JPH09175120A - Pneumatic radial tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To markedly extend a rejection limit of a tire by effectively suppressing uneven wearing of a tread shoulder part. SOLUTION: This tire has a bead core, carcass ply comprising a radial chord layer, belt comprising one or more chord layers and a tread. In both side parts of the tread, a peripheral direction main groove 5 extended in the peripheral direction and many cross direction grooves 6, extended in the tire axial direction between the peripheral direction main groove and a tread end part to open one end part to the peripheral direction main groove and the other end part to a tread end, are provided, an uneven wearing preventing block 7, having a tire axial direction width 50% or more the length of the cross direction groove 6, is provided therein, the tire is rim-assembled in a standard rim by a regular internal pressure, when a regular load is statically loaded, the uneven wearing preventing block 7 is grounded further prevented from coming into contact with a groove side wall of the cross direction groove 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to suppressing uneven wear occurring in a shoulder portion of a pneumatic tire. And in particular, it relates to suppressing uneven wear of the shoulder portion of a radial tire for passenger cars.

[0002]

2. Description of the Related Art In a pneumatic radial tire, uneven wear occurs in the tread portion to some extent even under normal use conditions. However, in radial tires, the shoulder portion is particularly worn, and the tire center portion Even if there is still a ditch, the critical limit is often reached. Further, a tire having lateral grooves often wears unevenly in the tire circumferential direction, which may cause deterioration of tire noise.

Conventionally, in order to solve these problems, the tread rubber has been improved and the crown shape of the tire has been changed to optimize the distribution of the ground contact pressure. Further, JP-A-6-297917 and JP-A-3-15340.
In No. 4, the shoulder convex ridge is provided in the shoulder lug groove to prevent uneven wear of the shoulder. However, these are related to the heavy duty pneumatic tire, and correspond to the force applied in the tire circumferential direction, not the force applied in the width direction.

[0004]

However, in the case of radial tires for passenger cars, the shoulder portion is generally unevenly worn by a widthwise force such as a cornering force, which is different from a heavy load tire. In this situation, the effect cannot be obtained sufficiently. This is particularly noticeable in radial tires for passenger cars having a relatively small crown R. Therefore, an object of the present invention is to solve the problems of the above-mentioned conventional techniques, effectively suppress uneven wear of the shoulder portion of the tread, and significantly extend the tire rejection limit.

[0005]

The present invention adopts the following constitution in order to achieve the above object. That is,
A carcass ply 1 composed of a radial cord layer, which is a bead core provided on a pair of left and right bead parts, a bead core extending from one bead part to the other bead part, and wound around the bead core and moored at the bead part, and a carcass ply. A pneumatic tire comprising a belt 2 composed of one or more cord layers arranged radially outside the crown portion 3 and a tread 4 arranged radially outside the belt, wherein (1) the tread 4 On both sides, a circumferential main groove 5 extending in the circumferential direction, and extending in the tire axial direction between the circumferential main groove and the tread end, one end of which is opened in the circumferential main groove A large number of lateral grooves 6 whose ends are open to the tread end are provided, and (2) the lateral grooves 6 have a tire axial width L1 of 50% or more of the length L0 of the lateral grooves. ,
An uneven wear prevention block 7 is provided, and (3) when the tire is assembled to a standard rim with a normal internal pressure and a normal load is statically applied, the uneven wear prevention block 7 is grounded and the groove of the lateral groove 6 is provided. It is said that it will not touch the side wall.

Further, the width W1 of the uneven wear prevention block 7
When the width is set to be smaller than 40% of the width W0 of the lateral groove 6, it is preferable that the block surface is located on the outer side of the tire radius from the virtual extension line from the adjacent portion. The width of the wear prevention block 7 is 40% of the width W0 of the lateral groove 6.
In the case of the above setting, the block surface is preferably located inside the tire radius from the virtual extension line from the adjacent portion.

During cornering, the shoulder portion of the tire receives a force in the tire width direction and moves relative to the road surface.
As a result, this part is subject to wear and uneven wear occurs. However, if uneven wear prevention block 7 in the lateral groove is provided, this block has less rigidity than block 8 of the main body, and the normal load is static. Since the uneven wear prevention block 7 contacts the ground and does not contact the groove side wall of the lateral groove 6 when it is loaded on the adjacent block 8, it deforms before the main body block 8 and also bears a load to some extent, so It works to suppress movement near the edges. That is, it plays a cushioning role to reduce the relative movement of the block 8 with respect to the road surface. Therefore, the property of the uneven wear prevention block is that it is easily deformed and bears a load. It must also be taken into consideration that if the proportion of the lateral groove is too large, the traction performance and the wet performance are also adversely affected.

In the present invention, the lateral groove 6 has a tire axial width L1 of 50% or more of the length L0 of the lateral groove,
When the regular load is statically applied, the uneven wear prevention block 7 comes into contact with the ground, so that it has a sufficient load bearing capacity and does not come into contact with the side wall of the lateral groove 6, so that it can be deformed prior to the block 8. It is like this. L1 / L here
The preferable range of 0 is 60 to 85%.

Further, in the present invention, when the width W1 of the uneven wear prevention block 7 is set to be smaller than 40% of the width W0 of the lateral groove 6, the block surface has a tire radius from an imaginary extension line from its adjacent portion. Positioning on the outside is preferable because the load of the load increases.

Further, in the present invention, when the width W1 of the uneven wear prevention block 7 is set to be 40% or more of the width W0 of the lateral groove 6, the block surface has a tire radius from an imaginary extension line from its adjacent portion. Positioning inside is preferable because it facilitates deformation during cornering of the uneven wear prevention block,
Wet performance will not deteriorate. Further, the block surface can exert its effect even at the same position as the virtual extension line from the adjacent portion.

Here, the range of W1 / W0 is 3 in consideration of the effect of preventing uneven wear and the wet performance / traction performance.
0-60% is preferable. When it is about 90%, the traction performance is deteriorated and the uneven wear preventing block comes into contact with the lateral groove side wall at the time of contact with the ground and is less likely to be deformed, so that the uneven wear preventing effect is lowered.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a partial front view of the tread pattern showing the embodiment of the pneumatic tire of the present invention, and the tire size is 185 / 70R14. In the present embodiment, as shown in the figure, uneven wear preventing blocks 7 are provided in the lateral grooves on both sides of the tire. FIG. 3 is a cross-sectional view taken along the line AA ′ of FIG. 2. (a) is an example in which the uneven wear prevention block is located inside the tire radius from a virtual extension line from an adjacent portion,
(B) has shown the example located in a tire radius outer side.

Next, in order to confirm the effect of the present invention, Table 1
Also, five types of tires having a tire size of 185 / 70R14 according to FIG. 1 were prototyped. The structure is a general one carcass ply and two steel belt structures, which are exactly the same except for the presence or absence of the uneven wear prevention block and its shape. The test shows that the internal pressure is 1.9kgf / on the rim of 5 1/2 J.
Built in cm ^2, and under the following conditions at a flat belt abrasion tester.・ Road surface: Safety walk ・ Temperature: 30 ° C ・ Load: 40kgf ・ Slip angle: 0.5 ° ・ Load braking force: 50kgf ・ Speed: 50km / h ・ Distance traveled: 200km (equivalent to about 10,000km actual travel)

[0014]

[Table 1]

[0015]

As shown by the above results, the tire of the present invention can effectively suppress uneven wear of the tread shoulder portion.

[Brief description of the drawings]

FIG. 1 is a partial sectional view in the tire width direction of a tread pattern showing an example of the present invention.

FIG. 2 is a partial front view of a tread pattern showing another embodiment of the present invention.

3 is a cross-sectional view taken along the line A-A ′ in FIG.

[Explanation of symbols]

 1 Carcass Ply 2 Belt 3 Crown 4 Tread 5 Circumferential main groove 6 Lateral groove 7 Uneven wear block 8 Block E Tire equatorial line (pattern center) L0 Lateral groove length L1 Uneven wear block length W0 Width of lateral groove W1 Width of uneven wear prevention block H0 Height of lateral groove H1 Height of uneven wear prevention block

Claims (3)

[Claims] 1. A bead core provided on a pair of left and right bead portions, and extending from one bead portion to the other bead portion,
A carcass ply wound around the bead core and anchored to the bead portion, the carcass ply consisting of a radial cord layer, a belt formed of one or more cord layers arranged radially outside the crown portion of the carcass ply, and a belt of the belt. In a pneumatic tire having a tread arranged radially outward, (1) on both sides of the tread, a circumferential main groove extending in the circumferential direction, and between the circumferential main groove and the tread end portion. A plurality of lateral grooves extending in the tire axial direction, one end of which is opened in the circumferential main groove and the other end of which is opened in the tread end, and (2) in the lateral groove, An uneven wear prevention block having a width in the tire axial direction of 50% or more of the length of the lateral groove is provided, and (3) the tire is assembled to a standard rim at a regular internal pressure, and a regular load is statically applied. Sometimes, the uneven wear prevention block A pneumatic radial tire click is characterized in that it does not contact the groove sidewalls of the grounded and said lateral groove. 2. The width of the uneven wear prevention block is smaller than 40% of the width of the lateral groove, and the surface of the block is located outside the imaginary extension line from its adjacent portion to the outside of the tire radius. The pneumatic radial tire according to claim 1. 3. A width of the uneven wear prevention block is 40% or more of a width of the lateral groove, and a surface of the block is located inside a tire radius from an imaginary extension line from its adjacent portion. The pneumatic radial tire according to claim 1.