JP2008279837A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of shortening the running time in a competition while maintaining wet performance. <P>SOLUTION: On a tread surface 1 in which the rotational direction R of the tire is specified in one direction, an inclined groove 2 including a second inclined groove 3B which extends to a pattern end 1X on the tread surface 1 beyond a tire ground contact end TE while inclining toward the rear in the rotational direction R of the tire from the center to an outside in the axial direction of the tire, is provided at a predetermined pitch in a tire circumference direction TC. On the second inclined groove 3B, more plurality of land parts 6 are partitioned in the tire circumference direction TC. On the pattern end 1X on each land part 6, there is provided a protruding part 7 which protrudes inside the second inclined groove 3B adjacent to the land part 6 at the front in the rotational direction R of the tire. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire having a directional pattern, and more particularly to a pneumatic tire that improves traction performance during cornering.

  Conventionally, as a pneumatic tire capable of running on public roads mainly for use in competitions, as shown in FIG. 6, from the center side of the tread surface 41 toward the rear side in the tire rotation direction R toward the outer side in the tire axial direction. The inclined grooves 43 extending to the pattern end 42 of the tread surface 41 while being inclined are disposed at a predetermined pitch in the tire circumferential direction, and the plurality of land portions 44 are arranged around the tire circumference by the inclined grooves 43. There is known a pneumatic tire formed in a direction (see, for example, Patent Document 1). Since this type of pneumatic tire also travels on public roads, it is regulated by law that the inclined groove 43 extends to the pattern end 42 in order to ensure wet performance.

Such pneumatic tires are required to further reduce the running time during competition on the circuit course, and the proposal of a tire that can further shorten the running time while satisfying the conditions stipulated by the regulations Is always desired.
JP 2001-294020 A

  It is an object of the present invention to provide a pneumatic tire capable of shortening the running time during competition while ensuring wet performance.

  In the pneumatic tire of the present invention that achieves the above object, the tire rotation direction is designated as one direction, and the tire tire extends beyond the tire ground contact edge while inclining toward the rear side in the tire rotation direction from the center side of the tread surface toward the outer side in the tire axial direction. In the pneumatic tire in which inclined grooves extending to the pattern end of the tread surface are arranged at a predetermined pitch in the tire circumferential direction, and a plurality of land portions are sectioned in the tire circumferential direction by the inclined grooves, each land portion portion In the pattern end side, an overhanging portion that protrudes into an inclined groove adjacent to the land portion portion on the front side in the tire rotation direction is provided.

  According to the above-described present invention, the effective contact length of the land portion at the time of circuit course cornering can be increased by the overhanging portion provided on the tire rotation direction side on the pattern end side of the land portion. The corners can be cornered while maintaining the increased accelerator opening for a long time, while the overhang is provided on the pattern end side that does not affect the grounding when driving on public roads. It will not be done. Therefore, it is possible to shorten the running time during competition while ensuring wet performance.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows a tread pattern of an embodiment of the pneumatic tire of the present invention, in which the tire rotation direction R is designated as one direction indicated by an arrow. On the left and right sides of the center line CL of the tread surface 1, left and right inclined grooves 2 extending inclined with respect to the tire width direction are arranged at a predetermined pitch in the tire circumferential direction TC. These left and right inclined grooves 2 are alternately provided in the tire circumferential direction TC while being shifted by a half pitch in the tire circumferential direction TC.

  Each inclined groove 2 extends in a curved shape with a predetermined curvature while being largely inclined toward the rear side in the tire rotation direction R from the starting point A on the center side in the vicinity of the center line CL toward the inner side in the tire axial direction (tread center side). The first inclined groove portion 3A and the first inclined groove portion 3A located on the center side of the tread surface 1 are inclined toward the rear side in the tire rotation direction R toward the outer side in the tire axial direction while exceeding the tire contact point TE and the tread surface 1 A main inclined groove portion 3 composed of a second inclined groove portion 3B extending to the pattern end 1X, and a sub inclined groove portion 4 extending while inclined toward the rear side in the tire rotation direction R from the starting point A toward the outer side in the tire axial direction. It is configured. The second inclined groove portion 3B extends in a curved shape with a predetermined curvature. The sub-inclined groove portion 4 extends from the tread ground contact end TE to a position on the inner side in the tire axial direction so as not to communicate with the tread ground contact TE.

  The groove width of the inclined groove 2 is 9.0 mm to 13.0 mm, the groove depth is 5 mm to 6.5 mm, the groove area ratio of the tread surface 1 is 25% to 30%, and the inclined groove 2 is rotated once at a predetermined pitch. The number of pitches when arranged over a range of 14 pitches to 18 pitches. The same applies to the embodiments shown in FIGS.

  On the tread surface 1, a land portion 5 made of one rib is formed by the left and right inclined grooves 2. The land portion 5 has a plurality of land portion portions 6 that are partitioned by the second inclined groove portion 3B in the tire circumferential direction TC. On the pattern end 1X side of each land portion 6 is provided an overhang portion 7 that projects into the second inclined groove portion 3B adjacent to the land portion 6 on the front side (stepping side) in the tire rotation direction R. . The overhanging portion 7 bulged to the stepped side of the land portion 6 has its surface 7a formed flush with the tread surface 1 and starts overhanging from an area AR where the tire ground contact edge TE is located. Projects to the end 1X. Thus, the groove width of the second inclined groove portion 3B is narrowed by the amount of the protruding portion 7 in the groove portion 3B1 where the protruding portion 7 is provided.

  As a result of earnestly examining the possibility of shortening the running time during competition while ensuring wet performance in pneumatic tires capable of running on public roads mainly intended for use in competitions, the present inventors have found that I found out.

  That is, when driving on a public road, the region between the left and right tire grounding ends TE is grounded to the road surface, and the region on the pattern end 1X side outside the tire grounding end TE in the tire axial direction is not grounded to the road surface. On the other hand, when running on a corner at a high speed during running on a circuit course, the region on the pattern end 1X side on the outer side in the tire axial direction from the tire grounding end TE is also grounded on the road surface. Accordingly, if the region on the pattern end 1X side outside the tire ground contact end TE on the side of the pattern end 1X has no groove, the ground contact area increases accordingly, so that the traction during cornering is improved and the running time is shortened. In addition, it is possible to ensure wet performance when traveling on public roads. However, the rules for racing tires that can run on public roads require that the groove extends to the pattern end of the tread surface.

  Therefore, in the present invention, as described above, the overhanging portion 7 protruding to the stepping side is provided in the adjacent second inclined groove portion 3B on the pattern end 1X side of the land portion 6. When there is a turning center on the left side in FIG. 1 during circuit course cornering, the tread surface region on the pattern end 1X side on the outer side in the tire axial direction from the left tire contact end TE is grounded. The land portion 6 in the region is subjected to an oblique force indicated by the arrow m. By providing the overhang portion 7 in this manner, the land portion 6 having the overhang portion 7 in the arrow m direction is provided. Since the effective contact length becomes longer, the traction property is improved, and as a result, cornering can be performed while maintaining the state in which the accelerator opening is increased for a long time.

  Moreover, since the overhanging portion 7 is provided in the second inclined groove portion 3B on the pattern end 1X side that does not affect the grounding when traveling on a public road, the drainage performance during public road travel is not hindered. Therefore, it is possible to shorten the running time during competition while ensuring wet performance.

  If the overhanging portion 7 is provided on the front side in the tire rotation direction R (the kicking side) of the land portion 6, the effective contact length of the land portion 6 having the overhanging portion 7 in the arrow m direction cannot be increased. That is, if there is the overhanging portion 7 on the kicking side, the overhanging portion 7 escapes to the rear side in the tire rotation direction R due to the force that acts at the time of kicking out, so it does not contribute to traction and the effective contact length is increased as described above. It cannot be made longer.

  In the above-described embodiment, as shown in FIGS. 1 and 2, the area AR where the overhang start portion 7 s where the overhang portion 7 starts to overhang is located in the tire ground contact half width W from the tire ground contact end TE to the outer side in the tire axial direction. It is preferable to be located between a position Q1 of 0.15 times of the tire and a position Q2 of 0.10 times the tire ground contact half width W on the inner side in the tire axial direction from the tire ground contact end TE. When the overhang start portion 7s of the overhang portion 7 is positioned on the inner side in the tire axial direction from the region AR, the drainage performance is hindered due to the decrease in the groove area in the contact region located between the left and right tire contact points TE. When the overhang start portion 7s of the overhang portion 7 is located on the outer side in the tire axial direction from the region AR, the effect of increasing traction during cornering is small, and it is difficult to effectively shorten the travel time. As shown in FIG. 2, the overhang start portion 7s referred to here is a portion from a position P1 where the overhang starts to a position P2 where the overhang amount n of the overhang portion 7 reaches a range (2 mm) described later. It is. When the position P2 is unclear, the position is in contact with a perpendicular drawn in a direction perpendicular to the center line CL.

  The overhang amount (overhang length) n of the overhang portion 7 can be 2 mm or more. When the overhanging amount n of the overhanging portion 7 is less than 2 mm, the effect of increasing traction during cornering is small, and it becomes difficult to effectively shorten the running time. Preferably it is 3 mm or more, so that the effect of increasing the traction during cornering becomes larger, and the running time can be shortened more effectively. More preferably, it should be 5 mm or more.

  The upper limit value of the overhanging amount n of the overhanging portion 7 is from the point of regulation to the overhanging amount where the groove width of the groove portion 3B1 of the second inclined groove portion 3B where the overhanging portion 7 is 3 mm or more. Is good. For example, when the groove width of the second inclined groove portion 3B is 10 mm, the upper limit value of the protruding amount n of the protruding portion 7 is 7 mm, and when the groove width of the second inclined groove portion 3B is 13 mm, the protruding portion 7 The upper limit value of the overhang amount n can be 10 mm. Naturally, in order to further improve the traction performance during cornering, the groove width of the groove portion 3B1 can be made smaller than 3 mm if the wet performance may be sacrificed to some extent. There is no particular limitation as long as the width can be secured.

  Note that, as shown in FIG. 2, the overhang amount n referred to here is a land portion facing the overhang portion 7 in the developed view shown in FIG. 2 when the groove portion 3B1 extends in an arc shape. It is a value measured in a direction perpendicular to the tangent drawn to the edge 6e (on the tread surface) of the portion 6, and is orthogonal to the edge line of the land portion 6 when the groove portion 3B1 extends linearly. Although it is a value measured in the direction, the overhang amount n is calculated as follows for convenience.

  When the groove width GW of the second inclined groove portion 3B is constant, a value obtained by subtracting the groove width GB1 of the groove portion 3B1 measured in the orthogonal direction from the groove width GB is set as an overhang amount n. When the groove width GW of the second inclined groove portion 3B changes (for example, gradually decreases or gradually increases), the groove width at the position Q2 is set as the groove width GW of the second inclined groove portion 3B, and the overhang amount is the same as described above. Let n be determined.

  FIG. 3 shows a tread pattern of another embodiment of the pneumatic tire of the present invention. From the center side to the left and right sides of the center line CL of the tread surface 11 in which the tire rotation direction R is designated in one direction indicated by an arrow. Main inclined grooves 12 that extend to the pattern end 11X of the tread surface 11 beyond the tire ground contact end TE while being inclined toward the rear side in the tire rotation direction R toward the outer side in the tire axial direction are arranged at a predetermined pitch in the tire circumferential direction TC. Has been. These left and right main inclined grooves 12 extend in a curved shape with a predetermined curvature, and are alternately provided in the tire circumferential direction TC while being shifted by a half pitch in the tire circumferential direction TC.

  On the tread surface 11, a land portion 15 made of one rib is formed by the left and right main inclined grooves 12. The land portion 15 has a plurality of land portion portions 16 that are partitioned by the main inclined groove 12 in the tire circumferential direction TC. Each land portion 16 is provided with one sub-inclined groove 13 that extends from the center side toward the rear side in the tire rotational direction R while being inclined toward the outer side in the tire axial direction. Each sub-inclined groove 13 extends to the tire ground contact end TE, but does not extend to the pattern end 11X of the tread surface 11.

  Also in a tire having such a tread pattern, the above-described overhanging portion 7 is adjacent to the land portion 16 on the pattern end 11X side, and adjacent to the land portion 16 on the tire rotation direction R front side (stepping side). By providing so as to project into the inclined groove 12, the same effect as described above can be obtained.

  FIG. 4 shows a tread pattern of still another embodiment of the pneumatic tire of the present invention, in which the tire rotation direction R is set on the left and right sides of the center line CL of the tread surface 21 designated in one direction indicated by an arrow. Left and right inclined grooves 22 that are inclined with respect to the direction are arranged at a predetermined pitch in the tire circumferential direction TC. These left and right inclined grooves 22 are alternately provided in the tire circumferential direction TC while being shifted by a half pitch in the tire circumferential direction TC.

  Each inclined groove 22 extends from the center side starting point A in the vicinity of the center line CL toward the outer side in the tire axial direction R toward the rear side in the tire rotation direction R and beyond the tire contact point TE to the pattern end 21X of the tread surface 21. A main inclined groove portion 23A, a first sub-inclined groove portion 23B extending from the starting point A toward the tire axial direction inward in the tire rotation direction R while being inclined toward the rear side, and a middle inclined portion of the main inclined groove portion 23A in the tire axial direction It is comprised from the 2nd sub inclination groove part 23C extended while inclining in the tire rotation direction R back side toward the outer side. The main inclined groove 23A extends in a curved shape with a predetermined curvature. The first sub inclined groove portion 23B does not extend to the center line CL, and the second sub inclined groove portion 23C does not extend to the tire ground contact end TE.

  On the tread surface 21, a land portion 25 made of one rib is formed by the left and right inclined grooves 22. The land portion 25 has a plurality of land portion portions 26 that are partitioned by the main inclined groove portion 23 </ b> A in the tire circumferential direction TC.

  Even in a tire having such a tread pattern, the above-described overhanging portion 7 is adjacent to the land end portion 25 on the pattern end 21X side and to the land portion portion 26 on the tire rotation direction R front side (stepping side). By providing so as to protrude into the inclined groove 23A, the same effect as described above can be obtained.

  FIG. 5 shows a tread pattern of still another embodiment of the pneumatic tire according to the present invention, in which the tire rotation direction R is set on the left and right sides of the center line CL of the tread surface 31 designated in one direction indicated by an arrow. Left and right inclined grooves 32 extending obliquely with respect to the direction are arranged at a predetermined pitch in the tire circumferential direction TC. These left and right inclined grooves 32 are alternately provided in the tire circumferential direction TC while being shifted by a half pitch in the tire circumferential direction TC.

  Each inclined groove 32 extends from the starting point A on the center side in the vicinity of the center line CL toward the rear side in the tire rotation direction R toward the outer side in the tire axial direction and extends to the pattern end 31X of the tread surface 31 beyond the tire ground contact end TE. The main inclined groove portion 33A and the auxiliary inclined groove portion 33B extending from the starting point A toward the inner side in the tire axial direction while inclining toward the rear side in the tire rotation direction R. The main inclined groove portion 33A extends in a curved shape with a predetermined curvature. The sub-inclined groove portion 33B extending linearly does not extend to the center line CL.

  The tread surface 31 is formed with a land portion 35 formed of one rib by the left and right inclined grooves 32. The land portion 35 has a plurality of land portion portions 36 that are partitioned by the main inclined groove portion 33A in the tire circumferential direction TC. Each land portion 36 is provided with one sub-inclined groove 34 that extends from the center side toward the outer side in the tire axial direction while inclining toward the rear side in the tire rotation direction R. Each sub inclined groove 34 extends to the tire ground contact end TE, but does not extend to the pattern end 31X of the tread surface 31.

  Also in a tire having such a tread pattern, the above-described overhanging portion 7 is adjacent to the land end portion 35 on the pattern end 31X side and adjacent to the land portion portion 36 on the tire rotation direction R front side (stepping side). By providing so as to project into the inclined groove portion 33A, the same effect as described above can be obtained.

  In the present invention, the rubber used for the tread rubber layer constituting the tread surfaces 1, 11, 21, 31 is 50 to 70 in Rüpke JIS hardness (JIS K6255) having a rubber hardness of 60 ° C. and tan δ (60 ° C.). Those of 0, 2 to 0.8, more preferably 0.4 to 0.8 can be preferably used. Tan δ is a value measured using a viscoelastic spectrometer (manufactured by Toyo Seiki Seisakusho) under the conditions of a temperature of 60 ° C., a frequency of 20 Hz, an initial strain of 10%, and a dynamic strain of ± 2%.

  In addition, the groove wall surface s of the overhanging portion 7 is in the range of 10 to 25 ° with respect to the tire radial direction in a cross section cut by a plane orthogonal to the tire rotation axis, such as rigidity of the overhanging portion. To preferred.

  The present invention is not limited to the tread pattern shown in FIGS. 1 to 5 described above. For example, the tread pattern shown in FIG. 6 may be used. The tire rotation direction is designated as one direction, and the tire shaft extends from the center side of the tread surface. Inclined grooves extending to the pattern end of the tread surface beyond the tire ground contact edge while being inclined rearward in the tire rotation direction toward the outer side in the tire direction are arranged at a predetermined pitch in the tire circumferential direction, and a plurality of land is formed by the inclined grooves. Any pneumatic tire may be used as long as the portion is divided in the tire circumferential direction. The inclined groove mentioned here includes a configuration in which the pattern end side does not incline but extends along the tire axial direction or inclines in the opposite direction.

  The present invention is for a passenger car capable of traveling on public roads mainly intended for use in competitions, in which the groove depth of each of the inclined grooves described above is 6 mm or less (5 mm to 6 mm) and the groove area ratio is 25 to 30%. Although it can use preferably for a pneumatic tire, it is not limited to it, The other pneumatic tire for passenger cars etc. may be sufficient.

  In the present invention, the tire ground contact end TE is a position away from the center line CL by the distance of 1/2 of 75% of the JATMA design cross-sectional width outward in the tire axial direction.

  In the tires 1 to 6 of the present invention having the tread pattern shown in FIG. 1 (Examples 1 to 6) and the tire 1 of the present invention having the tire size common to 235 / 45R17 93W, the overhanging portion is on the front side in the tire rotation direction. Instead, comparative tires 1 and 2 (Comparative Examples 1 and 2) provided on the rear side in the tire rotation direction and a conventional tire (conventional example) having no overhanging portion were produced as test tires, respectively.

  In each test tire, the tire ground contact half width W is 97.5 mm, the groove depth of the inclined groove is 5 mm, the groove width is 11 mm, and the number of pitches is 16 pitches. The overhang start portion of the overhang is in the area AR, and the position and overhang amount n are as shown in Table 1.

  Each of these test tires is mounted on a rim having a rim size of 17 × 9 JJ, mounted on a four-wheel drive vehicle (one passenger) with a displacement of 2000 cc, the tire air pressure after form-up is set to 220 kPa, and the following test method is used: When an evaluation test of running time and wet steering stability was performed, the results shown in Table 1 were obtained.

Traveling time The traveling time when a lap of about 2 km on a dry circuit course of 10 laps was measured was measured, and the result was shown as an index with the conventional tire as 100. A larger value indicates a shorter traveling time.

Wet handling stability A feeling test by a test driver was carried out on a wet road test course, and the evaluation result was shown as an index with the conventional tire as 100. The larger this value, the better the wet performance.

  From Table 1, it can be seen that the tire of the present invention can effectively shorten the running time while ensuring the wet performance.

1 is a partial development view of a tread surface showing an embodiment of a pneumatic tire of the present invention. It is a principal part enlarged view of the pneumatic tire of FIG. It is a partial development view of the tread surface showing other embodiments of the pneumatic tire of the present invention. It is the partial expanded view of the tread surface which shows other embodiment of the pneumatic tire of this invention. It is the partial expanded view of the tread surface which shows other embodiment of the pneumatic tire of this invention. It is a partial expanded view of the tread surface of the conventional tire.

Explanation of symbols

1,11,21,31 Tread surface 1X, 11X, 21X, 31X Pattern end 2, 12, 22, 32 Inclined groove 3, 23A, 33A Main inclined groove part 3B Second inclined groove part 3B1 Groove part 5, 15, 25, 35 Land portion 6, 16, 26, 36 Land portion 7 Overhang portion 7a Surface 7s Overhang start portion 12 Main inclined groove CL Center line R Tire rotation direction TC Tire circumferential direction TE Tire contact end n Overhang amount

Claims (6)

The tire rotation direction is designated as one direction, and an inclined groove extending from the center side of the tread surface toward the outer side in the tire axial direction toward the pattern end of the tread surface beyond the tire ground contact edge while tilting backward in the tire rotation direction. In a pneumatic tire that is arranged at a predetermined pitch in the tire circumferential direction, and in which a plurality of land portions are sectioned in the tire circumferential direction by the inclined grooves,
The pneumatic tire which provided the overhang | projection part which protrudes in the inclined groove | channel adjacent to the said land part part by the tire rotation direction front side in the said pattern end side of each land part part.   The pneumatic tire according to claim 1, wherein the projecting portion projects from an area AR where a tire ground contact end is located to the pattern end.   The region AR includes a position Q1 that is 0.15 times the tire ground contact half width W outward from the tire ground contact edge in the tire axial direction and a position Q2 that is 0.10 times the tire ground contact half width W from the tire ground contact edge inward in the tire axial direction. The pneumatic tire according to claim 2 located between.   The pneumatic tire according to claim 1, 2 or 3, wherein the overhang amount of the overhang portion is 2 mm or more.   The pneumatic tire according to any one of claims 1 to 4, wherein a groove width of a groove portion of the inclined groove where the projecting portion is located is 3 mm or more.   The pneumatic tire according to any one of claims 1 to 5, wherein a surface of the protruding portion is flush with a tread surface.

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