JPH02225110A - Pneumatic tire for vehicle - Google Patents

Abstract

PURPOSE:To improve ice and snow performance without inviting biased abrasion by extending a large number of sipes cut into respective blocks in a longitudinal block group in zigzag like along peripheral edges of a tread, while making at least respective one-side ends thereof open to lateral grooves. CONSTITUTION:A central peripheral groove 1, a pair of peripheral grooves 1a for holding the above between them, and numerous lateral grooves 2a-2c for connecting these respective peripheral grooves 1, 1a and tread ends to each other are respectively arranged on a tread T, therewith the tread T is divided in a longitudinal block group B consisting of numerous blocks 3a-3c. A large number of sipes 5a, 5b cut in from respective lateral grooves 2a-2c are arranged in respective blocks 3a-3c. In this case, respective sipes 5a, 5b are made to extend along the peripheral edges of the tread T in zigzag like, while the sipes are made to open at least respective one-side ends of respective ones to respective lateral grooves 2a-2c. Thereby, traction performance and turning performance on snow and ice are improved without inviting biased abrasion of a tire.

Description

[Detailed Description of the Invention] (Field of Industrial Application) This invention relates to improving the tread pattern of pneumatic tires for vehicles, especially studless tires suitable for use on icy and snowy roads, and particularly to improve performance on ice. That is.

Spiked tires have been used on ice and snowy roads, but since spike bins cause severe damage to snow-removed roads and road surfaces, it is now recommended to use so-called studless tires, which can be used without spike pins even on ice and snow. .

The tread pattern of this type of tire is often block type or rib plotter type, and is narrow enough that each block is virtually closed to each other under the contact patch during load transfer of the tire, exclusively to increase traction on snow. It is customary to have multiple width cuts, and these cuts are usually called sipes.

(Prior art) Tread patterns in which sipes are arranged are well known, and there is no need to present any literature on them, but they are usually horizontal sipes that are cut from the circumferential groove and extend linearly across the tread circumferential line. be.

(Problems to be Solved by the Invention) In order to improve the performance of studless tires, first of all, it is necessary to catch snow on snow, that is, to make the snow be caught by the edges and lateral grooves of the blocks of the tire tread.
On powered water, it is important to use multiple sipes to increase the block edge and catch ice, so there is a tendency to use sipes frequently.

However, due to the soft rubber of studless tires, the heavy use of sideways sipes results in extremely poor wear after driving.In other words, although the force from being caught by an edge is stronger, the sipe surface directly receives the reaction force from the road surface. Therefore, blocks containing sipes wear out like a saw blade. Furthermore, since the lateral grooves and sipes are arranged to cross the tread circumference, there is a problem that the turning performance is poor, especially on ice.

Therefore, an object of the present invention is to propose a tread pattern that has excellent turning performance especially on ice and can suppress uneven wear.

(Means for solving the problem) The inventors believe that in order to improve performance on snow, it is advantageous to arrange a large number of lateral grooves to increase the chances of catching snow.
On the other hand, we found that increasing the number of lateral grooves makes the block smaller, making it easier for the uneven wear caused by the sipes mentioned above to progress, and after considering various ways to improve this uneven wear, we found that by extending the sipes along the tread circumference. Moreover, it was found that it is effective to make the shape zigzag.

That is, the present invention has a plurality of vertical block groups partitioned by a plurality of circumferential grooves extending along the tread circumferential line and a large number of lateral grooves connecting these circumferential grooves, and each block of the vertical block group has a The pneumatic tire is equipped with a large number of sipes cut from grooves, and the sipes extend in a zigzag shape along the tread circumference, with at least one end opening into a lateral groove. Uses pneumatic tires.

Now, FIG. 1 shows a tread pattern according to the present invention,
In the figure, the entire surface of the tread is covered with T, and this tread T is connected to the center circumferential groove 1, the pair of circumferential grooves 1a sandwiching it, and the 1.18 grooves and the circumferential groove 1a to the tread ends. It was divided by horizontal grooves 2a, 2b, and 2c to form a vertical block group B of four columns, two in the center and one on each side. Note that S in the figure represents a shoulder.

Further, in the figure, 3a, 3b, and 3C indicate blocks, and among the blocks 3b and 3C that sandwich the horizontal groove 20 having a relatively narrow width, the block 3b is a curved portion 4 extending at the same angle as the circumferential groove.
Provided with.

Each block 3a, 3b and 3C has a horizontal groove 2a.

Sipes 5a and 5b are cut from 2b or 2C and extend in a zigzag shape along the tread circumference, and are arranged in parallel in a direction orthogonal to the tread circumference. Note that the sipe 5a crosses the block and has horizontal grooves at both ends.
On the other hand, the groove 5b has only one end opened into a horizontal groove.

Each sipe has a pitch P of 2 to 10 aa and an amplitude W of 6
The sipes have a zigzag shape in the range of ~20 circles, and the sipes are arranged in parallel in a direction across the tread circumference and at least in the same phase within the same block. The spacing between the sipes in the same block is 15 to 45%, preferably 25 to 45%, of the maximum width of the block in the direction orthogonal to the tread circumference.
If it is 35%, block rigidity will not be sacrificed.

Furthermore, as shown in FIG. 2, the depth of the sipes is preferably shallower at the ends, at least one end, than at the middle. That is, in the figure, the depth d at the end of length e is 20 to 50%, preferably 30 to 40%, of the depth D at the middle part.
That is. Note that the length e of the end portion is in the range of 1 to 10 m, preferably 2 to 5 m+s.

Further, when three or more sipes are provided in one block, the depth of the sipes located on both sides is set to 80% or less, preferably 60% or less of the depth of the other sipes.

(Function) By extending the sipes arranged in the tire tread blocks along the tread circumference, the rigidity in the circumferential direction, which receives the most load during tire transfer, can be significantly improved compared to the conventional horizontal size. This makes it possible to avoid uneven wear.

However, on the other hand, if the sipes extend along the tread circumference, the traction force during straight running may be reduced, but this problem can be solved by making the sipes zigzag in shape.

In other words, a zigzag shape does not simply extend in one direction like a straight line shape, but is a composite of a straight line and its intersecting lines.Therefore, a zigzag shaped sipe that extends along the tread circumference acts as a sideways sipe. This also ensures traction when going straight.

(Example) According to the tread pattern shown in FIG. 1, a trial tire for LT with a tire size of 7.00-16 was manufactured. The full circumferential width of this prototype tire is 10 to 12 mm in the direction perpendicular to the tire circumferential line.
The pitch of the zigzag in the sipe cut into the block is 5mm, the same amplitude is 2mm, and the cutting width of the sipe is 0.
7mi, the same depth is 3mm at the end (length, 3fflfll).
5 tm, 10.5 am in the middle part, and the sipe interval within each block was 8 songs.

Similarly, a tire of the same size was prototyped with the conventional tread pattern shown in FIG. The width and depth of the sipes in this tire are 0.7 mm and 10.5 mm, respectively.
It was set as m.

The test tires were evaluated in a snow performance test, an ice performance test, and an uneven wear test, and the results are shown in the table below.

For comparison, similar evaluations were also conducted on tires of the same type having the tread pattern shown in FIG. 3, and the results are also shown in the table below.

The test was conducted at a tire pressure of 4.5 kg/c for the front wheels and 3.5 kg/c for the rear wheels.
The evaluation was made using an index with each test result of the comparative tire taken as 100.

The on-snow performance test evaluates the driver's feeling during various runs (starting, braking, climbing and cornering) on a test course with a smooth, compacted snow surface, and the on-ice performance test evaluates the driver's feeling during various runs (starting, braking, climbing and cornering) on a test course on a waterway surface. The evaluation of the driver's feeling during braking, climbing and cornering, and the uneven wear test were conducted by actually measuring the difference in level due to wear between the tires during normal driving on a ship route.

(Effect of the invention) According to the invention, traction performance and turning performance on snow and ice can be improved without causing uneven wear,
An optimal tread pattern for studless tires can be provided.

[Brief explanation of the drawing]

FIG. 1 is a developed view of a tread pattern according to the present invention, FIG. 2 is a sectional view of a sipe, and FIG. 3 is a developed view showing a tread pattern of a conventional studless tire. 1.1a・” Circumferential groove 2a, 2b, 2cm・・Horizontal groove 3
a, 3 b, 3 c---Block 4...
Bay-shaped portion 5a, 5b... Sipe B... Column block group T... Tread S... Shoulder Fig. 3

Claims (1)

[Claims] 1. It has a plurality of vertical block groups partitioned by a plurality of circumferential grooves extending along the tread circumferential line and a large number of lateral grooves connecting these circumferential grooves, and each of the vertical block groups has a A pneumatic tire having a block with a large number of sipes cut from grooves, the sipes extending in a zigzag shape along the tread circumference, and at least one end opening into a lateral groove. Pneumatic tires for vehicles. 2. The tire according to claim 1, wherein the amplitude and pitch of the zigzag-shaped sipes are in the range of 2 to 10 mm and 6 to 20 mm, respectively. 3. The tire according to claim 1, wherein the sipes are arranged in parallel in a direction transverse to the tread circumference and at least in the same phase within the same block. 4. The spacing between sipes in the same block is 15 to 45 mm, which is the maximum width of the block in the direction orthogonal to the tread circumference.
%. 5. The tire according to claim 1, wherein the depth of the sipe is shallower at least at one end than at the middle portion.