JP3518830B2 - 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 suitable for use in passenger cars, light trucks and the like, and more particularly to simultaneous improvement of ice and snow road performance and wear resistance thereof.

[0002]

2. Description of the Related Art In a pneumatic tire, in particular, a studless tire, the ice and snow road performance can be improved by imparting water-removing, sticking and scratching effects to the tire contact surface. . Conventionally, in order to realize these three great effects, various techniques for combining three means of a tire structure, a tread pattern, and rubber characteristics have been developed. Among them, in a pattern, as a means for increasing the effects of water removal, adhesion, and scratching, a plurality of circumferential grooves and a ground plane of a block divided by lateral grooves intersecting these circumferential grooves, Means are used to make heavy use of sipes. This is because, when considering one block of a rectangular parallelepiped, the more the sipes are and the thicker the sipes are, the more easily the block is deformed by a constant force, the lower the block rigidity becomes, and the adhesive effect can be provided.

[0003]

However, if the number of sipes is increased too much in one block, the rigidity becomes too low,
The block falls down, which rather reduces the adhesive effect and wear resistance. On the other hand, if the number of sipes is reduced too much within one block, it will no longer function as a studless tire having ice and snow road performance.

On the other hand, if the sipes are made too thick,
Although the water removal effect is increased, the block rigidity is too low, so the adhesive effect and scratching effect are decreased. At the same time, the wear resistance also decreases. On the other hand, if the sipe thickness is made too thin, the block rigidity can be moderately reduced and the adhesive effect and the scratching effect can be increased, but the water removal effect is reduced and the ice and snow road performance cannot be sufficiently improved as a whole. . In this way, simply increase / decrease the number of sipes in one block,
By simply increasing or reducing the sipe thickness, water removal, adhesion,
It is not always sufficient to increase the scratching effects in a comprehensive manner and to simultaneously improve the snow and snow road performance and the wear resistance performance.

The object of the present invention is to increase the effects of water removal, adhesion, and scratching on the tire tread surface in a comprehensive manner, and to improve the performance of ice and snow roads and wear resistance which are trade-offs at the same time. The point is to provide tires.

[0006]

As a result of extensive studies to solve the above problems, there was a performance limit to using sipes of the same thickness for blocks in a tire tread, and therefore there was a constant thickness within one block. By using two or more types of sipes with different thicknesses instead of using sipes, it is possible to simultaneously satisfy the trade-offs by increasing the number of sipes and maintaining the block rigidity. In addition, it was found that braking and driving performance can be secured on ice and snow roads.

That is, the invention of claim 1 is a pneumatic tire having a tire tread surface, which is provided with a block divided by a plurality of circumferential grooves and lateral grooves intersecting with the circumferential grooves. A pneumatic tire having a surface provided with a block having a plurality of types of sipes having different sipes thickness and extending in the tire width direction within one block. As a result, the effects of water removal, adhesion, and scratching on the tire tread surface can be comprehensively increased, and the trade-off between ice and snow road performance and wear resistance performance can be simultaneously improved.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a model diagram showing an embodiment of the present invention when one block in a tread pattern is considered as one rectangular parallelepiped block. FIG. 3 is a model view of a conventional tire. All are unit blocks of the same size. In both figures, 1 is a block, 2 is a thin sipe, and 3 is a thick sipe. Both are configured as sipes extending in the tire width direction, the distance between sipes and the depth of sipes are both constant, and the block of the present invention in FIG. 1 is the same as the number of sipes in FIG. However, the thickness d of each sipe formed in the block shown in FIGS. 1 and 3 and the block shown in FIG. 2 described later is different, and as described above, the sipe 2 and the thick sipe 3 are formed. . In the present invention, since the two sipes are replaced by the thin sipes 2, the block rigidity of the entire block is higher than that of the conventional tire shown in FIG.
Therefore, compared with the conventional tire, the adhesion effect and the scratching effect can be increased, and the wear resistance performance can be improved. In addition, although a thin sipe 2 is used in part, a thick sipe 3 is also used, and since the number of sipes is the same as that of the conventional tire, the reduction of the water removal effect can be suppressed to the extent that there is no problem. it can. On the other hand, although not shown in the figure, in the block in which all the sipes shown in FIG. 3 are thin sipes, the block rigidity is increased, but the sipes are easily blocked, so that the water removal effect is reduced and the ice and snow road performance is improved. I can't plan enough. Therefore, by mixing the thin sipe 2 and the thick sipe 3, the block rigidity can be increased, the adhesive effect and the scratching effect can be increased, and the wear resistance performance can be improved, and at the same time, the water removing effect can be exerted. As a result, it is possible to improve ice and snow road performance and wear resistance performance at the same time.

From this point of view, if the sipe density shown in FIG. 1 is further increased and the block rigidity is made the same as that of the conventional tire, the ice and snow road performance can be further improved as compared with the conventional tire. Figure 2
Is an example in which the thin sipes 2 are frequently used in the unit block 1.

Specific sipe thickness d of each thin and thin sipe
Is not particularly limited, but is 0.1 to 1.0 m
It is preferably contained within the range of m. When a sipe having a sipe thickness d of less than 0.1 mm is used, the rigidity of the entire block becomes too large, and especially the water removal performance deteriorates. If a sipe having a sipe thickness d of more than 1.0 mm is used, the block rigidity becomes too low,
Abrasion resistance decreases. Therefore, even when each thin sipe is used, the sipe thickness d has an optimum value range of 0.
It is preferably within the range of 1 to 1.0 mm.

The thickness difference between the sipes is not particularly limited, but in order to improve the wear resistance performance and the snow and snow road performance at the same time, the thickness difference between the sipes that achieves the optimum balance is required. is there. The thickness difference between the sipe thickness d _n and the sipe thickness d _{n + 1} between the sipes having different sipe thicknesses,
When _expressed as a ratio in the relational expression of {1- (d _n / d _{n + 1} )} X100, it is desirable that the absolute value be 10 to 300%. When the thickness difference (ratio) is less than 10%, the difference in thickness between the sipes is small and the sipes effect is insufficient as much as the conventional case. On the other hand, when the thickness difference (ratio) exceeds 300%, the thickness difference between the sipes becomes too large, the rigidity of the block sandwiched between sipes becomes uneven, and the ground contact state becomes unstable. Is not preferable. Here, the absolute value of the thickness difference between the sipes is adopted because the thickness of the sipes d _n and d
_{This is because n + 1} can take any value of d _n > d _{n + 1} and d _n <d _{n + 1} . The use of the general formula of d _n and d _{n + 1} as the thickness of the sipe indicates that the thickness of the sipe is two or more.

The type of each sipe having a different thickness is not particularly limited, and as described above, two types or more may be used. When the sipe has two types of thickness, a thick sipe and a thin sipe, it is composed of two types of sipe: a thick sipe of 0.5 mm or more and 1.0 mm or less and a thin sipe of 0.1 mm or more and less than 0.5 mm. It is desirable to do. Furthermore, it is more preferable that one is a thick sipe of 0.5 mm to 0.7 mm and the other is a thin sipe of 0.2 mm to 0.4 mm.

In addition, 0.1 mm or more in one block
The number of thin sipes of less than 0.5 mm is preferably provided at a ratio of 70 to 90% with respect to the total number of all sipes in the range of 0.1 mm to 1.0 mm in one block. When the number of thin sipes is less than 70%, there is no great difference from the conventional technology, and there is no difference in the improvement of ice and snow road performance.
If it exceeds%, the above-mentioned water removal effect is deteriorated and the ice and snow road performance is deteriorated.

The depth h of each sipe having a different thickness is not particularly limited. However, preferably, in relation to the groove depth H of the lateral groove that divides the block in which the sipe is arranged,
It is desirable to be included in the range of 0.5H <h <H.
However, it is optimally used in the vicinity of h = 0.8H. h
If <0.5H, the rigidity becomes too large, and the ice and snow road performance due to sipes is not sufficient, and if h> H, the rigidity becomes too small, and similarly the siping effect becomes poor. Further, the interval between the sipes is not limited. As in the previous embodiment

The shape of the sipe is linear in the above embodiment as viewed from the surface of the block, but other shapes such as a sawtooth shape and a zigzag shape such as a corrugated shape are also applicable. The sipe having a zigzag shape has a longer sipe length than that of the straight type and has a sharp edge in all directions, which is more suitable for use as a studless tire. Further, the direction of the sipes extends parallel to the tire width direction, but any sipes extending in the tire width direction may have an oblique direction.

The sipe may be a double-open type in which both ends open in the groove at the block end, or a half-open type in which only one end is open, but the present invention is not limited to this.
A double-open type is preferable, but a half-open type is also used in consideration of drainage and the like. In addition, a sipe that is closed at both ends can also be included.

The sipes having different thicknesses in one block may be arranged alternately in the blocks, or the sipes having a large sipes may be arranged in the central area of the block and the sipes having a small sipes may be arranged in the end area of the block. However, it may be arranged irregularly. However, when they are arranged alternately in the block, it is preferable in that the rigidity balance in the block is good and uniform grounding is performed, and when the sipe with a large sipe thickness is arranged in the center region of the block and the sipe with a small sipe thickness is arranged in the block end region. Is also preferable in that the rigidity balance in the block is good and uniform grounding is achieved.

The sipes applied in the present invention can be applied to blocks in any area as long as it extends from the tire center area to the shoulder area.

[0019]

The present invention will be described in detail below with reference to preferred examples. The present invention is not limited to this embodiment.

In this embodiment, the tread patterns shown in FIGS. 4 and 5 are unified. In the figure, 4 is a block of the tire center area CA, 5 is a block of the intermediate area MA, and 6 is a block of the shoulder area SA. In addition, 7 is a tire tread surface, TC is a tire center, and e and e have shown the tire grounding edge. Reference numeral 8 is a circumferential groove, and 9 is a lateral groove that intersects with the circumferential groove.

The tire size is 185 / 70R14, and the type of sipe of this embodiment is composed of two types of sipe, a thick sipe and a thin sipe. Total number of thick sipes and thin sipes per block, sipes thickness d _n , d
The difference (ratio) between _{n + 1} and the sipe thickness is as shown in Table 1. In addition, in the present Examples 1 to 3, as shown in FIG. 4, one thick sipe is arranged in the center and five thin sipe are arranged on both sides in total, and in Example 4, as shown in FIG. In addition, one thick sipe is arranged in the center and seven thin sipes are arranged on both sides in total. In both cases, their intervals are equal. The depth h of the sipe in each of the blocks 4 and 5 of the tire center area CA and the tire middle area MA is set to 7.0 mm, and the depth h of the sipe of the block 6 in the shoulder area SA is set to 7.0 mm. ing.

Table 1 shows the results of each test of the snow and snow road performance and the wear resistance performance of tires having various sipe thicknesses. In Table 1, the tires of Comparative Examples 1 to 3 are
The tire has the same tread pattern as that of the tire of the above example except that the sipes have the same thickness.

The ice and snow road performance and the wear resistance performance are the same as those of ordinary passenger cars (1800 cc) equipped with these tires.
Then, the following test evaluated. The air filling rate and the test method conform to JATMA regulations.

(Ice test) The performance on ice was evaluated by the braking distance. That is, it is shown as the distance from 40 km / h until the brake is stopped at full brake. The evaluation results are calculated by calculating the reciprocal of the braking distance and then converting the reciprocal of the braking distance of the tire of Comparative Example 1 into a reference value of 100 for conversion into an index. The larger the value, the better the performance on ice.

(Compressed Snow Road Test) The compressed snow road performance was also evaluated by the braking distance. That is, it is shown as the distance from 30 km / h until the brake is stopped at full brake. The evaluation result was calculated by calculating the reciprocal of the braking distance, and then calculating the reciprocal of the braking distance of the tire of Comparative Example 1 as 1.
It is converted to an index and displayed as 00. The larger the value, the better the performance on the snow-covered road.

(General Road Test) DRY Steering Stability: It is shown by a driver's feeling evaluation during normal road running. Two drivers each test,
The average score of the two people is shown. The comparative example 1 is set to 100 and is shown by an index. The larger the number, the better. WET steering stability: It is shown by a driver's feeling evaluation while running on a normal road surface in which water is sprayed (a road surface simulated by a state after rain). The comparative example 1 is set to 100 and is shown by an index. The larger the number, the better. Abrasion resistance performance: A tire whose groove depth was measured in advance was mounted on an automobile, two passengers traveled, and while the mounting position was exchanged every 2000 km running, after running 12000 km, the groove depth was measured, The amount of wear is calculated from the difference in groove depth before and after running. The evaluation result is calculated by calculating the reciprocal of the wear amount and then converting and displaying the reciprocal of the wear amount of the conventional tire using an index as a reference value of 100. The larger the value, the better the wear resistance. It should be noted that the tire air pressure is the air pressure specified by the vehicle. Block rigidity: According to FEM analysis method (finite element analysis method). The end is moved by 1 mm, and the amount of displacement is measured.
The value of the tire of the present invention is converted into an index and displayed with the conventional tire as a reference value of 100. The higher the value, the better.

[0027]

[Table 1]

As shown in Table 1, in the tires of Comparative Examples 1 to 3 in which the sipes have the same thickness, in the case of Comparative Example 2 in which the sipes have a small thickness, the block rigidity is increased and thus the wear resistance is improved, but the snow and snow are improved. The road performance is deteriorated, and in the case of Comparative Example 3 in which the sipe thickness is increased, the block rigidity is decreased and the wear resistance performance is decreased. On the other hand, in the case of the example tires of the present invention having different sipe thicknesses, the wear resistance and the snow and snow road performance are simultaneously improved, and the steering stability is good. In particular, the thickness difference between the sipe thickness d _n and the sipe thickness d _{n + 1} between the sipes is {1- (d _n / d _{n + 1} )} X1
In the relational expression of 00, good ice and snow road performance is secured in the range of 10 to 300%. In Comparative Example 5, the ground contact was uneven, which was not preferable. Although the number of sipes is increasing in the third embodiment,
Since the ratio of the thin sipes is set to 70% or more so that the rigidity of the block does not decrease, the effect of the present invention is effectively exhibited. In addition, the tires of this example all had good pattern effects of water removal, adhesion, and scratching sipe. In particular, Examples 2 and 3 were excellent in scratching effect, and Example 4 was optimum in terms of water removal, adhesion and scratching.

[0029]

EFFECTS OF THE INVENTION The present invention forms a plurality of types of sipes that extend in the tire width direction and have different sipe thicknesses in one block on the tire tread surface, so that the block rigidity is maintained and ice snow is a trade off. It is possible to improve road performance and wear resistance at the same time.

[Brief description of drawings]

FIG. 1 is a model diagram of a unit block showing an embodiment of the present invention.

FIG. 2 is a model diagram of a unit block showing the other embodiment.

FIG. 3 is a model diagram of a unit block showing an example of a conventional tire.

FIG. 4 is a schematic view of a tread pattern showing an embodiment of the present invention.

FIG. 5 is a schematic view of a tread pattern showing the other embodiment.

[Explanation of symbols]

1 block 2 thin sipes 3 thick sipes 4 blocks 5 blocks 6 blocks 7 tire tread surface 8 circumferential grooves 9 lateral grooves d Sipe thickness h Sipe depth e Tire ground contact end CA tire center area MA middle area SA shoulder area

Claims (6)

(57) [Claims] 1. A pneumatic tire having a tire tread surface provided with a block divided by a plurality of circumferential grooves and lateral grooves intersecting with the circumferential grooves, wherein the tire tread surface has a tire within one block. The sipe that extends in the width direction and has a different sipe thickness is provided with two types of sipe, that is, a thick sipe of 0.5 mm or more and 1.0 mm or less and a thin sipe of 0.1 mm or more and less than 0.5 mm. A pneumatic tire characterized in that thin sipes are provided in a proportion of 70 to 90% with respect to the total number of all sipes per block. 2. A plurality of circumferential grooves and intersections of these circumferential grooves.
The tire tread surface is divided into blocks that are divided by lateral grooves.
In a pneumatic tire prepared for
The surface extends in the tire width direction within one block and
Equipped with blocks with multiple types of sipes with different thickness
The sipe with a thick sipe is supported in the center area of the block.
A thin sipe is installed in the block end area.
A pneumatic tire characterized in that 3. The sipes have a size of 0.5 mm or more and 1.0 mm or less.
Thick lower sipe and less than 0.1mm ~ less than 0.5mm
The thin sipe is composed of two types of sipes.
Pneumatic tire described. 4. The thin sipe according to claim 3 is one block.
70 to 90% of the total number of all sipes per
The pneumatic tire according to claim 3, which is provided. 5. The depth h of the sipe is such that the sipe is located.
In relation to the groove depth H of the lateral groove that divides the block,
The range of 0.5H <h <H is included.
The pneumatic tire according to any one. 6. Two types of sipes with different sipes thickness are
Either of the claim 2 or 3, wherein the locks are arranged alternately.
Pneumatic tire described in Crab.