JPH10226207A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve remarkably abrasion resistance by making a siping exhibit its original function fully. SOLUTION: A lap grooves 2, 3 are provided to the tread part 1, each curved siping 7, 8, of which one end opens at each side edge and another end finishes in the land part, is formed in the land part 4 located closest to the tread center C-C, is formed shifting a phase in the circumferential direction. A tangent drawn to each curved siping 7, 8 is orthogonalized the land part center line and crossed the land part side edge at an acute angle. Notch parts 11, 12 are provided in the corner part of the acute angle side land part 9, 10 which are sectioned by the lap groove 2 and the curved sipings 7, 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire having a land portion, for example, a rib, which is located closest to a tread center, a sipe having one end opened in a circumferential groove, and particularly to a pattern structure. It is intended to effectively improve wear resistance while ensuring performance.

[0002]

2. Description of the Related Art For the purpose of improving the wet performance and the contact property of a tire, it has been conventional to provide a sipe on a rib located close to a tread center. , FIG.

FIG. 4A shows a center rib CR, for example.
In FIG. 4, a plurality of sipes S extending continuously from one side edge to the other edge are formed in an oblique straight line.
(B) shows the center rib CR, each oblique straight sipe S1, S2 having one end opened at each side edge and the other end ending in the rib, at the same circumferential position,
4 are formed in the same direction.
(C), each of the oblique linear sipes S3, S4, each having one end opened at each side end of the center rib CR and the other end ending in the rib, are inclined in opposite directions to each other, and are circumferentially It is formed out of phase.

[0004]

However, FIG. 4 (a)
When each sipe S is opened on both side edges of the center rib CR as shown in FIG.
As a result, the rigidity of each subdivided land portion is reduced, so that the abrasion resistance of the entire center rib is reduced.
As shown in (b) and (c), the sipes S1, S2, S3, S open at one end only at the side edges of the center rib CR.
In the case where the ribs 4 are provided, as shown in the example of one sipe S4 in FIG. 5A, when a circumferential force such as a braking force or a traction force is input to the rib CR, for example, as shown by a broken line in the drawing. Each sipe S4 is particularly greatly expanded and deformed at the opening to the side edge of the rib, and there is a problem that the abrasion resistance at the large deformation portion is particularly low.

[0005] Here, as shown in FIG. 4 (b), the oblique linear sipes S1 and S2 are formed so as to prevent a reduction in rigidity of the entire center rib and to secure a sufficient sipe length. For the purpose, when the phase is shifted in the circumferential direction, as shown in FIG. 5 (b), the circumferential force acting on the rib CR causes the ribs generated from the inner ends of the ribs of the sipes S1 and S2. Crack tr which progresses in the direction perpendicular to the direction in which the ribs CR extend tends to continue to the sipes S1 and S2 adjacent in the width direction of the rib CR. As a result, the ribs are chipped and the rigidity of the land portion is reduced. This leads to early progress of wear and the like.

SUMMARY OF THE INVENTION The present invention has been made as a result of studying to solve such problems of the prior art, and the purpose of the present invention is to provide a sipe with its full function. It is still another object of the present invention to provide a pneumatic tire capable of greatly improving abrasion resistance without the risk of occurrence of chipping of a rib or the like.

[0007]

A pneumatic tire according to the present invention is provided with four or more circumferential grooves extending continuously in a linear or zigzag manner in a circumferential direction on a tread tread portion. Among the land sections defined by the above, one end is opened at each side edge of the land section, and the other end is in the land section, for example, the center in the width direction of the land section. Each curved sipe ending in the part is formed in the circumferential direction, for example, shifted in phase by a half pitch of their arrangement pitch, and the tangent drawn on each curved sipe is
At right angles to the land center line, cross the land side edge at an acute angle, and make a corner of the acute side land part defined by the circumferential groove and the curved sipe, for example, at a right angle to the land surface. A notch defined by a wall surface or an inclined surface that gradually reduces the height of the land portion toward the tip is provided.

In the pneumatic tire configured as described above, each sipe extends in a curved shape, and a tangent drawn on each curved sipe is orthogonal to the land center line, and By crossing the side edges at an acute angle, the amount of deformation of each sipe on the land surface, for example, in the expanding direction, when external forces in the braking and driving directions act on the land, The opening to the side edge of the part and its vicinity can be made sufficiently small, while the part near the land center line can be made sufficiently large, whereby
Since the amount of deformation of each sipe is almost uniform over its entire length, the wear state is effectively uniformized from the center of the land to the side edges, and the wear resistance and uneven wear resistance are advantageously improved. Can be.

In addition, since the tangents drawn on each curved sipe are perpendicular to the land center line, the curved sipe can be used to prevent the rigidity of the entire center rib from lowering. For the purpose of securing a large sipe length, the phase is shifted in the circumferential direction, and the cracks generated from the terminal position inside the land of each sipe may progress in the width direction of the land. In addition, it is possible to sufficiently eliminate the possibility that the crack may reach another sipe adjacent in the width direction of the land portion, and as a result, the sipe may be communicated with each other, in addition to the occurrence of chipping in the land portion. By
The risk of premature wear of the land portion can be eliminated.

Further, in this tire, a notch is provided at a corner of an acute-side land portion defined by a circumferential groove and a curved sipe, and high rigidity is secured in the remaining land portion. The corners serve as nuclei for uneven wear, and the uneven wear can be effectively prevented from progressing therefrom.

By the way, in this tire, the curved sipes described above are provided on the land portion located closest to the tread center, so that the wear resistance and the crack resistance can be sufficiently secured. Excellent driving force and braking force against a wet road surface can be exerted on the land where the contact pressure within the contact surface is highest. Further, here, by providing four or more circumferential grooves on the tread tread portion, excellent drainage performance on wet road surfaces is ensured.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a development view of a tread portion showing one embodiment of the present invention.
Indicates a tread tread portion, and reference numerals 2 and 3 respectively denote two circumferential grooves arranged at intervals of a tread center CC.

Here, a total of four circumferential grooves 2 and 3 extending linearly and continuously in the circumferential direction and the respective side edges of the tread tread portion 1 also form a linear shape in the circumferential direction. While dividing five consecutive ring land parts 4,5,6,
The annular land portion 4, which is located closest to the tread center CC, the land center line is opened in the land portion 4 located on the tread center CC, and one end is opened at each side edge thereof. Then, the respective curved sipes 7, 8 whose other ends end at the land center position are formed with their phases shifted from each other in the circumferential direction.

As shown in the figure, of these curved sipes 7 and 8, the sipe 7 is curved in a direction protruding downward in the figure, and the sipe 8 is curved in a direction protruding upward. I do. Each of the curved sipes 7 and 8 can be curved in the same direction either upward or downward, and can be curved in an arc shape.

Further, in this case, the tangent drawn on each curved sipe is perpendicular to the tread center CC, and crosses the land side edge at an acute angle θ. , 8 on the acute-angled land portion 9, 1
For example, notches 11 and 12 defined by wall surfaces that are substantially perpendicular to the surface of the land portion 4 are provided at the 0 corners.

The other land portions 5 and 6 of the tire have respective sipe 13 and 13 having an extended form as if the respective curved sipes 7 and 8 described above were interconnected.
14, each end of the sipe 13 extending across the land portion 5 is opened in each of the circumferential grooves 2 and 3, and one end of the sipe 13 formed in the land portion 6 is formed in the circumferential groove 3. The other end of the opening sipe 14 terminates in its land.

Further, in the illustrated tire, so-called braking control ribs 15 functioning as uneven wear sacrifice portions are provided in the respective circumferential grooves 3 located on the outermost side of the tread tread portion 1. As disclosed in, for example, Japanese Patent Application Laid-Open No. 2-169305, the braking control rib 15 has a step height lower than that of each of the land portions 5 and 6 so as to support a load. Sliding contact with the road surface in the area where the treads are in contact with each other, to replace uneven wear that would occur on the land portions 5 and 6, and the braking control ribs 15 in this case have a plurality of ribs crossing the width direction thereof. With a sipe.

When the pneumatic tire constructed as described above is subjected to load rolling, braking and driving forces are applied to the annular land portion 4, and the respective sipes 7, 8.
The expansion deformation on the land surface is performed as shown by a broken line in the enlarged view of the main part of FIG. 2, and the amount of deformation at the opening end to the circumferential groove 2 and the vicinity thereof is determined by the terminal position in the land. And the deformation amount in the vicinity thereof is equal to or slightly larger than the deformation amount, and the difference between the two deformation amounts is much smaller than that in the case shown in FIG. The wear conditions from the central part of 4 to its respective side edges are sufficiently homogenized, so that each of the wear resistance and the uneven wear resistance is advantageously improved.

Each of the curved sipes 7 and 8 has a tangent drawn on the tread center C-.
C, the cracks may be generated from the terminal positions of the sipe 7 and 8 in the land portion, and the crack may be formed in another sipe adjacent in the land width direction. 7 and 8 can be sufficiently removed, and further, notches provided at the corners of the acute-side land portions 9 and 10 defined by the respective circumferential grooves 2 and the curved sipes 7 and 8 By imparting the required rigidity to the remaining land portions 9 and 10 by the portions 11 and 12, it is possible to sufficiently prevent uneven wear of the land portions 9 and 10.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the invention tire having the tread pattern shown in FIG. 1 will be described below with reference to abrasion resistance and wet performance. Tire size 295 / 75R2
The wear resistance was evaluated by measuring the wear volume after running 100,000 km under the conditions that the filling internal pressure was 8.0 kg / cm ² , and the applied load per tire was 2700 kg. , And wet performance,
The evaluation was performed by applying a sudden brake on an asphalt pavement having a water depth of 1.5 mm and measuring a braking distance from an hourly speed of 60 km / h to a stop.

The results are shown in Table 1. The index values in the table are based on the conventional tire having the tread pattern shown in FIG. 3, and the larger the index value, the better the result.

[Table 1] According to Table 1, it is clear that the inventive tire can significantly improve the wear resistance while securing sufficient wet performance.

[0022]

As described above, according to the present invention, excellent wet performance is ensured based on the action of each curved sipe provided on the land closest to the tread center, and the wear resistance is still improved. Can be improved.

[Brief description of the drawings]

FIG. 1 is a development view of a tread portion showing one embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of FIG. 1 showing a deformed state of the sipe.

FIG. 3 is a development view of a tread portion of a conventional tire.

FIG. 4 is a diagram showing a form of a conventional sipe.

FIG. 5 is a diagram showing a deformed state of a sipe and a mode of progress of a crack.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tread tread portion 2, 3 Peripheral groove 4, 5, 6 Annular land portion 7, 8 Curved sipe 9, 10, Acute angle side land portion 11, 12, Notch portion 13, 14, Sipe 15 Breaking control rib CC Tread center

Claims (1)

[Claims] 1. A tread portion having four or more circumferential grooves continuous in a circumferential direction on a tread tread portion, and a land portion defined by those circumferential grooves and located closest to a tread center, and Each curved sipe, one end of which is open at the side edge and the other end of which ends in the land, is formed with a phase shift in the circumferential direction, and the tangent drawn on each curved sipe is taken as the land center line. A pneumatic tire which is orthogonal to and intersects a land side edge at an acute angle, and has a notch at a corner of an acute angle land part defined by a circumferential groove and a curved sipe.