JPH061114A - Automotive tire - Google Patents

Abstract

PURPOSE:To prevent the deterioration of wet skid performance and reduce tire noise even when a tread wears by forming the groove pattern of outer side in the radial direction into a rib pattern and at least a part of the groove pattern in the inner side in the radial direction into a block pattern, in the using area of the tread. CONSTITUTION:A precure tread 4 is stuck with an adhesive agent to the crown section of a base tire 2 through a cushion rubber 3, The groove pattern of this tread 4 is formed into a rib pattern on the outer side in the radial direction and a block pattern of on inner side in the radial direction, and the tread is made in such a way that when the tread wears by 30-40% of total depth of the groove, the rib pattern turns into the block pattern. This rib pattern comprises the ground contact sections of the outer side in the radial direction, which are opposed to each other with a tread groove 20 between them and connected to each other by a plurality of connection sections 40, and the thickness (t) of these connection sections 40 is set at 10 to 15% of the total depth D of the grooves 25 which will become lateral grooves after wearing. Therefore, even if the tread 4 wears, this tire can be used in all seasons in districts where snow lies in winter without deteriorating wet skid performance and increasing noise.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention provides a unique tread groove pattern which does not deteriorate wet skid performance even if the tread wears, has a small tire noise, and can be used throughout the winter season in snowy areas. The present invention relates to an automobile tire.

[0002]

2. Description of the Related Art As a tread groove pattern for an automobile tire, a rib pattern as shown in FIG. 6 is generally used, and in an area having snow in winter, a block pattern as shown in FIG. 7 is used in winter. Is used for.

That is, in FIG. 6, the tread groove 100 is shown.
Is along the tire circumferential direction (vertical direction in the figure), and is indicated by (1) in FIG.
Is the groove pattern of the ground surface in the unused state, (2) is the groove pattern of the ground surface when the tread is 25% worn,
(3) is a groove pattern of the ground contact surface when the tread is 50% worn, (4) is a groove pattern of the ground surface when the tread is 75% worn, and (5) is tread wear showing the wear limit of the tread. The groove pattern of the ground plane in the state where the indicator (TWI) appears is shown respectively.

In FIG. 7, the tread groove is composed of a groove 110 along the tire circumferential direction (vertical direction in the figure) and a groove 111 along the rotational axis direction (horizontal direction in the figure). Is a groove pattern of the ground surface in an unused state, (2) is a groove pattern of the ground surface when the tread is worn by 20%, (3) is a groove pattern of the ground surface when the tread is worn by 30%, (4) is a groove pattern of the ground contact surface when the tread is 50% worn, (5) is a groove pattern of the ground contact surface when the tread is 70% worn, and (6) is T.I. W.
I. 3 shows a groove pattern on the ground plane in a state where the mark appears. In this case, the groove pattern on the ground contact surface changed to a rib pattern with the tread worn by 70%.

[0005]

The following Table 1 shows the relationship between the depth of the tread groove and the braking distance. The tire size is 10. When running at 60 km / h according to the Japan Automobile Tire Manufacturers Association (JATMA) standard. The result of the test in 00R20 14PR is shown. The braking distance is expressed as an index with the value in the unused state without tread wear being 100, and the smaller the index, the longer the braking distance.

[0006]

[Table 1]

It can be seen from Table 1 above that the wet skid performance deteriorates as the tread wear advances and the tread groove becomes shallower. Further, the width of the tread groove is generally narrowed as the tread wear progresses, and the ground contact pressure is increased to reduce the wear. Therefore, as the tread wear progresses, the wet skid performance deteriorates significantly.

Therefore, it is considered that the groove pattern of the tread is a block pattern to maintain sufficient wet skid performance even when the tread is worn. However, since the tread groove of the block pattern is mainly intended for use on snow or on a bad road, there is a problem that noise is increased when used on a paved road without snow.

[0009] In areas where there is snow in winter,
BACKGROUND ART Tires having rib pattern tread grooves are mounted on automobiles in the summer, and tires having block pattern tread grooves are mounted on the automobile in winter. However, changing tires depending on the season is troublesome, and it is necessary to hold many rim wheels. Further, if the rim wheel is shared by tires having different tread patterns, it is very troublesome to attach and detach the tire to and from the rim.

An object of the present invention is to provide an automobile tire having a tread pattern which can solve the above-mentioned problems of the prior art.

[0011]

The feature of the present invention is that the groove pattern on the radially outer side in the use area of the tread is a rib pattern, and at least a part of the groove pattern on the radially inner side is formed. It is a block pattern.

The tread is a precure tread attached to a base tire, and radial outer side ground contact portions facing each other across a rib pattern tread groove are located in the tread groove. It is preferable that they are connected by a connecting portion.

[0013]

The groove pattern of the ground contact surface in the automobile tire of the present invention is a rib pattern when the tread is not worn, and becomes a block pattern when the tread is worn. Therefore, while the groove pattern on the ground contact surface is the rib pattern, the tread groove is deep, so that wet skid performance is excellent and tire noise is small.

Even if the tread groove becomes shallow due to the progress of wear of the tread, the groove pattern on the ground contact surface becomes a block pattern so that the wet skid performance is not deteriorated and the tread groove is shallow. As a result, the noise does not increase even with the block pattern. That is, the following Table 2 shows the noise level with respect to the depth of the tread groove, which is expressed as an index with the noise in the tread groove of the block pattern having no tread wear as 100. The smaller the index, the smaller the noise. Indicates. The noise level was measured on the drum by setting the running speed to 80 km / h and tire size: 10.0.
0R20 14PR, sound pressure was measured with a sound level meter that displays decibels with A characteristics.

[0015]

[Table 2]

From Table 2 above, if the groove depth is the same, the block pattern is noisier than the rib pattern.
It can be seen that even with the block pattern, the noise decreases as the groove depth decreases. Therefore, it can be confirmed that the noise when the block pattern appears as the groove pattern of the grounding surface is not so large by forming the rib pattern on the radially outer side of the tread and the tread pattern on the radially inner side.

The change of the groove pattern from the rib pattern to the block pattern is preferably performed at a stage where the tread wear progresses by 30% to 40% of the total groove depth.
The tread is not usually used until 100% of the total groove depth is worn, and generally the usage area is about 90% of the total groove depth, and when the groove becomes shallow, the wet skid performance can be reliably ensured. This is to prevent the deterioration. Further, generally, tire standards include a shallow groove level and a deep groove level, but it is preferable to set the deep groove level suitable for long-term use.

In areas with snow in winter,
By mounting the tire having the structure of the present invention at the time after the thaw and changing the tread groove of the ground contact surface into a block pattern in the winter, it becomes possible to use the tire throughout the season without replacing the tire. .

Further, by using the tread as a pre-cure tread to be attached to a base tire, a groove pattern on the outer side in the radial direction is a rib pattern, and a groove pattern on the inner side in the radial direction is a block pattern. It can be easily manufactured without using a special mold. That is, if the tread having the structure of the present invention is to be vulcanized and molded in the molding die together with the carcass assembly and the sidewalls, a block pattern on the radially inner side is obtained by using a normal molding die. The groove portion of the tread groove along the tire rotation axis direction cannot be formed. If it is attempted to form such a groove portion along the tire rotation axis direction on the radially inner side of the tread, for example, the mold does not protrude into the mold while the mold is open, and the mold is closed after the mold is closed. A special mold with a retractable core that projects into it must be used. On the other hand, in the case of the precure tread, since the belt-shaped tread may be attached to the base tire after vulcanization molding, the structure of the molding die does not become complicated due to the molding.

In the case where the tread is a pre-cure tread, the grounding portions are connected to each other by connecting the radially outer grounding portions facing each other across the tread groove having the rib pattern with the connecting portion. It can be prevented from separating. Further, the connecting portion suppresses the movement of the ground contact portion during traveling, and uneven wear of the tread can be prevented.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

The radial tire 1 according to the first embodiment shown in FIG. 2 is constructed by attaching a precure tread 4 to the crown portion of a base tire 2 via a cushion rubber 3 with an adhesive. The base tire 2 covers a carcass 5 having a radial structure, two layers of belts 6 and 7 covering the outer circumference of the carcass 5, tire rubber 8 covering the outer circumferences of the belts 6 and 7, and right and left side surfaces of the carcass 5. It is provided with sidewalls 9 and 10, bead cores 11 and 12 and bead fillers 13 and 14 that are wound around both ends of the carcass 5.

The precure tread 4 is a base tire 2
It is vulcanized in advance in the mold before being attached to the tread groove having the pattern shown in FIG. The groove pattern of the tread 4 has a rib pattern on the outer side in the radial direction and a block pattern on the inner side in the radial direction. When the tread 4 is worn by 30% to 40% of the total groove depth, the rib pattern changes from the block pattern to the block pattern. It is supposed to change to.

That is, (1) of FIG. 1 is a groove pattern of the ground contact surface in an unused state, and the tread groove is a rib pattern consisting of four grooves 20 along the tire circumferential direction (vertical direction in the drawing). ing. FIG. 1 (2) shows a groove pattern of the ground contact surface when the tread 4 is worn by about 30%, and in this case also, the tread groove is formed along the tire circumferential direction as described above.
The rib pattern is formed by the grooves 20 of the book. (3) of FIG. 1 is a groove pattern of the ground contact surface when the tread 4 is worn by about 40%, and the tread grooves are the above-mentioned four grooves 20 along the tire circumferential direction and these circumferential grooves 20. It is a block pattern composed of a plurality of grooves 25 that intersect with each other in the rotation axis direction of the tire. A sipe 30 is formed at the center of the tread 4. (4) of FIG. 1 shows a groove pattern of the ground contact surface when the tread 4 is worn by about 70%, and in this case as well, the tread grooves are arranged along the tire circumferential direction with four grooves 20 and along the rotation axis direction. It has a block pattern including a plurality of grooves 25. Further, the sipe 30 is formed not only on the center portion of the tread 4 but also on the shoulder portion. Furthermore, a plurality of auxiliary grooves 31 are formed in the shoulder portion of the tread 4 along the rotation axis direction. FIG. 1 (5) shows a groove pattern on the surface where the tread 4 faces the cushion rubber 3, and in this case as well, the tread groove includes four grooves along the tire circumferential direction and a plurality of grooves 25 along the rotation axis direction. The block pattern consists of and. Also, the number of sipes 30 is increased.
Further, a plurality of auxiliary grooves 31 are formed in the shoulder portion of the tread 4 along the rotation axis direction. Further, an auxiliary groove 32 is formed in the shoulder portion of the tread 4 along the tire circumferential direction.

Further, as shown in FIG. 1 (1) and FIG. 2, the radially outer grounding portions 21 facing each other with the tread groove 20 having a rib pattern interposed therebetween are provided in the tread groove 20. They are connected to each other by the connecting portion 40 located. A plurality of each connecting portion 40 is provided at equal intervals in the circumferential direction. The number of connecting portions 40 is appropriately determined according to the tire diameter and the like. Further, the thickness t of the connecting portion 40 is 10 to the total groove depth D.
It is preferably set to 15%. The connecting portion 40 can prevent the ground contact portions 21 from being separated from each other, so that the operation of attaching the tread 4 to the base tire 2 does not become difficult. Further, by connecting the grounding portions 21 to each other by the connecting portion 40, it is possible to reduce movement of the grounding portions during traveling and prevent uneven wear of the tread.

A radial tire 50 according to the second embodiment shown in FIG. 4 includes a carcass 51, two-layer belts 52 and 53 that cover the outer periphery of the carcass, a tread 54 that covers the outer periphery of the belt, and the carcass 51 thereof. 55, 56 covering the left and right side surfaces of the carcass, bead cores 57, 58 wound around both ends of the carcass 51, and the bead filler 5.
9 and 60 are provided.

The tread 54, together with the carcass assembly and the sidewalls 55 and 56, is vulcanized in the mold, as shown in FIG.
The tread groove having the pattern shown in FIG.
The groove pattern of the tread 54 has a rib pattern on the outer side in the radial direction and a block pattern on the inner side in the radial direction. When the tread 54 is worn by 30% to 40% of the total groove depth, the rib pattern changes from the block pattern to the block pattern. It is supposed to change to.

That is, (1) in FIG. 3 is a groove pattern of the ground contact surface in an unused state, in which the tread groove is a rib pattern consisting of four grooves 60 along the tire circumferential direction (vertical direction in the drawing). ing. 3 (2) is a tread 54
Is a groove pattern of the ground contact surface in the state of being worn by about 30%, and in this case also, the tread groove is a rib pattern consisting of the above-mentioned four grooves 60 along the tire circumferential direction. Figure 3
(3) is a groove pattern of the ground contact surface when the tread 54 is worn by about 40%, and the tread groove intersects the four grooves 60 along the tire circumferential direction and these circumferential grooves 60. A block pattern composed of a plurality of grooves 61 along the rotation axis direction of the tire is formed, and the tread 54 is further worn and T.I. W. I. The groove pattern is almost the same until appears.

When the tread is not vulcanized with the precure tread but is vulcanized together with the carcass assembly and the sidewalls in the molding die, for example, a die 70 having a special structure as shown in FIG. 5 is used. That is, the mold 7
On the inner surface of the outer peripheral portion of 0, a convex portion 71 for forming a groove along the circumferential direction in the tread T is formed. Inside the convex portion 71, a pair of cores 72 and a pressing body 73 are built in at intervals in the circumferential direction. The pressing body 73 can be moved in the tire radial direction (vertical direction in the drawing) by a driving mechanism (not shown). Further, the radial inner end portion 73a of the pressing body 73 has a wedge shape, and abuts on the pair of cores 72 via the curved surface 72a. By moving the pressing body 73 inward in the radial direction (downward in the figure), each core 72 is moved to the pressing body 73.
It is pushed by and moves in the tire rotation axis direction (left and right direction in the figure). Further, the core 72 is set to be retracted into the convex portion 71 by the elastic force of a spring (not shown), for example, when the pressing body 73 moves radially outward (upward in the drawing). As a result, the mold 70 is opened and closed by immersing the core 72 in the mold before and after vulcanization molding, as shown in FIG. 5B during vulcanization molding. Like core 7
By projecting 2 into the mold, a portion of the tread groove along the tire rotation axis direction is formed on the radially inner side of the tread T.

According to the tires 1 and 50 having the respective configurations described above, while the groove pattern of the ground contact surface is the rib pattern, the tread groove is deep, so that the wet skid performance is excellent and the tire noise is small. Further, even if the treads 4 and 54 are worn down and the tread groove becomes shallower, the groove pattern on the ground contact surface becomes a block pattern, so that wet skid performance is not deteriorated, and the tread groove is shallow. As a result, the noise does not increase even with the block pattern.

The present invention is not limited to the above embodiment. For example, although the groove patterns on the radially inner side of the tread are all block patterns in the above embodiment, only the groove pattern of the shoulder portion or only the groove pattern of the center portion may be the block pattern,
At least a part of the groove pattern on the radially inner side may be a block pattern. Further, when only the groove pattern of the center portion on the radially inner side of the tread is used as the block pattern, when the groove pattern of the contact surface is a rib pattern with less wear, the grooves along the tire rotation axis on the radially inner side are formed. The air inside will accumulate and cause fatigue damage to the carcass due to temperature rise. Therefore, in that case, it is preferable to provide a heat radiation air passage in the shoulder portion that communicates the outer side of the tire with the tread groove to prevent an increase in temperature.

[0032]

According to the automobile tire of the present invention, the wet skid performance is not deteriorated even when the tread is worn, and the tire noise is not increased. Also, in areas where there is snow in winter, it is possible to use it throughout the season without changing tires according to the season. Further, by using the tread of the tire of the present invention as the precure tread and connecting the ground contact portion with the connecting portion, it is possible to facilitate manufacturing and prevent uneven wear of the tread.

[Brief description of drawings]

FIG. 1 is a diagram showing a tread groove pattern of a tire according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a tire structure of a first embodiment of the present invention.

FIG. 3 is a diagram showing a tread groove pattern of a tire according to a second embodiment of the present invention.

FIG. 4 is a sectional view showing the structure of a tire according to a second embodiment of the present invention.

FIG. 5 is a partial sectional view of a tire molding die of the present invention.

FIG. 6 is a view showing a tread groove pattern of a conventional tire.

FIG. 7 is a view showing a tread groove pattern of a conventional tire.

[Explanation of symbols]

 Two tires 4,54 tread

Claims (2)

[Claims] 1. An automotive vehicle characterized in that a groove pattern on an outer side in a radial direction in a use area of a tread is a rib pattern, and at least a part of a groove pattern on an inner side in the radial direction is a block pattern. tire. 2. A precure tread in which a tread is affixed to a base tire, and radial outer side ground contact portions which face each other across a tread groove having a rib pattern are located in the tread groove. The automobile tire according to claim 1, wherein the automobile tire is connected by a connecting portion.