JP6174982B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire.

2. Description of the Related Art Conventionally, as a pneumatic tire, a tire having the following configuration is known in order to improve the ground contact property of the tire.
In Patent Document 1, the sidewall profile includes a convex arc portion that is an arc extending outward in the tire radial direction from the maximum width point and whose center is on the tire lumen side, and a concave arc portion having a center on the tire outer side. A pneumatic tire is disclosed.
In Patent Document 2, a recess connected to the shoulder edge and a recess adjacent to the inner side in the tire radial direction of the recess are provided in the buttress region of the shoulder portion, and the shoulder portion of the shoulder portion on the lower volume side is provided with the shoulder There is disclosed a pneumatic tire provided with a convex portion connected to an edge and a convex portion adjacent to the inner side in the tire radial direction of the convex portion.
Patent Document 3 discloses a pneumatic tire having a sipe in which an inclination angle θ formed by a zigzag amplitude center line with respect to a tire circumferential line is 0 to 45 °.
In Patent Document 4, a narrow groove provided continuously in the tread circumferential direction at the tread shoulder portion is disposed from the end of the tread inward in the tread width direction within a range of 0.15 times the tread width. A pneumatic tire is disclosed in which a bent portion in the tread width direction is provided in the middle of the depth direction of the groove, and the groove width of the narrow groove is in the range of 0.5 to 3 mm.

However, in Patent Document 1, since only the shape of the sidewall is devised, there is a limit in improving the ground contact property by reducing the elastic force in the tire radial direction.
In Patent Document 2, as in Patent Document 1, there is a limit to improvement in grounding performance. Moreover, it is only a structure which can be used only with the tire whose tread pattern is asymmetric.
Patent Document 3 merely discloses a sipe that does not contribute to improvement in ground contact. It is impossible to make the rigidity of the block uniform.
In Patent Document 4, there is no disclosure of a configuration that improves the ground contact property or improves the rigidity balance of the tire.

JP 2013-116707 A JP 2011-105041 A JP 2005-145191 A Japanese Patent Laid-Open No. 11-48716

  This invention makes it a subject to improve the rigidity balance of a tire and to improve grounding property.

As a means for solving the above problems, the present invention provides:
A pneumatic tire formed by forming a plurality of sipes in a block constituted by a groove portion composed of a main groove extending in the tire circumferential direction and a lateral groove extending in the tire width direction,
The sipe includes an outer sipe that extends along the outer edge of the block while repeating contact with and separating from the outer edge of the block;
Said outer sipe is a longitudinal cross-sectional shape perpendicular to the groove, the surface of the block toward the tire inner diameter direction, varying Kuraishi gradually the groove side including the outer edge of the block in which the outer sipes along, and the In the direction along the outer edge of the block, the amount of displacement toward the groove portion including the outer edge of the block along which the outer sipe along the outer sipe is changed with reference to the position on the surface of the block .

  With this configuration, when the tire touches the ground, the part closer to the groove than the outer sipe extends while the outer sipe repeats contact and separation along the outer edge of the block, so the position shifts in the direction along the outer edge of the block. Hateful. Further, since the outer sipe is formed toward the tire inner diameter direction while changing the amount of displacement in the direction along the groove portion, the rigidity balance in the portion (block end portion) on the groove portion side than the outer sipe is stabilized, The grounding property can be improved.

  The outer sipe may be formed so that the longitudinal cross-sectional shape is an arc.

  It is preferable that the outer sipe is formed in an arc shape having a larger curvature radius as the distance from the groove portion on the surface of the block increases.

  With this configuration, it is possible to suppress variations in the thickness of the portion on the groove side from the outer sipe of the block, even though the outer sipe repeats contact and separation along the outer edge of the block surface. Therefore, the rigidity balance in the direction along the outer edge of the block can be stabilized, and the grounding property can be improved.

The side surface of the block is formed in an arc shape with a longitudinal radius of curvature R1;
It is preferable that the longitudinal cross-sectional shape of the outer sipe at the position where the position of the outer sipe is closest to the groove portion on the surface of the block is formed in an arc shape having the curvature radius R1.

  With this configuration, it is possible to prevent variation in rigidity from the outer sipe to the groove side portion (block end portion). Further, the radius of curvature R1 can be set such that the size is small and stress is concentrated and cracks are not generated, or conversely the size is large and a desired wiping performance cannot be obtained.

  It is preferable that the longitudinal cross-sectional shape at the position where the outer sipe is farthest from the groove on the surface of the block is formed in an arc shape having a curvature radius R2 larger than the curvature radius R1.

  With this configuration, it is possible to obtain substantially uniform rigidity in any region along the outer edge even though the outer sipe has a shape that repeats contact and separation along the outer edge on the surface of the block.

  The outer sipe preferably has an inner diameter end in the tire radial direction located on the same circumference in the tire circumferential direction.

  With this configuration, the rigidity on the base side of the block end, which is particularly important, can be made uniform.

  The block is preferably a shoulder block.

  With this configuration, it is possible to make the rigidity uniform in the block where the wiping phenomenon is most likely to occur and to suppress the occurrence thereof.

  According to the present invention, since the outer sipe extending along the outer edge of the block and repeatedly contacting and separating from the outer edge is formed, the end of the block is hardly deformed at the time of grounding. Further, the outer sipe is displaced so that the longitudinal cross-sectional shape orthogonal to the groove portion gradually approaches the groove portion side from the surface of the block toward the tire inner diameter direction, and the displacement amount in the direction along the groove portion. Since it is made to change, the dispersion | variation in the rigidity in the direction along the outer edge of the said block edge part can be suppressed. Thereby, it is possible to improve the ground contact property of the tire.

It is a partial development view of the tire concerning this embodiment. (A) is the elements on larger scale of FIG. 1, (b) is the sectional view on the AA line. It is a partial expanded sectional view which shows the modification of the outer side sipe shown in FIG. It is a partial expanded view of the tire which concerns on other embodiment. It is a partial expanded view of the tire which concerns on other embodiment. It is a partial expanded view of the tire which concerns on a prior art example.

  Embodiments according to the present invention will be described below with reference to the accompanying drawings. In the following description, terms indicating specific directions and positions (for example, terms including “up”, “down”, “side”, “end”) are used as necessary. Is for facilitating understanding of the invention with reference to the drawings, and the technical scope of the present invention is not limited by the meaning of these terms. Further, the following description is merely illustrative in nature and is not intended to limit the present invention, its application, or its use. Further, the drawings are schematic, and the ratio of each dimension is different from the actual one.

  FIG. 1 is a partial development view of the tire according to the first embodiment. Four main grooves 2 extending in the tire circumferential direction are formed on the tread surface 1 of the tire at predetermined intervals in the tire width direction. A plurality of lateral grooves 3 intersecting the main groove 2 are formed on the tread surface 1. A plurality of blocks 4 are formed by the main grooves 2 and the lateral grooves 3.

  The block 4 includes a center block 5 formed in the center region in the tire width direction, a shoulder block 6 formed in both side regions, and a mediate block 7 formed between the center block 5 and the shoulder block 6. .

  The side surface of the shoulder block 6 has a corresponding vertical cross-sectional shape passing through the outer edge of the upper surface of the shoulder block 6, a part of a contact circle between the bottom surface of the groove and a plane (vertical surface) extending in the tire radial direction through the outer edge. This is an arc of curvature radius R1.

  A plurality of sipes 8 are formed in each block 4. All of these sipes 8 are formed inside the outer edge on the surface of the block 4, extend in a wavy shape in the tire width direction, and extend perpendicularly to the surface of the block 4 inward in the tire radial direction. However, in addition to the sipe 8 that extends in the tire width direction, the shoulder block 6 is formed with an outer sipe 9 that is positioned outside in the tire width direction and extends in the tire circumferential direction.

  On the surface of the shoulder block 6, the outer sipe 9 repeatedly touches and separates from the outer edge on the outer side of the shoulder block 6 in the tire width direction, and extends along the outer edge here in a corrugated shape.

  The outer sipe 9 is configured as follows toward the inside of the shoulder block 6. That is, as shown by the dotted line in FIG. 2 (b), the outer sipe 9 has a vertical cross-sectional shape at the position closest to the groove (closest approach position) and a vertical cross-sectional shape at the side surface of the shoulder block 6 (cross section in the tire radial direction). Shape) and a curvature radius R1. The curvature radius R1 is preferably R1 = (1-2, preferably 1) × W, where W is the amplitude on the surface of the shoulder block 6 of the outer sipe 9.

  Further, as shown by the solid line in FIG. 2B, the outer sipe 9 is formed such that the longitudinal cross-sectional shape at the position farthest from the groove (the farthest position) has a curvature radius R2 larger than the curvature radius R1. Yes. And between the closest approach position and the most separated position, it is a curved surface in which a curvature radius changes smoothly. Here, the radius of curvature gradually increases from R1 from the closest position to the farthest position, and the curvature radius becomes R2 at the furthest position.

  Further, the outer sipe 9 is located at the deepest position from the surface of the shoulder block 6 having a longitudinal cross-sectional shape on the same circumference in the tire circumferential direction. That is, the deepest position of the outer sipe 9 is a uniform position with respect to the groove. Therefore, it is possible to prevent variations in the rigidity balance in the tire circumferential direction and improve the ground contact.

  As described above, according to the outer sipe 9 having the above-described configuration, the region (contact surface) in contact with the road surface of the tread surface 1 of the tire is more than necessary for the region (block end portion 6a) on the groove side from the outer sipe 9. Can be prevented from being deformed. This is because, since the outer sipe 9 is formed in a waveform, even if the block end portion 6a is deformed in the extending direction, the waveforms interfere with each other and the deformation is prevented.

  Further, since the radius of curvature of the longitudinal cross-sectional shape of the outer sipe 9 increases from the closest position to the farthest position, the thickness of the block end portion 6a does not vary so much and the rigidity is substantially uniform. Can be.

  In particular, a so-called wiping phenomenon occurs in which the force toward the center, that is, the in-plane contraction force, acts on the ground contact surface of the tire and the resulting deformation of the block 4 has a considerable adverse effect on the friction performance. However, since the rigidity in the tire circumferential direction at the block end portion 6a is substantially uniform by the outer sipe 9, the occurrence of the wiping phenomenon can be suppressed (wiping performance can be improved). As a result, it is possible to improve the ground contact property of the tire.

  In the above-described embodiment, the vertical cross-sectional shape of the outer sipe 9 is an arc shape having a radius of curvature R. However, the outer sipe 9 is linear as shown by E1 in FIG. 3, or swells toward the groove as shown by E2 in FIG. An arc shape may be used.

  Here, the contact pressure distribution was compared between a tire in which the outer sipe 9 was formed in the block 4 and a tire in which the outer sipe 9 was not formed. As the test tire, 195 / 65R15 was used and mounted on a standard rim described in JATMA YEAR BOOK. Then, the contact pressure in the surface of the tread portion that contacts the road surface was measured with the maximum load capacity and the corresponding air pressure, and the dispersion of the contact pressure was indicated by an index. Here, the value of Comparative Example 1 is shown as an index with 100 as the value. The smaller the value, the more uniform the contact pressure and the better the contact performance.

比較例１は、サイプ８を図６に示す通常の波形サイプで構成したものである。
実施例１は、外側サイプ９を図３の点線で示す直線状の縦断面形状としたものである（Ｅ１）。
実施例２は、外側サイプ９を図３の実線で示す凹状の縦断面形状としたものである。
実施例３は、外側サイプ９を図３の一点鎖線で示す凸状の縦断面形状としたものである（Ｅ２）。

In Comparative Example 1, the sipe 8 is configured by a normal waveform sipe shown in FIG.
In Example 1, the outer sipe 9 has a linear longitudinal cross-sectional shape indicated by a dotted line in FIG. 3 (E1).
In the second embodiment, the outer sipe 9 has a concave vertical sectional shape indicated by a solid line in FIG.
In Example 3, the outer sipe 9 has a convex longitudinal sectional shape indicated by a one-dot chain line in FIG. 3 (E2).

  As is clear from Table 1, the outer sipe 9 of any type of Examples 1 to 3 exhibited an excellent effect on the ground pressure distribution. In particular, the ground pressure distribution in the niche was uniform in the outer sipe 9 having a straight vertical cross-sectional shape in Example 2.

  In addition, this invention is not limited to the structure described in the said embodiment, A various change is possible.

For example, in the above embodiment, the outer sipe 9 is formed on the outer side of the shoulder block 6 in the tire width direction along the outer edge of the shoulder block 6, but is further formed on the other portion of the shoulder block 6. May be.
In FIG. 4, not only the outer sipe 9 is formed on the outer side of the shoulder block 6 in the tire width direction, but the inner sipe 10 having a similar configuration is formed on the inner side.
In FIG. 5, in addition to the outer sipe 9 and the inner sipe 10, a tread-side sipe 11 and a kick-out sipe 12 having the same form are formed along the outer edges of the other two sides.

  In the above embodiment, only the case where the outer sipes 9 are formed on the shoulder block 6 has been described. However, the outer sipes 9 may be provided on another block 4 (for example, the mediate block 7). In short, it may be provided in a region (tire tread portion) where the tire can be a ground contact surface in contact with the road surface. However, the provision in the shoulder block 6 is a portion that is greatly affected by the deformation of the tire at the time of ground contact, and therefore has an advantage that an effect excellent in the ground contact property can be exhibited.

  In the above embodiment, the outer sipe 9, the inner sipe 10, the stepping-side sipe 11, and the kick-out sipe 12 are formed in a corrugated shape on the surface of the block 4. Good.

DESCRIPTION OF SYMBOLS 1 ... Tread surface 2 ... Main groove 3 ... Horizontal groove 4 ... Block 5 ... Center block 6 ... Shoulder block 7 ... Mediate block 8 ... Sipe 9 ... Outer sipe 10 ... Inner sipe 11 ... Depression side sipe 12 ... Kick-out side sipe

Claims (7)

A pneumatic tire formed by forming a plurality of sipes in a block constituted by a groove portion composed of a main groove extending in the tire circumferential direction and a lateral groove extending in the tire width direction,
The sipe includes an outer sipe that extends along the outer edge of the block while repeating contact with and separating from the outer edge of the block;
Said outer sipe is a longitudinal cross-sectional shape perpendicular to the groove, the surface of the block toward the tire inner diameter direction, varying Kuraishi gradually the groove side including the outer edge of the block in which the outer sipes along, and the A pneumatic tire characterized in that, in a direction along the outer edge of the block, a displacement amount to the groove side including the outer edge of the block along which the outer sipe along the outer sipe is changed with reference to a position on the surface of the block .   The pneumatic tire according to claim 1, wherein the outer sipe is formed such that the longitudinal cross-sectional shape is an arc shape.   3. The pneumatic tire according to claim 2, wherein the outer sipe is formed in an arc shape having a larger curvature radius as the distance from the groove portion increases on the surface of the block. The side surface of the block is formed in an arc shape with a longitudinal radius of curvature R1;
The longitudinal cross-sectional shape of the said outer sipe in the position where the position of the said outer sipe on the surface of the said block is the closest to the said groove part is formed in the circular arc shape of the said curvature radius R1. Or the pneumatic tire of 3.   The longitudinal cross-sectional shape of the outer sipe at the position farthest from the groove on the surface of the block is formed in an arc shape having a radius of curvature R2 larger than the radius of curvature R1. Item 5. The pneumatic tire according to Item 4.   The pneumatic tire according to any one of claims 1 to 5, wherein the outer sipe has an inner diameter end in a tire radial direction located on the same circumference in the tire circumferential direction.   The pneumatic tire according to any one of claims 1 to 6, wherein the block is a shoulder block.

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