JP2006327245A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of enhancing the running performance on a dry road surface while keeping the running performance on an ice covered road surface during the brand-new one. <P>SOLUTION: The pneumatic tire is structured so that a plurality of lands consisting of blocks 4 and/or ribs are formed on the tread surface 1 and a plurality of parallel shallow grooves 5 having a depth and width of 0.1-0.8 mm are formed at the surfaces of the lands, wherein the density of groove arrangement of the shallow grooves 5 in the peripheral area 4b of each land on at least one side thereof in the tire width direction and/or circumferential direction is made coarser than that of the central area 4a except the peripheral areas 4b, or otherwise the grooves 5 are arranged in the tire circumferential direction or across the width and also the intervals of the grooves 5 being arranged widen in steps from the central part of the land toward the two ends. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire in which initial running performance is further improved in a tire provided with a number of shallow grooves on a tread surface in order to improve running performance when new.

  In general, the tread surface of a new tire is mirror-finished by a vulcanization mold, and at the same time, the mold release agent applied to the mold penetrates and the surface is smoothly formed. Since the desired running performance cannot be obtained at the initial stage of running, there is a problem that the running must be done until the tread surface is worn to some extent and the desired running performance is exhibited.

As a measure to supplement the running performance at the initial stage of the running, a large number of shallow grooves with a groove depth and a groove width of about 0.1 to 0.8 mm are provided on the block surface so as not to disappear during the running-in. (See, for example, Patent Documents 1 and 2). However, if such a shallow groove is provided on the block surface, the ground contact area and surface rigidity of the block are reduced, so depending on the arrangement form of the shallow groove, the running performance is lowered, and there is still room for improvement. .
Japanese Patent No. 3017677 JP 2004-34903 A

  An object of the present invention is to solve the above-mentioned conventional problems, and to further improve the initial running performance in a tire provided with a number of shallow grooves on the tread surface in order to improve running performance when new. Is to provide a pneumatic tire.

  In order to achieve the above object, the pneumatic tire of the present invention forms a plurality of land portions made of blocks and / or ribs on the tread surface, and has a groove depth and a groove width of 0.1 to 0.1 on the surface of these land portions. In the pneumatic tire in which a plurality of parallel shallow grooves to be 0.8 mm are arranged, (1) the arrangement density of the shallow grooves in the peripheral region on at least one side in the tire width direction and / or the circumferential direction of the land portion. , Sparser than the arrangement density in the central area excluding the peripheral area, or (2) The shallow grooves are arranged in the tire circumferential direction or the width direction, and the arrangement interval of the shallow grooves is changed from the central part of the land part. The gist is that it is formed so as to expand stepwise toward both ends.

  According to the present invention, the arrangement density of the shallow grooves in the peripheral area on at least one side in the tire width direction and / or the circumferential direction on the surface of the land portion composed of blocks and / or ribs is arranged in the central area excluding the peripheral area. Density is less than the density, or shallow grooves are arranged in the tire circumferential direction or the width direction, and the arrangement interval of the shallow grooves is formed so as to expand stepwise from the center portion to both ends of the land portion. Therefore, when driving on wet roads, it is possible to quickly drain the central area or water film in the central part where drainage is difficult to improve and improve wet driving performance. Therefore, the steering stability can be improved by the peripheral area extending in the tire circumferential direction, and the braking / driving performance can be improved by the peripheral area extending in the tire width direction.

  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, and FIG. 2 is an enlarged plan view showing a block of the tire shown in FIG.

  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 form a large number of blocks 4.

  A plurality of parallel shallow grooves having a groove depth and a groove width of 0.1 to 0.8 mm are formed on the surface of each block 4 constituting the four block rows on the central side excluding the block rows on both shoulder sides. 5 is formed. As shown in FIG. 2, the arrangement density of the shallow grooves 5 on the surface of the block 4 is different between the central area 4a and the peripheral area 4b of the block 4, and is dense in the central area 4a and sparse in the peripheral area 4b. Are arranged as follows.

  As a result, when driving on a wet road surface, the shallow groove 5 in which the water film in the central area 4a of the block 4 that is difficult to drain can be drained quickly to improve the wet driving performance and to drive on the dry road surface. In some cases, a decrease in rigidity in the peripheral region 4b is suppressed, so that the steering stability can be improved by the peripheral region 4b extending in the tire circumferential direction, and the braking / driving performance can be improved by the peripheral region 4b extending in the tire width direction.

  As described above, the groove depth and groove width of the shallow groove 5 formed on the surface of the block 4 in the pneumatic tire of the present invention are set to 0.1 to 0.8 mm, more preferably groove depth. The thickness and the groove width may be set to 0.2 to 0.5 mm. Thereby, wet running performance and dry running performance can be improved with a better balance.

  In the present invention, as shown in FIG. 1 and FIG. 2, the arrangement density of the shallow grooves 5 on the surface of the block 4 is formed so as to be sparse in the peripheral area 4b in the front, rear, left, and right sides of the block 4. ) Or (b), and further, as illustrated in FIG. 4 (a) or (b), one or both of the block 4 in the tire width direction X and / or the circumferential direction Y is defined as a peripheral area 4b. In the region 4b, the shallow grooves 5 can be arranged so as to be sparse.

  That is, in FIG. 3A, the left and right sides in the tire width direction X are the peripheral areas 4b, and in FIG. 3B, the front and rear sides in the tire circumferential direction Y are the peripheral areas 4b, and the shallow grooves 5 are sparse in these peripheral areas 4b. It is arranged to be. In FIG. 4A, one side (right side in the figure) in the tire width direction X is a peripheral area 4b, and in FIG. 4B, one side (lower side in the figure) in the tire circumferential direction Y is the peripheral area. As 4b, it arrange | positions so that the shallow groove | channel 5 may become sparse in these peripheral areas 4b.

  In the above-described embodiment, the case where the land portion formed on the tread surface 1 is the block 4 has been described, but the land portion formed on the tread surface 1 may be formed of a rib extending in the tire circumferential direction Y. In this case, at least one side of the rib in the tire width direction X is a peripheral area, and the shallow grooves 5 are arranged so as to be sparse in the peripheral area.

  In the present invention, the area occupied by the central area and the peripheral area of the land portion is different depending on the form of the pattern and the shape of the land portion. The length in the width direction X and / or the circumferential direction Y is determined as a region that occupies 30 to 90%, more preferably 45 to 70% of the length of the block 4 in the tire width direction X and / or the circumferential direction Y, respectively. Good. Further, the central region 4a in the case where the land portion is constituted by ribs may be determined as a region that occupies 30 to 90%, more preferably 45 to 70% of the length of the rib in the tire width direction. And the area | region remove | deviated from the center area | region 4a mentioned above is set as the peripheral area | region 4b.

  The groove area ratio of the shallow groove 5 in the above-mentioned land portion is 15 to 50%, more preferably 20 to 40% in the central region 4a, and 10 to 40%, more preferably 15 to 30% in the peripheral region 4b. It is good to adjust. Thereby, wet running performance and dry running performance can be improved with good balance.

  In addition, the arrangement interval of the shallow grooves 5 in the present invention may be set to 0.5 to 2.0 mm, most preferably 0.7 to 1.4 mm. If the distance between the shallow grooves 5 is less than 0.5 mm, sufficient running performance on a wet road surface cannot be obtained, and if it exceeds 2.0 mm, the rigidity of the block 4 is too low and the running performance on a dry road surface is lowered. .

  Furthermore, it is preferable that at least one end of the shallow groove 5 formed in the central region 4a of the land portion is communicated with the vertical groove 2 or the horizontal groove 3 that partitions the land portion. Thereby, the drainage property in the central area 4a of a land part is ensured, and the traveling performance on a wet road surface can be improved more reliably.

  The planar form of the shallow groove 5 in the present invention is not limited to the straight groove extending linearly, but can be formed in a wave shape or a zigzag shape. Further, the inclination direction of the shallow groove 5 is not limited to the above-described embodiment, but may be crossed in the central region 4a as illustrated in FIG. 5A, or illustrated in FIGS. 5B and 5C. It may be formed so as to extend in the tire width direction X or the circumferential direction Y (circumferential direction Y in the figure).

  FIGS. 6A and 6B are plan views showing the arrangement of the shallow grooves 5 formed in the land portion according to another embodiment of the present invention, and the groove depth and the surface of the block 4 constituting the land portion are shown in FIG. A plurality of shallow grooves 5 having a groove width of 0.1 to 0.8 mm are arranged in parallel to the tire circumferential direction or the width direction, and these shallow grooves 5 are spaced from the central portion of the block 5 toward both ends. Arranged in stages. By arranging the shallow grooves 5 in this way, the same operational effects as the block 5 shown in FIGS. 3A and 3B described above can be obtained.

  In the embodiment described above, the case where the planar shape of the block 4 formed on the tread surface 1 is a vertically long rectangular shape has been described, but the planar shape of the block 4 in the pneumatic tire of the present invention is limited to a rectangular shape. In some cases, it may be formed in an arbitrary shape. Therefore, the boundary line Q shown in FIG. 2 that divides the central area 4a and the peripheral area 4b of the block 4 in such a case is represented by a boundary line similar to the outer edge line of the block 4. That is, when the planar form of the block 4 is as shown in FIG. 7A or 7B, the boundary line Q described above is a boundary line Q inside the block 4 similar to the outer edge line of the block 4 as shown in the figure. And at least one side of the front, rear, right and left with the boundary line Q as a boundary is defined as a peripheral region 4b, and the shallow grooves 5 are sparsely disposed in the peripheral region 4b.

  Since the present invention described above is an invention as a temporary measure to supplement the running performance until the tread surface 1 is worn to some extent and the desired running performance is exhibited, it is formed on the surface of the land portion. The shallow groove 5 disappears through the running-in of the new tire. Therefore, the present invention is preferably applied to a studless tire or an all-season tire in which a plurality of sipes extending in the tire width direction are formed on the land portion.

  The tire size (195 / 65R15), tread pattern (FIG. 1), and tire specifications are the same, and the groove spacing is made tight on the entire surface of each block 4 constituting the four block rows on the center side of the tread surface in FIG. The conventional tire (conventional example) in which the shallow grooves are formed, and the shallow groove spacing in the peripheral region 4b is made sparse, and the longitudinal direction (circumferential direction) and lateral direction (width direction length of each block 4) Thus, tires of the present invention (Examples 1 to 9) in which the ratio (%) occupied by the length of the central region 4a was varied as shown in Table 1. The depth of the shallow groove was 0.3 mm, The width is common to 0.32 mm, and the groove area ratio of the shallow grooves in each block 4 is shown as follows: In Table 1, the central region 4a has a length in the circumferential direction and width direction of the block 4. The ratio (%) that the length occupies is "around (%) x width (%)" It displayed Te.

[Slot area ratio of shallow grooves]
・ Conventional tire: All areas = 36%
-Tire of the present invention: central area 4a = 36%, peripheral area 4b = 18%
For these 10 types of tires, braking performance on wet road surfaces, steering stability performance on dry road surfaces, driving performance and braking performance were evaluated by the following methods, respectively, and the results are shown in Table 1 by index display with the conventional example being 100. Also written. The larger the value, the better.

[Brake performance on wet road] (referred to as braking performance on ice in Table 1)
Each tire was filled with an air pressure of 200 kPa and mounted on a vehicle (domestic FR car, 2000 cc), and the braking distance was measured by ABS braking at a braking speed of 40 km / h on the road surface on ice.

[Operation stability on dry road surface] (referred to as DRY operation performance in Table 1)
Each tire is filled with air pressure 200kPa and mounted on a vehicle (domestic FR car, 2000cc). A test course consisting of an asphalt road is run, and a sensory evaluation of steering stability is performed by a skilled test driver. Based on the evaluation.

[Driving performance on dry road] (referred to as DRY driving performance in Table 1)
Each tire is filled with air pressure 200 kPa and mounted on a vehicle (domestic FR car, 2000 cc), and the driving performance is measured by measuring the time required to reach 20 km / h to 100 km / h on a test course consisting of asphalt road surface. Was evaluated and evaluated based on the results.

[Brake performance on dry road surface] (referred to as DRY braking performance in Table 1)
Each tire is filled with air pressure 200kPa and mounted on a vehicle (domestic FR car, 2000cc), and the braking distance is measured by ABS braking at an initial speed of 100km / h on a test course consisting of asphalt road surface to evaluate the braking performance. And evaluated based on the results.

  From Table 1, it can be seen that the tire of the present invention improves the steering stability performance, the driving performance, and the braking performance on the dry road surface with almost no decrease in the braking performance on the wet road surface compared with the conventional tire.

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. FIG. 2 is an enlarged plan view showing the tire block of FIG. 1 taken out. (A) And (b) is an enlarged plan view equivalent to FIG. 2 of the block which consists of other embodiment of this invention. (A) And (b) is an enlarged plan view equivalent to FIG. 2 of the block which consists of further another embodiment of this invention. (A)-(c) is an enlarged plan view equivalent to FIG. 2 of the block which consists of further another embodiment of this invention. (A) And (b) is an enlarged plan view equivalent to FIG. 2 of the block which consists of further another embodiment of this invention. (A) And (b) is a top view for demonstrating the arrangement | positioning form of the shallow groove | channel formed in a block.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tread surface 2 Vertical groove 3 Horizontal groove 4 Block 4a Central area 4b Peripheral area 5 Shallow groove X Tire width direction Y Tire circumferential direction Q Boundary line

Claims (7)

Air in which a plurality of land portions composed of blocks and / or ribs are formed on the tread surface, and a plurality of parallel shallow grooves having a groove depth and a groove width of 0.1 to 0.8 mm are arranged on the surface of these land portions. In entering tires,
A pneumatic tire in which the arrangement density of the shallow grooves in the peripheral area on at least one side in the tire width direction and / or the circumferential direction of the land portion is sparser than the arrangement density in the central area excluding the peripheral area.   2. The pneumatic tire according to claim 1, wherein a central area in the land portion occupies 30 to 90% of a length in the tire width direction and / or a circumferential direction of the land portion.   The pneumatic tire according to claim 1 or 2, wherein a groove area ratio of the shallow groove in the land portion is 15 to 50% in the central region, 10 to 40% in the peripheral region, and smaller than the central region. .   The pneumatic tire according to claim 1, wherein an interval between the shallow grooves is 0.5 to 2.0 mm.   The pneumatic tire according to any one of claims 1 to 4, wherein at least one end of the shallow groove in the central region communicates with a groove that defines the land portion. Air in which a plurality of land portions composed of blocks and / or ribs are formed on the tread surface, and a plurality of parallel shallow grooves having a groove depth and a groove width of 0.1 to 0.8 mm are arranged on the surface of these land portions. In entering tires,
A pneumatic tire in which the shallow grooves are arranged in the tire circumferential direction or the width direction, and the interval between the shallow grooves is formed so as to gradually expand from the center portion of the land portion toward both end portions. The pneumatic tire according to any one of claims 1 to 6, which is a studless tire or an all-season tire provided with a plurality of sipes extending in the tire width direction in the land portion.

Images