JP2014083950A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire having excellent uneven wear resistance and week rolling resistance by optimizing structure of tread part.SOLUTION: The pneumatic tire has at least one layer of carcass as a framework toroidally across between a pair of bead parts. At a position outside of crown part of the carcass in a radial direction, is arranged: at least one layer of inclined belt layer in which a large number of codes extending with inclination relative to the tire equatorial plane are coated with rubber; and tread. At least one layer of the inclined belt layer(s) extends to outside of the grounding edge of the tread in tire width direction. At a region ranging from at a position between the grounding edge of the tread and a position corresponding to the end part in the width direction of the inclined belt layer having the longest width to a position outside in tire width direction of the end part in the width direction of the inclined belt layer having the longest width, a different kind rubber layer having superior wear resistance to the tread rubber at a region other than the region is arranged.

Description

  The present invention relates to a pneumatic tire having excellent uneven wear resistance performance at a shoulder portion and low rolling resistance.

  In recent years, development of products with a smaller environmental load has been actively conducted. This is to deal with environmental problems such as global warming, and tires are no exception. From such a viewpoint, improving the uneven wear resistance of the tire and extending the life of the tire, and reducing the rolling resistance of the tire and contributing to lower fuel consumption of the automobile are also measures against the environmental problems. Various technological developments have been made in the past.

  For example, Patent Document 1 discloses a method for improving the ground contact shape of a tire as a method for improving uneven wear resistance and reducing rolling resistance of the tire. Specifically, by increasing the tire circumferential direction tension of the circumferential belt layer in the tire width direction outer region than in the tire width direction central region, the radial difference between the tire width direction central region and the tire width direction outer region is reduced. There has been proposed a tire that is reduced and has a uniform ground contact shape. This is because, due to the difference in diameter between the center region in the tire width direction and the outer region, the shearing force in the circumferential direction becomes nonuniform in the tire width direction when the tire rolls, This is an attempt to reduce the preferential wear near the grounded end of the tread due to the shearing force. This method also contributes to reduction of rolling resistance because it reduces the shear strain of the tire.

  By the way, the wear near the ground contact edge of the tread as described above progresses outward in the tire width direction along the crown shape of the tread as the travel distance of the tire increases. In other words, the ground contact edge of the tire moves with time toward the outside in the tire width direction. Since the time until it disappears due to wear is shorter than in other areas, it has emerged as a new problem that the life until the tread reaches the end of wear becomes extremely short due to the expansion of the contact area. . Accordingly, there is a demand for a tire that is more excellent in uneven wear resistance and has a low rolling resistance that appropriately copes with the wear that progresses outward in the tire width direction with the travel distance.

JP 2011-126304 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a tire that has an appropriate tread structure, is excellent in uneven wear resistance, and has low rolling resistance.

The inventors first improved the expected performance by regulating the width end position of the belt layer of the tire to increase the rigidity of the tread shoulder portion and then regulating the arrangement of the tread rubber in the tread width direction. The knowledge that it is possible was obtained. In other words, the belt layer is extended from the ground contact end of the tire to the outside in the tire width direction, and rubber having higher wear resistance than the rubber other than the region is disposed in a region outside the tread contact end in the tire width direction. Thus, it has been found that uneven wear resistance can be improved while maintaining rolling resistance performance.
Furthermore, in the present invention, it is found that the above-described improvement can be further effectively performed by defining the thickness of the region in addition to the position in the tire width direction of the region, and the present invention is completed. It came.

The gist of the present invention is as follows.
(1) Using at least one layer of a carcass straddling a toroidal shape between a pair of bead portions as a skeleton, a large number of cords extending incline with respect to the tire equatorial plane on the radially outer side of the crown portion of the carcass A pneumatic tire in which at least one inclined belt layer coated with a tread and a tread are disposed,
At least one layer of the inclined belt layer extends from the ground contact end of the tread to the outside in the tire width direction,
On the surface of the tread, the width of the tire from the widthwise end of the maximum width layer of the inclined belt layer is between the ground contact end of the tread and the position corresponding to the width direction end of the maximum width layer of the inclined belt layer. A pneumatic tire characterized in that a dissimilar rubber layer having higher wear resistance than a tread rubber other than the region is disposed in a region up to the outer side in the direction.

  (2) The end portion of the maximum width layer of the inclined belt layer is from the contact end side of the tread to the contact end side C / 3 of the tread when the distance in the tire width direction from the contact end of the tread to the maximum width position of the tire is C. The pneumatic tire according to (1), wherein the outer end in the tire width direction of the dissimilar rubber layer is located in a range up to a contact end side C / 2 of the tread.

  (3) The thickness of the different rubber layer in the tire radial direction is from 10% to 60% of the tread rubber gauge at the end of the maximum width layer of the inclined belt layer from the tread surface toward the inner side in the tire radial direction. The pneumatic tire according to any one of (1) and (2) above, wherein

According to the present invention, by placing a rubber layer having higher wear resistance than the other regions in the tread surface layer region on the outer side in the tire width direction from the tread ground contact edge, due to the load applied to the tire during running and the stress generated during cornering The resulting wear near the tread contact edge can be prevented from spreading outward in the tire width direction, and the wear life of the tire can be extended while maintaining the rolling resistance performance of the tire.
Furthermore, the above-mentioned effect can be more reliably obtained by regulating the thickness of the different rubber layer.

It is sectional drawing of the width direction right half of the pneumatic tire which concerns on 1st Embodiment of this invention. (A) is 2nd Embodiment of this invention, (b) is width direction sectional drawing from the side part to a shoulder part of the pneumatic tire which concerns on 3rd Embodiment of this invention. It is the graph which showed the relationship between the travel distance of each test tire, and the amount of wear at the contact point Te of the tire. It is the graph which showed the relationship between the rolling resistance performance of each test tire, and the wear life of the tire at the ground contact edge Te of the tire.

DESCRIPTION OF EMBODIMENTS Hereinafter, a pneumatic tire (hereinafter, also referred to as a tire) of the present invention will be described in detail by exemplifying an embodiment thereof with reference to the drawings.
FIG. 1 shows a cross section of the right half in the width direction of the pneumatic tire according to the first embodiment of the present invention. The tire 10 includes a pair of bead cores 1 and at least one layer (in the illustrated example, one layer) composed of a carcass ply that extends between the bead cores 1 in a toroidal shape and is folded around from the inner side to the outer side in the tire width direction. An inclined belt 3 comprising inclined belt layers 3a and 3b having a carcass 2 as a skeleton and a plurality of cords extending obliquely with respect to the tire equatorial plane CL and coated with rubber on the radially outer side of the crown portion of the carcass 2; The belt reinforcing layer 4 and the tread 6 on the radially outer side of the inclined belt 3 are sequentially provided.
Further, centering on the tire equatorial plane CL, the maximum width of the tire is indicated as SW, the belt width of the maximum width layer 3b of the inclined belt layer is indicated as BW, and the distance between the ground contact ends Te of the tread is indicated as TW (FIG. 1). Since it is a cross-sectional view of the right half of the tire 10 in the width direction, the distances shown in the figure are SW / 2, BW / 2, and Te / 2, respectively.
In FIG. 1, among the inclined belt layers 3 a and 3 b, the inclined belt layer 3 b located on the inner side in the tire radial direction has the maximum width, but the inclined belt layer 3 a located on the outer side in the tire radial direction has the maximum width. You may have.
Further, the tire according to the present invention is a circumferential belt comprising at least one circumferential belt layer in which a large number of cords extending along the tire circumferential direction are coated with rubber on the radially outer side of the inclined belt 3 of FIG. Can also be included.

In the tire 10, the maximum width layer 3 b of the inclined belt layer extends from the tread contact end Te to the outer side in the tire width direction and terminates at the end e. In this way, when at least one of the inclined belt layers 3a and 3b is extended to the outside in the tire width direction, an effect of improving the rigidity of the shoulder portion of the tire can be expected.
Specifically, particularly when the camber angle is applied, when the end e of the maximum width layer 3b of the inclined belt layer is positioned on the outer side in the tire width direction from the ground contact end Te of the tread, the bending of the inclined belt 3 caused by the load is caused. Therefore, shear strain on the outer side in the tire width direction due to the tire diameter difference can be suppressed.

In addition, it is important to dispose the dissimilar rubber layer Q having higher wear resistance than the tread rubber other than the region in the region of the tread surface layer indicated by the oblique line on the outer side in the tire width direction from the ground contact end Te.
Here, the dissimilar rubber layer Q is arranged between the ground contact Te of the tread 6 and the end e of the maximum width layer 3b of the inclined belt layer from the end e of the maximum width layer 3b of the inclined belt layer in the tire width direction. It is located in the area extending outside.

According to such a configuration, the time until the lateral groove wears and disappears is delayed compared to other regions, so that the wear of the shoulder portion is delayed. As a result, the wear life of the tire (the life until the tire reaches the end of wear) is reduced. Can be extended. In general, the position of the ground contact edge of the tread moves from the position of the ground contact edge Te of the new tire to the outside in the tire width direction as wear progresses on the tread surface. For this reason, if a tread region having high wear resistance is provided outside the ground contact end Te of the new tire in the tire width direction, the progress of wear on the tread surface is delayed in this region, that is, the tire width direction outside of the contact end Te. The amount of movement to can be reduced. In this manner, wear that proceeds on the tread surface on the outer side in the tire width direction from the ground contact end Te can be suppressed. In addition, by disposing different rubbers in the radial direction of the tread, shear strain on the tread surface becomes difficult to propagate, and there is an effect of suppressing wear on the tread surface.
Further, the different rubber layer Q has a property of high hardness and low wear rate, but has a large hysteresis loss and tends to increase the rolling resistance of the tire. However, in the arrangement of the present invention, the different rubber layer Q Does not hinder rolling resistance because it is not in the steady contact area.
Here, the ground contact Te is a contact end position in a new tire.

Next, Fig.2 (a) is sectional drawing from the side part to a shoulder part of the tire which concerns on 2nd Embodiment of this invention. The same components as those in FIG. 1 are denoted by the same reference numerals as those in FIG. In such a tire 10, the different rubber layer Q is formed between the ground end Te of the tread 6 and the end e of the maximum width layer 3 b of the inclined belt layer and the tire width from the end e of the maximum width layer 3 b of the inclined belt layer. It is arranged in the area to the outside in the direction.
Here, when the tire width direction distance from the tread grounding end Te to the maximum tire width position i is C, the end e of the maximum width layer 3b of the inclined belt layer is defined as C / It is preferable that the outer end of the different rubber layer Q in the tire width direction is disposed in the range of the contact end Te side C / 2 of the tread.

According to this configuration, it is possible to improve the uneven wear resistance of the tread while suppressing the rolling resistance of the tire. As described above, the rubber composition of the dissimilar rubber layer Q has a property of high hardness and low wear rate, but has a large hysteresis loss and tends to increase the rolling resistance of the tire. Therefore, by limiting the length of the different rubber layer Q in the tire width direction to an appropriate range according to the tire width direction distance C, in particular, the tread contact end of the different rubber layer Q increases as the travel distance increases. During traveling when moving to the region, the amount of heat generated in the different rubber layer Q can be suppressed to a certain amount or less, and the rolling resistance of the tire can be prevented from being extremely increased.
In addition, even if the amount of movement of the ground contact end position due to wear on the tread surface is taken into account, if the different rubber layer Q is in the above range, uneven wear of the tread can be sufficiently suppressed to extend the wear life of the tire. Is possible.

  Next, FIG.2 (b) is sectional drawing from the side part to a shoulder part of the tire which concerns on 3rd Embodiment of this invention. In such a tire 10, the different rubber layer Q is arranged in a range from the ground end Te of the tread 6 and the end e of the maximum width layer 3b of the inclined belt layer to the ground end Te side C / 2. Then, the thickness of the different rubber layer Q in the radial direction is 10% or more and 60% or less of the tread rubber cage at the end e of the maximum width layer 3b of the inclined belt layer from the tread surface toward the inner side in the tire radial direction. It is preferable to make it.

According to this configuration, it is possible to further improve the uneven wear resistance performance of the tread while reliably suppressing the rolling resistance of the tire. As described above, the rubber composition of the different rubber layer Q has a property of high hardness and low wear rate, but has a large hysteresis loss and tends to inhibit the rolling resistance performance of the tire. Therefore, by limiting the thickness of the different rubber layer Q and keeping the volume of the different rubber layer in an appropriate range, the amount of heat generated in the different rubber layer Q can be reduced compared to the tires of the first and second embodiments described above. This makes it possible to reduce hysteresis loss to a minimum.
In addition, if the thickness of the different rubber layer Q is limited to the above range and different rubber layers are arranged in a well-balanced manner on the tread surface, the shear strain on the tread surface is less likely to propagate and the wear on the tread surface is suppressed. The effect to do increases.

Examples of the present invention will be described below.
A conventional tire of size 245 / 40R18, a comparative tire, and an inventive tire were prototyped according to the following specifications. And after assembling each test tire to the applicable rim and filling the internal pressure 230 kPa, it was mounted on the vehicle and traveled on a dry circuit road surface to evaluate the wear resistance performance and the rolling resistance performance against the travel distance at the ground contact edge. . Rolling resistance performance refers to the ability to reduce rolling resistance.
Applicable rim is an industrial standard that is effective in the area where tires are produced and used. A standard rim.

Each of the test tires includes one carcass, two inclined belt layers, and one reinforcing belt.
The example tire 1 has the basic structure shown in FIG. 1 and includes a different rubber layer Q from the outer side in the tire width direction of the ground contact end Te of the tread 6 toward the direction.
In the tire 2 of the invention, the end e of the maximum width layer 3b of the inclined belt layer is located in a range of the ground contact end Te side C / 3 of the tread, and the outer end in the tire width direction of the different rubber layer Q is the contact end Te of the tread. It is the same as that of the invention example tire 1 except that it is located in the range of the side C / 2.
The tire 3 of the invention is such that the end e of the maximum width layer 3b of the inclined belt layer is located in a range of the tread contact end Te side C / 3, and the outer end in the tire width direction of the different rubber layer Q is the tread contact. The tread rubber at the end e of the maximum width layer 3b of the inclined belt layer is located in the range of the end Te side C / 2, and the radial thickness of the different rubber layer Q is from the tread surface toward the inside in the tire radial direction. Except for 30% of the cage, it is the same as the tire 1 of the invention.
The conventional example tire is the same as the example tire 1 except that the different type rubber layer Q is not provided.
The comparative tire 1 is the same as the inventive tire 1 except that the dissimilar rubber layer Q extends beyond the contact end Te of the tread 6 to the inner side in the tire width direction.
In the comparative example tire 2, the inner end of the different rubber layer Q is located on the inner side in the tire width direction from the contact end Te of the tread 6, and the outer end is positioned in a range of the contact end Te side C / 2 of the tread. It is the same as the tire 1 of the invention.
In the comparative example tire 3, the inner end of the dissimilar rubber layer Q is located on the inner side in the tire width direction from the contact end Te of the tread 6, and the outer end is located in the range of the contact end Te side C / 2 of the tread. The thickness of Q in the radial direction is the same as that of the inventive example tire 1 except that the thickness in the radial direction of the tread is 30% of the tread rubber cage at the end e of the maximum width layer 3b of the inclined belt layer from the tread surface toward the inner side in the tire radial direction. is there.

(Uneven wear resistance)
FIG. 3 is a graph showing the relationship between the travel distance and the wear amount at the ground contact Te until the wear reaches the groove depth of the ground contact Te.
In the figure, the gentle slope of the line indicates that the wear is slowly progressing, and the longer the travel distance until the wear life of the tire (the groove depth of the ground contact Te) is, the more uneven the resistance is. It means that the wear performance is excellent.

(Rolling resistance performance)
FIG. 4 is a graph showing the balance between the wear life and rolling resistance performance at the ground contact Te of each test tire. Here, the performance evaluation is lower for the wear life and the rolling resistance performance as it goes to the upper left of the graph, and the performance is higher for both performances as it goes to the lower right of the graph.

  1: bead core 2: carcass 3: inclined belt 3a: inclined belt layer 3b: maximum width layer of inclined belt layer 4: belt reinforcing layer 6: tread 10: pneumatic tire e: belt end i: maximum tire width position Te: ground contact End Q: Different rubber layer C: Distance between ground contact Te and maximum tire width position i CL: Tire equatorial plane SW: Tire width BW: Belt width TW: Tread width (distance between ground ends)

Claims (3)

With at least one layer of carcass straddling a toroidal shape between a pair of bead portions, a large number of cords extending obliquely with respect to the tire equatorial plane are coated with rubber on the radially outer side of the crown portion of the carcass. A pneumatic tire in which at least one inclined belt layer and a tread are disposed,
At least one layer of the inclined belt layer extends from the ground contact end of the tread to the outside in the tire width direction,
On the surface of the tread, the width of the tire from the widthwise end of the maximum width layer of the inclined belt layer is between the ground contact end of the tread and the position corresponding to the width direction end of the maximum width layer of the inclined belt layer. A pneumatic tire characterized in that a dissimilar rubber layer having higher wear resistance than a tread rubber other than the region is disposed in a region up to the outer side in the direction.   The end of the maximum width layer of the inclined belt layer is in a range from the contact end of the tread to the maximum width position of the tire in the range from C / 3 to the contact end side C / 3 of the tread, where C is the tire width direction distance. 2. The pneumatic tire according to claim 1, wherein an outer end in the tire width direction of the dissimilar rubber layer is located in a range up to a contact end side C / 2 of the tread.   The thickness of the different rubber layer in the tire radial direction is in the range of 10% to 60% of the tread rubber gauge at the end of the maximum width layer of the inclined belt layer from the tread surface toward the inner side in the tire radial direction. The pneumatic tire according to claim 1, wherein the pneumatic tire is provided.

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