JP2005162078A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of improving an on-ice braking performance at an early stage of abrasion without deteriorating a general performance. <P>SOLUTION: This pneumatic tire has a plurality of blocks 4 blocked by a vertical groove 2 and a horizontal groove 3 at a tread part 1. A shallow groove 6 is provided along an edge of the block 4 on a tread face of the block 4. Width W of the shallow part 6 is within a range of 1.0-5.0 mm, depth D of the shallow groove 6 is within a range of 0.2-2.0 mm, and a total edge length per block of the shallow groove 6 is within a range of 50-300% of the peripheral edge length of the block 4 including the shallow groove 6. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire for winter in which a sipe is provided in a block, and more particularly to a pneumatic tire that improves braking performance on ice in the early stage of wear without lowering general performance.

  In general, it has been pointed out that studless tires cannot exhibit sufficient braking performance on ice until the surface layer of the block is peeled off. A lot of mileage is needed to demonstrate.

Therefore, in order to improve the braking performance on ice at the early stage of wear, it has been proposed to perform riblet processing on the tread surface of the block (see, for example, Patent Document 1). When riblet processing is applied to the tread surface of the block, it is possible to promote initial wear and improve drainage. However, in the case of heavy-duty tires with high surface pressure on the block, general performance such as dry performance and wet performance at the initial stage of wear is greatly reduced due to the influence of riblet processing, and these general performance and braking performance on ice must be compatible. Is difficult.
Japanese Patent Laid-Open No. 7-186633

  An object of the present invention is to provide a pneumatic tire capable of improving the braking performance on ice in the early stage of wear without degrading the general performance.

  The pneumatic tire of the present invention for achieving the above object is a pneumatic tire having a plurality of blocks partitioned by grooves in the tread portion, and provided with shallow grooves along the edges of the blocks on the tread surface of the blocks, The width W of the shallow groove is in the range of 1.0 to 5.0 mm, the depth D of the shallow groove is in the range of 0.2 to 2.0 mm, and the total edge length per block of the shallow groove The length L is in the range of 50 to 300% of the edge length around the block including the shallow groove.

  In particular, the interval P between the edge of the block and the portion along the block edge of the shallow groove is preferably in the range of 2.5 to 10.0 mm.

  In the present invention, a shallow groove is provided on the tread surface of the block along the edge of the block, the width W and the depth D of the shallow groove are defined, and the total edge length L per block of the shallow groove is defined. More preferably, the interval P between the edge of the block and the portion along the block edge of the shallow groove is defined, and as a result, the edge of the shallow groove and the edge of the block are arranged in a contour line, thereby improving the general performance. It is possible to improve the braking performance on ice at the initial stage of wear while suppressing the decrease to the minimum.

  The shallow groove functions more effectively when the surface pressure applied to the block is high. Therefore, when the present invention is applied to a heavy duty pneumatic tire, a higher effect can be obtained.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows a tread pattern of a winter pneumatic tire according to an embodiment of the present invention, and FIGS. 2 and 3 show blocks of the pneumatic tire.

  As shown in FIG. 1, a plurality of vertical grooves 2 extending in the tire circumferential direction and a plurality of horizontal grooves 3 extending in the tire width direction are formed in the tread portion 1, and the vertical grooves 2 and the horizontal grooves 3 A plurality of blocks 4 are partitioned. Each block 4 is formed with a plurality of sipes 5 extending in the tire width direction. These sipes 5 contribute to the improvement of braking performance on ice by the edge effect.

  As shown in FIGS. 2 and 3, shallow grooves 6 extending in an annular shape along the edge of the block 4 are formed on the tread surface of the block 4. The width W of the shallow groove 6 is set in the range of 1.0 to 5.0 mm, the depth D of the shallow groove 6 is set in the range of 0.2 to 2.0 mm, and the total per block of the shallow groove 6 is set. The edge length L is set in the range of 50 to 300%, preferably 150 to 250% of the edge length around the block 4 including the shallow groove 6. However, the total edge length L per block of the shallow groove 6 is the total length of the edges of both groove walls of the shallow groove 6, and the edge length around the block 4 is the block contour line on the tread surface. Length. Furthermore, it is desirable that the distance P between the edge of the block 4 and the portion along the block edge of the shallow groove 4 (portion extending in a ring shape along the block edge) is in the range of 2.5 to 10.0 mm.

  Thus, by providing the shallow groove 6 along the edge of the block 4 on the tread surface of the block 4 and arranging the edge of the shallow groove 6 and the edge of the block 4 in a contour line, the deterioration in general performance is minimized. It is possible to improve the braking performance on ice at the initial stage of wear.

  Here, if the width W of the shallow groove 6 is less than 1.0 mm or the depth D thereof is less than 0.2 mm, the shallow groove 6 is crushed at the time of grounding, and an effective edge effect is obtained. Disappear. Even when the width W of the shallow groove 6 exceeds 5.0 mm, the shallow groove 6 is similarly crushed and an effective edge effect cannot be obtained. On the other hand, when the depth D of the shallow groove 6 exceeds 2.0 mm, the braking performance and steering stability on the general road surface will be reduced.

  Further, if the total edge length L per block of the shallow groove 6 is less than 50% of the edge length around the block 4, the effect of improving the braking performance on ice at the initial stage of wear becomes insufficient, and conversely 300% Exceeding will cause a reduction in braking performance and steering stability on general road surfaces. In addition, when the distance P between the edge of the block 4 and the portion along the block edge of the shallow groove 6 is less than 2.5 mm, the braking performance and steering stability on the general road surface are deteriorated, and conversely exceeds 10.0 mm. In addition, the effect of improving the braking performance on ice at the initial stage of wear becomes insufficient.

  If the shallow groove 6 is arranged in only one of the vertical direction and the horizontal direction, the steering stability and braking performance on the general road surface may be deteriorated when sufficiently improving the braking performance on ice. Become. Therefore, the shallow groove 6 needs to be arranged along the edge of the block 4 so as to include the longitudinal and lateral extension components. However, the arrangement form of the shallow grooves 6 is not limited to the above embodiment, and various forms can be adopted.

  4A to 4F show a modification of the shallow groove. 4 (a) and 4 (b), the shallow groove 6 extends along the edge of the block 4 and includes vertical and horizontal extension components, but is partially interrupted. 4C to 4F, the shallow groove 6 includes one or more openings 6a that are opened in the side wall of the block 4. It is advantageous in terms of rigidity that the shallow groove 6 does not have the opening 6a. However, the shallow groove 6 may have an opening 6a communicating with the vertical groove 2 or the horizontal groove 3 for the purpose of discharging moisture scraped off from the road surface. .

  In a pneumatic tire having a tire pattern of 195 / 85R16 114 / 112L and having a block pattern and a plurality of sipes in each block, a conventional example in which shallow grooves are not provided in the tread of the block, and a tread on the tread of the block A shallow groove is provided along the edge of the block, the width W of the shallow groove, the depth D of the shallow groove, the ratio of the total edge length L per block of the shallow groove to the edge length around the block, the edge of the block Tires of Examples 1 to 4 and Comparative Examples 1 to 4 having different intervals P between the groove and the portion along the block edge of the shallow groove were manufactured.

  With respect to these test tires, braking performance on ice, braking performance on a dry road surface, and steering stability on a dry road surface were evaluated by the following test methods, and the results are shown in Table 1.

Ice braking performance:
The test tire was mounted on a small truck under conditions of a rim size of 16 × 5 1 / 2K and an air pressure of 600 kPa, and braking was performed from a traveling state at a speed of 40 km / h on a frozen road surface, and the braking distance was measured. The measurement of the braking distance was performed immediately after wearing and after traveling 1000 km. The evaluation results are shown as an index using the reciprocal of the measured values, with the measurement results after traveling 1000 km of the conventional example being 100. The larger the index value, the better the braking performance on ice.

Brake performance on dry roads:
The test tire was mounted on a small truck under conditions of a rim size of 16 × 5 1 / 2K and an air pressure of 600 kPa, and braking was performed from a traveling state at a speed of 50 km / h on a dry road surface, and the braking distance was measured. The evaluation results are shown as an index with the conventional example being 100, using the reciprocal of the measured value. The larger the index value, the better the braking performance on the dry road surface.

Steering stability on dry roads:
The test tire was mounted on a small truck under the conditions of a rim size of 16 × 5 1 / 2K and an air pressure of 600 kPa, and the feeling of the panel was evaluated on a dry road surface. The evaluation results are shown as an index with the conventional example being 100. The larger the index value, the better the steering stability on the dry road surface.

  As can be seen from Table 1, the tires of Examples 1 to 4 can exhibit on-ice braking performance equivalent to that in the middle wear after running for 1000 km in the initial wear immediately after being mounted, and also the braking performance on the dry road surface and maneuvering. About stability, it was possible to ensure the same level as before. On the other hand, the tires of Comparative Examples 1 and 2 are insufficient in improving the braking performance on ice, and the tires of Comparative Examples 3 and 4 have greatly reduced braking performance and driving stability on dry road surfaces compared to the conventional examples. It was.

It is an expanded view which shows the tread pattern of the winter pneumatic tire which consists of embodiment of this invention. It is a perspective view which shows the block of the pneumatic tire of FIG. It is XX arrow sectional drawing of FIG. (A)-(f) is a perspective view which shows the various form of the block which provided the shallow groove | channel.

Explanation of symbols

1 Tread part 2 Vertical groove 3 Horizontal groove 4 Block 5 Sipe 6 Shallow groove

Claims (2)

In the pneumatic tire having a plurality of blocks partitioned by grooves in the tread portion, shallow grooves are provided along the edges of the blocks on the tread surface of the blocks, and the width W of the shallow grooves is 1.0 to 5.0 mm. The depth D of the shallow groove is in the range of 0.2 to 2.0 mm, and the total edge length L per block of the shallow groove is the edge length around the block including the shallow groove. Pneumatic tire in the range of 50 to 300%. The pneumatic tire according to claim 1, wherein a distance P between the edge of the block and a portion along the block edge of the shallow groove is in a range of 2.5 to 10.0 mm.

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