JPH04310407A - Studless tire - Google Patents

Abstract

PURPOSE:To suppress fall-out of each sub-block and enable shortening of braking distance in braking on iced ground surface by providing cuts in block surface zigzag or in waveform perpendicularly to the surface of the block. CONSTITUTION:Four main grooves 10, 11, 12, and 13 are provided on the tread surface T in circumferential direction EE of a tire and along the periphery of the tire, and multiple auxiliary grooves 20 for connecting to the main grooves are also provided on it from one shoulder 14 to the other shoulder 14 in lateral direction of the tire to form multiple blocks 30. In each of the blocks 30, two cuts 40 are provided from one end of the block 30 to the other end in lateral direction to divide it into multiple sub-blocks 31, 32, and 33. The cuts 40 are formed zigzag in the blocks 30 perpendicularly to the surface of the blocks and, during the travel, the respective sub-blocks 31, 32, and 33 support for each other to suppress fall-out in the direction opposite to that of the traveling, thus maintaining sufficient ground contact area.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to the improvement of a studless tire suitable for driving on ice, and more particularly to a studless tire with improved braking performance on icy roads and uneven wear resistance on normal roads. be.

0002

2. Description of the Related Art The mainstream studless tires are those that have improved running performance on ice due to the edge effect of cuts carved into the surface of blocks formed on the tread surface. An example of a block of this studless tire is shown in FIG. FIG. 8 shows a tread surface divided by a plurality of main grooves (not shown) formed in the tire circumferential direction and a plurality of sub-grooves 2 formed in a direction intersecting the main grooves (tire width direction). 3 shows a cross section of the block 3 in the tire circumferential direction. In FIG. 8, two notches 4 are carved on the surface of the block 3 to improve movement performance on ice, and this allows the block 3 to be divided into three sub-blocks 3.
' is divided into '.

However, in a studless tire having such a block 3, since the notch 4 is formed linearly in the normal direction of the surface of the block 3, as shown in FIG.
As shown in the figure, when braking when driving on an icy road surface 5,
Each sub-block 3' falls in the direction opposite to the traveling direction M, and as a result, as shown in FIG. The area of 6 will decrease.

[0004] Therefore, in conventional studless tires, when braking when driving on an icy road surface, the ground contact area decreases, resulting in poor contact with the ice surface and weakening the friction effect with the ice surface. Particularly when the tire is applied to a vehicle with relatively high ground contact pressure, such as a small truck, there is a problem in that the braking distance becomes long. In addition, with such conventional studless tires, even when driving on a dry normal road surface such as a summer road surface, due to the collapse of each sub-block 3' during braking as described above,
There was a problem in that each sub-block 3' was prone to uneven wear such as step wear (heel-and-dough wear).

[0005]

OBJECTS OF THE INVENTION The present invention has been made to solve the above-mentioned problems with the conventional studless tires, and has improved braking performance on icy roads and uneven wear resistance on normal roads. The purpose of this invention is to provide a studless tire with improved characteristics.

[0006]

[Means for Solving the Problems] The studless tire of the present invention has a plurality of main grooves provided on the tread surface in the tire circumferential direction over one circumference of the tire, and a plurality of sub grooves connecting these main grooves in the tire width direction. A plurality of blocks are formed by forming a plurality of blocks, each of which has at least one notch cut in the width direction of the tire, and the notch is formed in a zigzag or wave shape in the normal direction of the surface of the block. It is characterized by

[0007] In this way, in the present invention, since the notches carved on the surface of the block are formed in a zigzag shape or a wave shape in the normal direction of the surface of the block, the collapse of each sub-block during running is suppressed. , it is possible to shorten the braking distance when braking on icy roads compared to conventional models, and it is also effective in preventing uneven wear such as heel-and-dough wear when braking on dry normal roads such as summer roads. can be suppressed.

The structure of the present invention will be explained in detail below with reference to the drawings. FIG. 1 is an explanatory plan view showing an example of the tread pattern of the studless tire of the present invention. Figure 1
In the tread surface T, four main grooves 10, 11, 12, and 13 are provided over one circumference of the tire in the tire circumferential direction EE', and a plurality of sub grooves 20 connecting these main grooves are provided on one side. It is provided in the width direction of the tire from one shoulder portion 14 to the other shoulder portion 14, thereby forming a large number of blocks 30. t is the equator line.

[0009] All of the blocks 30 have two notches 40 carved on their surfaces in the tire width direction from one end of the block 30 to the other, so that each block 30 has a plurality of sub-blocks 31, It is divided into 32 and 33 parts. At least one notch 40 may be formed on the surface of the block 30. In addition, although the notch 40 is provided in a direction perpendicular to the tire circumferential direction EE' in FIG. 1, it is also possible to arrange the notch 40 at an angle of 45° to 90° with respect to the tire circumferential direction EE'. be.

As shown in FIGS. 2 to 5, which show an example of the cross section taken along the line A-A in FIG. Or it is formed in a wave shape (FIGS. 4 and 5). Here, the height of the block 30 is a, the depth of the cut 40 is b, and the cut 4
When the zigzag bending angle or waveform bending angle of 0 is θ, b=a×(0.3 to 1.0), 60°≦θ
It is preferable that the angle is ≦120°. If b is less than 0.3a, the edge effect of the cut will be small, while if it exceeds 1.0a, it will be difficult to take out the tire from the mold after tire molding and vulcanization. In addition, if θ is less than 60°, it will be difficult to take out the tire from the mold after tire molding and vulcanization.
If it exceeds 20 degrees, it will not be possible to secure a sufficient ground contact area during braking, and it will not be possible to sufficiently suppress the collapse of each sub-block.

In FIG. 2, the cut 40 is at θ=90°, b
= 0.85a, and amplitude = 5.0 mm. In FIG. 3, one cut 40a is θ=100°, b=1.0a
, and has a zigzag shape with an amplitude of 5.0 mm, and the other notch 40b has an angle of θ=90°, b=1.0a, and has a tapered shape whose amplitude gradually decreases toward the center of the tire. It is preferable that the block surface side amplitude c and the block bottom side amplitude d of the notch 40b have a relationship of d/c≦1.0 (c=5.0 mm, d=3.0 m
m). In this way, each block 30 can be provided with different types of cuts 40a and 40b. Figure 4
In this case, the cut 40 is formed in a wave shape in the normal direction of the block 30, θ=70°, b=1.0a, amplitude=5.
It is 0 mm. Also in FIG. 5, the cut 40 is formed in a wave shape in the normal direction of the block 30, and θ=90°,
b=0.75a, amplitude=4.0 mm.

By forming the notches 40 in a zigzag or wave shape in the normal direction of the block 30 in this way, the sub-blocks 31, 32 and 33 support each other during running, as shown in FIG. As a result, a sufficient ground contact area 60 can be secured as shown in FIG. 7, thereby shortening the braking distance, especially when braking on an icy road surface 50. becomes possible. Further, step wear on normal road surfaces can be reduced.

[0013]

[Example] For the tread surface of a tire size: 6.50R16 10PR, five types of radial tires according to the present invention having the blocks shown in FIGS. 1 to 5 described above and a conventional tire having the blocks shown in FIG. 8 were prepared. produced radial tires. All other structures such as the carcass layer and belt layer and manufacturing conditions were the same for all tires.

That is, in FIG. 1, the ground contact width W of the tread is 140 mm, the groove width of the main grooves 10, 11, 12, and 13 is 5.0 mm, the groove depth is 14.0 mm, and the groove width of the minor groove 20 is 140 mm. : 9.0 mm, groove depth: 12.0 mm
By forming blocks 30 with a length of 36.0 mm in the circumferential direction, and providing cuts in the shapes shown in Table 1 in the circumferential direction of each block 30 at intervals of 12.0 mm and parallel to the width direction of the tire, six types of cuts were made. got a tire.

[0015] Regarding these six types of tires, the rim used was 16 x 5.50 F SDC, and the air pressure was 5.5 kg.
/cm2, the results of evaluating the braking performance on ice and uneven wear resistance are also shown in Table 1. In addition, in Table 1, all index evaluations are shown when the conventional tire is set as 100, and in all cases, the larger the index, the better the results. Ice braking performance test vehicle: 3000cc, small truck Road surface:
Icy road surface evaluation method: Apply sudden braking at an initial speed of 40km/h and measure the braking distance from when the tires lock until the car stops. Uneven wear resistance test vehicle: 3000cc, small truck road surface:
Dry pavement evaluation method: 10,000 at an average speed of 40 km/h
km Visually evaluate the occurrence of step wear between sub-blocks on the tread surface after running.

[0016]

As is clear from the results in Table 1, the tires of the present invention have the same braking performance on snow and wear resistance as the conventional tires, but the braking performance on ice and resistance to uneven wear are significantly improved. .

[0018]

[Effects of the Invention] As explained above in detail, according to the studless tire of the present invention, not only can the braking distance when braking on an icy road surface be shortened compared to the conventional one, but also the braking performance is excellent in summer. When braking on a normal road surface such as a dry road surface, uneven wear such as heel-and-dough wear can be effectively suppressed.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an example of a tread pattern of a studless tire of the present invention.

FIG. 2 is a cross-sectional view showing an example of the cut shape of the block of the studless tire of the present invention.

FIG. 3 is a sectional view showing an example of the cut shape of the block of the studless tire of the present invention.

FIG. 4 is a sectional view showing an example of the cut shape of the block of the studless tire of the present invention.

FIG. 5 is a sectional view showing an example of the cut shape of the block of the studless tire of the present invention.

FIG. 6 is a sectional view showing the ground contact state of the block of the studless tire of the present invention during braking on an icy road surface.

FIG. 7 is an explanatory plan view showing the ground contact state of the block of the studless tire of the present invention during braking on an icy road surface.

FIG. 8 is a cross-sectional view showing an example of the cut shape of a block of a conventional studless tire.

FIG. 9 is a sectional view showing the ground contact state of a block of a conventional studless tire during braking on an icy road surface.

FIG. 10 is an explanatory plan view showing the ground contact state of a block of a conventional studless tire when braking on an icy road surface.

[Explanation of symbols]

T Tread surface
10, 11, 12, 13 Main groove

Claims (1)

[Claims] Claim 1: A plurality of main grooves are provided on the tread surface in the tire circumferential direction over one circumference of the tire, and a plurality of sub grooves connecting these main grooves are provided in the tire width direction to form a plurality of blocks. A studless tire in which at least one notch is carved in the tire width direction on the surface of each block, and the notch is formed in a zigzag shape or a wave shape in the normal direction of the surface of the block.