclined narrow groove is arranged along the tire circumferential direction while the concave portion is separated from the separated end of the sipe. It can suppress that a high part concentrates and a piece and a chip | tip generate | occur | produce. And in obtaining these effects, the depth D1 from the tread surface of the sipe, the depth D2 from the tread surface of the recess, and the depth D3 from the tread surface of the inclined narrow groove of the surface processed portion, The relationship is D3 <D2 <D1. In addition, by providing the recess, the edge component is increased by the opening edge of the recess and the drainage is improved, so that the performance on ice (steering stability on the road surface on ice) can be improved. Moreover, it has snow performance (steering stability performance on the road surface) due to sipes. As a result, the load durability performance can be improved while ensuring the performance on ice and the performance on snow.

  In the pneumatic tire according to one aspect of the present invention, it is preferable that the surface processed portion has an angle of the inclined narrow groove with respect to a tire circumferential direction of 20 ° or more and 70 ° or less.

  According to this pneumatic tire, when the angle of the inclined narrow groove with respect to the tire circumferential direction is 20 ° or more, the inclined narrow groove extends along the tire circumferential direction while the recess is separated from the separated end of the sipe. It can suppress that the part where the ground pressure is arrange | positioned and which is arrange | positioned concentrates, and a chip | tip and a chip | tip generate | occur | produce. Further, when the angle of the inclined narrow groove with respect to the tire circumferential direction is 70 ° or less, the inclined narrow groove is connected in the shortest direction along the tire width direction while the recess is separated from the separated end of the sipe. It is possible to prevent the rigidity from becoming excessively low and causing breakage or chipping. Therefore, load durability performance can be improved because the angle of the inclined narrow groove with respect to the tire circumferential direction is not less than 20 ° and not more than 70 °. In addition, since the angle of the inclined narrow groove with respect to the tire circumferential direction is 20 ° or more and 70 ° or less, the water film removing action and the edge effect are ensured by the inclined narrow groove, so that the performance on ice (steering stability performance on the road surface on ice) And braking performance).

  In the pneumatic tire according to one aspect of the present invention, the recesses are separated in the course of extending in the tire circumferential direction, and each of them is displaced in the tire width direction intersecting the inclination direction of the inclined narrow groove in the surface processed portion. Are preferably arranged.

  According to this pneumatic tire, since the edge component at the end of the recess in the tire circumferential direction increases with respect to the tire circumferential direction by separating the recess and disposing it in the tire width direction, the performance on ice (mainly In addition, the braking performance on the road surface on ice can be improved. Then, by disposing each separated recess in the tire width direction intersecting with the inclination direction of the inclined narrow groove, the end of each recess is prevented from communicating with the inclined narrow groove, and is inclined from the end of the recess. Occurrence of cuts and chips due to the narrow groove can be suppressed, and load durability performance can be improved.

  In the pneumatic tire according to one aspect of the present invention, the land portion has a block that is divided in the tire circumferential direction by a lug groove that intersects with the tire circumferential direction and has an end communicating with the circumferential groove. The recess preferably opens at at least one end of the block in the tire circumferential direction.

  The stepping side where the block begins to contact the road surface when the vehicle is running and the kicking side that is the last to leave the road surface are the positions in the tire circumferential direction, and are subject to heavy loads and are likely to be cut or chipped due to the end of the sipe . According to the present pneumatic tire, the contact pressure at the end of the block can be reduced and the load endurance performance can be improved by extending in the tire circumferential direction so that a recess is opened at the end of the block. Can do. In addition, the drainage performance can be improved by extending in the tire circumferential direction so that a recess is opened at the end of the block. Steering stability on wet roads and on-ice performance (steering stability on icy roads) Performance) can be improved.

  In the pneumatic tire according to one aspect of the present invention, the surface processed portion further includes a plurality of widthwise narrow grooves extending along a tire width direction, and the inclined narrow grooves are separated from the sipe and the sipe. It is preferable to arrange on the tread surface provided with the recess, and to arrange the widthwise narrow groove on the tread surface of the land portion in the tire width direction.

  According to the pneumatic tire, the inclined narrow groove is disposed in the separated portion of the sipe where the ground pressure is relatively high in the land portion and the portion where the concave portion is provided to reduce the ground pressure, while the ground pressure is relatively low in the land portion. Width direction narrow grooves extending in the tire width direction are arranged at the end of the lower tire width direction to increase the edge component in the tire circumferential direction and improve on-ice performance (steering stability and braking performance on the road surface on ice). can do.

  The pneumatic tire according to the present invention can improve the load durability performance while ensuring the performance on ice and the performance on snow.

FIG. 1 is a plan view of a pneumatic tire according to an embodiment of the present invention. FIG. 2 is an enlarged plan view of the pneumatic tire according to the embodiment of the present invention. FIG. 3 is an AA arrow view in FIG. FIG. 4 is an enlarged plan view of another example of the pneumatic tire according to the embodiment of the present invention. FIG. 5 is an enlarged plan view of another example of the pneumatic tire according to the embodiment of the present invention. FIG. 6 is an enlarged plan view of another example of the pneumatic tire according to the embodiment of the present invention. FIG. 7 is an enlarged plan view of another example of the pneumatic tire according to the embodiment of the present invention. FIG. 8 is a chart showing the results of the performance test of the pneumatic tire according to the example of the present invention.

  Embodiments of the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. The constituent elements of this embodiment include those that can be easily replaced by those skilled in the art or those that are substantially the same. Further, a plurality of modifications described in this embodiment can be arbitrarily combined within the scope obvious to those skilled in the art.

  The pneumatic tire according to this embodiment will be described. FIG. 1 is a plan view of the pneumatic tire according to the present embodiment. FIG. 2 is an enlarged plan view of the pneumatic tire according to the present embodiment. FIG. 3 is an AA arrow view in FIG. 4 to 7 are enlarged plan views of other examples of the pneumatic tire according to the present embodiment.

  In the following description, the tire radial direction refers to a direction orthogonal to the rotation axis (not shown) of the pneumatic tire 1, and the tire radial direction inner side refers to the side toward the rotation axis in the tire radial direction, the tire radial direction outer side. Means the side away from the rotation axis in the tire radial direction. Further, the tire circumferential direction refers to a direction around the rotation axis as a central axis. Further, the tire width direction means a direction parallel to the rotation axis, the inner side in the tire width direction means the side toward the tire equator plane (tire equator line) in the tire width direction, and the outer side in the tire width direction means in the tire width direction. The side away from the tire equator. The tire equator plane is a central plane perpendicular to the rotation axis and in the tire width direction, and the tire equator line is a line along the tire circumferential direction of the pneumatic tire 1 on the tire equator plane.

  The pneumatic tire 1 of the present embodiment has a tread portion 2 as shown in FIG. The tread portion 2 is made of a rubber material, exposed at the outermost side in the tire radial direction of the pneumatic tire 1, and the surface thereof becomes the contour of the pneumatic tire 1 as a tread surface 2 a.

  The tread portion 2 is provided with a plurality of circumferential grooves 3 (five in the present embodiment) aligned in the tire width direction that extend along the tire circumferential direction on the tread surface 2a. The circumferential groove 3 has a groove width of 3 mm or more and 15 mm or less and a groove depth (dimension from the opening position of the tread surface 2a to the groove bottom) of 5 mm or more and 15 mm or less.

  In the tread portion 2, a plurality of (six in this embodiment) land portions 4 are formed in the tire width direction by circumferential grooves 3 on the tread surface 2 a. In this embodiment, the land portion 4 on the inner side in the tire width direction than the circumferential groove 3 on both outer sides in the tire width direction is referred to as an inner land portion 4A, and the tire width direction on the outer circumferential direction groove 3 on both outer sides in the tire width direction. The outer land portion 4 is referred to as a shoulder land portion 4B. In FIG. 1, the shoulder land portion 4 </ b> B is shown only in the grounding area, and the outside of the grounding area is omitted.

  Here, the tread surface 2a of the tread portion 2 of the pneumatic tire 1 is formed in the contact area when the pneumatic tire 1 is assembled to a normal rim, filled with a normal internal pressure, and 70% of the normal load is applied. It is an area that contacts a dry flat road surface. The regular rim is “standard rim” defined by JATMA, “Design Rim” defined by TRA, or “Measuring Rim” defined by ETRTO. The normal internal pressure is “maximum air pressure” defined by JATMA, the maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “INFLATION PRESSURES” defined by ETRTO. The normal load is “maximum load capacity” defined by JATMA, the maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “LOAD CAPACITY” defined by ETRTO.

  The land portion 4 is provided with a lug groove 5 on the tread surface 2a. The lug groove 5 extends so as to intersect the tire circumferential direction, and the end portion communicates with the circumferential groove 3. The lug groove 5 refers to a groove width of 1.5 mm to 10.0 mm and a groove depth of 5 mm to 15 mm. The land portion 4 has a block B that is divided in the tire circumferential direction by the circumferential groove 3 and the lug groove 5. The land portion 4 has ribs R that are not divided by the lug grooves 5 in the tire circumferential direction and are continuous in the tire circumferential direction. Of the four inner land portions 4A, one is a rib R and the other three are blocks B. All of the shoulder land portions 4B are blocks B.

  The land portion 4 is provided with a sipe 6 on the tread surface 2a. The sipe 6 extends along the tire width direction and is provided side by side in the tire circumferential direction. The sipe 6 has a groove width of 0.3 mm or more and 1.2 mm or less and a groove depth of the circumferential groove 3 or less (depth D1 from the tread surface 2a of the sipe 6: see FIG. 3). The sipe 6 has a form communicating with the circumferential groove 3 and a form not communicating with the circumferential groove 3. The sipe 6 is formed in a zigzag shape in which a plurality of openings to the tread surface 2a are continuously bent. In this case, the sipe 6 may be a two-dimensional sipe in which the shape in the tread portion 2 from the tread surface 2a to the inner side in the tire radial direction becomes a zigzag shape along the zigzag shape of the tread surface 2a. In addition, a bent three-dimensional sipe may be used. Moreover, the sipe 6 may be formed in a linear shape with continuous openings to the tread surface 2a. In this case, the sipe 6 may be a one-dimensional sipe in which the shape in the tread portion 2 from the tread surface 2a to the inside in the tire radial direction is linear along the straight shape of the tread surface 2a. It may be a dimensional sipe. Therefore, the pneumatic tire 1 of the present embodiment is configured as a studless tire in which the sipe 6 is provided on the tread surface 2a of the land portion 4. And in this embodiment, the sipe 6 contains the form isolate | separated into two in the middle of extending in the tire width direction in the one land part 4, as shown in FIG. 1 and FIG.

  Moreover, the land part 4 is provided with the recessed part 7 in the tread surface 2a. The concave portion 7 is provided to extend along the tire circumferential direction while the plurality of sipes 6 arranged in the tire circumferential direction are separated. The recess 7 is provided apart from the separated end 6 a of the sipe 6. That is, the concave portion 7 is provided so as to extend over the separated portions of the plurality of sipes 6 arranged in the tire circumferential direction in a form not communicating with the sipes 6.

  Moreover, the land part 4 is provided with the surface processing part 8 in the tread surface 2a. The surface processed portion 8 includes a plurality of inclined narrow grooves 8A extending inclined with respect to the tire circumferential direction. In the tread surface 2a, the sipe 6 extending along the tire width direction and the recess 7 extending along the tire circumferential direction intersect with the inclined narrow groove 8A. The inclined narrow groove 8A may or may not open from the end of the tread surface 2a of the land portion 4 to the end. Further, the inclined narrow groove 8A may be formed to extend linearly, be formed to be curved in the middle, or bend to the middle. The extending direction of the inclined narrow groove 8A is defined by a straight line connecting both end portions.

  3, the depth D1 of the sipe 6 from the tread surface 2a, the depth D2 of the recess 7 from the tread surface 2a, and the depth of the inclined narrow groove 8A of the surface processed portion 8 from the tread surface 2a. The relationship of D3 is D3 <D2 <D1.

  Such a form having the sipe 6, the concave portion 7, and the surface processed portion 8 is applied to the land portion 4 at the inner land portion 4 </ b> A and the shoulder land portion 4 </ b> B, and applied at the block B and the rib R.

  As described above, the pneumatic tire 1 of the present embodiment is partitioned in the tread portion 2 by the circumferential grooves 3 extending along the tire circumferential direction and arranged in the tire width direction, and at least the circumferential grooves 3. A plurality of land portions 4 arranged in the tire width direction, a surface processed portion 8 including a plurality of inclined narrow grooves 8A provided on the tread surface 2a of the land portion 4 and inclined with respect to the tire circumferential direction, and a tread surface 2a of the land portion 4 A sipe 6 provided along the tire width direction, intersecting the inclined narrow groove 8A of the surface processed portion 8 and separated in the tire circumferential direction and extending along the tire width direction, and a tread. While the plurality of sipes 6 arranged in the tire circumferential direction of the surface 2a are separated, the sipe 6 is separated from the separated end portions 6a and extends along the tire circumferential direction to form inclined narrow grooves 8A of the surface processed portion 8. A recess 7 provided to intersect, The depth D1 of the sipe 6 from the tread surface 2a, the depth D2 of the recess 7 from the tread surface 2a, and the depth D3 of the inclined narrow groove 8A of the surface processed portion 8 from the tread surface 2a are D3. <D2 <D1.

  The portion between the separated sipe 6 has higher rigidity than the portion where the sipe 6 is formed, and the ground pressure received from the road surface at the time of ground contact is locally high. Chipping is likely to occur and load durability performance is reduced. On the other hand, according to the pneumatic tire 1 of the present embodiment, in the tread surface 2a of the land portion 4, the portion between the separated sipes 6 has the recesses 7 extending over the plurality of sipes 6 arranged in the tire circumferential direction. Since it is formed, rigidity is lowered by the concave portion 7 and the contact pressure is reduced, so that the contact pressure is made uniform compared to other portions, so that the load endurance performance can be improved. And since the recessed part 7 is separated from the separated edge part 6a of the sipe 6 and is not connected to the sipe 6, the situation where the rigidity of the land part 4 becomes too low can be suppressed, and the surface processed part 8 Therefore, the rigidity reduction of the land portion 4 can be appropriately adjusted. Further, the inclined narrow groove 8A of the surface processed portion 8 and the sipe 6 intersect each other, so that the inclined narrow groove 8A extends along the tire width direction while the concave portion 7 is separated from the separated end portion 6a of the sipe 6. Therefore, the rigidity of the land portion 4 is excessively lowered and the cut and chipping can be suppressed. Further, the inclined narrow groove 8A of the surface processed portion 8 and the sipe 6 intersect each other, so that the inclined narrow groove 8A extends along the tire circumferential direction while the recess 7 is separated from the separated end portion 6a of the sipe 6. Therefore, it is possible to prevent the portion having a high ground pressure from being concentrated and being cut or chipped. In obtaining these effects, the depth D1 of the sipe 6 from the tread surface 2a, the depth D2 of the recess 7 from the tread surface 2a, and the tread surface 2a of the inclined narrow groove 8A of the surface processed portion 8 are obtained. And a depth D3 of D3 <D2 <D1. In addition, the provision of the recess 7 increases the edge component due to the opening edge of the recess 7 and improves the drainage performance, thereby improving the performance on ice (the steering stability performance on the road surface on ice). In addition, the sipe 6 provides on-snow performance (steering stability performance on a snowy road surface). As a result, the load durability performance can be improved while ensuring the performance on ice and the performance on snow.

  By the way, it is preferable that the depth D2 from the tread surface 2a of the recessed part 7 is 0.2 mm or more and 3.0 mm or less. When the depth D2 of the concave portion 7 is 0.2 mm or more, it is possible to prevent the concave portion 7 from being crushed at the time of ground contact, and to improve drainage performance. Can be reduced. Moreover, the excessive fall of the rigidity of the land part 4 can be suppressed as the depth D2 of the recessed part 7 is 3.0 mm or less. As a result, the effect of improving the load durability performance while ensuring the performance on ice and the performance on snow can be remarkably obtained.

  In addition, when the load is applied to the land portion 4, the tread surface 2a is cut or chipped due to the sipe 6, and this is more likely to cause the land portion 4 to fall as the height in the tire radial direction of the land portion 4 increases. . However, when the depth D2 of the concave portion 7 is at least 0.2 mm, it contributes to suppressing breakage and chipping caused by the end portion 6a of the sipe 6 separated in the early stage of wear of the land portion 4. When the concave portion 7 disappears due to wear, the height of the land portion 4 in the tire radial direction is reduced, so that the land portion 4 is less collapsed and the occurrence of cuts and chips due to the sipe 6 is reduced. Therefore, the effect of improving the load durability can be remarkably obtained. Further, the cross-sectional shape of the concave portion 7 is preferably a shape having a curved bottom as shown in FIG. 3 in order to suppress cutting and chipping caused by the end portion 6 a of the sipe 6.

  Moreover, it is preferable that the depth D3 from the tread surface 2a of the inclined narrow groove 8A of the surface processing part 8 is 0.1 mm or more and 0.5 mm or less. When the depth D3 of the inclined narrow groove 8A is 0.1 mm or more, it is possible to improve the braking / driving performance on the icy road in the initial stage of wear, and adjust the rigidity reduction of the land portion 4 when the concave portion 7 is provided. can do. Further, when the depth D3 of the inclined narrow groove 8A is 0.5 mm or less, the inclined narrow groove 8A can be worn out at an early stage, and the original characteristics of the rubber of the tread portion 2 can be exhibited at an early stage.

  Moreover, it is preferable that distance Wa of the recessed part 7 and the edge part 6a which the sipe 6 isolate | separated is 0.5 mm or more and 1.5 mm or less. When the distance Wa between the recessed portion 7 and the separated end portion 6a of the sipe 6 is 0.5 mm or more, a situation in which the rigidity of the land portion 4 becomes excessively low can be suppressed, and the end portion 6a of the sipe 6 is caused. It is possible to suppress cutting and chipping. Further, when the distance Wa between the concave portion 7 and the end portion 6a separated from the sipe 6 is 1.5 mm or less, excessive rigidity of the land portion 4 in the portion where the sipe 6 is separated can be suppressed.

  Moreover, it is preferable that the arrangement | positioning space | interval Wb of the inclination narrow groove 8A of the surface process part 8 is 0.4 mm or more and 2.0 mm or less. When the arrangement interval Wb of the inclined narrow grooves 8A is 0.4 mm or more, the ground contact area of the tread surface 2a of the land portion 4 can be secured, and the performance on ice can be secured. Further, when the arrangement interval Wb of the inclined narrow grooves 8A is 2.0 mm or less, the water film removing action and the edge effect by the inclined narrow grooves 8A are ensured, and the performance on ice (steering stability performance and braking performance on the road surface on ice) is improved. Can be secured.

  In the pneumatic tire 1 of the present embodiment, the surface processed portion 8 preferably has an angle θ of the inclined narrow groove 8A with respect to the tire circumferential direction of 20 ° or more and 70 ° or less as shown in FIG.

  According to the pneumatic tire 1, when the angle θ of the inclined narrow groove 8 </ b> A with respect to the tire circumferential direction is 20 ° or more, the inclined narrow groove 8 </ b> A is formed while the recess 7 is separated from the separated end portion 6 a of the sipe 6. Is arranged along the tire circumferential direction, and it is possible to suppress the portion where the contact pressure is high from concentrating and being cut or chipped. Further, when the angle θ of the inclined narrow groove 8A with respect to the tire circumferential direction is 70 ° or less, the inclined narrow groove 8A extends along the tire width direction while the recess 7 is separated from the separated end portion 6a of the sipe 6. The shortest connection and the rigidity of the land portion 4 are excessively lowered, and it is possible to suppress the occurrence of cutting or chipping. Therefore, when the angle θ of the inclined narrow groove 8A with respect to the tire circumferential direction is 20 ° or more and 70 ° or less, the load durability performance can be improved. Moreover, since the angle θ with respect to the tire circumferential direction of the inclined narrow groove 8A is 20 ° or more and 70 ° or less, the water film removing action and the edge effect by the inclined narrow groove 8A are ensured, so the performance on ice (on the road surface on ice) Steering stability performance and braking performance) can be ensured. Note that the angle θ of the inclined narrow groove 8A with respect to the tire circumferential direction is 45 ° in order to obtain the effect of improving the load endurance performance and the effect of ensuring on-ice performance (steering stability performance and braking performance on the road surface on ice). Preferably there is.

  Moreover, in the pneumatic tire 1 of this embodiment, as shown in FIG. 4, the recessed part 7 is isolate | separated and provided in the middle of the tire circumferential direction. And it is preferable that each recessed part 7 is shifted | deviated and arrange | positioned in the tire width direction which cross | intersects the inclination direction of the inclination narrow groove 8A in the surface process part 8, respectively. In FIG. 4, the inclined narrow groove 8 </ b> A is inclined downward to the right, and the respective recesses 7 separated in the tire circumferential direction are arranged shifted to the lower left. Moreover, in FIG. 4, although the recessed part 7 is separated and provided in the middle in the tire peripheral direction, it is not limited to the number of separation.

  According to this pneumatic tire 1, the edge component at the end in the tire circumferential direction of the recess 7 increases with respect to the tire circumferential direction by separating the recess 7 and disposing it in the tire width direction. Performance (mainly braking performance on an ice surface) can be improved. Then, by disposing the separated recesses 7 in the tire width direction intersecting with the inclination direction of the inclined narrow grooves 8A, the end portions of the respective recesses 7 are prevented from communicating with the inclined narrow grooves 8A. It is possible to suppress the occurrence of cuts and chips from the end of the inclined narrow groove 8A, thereby improving the load durability.

  Moreover, in the pneumatic tire 1 of the present embodiment, as shown in FIGS. 5 and 6, when the land portion 4 is the block B, the recess 7 opens to at least one of the ends of the block B in the tire circumferential direction. It is preferable. FIG. 5 shows an opening at one end of the block B in the tire circumferential direction in the recess 7 having the configuration shown in FIG. In FIG. 5, the recesses 7 may be open at both ends of the block B in the tire circumferential direction. Further, FIG. 6 is open to one end of the block B in the tire circumferential direction in one of the separated recesses 7 having the form shown in FIG. In FIG. 6, each of the separated concave portions 7 may be opened at each end of the block B in the tire circumferential direction.

  The stepping side where the block B starts to come into contact with the road surface when the vehicle is running and the kicking side where the block B is finally separated from the road surface are positions at the ends in the tire circumferential direction. Is likely to occur. According to the pneumatic tire 1 of the present embodiment, the contact pressure at the end of the block B can be reduced by extending in the tire circumferential direction so that the recess 7 is opened at the end of the block B, The load endurance performance can be improved. Moreover, by extending in the tire circumferential direction so that the recess 7 is opened at the end of the block B, drainage performance can be improved, steering stability performance on wet road surface and performance on ice (on the road surface on ice) Steering stability performance) can be improved.

  Moreover, in the pneumatic tire 1 of this embodiment, as shown in FIG. 7, it is preferable that the surface processing part 8 further includes a plurality of narrow grooves 8B extending along the tire width direction. And the surface processing part 8 arrange | positions the inclination narrow groove 8A in the tread surface 2a in which the part which the sipe 6 isolate | separated, and the recessed part 7 were provided. Further, the surface processed portion 8 arranges the widthwise narrow groove 8B on the tread surface 2a at the end portion of the land portion 4 in the tire width direction. The width direction narrow groove 8B is disposed on the tread surface 2a of at least one end of the land portion 4 in the tire width direction. Although the form shown in FIG. 7 is based on the form of the recessed part 7 shown in FIG. 2, it is not restricted to this, You may be based on the form of the recessed part 7 shown in FIGS.

  The width direction narrow groove 8B preferably has a depth from the tread surface 2a of 0.1 mm or more and 0.5 mm or less, similarly to the inclined narrow groove 8A. If the depth of the width direction narrow groove 8B is 0.1 mm or more, the braking / driving performance on the icy road in the early stage of wear can be improved, and the rigidity reduction of the land portion 4 when the concave portion 7 is provided is adjusted. can do. Moreover, when the depth of the width direction narrow groove 8B is 0.5 mm or less, the width direction narrow groove 8B can be worn out at an early stage, and the inherent characteristics of the rubber of the tread portion 2 can be exhibited at an early stage. Moreover, it is preferable that the arrangement | positioning space | interval Wc is 0.4 mm or more and 2.0 mm or less similarly to the inclination narrow groove 8A. When the arrangement interval Wc of the width direction narrow grooves 8B is 0.4 mm or more, the ground contact area of the tread surface 2a of the land portion 4 can be secured, and the performance on ice can be secured. Further, when the arrangement interval Wc of the width direction narrow grooves 8B is 2.0 mm or less, the water film removing action and the edge effect by the width direction narrow grooves 8B are ensured, and the performance on ice (steering stability performance and braking performance on the road surface on ice). ) Can be secured.

  According to the pneumatic tire 1, the inclined narrow groove 8 </ b> A is disposed in the land portion 4 where the sipe 6 having a relatively high contact pressure is separated and the recess 7 is provided to reduce the contact pressure. In the tire width direction end where the contact pressure is relatively low, the width direction narrow groove 8B extending in the tire width direction is arranged to increase the edge component with respect to the tire circumferential direction, and the performance on ice (steering stability on the road surface on ice) Performance and braking performance).

  In addition, in one end of the land portion 4 in the tire width direction, the disposition range We in which the width direction narrow groove 8B is disposed is a ratio We / Wd of the land portion 4 with respect to the tire width direction dimension Wd is 5% or more. It is preferable that it is 30% or less. When We / Wd is 5% or more, the edge component with respect to the tire circumferential direction can be increased, and the performance on ice (the steering stability performance and the braking performance on the road surface on ice) can be improved. When We / Wd is 30% or less, the ground contact region of the inclined narrow groove 8A can be secured, and the effect of lowering the contact pressure by the inclined narrow groove 8A can be significantly obtained.

  Moreover, in the pneumatic tire 1 of this embodiment, it is preferable that the recessed part 7 and the surface process part 8 are applied in the land part 4 (shoulder land part 4B) of the tire width direction outermost side. The shoulder land portion 4B is suitable for improving load durability performance while ensuring on-ice performance and on-snow performance because a load is applied during turning.

  Moreover, in the pneumatic tire 1 of this embodiment, it is preferable that the recessed part 7 and the surface process part 8 are applied in the block B of the land part 4. FIG. Since the block B is more collapsed than the rib R and is loaded, it is suitable for improving the load durability while ensuring the performance on ice and the performance on snow.

  Although not clearly shown in the drawing, the sipe 6 may be provided with a plurality of separations in the extending direction instead of one place, and may be provided with the recesses 7 separated from the separated end parts 6a.

  In this example, performance tests regarding performance on ice, performance on snow, drainage performance, and load durability performance were performed on a plurality of types of pneumatic tires having different conditions (see FIG. 8).

  In this performance test, a pneumatic tire (test tire) having a tire size of 195 / 65R15 was assembled on a regular rim of 15 × 6J.

  The method for evaluating the performance on ice is a test vehicle equipped with the above test tire filled with air pressure of 230 kPa (front drive vehicle with a displacement of 1.5 L) running on the test course on the ice surface and controlled by a specialized test driver. Feeling evaluation is performed on performance, lane change performance, cornering performance, etc. This evaluation is performed by index evaluation using the conventional example as a reference (100). This evaluation shows that the higher the index, the better the performance on ice.

  The method for evaluating the performance on the snow is to run the test course on the road surface on the snow with a test vehicle (front drive vehicle with a displacement of 1.5 L) equipped with the above test tire filled with air pressure 230 kPa, and a special test driver controls and drives it. Feeling evaluation is performed on performance, lane change performance, cornering performance, etc. This evaluation is performed by index evaluation using the conventional example as a reference (100). This evaluation shows that the higher the index, the better the performance on snow.

  The drainage performance is evaluated by driving a test track on a wet road with a test vehicle (front drive vehicle with a displacement of 1.5L) equipped with the above test tire filled with air pressure of 230kPa, and a specialized test driver controls and drives it. Feeling evaluation is performed on performance, lane change performance, cornering performance, etc. This evaluation is performed by index evaluation using the conventional example as a reference (100). This evaluation shows that the higher the index, the better the drainage performance.

  The load durability performance is evaluated by filling each tire with air pressure of 180 kPa, using an indoor drum tester (drum diameter: 1707 mm), and controlling the ambient temperature to 38 ± 3 ° C., then the maximum load specified by JATMA A load corresponding to 88% of the load is applied and the vehicle is run for 2 hours at a speed of 81 km / h, and then the load load is increased by 13% every 2 hours, and the running time when the tire breaks is measured. . Then, based on this measurement result, index evaluation using the conventional example as a reference (100) is performed. This evaluation shows that the higher the index, the better the load durability performance.

  8, in the conventional pneumatic tire, as shown in FIG. 1, the sipe is separated in the extending direction, but the recessed portion is not provided in the separated portion. In the pneumatic tires of Comparative Example 1 and Comparative Example 2, a recess is provided in communication with the sipe at a portion where the sipe is separated in the extending direction as shown in FIG. On the other hand, the pneumatic tires of Examples 1 to 8 are provided with a concave portion at a portion where the sipe is separated in the extending direction as shown in FIG. The pneumatic tires of Examples 1 to 5 are in the form shown in FIG. The pneumatic tire of Example 6 has the form shown in FIG. The pneumatic tire of Example 7 has the form shown in FIG. The pneumatic tire of Example 8 has the width direction narrow groove shown in FIG. 7 based on the form shown in FIG. And as shown in the test result of FIG. 8, it turns out that the load tire performance and drainage performance of the pneumatic tires of Examples 1 to 8 are improved while ensuring the performance on snow and the performance on ice.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 2a Tread surface 3 Circumferential groove 4 Land part 4A Inner land part 4B Shoulder land part 5 Lug groove 6 Sipe 6a End part 7 Concave part 8 Surface processed part 8A Inclined narrow groove 8B Width direction narrow groove B Block R rib

Claims (5)

A circumferential groove extending in the tire circumferential direction and arranged in the tire width direction on the tread portion,
A land portion defined by at least the circumferential groove and arranged in a plurality in the tire width direction; and
A surface-processed portion including a plurality of inclined narrow grooves provided on a tread surface in the land portion and inclined with respect to a tire circumferential direction;
Provided on the tread surface in the land portion, extending along the tire width direction, intersecting the inclined narrow groove of the surface processed portion, separated in the tire circumferential direction and separated along the tire width direction. Sipe and
While the plurality of sipes arranged in the tire circumferential direction on the tread surface are separated, the sipe is separated from the separated end portion and extends along the tire circumferential direction to the inclined narrow groove of the surface processed portion. A recess provided to intersect,
With
A depth D1 from the tread surface of the sipe, a depth D2 from the tread surface of the concave portion, and a depth D3 from the tread surface of the inclined narrow groove of the surface processed portion satisfy D3 <D2 <D1. A pneumatic tire.   2. The pneumatic tire according to claim 1, wherein the surface processed portion has an angle of the inclined narrow groove with respect to a tire circumferential direction of 20 ° or more and 70 ° or less.   The said recessed part is isolate | separated in the middle of extending in a tire peripheral direction, and each is arrange | positioned and shifted | deviated to the tire width direction which cross | intersects the inclination direction of the said inclination fine groove in the said surface process part. Pneumatic tire. The land portion has a block that is divided in the tire circumferential direction by a lug groove that intersects the circumferential direction of the tire and communicates with the circumferential groove at an end.
The pneumatic tire according to any one of claims 1 to 3, wherein the concave portion opens at at least one of ends of the block in the tire circumferential direction.   The surface processed portion further includes a plurality of widthwise narrow grooves extending along the tire width direction, and the inclined narrow grooves are disposed on the tread surface provided with the separated portion of the sipe and the recess, The pneumatic tire according to any one of claims 1 to 4, wherein the widthwise narrow groove is disposed on a tread surface of an end portion of the land portion in the tire width direction.

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