JP3110783B2 - 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 having a narrow cut in a tread land portion for the purpose of improving braking performance on icy and snowy roads.

[0002]

2. Description of the Related Art Conventionally, a pneumatic radial tire provided with a lug pattern comprising a large number of tread land portions defined on a tire tread surface of a tread portion by a main groove in a tire circumferential direction and a lug groove in a direction crossing the main groove. In order to improve braking and traction performance (edge effect) on ice and snowy roads, a plurality of narrow cuts (hereinafter referred to as sipes) are provided on each tread land portion. For example, in the pneumatic tire disclosed in JP-A-2-179509, as shown in FIG.
More than two sipes 6 in the direction that intersects the tire rotation direction
2, 64, ..., 66 are provided, and among these sipes,
The depth of the sipe 62 located closest to the end portion 60A of the tread land portion 60 on the stepping side is the smallest, and the depth of the sipe located on the kick-up side 60B of the tread land portion 60 is gradually increased. As a result, the rigidity in each tread land portion 60 is larger on the stepping side 60A than on the kick-up side 60B, and the lifting of the tread land portion 60 from the road surface on the stepping side 60A during braking is suppressed. Also, the difference in the amount of wear between the tread side portion 60A and the kick-up side 60B of the tread land portion 60 is reduced, and uneven wear can be suppressed, and the tread surface of the tread land portion 60 does not decrease. improves.

Further, in the pneumatic tire disclosed in Japanese Patent Application Laid-Open No. 2-169307, as shown in FIG. 9, the stepping end 70A of the sipe 72 closest to the stepping end 70A of the tread land portion 70. Distance L1 from
Is greater than one-third and less than or equal to one-half the length L2 of the tread land portion 70 in the tire circumferential direction. by this,
The rigidity in each tread land portion 70 is significantly greater on the tread side 70A than on the kick-up side 70B, and during braking, the tread side 70A does not rise and uneven wear can be suppressed, and the tread surface of the tread land portion 70 decreases. Since it does not, the braking performance of the tire is improved. A related prior art is disclosed in Japanese Patent Application Laid-Open No. Hei 2-182502.

[0004] However, in these pneumatic tires, when the wear of the tread land portion progresses, the depth of the sipe relatively decreases, and it becomes difficult to maintain the above-mentioned performance provided by the depth of the sipe. The problem described above occurs.

[0005]

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide a pneumatic radial tire having a sufficient edge effect and a suitable rigidity even when the tread land is worn.

[0006]

In order to achieve the above object, according to the present invention, a main groove formed on a tire tread surface of a tread portion along a tire circumferential direction, and a main groove formed along a tire width direction. A pneumatic radial tire including a formed lug groove, and a tread land portion defined by the main groove and the lug groove, wherein a plurality of pneumatic radial tires are formed on the tread land portion substantially in parallel with the lug groove. , zig-zag also in the depth direction
The cut thin is wavy, possess, the tread land portion
The notch located closest to the stepping end
The pitch of the zag is the longest, and the tread land sequentially
The zigzag of the notch located on the kick-up side of the part
It is characterized by a shorter pitch .

[0007] To achieve the above object, the present invention according to claim 2 provides a pneumatic radial tire according to claim 1.
In the above, the notches are pitched in the depth direction.
And the amplitude gradually decreases .

[0008]

In the pneumatic radial tire according to the first aspect of the present invention, when the pitch of each cut is reduced, the peaks and valleys are reduced.
And the tread land is easily deformed.
As you increase the pitch of each cut, peaks and valleys
And the tread land is less likely to deform
Become. For this reason, the pitch of each cut is
Notch pitch closest to the stepping end
Is the longest, and is located sequentially on the kicking side of the tread land
The cut pitch is shorter. This allows each
The rigidity inside the tread land is greater on the stepping side than on the kicking side
The road surface on the tread side of each tread land during braking
The lift from the ground is suppressed, and each tread land part is stepped on.
The difference in the amount of wear between the only side and the
Not reduce the tread surface of each tread land.
Therefore, the braking performance of the tire can be improved. Also,
Tread according to the depth or position of the cut as before
Compared to adjusting the flexural rigidity of the land,
Hardly affected by abrasion, sufficient for wear on tread land
Edge effect and appropriate rigidity can be maintained.

According to a second aspect of the present invention, there is provided a pneumatic radial tire according to the first aspect.
In the tire, the cut is made in the depth direction.
Tread and amplitude gradually decrease,
Have sufficient edge effect and appropriate rigidity even when worn
Can be.

[0010]

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

As shown in FIG. 2, on the tire tread surface of the tread portion 12 of the pneumatic radial tire 10 of the present embodiment, main grooves 14, 16, 18, 20 along the tire circumferential direction are provided.
Are formed at substantially equal intervals. On the tire tread of the tread portion 12 of the pneumatic radial tire 10, lug grooves 2 crossing the main grooves 14, 16, 18, and 20 are provided.
2 are formed at predetermined intervals in the tire circumferential direction. Therefore, the main grooves 14, 1
A plurality of tread land portions 24 defined by 6, 18, 20 and the lug grooves 22 are formed. Further, in each tread land portion 24 of the tread portion 12, sipes 26, 28, 30 are formed at predetermined intervals in the tire circumferential direction at substantially the same depth in substantially parallel to the lug grooves 22.

As shown in FIG. 1, each sipe 26, 28, 30 of the tread land portion 24 is zigzag in the depth direction, and the tread land formed across each sipe 26, 28, 30 is formed. The peak 32 and the valley 34 of the part 24 are engaged. Further, among the sipes 26, 28 and 30, the zigzag pitch P1 of the sipe 26 located closest to the tread side 24A end of the tread land portion 24 is the longest, and the tread land portion 24 is sequentially kicked up. The pitches P2 and P3 of the zigzag are shorter as sipes 28 and 30 are located at 24B.

Next, the operation of this embodiment will be described.

In the pneumatic radial tire 10 of the present embodiment, sipes 26, 28, 30 are formed in the tread land portion 24 in a zigzag manner in the depth direction substantially in parallel with the lug grooves 22. Therefore, the edge effect of the tread land portion 24 can be ensured by each of the sipes 26, 28, and 30 in the same manner as the conventional sipe linearly formed in the depth direction, and the zigzag mountain of the tread land portion 24 can be secured. The engagement between the valleys 32 and the valleys 34 can maintain the bending rigidity of the tread land portion 24 and suppress uneven wear.

That is, if the pitches P1, P2, P3 of the sipes 26, 28, 30 are reduced, respectively, the gap between the peak 32 and the valley 34 is likely to occur, and the tread land portion 24 is easily deformed. , 28, 30 pitch P
When 1, P2, and P3 are increased, the gap between the peak 32 and the valley 34 is less likely to occur, and the tread land portion 24 is less likely to deform. Therefore, the pitch P of each sipe 26, 28, 30
1, P2 and P3 are the tread side 24 of the tread land portion 24.
The pitch P1 of the sipe 26 located closest to the end A is the longest, and the pitches P2 and P3 of the sipes 28 and 30 located sequentially on the kick-up side 24B of the tread land portion 24 are gradually reduced. As a result, the rigidity in each tread land portion 24 is greater on the stepping side 24A than on the kicking side 24B,
At the time of braking, the lifting of the tread land portion 24 from the tread side 24A of the tread land portion 24 from the road surface is suppressed, and the difference in the amount of wear between the tread side 24A and the kick-up side 24B of each tread land portion 24 is reduced, and uneven wear can be prevented. Each tread land part 2
Since the ground contact surface of No. 4 does not decrease, the braking performance of the tire can be improved. In addition, compared with the conventional case where the bending rigidity of the tread land portion is adjusted by the depth or position of the sipe, the tread land portion 24 is hardly affected by abrasion and the tread land portion 24 has sufficient edge effect even when worn. And appropriate rigidity can be maintained.

Next, a comparative example of the present invention will be described with reference to FIG.

The same members as in the first embodiment are
The same reference numerals are given and the description is omitted.

As shown in FIG. 3, each sipe 36, 38, 40 of the tread land portion 24 is zigzag in the depth direction, and the tread land formed across each sipe 36, 38, 40 is formed. The peak 32 and the valley 34 of the part 24 are engaged. Further, of the sipes 36, 38, and 40, the depth D1 of the sipe 36 located closest to the stepping side 24A end of the tread land portion 24 is the shallowest, and the kicking side 24B of the tread land portion 24 is sequentially formed. Sipe 38, located at
The depths D2 and D3 are deepened by about 40.

Next, the operation of the comparative example will be described.

In the pneumatic radial tire 10 of the comparative example, sipes 36, 38, and 40 zigzag in the depth direction are formed in the tread land portion 24 substantially in parallel with the lug grooves 22. Accordingly, each of the sipes 36, 38, and 40 is similar to the conventional sipe linearly formed in the depth direction.
The edge effect of the tread land portion 24 can be secured, and the zigzag peaks 32 and valleys 34 of the tread land portion 24 can be obtained.
The bending rigidity of the tread land portion 24 is maintained, and uneven wear can be suppressed. For this reason, compared to the conventional narrow notch that is linear in the depth direction,
It is hardly affected by the wear of the tread land portion, and can maintain a sufficient edge effect and appropriate rigidity even when the tread land portion is worn.

In the first embodiment and the comparative example, all the sipes of the tread land portion 24 are zigzag. Instead, as shown in FIGS. The sipe 42 may be formed in a zigzag manner in the depth direction at a portion where the rigidity of the tread land portion 24 is desired to be improved, by combining the sipe 42 having a zigzag shape and the sipe 44 being linear in the depth direction. In addition, as shown in FIG. 7A, sipe 46, 48, 50 which is zigzag in the depth direction and is wavy in the depth direction may be provided instead of the sipe.
As shown in (B), sipes 52, 54, 56 in which the pitch and amplitude gradually decrease in the depth direction may be provided.

(Experimental example 1) Pneumatic radial tire (tire size 195 / 70R14) of the first embodiment of the present invention
And a conventional pneumatic radial tire with the specifications shown in Table 1, respectively.
The braking is applied from km / h, and the braking distance at that time is measured. The result is calculated by setting the braking distance of the conventional pneumatic radial tire to 1
The index is shown in Table 1 as 00.

(Experimental example 2) The pneumatic radial tire (tire size 195 / 70R14) of this embodiment and a conventional pneumatic radial tire were prototyped according to the specifications shown in Table 1, respectively.
Each tire was mounted on an actual vehicle, and after traveling 1000 km on a course with a high frequency of braking and driving and a slalom course, the level difference between the stepping side of the tread land and the kick-up side was measured. The abrasion resistance of the pneumatic radial tire was set to 100 and indexed in Table 1.

[0024]

[Table 1]

From the above results, it was clarified that the pneumatic radial tire of this embodiment is superior to the conventional pneumatic radial tire.

[0026]

As described above, the present invention has an excellent effect that a sufficient edge effect and appropriate rigidity can be obtained even when the tread land portion is worn.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a tread land portion of a pneumatic radial tire according to a first embodiment of the present invention.

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

FIG. 3 is a plan view showing a tread of a pneumatic radial tire according to a comparative example of the present invention.

FIG. 4 is a perspective view showing a tread land portion of a pneumatic radial tire according to another comparative example of the present invention.

FIG. 5 is a perspective view showing a tread land portion of a pneumatic radial tire according to another comparative example of the present invention.

FIG. 6 is a perspective view showing a tread land portion of a pneumatic radial tire according to another comparative example of the present invention.

FIGS. 7A and 7B are perspective views showing a tread land portion of a pneumatic radial tire according to another embodiment of the present invention.

FIG. 8 is a side sectional view showing a tread land portion of a conventional pneumatic radial tire.

FIG. 9 is a side sectional view showing a tread land portion of another conventional pneumatic radial tire.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Pneumatic radial tire 12 Tread part 14 Main groove 16 Main groove 18 Main groove 20 Main groove 22 Lug groove 24 Tread land part 26 Sipe 28 Sipe 30 Sipe 32 Mountain 34 Valley 36 Sipe 38 Sipe 40 Sipe 42 Sipe 44 Sipe 46 Sipe 48 Sipe 50 Sipe 52 Sipe 54 Sipe 56 Sipe

Claims (2)

(57) [Claims] 1. A main groove formed along a tire circumferential direction on a tire tread surface of a tread portion, a lug groove formed along a tire width direction, and a tread land defined by the main groove and the lug groove. a pneumatic radial tire having a part, the said lug grooves substantially parallel to a plurality of forming the cuts thin is a zigzag or undulating in the depth direction, possess the tread land portion, a tread land Closest to the stepping end of the part
The zigzag pitch of the notch located at the longest
It is located on the kicking side of the tread land part in sequence
The pneumatic radial tire, wherein the pitch of the zigzag is shorter as the cuts are made . 2. The notch is formed in a depth direction.
Contractors characterized by gradually decreasing pitch and amplitude
The pneumatic radial tire according to claim 1.