JP4735137B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire that ensures traveling performance when new.

  Generally, rubber for maintaining running performance is used for a tire tread, and a groove for exhibiting running performance is formed on the tread surface. However, the tread surface of a tire when it is new is finished with a mirror-like surface by a vulcanization mold, and at the same time, the release agent applied to the mold penetrates and the surface is formed smoothly. There is a problem that desired running performance cannot be secured at the initial stage of tire running.

  In particular, studless tires designed to improve driving performance on icy road surfaces have tread surfaces formed into block pans and a number of narrow grooves (sipes) formed on the block surface. The water film removal effect is used to ensure the driving performance on the frozen road surface, but since the frictional force on the frozen road surface is insufficient at the initial stage of tire driving, the performance on ice cannot be obtained. It must be conditioned until the original tread rubber is exposed due to wear and the desired performance on ice is achieved.

As a countermeasure, in order to compensate for the performance degradation at the initial stage of running, a number of shallow grooves having a depth of about 0.1 to 0.8 mm in parallel with the groove depth shallower than the above-mentioned narrow groove (sipe) are formed on the block surface. There is a proposal to compensate for the running performance in the early running by the edge effect (see, for example, Patent Documents 1 and 2). However, simply forming such a shallow groove on the block surface does not necessarily compensate for the running performance comparable to that when the original tread rubber is exposed.
Japanese Patent No. 3017677 JP 2004-34903 A

  An object of the present invention is to solve the above-described conventional problems, and to provide a pneumatic tire that ensures traveling performance when new.

In order to achieve the above object, a pneumatic tire according to the present invention has a land portion composed of a plurality of block rows and / or rib rows extending in the tire circumferential direction on a tread surface, and a groove depth and a surface on the surface of these land portions. In a pneumatic tire in which a plurality of linearly extending shallow grooves having a groove width of 0.1 to 0.8 mm are formed, the angle of the shallow grooves with respect to the tire circumferential direction is set to 25 to 80% of the contact width of the tread surface. a land portion of the central region which corresponds to, Rutotomoni was different between the land portion of the shoulder area with the exception of the central area, on one side sandwiching the tire equator line of the tread surface, the inclination direction of the shallow groove formed in the land portion Are formed in opposite directions between adjacent land portions, and the angle in the land portion of the shoulder region is larger than the angle in the land portion of the central region.

According to the present invention, the angle of the shallow groove extending linearly with a groove depth and groove width of 0.1 to 0.8 mm formed on the surface of the land portion with respect to the tire circumferential direction affects the drainage. a land portion of the central region which corresponds to 25-80% of the ground contact width of the surface, Rutotomoni made different between the land portion of the impact shoulder area in braking performance on both sides, one side sandwiching the tire equator line of the tread surface , formed in opposite directions between the land portions adjacent the inclination direction of the shallow groove formed in the land portions, and since the increase in the land portion of the shoulder area small at the land portion of the central region of the angle of the shallow grooves, the vehicle Regardless of the installation position, the drainage effect based on the shallow groove in the central land area maintains the steering stability performance, while the shallow groove in the shoulder area improves the braking performance. Driving performance can be further improved

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a partial plan view showing an example of a tread surface of a pneumatic tire according to an embodiment of the present invention.

  In FIG. 1, the pneumatic tire is provided with a plurality of vertical grooves 2 extending in the tire circumferential direction Y and a plurality of horizontal grooves 3 extending in the tire width direction X intersecting with the tread surface 1. 3, a land portion composed of a plurality of (6 in the figure) block rows 4a, 4b, 4c, 4d, 4e, and 4f extending in the tire circumferential direction Y is formed.

On the surface of each block 4 constituting these block rows 4a, 4b, 4c, 4d, 4e, and 4f, as shown in the figure, a plurality of linear shapes with a groove depth and a groove width of 0.1 to 0.8 mm are formed. An extending shallow groove 5 is formed. The angle of the shallow grooves 5 formed on the surface of each block row with respect to the tire circumferential direction corresponds to 25 to 80%, preferably 50 to 75% (approximately 67% in the figure) of the contact width W of the tread surface 1. The block rows 4b, 4c, 4d and 4e arranged in the central area P are different from the block rows 4a and 4f arranged in the shoulder areas Q and Q excluding the central area P on both sides thereof, and the shoulder areas Q and Q The angle β in the block rows 4a, 4f is set to be larger than the angle α in the block rows 4b, 4c, 4d, 4e in the central area. That is, in the tire of FIG. 1, the relationship between the angles α and β of the shallow groove 5 with respect to the tire circumferential direction is α <β.

As described above, by making the angle β at the land portions 4a, 4f of the shoulder regions Q, Q larger than the angle α at the land portions 4b, 4c, 4d, 4e of the central region P, the land portion 4b of the central region P is obtained. 4c, 4d, 4e While maintaining the steering stability performance due to the drainage effect based on the shallow grooves 5, the braking performance is improved by the shallow grooves 5 in the land portions 4a, 4f of the shoulder areas Q, Q. Driving performance can be further improved.
Furthermore, in the present invention, the inclination direction of the shallow groove 5 formed in each land portion 4a, 4b, 4c, 4d, 4e, 4f is set between the adjacent land portions on one side of the tread surface 1 across the tire equator line CL. They are formed in opposite directions. As a result, it is possible to efficiently improve the running performance when new, regardless of the mounting position on the vehicle.

  In addition, although the case where the land part was comprised by the six block row | line | column which consists of block row | line | columns 4a, 4b, 4c, 4d, 4e, 4f was shown in FIG. 1, the number of the land parts formed in the tread surface 1 Is not limited to this. Accordingly, the land portion formed on the tread surface 1 may be disposed on the tire equator line CL. Further, each land portion is not limited to a block row, and may be configured by including a rib row in the land portion.

  In the present invention, the angle α with respect to the tire circumferential direction of the shallow groove 5 formed in the land portion of the central region P is set to 0 to 50 °, preferably 25 to 45 °, and formed in the land portions of the shoulder regions Q and Q. The angle β of the shallow groove 5 with respect to the tire circumferential direction may be set to 50 to 90 °, preferably 65 to 85 °. Thereby, drainage property and braking performance can be maintained with good balance.

In the pneumatic tire of the present invention, the groove depth and groove width of the linearly extending shallow groove 5 formed on the surface of each land portion are set to 0.1 to 0.8 mm, more preferably the groove depth. The thickness and the groove width may be set to 0.2 to 0.5 mm. Thereby, drainage property and braking performance can be improved with a better balance.

  In the present invention, the interval between the shallow grooves 5 formed in each block row is preferably set to 0.5 to 2.0 mm. If the distance between the shallow grooves 5 is less than 0.5 mm, the ground contact area of the land portion will be insufficient and steering stability and drivability will deteriorate, and if it exceeds 2.0 mm, drainage will deteriorate and good steering stability will be achieved. It becomes difficult to secure.

  The pneumatic tire of the present invention described above is preferably applied to a winter tire in which a plurality of sipes extending in the tire width direction are formed on the surface of each land portion. The pneumatic tire configured as described above can be widely applied as a studless tire because it can improve the braking performance while maintaining the steering stability performance on the frozen road surface when new.

The tire size (195 / 65R15), the tread pattern (FIG. 1) and the sipe extending in the tire width direction are formed on the block surface, and the shallow groove (depth = 0.3 mm, formed on each block surface). Conventional tires (conventional examples), tires of the present invention (Examples 1 to 3 ), and comparative tires (comparative), in which the angles with respect to the tire circumferential direction of the width = 0.32 mm and interval = 1.0 mm are different as shown in Table 1. Examples 1, 2) were prepared.

For these six types of new tires, the steering stability performance and braking performance on the road surface on ice were evaluated by the following methods, respectively, and the results are also shown in Table 1 by index display with the conventional example as 100. The larger the value, the better.

[Maneuvering stability]
Each new tire was filled with an air pressure of 200 kPa and mounted on a domestic 2000cc FR vehicle. A test course consisting of an ice board road surface was run, and a sensory evaluation of steering stability was performed by a skilled test driver, and the evaluation was made based on the results.

[Brake performance]
Each new tire was filled with an air pressure of 200 kPa and mounted on a domestic 2000 cc FR vehicle, and the braking distance was measured by ABS braking from 40 km / h on a test course consisting of an ice board road surface.

  From Table 1, it can be seen that the tire of the present invention improves the driving performance while maintaining the steering stability performance on the road surface on ice when new, compared with the conventional tire and the comparative tire. In addition, although the tire of Example 3 is slightly disadvantageous in terms of steering stability performance, it is at a level that meets the object of the present invention.

It is a partial top view which shows an example of the tread surface of the pneumatic tire which consists of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tread surface 2 Vertical groove 3 Horizontal groove 4 Block 4a, 4b, 4c, 4d, 4e, 4f Block row 5 Shallow groove X Tire width direction Y Tire circumferential direction W Ground contact width P Center area Q Shoulder area

Claims (4)

A plurality of straight lines in which a land portion composed of a plurality of block rows and / or rib rows extending in the tire circumferential direction is arranged on the tread surface, and a groove depth and a groove width are set to 0.1 to 0.8 mm on the surface of these land portions. In a pneumatic tire formed with a shallow groove extending in a shape ,
Wherein an angle with respect to the tire circumferential direction of the shallow groove, made different in the land portion of the central region which corresponds to 25-80% of the contact width of the tread surface, the land portion of the shoulder area except the central region Rutotomoni, wherein On one side of the tire equator line on the tread surface, the shallow groove formed in the land portion is inclined in the opposite direction between the adjacent land portions, and the angle in the land portion of the shoulder region is the center region. A pneumatic tire that is larger than the above-mentioned angle in the land portion.   The pneumatic tire according to claim 1, wherein the angle in the land portion of the central region is 0 to 50 °, and the angle in the land portion of the shoulder region is 50 to 90 °. The pneumatic tire according to claim 1 or 2, wherein a distance between the shallow grooves is 0.5 to 2.0 mm. The pneumatic tire according to claim 1, 2, or 3, wherein the tire is a winter tire in which a plurality of sipes extending in a tire width direction are formed on a surface of the land portion.

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