JP3208417B2 - 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, and more particularly, to a pneumatic tire having a block pattern and a sipe formed in the block.

[0002]

2. Description of the Related Art As a tire used for a vehicle traveling on an icy road, a pneumatic tire has been proposed in which a block is provided with a sipe and the running performance on an icy road is improved by the edge effect of the sipe.

As shown in FIG. 9, a pair of sipes 102 are arranged in parallel with each other in the tire circumferential direction (arrow A direction in FIG. 9) and extend in the tire width direction (front-back direction in FIG. 9).
Pneumatic tire 1 provided with block 104 formed with
At 00, when the block 104 is deformed by receiving a frictional force in the tangential direction of the tire outer periphery from the road surface, one of the pair of sipes 102 is closed and the other is opened, and the driving performance and the braking performance are improved by the edge effect.

[0004]

However, the sipe 10
In the case of No. 2, since the groove width t is narrow, stress tends to concentrate on the bottom 102A when the sipe 102 is opened, and cracks tend to occur from the bottom 102A.

[0005] In order to solve the above-mentioned disadvantage, FIG.
As shown in the figure, the enlarged portion 10 having a circular cross section is formed on the bottom portion 102A.
6 may be provided, but in this method, if the interval L between the enlarged portions 106 becomes too narrow, FIG.
As shown in (B), the blade 1 of the vulcanization mold 108
10, the rigidity of the narrow region 104A between the sipe 102 becomes low, and the shear deformation amount when receiving the longitudinal force F during traveling increases. There is also a problem that a crack is easily generated from the bottom 102A.

In view of the above facts, the present invention prevents the occurrence of cracks from the bottom of a sipe when a pair of sipes are provided in a block of a pneumatic tire and, when removing the sipe from the vulcanization mold, inserts a sipe into the vulcanization mold. It is an object of the present invention to provide a pneumatic tire capable of preventing rubber from remaining therebetween.

[0007]

According to the first aspect of the present invention,
An enlarged portion is formed at the bottom and a narrow region sandwiched by a pair of sipes substantially extending in the tire width direction, and a wide region located on both sides of the narrow region via the sipe, Pneumatic tire having a block having a relationship between the tire circumferential average length TS in the narrow region and the tire circumferential average length TL in the wide region in a relationship of 0.1 ≦ TS / TL ≦ 0.8. Wherein said enlargement of said two sipes
Average distance L between the parts and average circumferential length of the narrow region in the tire circumferential direction
TS and 0.7 ≦ L / TS ≦ 1.5.
The enlarged portion is convex in a direction away from each other, and
It is not convex in the direction approaching each other.
are doing.

[0008]

[0009]

According to the first aspect of the present invention, when the pneumatic tire comes into contact with the ground and the block receives a frictional force in the tangential direction of the tire outer periphery by driving or braking, the block is deformed but is sandwiched by the sipes. The relationship between the tire circumferential average length TS of the narrow region of the block and the tire circumferential average length TL of the wide region of the block located on both sides of the narrow region via the sipe is 0.1 ≦ TS / TL ≦ Since it is set to 0.8, there is a difference in rigidity between the narrow region and the wide region, and the deformation of the narrow region is larger than that of the wide region. For this reason, in the block subjected to the frictional force, one of the two sipes is closed and the other sipes are opened, and the running performance is enhanced by the edge effect of the tread side corner of the narrow area on the opened sipe side. (Driving performance and braking performance) are improved.

Further, in the pneumatic tire of the present invention, since the enlarged portion is provided at the bottom of the sipe, the stress applied to the bottom when the sipe is opened is dispersed by the enlarged portion,
The generation of cracks from the bottom is prevented. In addition, the tire circumferential distance L between the enlarged portions of the two sipes and the tire circumferential average length TS of the narrow region are set to 0.7 ≦ L / T.
By setting the relationship of S ≦ 1.5, a decrease in rigidity at the root portion of the narrow region sandwiched between the two sipes of the block is suppressed, and the air from the vulcanization mold for molding the pneumatic tire is reduced. When the tire containing the tire is taken out, the narrow region is prevented from remaining between the vulcanized mold blades forming the sipe.

If the ratio L / TS of the tire circumferential direction distance L between the enlarged portions of the two sipes to the tire circumferential average length TS of the narrow region is less than 0.7, the narrow region When the pneumatic tire is removed from the vulcanization mold, the narrow region may be left between the blades forming the sipe when the pneumatic tire is removed from the vulcanization mold. Since the shear force is reduced due to the longitudinal force during traveling, cracks may be generated from the bottom of the sipe, which is not preferable. If the ratio L / TS is more than 1.5, the rigidity of the wide region is reduced, and the inclination of the blade of the vulcanization mold that forms the sipe increases, making it difficult to remove the pneumatic tire from the vulcanization mold. Is not preferred.

The enlarged portion is convex in a direction away from each other.
But are convex in the direction approaching each other.
Because there is no narrow region between the sipes, the root portion is not constricted. For this reason, when removing the pneumatic tire from the vulcanization mold, the narrow region of the block is smoothly released from the vulcanization mold.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS.

The pneumatic tire 10 to which the present invention is applied has a block pattern, and the block 12 has a substantially prismatic shape. The dimension T of the block 12 in the tire circumferential direction (the direction of arrow A in FIG. 1) is preferably 15 mm ≦ T ≦
40 mm, more preferably 20 mm ≦ T ≦ 35 mm.

Here, when the tire circumferential dimension T of the block 12 exceeds 40 mm, the contact effect decreases with an increase in the tire circumferential direction length of the block 12, so that an edge effect is expected. It is not preferable because the driving performance and the braking performance decrease. On the other hand, if the tire circumferential dimension T is less than 15 mm, the rigidity of the block 12 becomes too small, so that it is difficult to expect the edge effect of the block 12, and the driving performance and the braking performance are undesirably reduced. In this embodiment, the dimension W of the block 12 in the tire width direction (the front-rear direction in FIG. 1) is set to 30 mm.

The block 12 includes a pair of parallel sipe 1 extending linearly in the tire width direction.
4 (The sipe referred to herein means a groove having a groove width of preferably 1 mm or less, more preferably 0.6 mm or less.)
Are formed. In this embodiment, sipe 1
The groove width of No. 4 is set to 0.5 mm.

Both longitudinal ends of the sipe 14 reach the side wall 12A of the block 12 on the tire width direction side, and the block 12 is divided into three regions in the tire circumferential direction by the sipe 14. A region sandwiched between the pair of sipes 14 is a narrow region 16, and a region adjacent to the narrow region 16 on both sides in the tire circumferential direction is a wide region 18.

In the bottom portion 14A of the sipe 14, the center of the radius of curvature is located closer to the wide area 18 than the extension line of the sipe 14, and the cross section of the sipe 14 at right angles in the longitudinal direction is enlarged in a circular shape. 15 are provided. In addition, enlargement section 1
5 is wider than the sipe 14 and has a radius of curvature R
Is preferably in the range of 0.5 mm to 2 mm. The radius of curvature R of the enlarged portion 15 in this embodiment is set to 1.5 mm.

The ratio TS / TL between the width TS of the narrow region 16 and the width TL of the wide region 18 is 0.1 ≦ TS / T.
L ≦ 0.8, preferably 0.2 ≦ TS / T
L ≦ 0.5. In addition, the block 1 of the present embodiment
2. The tire circumferential dimension TL of the wide area 18 is 14 mm.
The width TS of the narrow region 16 in the tire circumferential direction is set to 5 mm, and the ratio TS / TL to the width TL of the wide region 18 is about 0.36.

Therefore, the rigidity of the narrow region 16 is smaller than the rigidity of the wide regions 18 on both sides. For this reason, as shown in FIG. 2, when the block 12 comes into contact with the road surface 20 during driving or braking and a frictional force (direction of arrow F in FIG. 2) acts on the block 12 in the tire outer circumferential direction, the wide area 1
8 is small, and the deformation of the narrow region 16 is large.
Thereby, the sipe 14 in the direction of arrow F of the two sipes 14 is closed, the sipe 14 in the direction opposite to the direction of arrow F is opened, and the corner 16B of the narrow region 16 on the side of the tread surface 16A.
The performance on ice is improved by the edge effect.

Further, since the enlarged portion 15 is provided at the bottom portion 14A of the sipe 14, the stress applied to the bottom portion 14A when the sipe 14 is opened is dispersed by the enlarged portion 15, and cracks are generated from the bottom portion 14A. Is effectively prevented.

If the ratio TS / TL of the width TS of the narrow region 16 to the width TL of the wide region 18 exceeds 0.8, the difference in rigidity between the narrow region 16 and the wide region 18 is reduced, and during braking and When driven, the sipe 14 becomes difficult to open, and the edge effect cannot be expected. When the sipe 14 is less than 0.1, the rigidity of the narrow region 16 is excessively reduced, and the durability of the narrow region 16 is undesirably reduced.

The ratio L / TS of the shortest dimension L between the bottoms 14A of the pair of sipes 14 and the width TS of the narrow region 16
Is set to have a relationship of 0.7 ≦ L / TS ≦ 1.5, and since the base portion 16B is not constricted by the enlarged portion 15, even if the enlarged portion 15 is provided on the bottom portion 14A of the sipe 14, the narrow region The strength of the base portion 16B of the base 16 does not decrease, and the narrow region 16 does not remain in the vulcanization mold when the pneumatic tire 10 is taken out from the vulcanization mold (not shown).

If the ratio L / TS of the shortest dimension L between the bottoms 14A and the width TS of the narrow region 16 is less than 0.7, the strength of the base portion 16B of the narrow region 16 decreases. When removing the pneumatic tire 10 from the vulcanization mold, the narrow region 1 between the blades forming the sipe 14.
6 may be left behind, and the rigidity of the narrow region 16 may be reduced to increase the shear deformation due to the longitudinal force during traveling, which may cause cracks from the bottom 14A, which is not preferable. When the ratio L / TS exceeds 1.5, the rigidity of the wide area 18 is reduced and the blade of the vulcanization mold for forming the sipe 14 is steeply inclined. It is not preferable because it is difficult to take it out.

Next, a second embodiment of the present invention will be described with reference to FIG. The same components as those of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The sipes 14 of the second embodiment are inclined so as to be separated from each other toward the bottom 14A, and the enlarged portion 15 is formed in a circular shape. Also in this embodiment, the shortest dimension L between the bottoms 14A of the pair of sipes 14 is set.
And the ratio L / TS of the width TS of the narrow region 16 is 0.7 ≦
Since L / TS ≦ 1.5, the strength of the base portion 16B of the narrow region 16 does not decrease as in the first embodiment, and the narrow region 16 remains in the vulcanization mold. There is no. When the sipes 14 are opened, the bottom 14A
Is distributed by the enlarged portion 15, so that the occurrence of cracks from the bottom portion 14 </ b> A is effectively prevented.

Next, a third embodiment of the present invention will be described with reference to FIG. The same components as those of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The pair of sipes 14 of this embodiment are provided in parallel with each other, and the enlarged portion 15 has a substantially water-drop shape which swells toward the wide area 16.

In this embodiment, since the ratio L / TS of the shortest dimension L between the bottoms 14A of the pair of sipes 14 and the width TS of the narrow region 16 is set to 1, the first embodiment differs from the first embodiment. Similarly, the strength of the base portion 16B of the narrow region 16 does not decrease, and the narrow region 16 does not remain in the vulcanization mold. Further, since the enlarged portion 15 is formed in a substantially water-drop shape, a vulcanization mold type blade (not shown) forming the enlarged portion 15 is provided on the pneumatic tire 10 of the first embodiment and the second embodiment. Extraction is further facilitated in comparison. Further, similarly to the first embodiment, since the stress applied to the bottom 14A when the sipe 14 is opened is dispersed by the enlarged portion 15, the occurrence of cracks from the bottom 14A is effectively prevented.

Next, a fourth embodiment of the present invention will be described with reference to FIG. The same components as those of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The sipes 14 of the present embodiment are inclined so as to move away from each other toward the bottom 14A.
The enlarged portion 15 has a substantially water-drop shape that swells toward the wide area 16.

Also in this embodiment, the ratio L / TS of the shortest dimension L between the bottoms 14A of the pair of sipes 14 and the width TS of the narrow region 16 is set to 0.7 ≦ L / TS ≦ 1.5. As in the first embodiment, the strength of the base portion 16B of the narrow region 16 is not reduced, and the narrow region 16
Easily escapes from the vulcanization mold and does not remain in the vulcanization mold. Moreover, since the stress applied to the bottom portion 14A when the sipe 14 is opened is dispersed by the enlarged portion 15, the occurrence of cracks from the bottom portion 14A is effectively prevented.

Next, a fifth embodiment of the present invention will be described with reference to FIG. The same components as those of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The sipes 14 of the present embodiment are inclined so as to be separated from each other as approaching the bottom 14A.
Further, the sipe 14 has a tapered shape in which the groove width is increased toward the bottom 14A. Note that the enlarged portion 15 is formed in a semicircular shape, and the pair of sipes 14 is formed.
Of the sipe 14 is regulated such that the ratio L / TS of the shortest dimension L between the bottom portions 14A of the first and second portions 14A to the width TS of the narrow region 16 falls within the range of 0.7 ≦ L / TS ≦ 1.5. ing.

Also in this embodiment, the ratio L / TS of the shortest dimension L between the bottoms 14A of the pair of sipes 14 and the width TS of the narrow region 16 is in the range of 0.7 ≦ L / TS ≦ 1.5. , The narrow region 16 is set in the same manner as in the first embodiment.
The narrow region 16 is easily pulled out of the vulcanization mold and does not remain in the vulcanization mold without causing a decrease in the strength of the base portion 16B. Moreover, since the stress applied to the bottom portion 14A when the sipe 14 is opened is dispersed by the enlarged portion 15, the occurrence of cracks from the bottom portion 14A is effectively prevented.

In the first to fifth embodiments, the block 12 has a rectangular shape in plan view of the tread. However, the present invention is not limited to this, and as shown in FIG. The dimension may be shorter than the longitudinal dimension of the wide area 18, and may be trapezoidal as shown in FIG. 8, and the planar shape of the block 12 is not limited thereto.

In each of the above embodiments, one set of a pair of sipes is provided for one block. However, the present invention is not limited to this, and two or more sets of a pair of sipes may be provided for one block. Good. (Test Example) Table 1 below shows a conventional product A (a pneumatic tire having a block shape shown in FIG. 9), a conventional product B (a pneumatic tire having a block shape shown in FIG. 10), and a comparative example product (FIG. 3). Pneumatic tire having a block shape shown in
Product A of the present invention (pneumatic tire having a block shape shown in FIG. 3 of the second embodiment) and Product B of the present invention (FIG. 3 of the second embodiment)
) And a product C of the present invention (the pneumatic tire having the block shape shown in FIG. 1 of the first embodiment) are filled with prescribed internal pressures, respectively, and these pneumatic tires are constantly loaded. FIG. 3 shows the results of measuring the distance traveled until the cracks occurred at the bottom of the sipe by actually mounting the 10-ton truck on the driving wheels of the 10-ton truck.

Table 2 shows that the rubber remaining between the blades (provided in the vulcanization mold) forming the sipes when the pneumatic tire used in Table 1 was taken out of the vulcanization mold. And the percentage of rubber remaining are indicated.

The test tires all had a size of 10.0.
0R20, and the same number of caramel blocks (624) are provided.

[0040]

[Table 1]

[0041]

[Table 2]

From the test results shown in Table 1, it is clear that the pneumatic tire 10 of the present invention prevents cracks from being generated from the bottom 14A of the sipe 14, and the test results shown in Table 2 show that the pneumatic tire 10 of the present invention has no cracks. When the pneumatic tire 10 was taken out of the vulcanization mold, it became clear that the narrow region 16 did not remain in the vulcanization mold.

[0043]

Since the pneumatic tire of the present invention has the above-described structure, it is possible to prevent the occurrence of cracks from the bottom of the sipe and to prevent the rubber between the sipe from remaining in the vulcanization mold when the pneumatic tire is taken out from the vulcanization mold. Has an excellent effect.

[Brief description of the drawings]

FIG. 1 is a side view of a block of a pneumatic radial tire according to a first embodiment of the present invention as viewed from a tire width direction.

FIG. 2 is a side view of the pneumatic radial tire according to the first embodiment of the present invention as viewed from the tire width direction, showing a state where the block is deformed by receiving a frictional force.

FIG. 3 is a side view of a block of a pneumatic radial tire according to a second embodiment of the present invention as viewed from the tire width direction.

FIG. 4 is a side view of a block of a pneumatic radial tire according to a third embodiment of the present invention as viewed from the tire width direction.

FIG. 5 is a side view of a block of a pneumatic radial tire according to a fourth embodiment of the present invention as viewed from the tire width direction.

FIG. 6 is a side view of a block of a pneumatic radial tire according to a fourth embodiment of the present invention as viewed from the tire width direction.

FIG. 7 is a development view of a tread showing a block of a pneumatic radial tire according to another embodiment of the present invention.

FIG. 8 is a development view of a tread showing blocks of a pneumatic radial tire according to another embodiment of the present invention.

FIG. 9 is a side view of a block of a conventional pneumatic radial tire as viewed from the tire width direction.

FIG. 10A is a side view of a block of a pneumatic radial tire according to a conventional example viewed from a tire width direction;
(B) is a cross-sectional view of the block and the vulcanization mold viewed from the tire width direction, showing a state in which the block of the pneumatic radial tire according to the conventional example has come out of the vulcanization mold.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Pneumatic tire 12 Block 14 Sipe 14A Bottom part 15 Enlarged part 16 Narrow area 18 Wide area

Claims (1)

(57) [Claims] An enlarged portion is formed at a bottom portion, and is located on both sides of a narrow region sandwiched between a pair of sipes extending substantially in the tire width direction and via the sipes. A block having a wide area, wherein the average tire circumferential length TS of the narrow area and the average circumferential length TL of the wide area are 0.1 ≦ TS / TL ≦ 0.8.
The average distance L between the enlarged portions of the two sipes and the width.
The average circumferential length TS of the narrow region in the tire circumferential direction is 0.7 ≦ L / T.
S ≦ 1.5, the enlarged portions are convex in the direction away from each other,
Note that they are not convex in the direction approaching each other.
Pneumatic tires to be featured.