JPH03178808A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To improve the dry and wet performances of an all-season pneumatic tire and resistance thereof against partial abrasion by providing a fine groove and an inclined notch in each block cellularized with a peripheral groove and a transverse groove in such a way that the fine groove is parallel to a transverse groove having one end open to an adjacent peripheral groove and the other end continuous to a center notch, and the inclined notch makes the continuous end connected to the adjacent groove. CONSTITUTION:Each block 52 of a block row cellularized with peripheral grooves 34 and 36, and a transverse groove 38, is provided with fine grooves 54 and 54 respectively open to the peripheral grooves 34 and 36, and parallel to the transverse groove 38. In addition, each inner end of the grooves 54 and 54 is connected via a center notch 56. Also, the fine groove 54 and the vicinity of the connection of the center notch 56 are made connected to the adjacent transverse grooves 38 and 38 via inclined notches 58 and 58. According to the aforesaid construction, the dry and wet performances of a pneumatic tire and partial abrasion resistance thereof can be improved.

Description

Detailed Description of the Invention (Field of Industrial Application) This invention can be used in all seasons, that is, it can be used not only on dry roads but also on slippery roads covered with rain, snow, and ice. This invention relates to a pneumatic tire that can be used for.

(Prior art) The required performance of tires varies greatly depending on the road surface conditions on which they are to be driven.There are so-called "summer tires" that exhibit excellent performance on dry and wet roads, and tires that exhibit excellent performance on icy and snowy roads. They can be broadly categorized into ``winter tires,'' which provide excellent performance, and ``all-season tires,'' which are intended for use throughout the four seasons.

Summer tires usually have 3 to 5 tires extending in the circumferential direction of the tire, with emphasis placed on drainage performance on the contact surface of the tread.
The approximately linear circumferential grooves of the book are arranged at approximately equal intervals in the width direction, while the lateral grooves that intersect these circumferential grooves are arranged at approximately equal intervals in the tire circumferential direction, and these circumferential grooves and lateral grooves are arranged at approximately equal intervals in the tire circumferential direction. It is equipped with block rows divided by directional grooves, and in order to achieve both steering stability on dry road surfaces (dry performance) and steering stability on wet roads (wet performance), these circumferential grooves and lateral grooves Various arrangements have been made for the arrangement.

On the other hand, for winter tires, zigzag-curved, wide grooves and large groove depths are preferably used as the circumferential grooves and lateral grooves, and these grooves and the blocks divided by the grooves are used to protect the road surface. Attention has been paid to increasing the driving and braking performance of tires by increasing their grip.

For example, as shown in FIG. 4, the all-season tire 10 has a plurality of circumferential grooves 14 extending in a zigzag shape in the tire circumferential direction in the center of the tread portion 12.
Wide lateral grooves 16, also in a zigzag shape, are arranged at predetermined intervals in the tire width direction and extend between mutually adjacent circumferential grooves, and mutually adjacent wide lateral grooves 16 Three rows of blocks 20 each having narrow lateral grooves 18 arranged between the grooves at approximately equal intervals in the circumferential direction of the tire.
and forming cuts 22a and 22b extending substantially parallel to the lateral grooves between adjacent circumferential grooves to divide each block into three block elements in the tire circumferential direction,
By setting the rigidity of each block low,
Efforts are being made to improve ground contact.

(Problem to be Solved by the Invention) Tires with such a tread pattern have difficulty driving on icy and snowy roads due to the improvement in the frictional force of the tire due to the edges of the cuts that divide each block into multiple elements. However, when a force is applied in a direction perpendicular to these notches, such as during driving and braking, each notch is When the block elements move easily and the vehicle runs on a dry road surface, the wear of the tread rubber on the kick-out side of each block element is significantly accelerated compared to that on the push-in side.

For this reason, uneven wear in the form of a sawtooth in the circumferential direction occurs in the middle of the tire's life, resulting in problems such as deterioration of tire performance and deterioration of the appearance. This problem exists regardless of the internal structure of the tire, whether it is a bias tire or a radial tire.

The present invention was made in view of such problems,
The purpose is to provide a pneumatic tire that has excellent dry and wet performance and excellent uneven wear resistance and can be used throughout the seasons.

(Means for Solving the Problems) In order to achieve this object, the present invention provides a plurality of circumferential grooves formed in the tread portion and extending in the tire circumferential direction and spaced apart from each other in the tire width direction. , a plurality of lateral grooves extending over the circumferential direction iM and spaced apart from each other in the tire circumferential direction, and at least a block row partitioned by the circumferential grooves and the lateral grooves. In the tire, each block in each row of blocks has a pair of narrow grooves each opening at one end in an adjacent circumferential groove and extending inwardly substantially parallel to the lateral groove; a central notch connected to each other end, and a pair of inclined notches forming an acute angle with respect to the central notch and extending from the vicinity of each joint of the thin groove and the central notch to an adjacent lateral groove. Become.

Now, FIG. 1 shows a tread pattern of a pneumatic tire 30 to which the present invention is applied. Tread portion 32 of tire 30
Although it varies depending on the tire size, usually 2 to 5
The circumferential grooves 34, 34 and 36, 36 extending substantially in the circumferential direction of the tire, in this embodiment four circumferential grooves 34, 34 and 36, 36, are arranged spaced apart from each other in the width direction of the tire.

The groove width of the pair of circumferential grooves 34 adjacent to each other in the center of the tread is equal to the groove width of the other circumferential grooves 36 disposed apart from each other in the width direction of the grooves and forming a pair with each other. The groove depth is set to be larger than the groove width, while the groove depth is set deep. From this,
Sufficient drainage performance in the tire circumferential direction can be ensured.

and adjacent circumferential grooves 34.34 and 34 and 3.
6 are communicated with each other through lateral grooves 38 which are diagonally intersecting in one direction within an angle range of 15° to 35'' with respect to the tire equatorial plane and are spaced a certain distance apart in the circumferential direction. The block rows 40, 42 and 42 are partitioned.

- The groove width of these lateral grooves 38 is narrower than that of the circumferential groove 34, but at the narrowest part, the width of the circumferential groove 38 is narrower than that of the circumferential groove 34.
The groove width shall be 50% or more of the groove width. This is because this is the minimum width of the groove to achieve the effect of shearing the snow column within the ground contact surface, which provides important traction when driving on snowy roads.

On the other hand, the groove depth of the lateral groove 38 is at least partially shallower than that of the circumferential groove 34, and is within the range of 0 to 50% of the value measured from the bottom of the circumferential groove 34. The block defined by the circumferential grooves and the lateral grooves has relatively high rigidity.

In addition, in this example, the shoulder portion 44 of the tire 30 also has a
A circumferential groove 46 extending in the tire circumferential direction is provided, and a plurality of lateral grooves 48 diagonally intersecting the circumferential groove 36 of the tread portion 32 and spaced apart from each other in the tire circumferential direction extend to a part of the shoulder. A shoulder block row 50 is formed.

The angle that the portions of these lateral grooves 48 that open into the circumferential grooves 36 of the tread portion 32 make with the tire equatorial plane is the angle that the lateral grooves 38 provided in the tread portion make with the tire equatorial plane. have approximately equal parts. Further, the lateral groove 48 is bent at its intermediate portion in a direction opposite to the equatorial plane and opens into a circumferential groove 46 provided in the shoulder portion 44 .

In this embodiment, the groove width from the opening to the circumferential groove 36 to the bent portion of the lateral groove 48 provided at the end of the trend portion 32 is equal to the lateral direction of the tread portion. The groove width from the bent portion to the portion opening into the circumferential groove 46 is approximately equal to that of the groove 38, and the groove width is approximately equal to that of the circumferential groove 34 of the tread portion 32, and the groove depth is approximately equal to that of the lateral groove 46. Similar to 38, the circumferential groove is equivalent to or shallower than the circumferential groove,
Furthermore, a part of it may be made shallower. and,
The lateral grooves 48 are formed by being shifted by half a pinch in the tire circumferential direction at intervals approximately equal to the groove intervals of the lateral grooves 38 in the tread portion. This results in a reduction in pattern noise.

Of course, the extending direction and width of the lateral groove 48 in a portion of the shoulder may be changed as necessary.

Each block element of the shoulder block row 50 is divided by a notch extending substantially parallel to the lateral groove 48 that partitions each block element, and the portion where the notch opens into the circumferential groove 36 at the tread end is enlarged. This increases the shape of the notch and increases its edge effect.

By the way, the block row 4 formed in the center of the tread portion
Each block 52 constituting blocks 0 and 42 is, for example, a first
As shown in Figure (b), the circumferential grooves 34 and 36 that are spaced apart from each other in the tire width direction are provided with a pair of narrow grooves 54 each having one end open.

These narrow grooves 54 are disposed substantially parallel to the lateral grooves 38, 38 spaced apart from each other in the circumferential direction of the tire at positions that substantially divide the interval into thirds in the circumferential direction. t
The respective ends of slots 38 extending inwardly from f434 and 36 distances 11 and 1°, respectively, are interconnected by a central notch 56.

The groove width of the narrow if 454 is 1.5 mm to 3 mm, preferably 2 inches, and the groove depth is approximately the same as the horizontal groove 38. By setting the groove width and groove depth within these ranges, the narrow grooves will not close unless excessive external force is applied to the tread, and a sufficient edge effect can be expected from the narrow grooves. be able to.

- The width of the central cut 56 connecting the narrow grooves forming the force pair is 0.
．． The cutting depth shall be selected within the range of 5 mm to 1 mm, and by setting the cut depth to be the same as or slightly shallower than the groove depth of the narrow groove 54, and ensuring that the cut is always closed within the contact surface, the rigidity of the block can be improved. can minimize the decrease in

Here, the length k of the central cut 56 is equal to the length k of the pair of narrow grooves 54.
It is assumed that the value is set to be approximately equal to or slightly longer than the value obtained by dividing the sum of Therefore, the length of the narrow groove is 1. and 12 are set equal, 1+=lz=.

The grooves extend from the vicinity of the joint between the pair of narrow grooves 54 and the central cut 56, in this embodiment, from the joint to the respective lateral grooves 38 spaced apart in the tire circumferential direction that partition each block 52. A pair of inclined cuts 58 are provided. This forms an S-shape or two-shape together with the notch 56.

The angle of this inclined cut 58 with respect to the central cut 56 is 9
0', i.e. arranged at an acute angle to the central notch 56, each block 52 is divided into four block elements 52a, 52b, 52c and 52.
Divide into d. Note that the groove width and groove depth of the inclined cut 58 are set to values equivalent to the groove width and groove depth of the central cut 56.

In the embodiment shown in FIG. 1(b), block elements 52a and 52b adjacent in the tire width direction and defined by a narrow groove 54 and a central notch 56, and elements 52c and 5
By setting the block element length in the tire circumferential direction of each of the elements 2d, that is, the block elements 52b and 52c, to be longer than that of the other block elements 52a and 52c, the circumferential groove of the lateral groove 3 days 36 is enlarged, and the groove width of the middle part of the lateral groove 38 is set small, and furthermore, the block elements 52a and 52b that form a pair adjacent to each other in the tire width direction and the pair of block elements It is also possible to make the circumferential grooves 34 and 36 extend in the circumferential direction of the tire so as to move in and out from left to right in a crank shape by mutually shifting the grooves 52c and 52d in the tire 1 depression direction. Of course, the circumferential grooves 34 and 36 can be made to extend substantially straight in the tire equatorial plane by arranging these block elements without shifting them in the tire width direction. By changing, various changes are possible.

Incidentally, the internal structure of the tire 30 to which the present invention is applied is as follows:
As shown in Fig. 2, more than 1 ply of organic fiber cords such as nylon, polyester, rayon, etc. are arranged at approximately 90 degrees with respect to the tire equatorial plane S.
A carcass 62 consisting of layers of at most 3 plies is toroidally connected between a pair of beet rings 60,
On the outer periphery of the carcass 62, a plurality of non-stretchable cords represented by steel cords or aromatic polyamide fibers are arranged in one direction at a shallow angle to the tire equatorial plane S, for example, in an angle range of 10° to 30°. In some cases, an auxiliary layer is formed by spirally winding a nylon cord approximately parallel to the equatorial plane S around the outer periphery of the belt main body, which is overlaid so that the plies cross each other diagonally. A tread portion 32 made of rubber that is in contact with the road surface is provided on the outer periphery of the belt 64.
It has a so-called radial structure.

On the other hand, in another embodiment of the invention shown in FIG.
are curved and extended to make the lengths of each block element in the tire circumferential direction in the tread 32 substantially equal, and are partitioned in the tire circumferential direction by a narrow groove 54 and a central notch 56 to form a pair. By arranging the block elements without relatively shifting them in the tire width direction, almost straight circumferential grooves 34 and 36 are formed, and the lateral grooves 48 that partition the shoulder block rows 50 1 except that a notch is provided that opens almost perpendicular to the
It has the same configuration as the embodiment shown in Figure (a).

(Function) In such a tire, each block of the block row arranged in the trend portion 32 has one end opened in the circumferential groove adjacent to the width direction of the tire, and substantially extends in the lateral direction. A wide narrow groove extending parallel to the groove 38, a narrow central notch connecting the narrow grooves, and a narrow inclined notch making an acute angle to the central notch and extending to the lateral groove 38, thereby forming four grooves. Since the narrow grooves are divided into block elements, unless an excessive external force is applied to the tread during running, the narrow grooves will not close within the ground contact surface, increasing the edge effect of the blocks. Since the notch communicates with a thin groove having a groove width smaller than that of the circumferential groove, the block element is more susceptible to external forces acting in the tire circumferential direction than when the cut opens directly into the circumferential groove. There is no reduction in rigidity, and therefore, the movement of the block element at the end of the narrow groove can be reduced, and wear resistance, braking performance in wet conditions, etc. do not deteriorate. Moreover, even when driving on a road surface with a relatively small coefficient of friction, the notches connected to the narrow grooves can be expected to have a synergistic effect with the edge effect of the narrow grooves.

In addition, the central notch and the inclined notch are dimensioned so that they can close together upon contact with the ground, and the decrease in rigidity of the block element is minimized, so a synergistic effect with the edge effect of the narrow grooves can be expected.

In this way, the narrow grooves, central notches, and slanted notches that divide the block elements are arranged organically, so even when external forces are applied in the tire circumferential direction, such as during driving and braking, each block is Movement is effectively suppressed, so uneven wear does not occur, and the edge effect of the narrow grooves and cuts allows sufficient running even on road surfaces with a small coefficient of friction.

(Example) Invention tires A and B having tread patterns shown in FIGS. 1(a) and 3 and conventional tire C having tread pattern shown in FIG. 4 were used to improve dry performance, wet performance, and snow performance. Comparative running tests were conducted on the ring and its abrasion resistance.

◎Test tires: Both the invention tire and the conventional tire had a size of 1500 d and were arranged at an angle of approximately 90° with respect to the tire equator.
A carcass with two layers of plies of /2 polyester cord, and a ply of steel cords arranged in one direction at an angle of 20' with respect to the tire equator.
Size 195/70 R14, tread width 140, with belts arranged in two layers so that each cord crosses each other
This is a passenger car tire with a negative ratio of approximately 35%, and its specifications are shown in the table below.

Table ◎ Test method: Each tire was mounted on an actual vehicle, and each test was conducted under internal pressure and load conditions based on JIS standards.

・Dry performance: Various types of driving were conducted on a circuit course with a dry road surface, and an overall feeling evaluation of straight-line performance and turning performance was performed and an index evaluation was performed.

- Wet performance: Comprehensive feeling evaluation such as turning performance and braking performance on a wet road surface at a water depth of 0-1 ffIm was performed and an index evaluation was performed.

・Feeling on snow: An index evaluation was conducted by comprehensively evaluating the feeling of starting, climbing, turning, straight-line performance, etc. on smooth, compacted snow roads.

- Uneven wear characteristics: The presence or absence of uneven wear was visually inspected and indexed when running on a general road for 11,000 km.

The results of the above test are shown in Table 2. The larger the index, the better the performance.

As is clear from Table 2 above, it was confirmed that the tire according to the present invention has improved performance in all respects compared to the conventional tire.

(Effects of the Invention) Thus, according to the present invention, dry performance and uneven wear resistance can be improved without impairing wet performance and on-snow feel, and the life of the tire can be significantly extended.

[Brief explanation of drawings]

FIG. 1(a) is a diagram showing the tread pattern of the tire of the present invention, FIG. 1(a) is an explanatory diagram showing an enlarged block of the tire shown in FIG. 1(a), and FIG. FIG. 1 is a cross-sectional diagram showing the internal structure of the tire, FIG. 3 is a diagram showing a tread pattern of another embodiment of the present invention, and FIG. 4 is a diagram showing a tread pattern of a conventional tire. FIG. 10.30-m-Tire 12.32 - Tread portion 14, 16.34, 36.46-- Circumferential groove 16.18, 38.48- Lateral groove

Claims (1)

[Scope of Claims] 1. A plurality of circumferential grooves formed in the tread portion and extending in the tire circumferential direction while being spaced apart from each other in the tire width direction; In a pneumatic tire comprising a plurality of lateral grooves spaced apart from each other in the circumferential direction and at least rows of blocks partitioned by the circumferential grooves and the lateral grooves, each block in each row of blocks is adjacent to each other. a pair of narrow grooves each having one end open in the circumferential groove and extending substantially parallel to and inward of the transverse groove; a central notch continuous to each other end of the narrow groove; 1. A pneumatic tire comprising: a pair of inclined notches forming an acute angle and extending from near each joint of the narrow groove and the central notch to an adjacent lateral groove.