JPH0424105A - All weather pneumatic tire - Google Patents

Abstract

PURPOSE:To make improvements in partial wear resistance and tractive performance on ice, snow or the like without entailing any sacrifice of steering stability on a general road by installing each platform in many transverse grooves connecting an interval between peripheral grooves and these grooves and each tread end, and specifying the clearance and height. CONSTITUTION:A tread is provided with a four-rowed file block group B separated by each peripheral groove 1 formed zigzag and extending along the circumference of a tread center in substance and other peripheral grooves 1a holding the former in between and transverse grooves 2a-2c connecting an interval between the peripheral grooves 1 and the other peripheral grooves 1a and each tread end E. In this case, in these transverse grooves 2a and 2b partitioning the file block group B at central two rows, there is provided each platform 5 consisting of bulging a part of the groove bottom. This platform 5 is lower than height H from each transverse groove bottom of blocks 3a and 3b at both sides, and it is at height (h) where a top part of the platform 5 is grounded under the ground plane during tire load rolling and, what is more, it is protruded over the whole width of each transverse groove that left such a clearance (w) as a degree virtually closed together with each side wall of the blocks 3a and 3b at both sides.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to improving the tread pattern of pneumatic tires, especially all-weather pneumatic tires, without sacrificing handling stability on general roads. ,
The purpose is to improve uneven wear resistance and traction on road surfaces such as snow.

(Prior art) The tread pattern of this type of tire is often a block type or a replug type.The block type is mainly advantageous for increasing traction on ice and snow, but it also improves handling stability and durability on ordinary roads. It is disadvantageous in terms of uneven wear resistance and noise reduction, whereas the replug type has increased block rigidity and can reduce the tread porosity, so it is advantageous in terms of handling stability, uneven wear resistance, and noise reduction on general roads. , performance on ice and snow is poor because the movement of the block in response to circumferential input to the tire is restricted.

(Problems to be Solved by the Invention) In other words, both types of conventional tread patterns have a problem in that they do not satisfy all of the wide range of characteristics required of all-weather tires.

Therefore, it is an object of the present invention to improve uneven wear resistance and traction performance on ice and snow without sacrificing steering stability on ordinary roads.

(Means for Solving the Problems) The present invention has a plurality of circumferential grooves that have a zigzag shape and extend substantially along the tread circumferential line, and a large number of transverse grooves that connect between these circumferential grooves and between the circumferential grooves and the tread edge. The pneumatic tire has a plurality of vertical block groups divided into sections, and the transverse groove has a platform whose groove bottom is raised to a lower level than the block surfaces on both sides, and the cough platform is designed to prevent the tire from rolling under load. This all-weather pneumatic tire is characterized by having a gap that virtually closes with the block walls on both sides below the ground contact surface of the tire, and a height such that the top portion touches the ground.

Now, FIG. 1 shows a tread pattern according to the present invention.

The illustrated tread includes a circumferential groove 1 that has a zigzag shape and extends substantially along the circumference of the tread center, a circumferential groove 1a sandwiching the circumferential groove 1, and a circumferential groove that connects the circumferential grooves and between the circumferential groove 1a and the tread end E. Transverse grooves 2a to 2C with a slightly shallower depth than
It has a column block group B of four columns, two columns in the center and one column on each side, divided by and.

The vertical block group B in two central rows has blocks 3a and 3b having different surface areas arranged alternately, while the vertical block group B in one row on each side has blocks 3c of the same shape arranged at equal intervals. Blocks 3a and 3b have narrow grooves (or notches) 4a that are open on both sides or on one side and extend in a zigzag shape along the transverse groove 2a or 2b, and block 3c has narrow grooves (or notches) that are open on one side and extend in a zigzag shape along the circumference of the tread. Each of them is provided with a narrow groove (or notch) 4b.

Also, a transverse groove 2a that partitions the vertical block group B in the two central rows.
and 2b have a plant form 5 formed by raising the bottom of the groove.

As shown in FIG. 2, the platform 5 is lower than the height H from the bottom of the transverse groove of the blocks 3a and 3b on both sides, and the top of the platform 5 is in contact with the ground below the ground contact surface during load rolling of the tire. It is raised over the entire width of the transverse groove, leaving a gap W to the extent that it is virtually closed to the side walls of the blocks 3a and 3b on both sides under the contact surface of the tire during load rolling. Note that it is of course possible to install the platform 5 in the transverse groove 2c.

Here, the height h at platform 5 is Hh:
1 to 2 am and the interval wlIw is 0.5 to 1
．． The platform 5 is preferably in the range of 5 mm.Furthermore, in the illustrated example, the platform 5 is arranged near one opening of the transverse groove 2a or 2b, but it may be arranged in the center of the transverse groove or near the other opening. The installation length is 0.0 of the length of each transverse groove.
A range of 2 to 0.5 times is desirable.

Note that the other structure of the tire according to the present invention may be in accordance with the practice of conventional tires.

In other words, the carcass is made by placing a cord bridle between a pair of bead cores, and winding both ends of the cord around the bead core from the inside of the tire to the outside, and the plies are made of organic fiber cords such as polyester or steel cords. They are arranged in a direction (radial direction) substantially perpendicular to the equatorial plane of the tire.

The belt layer includes at least two belt layers in which non-extensible cords such as steel cords are arranged at an angle of 5 to 25 degrees with respect to the equatorial plane of the tire, and are arranged to intersect with each other.

A relatively flexible side rubber layer with high bending resistance is arranged in the sidewall portion, and an air-impermeable inner liner rubber layer is arranged inside the carcass.

Further, the tread has the above-described tread pattern formed on its surface, and is preferably formed of a rubber layer having a Shore A hardness of 45° to 70°.

(Function) The platform installed in the transverse groove of the tread is virtually closed to the block side walls on both sides under the contact surface when the tire is rolling under load, so the blocks are connected at this part as shown in Figure 3. The block rigidity is equivalent to that of a tread, which improves the block's ground contact and ensures excellent handling stability on wet and dry roads. Furthermore, in addition to securing block rigidity, the installation of the platform reduces the porosity of the tread, making it possible to reduce noise.

Furthermore, the plant form bears the circumferential pulling force that occurs when the tire is rolling under load, and the sum of the pulling forces within the tread remains constant, reducing the pulling force that causes uneven wear, especially on the blocks. The uneven wear resistance is improved.

Furthermore, on icy and snowy roads, the movement of the blocks is restricted in the tread shown in FIG. 3 in which the blocks are connected, so that the shearing force caused by snow is particularly small. On the other hand, if the platform is installed under the ground surface where the tire is rolling under load, with a gap that virtually closes the block walls on both sides, the movement of the block will not be restricted and the degree of freedom of movement will increase. However, the performance on icy and snowy roads is improved, especially since the snow shearing force is increased.

In addition, when installing the platform, the height h
H-h: 1 to 211 m, and the gap W is 0.
It is preferable for the following reason to be in the range of 5 to 1, 5++u++ and to have the installation length in the range of 0.2 to 0.5 times the length of each transverse groove.

In other words, the reason why h is set according to H-h: 1 to 2 ms is because if the height h is lower than this range, the plant form part will not touch the ground and no pulling force will be generated in the circumferential direction during load transfer, so the wear resistance will be improved. This is because there is no hope for improvement. If the height is higher than this range, the platform will make contact with the ground, but the force in the circumferential direction during load transfer will be in the driving direction, making it impossible to alleviate the pulling force on the block and increasing the grounding pressure of the platform. Therefore, it is disadvantageous in that the height h decreases rapidly.

The reason for setting the gap W in the range of 0.5 to 1.5 mm is because if the gap is wider than this range, the block walls will not close together during load transfer, resulting in excessive block movement, which is disadvantageous in terms of wear resistance. Become. If the spacing is narrower than this range, the platform will be greatly restricted by the block wall, making it difficult for the platform to touch the ground during load transfer.

The installation length was chosen to be 0.2 to 0.5 times the length of each transverse groove.If the length exceeds this range, the movement of the block will be restricted, the snow shearing force will be reduced, and the performance on snow will be affected. make worse. Furthermore, if the length is shorter than this range, the platform will lack rigidity and cannot bear the drag in the circumferential direction during load transfer, making it impossible to expect uneven wear resistance to be improved.

(Example) A tire with a tire size of 185 R14BPR was manufactured according to the tread pattern shown in FIG. 1. The circumferential groove of this prototype tire has a width of 7mm and a depth of 12.1w+m, a transverse groove has a width of 5m and a depth of 710.21!1m, and the narrow groove has a width of 0.5m and a depth of 8-. , and the height of the platform installed in the transverse trench is h: 9+am (H-h=1
．． 2mm), gap w: 0. Bypm was extended along the transverse groove for 5 mm (0.26 times the transverse groove length).

In addition, a tire with a similar tread pattern without a platform installed in the transverse groove (conventional example) and a tire with the tread pattern shown in FIG. 3 (comparative example) were also prototyped in the same size.

Note that the widths and depths of the circumferential grooves, transverse grooves, and narrow grooves in these conventional and comparative tires are the same as in the test tires described above.

The results of evaluating these tires in an uneven wear test, a sea road performance test, and an ice and snow road performance test are shown in the table below.

The test was conducted using tire internal pressure: 2.6 kgf/front wheel.
(11" and rear wheels at 4.5kgf/c gloss 2,
The test was conducted with one driver on board, and the evaluation was based on an index with each test result of conventional tires set as 100.

In the uneven wear test, the level difference in the lug due to wear after every 10,000 runs was measured during normal driving at a vehicle speed of 30 to 1,100 k/h on ordinary roads (wet and dry), and the reciprocal of the difference was evaluated. The seaway performance test was conducted on various types of driving (straight stability, lane change performance, cornering performance, wet start performance, wet handling stability) at vehicle speeds of 40 to 80 km/h on general road (wet and dry) test courses. The driver's feeling evaluation and ice and snow road performance test evaluates the driver's feeling during various driving (starting, braking, climbing and cornering) at vehicle speeds of 20 to 60 km/h on a test course on compacted snow roads and waterways. , .

(Effects of the Invention) According to the present invention, it is possible to improve traction performance, especially on ice and snow, without sacrificing performance such as uneven wear resistance and maneuverability on ship routes. An optimal tread pattern can be provided for the tire.

[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 taken along line If-II in FIG. 1, and FIG. 3 is a developed view showing another all-weather tread pattern. 1.1a... Circumferential grooves 3a to 3c... Blocks 4c... Circular narrow grooves E... Tread ends 2a to 2c... Transverse grooves 4a, 4b... Thin grooves 5... Platform B ...Column block group

Claims (1)

[Claims] 1. A plurality of circumferential grooves that have a zigzag shape and extend substantially along the tread circumference, and a plurality of transverse grooves that connect the circumferential grooves or the circumferential grooves and the tread edge. This is a pneumatic tire having a group of longitudinal blocks, and the transverse groove has a platform in which the bottom of the groove is raised to a position lower than the block surfaces on both sides, and the platform is placed under the ground contact surface while the tire is rolling under load. An all-weather pneumatic tire characterized by having a gap that virtually closes with the block walls on both sides and a height such that the top portion touches the ground.