JPH04151307A - Pneumatic radial tire - Google Patents

Abstract

PURPOSE:To bring a second block into contact with the ground over its whole with sufficiently equal ground contacting pressure and prevent the abnormal wear of the block at the time of vehicle high speed turning travel, by specifying at least the contour shape of the block in its tread width direction section. CONSTITUTION:At a tread portion 1, one peripheral narrow groove 2, two peripheral thick grooves 3, two linear peripheral middle grooves 4, plural width direction grooves 5 and plural inclination grooves 6, are provided, and with these, second block rows 7 and shoulder block rows 8 are formed. In this instance, at least a tread sphere located on the side of the vehicle outer side in a tire that is in a posture to be attached, as for a contour shape within a tread width direction section at each block 7a of the second block rows 7, its tread center portion side end edge 7b is positioned on the maximum diameter contour line (a) of the whole of the tread portion. And a portion that is positioned on the tread end side further than the end edge 7b, is gradually separated from the extension portion of the maximum diameter contour line (a) as it recedes from the end edge 7b.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a high-performance pneumatic radial tire for passenger cars, and in particular, to effective prevention of abnormal wear on the tire during high-speed cornering of the vehicle. This prevents cornering from occurring and also ensures the generation of high cornering force.

(Prior Art) The tread surface of a conventional pneumatic radial tire has a contour line shape consisting of a single arcuate curve, or a contour line shape consisting of a single arcuate curve in the cross section in the tread width direction, as shown in FIG.
As shown in Figure (b), it was common to have a contour line shape that was a combination of two types of arcuate curves.

(Problem H to be Solved by the Invention) By the way, a tire having the above-mentioned contour shape at the end of molding, after being filled with internal pressure, has a fifth layer due to the influence of the belt as an embedded reinforcing layer and other factors. As shown in an exaggerated manner in Figure (a), in the cross section in the tread width direction, the end portions of each land portion protrude toward the outer circumference compared to other portions, and this causes the tire to When a large road reaction force, which occurs when a vehicle makes a high-speed turn and is directed from the outside to the inside of the turn, acts on the block as shown by the arrow SF in the figure, the protruding end of each land section is affected by the tread surface. There were problems such as lifting of the road surface and getting caught between the road surface and the land area.

In other words, due to such road surface reaction force, the protruding portion A on the tread center side of each land portion rises from the road surface, as shown in Fig. 5(b), whereas the protruding portion A on the tread edge side Since the protruding part B is forced to directly support the road reaction force under the action of large ground pressure, abnormal wear occurs particularly in the protruding part B and its neighboring parts, resulting in severe wear and tear. , the protruding portion B is caught between the road surface and the land area, and this also causes abnormal wear in a form different from that described above.Therefore, not only large cornering force is generated, but also high It was not possible to ensure the generation of gripping force, and moreover, the steering stability was significantly impaired.

The present invention advantageously solves the problem of the prior art, and provides a solution to the problem of the prior art, and provides a
By effectively preventing lift-off from the road surface, entrainment, etc., and ensuring that each land part is grounded over its entirety, preferably with approximately uniform ground pressure, abnormal wear on the land parts is sufficiently prevented. The present invention provides a pneumatic radial tire that generates high cornering force and grip force, and also greatly improves handling stability.

(Means for Solving the Problems) The present invention provides three or more circumferential grooves formed on a tread surface and extending in the tire circumferential direction, and grooves between these circumferential grooves and between the circumferential grooves and the tread end. A pneumatic radial tire comprising a plurality of land section rows partitioned in between, the tire being mounted on a vehicle, at least in a tread region located on the outside of the vehicle, which also includes at least a tread region. The second land part adjacent to the tread center side of the shoulder land part located closest to the end, whose edge on the tread center side in the cross section in the tread width direction is the maximum diameter of the entire tread tread surface. The part located on the contour line and located closer to the tread edge than the edge,
As the distance from the edge increases, the distance from the extended portion of the maximum diameter contour line increases.

Preferably, the maximum separation distance of the second land portion from the extended portion of the maximum diameter contour is 15% or less of the groove depth of the circumferential groove adjacent to the land portion, while at least 0.
The length shall be 2111m or more.

Preferably, at least the contour line of the second land portion is formed in a curved shape, for example, an arc, in the cross section in the tread width direction.

More preferably, similarly to the second land part, the edge of the third land part on the tread center side in the cross section in the tread width direction is located on the maximum diameter contour of the entire tread surface part. At the same time, the portion located closer to the tread end than the end edge, as the distance from the end edge increases,
It is gradually spaced apart from the extension of the maximum diameter contour.

More preferably, in the circumferential groove adjacent to the tread center side of at least the second land portion, the groove wall located on the tread end side thereof is directed toward the tread surface from a position closer to the tread surface than the groove bottom. The groove width is inclined in the direction in which the groove width gradually increases.

These matters will be explained more specifically using a tire having a tread pattern illustrated in FIG. 1.

Note that this figure shows a front view of the tire as it is mounted on a vehicle.

Here, a single circumferential narrow groove 2 is provided in the center portion of the tread surface portion 1 and extends linearly in the circumferential direction of the tire, and a circumferential groove 2 is provided at a predetermined distance from the circumferential narrow groove 2 toward the tread end. Two circumferential large grooves 3 are provided which are line symmetrical to the circumferential narrow groove 2, and a circumferential narrow groove 3 is provided at a predetermined distance from each of these circumferential large grooves 3 toward the tread end. Two linear intermediate circumferential grooves 4 are provided which are line symmetrical to the groove 2, and a plurality of circumferential intermediate grooves 4 are provided between each circumferential thick groove 3 and the tread edge. widthwise grooves 5 are formed at predetermined intervals in the circumferential direction of the tire, further extending from each of the circumferential large grooves 3 in the direction of the circumferential narrow grooves 2,
By forming the inclined grooves 6 that face diagonally downward when viewed from the front of the tire in the mounting position and end without reaching the circumferential narrow grooves 2, the grooves between the circumferential thick grooves 3 and the circumferential intermediate grooves 4, and In the place where the second block row 7 and the shoulder block row 8 are formed between the intermediate groove 4 and the tread end, the second block row The contour shape of each block 7a in the cross section in the tread width direction is such that the edge 7b on the tread center side is located on the maximum diameter contour line a of the entire tread tread surface, and The portion located closer to the tread end than the edge 7b has a shape that gradually separates from the extended portion of the maximum diameter contour line a as the distance from the edge 7b increases, and preferably, the contour shape is arcuate, and the block The maximum distance in the tread thickness direction from the extended portion of the maximum diameter contour line a of the limbus line is not more than 15% of the depth of the circumferential intermediate groove 4 adjacent to the block 7a, but not less than 0.2 mm. shall be.

Here, the outline shape of not only the block 7a of the second block row 7 but also the land portion adjacent to the tread center side of the second block row 7, here the rib 9, in the cross section in the tread width direction is referred to as the block 7a. It can also be based almost the same as that of .

Furthermore, in the illustrated example, in the respective circumferential grooves 3 and 4 adjacent to the tread center side of the second block 7a and the shoulder block 8a, the groove walls 3a and 4a located on the tread end side of each of the second block 7a and the shoulder block 8a are groove bottom 3b,
4b from a position closer to the tread surface in a direction in which the groove width gradually expands toward the tread surface, and preferably the angle of intersection of the inclined portion with the normal to the tread surface is 20 to 50 degrees. The range shall be .

(Function) According to such a pneumatic radial tire, even when filling with internal pressure, the edge 8h of the shoulder block 8a on the tread center side and the second block 7a, as shown in FIG. Since the step difference δ between the tire and the tread end edge 7c is maintained, even when a large road reaction force as shown by the arrow SF in the figure is applied to the tire when the vehicle is turning at high speed, The ground pressure of the edge 8b of the shoulder block 8a inevitably increases, and the edge 8
b and its neighboring portions from rising from the road surface, while the ends 8& of the second block row 7a
Since the road reaction force that forces support by 7c and its vicinity is effectively reduced, the ground contact pressure distribution of each block 7a, 8a becomes much more uniform than that of conventional tires. , block 7a,
Abnormal wear of 8a is extremely effectively prevented.

Here, even if the end edge 8b of the shoulder block 8a and its vicinity may be deformed toward the circumferential intermediate groove 4 due to the action of the road reaction force SF, each end of each block 7a, 8a may be deformed toward the circumferential intermediate groove 4. Since the step δ exists between the edges 7cBb, the second block edge 7c and its vicinity do not support a large road reaction force as in the prior art, and are sufficiently protected from damage to the second block 1a'ci. will be done.

Furthermore, when filling the tire with internal pressure, the belt that exhibits the pruning phenomenon shown in Figure 3 (a) is caused by being stretched as shown in Figure 3 (b) due to the internal pressure filling the tire. Therefore, even if the portions of the respective blocks 7a and 8a near the circumferential grooves 3 and 4 protrude toward the outer periphery, the second block 7a is protected based on its unique contour shape in the cross section in the tread width direction. , the extreme protrusion of the tread end edge 7c of the second block 7a and its vicinity is almost completely prevented, so in this case as well, substantially the same effects as described above can be brought about. The tread center side edges of blocks 7a and 8a! ! 7b
.

8b from the road surface and the tread end edge 7c of the block 7a from being rolled in, a large cornering force can be generated.

Moreover, when the edges 7b, 8b of the blocks 7a, 8a on the tread center side protrude toward the outer periphery as shown in FIG. In relation to the ability to support external forces, both protruding edges 7b are effectively prevented from rising from the road surface.

Since the ground pressure of the second block edge 7c and its neighboring parts can be advantageously increased, the second block edge 7c and its neighboring parts are more effectively protected from damage.

These problems are even more noticeable when the contour shape of the rib 9 in the cross section in the tread width direction is approximately the same as that of the second block 7a.

Here, the distance in the tread thickness direction from the extended portion of the maximum diameter contour line a of the tread end edge 7c of the second block 7a is 1 of the depth of the circumferential intermediate groove 4.
The reason why it is set to 5% or less is that if it exceeds this, the difference between the circumferential length including the edge 7c and the circumferential length including the edge 8b becomes too large. This is because large uneven wear occurs on the block, and the reason why the separation distance is set to 0.2 mm or more is because if it is less than 0.2 mm, abnormal wear on the block cannot be sufficiently prevented. be.

In addition, the second block 7a within the cross section in the tread width direction
Although it is possible to make the ring shape linear, it is preferable to make it curved in order to make the ground pressure distribution of the block 7a more uniform. That is, the edge 7b of the block 7a on the side of the center of the trunk and its vicinity inherently has a low ground pressure, and the edge 7c of the block 7a on the opposite side and its vicinity have a low ground pressure. Since the ground pressure tends to be particularly high, the ground pressure is more effectively reduced only in areas where the ground pressure is particularly high, without causing any further reduction in the ground pressure in areas where the ground pressure is low. In order to achieve this, it is preferable that the contour line shape of the second block 7a is a curved shape that is largely separated from the extended portion of the maximum diameter contour line a at the block edge 7c and its vicinity.

Furthermore, the groove wall 3a of the tread end example of the circumferential groove 3.4
, 4a is formed so as to be inclined in the direction in which the groove width gradually widens toward the tread surface, thereby increasing the rigidity of the end portion of each block defined by the groove, thereby increasing the ground contact pressure in that portion. be able to. In this case, by setting the angle of intersection of the expanding inclined portions of the groove walls 3a and 4a with the normal line of the tread surface to be 20 to 50 degrees, the rigidity of each block end portion described above can be effectively increased. ,
It becomes possible to effectively suppress deformation of those parts.

In this way, in this pneumatic radial tire, the external force supporting load on the tread end edge 7c of the second block 7a and its vicinity is reduced, so damage to these parts is effectively prevented, and the maximum cornering speed is reduced. Even when force is generated, unlike conventional tires, this part does not wrap around, so it can provide high steering stability from low cornering force to maximum cornering force. It can also greatly improve road grip.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a tread pattern and a cross-sectional view in the tread width direction showing an embodiment of the present invention.

Note that the internal reinforcement structure of the tire is the same as that of a radial tire for boat fishing, so it is not shown in the drawings, but here a belt consisting of two steel belt layers and one nylon cap layer is used. shall be taken as a thing.

In this example, where the size is 225150 V R16 and the trend tread width is 186 mm, one circumferential thin groove 2 is formed in the center of the tread tread portion 1 and extends linearly in the tire circumferential direction. groove width of 4.5 m
m, the groove width of the circumferential large grooves 3 extending on each side of the narrow grooves 2 is 9.5 mm, and the groove width of the circumferential intermediate grooves 4 extending at a position closer to the tread end than each of these thick grooves 3 is 9.5 mm. Groove width 7.0
mm, and the groove width of the width direction groove 5 extending from the circumferential thick groove 3 to the tread end in a substantially "H" shape when viewed from the front of the installed tire is 7.0 mm, and each of the second block rows 7 The outline shape of the block 7a in the cross section in the tread width direction is defined as the edge 7b of the block 7a on the tread center side.
is located on the maximum diameter contour line a of the entire tread surface,
The portion located closer to the tread end than the end edge 7b is shaped so as to be gradually separated from the extended portion of the maximum diameter contour line a as the distance from the end edge 7b increases.

Also, here, the outline shape is an arc shape with the same radius of curvature (1000 mm) as the radius of curvature of the maximum diameter part, and the maximum separation distance of the block outline from the extension of the maximum diameter outline a is 0. By setting it to .8 mm,
10% of the circumferential intermediate groove 4 with a depth of 8.0 mm.
shall be.

Further, in this example, in the respective circumferential grooves 3 and 4 adjacent to the tread center side of the second block 7a and the shoulder flock 8a, the groove walls 3a and 4a located at the tread end of each of the grooves are The groove width is formed by tilting in a direction in which the groove width gradually widens toward the tread surface from a position closer to the tread surface than the bottoms 3b and 4b, and the normal line of each of these widening inclined portions to the tread surface. Let the intersection angle be 45°.

Here, the inner end in the radial direction of the tire of the expanding inclined portion is in the range of 10 to 70%, particularly 20 to 50%, of the groove depth of the groove bottoms 3b and 4b of the circumferential grooves 3 and 4. It is preferable to locate it in .

In other words, when the inner end position of the tire in the radial direction of the expansion slope portion is set to less than 10% of the groove depth, it approximates the conventional technology too much and cannot bring about the desired effect, and vice versa. On the other hand, if the position exceeds 70%, the expansion slope portion becomes narrow, making it impossible to secure a necessary and sufficient slope surface, and the effect cannot be expected.

Further, preferably, the groove width in the circumferential direction 13.4 is 3 to 3.
By setting it within the range of 18 mm, it is possible to effectively achieve both improvement in wet water drainage during cornering and an increase in cornering force, in other words, prevention of abnormal wear. That is, if it is less than 3 mm, it is virtually impossible to form the required expanding sloped portion in relation to the groove depth, and if it exceeds 18n+m, the expanding sloped portion 8 becomes a drag against the deformation of the block. Even if this occurs, the groove width becomes too wide, or in other words, the block width becomes too small, and it is difficult to prevent uneven wear by controlling the movement of each block as a unit, which is difficult to do as in the conventional example. Block deformation will be performed.

Using the tires constructed as described above, we conducted actual vehicle driving on circuits to quantitatively and qualitatively evaluate the wear, grip, and other maneuverability, and also used a Frandheld testing machine to When we measured the magnitude of the cornering force relative to the slip angle, the wear resistance of the second block was found to be as follows: The amount of step difference in the radial direction of the arcuate contour line in the cross section in the tread width direction with respect to the edge is 1.0 mm in the invention tire, whereas
Conventional tires had a diameter of 4.0 mm. Here, in the invention tire, the tread end side edge of the second block is formed such that the tread end side edge of the second block is
From the extension of the maximum diameter contour line of the entire tread surface, 0
．． In the conventional tire, each widthwise edge of the second block was positioned on the maximum diameter contour of the entire tread surface.

Furthermore, the maximum cornering force of the invented tire increased by about 5% compared to that of the conventional tire, and furthermore, the cornering force of the invented tire decreased extremely slowly even when the slip angle limit was exceeded. confirmed.

Furthermore, the tire's road surface grip has clearly improved compared to conventional tires in terms of driving feeling, and the grip limit has been increased for both steering response and steering stability, and the cornering force This has resulted in a significant improvement over conventional tires.

(Effects of the Invention) Thus, according to the present invention, by specifying the contour shape of at least the second block in the cross section in the tread width direction, the block can be brought into contact with the ground with sufficiently uniform ground pressure over the entire block. , it is possible to sufficiently prevent abnormal wear of the block during high-speed cornering of the vehicle, and generate excellent road grip and high cornering force.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing one embodiment of the present invention, Fig. 2 is a partial cross-sectional view in the tread width direction showing a state of internal pressure filling, and Fig. 3 is similar to Fig. 2 showing a state before and after filling of internal pressure. FIG. 4 is a diagram showing the contour shape of the tread surface in a cross section in the tread width direction. FIG. 5 is a diagram showing a deformed state of the conventional tire. 1... Tread tread portion 2... Circumferential narrow groove 3... Circumferential large groove 3a, 4a... Groove wall 3b, 4b... Groove bottom 4... Circumferential intermediate groove 5... Width direction groove 7.8... Block rows 7a, 8a... Blocks 7b, 7c, 8b... Flock edge 9... Rib

Claims (1)

[Claims] 1. Three or more circumferential grooves formed in the tread surface and extending in the tire circumferential direction, and partitioned between these circumferential grooves and between the circumferential grooves and the tread end. A pneumatic radial tire comprising a plurality of land rows, at least in a tread region located on the outside of the vehicle of the tire when mounted on a vehicle, also at least in a tread region closest to the tread edge. The second land area adjacent to the tread center side of the shoulder land area located at the
The edge on the center side of the tread in the cross section in the tread width direction,
The tread surface is located on the maximum diameter contour of the entire tread surface, and the portion located closer to the tread end than the edge thereof is gradually separated from the extended portion of the maximum diameter contour as the distance from the edge increases. Pneumatic radial tire. 2. The pneumatic radial tire according to claim 1, wherein the contour line of at least the second land portion is formed in a curved shape within the cross section in the tread width direction. 3. In addition to the second land part, in the third land part adjacent to the tread center side of this second land part, the edge of the third land part on the tread center side in the cross section in the tread width direction is Along with positioning it on the maximum diameter contour line,
3. The pneumatic radial tire according to claim 1, wherein a portion located closer to the tread end than the end edge thereof is gradually spaced apart from an extended portion of the maximum diameter contour line as the distance from the end edge increases. 4. At least in the circumferential groove adjacent to the tread center side of the second land part, the groove wall located on the tread end side is increased in groove width from a position closer to the tread surface than the groove bottom toward the tread surface. The pneumatic radial tire according to any one of claims 1 to 3, wherein the pneumatic radial tire is formed so as to be inclined in a direction that gradually expands.