JPH01101205A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To improve traveling performance of a heavy duty tire on ice and snow by forming inclined or lateral cipes having enlarged part in the depth on a block. CONSTITUTION:On a block 25 formed on a tread three cipes 27 extending approximately in the lateral direction are provided. Each cipe 29 has a approximately constant cipe width W from the block surface 25a to the vicinity part of the bottom thereof in the depth direction and an enlarged part 27b in circular section on the bottom thereof. With this arrangement, it is possible to improve water absorbing performance and water discharge performance to enhance traveling on ice and snow.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a pneumatic tire, particularly a tread pattern for a heavy-duty pneumatic tire that runs on icy and snowy roads, and also relates to a tread pattern for a pneumatic tire that runs on ice and snow. Advantageously, the present invention relates to a pneumatic tire with improved water absorption performance and drainage performance, and improved performance on ice and snow.

(Conventional technology) Conventionally, in order to ensure performance on snow and ice,
As shown in the figure, a block type snow tire 5 is used which has a large number of blocks 3 divided by a main groove 1 and a narrow groove 2, and a metal or non-metal chain is attached to the snow tire. Snow spike tires, which have spikes driven into the tread, are also used.

However, in recent years, spikes have caused road damage and dust pollution, and there has been a trend to replace snow spike tires with studless tires that do not use spikes. Compared to spiked tires, studless tires are
The drawback is that its performance on ice is not sufficient.

Conventionally, as a pneumatic tire to improve these drawbacks,
There is something like the one shown in Figure 9.10. In FIG. 9, reference numeral 11 denotes a block-type studless pneumatic tire, and the pneumatic tire 11 has a plurality of blocks 16 on the surface of a tread 12 partitioned by a plurality of circumferential grooves 13 and a plurality of lateral grooves 14. As shown in FIG. 10, each block 16 has a tread 12 disposed laterally.
A constant sipe width W2 in the depth direction. A large number of sipes 17 are provided. By arranging these sipes 17, the end portion 17a of the sipe 17 cuts off the water film generated when the pneumatic tire 11 runs on a frozen road surface, improving drainage performance, which improves running performance on frozen roads. is fairly recognized.

(Problem to be solved by the invention) However, when the ground pressure is high, such as in heavy-duty pneumatic tires, a large amount of water gushes out due to ice melting due to this high ground pressure, and a thick water belly is formed. Therefore, there are problems in that the amount of water stored between the sipes is small, resulting in insufficient drainage performance and insufficient driving performance on frozen roads.

Therefore, the present invention increases the volume between the sipes by providing sipes arranged in the block at an angle and/or in a lateral direction with respect to the circumferential direction of the tire, and by making the sipes have an enlarged portion in the depth direction. An object of the present invention is to provide a pneumatic tire which has improved performance on ice and snow by increasing the amount of water stored between sipes and improving water film cutting and drainage performance.

(Means for Solving the Problem) The present inventors have investigated the thickness of the water film and the edge, which is the ability to cut the water film due to the edge of the sipe, in discharging the water film generated on the ice when driving on a frozen road surface. Various studies were conducted on the effectiveness, sipe shape, drainage capacity, water storage capacity, block rigidity, etc. As a result, in order to produce a sufficient edge effect of the sipes, it is recommended to narrow the width of the sipes on the tread surface and provide an enlarged part in the depth direction of the sipes to store water at the bottom or in the middle of the depth. found it to be effective.

The present inventors further conducted various studies and arrived at the present invention.

That is, in the pneumatic tire according to the present invention, in a pneumatic tire having a large number of blocks on the surface of the tread, the blocks are provided with sipes arranged at an angle and/or in a lateral direction, and the sipes are provided at one location in the depth direction. It is characterized by having the enlarged portion as described above.

Here, the width of the sipe is preferably in the range of 0.3 tm to 1.7 tm. The range of 0.3 m to 1.7 m is 0.3 m to 1.7 m.
If it is less than 3 tm, the displacement will be small and sufficient driving performance on frozen roads will not be demonstrated, and if it exceeds 1.7 fi, the rigidity of the block will decrease, the edge effect of the end of the sipe will decrease, and the performance on ice will deteriorate. It is.

Also, the maximum width of the enlarged part of the sipe is 1.2 to 1.2 of the width of the sipe.
5.0 times is preferable. 1.2 to 5.0 times is 1
．． If it is less than 2 times, it is not possible to store enough water in the water film.
Drainage is insufficient. If it exceeds 5.0 times, the rigidity of the block will decrease and the edge effect will not be sufficiently exhibited.

Moreover, on the surface of each block, it is preferable that the total area of the sipes is in the range of 2% to 20% of the surface area of the block. Here, the reason why the ratio is 2% to 20% is because if it is less than 2%, the effect of cutting the water film by the sipes is not sufficient, so 20%
%, uneven wear tends to occur in the block.

Further, it is preferable that the blocks on the surface of the tread be arranged in the center of the tread, and the shoulders of the tread have ribs continuous in the circumferential direction.

(Function) When driving on a frozen road surface, a thick water film is generated due to the high ground pressure. However, since the pneumatic tire of the present invention has a plurality of sipes on the block, sharp water films are formed on the surface of the sipe block. The ends of the sipes cut the water film, and the cut water enters between the sipes 1 and is discharged from between the sipes after the tire leaves the contact area of the road surface.

In addition, since the sipe has an enlarged part in the depth direction, the amount of water that can be stored between the sizes at the ground contact part is compared to the conventional sipe, which has a constant width in the depth direction. and the water absorption performance and drainage performance are increased -0 (Example) Examples of the present invention will be described below based on the drawings.

FIG. 1.2 is a diagram showing a first embodiment of a pneumatic tire according to the present invention.

First, the configuration will be explained. In FIG. 1, 21 is a pneumatic tire, and the pneumatic tire 21 is a truck/bus tire with a tire size of 10.0OR2014PR.The surface 22a of the tread 22 has four tires extending in a zigzag shape in the tire circumferential direction. Circumferential groove 23 and circumferential groove 2
It has a large number of blocks 25 partitioned by horizontal grooves 24 connecting the blocks 25. Each block 25 is provided with three sipes 27 extending substantially laterally. As shown in FIG.
The sipe width W27 is substantially constant up to 7a, and the bottom of the sipe 27 has an enlarged portion 27b having a circular cross section. Here, the sipe width W2. is 0.7 when the internal pressure is filled, the maximum width W of the enlarged portion 27b is 2.0fi, and the sipe 2
The depth Dtq of No. 7 is 17 m. The configuration other than the above is the same as a normal pneumatic tire.

Since the sipe 27 has an enlarged portion 276 at its bottom, even if a thick water film forms between the block 25 and the road surface, the water film is cut by the sharp edge 27c of the sipe 27 on the surface 25a of the block 25. Water is sucked between the sipes 127 and stored in the enlarged portion 27b of the sipes 27. Then, as the tire rotates, it is discharged outward. Therefore, the water on the surface 25a of the block 250 is drained, and the performance on ice is greatly improved. Furthermore, since the block 25 is designed to maintain appropriate rigidity, on-snow performance is maintained sufficiently.

Next, a second embodiment of the present invention will be described.

FIG. 3 is a diagram showing a second embodiment of the pneumatic tire according to the present invention. In the pneumatic tire 31 in the second embodiment, the same components as in the first embodiment are given the same reference numerals.

In the second embodiment, in the first embodiment, a block 25 is provided in the center portion 22b of the tread 22, and a circumferentially continuous rib 33 is provided in the shoulder portion 22c. By providing the rib 33 on the shoulder portion 22c, the wear life of the pneumatic tire is increased.

Next, another example of the sipe provided in the block 25 of the pneumatic tire of the present invention will be described.

The sipe 37 shown in FIG.
This is the case where the sipe 37 has an enlarged part 37a at the bottom and an enlarged part 37b in the middle. When this is applied to a tire size of 10.00 R20, the depth Ds, m of the sipe 37 to the enlarged part 37a is 17 m from the surface 25a of the block 25, and the depth Ds to the enlarged part 37b?
b is 10 squares, the sipe width W is 1.0 squares, and the maximum width WS of enlarged portions 37a and 37b? l, Vl/stb
is preferably 2.5 baskets.

In the sipe 39 shown in FIG. 5, the bottom enlarged portion 39a of the sipe 39 has a semicircular cross section and is asymmetrical with respect to the axis of the sipe 39. This sipe 39 is effective when applied to a tread pattern in which the direction of rotation of a pneumatic tire is constant.

The sipe 41 shown in FIG. 6 has a sipe width W4 in the depth direction of the sipe 41. This is the case when the tail expands.

For example, tire size L S R7,5 for light trucks.
When applied to 0R16, the sipe width W4 of the sipe 41.
is 0.5 fl, and the maximum enlarged part 41a at the bottom of the sipe 41
The sipe width W4□ is 1.2 mm, and the sipe depth I) a
It is preferable that t is 10 m.

Here, the reason why the sipe width W4I of the sipe 41 was expanded to make the hem wider is that when the tire wears out, the amount of water it can absorb decreases, so the sipe width W41 of the sipe 41 is widened to make it easier to absorb water. be.

Further, the size of the present invention may be combined with conventional sipes, or sipes may not be provided in all blocks of the tread. That is, blocks without sipes may be matched.

In addition, although the direction of the sipe was explained in the above-mentioned embodiment as a lateral direction, the present invention is not limited to this embodiment, and may be in a direction inclined to the circumferential direction of the tire. The sipes in the direction may be connected to form a stepped sipe, a zigzag sipe, or a bent sipe.

In addition, Sipe has a negative ratio of the tread, that is, a ratio of the area of the groove to the total area of the tread of 0.5 to 0.
Suitable for tread patterns having 3.

Further, it is preferable that the interval between the sipes is in a range of 5 to 20 times the maximum width of the enlarged portion of the sipes.

Next, test tires (tire size 10.00 R201
4PR) were prepared in three types (Example 1.2, Comparative Example) and the effects of the present invention were confirmed, which will be explained below.

The first example of the test tire is the same as the previous one shown in FIG. 1, and the second example is the same as the previous one shown in FIG. The comparative example is the same as the one shown in FIG. 9 and described above.

Tests were conducted on performance on ice and performance on snow.

The test tire was attached to the rear wheel of the test trunk of a 2-D model car, the tire was filled with the standard internal pressure (JATMA), the standard load (100%) was applied, and the braking distance from a running speed of 20km/H was measured. was measured.

The on-ice performance test was carried out on ice at an outside temperature of -5°C and the on-ice temperature -1°C, and the on-snow performance test was carried out on a compacted snow road surface under the same temperature conditions as described above. The results were converted into an index with the conventional tire (comparative example) set as 100. The smaller the value, the better.

The test results for on-ice performance were 100 for the comparative example, 85 for the first example, and 80 for the second example, indicating that the tire of the present invention showed significantly superior results. In addition, the test results for on-snow performance were 100 for the comparative example, 100 for the first example, and 105 for the second example, showing almost the same performance.

(Effects) As explained above, according to the present invention, the sipes are arranged in the block at an angle and/or in the lateral direction, and the sipes have an enlarged portion in the depth direction. By increasing the volume, the amount of water stored between the rhinoceroses 1 can be increased, the water film cutting and drainage performance can be improved, and the performance on ice and snow can be significantly improved.

[Brief explanation of the drawing]

Fig. 1.2 is a diagram showing a first embodiment of the pneumatic tire according to the present invention, Fig. 1 is a partial plan view thereof, and Fig. 2 is an enlarged cross-sectional view taken along the line ■-■ in Fig. 1. It is. FIG. 3 is a partial plan view showing a second embodiment of the present invention. 4 to 6 are partial cross-sectional views showing other embodiments of the sipe of the pneumatic tire according to the present invention. Figures 7 to 10 are diagrams showing conventional tires, with Figure 7 being a partial plan view, Figure 8 being a cross-sectional view taken along the ■-■ arrow in Figure 7, and Figure 9 being a view of another tire. FIG. 10 is a sectional view taken along the line X--X in FIG. 9. 21.31...Pneumatic tire, 22...
... Tread, 23 ... Circumferential groove, 24 ... Lateral groove, 25 ... Block, 27.37.39.41 ... Sipe, 27a,
37b, 39a, 41a = enlarged portion.

Claims (1)

[Claims] A pneumatic tire having a large number of blocks on the surface of the tread, characterized in that the blocks are provided with sipes arranged at an angle and/or in a lateral direction, and the sipes have one or more enlarged portions in the depth direction. pneumatic tires.