JPH0338410A - Eccentric wear controlled pneumatic tire - Google Patents

Abstract

PURPOSE:To reduce eccentric wear and to reduce grounding noises by extending a lateral groove at a tread end in the circumferential direction of a ground profile, and shallowly inclining the block end portion near by the lateral groove parting therefrom toward the lateral groove and a radial directional inside. CONSTITUTION:Under the conditions of pressure within prescribed pressure and loading, kick-out portions 29 parallel to ground shaped tangential lines are formed on each block 28 at left half except for each central block range and also step-in portions 31 are formed thereon. Likewise, at right half, the kick-out portions 29 and the step-in portions 31 are formed reversely. Chamfer portions 32 inclined to the bottom portion 30A of a lateral groove 30 are formed at the respective kick-out portions 29, and the maximum depth H thereof is set 1-5mm and the circumferential length L thereof is set within 3-30% of the block 28. According to this construction, eccentric wear can be prevented and also grounding noises can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a pneumatic tire with controlled uneven wear, and more particularly to a pneumatic tire with controlled uneven wear that has a block-shaped tread pattern.

[Conventional technology]

Conventionally, in pneumatic tires, in order to improve driving performance and braking performance, a plurality of circumferential grooves extending along the circumferential direction of the tire and a plurality of circumferential grooves extending approximately in the width direction of the tire at an angle with respect to the equatorial plane of the tire are used. Tread patterns are known that are constructed of base-shaped blocks defined by a large number of lateral grooves, or blocks shaped like arranged bases.

However, when this pneumatic tire touches the ground, as shown in FIG. In some cases, θ and the angle β of the tangent S to the ground contact shape with respect to the circumferential direction of the tire are substantially equal.

In this case, when the block passes through the ground contact surface during running, the circumferential shearing force of the kicking part 52A of the block 52 becomes excessive compared to that of the stepping part 52B, and the kicking part 52A precedes the stepping part 52B. and wear out.

Therefore, uneven wear (heel-ant wear) occurs on the block 52 along the circumferential direction of the tire. Furthermore, when the vehicle turns the steering wheel to the left or right while driving, the difference in ground contact pressure between the half areas in the width direction of the tread portion 50 causes a difference in ground contact sound, which causes discomfort to the occupant. Here, the treading part of the block refers to the circumferential end of each block that enters the ground contact surface before the block passes the ground contact surface and leaves the ground contact surface before the block passes through the ground contact surface during running, and The kick-off portion refers to the circumferential end of the block that enters the ground contact surface later and leaves the contact surface later.

[Problems solved by the invention]

The present invention takes the above facts into consideration, and provides a pneumatic tire with controlled uneven wear that can reduce uneven wear of blocks formed in the tread portion and eliminate discomfort caused by differences in ground contact sound during steering wheel operation. is the purpose.

[Means and actions to solve the problem]

The present invention includes a toroidal radial carcass, a non-stretchable belt layer and a tread sequentially arranged on the radially outer side of the crown portion of the carcass, and the tread has a plurality of circumferential grooves arranged at predetermined intervals in the axial direction. , horizontal grooves extending between the wave grooves and the tread edges and arranged substantially parallel to each other at predetermined intervals with respect to the circumferential direction, and blocks defined by these grooves and the tread edges to prevent uneven wear. In the controlled pneumatic tire, at least one of the left and right lateral grooves extending at the tread end extends generally in the circumferential direction and is defined by these lateral grooves on a ground contact profile that occurs under specified internal pressure and load conditions when the tire is assembled on a rim. When the block passes through the ground contact surface during running, the end of the block adjacent to the lateral groove that leaves behind the ground contact profile is provided with a ground contact surface that is shallowly inclined radially inward toward the lateral groove. It is a feature.

Therefore, in the pneumatic tire with controlled uneven wear of the present invention, at least one of the left and right lateral grooves extending at the tread edge extends generally in the circumferential direction along the ground contact contour that occurs under specified internal pressure and load conditions when the tire is assembled on a rim. , when the blocks defined by these lateral grooves pass through the ground contact surface during running, the end of the block near the lateral grooves, which leaves behind the ground contour, slopes shallowly radially inward toward the lateral grooves. equipped with a ground surface. Therefore, the shearing force in this portion can be reduced. Therefore, it is possible to reduce the wear of the kicking part of the block during load transfer, and to eliminate the discomfort caused by the difference in ground noise when operating the handle.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

As shown in FIG. 3, in the pneumatic tire 10 with controlled uneven wear, both ends in the longitudinal direction of the radial carcass 12 extending in a toroidal shape are wound around a bead core 14 formed in a ring shape around the tire rotation axis. The radial carcass 12 is covered with an air-impermeable inner liner rubber layer I6.

The portion of this rubber layer 16 that comes into contact with the road surface is a thick tread portion 18 . The tread portion 18 has shoulders 81B20 near both ends in the tire width direction where the radius of curvature becomes small, and the crown portion 21 is located between the shoulder portions 20, and the tread portion occupies these positions.

Further, a non-extensible belt layer 22 made of a plurality of cord plies, which is known per se, is disposed between the tread portion 18 and the radial carcass 12, and reinforces the crown portion 21.

As shown in FIG. 1, in the tread pattern of the tread portion t8, in this embodiment, there are four circumferential grooves 2 at predetermined intervals in the tire width direction (left-right direction in FIG. 1).
4 are arranged along the circumferential direction of the tire (vertical direction in FIG. 1). The circumferential grooves 24 at both ends in the tire width direction are
The inner end 28A in the tire width direction of the blocks 28 constituting the block row 26 at both ends in the tire width direction of the ground contact area C (corresponding to the actual tread width) at the normal internal pressure and load of the trend portion 18 is divided. There is.

Further, in the tread portion 18, lateral grooves 30 inclined with respect to the equatorial plane B of the tire are arranged at approximately equal intervals in the circumferential direction of the tire, and partition both ends of the blocks 28 along the circumferential direction of the tire. ing.

When the pneumatic tire 10 with controlled uneven wear rotates upward in FIG. 1 (in the direction of arrow R), the first
The upper side in FIG. 1 of each block 28 in the left half area E in the figure, except for the blocks in the central block row, becomes a kick-out portion 29 that is substantially parallel to the tangent to the grounding shape. Further, the lower side of each block 28 in FIG.
becomes.

On the other hand, when the pneumatic tire IO with controlled uneven wear rotates in the direction of arrow R (lower side c in FIG. 1), each block 2
The lower side of each block 28 in the right half area in FIG. 1 of FIG. 8 of FIG.
The width is about 1/3 of the circumferential length of the block from the adjacent lateral groove toward the circumferential center of the block. Further, the upper side of each block 28 in FIG. 1 becomes a stepped-in portion 31 (width approximately ⅓ of the circumferential length of the block from the adjacent lateral groove toward the circumferential center of the block).

As shown in FIG. 2, the kicking part 2 of the block 28
9 is formed with a chamfered portion 32 that is inclined toward the bottom portion 30A of the lateral groove 30. The maximum depth H of this chamfered portion 32 is 2 mm.

Further, the length L of the chamfered portion 32 in the circumferential direction of the tire is 5 mm.
The length W in the circumferential direction of the tire of block 28 is
is said to be 30 mm.

Next, the operation of this embodiment will be explained.

In the pneumatic tire lO with controlled uneven wear of this example,
A chamfered portion 32 is formed in the kick-out portion 29 along the lateral groove 30 of the block 28.

Therefore, when the direction of the lateral groove 30 and the direction of the tangent to the grounding shape are substantially parallel, the shearing force of the kick-out portion 29 can be prevented from increasing.

Therefore, it is possible to reduce the wear of the kick-out portion 29 of the block 28 during load transfer, and also to reduce the difference in ground noise generated from the contact surface between the block 28 and the road surface during steering wheel operation, and to reduce the amount of noise caused by the difference in ground contact noise. can eliminate the discomfort of

Note that the length L of the chamfered portion 32 in the circumferential direction of the tire may be constant, and the length L of the chamfered portion 32 in the tire circumferential direction may be constant.
The chamfered portion 34 formed at 8 may be changed as appropriate along the width direction of the tire.

(Experimental Example 1) Each pneumatic tire (tire size 205/65R15) equipped with a tread portion without a chamfered portion according to the embodiment of the present invention (Fig. 1) and the conventional technology was After running 20,000 km, the difference between the height of the stepping side of the block (height M in Figure 2) and the height of the kicking side (height N in Figure 2) (height H in Figure 2), Table 1 shows the results of observing the so-called heat-and-wear index.

Table 1 Note that the heat-and-wear index of the tire of the present invention in Table 1 is 10% higher than the heat-and-wear index of the conventional tire.
It is shown as an index set to 0.

As a result, it was confirmed that the heat ant wear index of the pneumatic tire with controlled uneven wear of this example was 50% of the wear level difference of the conventional pneumatic tire.

(Experimental Example 2) New pneumatic tires (tire size 205/65R15) equipped with tread parts without chamfered parts according to the embodiment of the present invention (Fig. 1) and those of the prior art were used to travel 40 km on a ship route. Table 1 shows the results of observing the noise level [overall dB (A)) when the vehicle was traveling at a speed of 100 m/h and turning with a turning radius of 40 m.

Note that the noise level of the tire of the present invention in Table 1 is an index with the noise level of the tire of the present invention when traveling straight as 100.

The noise level of the conventional tire is an index with the noise level of the conventional tire when traveling straight as 100.

As a result, the noise level of the pneumatic tire of the present invention is
Compared to the noise level of conventional pneumatic tires, the difference in noise depending on the turning direction was small, and it was found that the tire hardly caused any discomfort to the occupants.

These experimental results have revealed that the pneumatic tire with controlled uneven wear of the present invention described above is particularly excellent.

〔Effect of the invention〕

Since the present invention has the above-described structure, it has the excellent effect of reducing uneven wear of the blocks formed in the tread portion and eliminating discomfort caused by differences in ground noise when operating the steering wheel.

[Brief explanation of drawings]

Fig. 1 is a plan view showing a tread pattern of a pneumatic tire with controlled uneven wear according to an embodiment of the present invention, Fig. 2 is a sectional view taken along the line ■-■ in Fig. 1, and Fig. 3 is an embodiment of the present invention. A cross-sectional view cut along the tire width direction and partially omitted with hatching, showing a pneumatic tire with controlled uneven wear according to an example, No. 4
The figure is a plan view showing a ground contact pattern of a pneumatic tire according to the prior art. 10... Pneumatic tire with controlled uneven wear, 12...
- Carcass, 18... Tread portion, 22... Belt layer, 24... Circumferential groove, 28... Block, 29... Kicking part, 30... Lateral groove, 32.34 ... Chamfered part.

Claims (3)

[Claims] (1) a toroidal radial carcass, a non-stretchable belt layer sequentially disposed radially outward of the crown portion of the carcass, and a plurality of circumferential grooves including treads, the treads being disposed at predetermined intervals in the axial direction; A control device for controlling uneven wear, comprising horizontal grooves extending between the grooves and the tread end and arranged substantially parallel to each other at predetermined intervals in the circumferential direction, and a block partitioned by these grooves and the tread end. In the pneumatic tire, at least one of the left and right lateral grooves extending at the tread end extends generally in the circumferential direction of the ground contact profile that occurs under specified internal pressure and load conditions when the tire is assembled on a rim, and is divided into these lateral grooves. The block is characterized in that when the block passes through the ground contact surface during running, the block end adjacent to the lateral groove that leaves behind the ground contact profile is provided with a ground contact surface that is shallowly inclined radially inward toward the lateral groove. Pneumatic tires with controlled uneven wear. (2) The maximum depth of the inclined ground contact surface is 1 mm to 5 mm lower than the ground contact surface, and the length of the inclined ground contact surface in the circumferential direction of the tire is in the range of 3% to 30% of the block. A pneumatic tire with controlled uneven wear according to claim (1). (3) The inclined ground contact surface is formed in the entire area of the block in the tire width direction.Claim (1)
A pneumatic tire with controlled uneven wear according to the description or claim (2).