JP3115585B2 - Pneumatic radial tire - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pneumatic radial tire having excellent turning performance, and in particular, to effectively prevent occurrence of abnormal wear in a tread side area.

(Prior Art) In a conventional pneumatic radial tire having a plurality of circumferential grooves extending in a zigzag or straight line in the circumferential direction of the tire, each circumferential groove is traversed in FIG. 3 (a). As shown in the figure, a normal line 32 standing on the tread surface 31 and a circumferential groove 33
The two groove walls 34 are separated from each other toward the tread surface side so that the angle α formed by each of the opposed groove walls 34 is equal to each other, and the two groove walls 34 are curved surfaces having a specific radius of curvature. It is common to form a smooth continuous connection with the bottom wall made of.

(Problems to be Solved by the Invention) However, in a conventional tire having a circumferential groove having such a cross-sectional shape, for example, when a large lateral acceleration acts on the tire due to high-speed turning on a circuit or the like, particularly, In the tire outside the turn, the circumferential groove 33 extending to the outer portion of the tire is greatly crushed by the road surface reaction force, and the deformation of the tread surface at this time is as follows.
As shown in the sectional view of FIG. 3 (b) from which the road surface is removed, a portion where the amount of protrusion of the tire outward in the radial direction increases due to the deformation, in other words, a particularly strong ground contact is made. The shoulder portion A adjacent to the outside of the tread tread portion and the land end portion B adjacent to the inside of the outermost circumferential groove 33 in the tire width direction bear a particularly large road surface reaction force. On the other hand, the land end portion C adjacent to the outside of the circumferential groove 33 rises from the road surface, and as a result, not only the turning performance is reduced, but also both of the portions A,
Abnormal wear occurs relatively early, in which the land end portion C, on which the contact pressure hardly acts, remains as it is without wear, while B wears remarkably, which leads to a reduction in tire life, generation of vibration, and motion. This will result in a decrease in characteristics and the like.

Therefore, in order to solve such a problem, the width of the circumferential groove is reduced to such an extent that the two groove walls are in contact with each other, and the deformation of the tire land portion is restrained under the contact of the two groove walls, so that the wear pattern is reduced. Attempts were also made to improve the tire, but according to this, the groove volume of the tire is reduced,
A decrease in drainage on wet road surfaces was inevitable.

The present invention advantageously solves such a problem of the related art, and ensures excellent turning performance without lowering drainage performance, and sufficiently prevents occurrence of abnormal wear due to turning driving. It is intended to provide a pneumatic radial tire that can be used.

(Means for Solving the Problems) The present invention provides two or more circumferential grooves extending in a zigzag or straight line in a tire circumferential direction on a tread tread portion, and each circumferential groove and tread end are provided. A pneumatic radial tire having a row of blocks formed between
At least in the circumferential groove located closest to the tread end in the tread side area located on the outside of the vehicle in the tire mounted state, at least in the tire width direction cross section, on both groove walls, From the radially outer position of the tire from the bottom of the groove, the respective opening sloped portions that are inclined in the direction in which the groove width gradually expands toward the tread surface are provided, and the groove wall on the tread end side is bent. The angle of inclination of the expanded slope portion with respect to the tire normal is made constant over the entire circumference of the tire, and the tire normal of the expanded slope portion provided on the groove wall near the tread center. Is larger than the inclination angle with respect to.

This will be described more specifically with reference to a tire having a tread pattern illustrated in FIG.

This figure shows a front view of a tire mounted on a vehicle. The left side of the figure is located outside the vehicle, and the right side is located inside the vehicle.

Here, a single circumferential narrow groove 2 extending linearly in the tire circumferential direction is provided at a central portion of the tread tread portion 1, and is located at a predetermined distance from the circumferential narrow groove 2 toward the tread end. In addition, two linear and circumferential thick grooves 3 which are symmetrical with respect to the circumferential direction are provided, and the circumferential thick grooves 3 are further separated from the circumferential thick grooves 3 by a predetermined distance toward the tread end side. Two linear circumferential intermediate grooves 4 which are linearly symmetric with respect to the narrow grooves 2 are provided, and a plurality of substantially "H" -shaped grooves are formed between each circumferential thick groove 3 and the tread end. Are formed at predetermined intervals in the circumferential direction of the tire, extend from the circumferentially thick grooves 3 to the circumferentially narrow grooves 2, and are obliquely viewed from the front of the tire in the mounting posture. Facing down,
At the point where the inclined groove 6 ending without reaching the circumferential narrow groove 2 is formed, at least
FIG. 2 is an enlarged cross-sectional view of a main portion in the tire width direction of the tread edge on the outer side of the vehicle, and in FIG. 2, the respective groove walls of the circumferential intermediate groove 4 located closest to the tread ends on the inner and outer sides. From the radially outward position of the tire from the groove bottom 7 thereof, respective expanding inclined portions 8 and 9 are formed which incline in the direction in which the groove width gradually expands toward the tread surface, and these inclined portions are formed. Of the widened inclined portion 8, which is provided on the groove wall 10 on the tread end side and widens through the bent portion,
The inclination angle α with respect to the tire normal placed on the tread surface,
The inclination is made constant over the entire circumference of the tire, and the angle of inclination of the widened inclined portion 9 provided on the groove wall 11 near the center of the tread is set to be larger than the inclination angle β with respect to the same normal line of the tire. And

(Operation) When such a pneumatic radial tire is mounted, for example, on the right front wheel of a vehicle and turns leftward, the arrow shown in FIG. 2 is attached to the outer end of the tire outside the turn. Thus, a road surface reaction force acts in a direction from the outer tread end to the inner tread end.

In this case, as shown by a broken line in FIG. 2, the groove wall 10 located on the tread end side of the circumferential intermediate groove 4 has the expanded inclined portion 8 provided there moved substantially in parallel to the tread central portion side. As a result, the tread surface does not have an extreme protruding portion radially outward of the tire, so that the shoulder land portion, here each shoulder block 12, Are almost uniformly grounded, and the ground pressure is sufficiently uniform throughout the block 12.

Therefore, with this tire, it is possible to effectively prevent the occurrence of abnormal wear on the shoulder block 12 due to the generation of a portion having a significantly high contact pressure during turning of the vehicle, of,
Based on the contact under a sufficient contact pressure, the cornering force can be increased to improve the turning performance.

The widened inclined portion 8 of the groove wall 10 always secures a large groove volume in cooperation with the widened inclined portion 9 of the other groove wall 11 even when the groove wall 10 is deformed as described above. As a result, excellent wet drainage performance can be brought about not only when the above-mentioned road surface reaction force does not act but also when it acts.

By the way, when the amount of deformation of the circumferential intermediate groove 4 and thus the shoulder block 12 becomes particularly large, the radially inner end of the expanding inclined portion 8 is formed under the action of the bent portion of the groove wall 10. The contact with the shoulder block 11 further increases the block rigidity of the shoulder block 12, so that the cornering force can be further increased. In this case as well, each of the expanding inclined portions 8, 9 can of course effectively contribute to securing the groove volume under the action of the bent portion.

Also, here, the expanded inclined portion 9 provided on the groove wall 11 causes the second block 13 adjacent to the intermediate groove 4 on the tread central portion side to act on the second block 13 there due to the above-described road surface reaction force. 3 (b), the ground pressure of the second block 13 is also made substantially uniform over the entirety of the block 13 so as to prevent the occurrence of the overhang deformation as shown by the portion B in FIG. It is possible to effectively prevent the occurrence of abnormal wear on the tire, and at the same time, it is possible to ensure an increase in cornering force.

Further, in this tire, by making the inclination angle α of the expanded inclined portion 8 with respect to the tire normal larger than the inclined angle β of the enlarged inclined portion 9 with respect to the tire normal, the groove edge of the shoulder block 12 is particularly improved. The portion and the portion in the vicinity thereof are more effectively prevented from rising from the road surface.

Here, when the inclination angle α is equal to or smaller than the inclination angle β, the groove edge portion of the second block 13 and the vicinity thereof generate a large road surface reaction force in relation to the rigidity balance of the two blocks 12, 13. Since the contact pressure is directly received, the contact pressure of that portion becomes larger than that of the other portions of the block 13, so that the contact pressure of the groove edge portion of the shoulder block 12 and the vicinity thereof becomes too low, and therefore, The effect of providing the widening inclined portion 8, in other words, the uniformity of the ground pressure of the shoulder block 12 is impaired, and the significance of providing the inclined portions 8 and 9 is greatly reduced. become.

 Here, the inclination angle α can be set to 20 ° ≦ α ≦ 60 °, and more preferably, 30 ° ≦ α ≦ 50 °.

 The inclination angle can be set to 10 ° ≦ β ≦ 45 °, and more preferably, set to 15 ° ≦ β ≦ 35 °.

In other words, when α <20 °, it is not possible to secure sufficient block rigidity to prevent the groove edge portion of the shoulder block 12 and the vicinity thereof from rising off the road surface,
If α> 60 °, the surface area of the block 12 becomes too small,
The required road grip force cannot be secured.

When β <10 °, there is almost no change from the angle of the conventional tire, and the desired effect cannot be obtained.
At 45 °, the external resistance of the groove edge portion of the second block 13 and the vicinity thereof, in other words, the ground pressure becomes too large.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a tread pattern showing an embodiment of the present invention.

Since the internal reinforcement structure of the tire is the same as that of a general radial tire, illustration is omitted here.

In this example, the width of one circumferential narrow groove 2 formed on the tread tread portion 1 and extending linearly in the tire circumferential direction is 4.5 m.
m, the groove width of the circumferential large groove 3 extending on each side wall of the narrow groove 2 is 9.5 mm, and the groove of the circumferential intermediate groove 4 extending at a position closer to the tread end than each of these thick grooves 3 With a width of 7.0 mm,
The formation position of each of the intermediate grooves 4 from the adjacent tread edge is set in the range of 15% to 25% of the tread tread width, and from the circumferentially large groove 3 to the tread edge, substantially “he” in front view of the mounted tire. The groove width of the widthwise groove 5 extending in a character shape is 7.0 mm
And the groove wall on the tread end side of the circumferential intermediate groove 4
10 and a groove wall 11 near the center of the tread, respectively, from the groove bottom 7 in a radially outward position of the tire, to a respective expanding inclined portion 8 which inclines in a direction in which the groove width gradually expands toward the tread surface. , 9 and the groove wall 10 on the tread end side is expanded through a bent portion, and the tire set on the tread surface of the expanded inclined portion 8 provided on the groove wall 10 on the tread end side The inclination angle α with respect to the normal is made constant over the entire circumference of the tire, and is preferably larger than the inclination angle β with respect to the same tire normal of the expanding inclined portion 9 provided on the groove wall 11 near the center of the tread. Makes the difference between the two inclination angles in the range of 10 to 30 °.

In this case, the radially inner ends of the tires of the two widened inclined portions 8, 9 are located at 10 to 70% of the groove depth, particularly 20 to It is preferable to be located within the range of 50%, and if it is less than 10%,
Because it is too close to the prior art, the expected effect cannot be brought about, and its position exceeds 70%. In this case, too, the function and effect unique to the widening inclined portions 8, 9 cannot be sufficiently exhibited.

Also here, preferably, by setting the groove width of the circumferential intermediate groove 4 in the range of 5 to 18 mm, improvement in wet drainage and increase in cornering force, and eventually,
It effectively balances prevention of abnormal wear. That is, if it is less than 5 mm, it is practically impossible to form the required widened inclined portions 8 and 9 in relation to the groove depth, and if it exceeds 18 mm, the widened inclined portions 8 will deform the block. The groove width becomes too wide,
In other words, the block width becomes too small, and it is difficult to prevent the uneven wear by suppressing the movement of each block as a unit, and the groove is deformed as in the conventional example.

In the tire having the tread pattern as described above, the size is 225 / 50V16, the tread tread width is 186 mm, and each circumferential intermediate groove 4 is formed at a position 17% of the tread tread width from the tread end, The groove depth of the intermediate groove 4 is 8.0mm,
The inclination angle α of the widened inclined portion 8 with respect to the tire normal is 45 °,
The tire with the angle of inclination β of 20 ° with respect to the tire normal to the widened sloped part 9 was mounted on an actual vehicle, and the tire surface was visually observed after running the circuit for 20 km by a test driver. It was confirmed that the abrasion resistance was almost the same as that of a new article, in other words, the occurrence of abnormal wear could be effectively prevented.

In terms of athletic performance, the change in grip force over time under the action of high lateral acceleration during circuit running is extremely small, and it has been confirmed that it has at least three times the durability of circuit running compared to conventional products. Was done.

In addition, the exercise performance at the time of new, especially the grip limit, limit control performance and high-speed straight running stability,
Significantly improved compared to conventional tires.

(Effects of the Invention) Thus, according to the present invention, in particular, the action of each of the widened inclined portions sufficiently prevents a decrease in wet drainage performance and exhibits excellent turning performance under a high cornering force. Obviously, against the action of large lateral acceleration, it can effectively prevent at least the occurrence of abnormal wear on the shoulder block and the second block, and at the same time, can always exert excellent exercise performance and increase durability Can be improved.

[Brief description of the drawings]

FIG. 1 is a tread pattern showing an embodiment of the present invention, FIG. 2 is an enlarged sectional view of a main part showing a circumferential intermediate groove, and FIG. 3 is a partial transverse sectional view showing a circumferential groove of a conventional tire. is there. DESCRIPTION OF SYMBOLS 1 ... Tread tread part, 2 ... circumferential narrow groove 3 ... circumferential thick groove 4, circumferential intermediate groove 5 ... width groove, 7 ... groove bottom 8, 9 ... widening inclined part , 10, 11… Groove wall 12… Shoulder block, 13… Second block α, β… Inclination angle

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60C 11/01-11/13

Claims (1)

(57) [Claims] 1. A pneumatic radial tire in which two or more circumferential grooves extending in the tire circumferential direction are provided on a tread tread portion and a block row is formed between each circumferential groove and a tread end. In the tire mounted on the vehicle, at least in the circumferential groove located closest to the tread edge in the tread side area located on the outside of the vehicle, both groove walls in the tire width direction cross section In addition, from the radially outer position of the tire than the groove bottom thereof, while providing each expanding inclined portion inclined in a direction in which the groove width gradually expands toward the tread surface, the groove wall on the tread end side, Expanded through the bent portion, the angle of inclination of the expanded slope portion with respect to the tire normal, while maintaining a constant over the entire circumference of the tire, of the expanded slope portion provided on the groove wall near the tread center, Tire normal A pneumatic radial tire having a larger angle of inclination with respect to.