JP3487781B2 - Pneumatic radial 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 radial tire, and more particularly to a technique for improving ice performance by adjusting a sipe thickness of a block.

[0002]

2. Description of the Related Art Conventionally, so-called studless tires are
As a means for improving the ice performance, a plurality of sipes extending in the tire width direction have been arranged in the block at intervals in the tire circumferential direction. As the sipe shape, a corrugated sipe in which corrugated portions are repeated on the block surface is adopted as a structure for increasing the sipe density in order to enhance the edge effect of the sipe and optimize the block rigidity on an ice road surface. The thickness of the one sipe extends in the tire width direction with a substantially uniform thickness, and its specific thickness is about 0.5 mm or less.

[0003]

However, in the case of a tire having a sipe of uniform thickness as described above, since the tire is thin, water tends to collect at the center of the sipe located in the central region of the block, resulting in sipe centering. A water film is likely to be formed on the block surface in the section, which leads to slippage on the ice road surface. That is, in the end region of the block, the sipe may open in the main groove, etc., and the water held by the sipe is easily removed as the tire rotates, but in the center region of the block, the sipe opens on the tire surface. However, since the sipes are thin, the water held by the sipes on the ice road surface is difficult to remove, and a water film easily accumulates on the block surface at the center of the sipes.

An object of the present invention is to provide a pneumatic radial tire capable of preventing the accumulation of a water film at the center of the sipe and improving the ice performance.

[0005]

DISCLOSURE OF THE INVENTION The present invention is a pneumatic radial tire in which a groove and a block divided by the groove are provided in a tire tread portion, wherein the block includes:
A composite sipe that extends in the tire width direction is arranged, and the composite sipe has a sipe center portion that constitutes a block center region in the tire width direction, and a main groove or tire that is continuous from both sides or one side of the sipe center portion. And a sipe end portion that opens to the shoulder end portion to form a block end region, and the thickness of the sipe center portion of the composite sipe is formed to be thicker than the thickness of the sipe end portion. Tires.

As described above, in the tire of the present invention, the thickness of the central portion of the sipe located in the central region of the block is formed to be thicker than the thickness of the end portion of the sipe. The water taken into the center of the sipe is easily removed outside the tire as the tire rotates, and water is prevented from collecting in the center of the sipe. as a result,
Formation of a water film on the surface of the block at the center of the sipe is suppressed, and slippage on the ice road surface is prevented. Also, the thickness of the sipe end is formed thinner than the center of the sipe, but since the sipe end opens to the main groove or the tire shoulder end to form the block end region, the sipe end during running is The water taken into the part is easily removed outside the tire as the tire rotates. Therefore, the sipe of the present invention can improve the performance on ice in its entire thin structure.

Further, in the case of a tire in which the sipe end portion is constituted by a straight sipe with respect to the corrugated sipe center portion, a block at the time of grounding is further provided by disposing the sipe center portion having a large sipe thickness. The free movement of the central area can be restricted by the block end area where this straight sipe end is arranged. Moreover, this block end region has rigidity as compared with the block center region.
Therefore, the tire of the present invention can exert the water removing effect on the center of the sipe while preventing the occurrence of step wear that tends to occur in the region between the sipes in the center region of the block as much as possible. In addition, since the block rigidity is prevented from being lowered as a whole as a whole, the block does not fall down when the vehicle comes into contact with the ice road surface during traveling, and the so-called edge effect of the sipe is not deteriorated.

Therefore, the tire of the present invention is excellent in the water removing effect of sipes in the block, and further retains the edge effect and the adhesion effect on the ice road surface, so that the performance on ice as a whole can be improved. it can.

[0009]

1 is a schematic development view of a tread pattern showing an embodiment of a pneumatic radial tire according to the present invention. FIG. 2 is an enlarged schematic plan view of a block arranged in the tire tread portion of the same embodiment.

In the figure, reference numeral 1 is a tire tread portion, and 2 is a block provided on the tire tread portion 1.
The block 2 is divided into a main groove 3 extending in the tire circumferential direction and a lateral groove 4 extending in the tire width direction. In addition,
In FIG. 1, TC indicates a tire tread center line and SH indicates a shoulder end portion.

In this block 2, as shown in the drawing, composite sipes 5 extending in the tire width direction are arranged at equal intervals in the tire circumferential direction. Each of these composite sipes 5 has a corrugated sipe center portion 5a forming a block center region 2a in the tire width direction, and a main groove 3 or a tire shoulder end portion SH which is continuous from both sides of the sipe center portion 5a. And a linear sipe end portion 5b which is opened to form a block end region 2b. Further, as shown in FIG. 2, the thickness T ₁ of the sipe center portion 5a of the composite sipe 5 is formed to be thicker than the thickness T ₂ of the sipe end portion 5b. Incidentally. In FIG. 2, Y is the block width, Y ₁ is the width of the sipe center portion 5a, and Y ₂ is the width of the sipe end portion 5b.

Therefore, in the tire of this embodiment, since the thickness T ₁ of the sipe center portion 5a located in the block center region 2a is formed to be thicker than the thickness T ₂ of the sipe end portion 5b, the tire runs on the ice road surface. While sipe center 5a
The water taken in becomes easy to be drained to the outside of the tire as the tire rotates, and the pool of water in the sipe center portion 5a is prevented. As a result, formation of a water film on the surface of the block 2 at the sipe center portion 5a is suppressed,
Prevents slippage on ice roads.

In the tire of this embodiment, the thickness T ₂ of the sipe end portion 5b is thinner than the thickness T ₁ of the sipe center portion 5a, but the sipe end portion 5b has the main groove 3 or the tire shoulder end portion. Since the block end region 2b is formed by opening to the SH, the water taken into the sipe end portion 5b during traveling is likely to be drained to the outside of the tire as the tire rotates. Moreover, the thickness T ₂ of the sipe end portion 5b is made thin instead of being the same as the thickness T ₁ of the sipe center portion 5a. Further, the sipe end portion 5b is formed with respect to the corrugated sipe center portion 5a.
Is constituted by a linear sipe, the free movement of the block center region 2a at the time of grounding by arranging the sipe center portion 5a having a large sipe thickness is restricted by the block end region 2b, and the block end region 2b is restricted. It prevents the decrease in rigidity. Therefore, the tire according to the present embodiment can exert the water removing effect of the sipe central portion 5a together with the adhesion to the ice road surface and the edge effect while suppressing the occurrence of step wear between sipes as much as possible.

By the way, in fact, specifically how to set the width Y ₂ of the width Y ₁ and sipe end 5b of the sipe central portion 5a of the composite sipe 5, further sipe central portion 5a of the composite sipe 5 How to specifically set the thickness T ₁ and the thickness T ₂ of the sipe end portion 5b is a problem, but the width Y ₁ of the sipe center portion 5a of the composite sipe 5 is 0.8Y or less of the block width Y. , The width Y ₂ of the sipe end portion 5b is set to 0.1 Y or more of the block width Y, and the sipe center portion 5
The thickness T ₁ of a is 1.5T ₂ of the thickness T ₂ of the sipe end 5b.
It is preferably 4T ₂ . Particularly, in the case of a radial tire for passenger cars, the thickness T ₂ of the sipe end portion 5b should be further set to 0.1 to 0.5 mm, and the thickness T ₁ of the sipe center portion 5a should be set to 0.6 mm or less. Is preferred.

The width Y ₁ of the sipe center portion 5a of the composite sipe 5
For tires that have been set to exceed the block width Y of 0.8Y,
Since the setting range of the thick sipe center part 5a is large and the setting range of the thin sipe end part 5b is too small, the free movement of the block center region is controlled by the block end region 2b in which the sipe end part 5b is arranged. It becomes difficult to regulate with, and step wear easily occurs between the composite sipes.

A tire in which the thickness T ₁ of the sipe center portion 5a is less than 1.5T ₂ of the thickness T ₂ of the sipe end portion 5b is
Sipe center 5a thickness T ₁ is the sipe end portions 5b of the thickness T ₂
Since the movement of the sipe center portion 5a by the sipe end portion 5b is excessively restricted, the step wear in the inter-sipe region can be suppressed, but the water removing effect becomes poor. On the other hand, the thickness T ₁ of the sipe center portion 5a is set to the sipe end portion 5
When the thickness T ₂ of b is set to exceed 4T ₂ , the thickness T ₁ of the sipe center portion 5a becomes excessively thicker than the thickness T ₂ of the sipe end portion 5b, and therefore the water removing effect is not good. But
The regulation of the sipe end portion 5b with respect to the movement of the sipe center portion 5a becomes insufficient, step wear is likely to occur in the inter-sipe region, and the edge effect of the sipe is deteriorated.

In particular, for pneumatic radial tires for passenger cars
In case of thickness T₂Thickness is less than 0.1 mm
Is too thin, resulting in poor workability.
Mi T ₂Is thicker at the sipe end that exceeds 0.5 mm
The sipe end against the movement of the sipe center 5a
5b becomes insufficiently regulated, causing a step in the area between sipes.
Wear is likely to occur and the sipe edge effect is worse.
To do. In the case of pneumatic radial tires for passenger cars,
Thickness T of sipe center₁Is more than 0.6 mm,
Step wear in the inter-pile region is likely to occur.

The sipe center portion 5a of these composite sipes 5
Y ₁ , the width Y ₂ of the sipe end portion 5b, the thickness T ₁ of the sipe center portion 5a, and the thickness T ₂ of the sipe end portion 5b are not limited to pneumatic radial tires for passenger vehicles. Needless to say, bus tires, light truck tires, and so-called minivan tires can also be appropriately designed and applied according to the tire size. Further, the composite sipe 5 of this embodiment is a sipe that is open at both ends, but can be applied to a sipe that is open at one end.

Further, in the composite sipe 5 of this embodiment, the sipe center portion 5a adopts a corrugated sipe and the sipe end portion 5b adopts a linear sipe, but it is not limited to this. For example, the sipe center portion 5a and the sipe end portion 5b are both corrugated sipes, the sipe center portion 5a and the sipe end portion 5b are both linear sipes, and the sipe center portion 5a is a linear sipes and the sipe end portion 5b is also corrugated sipes. Can be adopted.

Further, although the composite sipe 5 of this embodiment is constructed as a sipe extending in parallel to the tire width direction, the present invention is not limited to this, and an inclined sipe formed at an angle to the tire width direction. Can also be applied to. Furthermore, the block according to the present embodiment has a so-called quadrangular surface block 2 having block edge portions parallel to the tire width direction and having block edge portions parallel to the tire circumferential direction.
The composite sipe 5 is arranged in this block, and a block having a rhombic shape, for example, which is angled with respect to the tire width direction or the tire circumferential direction, has a parallel or inclined angle with respect to the tire width direction. It is also possible to arrange the compound sipe 5 that it has.

Further, the composite sipes 5 of this embodiment are arranged in one block 2 at intervals of six,
In particular, the number is not limited. Furthermore, the composite sipe of the present invention can be arranged in combination with a normal sipe having a constant thickness over the entire tire width direction.

In order to mold the composite sipe of the present invention into a block, blades having different thicknesses are combined and installed in a tire molding die as one sipe blade.
It can be easily manufactured by adopting a conventional tire manufacturing method.

[0023]

EXAMPLE An example tire having a tire size of 185 / 70R14 having the tread pattern of FIG. 1 was prototyped and mounted on a passenger car having a displacement of 2000 cc to obtain ice braking performance, ice acceleration performance, ice turning performance and step wear resistance performance. Each test was conducted. Table 1 shows the test results. In addition,
The width Y ₁ of the sipe center portion of the composite sipe in the example tire and Comparative Examples 2 to 7 described later is 18 mm, and the width Y ₂ of the sipe end portion is 3.5 mm. The block width Y is 25 mm in each of the examples and the comparative examples. The thickness T _{1 at the} center of the sipe and the thickness T ₂ at the end of the sipe are as shown in Table 1.

For comparison, the thickness T at the center of the sipe is
Comparative Example 1 tire, which is the same as the Example 1 tire, except that ₁ and the thickness T ₂ of the sipe end portion are the same (the entire thickness of one sipe is all the same), and the same test as the above example I went. In addition, a comparative tire similar to the tire of Example 1 was prototyped except for the contents shown in Table 1, and the same tests as those of the above-mentioned Examples were conducted.

The braking performance on the ice road surface is 40
The full lock braking distance from km / h was measured, and Comparative Example 1
The tire measured value was set to 100 and displayed as an index, and the reciprocal value was used for evaluation. The larger the value, the better the braking performance on the ice road surface.

The acceleration performance on the ice road surface was evaluated by measuring the running time from the stopped state to 30 m, displaying the index of the measured value of the tire of Comparative Example 1 as 100, and the reciprocal value thereof. The larger the value, the better the acceleration performance on the ice road surface.

The ice turning performance was evaluated by measuring the lap time on a lemniskate curve (8-shaped) on the ice road surface, displaying the index value with the measured value of the tire of Comparative Example 1 being 100, and the reciprocal value thereof. The higher the number,
This shows that the turning performance on the ice road surface is good.

A step wear test between sipes was carried out on a general road surface with 8
The height difference of the step wear appearing on the surface of the block after running for 000 km was measured at three points on one tire, and the average value of the four tires mounted was calculated as the average step wear amount. The measured value of one tire was set to 100 and displayed as an index, and the reciprocal value was used for evaluation. The larger the value, the better the step wear resistance on the ice road surface.

[0029]

[Table 1]

As can be seen from Table 1, the example tires have improved ice braking performance, ice acceleration performance and ice turning performance while suppressing the deterioration of the step wear resistance as much as possible, as compared with the comparative example 1 tire.

On the other hand, the width Y ₁ of the sipe center portion of the composite sipe
In Comparative Example 2 in which the block width Y exceeds 0.8Y, the ice performance is improved, but the effect of preventing step wear between the composite sipes is not sufficient.

In Comparative Example 3 in which the thickness T ₁ at the center of the sipe is less than 1.5T ₂ which is the thickness T ₂ at the end of the sipe, the step wear in the region between the sipes can be suppressed, but the water removing effect is poor and the ice performance is low. Is not recognized.

In Comparative Example 4 in which the thickness T ₁ at the center of the sipe exceeds 4T ₂ which is the thickness T ₂ at the end of the sipe, the step wear in the inter-sipe region remarkably occurs, and the improvement of the ice performance is not recognized.

The thickness T ₁ of the sipe center portion 5a is 0.6 mm.
It is recognized that Comparative Example 5 exceeding 5 is excessively thick, so that step wear in the inter-sipe region is likely to occur.

In Comparative Example 6 in which the thickness T ₂ of the sipe end portion is less than 0.1 mm, the workability is poor because the thickness is excessively thin. In Comparative Example 7 in which the thickness T ₂ of the sipe end portion exceeds 0.5 mm, step wear is likely to occur in the inter-sipe region.

[0036]

As described above, according to the present invention, a block has a sipe center portion which constitutes a block center region in the tire width direction, and a main groove or a tire shoulder end which is continuous from both sides or one side of the sipe center portion. Pneumatic radial having a composite sipe formed by forming a sipe end portion that opens into a portion to form a block end region, and in which the sipe center portion is formed thicker than the sipe end portion. Tires.

Therefore, while suppressing the step wear in the region between the sipes as much as possible, the water removing effect of the central part of the sipes is exerted, the formation of the water film on the block surface in the central parts of the sipes is suppressed, and the sipes having the uniform thickness are arranged. The ice performance is improved as compared with the conventional tire.

[Brief description of drawings]

FIG. 1 is a schematic development view of a tread pattern showing an embodiment of a pneumatic radial tire according to the present invention.

FIG. 2 is an enlarged schematic plan view of a block arranged in a tread portion of the same embodiment.

[Explanation of symbols]

1 tire tread portion 2 block 3 main groove 4 lateral groove 5 composite sipe 5a sipe center 5b sipe end SH tire shoulder end Y block width Y ₁ sipe center width Y ₂ sipe end width T ₁ sipe center Thickness T ₂ Sipe end thickness

Claims (3)

(57) [Claims] 1. A pneumatic radial tire in which a groove and a block divided by the groove are provided in a tire tread portion, wherein a composite sipe extending in a tire width direction is arranged in the block. Is a corrugated sipe center that constitutes a block center region in the tire width direction, and a block end region is formed by opening to the main groove or the tire shoulder end while continuing from the sipe center on both sides or one side thereof. A pneumatic radial tire comprising a straight sipe end, wherein the sipe center of the composite sipe is formed thicker than the sipe end. Wherein the width Y ₁ Gab sipe central composite sipe
The lock width Y is 0.8Y or less, and the width Y ₂ of the sipe end is
The width of the sipe is T, which is 0.1 Y or more of the width Y of the sipe.
₁ is 1.5T _{2 to} 4T ₂ which is the thickness T ₂ of the sipe end.
Item 1. The pneumatic radial tire according to item 1. 3. The thickness T _{1 of the} center of the sipe is 0.6 mm or less.
Below, the thickness T ₂ of the sipe end is 0.1 to 0.5 mm
The pneumatic radial tie for passenger cars according to claim 2.
Ya.