JPH0532243B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Field of Application) The technical contents described in this specification regarding tire patterns with high wet skid resistance are mainly for passenger cars, and in particular, the tire pattern with high wet skid resistance is mainly applied to passenger cars. A tread surface pattern that advantageously overcomes the problem of wet skid resistance due to worsening of water drainage in the central contact area of the tire when the ground contact width on the running road surface is wide due to the small tonnage ratio or large size. In other words, it relates to the improvement of tire patterns and is located in the field of technology to which the above-mentioned passenger tires belong. Since the development of radial carcass structure tires, the flattened ratio of tires has been rapidly decreasing.
As a result, the ground contact width of the tread portion has been relatively significantly expanded. Flat tires are generally particularly advantageous in terms of maneuverability during high-speed driving, but the expansion of the ground contact width described above is due to the increased grip on the road surface due to running or standing water on the road surface due to rainfall, which should be encountered even during high-speed driving. This is disadvantageous in avoiding deterioration of performance because the drainage path for water drainage from the center area of the tire's contact with the ground to the sides becomes long, causing the tire to contact the road surface while running at high speed. When a water film of a thickness exhibiting a so-called fluid lubrication effect is formed between the tread and the tread, there is a risk that the steering function of the vehicle will be lost due to the aquaplaning phenomenon. (Prior Art) Recent trends in promoting drainage of the torpedo contact area during high-speed running on rain-wet tracks have been developed, rather than in racing, as disclosed, for example, in Japanese Patent Application Laid-Open No. 57-194106. The aim is to eliminate the need for replacement tires due to sudden changes in weather during races, and to this extent, even if it is related to the purpose of development unique to race tires, multiple pairs of tires parallel to each other across the center circumference of the tread section are used. The vertical grooves are narrower and shallower as they are farther from the plane containing the circumference, and diagonal grooves that intersect with these to form a mesh groove are formed at the tread edge at an angle of about 75° or less with respect to the plane containing the central circumference. Particularly noteworthy is the reference to the suitability of directional tires, which also have an angle of less than approximately 40° in the center of the tread, directing water as much as possible in the direction of natural flow. However, in this case, apart from the above-mentioned unique usage of the tire, under the conditions of use of a general tire, the steeply diagonal arrangement of the diagonal grooves as described above, the sharp corners of the diamond-shaped blocks in the center of the tread. In particular, since the groove depth is the maximum, there are concerns about so-called block chipping and localized abnormal wear, making it difficult to put it to practical use. (Problem to be Solved by the Invention) Therefore, a type of passenger car that provides a wide ground contact with the running road surface by effectively increasing the drainage capacity, especially in the central region of the tread section, without having the above-mentioned disadvantages. It is an object of this invention to provide a tire with a matched tread pattern. (Means for Solving the Problems) The above objects of the invention can be advantageously achieved by a system based on the following matters. The tread portion has a tread portion that makes contact with the ground over a wide width, and this tread portion has a pair of central longitudinal grooves extending parallel to each other across the central circumference, and grooves extending from the side ends of the tread portion of these central longitudinal grooves. Each gap is divided into two, and a pair of side longitudinal grooves also extending in parallel are provided as tread main grooves, and a large number of lateral grooves are arranged diagonally in a herringbone pattern across these tread main grooves. In combination with the tread main groove, each transverse groove forms a block-type pattern that is partitioned independently from each other; Approximately along the fold line that slopes at each intersection angle of a gentle slope within the range of 60 to 90° between the longitudinal groove and the side edge of the tread portion, and a steep slope within the range of 30 to 60° between both longitudinal grooves. A curved shape extending in an S shape or a mirror image S shape and having an inflection point midway between the central circumference of the tread portion and the side edges of the tread portion; For the partial total area of each area divided into three equal parts,
A passenger car tire with high wet skid resistance characterized by an arrangement of the blocks such that the ratio of the total surface area of the blocks occupying the region is minimized in a region near the central circumference of the tread portion. Tortled pattern. (Function) The blocks partitioned independently as described above are arranged obliquely to the tread main groove in a herringbone pattern, and the plane including the central circumference of the tread portion for each section of a large number of lateral grooves is Under a specific intersection angle, the central area and both side areas of the tread part form a parallelogram that is almost rhombic in the middle, but the contour shape is more rectangular, so there is a risk of block chipping or This eliminates the problem of uneven wear, and also minimizes the block surface area ratio in the area close to the center circumference of the area divided into three equal parts between the center circumference of the tread and the side edges of the tread. The maximum drainage capacity is ensured in the central region, leading to an effective improvement in wet skid resistance. The above-mentioned intersection angle of the lateral grooves must form a gentle slope in the range of 60° to 90° between the central circumference of the tread part and the central longitudinal groove and between the side edges of the tread part and the side longitudinal grooves, If the angle is less than 60 degrees, there will be disadvantages such as block chipping or uneven wear at the sharp corners of the block, while if it exceeds 90 degrees, the drainage performance will be hindered, and there will be problems between the vertical grooves. The object of the present invention can be achieved by forming a steep slope in the range of 30° to 60°; if this intersection angle is less than 30°, the corner of the block between both vertical grooves becomes too sharp, resulting in block chipping or unevenness. If the angle is greater than 60°, the drainage capacity will be reduced. The block 4, which is partitioned independently by both vertical grooves 1 and 2 and each horizontal groove 3, has a central circumference O-O,
The circumference line J-J is drawn between the side edges L-L of the tread part.
The ratio of the total surface area of block 4 occupying each area to the total area of each area divided into three equal parts by K-K is the minimum in the area close to the central circumference O-O of the tread part. The above area ratio is calculated based on the arrangement position of the central longitudinal groove 1 and the side longitudinal groove 2, their width, and the addition of the auxiliary tread minor grooves. , 40-60% area, 45-65% area, 65-90% area is desirable. (Embodiment) Now, FIGS. 1 and 2 show different embodiments of the present invention in the plane of development of the tread portion, and the equator of the tire, that is, the center circumference O-O of the tread portion, is sandwiched between the tread circumference and the tread circumference. A central longitudinal groove 1 that extends straight along the tread circumference, and a side longitudinal groove 2 that also extends straight along the tread circumference by dividing the distance from the side edge L-L of the tread portion of the central longitudinal groove 1 into two. , with blocks 4 which are arranged oppositely as tread main grooves and are partitioned independently from each other by combining with the tread main grooves a large number of lateral grooves 3 arranged obliquely in a herringbone pattern across these tread main grooves. This is the tread section. It should be noted that the tread sub-groove 5 on the central circumference of the tread part as shown in the example of FIG. A tread minor groove can also be added to at least one of the side edges of the tread in a suitable groove shape that is straight along the tread circumference.Furthermore, as shown in FIG. can also be abolished. In the illustrated example, the lateral grooves 3 are arranged symmetrically on the left and right sides of the plane including the center circumference O-O, but they may be arranged alternately so that they are approximately half pitch apart on the left and right sides of the tire. It may be hot. In any case, the horizontal groove 3 is formed between the center circumference O-O and the central longitudinal groove 1, and between the side longitudinal groove 2 and the tread portion side edge L-L with respect to the plane containing the center circumference O-O. between 60
It extends approximately in an S-shape or a mirror image S-shape along a fold line that is inclined at each intersection angle of a gentle slope within the range of ~90°, and a steep slope within the range of 30 to 60° between both longitudinal grooves 1 and 2. , it has a curved shape with an inflection point midway between the center circumference of the tread portion and the side edge of the tread portion. In this invention, the horizontal groove 3 is formed by each longitudinal groove 1 and 2.
The longitudinal grooves 1 and 2 may also have a uniform groove depth down to the skid base of the tread, or may have a slightly shallower groove depth than the longitudinal grooves 1 and 2. The tire pattern of this invention has a flattening ratio of
Applicable to passenger car tires in the range of 0.75 to 0.4,
This is particularly advantageous. As a specific example, apply the tire pattern with the following specifications according to Figure 1 to a tire of size 205/60R15,
Assemble this to a size 6JJ-15 rim and use standard internal pressure.
The following test was carried out by filling the container with 2.0Kg/cm ² .

[Table] The intersection angle of the reference broken line of the horizontal groove 3 with the plane containing the central circumference of the tread part is: A gentle slope of 79° between the central circumference O-O of the tread part and the central longitudinal groove 1. A steep slope of 46 degrees between the side longitudinal grooves 2 and a gentle slope of 74 degrees between the side edges L and L of the tread portion, along this reference broken line, approximately in the left half of Figure 1. The lateral grooves 3 are arranged in a curved shape with an S shape, and an inflection point between both vertical grooves 1 and 2, forming an almost mirror image S shape on the right side. The block area ratio was 50% area, 57% area, and 82% area. When we performed a wet skid test on a test tire with the above-mentioned flat tread pattern, we found that the speed at which aquaplaning occurs is 10km/h compared to the same type of comparative tire where the block area ratio is almost uniform throughout the area. /h was found to improve. Furthermore, when this test tire was mounted on an actual vehicle and tested over a distance of 50,000 km, there was almost no block chipping or uneven wear. (Effects of the Invention) As described above, according to the present invention, the wet skid resistance characteristics of a passenger car tire that has a wide contact width on the road surface can be advantageously improved without causing block chipping or uneven wear. be able to.

[Brief explanation of the drawing]

FIGS. 1 and 2 are developed views of the treads of each different embodiment. 1...Central longitudinal groove, 2...Side longitudinal groove, 3...Horizontal groove, 4...
Block.

Claims (1)

[Scope of Claims] 1. It has a tread portion that makes contact with the ground over a wide width, and this tread portion has a pair of central longitudinal grooves that extend parallel to each other across the central circumference of the tread portion, and A pair of lateral vertical grooves extending parallel to each other by dividing the distance from the side end of the tread portion into two are provided as tread main grooves, and furthermore, these tread main grooves are arranged diagonally intersecting in a herringbone pattern. A large number of lateral grooves are combined with the tread main groove to form a block-type pattern that is partitioned independently from each other, and each lateral structure has a central circumference and a central A gentle slope within the range of 60 to 90 degrees between the longitudinal groove and the side edge of the tread section, and a steep slope of 30 to 60 degrees between both vertical grooves. a curved shape extending in a substantially S-shape or a mirror image S-shape along a fold line inclined at the tread, and having an inflection point midway between the central circumference of the tread part and the side edge of the tread part; For the total area of each area divided into three equal parts between the circumference and the side edge of the tread part,
A passenger car tire with high wet skid resistance characterized by the above arrangement of blocks such that the ratio of the total surface area of the blocks occupying the region is minimized in a region near the central circumference of the tread portion. Tortled pattern.