JP2000247114A - Pneumatic tire and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire improved in steering stability by improving the block rigidity. SOLUTION: A sipe 22 opened on both sides is formed on a block 18. The block 18 is divided into small blocks 18A, 18B. A connecting member 26 is inserted to the recessed part 24 formed on the small blocks 18A, 18B and fixed by an adhesive, whereby the small blocks 18A, 18B are mutually connected. According to this, the rigidity of the small blocks 18A, 18B in the initial stage of wear can be improved to improve the steering stability.

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 improved handling stability by connecting small blocks divided by a sipe, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a pneumatic tire is provided with a sipe in a block formed on a tread surface to improve a driving force / braking force on a wet road surface or an ice-snow road surface by increasing an edge component and improving drainage. ing.

[0003]

However, in the early stage of use of the pneumatic tire, since the block height (height from the groove bottom to the tread) is high, the rigidity of the small block divided by the sipe is low, and the steering is difficult. There was a possibility that the stability was not sufficiently secured. In particular, in the case of studless tires in which a large number of sipes are placed in each block, it is required to improve the rigidity of the block at the beginning of use in order to improve steering stability.

[0004] The present invention has been made to solve the above problems, and an object of the present invention is to provide a pneumatic tire with improved steering stability by improving the block rigidity at the beginning of use, and a method of manufacturing the same.

[0005]

In order to achieve the above object, according to the present invention, a tread surface is defined by a main groove extending in a tire circumferential direction and a lug groove intersecting the main groove. A pneumatic tire having a plurality of block-shaped land portions, and a sipe opened in the groove provided in the block-shaped land portion, wherein a connecting member for connecting small blocks divided by the sipe is provided. It is characterized by having.

The operation of the first aspect of the present invention will be described.

In the pneumatic tire according to the present invention, among the small blocks divided by the sipe, small blocks adjacent to each other across the sipe are connected by a connecting member. As a result, the rigidity of the small block is improved, and especially in the early stage of use when the block height is sufficiently high, the steering stability is improved.

According to a second aspect of the present invention, in the first aspect of the invention, the connecting member is a rubber composition.

The operation of the second aspect of the present invention will be described.

[0010] By forming the connecting member from a rubber composition, preferably the same composition as the block-shaped land portion, the small block (block-shaped land portion) and the connecting member are similarly worn. Therefore, the connecting member does not protrude from the tread of the block-shaped land portion with the abrasion of the pneumatic tire, and the steering stability, uneven wear and the like are not negatively affected.

According to a third aspect of the present invention, in the first or the second aspect of the present invention, the connecting member is disposed on a tread side of the block-shaped land portion.

The operation of the invention will be described.

Since the connecting member is arranged on the tread side of the block-shaped land portion, the connecting member exists in the initial stage of wear, and disappears after the middle stage of wear due to wear. That is, when the height of the small block is large and the rigidity is low, the rigidity of the small block is secured by the connecting member, and after the connecting member disappears due to wear, the rigidity of the small block is sufficiently reduced because the block height is reduced. Secured. Further, in a state where the abrasion has progressed, the connecting member disappears on the sipe, and the opening area of the sipe exposed on the tread surface increases. As a result, the edge component increases and the drainage of the sipe improves.

According to a fourth aspect of the present invention, there is provided the invention as set forth in any one of the first to third aspects, wherein the connecting member is disposed on a small block at a position above the sipe. The width of the sipe in the longitudinal direction is larger than that of the portion arranged in the sipe.

The operation of the invention will be described.

Since the connecting member has a wider portion disposed on the small block than a portion disposed on the sipe, the width of the connecting member disposed on the sipe can be suppressed while ensuring the strength of the connecting member. As a result, the sipe area exposed on the tread is sufficiently ensured, and the edge component and drainage can be sufficiently ensured despite the provision of the connecting member.

According to a fifth aspect of the present invention, in order to achieve the above-mentioned object, in the first aspect of the present invention, the connecting member is provided with one of the portions opening to the tread surface of the sipe.
It is characterized by covering 0% to 40%.

The operation of the invention will be described.

If the ratio of the connecting member to the area where the sipe opens on the tread is less than 10%, the connecting member has insufficient strength to connect the small blocks, and the connecting member is severely cut by repeated deformation of the small block. Would.
On the other hand, when the ratio exceeds 40%, the connecting member covers the opening of the sipe too much, and the edge effect and drainage of the sipe are greatly reduced, and steering stability is impaired. Therefore,
By setting the ratio to 10% to 40%, both the strength of the connecting member and the edge effect of the sipe can be satisfactorily compatible.

In order to achieve the above object, according to the present invention, a plurality of block-shaped land portions defined by a circumferential groove extending in a tire circumferential direction and a lug groove intersecting the circumferential groove are provided. A method for manufacturing a pneumatic tire, wherein a sipe is provided on the block-shaped land portion, wherein at least one end of the sipe having an opening in the groove is provided on the block-shaped land portion, and both small sides sandwiching the sipe are provided. A step of vulcanizing and forming a tire having concave portions opposed to each other in the block, and a step of connecting the two small blocks to each other by bonding a connecting member to the concave portions of the two small blocks. .

The operation of the invention will be described.

Pneumatic tires provided with concave portions facing each other in small blocks sandwiching the sipe are vulcanized and molded, and both ends of the connecting member are inserted into concave portions of both adjacent small blocks.
Paste with adhesive. As a result, adjacent small blocks are connected to each other. Therefore, unlike the case of integrally molding including the connecting member, it is not necessary to use a mold having a complicated shape at the time of vulcanization molding, and the production is easy.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A pneumatic tire according to a first embodiment of the present invention and a method for manufacturing the same will be described in detail. Hereinafter, the present embodiment will be described with reference to FIGS.

As shown in FIG. 2, the pneumatic tire 10
Is provided with a cylindrical tread 12 straddling a pair of left and right sidewalls (not shown). On tread 12,
A plurality of main grooves 14 formed along the tire circumferential direction (arrow P direction) and a plurality of lug grooves 16 formed along the tire width direction (arrow W direction) are formed. A plurality of blocks 18 are defined by the main groove 14 and the lug groove 16. In FIG. 2, a sipe 22 and a connecting member 26 which will be described later are omitted.

As shown in FIG. 1, a sipe 22 extending in the tire width direction is formed in these blocks 18. The sipe 22 is a double-sided open sipe having both ends opened to the block end surface. Therefore, block 18
Is divided into small blocks 18A and 18B by a sipe 22. In each of the small blocks 18A and 18B, a T-shaped concave portion 24 is formed in an opposite direction at a position facing the sipe 22 of the tread surface 20 so as to face each other. The recess 24 has a narrow portion 24A having a width W1 facing the sipe 22 and a width W2 formed on the inner side of the narrow portion 24A.
And a wide portion 24B. Here, the widths W1 and W2 are
It refers to the length of the sipe 22 in the longitudinal direction (tire width direction).

The recesses 24, 2 of the small blocks 18A, 18B
4, the connecting member 26 is inserted. The connecting member 26 is an I-shaped member having a thickness H formed of the same composition as that of the block 18, and has a base 26A having a width W2 formed at both ends.
And a connecting portion 26B having a width W1 formed between the base portions 26A. Therefore, the small blocks 18A and 18B are connected by inserting the connecting member 26 into the concave portions 24 of both the adjacent small blocks 18A and 18B and fixing them with an adhesive. Since the thickness H of the connecting member 26 and the depth of the concave portion 24 are the same, the inserted connecting member 26 does not protrude from the tread surface 20. In the present embodiment, assuming that the depth of the sipe 22 is D, the connecting member 26
Has a thickness H of 0.3D.

The pneumatic tire 10 manufactured as described above
The operation of will be described.

The following effects can be obtained by mounting the pneumatic tire 10 on an automobile and running.

In the initial stage of wear, since the height of the block 18 is high, the rigidity of the small blocks 18A and 18B is insufficient. However, the small block 1 is
Since 8A and 18B are connected to each other, rigidity is improved,
The steering stability of the pneumatic tire 10 is improved. Further, since the connecting member 26 is formed of the same composition as the block 18, the connecting member 26 wears down similarly to the small blocks 18A and 18B. Therefore, only the connecting member 26 protrudes from the tread surface 20 and does not affect the steering stability.

After the middle period of wear, the height of the block 18 decreases. At this time, the connecting member 26 having a thickness H of only 30% (0.3D) from the tread surface 20 with respect to the sipe depth D is worn. Or the connecting portion 26B is disconnected before the disappearance. However, small block 18
Since the height of A and 18B is low, the block rigidity is sufficiently ensured. In addition, after the connection member 26 disappears, the area of the sipe 22 opening to the tread surface 20 increases, the edge component of the sipe 22 increases, and the drainage property also improves, so that good steering stability can be secured.

Next, a pneumatic tire according to a second embodiment of the present invention and a method for manufacturing the same will be described. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

The pneumatic tire 10 according to the present embodiment is
This is substantially the same as the tread pattern shown in FIG. However, each block 18 has a rectangular shape long in the tire circumferential direction in plan view, and each block 18 is provided with five sipes 22 at predetermined intervals (see FIG. 4).

That is, the block 18 is divided into six small blocks 18A to 18F by the sipes 22. A concave portion 24 is formed in each of the small blocks 18A to 18F in the same manner as in the first embodiment, and the adjacent small block 18A is formed.
The connecting member 26 is inserted and bonded between 〜 and 18F. FIG.
As shown in the figure, between small blocks 18A-18B, 18C-
Two connecting members 26 connect between 18D and 18E-18F, and one connecting member 26 connects between small blocks 18B and 18C and between 18D and 18E. That is, the two small blocks 18A to 18F are alternately connected by one connecting member 26.

By configuring the pneumatic tire 10 in this manner, the block rigidity of the small blocks 18A to 18F in the initial stage of wear is improved as in the first embodiment. Since the low stiffness due to the provision of the sipe 22 can be compensated for, the steering stability and the braking performance at the initial stage of wear are significantly improved. In addition, after the middle period of wear when the rigidity of the small blocks 18A to 18F is improved, since the connecting member 26 disappears due to wear, the area exposed on the tread surface 20 of the sipe 22 increases, the edge component increases, and the drainage property increases. improves.

Further, as a pneumatic tire according to a third embodiment of the present invention and a method of manufacturing the same, an improved example of the pneumatic tire according to the second embodiment will be described. The same components as those in the second embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the pneumatic tire 10 of the present embodiment, the connecting member 26 (see the hatched portion in FIG. 5) arranged in the block 18 is integrated.

That is, each of the small blocks 18A to 18F has a recess 24C penetrating from one end face to the other end face.
And a narrow portion 24 </ b> A communicating with the sipe 22, in which the integrated connecting member 26 is integrated with the block 1.
8, one is inserted and fixed with an adhesive.

By configuring the pneumatic tire 10 in this manner, the same operation and effect as those of the second embodiment are exhibited, and the operation of bonding and fixing the connecting member 26 to the concave portion 24 in the manufacturing process is simplified, and the productivity is improved. Is improved.
Moreover, since the width W1 of the connecting portion 26B of the connecting member 26 disposed on the sipe 22 is not changed, the edge effect and drainage are not reduced as compared with the second embodiment. [Test Example] In order to confirm the action of the present invention, a steering stability test was performed.

First, in the first test, the example used was
The comparative example tire has a tread pattern shown in FIG. 2 and a block size of (length) × (width) × (height) = 20 mm × 2.
0 mm × 8 mm, one sipe 22 in the block 18
(Sipe depth D = 7 mm). The tire of the example is a tire in which the connecting member 26 is bonded to the concave portion 24, and the tire of the comparative example has no connecting member (no concave portion). Here, the connecting portion 26 of the connecting member 26
The width W1 of B is 3 mm, the width W2 of the base 26A is 5 mm, and the thickness H is 2 mm.

The tire is mounted on a vehicle, and a skilled test driver performs a test course (dry road surface, wet road surface).
By driving the vehicle, the feeling of dry steering stability (hereinafter referred to as dry steering) and wet steering stability (hereinafter referred to as wet steering) was evaluated on a scale of 10 out of 10 points. Here, the wet road surface refers to a road surface having a water depth of 20 mm. Table 1 shows the results.

[0041]

[Table 1]

As described above, in both dry operation and wet operation, the example tire in which the small blocks 18A and 18B were connected by the connecting member 26 exceeded the conventional tire. This is because the small blocks 18A, 18
It is considered that the rigidity was improved by connecting B. Although a wear test was also performed, the connection member 2
6 and the small blocks 18A and 18B were both abraded cleanly. It is considered that since the connection member 26 disappears due to wear after the middle period of wear, the straight sipe is exposed on the tread surface 20, and the edge effect and the drainage property are sufficiently exhibited.

Next, in a second test, the operation and effect of the present invention were examined for studless tires. Both the example tire and the comparative example tire have a tread pattern shown in FIG. 2 and a block size of (length) × (width) × (height) = 30 mm × 20 m.
As shown in FIG. 4, five sipe (sipe depth D = 7 mm) were formed as shown in FIG. The tire of the example is a tire in which the connecting member 26 is bonded to the concave portion 24, and the tire of the comparative example has no connecting member (no concave portion). Here, the width W1 of the connecting portion 26B of the connecting member 26 is 3
mm, the width W2 of the base 26A is 5 mm, and the thickness H is 2 mm.

The tire was mounted on a vehicle, and a skilled test driver traveled on a test course (dry road surface, icy road surface) to evaluate the steering stability on a scale of 10 points. In addition, the vehicle travels on an icy road at a speed of 20 km / h and measures the braking distance until it stops with full brakes.
The reciprocal was evaluated as braking performance on ice. The brake performance on ice was evaluated by an index with the conventional tire set to 100. Table 2 shows the results. A large index indicates good.

[0045]

[Table 2]

As described above, also in this test, the connecting member 2
6, the rigidity is improved by connecting the small blocks 18A to 18F, and the on-ice driving performance is improved.
The braking performance on ice is improved. In particular, the improvement in braking performance on ice and the like is remarkable. This is because pneumatic tires (studless tires) in which a large number of sipes 22 are provided in the block 18, so that the small blocks 18 A to 18 F are connected.
It is considered that the rigidity of the steel sheet was significantly improved.

Further, in the above embodiment, the connecting member 26
The relationship between the operation on ice and the durability with respect to the width W1 of the connecting portion 26B was examined. That is, in the configuration of the block 18 and the connecting member 26 shown in FIG. 4, the area ratio of the eight connecting members 26 (connecting portions 26B) covering the five sipes 22 (((8 × W2) / (5 × 20 mm) ) × 100
%) And the on-ice driving performance and durability were examined.
Here, the on-ice driving performance was evaluated by feeling (the index was large) with the case where the area ratio was 50% as a reference (0.0). The durability was determined based on whether or not the connecting portion 26B of the connecting member 26 was cut after traveling a predetermined distance.
Table 3 shows the test results.

[0048]

[Table 3]

As can be seen from the test results, the connecting member 26
If the width W1 of the connecting portion 26B is too small, it lacks durability,
The connecting portion 26B is cut off. Also, the connecting portion 26B
If the width W1 is large, the area of the sipe 22 exposed on the tread surface 20 is reduced, the edge component of the pneumatic tire is significantly reduced, and the operation on ice is reduced. Therefore, Sipe 2
2 is 10% to 40%
Is preferred.

A fourth test similar to the third test was performed on the pneumatic tire according to the third embodiment. The block size and the like are the same as in the third test. Here, the connecting member 26 has five patterns shown in FIGS. 5 to 9 (the width W1 of the connecting portion 26B is 1.5 mm, 2.0 mm, 2.0 mm, respectively).
(3.0 mm, 4.0 mm), and their respective area ratios were 12% to 60%. The uneven wear resistance was measured by measuring the uneven wear amount after traveling for a predetermined distance, and showed how much the resistance was improved with respect to a conventional example (without a connecting member) (in%). Table 4 shows the test results.

[0051]

[Table 4]

Thus, the dry operation and uneven wear resistance are better as the area ratio increases, but the operation on ice is 1%.
The peak is approximately 2% to 30%. This is presumably because the increase in the area ratio causes a decrease in the edge component of the sipe 22 and a decrease in drainage performance, resulting in a decrease in on-ice driving performance. Therefore, an area ratio of 10% to 40% is preferable.

[0053]

The pneumatic tire according to the present invention can improve the steering stability, particularly in the early stage of wear, while ensuring the edge effect. Further, by using the method for manufacturing a pneumatic tire according to the present invention, the pneumatic tire can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a perspective view of a block of a pneumatic tire according to a first embodiment of the present invention.

FIG. 2 is a tread plan view of the pneumatic tire according to the first embodiment of the present invention.

FIG. 3 is a plan view of a block according to the first embodiment of the present invention.

FIG. 4 is a plan view of a block according to a second embodiment of the present invention.

FIG. 5 is a plan view of a block according to a third embodiment of the present invention.

FIG. 6 is a plan view of a block according to a comparative example.

FIG. 7 is a plan view of a block according to a comparative example.

FIG. 8 is a plan view of a block according to a comparative example.

FIG. 9 is a plan view of a block according to a comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Pneumatic tire 18 Block (block-shaped land part) 18A-18F Small block 20 Tread surface 22 Sipe 26 Connecting member 26A Connecting part 26B Base

Claims (6)

[Claims] 1. A tread surface comprising: a main groove extending in a tire circumferential direction; and a plurality of block-shaped land portions defined by lug grooves intersecting with the main groove. A pneumatic tire provided with an open sipe, wherein a connection member for connecting small blocks divided by the sipe is provided. 2. The pneumatic tire according to claim 1, wherein the connecting member is a rubber composition. 3. The block member according to claim 1, wherein the connecting member is arranged on a tread side of the block-shaped land portion.
The pneumatic tire as described. 4. The connecting member according to claim 1, wherein a portion arranged in the small block has a larger width in a sipe longitudinal direction than a portion arranged on the sipe. The pneumatic tire as described. 5. The pneumatic tire according to claim 1, wherein the connecting member covers 10% to 40% of a portion that opens to the tread surface of the sipe. 6. An air comprising: a circumferential groove extending in a tire circumferential direction; and a plurality of block-shaped land portions defined by lug grooves intersecting the circumferential groove, and a sipe provided in the block-shaped land portion. A method of manufacturing a tire including a sipe having at least one end opening into the groove in a block-shaped land portion, and vulcanizing and forming a tire having concave portions opposed to each other in both small blocks sandwiching the sipe. And a step of connecting the two small blocks by bonding a connecting member to the recesses of the two small blocks. A method for manufacturing a pneumatic tire, comprising: