CN104908526A - Pneumatic tyre - Google Patents

Abstract

The invention provides a pneumatic tyre with enhanced handling stability and non-skid property. The pneumatic tyre is provided with a straight rib (3) configured on the central side of a tyre surface and circumferentially and continuously extending along the tyre; and a middle pattern block (4) adjacent with the straight rib (3) on the axial outside of the tyre. The end portion (4E) on the firstly landing side of the middle pattern block (4) is in connection with the straight rib (3) through a connection part (5). Inclined transverse furrows (7) dividing the middle pattern block (4) possess a first inclined furrow portion (7A) extending along the straight rib (3), and a second inclined furrow portion (7B) connected to the end portion of a rear landing side of the first inclined furrow portion (7A). in the largest width portion (Pw) of the first inclined furrow portion (7A), a furrow width is greater than a furrow depth.

Description

pneumatic tire

technical field

The present invention relates to a pneumatic tire with improved steering stability and antiskid performance (particularly antiskid performance under high load such as cornering).

Background technique

As a conventional tread pattern of a pneumatic tire, a tread pattern provided with a plurality of circumferential main grooves extending in the tire circumferential direction and a plurality of oblique lateral grooves extending across the circumferential main grooves is generally known. In such a tread pattern, the water discharge toward the front and rear direction of the tire is mainly performed by the circumferential main groove, and the water discharge is performed toward the side of the tire by the inclined lateral groove, thereby ensuring the water discharge performance of the tire (for example, refer to Patent Document 1 .).

In a tire having such a tread pattern, it is useful to increase the groove area ratio of the tread surface by enlarging the groove width or the like, that is, a so-called negative ratio, as means for improving drainage performance. However, if the negative ratio is only increased, block rigidity decreases, and sufficient steering stability performance cannot be obtained. In addition, it is also clear that if the blocks are made smaller by increasing the negative ratio, the blocks are easily deformed to collapse during wet driving, thereby clogging the grooves and deteriorating drainage.

Patent Document 1: Japanese Patent Laid-Open No. 2005-35334

Contents of the invention

The present invention focuses on the fact that the pattern block collapses and deforms when driving on a wet road, and the groove is blocked to make the anti-skid performance worse. (especially anti-skid performance under high loads such as cornering) pneumatic tires.

The pneumatic tire of the present invention is characterized in that,

have:

a straight rib disposed on the tread center side and extending linearly and continuously in the tire circumferential direction; and

a middle block, which is divided by oblique transverse grooves arranged at intervals along the tire circumferential direction, and adjacent to the above-mentioned straight rib on the outer side of the tire axial direction,

An end portion of the middle block on the ground-first side is connected to the straight rib via a connecting portion,

And the above-mentioned inclined lateral groove has: a first inclined groove portion extending along the above-mentioned straight rib; Tilting outward towards the tire axis,

In addition, the first inclined groove portion has a maximum width portion where the groove width becomes the largest, and in the maximum width portion, the groove width is equal to or greater than the groove depth.

In the pneumatic tire according to the present invention, preferably, the rib width of the straight rib is larger than the groove depth of the groove adjacent to the straight rib.

In the pneumatic tire according to the present invention, it is preferable that, in a circumferential section passing through the groove bottom of the first inclined groove, the cross-sectional area Sa of the connecting portion is equal to the cross-section between the cross-sectional area Sa and the first inclined groove. 10% or more of the sum of the areas Sb (Sa+Sb).

In the pneumatic tire according to the present invention, it is preferable that the height from the groove bottom of the first inclined groove to the outer surface of the connecting portion is the same as the height from the groove bottom of the first inclined groove to the straight rib and the middle block. The outer surfaces are of equal height.

In the pneumatic tire according to the present invention, preferably, the groove width in the tire axial direction of the first inclined groove portion gradually increases toward the rear landing side, and the end portion on the rear landing side forms the maximum width portion.

In the pneumatic tire according to the present invention, it is preferable that the middle block has a sipe, and the sipe is inclined toward the rear landing side at an angle of 45 to 90 degrees relative to the circumferential line and is inclined outward in the tire axial direction.

The tire axial force (lateral force) is applied to the tread portion during cornering. In particular, in a pattern assuming a wet road surface, the negative ratio is increased in order to secure the groove volume, so that the blocks are formed relatively small. Therefore, the vehicle cannot withstand the above-mentioned lateral force, and the groove tends to be blocked during running, thereby degrading the anti-skid performance. Therefore, in the present invention, the straight rib extending linearly in the tire circumferential direction is connected to the adjacent middle block at the end portion on the ground-first side of the middle block. Thereby, the collapse of the middle block is suppressed, and as a result, the decrease in the groove volume of the first inclined groove portion due to the collapse of the block can be suppressed to a minimum.

However, since the deformation of the middle block does not completely disappear, the effect cannot be achieved when the first inclined groove portion is clogged due to slight deformation. In addition, the amount of deformation of the block in the lateral direction is not greater than the groove depth even at its maximum. Therefore, in the present invention, in the maximum width portion of the first inclined groove portion, the groove width is greater than or equal to the groove depth to ensure anti-skid performance. .

Description of drawings

Fig. 1 is a developed view showing a tread pattern of an example of a pneumatic tire of the present invention.

Figure 2 is an enlarged view of its part.

FIG. 3 is a BB sectional view of FIG. 2 .

Fig. 4 is an AA sectional view of Fig. 2 .

Fig. 5 is a developed view showing a tread pattern of another example of the present invention.

Detailed ways

Hereinafter, embodiments of the present invention will be described in detail.

As shown in FIG. 1 , a pneumatic tire 1 of the present invention includes, on a tread portion 2 , a straight rib 3 disposed on the tread center side and extending linearly and continuously along the tire circumferential direction; The rib 3 adjoins the middle block 4 . Furthermore, the end portion 4E on the ground-first side of the middle block 4 is connected to the above-mentioned straight rib 3 via the connection portion 5 .

Specifically, the pneumatic tire 1 of this example includes, on the tread portion 2 , for example, two circumferential main grooves 6 arranged at the center of the tread and extending linearly and continuously in the tire circumferential direction; A plurality of oblique lateral grooves 7 are arranged on the axially outer side at intervals along the tire circumferential direction.

The inclined lateral groove 7 has a first inclined groove portion 7A extending in the tire circumferential direction along the circumferential main groove 6 at a position away from the circumferential main groove 6 ; and an end portion Pr on the rear landing side of the first inclined groove portion 7A. The second inclined groove portion 7B is connected and inclined outward in the tire axial direction toward the rear landing side. Then, the above-mentioned straight rib 3 is formed between the above-mentioned circumferential main groove 6 and the first inclined groove portion 7A. Furthermore, the end portion Pf on the ground-first side of the first inclined groove portion 7A is separated from the adjacent inclined lateral groove 7 in the circumferential direction, and the above-mentioned connecting portion 5 is formed at the separated portion.

As shown in FIG. 2 , in this example, the inner edge ei in the tire axial direction of the first inclined groove portion 7A extends parallel to the circumferential main groove 6 , and the groove width W7 in the tire axial direction of the first inclined groove portion 7A increases as the direction increases. Gradually increase after landing on the side of the ground. Accordingly, the groove center line of the first inclined groove portion 7A is inclined at an angle α of, for example, 10 degrees or less with respect to the circumferential line. And since the aforementioned groove width W7 gradually increases toward the rear landing side, the rear landing side end Pr of the first inclined groove portion 7A forms the maximum width portion Pw. In addition, the groove width W7 of the first inclined groove portion 7A may be constant, and in this case, the entire first inclined groove portion 7A forms the maximum width portion Pw.

Furthermore, as shown in FIG. 4 , in the above-mentioned maximum width portion Pw, the groove width W7 of the first inclined groove portion 7A is set to be greater than or equal to the groove depth H7 , preferably larger than the groove depth H7 . The rib width W3 of the straight rib 3 is preferably larger than the groove depth H7 of the first inclined groove portion 7A and the groove depth H6 of the circumferential main groove 6 adjacent to the straight rib 3 . In addition, when the rib width W3 is changed, the maximum width is set to the rib width W3.

In this way, the straight rib 3 and the middle block 4 are connected via the connecting portion 5 . Therefore, the collapse of the middle block 4 caused by the lateral force can be suppressed, so that the steering stability can be improved. In addition, since the decrease in the groove volume of the first inclined groove portion 7A caused by the collapse is minimized, the decrease in drainage performance is also minimized. In addition, since the deformation amount of the blocks in the lateral direction is at most below the groove depth, W7≥H7 is formed to ensure the anti-skid performance.

From the viewpoint of ensuring steering stability, as shown in FIG. 3 , it is preferable that the height H5 from the groove bottom 7As of the first inclined groove portion 7A to the outer surface of the connecting portion 5 be the same as the height H5 to the outer surface of the straight rib 3 and the middle block 4 . The heights H3 and H4 are equal. That is, it is preferable that the outer surface of the connecting portion 5 is flush with the outer surfaces of the straight rib 3 and the middle block 4 . Assuming that the height H5 is smaller than the heights H3 and H4, that is, if the connecting portion 5 is formed as a tie, the ground contact area and the block rigidity are reduced, and sufficient steering stability cannot be ensured.

Furthermore, the connecting portion 5 is preferably formed by a main body portion 5A having the same height as the straight rib 3 and the middle block 4, and an inclined portion 5B whose height gradually decreases from the main body portion 5A to the groove bottom 7As of the first inclined groove portion 7A, Furthermore, the circumferential length LB of the inclined portion 5B is made larger than the circumferential length LA of the main body portion 5A. Thereby, the influence of the connection part 5 on drainage performance is further reduced, and anti-slip performance is ensured.

And, as shown in the figure, in the circumferential cross section passing through the groove bottom 7As of the first inclined groove portion 7A, it is preferable that the cross-sectional area Sa of the above-mentioned connecting portion 5 is equal to the cross-sectional area Sa of the first inclined groove portion 7A. 10% or more of the sum of Sb (Sa+Sb). When the cross-sectional area Sa is less than 10% of the sum (Sa+Sb), the reinforcing effect of the connecting portion 5 becomes insufficient, making it difficult to ensure steering stability. In particular, from the viewpoint of steering stability and water drainage, the lower limit of the cross-sectional area Sa is preferably 25% or more of the sum (Sa+Sb), and the upper limit is preferably 50% or less.

As shown in FIG. 2 , the above-mentioned middle block 4 has at least one (three in this example) sipe 10 . The sipe 10 is inclined outward in the tire axial direction toward the rear landing side at an angle θ of 45 to 90 degrees with respect to the circumferential line. Since such sipe 10 is inclined at an angle θ of 45 to 90 degrees, lateral rigidity of the middle block 4 can be ensured. In addition, since it is inclined toward the rear landing side and outward in the tire axial direction, water can be discharged axially outward to contribute to an improvement in anti-skid performance.

Further, the second inclined groove portion 7B extends outward in the tire axial direction beyond the tread edge Te (shown in FIG. 1 ). The angle β of the second inclined groove 7B with respect to the circumferential line is larger than the angle α of the first inclined groove 7A, and preferably gradually increases toward the outer side in the tire axial direction in the range of 30 to 90 degrees. The second inclined groove portion 7B cooperates with the first inclined groove portion 7A to allow water to flow out from the center of the tread to the outside of the ground contact surface, thereby minimizing the influence of the connecting portion 5 on drainage.

Furthermore, in this example, between the tread edge Te and the circumferential main groove 6 , the connecting groove 11 sequentially connecting the circumferentially adjacent second inclined groove portions 7B, 7B is arranged. In this example, an example is disclosed in which the connection grooves 11 are inclined at a small angle γ of, for example, 15 degrees or less with respect to the circumferential line, but the connection grooves 11 may also be arranged at γ=0 degrees as if forming one straight groove. in a row.

Another example of the present invention is shown in FIG. 5 . In this example, the circumferential main groove 6 is not formed, but the straight rib 3 is formed between the first inclined groove portions 7A, 7A on both sides in the tire axial direction.

As mentioned above, although the especially preferable embodiment of this invention was described in detail, this invention is not limited to embodiment shown in figure, It can deform|transform and implement in various forms.

Example

Based on the pattern in Figure 1, the pneumatic tire (330/710R18) was trial-manufactured according to the specifications in Table 1, and the anti-skid performance and handling stability of each trial tire were tested and compared. Except for the specifications listed in Table 1, the other specifications are substantially the same.

In addition, Conventional Example 1 is configured such that, in the pattern of FIG. 1 , there is no connection portion 5 and the first inclined groove portions 7A, 7A are connected to each other. Conventional Example 2 is configured such that, in the pattern of FIG. 1 , block rows are formed instead of the straight ribs 3 .

(1) Handling stability:

Under the conditions of the rim (18×13.0J) and internal pressure (180kPa), the test tires were installed on the four wheels of the vehicle (3400cc FR car), driven by a driver on the test track on the asphalt road, and The sensory evaluation by the driver was performed with an index of 100 in Conventional Example 1. A larger numerical value indicates better steering stability.

(2) Anti-skid performance:

Using the vehicle described above, a turn was made on a runway having a puddle of 5 mm of water film, and the turn G was measured. The evaluation is represented by an index with Conventional Example 1 being 100. The larger the value, the higher the turning G and the better the anti-skid performance.

Table 1

As shown in the table,

In Conventional Example 2, the block rows are formed instead of the straight ribs 3, so that the water drainage is slightly improved, but it is not stable and the steering stability is lowered.

In Comparative Example 1, since the maximum groove width W7 of the first inclined groove portion 7A was smaller than the groove depth H7, the groove was clogged by a lateral force, resulting in poor drainage.

In Example 1, the anti-skid performance and steering stability were improved.

In Embodiment 2, the rib width W3 of the straight rib 3 is narrow, so the straight rib 3 is prone to kinks, and the anti-skid performance and handling stability are slightly lower than those in Embodiment 1.

In Example 3, the cross-sectional area Sa of the connecting portion 5 is small, so the effect of suppressing the collapse of the middle block 4 is weakened, and the antiskid performance and steering stability are slightly lower than those in Example 1.

In Example 4, the cross-sectional area Sa of the connecting portion 5 is slightly smaller, but higher than that of Example 3, so the anti-skid performance and handling stability are slightly restored compared to Example 3.

In Example 5, since the groove volume of the first inclined groove portion 7A decreases due to the increase in the cross-sectional area Sa of the connecting portion 5, the anti-skid performance decreases, but the block rigidity increases, thereby improving the steering stability.

In Example 6, since the cross-sectional area Sa of the connecting portion 5 was further increased, compared with Example 5, the tendency of the decrease in anti-skid performance and the improvement in steering stability was further strengthened.

In Example 7, the height H5 of the connecting portion 5 is low, so the effect of suppressing the collapse of the middle block 4 is weakened, and the antiskid performance and steering stability are slightly lower than those of Example 1.

In Example 8, the groove width of the first inclined groove portion 7A is constant, but there is no particularly large variation.

In Example 9, since the groove width of the first inclined groove portion 7A gradually decreases toward the rearward landing side, the water flowing in from the first landing side tends to overflow, thereby degrading drainage.

In Example 10, the angle θ of the sipe 10 exceeds 90° (that is, it inclines to the ground-first side), so that the drainage is directed toward the tire center side, and the drainage performance is reduced.

In Example 11, the angle θ of the sipe 10 is 90°, the tire axial rigidity of the middle block 4 is maintained high, and thus the steering stability is improved.

In Example 12, the angle θ of the sipe 10 is 45°, and the tire axial rigidity of the middle block 4 is slightly lowered, so the antiskid performance and steering stability are slightly lower than those of Example 1.

In Example 13, the angle θ of the sipe 10 is 30°, and the tire axial rigidity of the middle block 4 is further lowered, so the antiskid performance and steering stability are further lowered than in Example 12.

Explanation of reference signs

1...Pneumatic tire; 3...Straight rib; 4...Middle block; 4E...The end of the first landing side; 5...Connecting part; 7...Inclined transverse groove; 7A. ..first inclined groove; 7B...second inclined groove; 10...sipe; Pw...maximum width portion.

Claims (6)

1. A pneumatic tire, characterized in that, have: a straight rib disposed on the tread center side and extending linearly and continuously in the tire circumferential direction; and a middle block, which is divided by oblique transverse grooves arranged at intervals in the tire circumferential direction, and adjoins said straight rib on the outside in the tire axial direction, The end portion of the middle block on the ground-first side is connected to the straight rib via a connecting portion, And the inclined lateral groove has: a first inclined groove portion extending along the straight rib; and a second inclined groove portion connected to the rear landing side end of the first inclined groove portion and facing toward Rear landing side and inclined to the outside of the tire axis, And the first inclined groove portion has a maximum width portion where the groove width becomes the largest, and the groove width is equal to or greater than the groove depth in the maximum width portion. 2. The pneumatic tire according to claim 1, wherein: The rib width of the straight rib is larger than the groove depth of the groove adjacent to the straight rib. 3. The pneumatic tire according to claim 1 or 2, wherein: In a circumferential section passing through the groove bottom of the first inclined groove, the cross-sectional area Sa of the connecting portion is equal to the sum of the cross-sectional area Sa and the cross-sectional area Sb of the first inclined groove (Sa+Sb) 10% or more. 4. The pneumatic tire according to any one of claims 1 to 3, wherein: The height from the bottom of the first inclined groove to the outer surface of the connecting portion is equal to the height from the bottom of the first inclined groove to the outer surface of the straight rib and the intermediate block. 5. The pneumatic tire according to any one of claims 1 to 4, wherein: A groove width in the tire axial direction of the first inclined groove portion gradually increases toward the rear-landing side, and an end portion of the rear-landing side forms the maximum width portion. 6. The pneumatic tire according to any one of claims 1 to 5, wherein: The middle block has a sipe, and the sipe is inclined toward the rear landing side at an angle of 45 to 90 degrees with respect to the circumferential line and toward the tire axially outer side.