JP2007331411A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire for compatibly attaining eccentric wear resistance and hydroplaning resistance resulting from the structure of the tire. <P>SOLUTION: The pneumatic tire comprises a belt layer provided on the tire-radial-direction outside of a crown portion of a carcass ply toridally extending between a pair of bead cores, a tread part provided on the tire-radial-direction outside beyond the belt layer and having a plurality of land trains partitioned with a plurality of peripheral grooves extending to a tire peripheral direction, a plurality of first lug grooves provided in at least one of the land trains between the peripheral grooves on the tire-cross-direction outside, and a plurality of second lug grooves provided therein which have greater angles to the tire peripheral direction than the first lug grooves and different widths from the first lug grooves. It compatibly attains eccentric wear resistance and hydroplaning resistance resulting from the structure of the tire. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a pneumatic tire. When a single tread pattern is lined up in several sizes, the design of the groove shape arranged in the tread portion is changed according to the structural characteristics of the tire. It is intended to solve the structure-specific problems while having the same product line.

A typical tread pattern of a conventional pneumatic tire is that when two types of lug grooves having different angles with respect to the tire circumferential direction exist on the same land portion row, the relationship between the groove widths of these lug grooves is There is no change in any size on the size lineup, but due to the difference in input from the road surface to the tire, the one with low flatness compared to the one with high flatness can add a circumferential spiral belt, Increase the number of crossed steel belts. (For example, Patent Document 1)
Japanese Patent Laid-Open No. 08-142612

Now, when a plurality of sizes are lined up in the same product series, a similar tread pattern is applied, and the tire structure is changed according to the difference in input from the road surface.
However, in tires with a high flatness ratio, the spring stiffness as a tire is low, so reducing the number of belts reduces the out-of-plane rigidity and ensures steering stability performance. Since the contact shape is round (the difference in contact length between the center and the shoulder is large), the hydroplaning performance is high, but the uneven wear resistance is disadvantageous (the situation where shoulder drop wear is likely to occur) There is a problem.
Also, tires with low flatness have high spring rigidity as tires, so increasing the number of belts improves out-of-plane rigidity and ensures steering stability performance. Since the ground contact shape is a square shape (the difference in contact length between the center and the shoulder is small), the uneven wear resistance is high, but the hydroplaning performance is disadvantageous.

  For this reason, even in a pneumatic tire that employs the groove arrangement as described above, there is a problem that uneven wear tends to occur depending on the structure of the tire and the hydroplaning performance cannot be exhibited.

  In view of the above facts, an object of the present invention is to provide a pneumatic tire having both uneven wear resistance and hydroplaning performance due to the tire structure.

  In order to achieve the above object, a pneumatic tire according to claim 1 of the present invention includes a belt layer provided on the outer side in the tire radial direction of a crown portion of a carcass ply extending in a toroidal shape between a pair of bead cores, and the belt Between the tread portion having a plurality of land portion rows provided on the outer side in the tire radial direction from the layer and partitioned by a plurality of circumferential grooves extending in the tire circumferential direction, and the circumferential groove on the outermost side in the tire width direction A plurality of first lug grooves provided in at least one of the land portion rows and the land portion row provided with the first lug grooves, the angle with respect to the tire circumferential direction being the first lug grooves A plurality of second lug grooves having a groove width different from that of the first lug groove are provided.

Next, the effect of the pneumatic tire according to claim 1 will be described.
From the angle with respect to the tire circumferential direction, the first lug groove mainly contributes to the hydroplaning performance, and the second lug groove mainly contributes to the uneven wear resistance (shoulder wear resistance). By providing the first lug groove and the second lug groove in at least one row of the land portion rows between the outermost circumferential grooves in the tire width direction (hereinafter referred to as a tread center portion), the ground contact shape is In a tire with a rounded structure, the second lug groove reduces the block rigidity of the land portion row of the tread center portion, and the amount of wear of the tread center portion and the tread shoulder portion (between the tread center portion and both tread ground contact ends). ) To improve the uneven wear resistance (shoulder wear resistance), and in tires with a structure where the ground contact shape is square, the first lug groove is in the tire traveling direction when traveling on a wet road surface. Contributes to eliminating road surface water into the circumferential grooves and improves hydroplaning performance.
From the above, the first lug groove and the second lug groove achieve both unbalanced wear resistance and hydroplaning performance due to the tire structure.
In addition, by changing the design of the width of each of the first lug groove and the second lug groove according to the structure of the tire, it is possible to further improve the hydroplaning performance and uneven wear resistance performance. Can be further achieved.

  Here, the tread grounding end means that a pneumatic tire is mounted on a standard rim specified in JATMA YEAR BOOK (2006 edition, Japan Automobile Tire Association Standard) and applied size / ply in JATMA YEAR BOOK Filling 100% of the air pressure (maximum air pressure) corresponding to the maximum load capacity in the rating (internal pressure-load capacity correspondence table in bold) as the internal pressure, and the outermost ground contact part in the tire width direction when the maximum load capacity is loaded Point to. In addition, when TRA standard and ETRTO standard are applied in a use place or a manufacturing place, it follows each standard.

  A pneumatic tire according to a second aspect of the present invention is the pneumatic tire according to the first aspect, wherein an angle formed by the tire circumferential direction of the first lug groove is 0 to 45 °, and the second lug The angle between the groove and the tire circumferential direction is 45 to 90 °.

Next, the effect of the pneumatic tire of Claim 2 is demonstrated.
If the angle of the first lug groove with respect to the tire circumferential direction exceeds 45 °, the angle with respect to the tire circumferential direction becomes too large to improve the hydroplaning performance.
Further, if the angle of the second lug groove with respect to the tire circumferential direction is less than 45 °, the corner of the land portion row becomes too acute and the uneven wear resistance performance deteriorates.
Therefore, it is preferable that the angle between the first lug groove and the tire circumferential direction is 0 to 45 °, and the angle between the second lug groove and the tire circumferential direction is 45 to 90 °.

  The pneumatic tire according to claim 3 of the present invention is characterized in that, in the pneumatic tire according to claim 1 or 2, the groove width of the second lug groove is wider than that of the first lug groove.

Next, the effect of the pneumatic tire according to claim 3 will be described.
Usually, in the case of a belt structure with only a belt layer, the grounding shape tends to be a round grounding shape, and the width of the second lug groove is wider than the width of the first lug groove, so that The block rigidity of the row is efficiently reduced to balance the wear amount of the tread center portion and the wear amount of the tread shoulder portion, thereby further improving the uneven wear resistance (shoulder fall wear resistance).

  A pneumatic tire according to a fourth aspect of the present invention is the pneumatic tire according to the first or second aspect, wherein the pneumatic tire has a belt reinforcing layer between the belt layer and the tread portion, and the first lug groove. Further, the groove width of the second lug groove is narrow.

Next, the effect of the pneumatic tire of Claim 4 is demonstrated.
In the case of the belt structure in which the belt reinforcing layer is provided, the grounding shape is a square grounding shape as compared with the case where the belt reinforcing layer is not provided. Therefore, the groove width of the first lug groove is set to be equal to that of the second lug groove. By taking it wider than the groove width, the amount of water on the road surface in the tire advancing direction being excluded to the circumferential groove when running on a wet road surface is increased, so that the hydroplaning performance is further improved.

  The pneumatic tire of the present invention can achieve both uneven wear resistance and hydroplaning performance due to the tire structure.

[First Embodiment]
(Configuration) Next, a first embodiment of the pneumatic tire of the present invention will be described with reference to FIGS. Note that the pneumatic tire 10 of the present embodiment (hereinafter simply referred to as the tire 10) is a summer tire having a tire size of 155 / 70R13.
As shown in FIG. 1, the tire 10 includes a pair of bead cores 12, a carcass ply 14 extending and straddling the bead core 12 in a toroid shape, and a belt layer 16 provided on the outer side in the tire radial direction of the crown portion of the carcass ply 14. And a tread portion 18 provided on the outer side in the tire radial direction from the belt layer 16. The belt layer 16 of the present embodiment is formed by stacking two belt plies 16A formed by arranging a plurality of steel cords in parallel and embedding them in a covering rubber.

(Circumferential groove, land part row)
As shown in FIG. 2, the tread pattern of the tire 10 is a tread pattern in which a rotational direction in which the left and right sides of the tread pattern are symmetrical with respect to one point on the equator plane CL (one-dot chain line) is not specified. In addition, the expression showing the upper, lower, left, and right directions here means the upper, lower, left, and right directions as viewed in the drawing.
A tread tread surface 18S of the tread portion 18 is provided with a circumferential groove 20 provided on the equator plane CL and extending along the equator plane CL. A circumferential groove 22L extending in the tire circumferential direction is provided on the left side of the circumferential groove 20, and a circumferential groove 22R extending in the tire circumferential direction is provided on the right side. The land portion rows formed between the circumferential groove 20 and the circumferential grooves 22L and 22R are referred to as center land portion rows 24L and 24R, respectively, and the land formed on the outer side in the tire width direction from the circumferential grooves 22L and 22R. The partial rows are referred to as shoulder land portion rows 26L and 26R, respectively.
The tread surface 18S indicates a region between the tread grounding ends 18E (two-dot chain line in FIG. 2). A region between the circumferential grooves 22L and 22R is referred to as a tread center portion 40, and a region between the tread center portion 40 and both tread grounding ends 18E is referred to as a tread shoulder portion 42.

(Lug groove)
As shown in FIG. 2, the center land portion row 24L is provided with a lug groove 28L extending in a curved shape from the upper left to the lower right. One end of the lug groove 28L communicates with the circumferential groove 22L, and the other end terminates in the center land portion row 24L. The center land portion row 24L is provided with a lug groove 30L extending linearly from the upper left to the lower right. The angle of the lug groove 30L with respect to the tire circumferential direction is equal to or greater than the lug groove 28L. One end of the lug groove 30L communicates with the circumferential groove 22L and the other end communicates with the lug groove 28L.
Further, the groove width of the lug groove 30L is set wider than the groove width of the lug groove 28L, and the angle of the lug groove 28L with respect to the tire circumferential direction preferably satisfies 0 to 45 °, and the lug groove 30L with respect to the tire circumferential direction The angle preferably satisfies 45 to 90 °.

The center land portion row 24R is provided with a lug groove 28R extending in a curved shape from the lower right to the upper left. One end of the lug groove 28R communicates with the circumferential groove 22R, and the other end terminates in the center land portion row 24L. The center land portion row 24R is provided with a lug groove 30R extending linearly from the lower right to the upper left. The angle of the lug groove 30R with respect to the tire circumferential direction is equal to or greater than the lug groove 28R. One end of the lug groove 30R communicates with the circumferential groove 22R and the other end communicates with the lug groove 28R.
Further, the groove width of the lug groove 30R is set wider than the groove width of the lug groove 28R, and the angle of the lug groove 28R with respect to the tire circumferential direction preferably satisfies 0 to 45 °, and the lug groove 30R with respect to the tire circumferential direction is satisfied. The angle preferably satisfies 45 to 90 °.

The shoulder land portion row 26L is provided with lug grooves 32L extending in the tire width direction. One end of the lug groove 32L communicates with the circumferential groove 22L, and the other end terminates in the shoulder land portion row 26L.
The shoulder land portion row 26R is provided with lug grooves 32R extending in the tire width direction. One end of the lug groove 32R communicates with the circumferential groove 22R, and the other end terminates in the shoulder land portion row 26R.

(Operation) Next, the operation of the tire 10 of the first embodiment will be described.
The flatness of the tire 10 is 70%, and the belt structure has only two belt plies 16A overlapped, so that the ground contact shape is a round contact shape as shown in FIG. That is, the contact length L1 of the center (equatorial plane CL) in the contact shape of the tire 10 (in this embodiment, the longest contact length of the center land portion row is L1) and the shoulder (tread contact end 18E) in the contact shape. This means that the difference from the ground contact length L2 is large. In the case of such a ground contact shape, water on the road surface in the tire traveling direction at the time of running on a wet road surface can be easily removed in the tire width direction, so that the hydroplaning performance is improved, but the tread center portion 40 and the tread shoulder portion 42 The difference in circumference increases, and uneven wear resistance (shoulder wear resistance) is disadvantageous.
However, since the lug grooves 30L and 30R lower the block rigidity of the center land portion rows 24L and 24R of the tread center portion 40, the wear amount of the tread center portion 40 and the wear amount of the tread shoulder portion 42 can be balanced. Further, uneven wear resistance (shoulder wear resistance) can be improved.
Therefore, the tire 10 can achieve both uneven wear resistance and hydroplaning performance due to the tire structure by the lug grooves 28L and 28R and the lug grooves 30L and 30R.

  If the angle of the lug grooves 28L and 28R with respect to the tire circumferential direction exceeds 45 °, the angle with respect to the tire circumferential direction becomes too large to improve the hydroplaning performance. Further, if the angle of the lug grooves 30L and 30R with respect to the tire circumferential direction is less than 45 °, the center land portion rows 24L and 24R have locations where the angles become too acute, and the uneven wear resistance performance deteriorates. Therefore, the angle formed between the lug grooves 28L and 28R and the tire circumferential direction is preferably 0 to 45 °, and the angle formed between the lug grooves 30L and 30R and the tire circumferential direction is preferably 45 to 90 °.

  Further, by making the groove widths of the lug grooves 30L and 30R wider than the groove widths of the lug grooves 28L and 28R, the block rigidity of the center land portion rows 24L and 24R of the tread center portion 40 is efficiently reduced, and the tread center portion 40 It is possible to further improve the uneven wear resistance (shoulder fall wear resistance) by balancing the amount of wear and the wear of the tread shoulder portion 42.

[Second Embodiment]
(Configuration) Next, a second embodiment of the pneumatic tire of the present invention will be described with reference to FIGS. Note that the pneumatic tire 50 of the present embodiment (hereinafter simply referred to as the tire 50) is different from the first embodiment in terms of tire size, addition of a belt reinforcing layer, lug grooves 28L and lug grooves 30L. The relationship between the respective groove widths is different from the relationship between the respective groove widths of the lug groove 28R and the lug groove 30R. Details of the differences will be described below. In addition, the same code | symbol is attached | subjected to the same structure as 1st Embodiment, and the description is abbreviate | omitted.

  The tire size of the tire 50 is a 195 / 65R15 summer tire. As shown in FIG. 4, a belt reinforcing layer 34 is provided between the belt layer 16 and the tread portion 18 of the tire 50. The belt reinforcing layer 34 according to the present embodiment is formed by spirally winding a belt-like body in which one or a plurality of nylon cords are covered with unvulcanized covering rubber. Further, as shown in FIG. 5, the groove width of the lug groove 28L is set wider than the groove width of the lug groove 30L. Furthermore, the groove width of the lug groove 28R is set wider than the groove width of the lug groove 30R.

(Operation) Next, the operation of the second embodiment will be described.
The flatness of the tire 50 is 65%, and the belt structure includes a belt reinforcing layer 34 in which a nylon cord is spirally wound in the tire circumferential direction in addition to the belt layer 16 in which two belt plies 16A are overlapped. The grounding shape is a square grounding shape as shown in FIG. That is, the difference between the ground contact length L1 of the center in the ground contact shape of the tire 50 (in this embodiment, the longest ground contact length of the center land portion row is L1) and the ground contact length L2 of the shoulder in the ground contact shape is small. means. In the case of such a ground contact shape, the difference in circumferential length between the tread center portion 40 and the tread shoulder portion 42 is reduced, and the uneven wear resistance performance is improved, but the water on the road surface in the tire traveling direction when traveling on a wet road surface is used as the tire. It is difficult to eliminate in the width direction, resulting in a disadvantageous hydroplaning performance.
However, the lug grooves 28L and 28R contribute to the elimination of the water on the road surface in the tire traveling direction during running on the wet road surface into the respective circumferential grooves, and therefore the hydroplaning performance can be improved.
Therefore, the tire 50 can achieve both uneven wear resistance and hydroplaning resistance due to the tire structure by the lug grooves 28L and 28R.

  Further, since the groove widths of the lug grooves 28L and 28R are wider than the groove widths of the lug grooves 30L and 30R, the amount of water on the road surface in the tire advancing direction when driving on the wet road surface is increased in each circumferential groove. Further, the hydroplaning performance is further improved.

[Other Embodiments]
In the first and second embodiments, the lug groove 28L and the lug groove 30L communicate with each other. However, the lug groove 28L and the lug groove 30L may not communicate with each other. The lug groove 30L is configured not to divide the center land portion row 24L, but may be configured to divide the center land portion row 24L. Similarly, the lug groove 28R and the lug groove 30R may be configured not to communicate with each other, or the lug groove 28R and the lug groove 30R may be configured to divide the center land portion row 24R.

  In the first and second embodiments, the lug grooves 28L and 28R are configured to extend in a curved shape. However, the lug grooves 28L and 28R may be configured to extend in other shapes (for example, linear), and the lug groove 30L. And 30R was the structure extended in linear form, However, The structure extended in other shapes (for example, curvilinear form) may be sufficient.

  Furthermore, in the first and second embodiments, the tread pattern is a pattern in which the left and right sides of the tread pattern are a pattern that does not specify a rotational direction in which a point symmetric shape is formed with respect to one point on the equator plane CL. A configuration may be adopted in which the rotational direction is a symmetrical shape with the equator plane CL as the axis of symmetry, and in this case, the hydroplaning performance is further improved by the lug grooves 28L and 28R. .

(Test example)
In order to confirm the performance improvement effect of the pneumatic tire of the present invention, the pneumatic tire of the first embodiment (size 155 / 70R13) and the pneumatic tire of the second embodiment (size 195 / 65R15) ) And the tread pattern (see FIG. 2) of the pneumatic tire of the first embodiment and the pneumatic tire of the first embodiment are similar to those for the size 195 / 65R15. The comparative example 1 which makes the pneumatic tire provided with the expanded tread pattern the same product series, the pneumatic tire of 2nd Embodiment, and the tread pattern (refer FIG. 5) of the pneumatic tire of 2nd Embodiment. Pneumatic tires corresponding to Comparative Example 2 in which pneumatic tires having a tread pattern reduced to a similar size for size 155 / 70R13 are the same product line It fabricated, for each test tires, steering stability on a dry road, evaluated hydroplaning resistance performance in uneven wear resistance and wet road surface was carried out. The tire configurations of the example, comparative example 1 and comparative example 2 are shown in Table 1. Further, the steel belt having the belt structure indicates the belt ply 16A of the first embodiment, and the nylon spiral belt indicates the belt reinforcing layer 34 of the second embodiment.

There are two types of test tires, 155 / 70R13 and 195 / 65R15, and the types are summer tires. After assembling to rims with 5J-13 and 6J-15 rim widths, The test tire was mounted, and under the load condition in which 600 N was added to the weight and weight of the driver, the specified tire pressure was filled into the test tire and the following evaluation test was performed.
The uneven wear resistance performance was evaluated by measuring the wear level difference between the tread center portion and the tread shoulder portion at the time of traveling 10,000 km on the dry road.
Steering stability was evaluated by the driver's feeling when driving on dry roads.
The hydroplaning resistance was evaluated by measuring the speed at which hydroplaning occurred when traveling on a wet road with a water depth of 10 mm.
In addition, about each of these evaluation items, it evaluates as an index | exponent display which sets the value of the tire of the goods series of an Example to 100, and the one where the value is larger shall show the better result.

From the results shown in Table 1, it can be seen that the example shows that the anti-hydroplaning performance can be improved particularly in the size 195 / 65R15 while ensuring the same level of other performance as compared with the comparative example 1.
Moreover, it turns out that an Example shows that the uneven wear-proof performance in size 155 / 70R13 was able to be improved compared with the comparative example 2 while ensuring the equivalent level with another performance.
From the above, according to the present invention, the ratio of the respective groove widths of the first lug groove and the second lug groove can be obtained while holding the tread pattern having the same configuration as the same product series on the size lineup. By designing and deforming for each tire structure, both uneven wear resistance and hydroplaning performance due to the tire structure can be achieved.

It is sectional drawing along the rotating shaft of the pneumatic tire which concerns on 1st Embodiment. It is the top view showing the tread pattern of the pneumatic tire concerning a 1st embodiment. It is the figure which showed the contact shape of the pneumatic tire which concerns on 1st Embodiment. It is sectional drawing along the rotating shaft of the pneumatic tire which concerns on 2nd Embodiment. It is the top view which showed the tread pattern of the pneumatic tire which concerns on 2nd Embodiment. It is the figure which showed the contact shape of the pneumatic tire which concerns on 2nd Embodiment.

Explanation of symbols

10 Tire (Pneumatic tire)
12 bead core 14 carcass ply 16 belt layer 18 tread portion 20 circumferential groove 22 circumferential groove 24 center land portion row (land portion row)
28 lug groove (first lug groove)
30 lug groove (second lug groove)
34 Belt reinforcement layer 40 Tread center (between the outermost circumferential grooves in the tire width direction)
50 tires (pneumatic tires)

Claims (4)

A belt layer provided on the outer side in the tire radial direction of the crown portion of the carcass ply extending in a toroidal shape between the pair of bead cores;
A tread portion having a plurality of land portion rows provided on the outer side in the tire radial direction from the belt layer and partitioned by a plurality of circumferential grooves extending in the tire circumferential direction;
A plurality of first lug grooves provided in at least one row of the land portion rows between the circumferential grooves on the outermost side in the tire width direction;
Provided in the land portion row where the first lug groove is provided, an angle with respect to the tire circumferential direction is equal to or greater than the first lug groove, and a plurality of second different groove widths from the first lug groove Lug grooves,
A pneumatic tire characterized by comprising: The angle formed by the tire circumferential direction of the first lug groove is 0 to 45 °,
The pneumatic tire according to claim 1, wherein an angle between the second lug groove and the tire circumferential direction is 45 to 90 °.   The pneumatic tire according to claim 1 or 2, wherein a groove width of the second lug groove is wider than that of the first lug groove. Having a belt reinforcing layer between the belt layer and the tread portion;
The pneumatic tire according to claim 1 or 2, wherein a groove width of the second lug groove is narrower than that of the first lug groove.

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