JP3473904B2 - Pneumatic tire - Google Patents

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 tread pattern having a plurality of blocks each having a plurality of sipes, and is particularly useful as a studless tire.

[0002]

2. Description of the Related Art Conventionally, it has been known that a plurality of sipes are arranged in each part (center part, mediate part, shoulder part) of a tire pattern for the purpose of improving the ice performance of a studless tire. As the shape of such a sipe, a sipe having a straight or corrugated cross-sectional shape is generally used. The number of sipes tends to increase in recent years because the edge effect, the water removing effect, and the adhesion effect are improved by forming such sipes in the block.

However, when the number of sipes is increased to increase the density of sipes, the number of edges increases, but the rigidity of the entire block decreases and the sipes fall excessively, so that the ground contact area decreases. There is a problem that the ice braking property is deteriorated. Further, if the sipes fall down excessively, the ground pressure becomes uneven on the surface of each block divided by the sipes, and step wear is likely to occur, which causes a difference in the amount of wear of both blocks with the sipes as the boundary.

On the other hand, the sipes formed on the blocks are
There is a double-sided open sipe (both sides open sipe) that opens on both sides on the side wall of the block, a closed sipe (closed sipe) that neither side opens, and a single-sided open sipe (one-sided open sipe) that opens on only one side. It is known that the closing sipe is the most difficult to reduce the rigidity of the block.

JP-A-6-219108 proposes an ice / snow road tire in which a closed sipe and a one-sided open sipe are combined and arranged in a block in order to improve the uneven wear resistance and the ice braking performance at the same time. Has been done.

[0006]

However, in this ice and snow road tire, the closed ends of the closed sipe and the one-sided open sipe are arranged in the vicinity of the side wall of the block, and the sipe divides the block except at the end of the block. I'm doing
The effect of suppressing the collapse was small near the center of the block where the collapse amount of the block was the largest. For this reason, the sipe density cannot be sufficiently increased, and there is a limit in improving the uneven wear resistance or the ice braking performance.

Although there are pneumatic tires which are discontinuous by dividing the sipes extending from the side walls on both sides of the block in the middle, in order to maintain durability, the distance between the closed ends of the divided portions is to some extent. Since it needs to be large, there is a limit in increasing the sipe density.

Therefore, an object of the present invention is to effectively suppress the collapse especially in the vicinity of the center of the block even when the sipe density is increased, so that good ice braking property can be exhibited.
Moreover, it is to provide a pneumatic tire in which uneven wear is unlikely to occur.

[0009]

The above object can be achieved by the present invention as described below. That is, the pneumatic tire of the present invention, divided into three parts in the pneumatic tire provided with a tread pattern having a plurality of blocks having a plurality of sipes, the block on either side of the center of the tire width direction 2
Around the boundary line of the book, the closing ends of a plurality of sipes extending from both sides in the tire width direction are arranged, and a compound extending from the center side in the tire width direction to both sides toward substantially the center between the closing ends.
Provided the number of closed sipes, said two of the closed end of both sides
It is characterized in that it is arranged near the boundary line of.

In the above description, the closed ends of a plurality of one-sided open sipes extending from the side walls on both sides of the block are arranged near two boundary lines that divide the block into three at both sides in the center in the tire width direction. It is preferable that a plurality of closing sipes extending from the center side in the tire width direction toward both sides toward substantially the center between the closing ends are provided, and the closing ends on both sides are arranged near the two boundary lines. .

Further, it is preferable that the closed end of the one-sided open sipe and the closed end of the closed sipe are arranged within a region of 5 mm or less in the tire width direction along the boundary line.

Further, at least one of the closed sipe and the one-sided open sipe preferably has a wavy or zigzag cross section.

[0013] According to the advantageous effects present invention, in a region along the two boundary lines divided into three blocks at each side of the center of the tire width direction, the continuous portion of the suppressing blocks collapsing of the block is formed Therefore, the collapse especially near the center of the block can be effectively suppressed. That, along with placing the closed ends of a plurality of sipes extending from both sides in the tire width direction in the vicinity of the boundary line, in the tire width direction toward the substantially center between the closed end
Provide a plurality of closed sipes extending from the central side to both sides,
Since the closed ends on both sides are placed near the two boundaries,
Blocks are continuous in the area along the boundary line, and there is little (or no) overlap between the sipe ends that extend from both sides in the continuous part, and since the closed ends do not approach each other extremely, the continuous part collapses the block. Has a reinforcing effect of suppressing The reinforcing effect, because obtained at both sides of the position of the center of the block, it is possible to effectively suppress collapsing of the blocks in the vicinity of the center, whereby, even when increasing the sipe density, good ice braking The property can be exhibited and uneven wear can be made less likely to occur.

As described above, the block is divided into three, the closed ends of a plurality of one-sided open sipes extending from the side walls on both sides are arranged in the vicinity of the boundary line, and the tire width direction is set substantially toward the center between the closed ends. If a plurality of closed sipes extending from the center side to both sides are provided and the closed ends on both sides are arranged near the boundary line between the two lines, the side wall side of the block of the one-sided open sipes will have an appropriate collapse amount. By providing the above-mentioned reinforcing effect near the closed end of the one-sided opening sipe, it is possible to properly suppress the collapse of the entire block, and to provide the ice braking property and the uneven wear resistance. At the same time, it can be improved significantly.

When the closed end of the one-sided open sipe and the closed end of the closed sipe are arranged within a region of 5 mm or less in the tire width direction along the boundary line, both sides of the block are continuous. Since the overlapping of the sipe ends extending from the sipe becomes smaller, the effect of suppressing the collapse of the block by the continuous portion becomes greater.

When at least one of the closed sipe and the one-sided open sipe has a wavy or zigzag cross section, the edge component with respect to the lateral force increases,
Where uneven wear is likely to occur, due to the above-described effects, it is possible to exhibit good ice-braking property and prevent uneven wear from occurring.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the pneumatic tire of the present invention includes a tread pattern T having a plurality of blocks 1 in which a plurality of sipes 10 and 11 are formed. In the present embodiment, an example is shown in which a block 1 divided by a circumferential groove 2 and a lateral groove 3 is formed and five rows of blocks 1 are arranged in the tire width direction.

In the present invention, the block 1 is divided into two in the vicinity of the center in the tire width direction by the boundary line, or the block 1 is divided into three on both sides of the center.
In the present embodiment, as shown in FIG. 2, the block 1 is divided into two boundary lines B on both sides in the center in the tire width direction.
An example is shown in which L is divided into three parts, and one side opening sipe 10 is provided on both sides of the boundary line BL and a closing sipe 11 is provided in the center thereof.

A plurality of one-sided open sipes 10 are formed extending from the side walls 1a, 1b on both sides of the block 1 toward the center side, respectively, and their closed ends 10a are arranged near the two boundary lines BL.

The cross-sectional shape of the one-sided opening sipe 10 may be a straight line or a shape close to a straight line, but a wavy shape or a zigzag shape is preferable for the reason described above. The same applies to the closed sipe 11. The wavy or zigzag shape is not limited to a shape close to a sine wave, and may be any shape such as a wavy line in which straight lines and curved lines are alternately combined or a shape close to a rectangular wave. Further, the one-sided opening sipe 10 may partially have a straight line portion having a straight cross-sectional shape. When the straight portion is provided, it is preferably provided at the end of the non-straight portion. By making the end portion linear, it is possible to prevent the end portion from opening at an acute angle with respect to the groove, and the acute angle portion from being easily damaged.

The period of the unevenness of the cross-sectional shape of the one-sided opening sipe 10 (for example, the distance between the convex-convex apex portions) is preferably 1.5 to 5 mm in order to suitably express the characteristics of a so-called corrugated sipe, and the amplitude ( The sum of the heights of the tops on both sides) is preferably 1.5 to 5 mm.

On the other hand, the closing sipe 11 extends from the center side in the tire width direction toward both sides toward substantially the center between the closing ends 10a of the one-side opening sipe 10, and the closing ends 11a on both sides are near two boundary lines BL. It is located at.

That is, the closed ends of the plurality of sipes extending from one side in the tire width direction are arranged near the boundary line, and the sipes are extended from the other side in the tire width direction toward the approximate center between the closed ends. The end is arranged near the boundary line. As a result, a continuous portion of the block that suppresses the collapse of the block is formed, so that the collapse of the block can be effectively suppressed.

In the present invention, assuming that the position of the boundary line BL is equal to the distance from the closing end 10a and the distance from the closing end 11a, the position of the dividing line BL into three is the center of the block. Block width 20 to 7 centered at
It is preferably arranged in the 0% area. Further, it is preferable that the position of the boundary line BL divided into two is arranged in an area within 30% of the block width centered on the center of the block.

Further, in the present invention, for example, the closed end 10a of the one-sided open sipe 10 and the closed end 11a of the closed sipe 11 are provided.
Is preferably arranged in a region of 5 mm or less in the tire width direction along the boundary line BL, and further preferably in a region of 3 mm or less in the tire width direction.
In the area exceeding 5 mm in the tire width direction along the boundary line,
When the closed end 10a and the closed end 11a are arranged, the overlapping of the sipes 10, 11 extending from both sides becomes large, so that the reinforcing effect of suppressing the collapse of the block tends to decrease at that portion. Or sipe 1 extending from both sides
0 and 11 are too far apart, the sipe density tends to be small, and the edge effect tends to be insufficient.

The groove width of the one-side opening sipe 10 and the closing sipe 11 is preferably 0.2 to 0.7 mm. The groove depth of the one-sided opening sipe 10 and the closed sipe 11 is preferably 30 to 80% of the main groove depth. The sipes 10 and 11 are generally formed to be perpendicular to the block surface, but the sipes may be slightly inclined (for example, 15 ° or less) with respect to the normal line of the block surface. .

In the present invention, the number of edges can be increased and the edge effect can be further enhanced by increasing the number of auxiliary sipes 11 and increasing the sipe density while suppressing the collapse of the block 1. From this point of view, in the present invention,
The sipe density is preferably 0.1 to 0.3 mm / mm ² ,
0.15-0.25 mm / mm < ² > is more preferable.

The pneumatic tire of the present invention is the same as a normal pneumatic tire except that it has the tread pattern T as described above, and any conventionally known materials, shapes, structures, manufacturing methods, etc. are adopted in the present invention. it can.

The pneumatic tire of the present invention is particularly useful as a studless tire because it has the above-mentioned effects and is excellent in ice performance.

[Other Embodiments] Other embodiments of the present invention will be described below.

(1) In the above-described embodiment, the block is divided into three parts by two boundary lines on both sides of the center in the tire width direction, and one side opening sipe is closed on both sides of the boundary line. An example is shown in which sipes are provided so that their closed ends are located substantially on the boundary line. However, it is assumed that sipes extending from both sides have a large overlapping amount or that they are divided into two parts near the center in the tire width direction. As shown in FIGS. 3 (a) and 3 (b).

As shown in FIG. 3 (a), the overlapping amount of the ends of the sipes 10 and 11 extending from both sides is larger than that in FIG. In the overlapping portion near the boundary line BL, the ends of the sipes 10 and 11 have substantially the same shape and are arranged at positions shifted in the tire circumferential direction. In the present invention, it is possible to reduce the overlapping amount, and the closing end 10a and the closing end 11a are arranged on a straight line, and further, the closing end 10a and the closing end 1 are arranged.
You may arrange | position so that 1a and the boundary line BL may be left | separated.
However, it is preferable to arrange it in a region having a certain width or less along the boundary line BL as described above. At this time, the overlapping amount of the sipes may change depending on the part.

As shown in FIG. 3B, the closed ends 13a and 14a of the sipes 13 and 14 extending from both sides are arranged near the boundary line BL that divides into two in the vicinity of the center in the tire width direction. Further, the sipes 13 and 14 are provided such that their reference lines are slightly inclined from the tire width direction. As described above, the sipe in the present invention does not need to be parallel to the tire width direction, but the angle formed by the direction of the reference line and the tire width direction is preferably 0 to 45 °.

(2) In the above-described embodiment, an example of the block pattern as shown in FIG. 1 is shown, but the block pattern is not limited to this shape, and a parallelogram, a V-shape, a pentagon, or a curved tone is used. It can be a block. In addition, a block having a groove up to the vicinity of the center or the vicinity of the edge or a part of the land may be continuous in the circumferential direction. An example of another preferable pattern in the present invention is as follows.

In this example, as shown in FIG. 4, the block 1 is divided into circumferential grooves 2, lateral grooves 3 and 5, and oblique grooves 4.
Is formed, and six rows of blocks 1 are arranged in the tire width direction. Further, the block 1 has a different shape depending on the position in the tire width direction, but in any shape, the peripheral edge thereof has a zigzag shape. In such a tread pattern T, the one-sided open sipe 10 and the closed sipe 11 have the shapes and arrangements shown in FIG.
Are formed.

(3) In the above-described embodiment, the sipes extending from the side wall of the block are all open to the groove adjacent to the block, but they may be closed ends that do not open to the side wall of the block. , Can be used properly according to the pattern configuration.

[0037]

EXAMPLES Examples and the like specifically showing the constitution and effects of the present invention will be described below. In addition, each performance evaluation of the tire was performed as follows. The sipe density was adjusted by changing the sipe interval.

(1) Ice braking performance tires are used as actual vehicles (domestic 2000cc class FF sedan)
The vehicle was mounted on a vehicle and the vehicle was run on a frozen road surface under a load condition of one passenger, and braking force was applied at a speed of 40 km / h to fully lock the vehicle. In addition, the evaluation is shown by the index display when the conventional product (Comparative Example 1) is 100,
The larger the value, the better the result.

(2) Abrasion resistance performance The amount of step wear (step between the blocks on both sides of the sipe due to wear) when running on a paved road for 8000 km was measured and evaluated by an index. The conventional product (Comparative Example 1) was evaluated as 10
It is indicated by an index when 0 is set, and the larger the value, the better the result. Example 1 In a tread pattern as shown in FIG. 1, sipes having the shape shown in FIG.
A 70R14 radial tire was manufactured. Table 1 shows the results of the above performance evaluations using this tire.
Sipe depth 7mm, groove width 0.3mm, amplitude 1.5m
m, cycle 4.0 mm, sipe density 0.20 mm / mm
^2. The width of the overlapping area of the sipe ends was set to 0.6 mm.

Example 2 In a tread pattern as shown in FIG.
A sipe having the shape of (a) was formed in the following size to manufacture a radial tire of size 185 / 70R14. Table 1 shows the results of the above performance evaluations using this tire. Sipe depth 7mm, groove width 0.3mm, amplitude 1.5mm, cycle 4.0mm, sipe density 0.23m
The width was m / mm ² and the width of the overlapping region of the sipe end portion was 2.3 mm.

Comparative Example 1 (Conventional product) Example 1 except that the corrugated sipes shown in FIG. 5 were formed with a sipes density of 0.18 mm / mm ² (conventional corrugated sipes). Similarly, size 18
A radial tire of 5 / 70R14 was manufactured and the above performance evaluations were performed. The results are shown in Table 1.

Comparative Example 2 In Comparative Example 1, only the sipe density was increased to 0.2.
In the same manner as in Comparative Example 1 except that 1 mm / mm ² was used,
We manufacture radial tires of size 185 / 70R14,
The above performance evaluations were performed. The results are shown in Table 1.

[0043]

[Table 1] As the results of Table 1 show, in the example, the ice braking performance was better than the conventional product due to the effect of suppressing the collapse of the block. On the other hand, in Comparative Example 2 in which only the density of the conventional corrugated sipe was increased, the ice braking performance was slightly improved, but the wear resistance performance was decreased.

[Brief description of drawings]

FIG. 1 is a plan view showing a tread surface of an example of a pneumatic tire of the present invention.

FIG. 2 is an enlarged view of an essential part showing an example of a block according to the present invention.

FIG. 3 is an enlarged view of an essential part showing another example of the block in the present invention.

FIG. 4 is a plan view showing a tread surface of another example of the pneumatic tire of the present invention.

FIG. 5 is an enlarged view of a main part showing an example of a block adopted in a comparative example.

[Explanation of symbols]

1 block 10 One side opening sipe 10a closed end 11 closed sipe 11a closed end 13-14 sipes 13a-14a closed end T tread pattern BL border

Claims (4)

(57) [Claims] A pneumatic tire having a 1. A plurality of tread pattern having a plurality of formed blocks the sipes, the block in the vicinity of the two boundary lines to be divided into three parts at both sides of the center of the tire width direction, the tire The closed ends of a plurality of sipes extending from both sides in the width direction are arranged, and extend from the center side in the tire width direction to both sides toward the approximate center between the closed ends.
Multiple closing sipes are provided, and the closing ends on both sides are
A pneumatic tire characterized by being arranged near two boundary lines. 2. Closed ends of a plurality of one-sided opening sipes extending from side walls on both sides of the block are respectively arranged near two boundary lines that divide the block into three parts on both sides in the center in the tire width direction, and 2. A plurality of closing sipes extending from the center side in the tire width direction to both sides toward substantially the center between the closing ends, and the closing ends on both sides are arranged near the boundary line between the two. Pneumatic tire. 3. The pneumatic tire according to claim 2, wherein the closed end of the one-sided open sipe and the closed end of the closed sipe are arranged within a region of 5 mm or less in the tire width direction along the boundary line. 4. The pneumatic tire according to claim 2, wherein at least one of the closed sipe and the one-sided open sipe has a wavy or zigzag cross-sectional shape.