JP2011168206A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of making both compatible a reduction in rolling resistance of the tire and an improvement in braking performance of the tire. <P>SOLUTION: This pneumatic radial tire includes a pair of bead parts 1, a sidewall part 2 respectively extending outside in the tire radial direction from the bead parts 1, a tread part 3 continuing with the outside end in the respective tire radial directions of the sidewall part 2, a carcass layer 4 arranged between the pair of bead parts 1 and a belt layer 5 composed of at least two belt plies 5a and 5b arranged on the outer peripheral side of the tread part 3 of the carcass layer 4, and is provided with a first belt reinforcing layer 6a narrower in a width than the belt ply 5b arranged on the outermost peripheral side and arranged on the outer peripheral side of the belt layer 5 so as not to overlap with the outside end 5bEout in the tire width direction of the belt ply 5b arranged on the outermost peripheral side, and a second belt reinforcing layer 6b arranged on the inner peripheral side of the belt layer 5 so as to overlap with the outside end 5aEout in the tire width direction of the belt ply 5a arranged on the innermost peripheral side. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is arranged between a pair of bead portions, a sidewall portion extending outward in the tire radial direction from the bead portion, a tread portion connected to each outer end in the tire radial direction of the sidewall portion, and the pair of bead portions. The present invention relates to a pneumatic radial tire including a carcass layer and a belt layer including at least two belt plies arranged on the outer periphery side of a tread portion of the carcass layer.

  In recent years, with the growing awareness of global environmental protection, many efforts are being made to improve the fuel efficiency of vehicles to conserve resources. With regard to pneumatic tires, since the rolling resistance of tires has a great influence on the fuel efficiency of vehicles, research and development for reducing rolling resistance is being carried out. Conventionally, as a method for reducing rolling resistance, for example, a method of using rubber having a small hysteresis loss while considering wear resistance or the like in a tread portion having a high energy contribution during tire traveling, or a small hysteresis loss. A method of embedding rubber in a base rubber layer of a tread portion has been performed.

  Although the rolling resistance of tires has been considerably improved by improving the rubber material of the tread part, further reduction in rolling resistance is required for tires in response to the recent rise in fuel and resource consciousness. . However, if the rolling resistance is further reduced by improving the rubber material of the tread portion, there is a possibility that the wear resistance and running performance will be adversely affected. For this reason, it is necessary not only to improve the rubber material of the tread portion but also to devise the structure of the tire.

  Patent Document 1 below describes a pneumatic tire in which a belt reinforcing layer is disposed on the outer peripheral side of the belt layer so as to cover the entire belt layer. Such pneumatic tires have the problem of reducing rolling resistance and road noise, but with a configuration in which a belt reinforcement layer is arranged to cover the entire belt layer, road noise can be reduced, but rolling resistance is reduced. The effect is not satisfactory.

  On the other hand, Patent Documents 2 and 3 below describe a pneumatic tire in which a belt reinforcing layer is disposed between the outer end of the belt layer in the tire width direction and the carcass layer. According to these configurations, deformation of the end portion in the tire width direction of the belt layer can be suppressed and puncture resistance performance can be improved, but rolling resistance cannot be reduced.

  Further, in Patent Document 4 below, a belt reinforcing layer disposed on the outer peripheral side of the belt layer so as to cover the entire belt layer, and only the end portion in the tire width direction of the belt layer between the belt layer and the carcass layer. A pneumatic tire comprising an overlapping narrow belt reinforcing layer is described. However, such a pneumatic tire is intended to improve the durability by suppressing the separation between the belt layer and the carcass layer, and cannot reduce the rolling resistance.

  As described above, reducing the rolling resistance by devising the structural surface of the tire has room for further improvement in the prior art. Further, reducing rolling resistance generally tends to lead to a reduction in tire braking performance. This tendency is particularly remarkable when the rolling resistance is reduced by improving the rubber material of the tread portion. Therefore, there is a trade-off between reducing the rolling resistance of the tire and improving the braking performance of the tire, and it has been difficult to achieve both.

JP 2009-184562 A JP 7-323703 A JP 2006-335159 A JP 2007-137172 A

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a pneumatic tire that achieves both reduction in rolling resistance of the tire and improvement in braking performance of the tire.

  As described in Patent Document 4, when the belt reinforcing layer is disposed on the outer peripheral side of the belt layer, in order to prevent separation at the outer end in the tire width direction of the belt layer and improve durability, the entire belt layer is It is common sense to arrange a belt reinforcing layer to cover. However, the present inventor, contrary to such common sense, in the configuration in which the belt layer is sandwiched between the inner circumferential side and the outer circumferential side by the belt reinforcing layer, the outer circumferential side of the belt ply constituting the belt layer does not overlap with the outer end in the tire width direction. The belt-reinforcement layer of the belt and the belt-reinforcement layer on the inner peripheral side so as to overlap the outer edge in the tire width direction of the belt ply constituting the belt layer reduce the rolling resistance of the tire and It was found that the braking performance can be improved. The present invention has been made as a result of the above-described studies, and achieves the above-described object with the following configuration.

  That is, the pneumatic tire according to the present invention includes a pair of bead portions, sidewall portions extending outward in the tire radial direction from the bead portions, and tread portions continuous to the respective tire radial outer ends of the sidewall portions. A pneumatic radial tire comprising a carcass layer disposed between the pair of bead portions and a belt layer including at least two belt plies disposed on an outer peripheral side of the tread portion of the carcass layer. The first belt reinforcement disposed on the outer peripheral side of the belt layer so as to be narrower than the belt ply disposed on the outer periphery and not to overlap the outer end in the tire width direction of the belt ply disposed on the outermost peripheral side. And a second belt reinforcing layer disposed on the inner peripheral side of the belt layer so as to overlap an outer end in the tire width direction of the belt ply disposed on the innermost peripheral side. The features.

  In the above pneumatic tire, the first belt reinforcement layer reinforces the center area of the tread portion. Therefore, the center area is set during steady speed running on an expressway, that is, when the load on the tire is low. Shear deformation in the tire circumferential direction can be suppressed at the center. Furthermore, by reinforcing around the center area, the grounding performance of the shoulder area is enhanced, and the in-plane contraction force on the tire contact surface (the force acting toward the center within the contact surface when the tire is grounded) ) Can be suppressed. As a result, the rolling resistance at the time of low load can be reduced.

  The effect of reducing the rolling resistance at the time of low load described above is that the first belt reinforcing layer is narrower than the belt ply disposed on the outermost peripheral side and the tire ply direction of the belt ply disposed on the outermost peripheral side. This is achieved by being arranged on the outer peripheral side of the belt layer so as not to overlap the outer end. On the other hand, as is apparent from the evaluation test results described later, when the first belt reinforcing layer is configured to cover the entire belt ply disposed on the outermost peripheral side, the rolling resistance can be reduced when the load is low. Do not play. This is because if the first belt reinforcement layer is configured to cover the entire belt ply disposed on the outermost peripheral side, the rigidity of the shoulder portion is excessively increased, and the grounding property of the shoulder portion is adversely affected. It is estimated that.

  Also, when the vehicle is braked, that is, when the load on the tire is high, the belt ply disposed between the belt layer and the carcass layer and on the innermost circumferential side overlaps with the outer end in the tire width direction. The rigidity of the belt layer end portion is increased by the second belt reinforcing layer. As a result, the ground contact surface shape of the tire under high load becomes vertically long in the tire circumferential direction in the center region, and the rolling resistance increases conversely under high load (during braking). As a result, the braking performance of the tire is improved.

  In the pneumatic tire, it is preferable that the first belt reinforcing layer and the second belt reinforcing layer do not overlap in the tire width direction. According to such a configuration, it is possible to further reduce rolling resistance by suppressing an increase in the total weight of the belt reinforcing layer.

  In the pneumatic tire, it is preferable that an inclination angle of the reinforcing element of the first belt reinforcing layer and the reinforcing element of the second belt reinforcing layer with respect to the tire equatorial plane is −10 to 10 °. According to this configuration, the first belt reinforcing layer can suppress the movement of the tread portion in the center region, and can effectively suppress the shear deformation. Further, in the present invention, the second belt reinforcing layer is arranged so as to circumscribe the carcass layer. In this case, by bringing the reinforcing element of the second belt reinforcing layer closer to the tire circumferential direction, Stiffness can be effectively increased. As a result, it is possible to more effectively achieve both reduction in tire rolling resistance and improvement in tire braking performance.

  In the pneumatic tire, an outer end in the tire width direction of the first belt reinforcing layer is formed 5 mm or more inside an outer end in the tire width direction of the belt ply disposed on the outermost peripheral side, and is formed in the tread portion. It is preferable that the outermost main groove on the outermost side in the tire width direction is disposed outside the center of the groove width. Further, in the pneumatic tire, a tire width direction interval between a tire width direction inner end of the second belt reinforcing layer and a tire ply outer end of the belt ply disposed on the outermost peripheral side is 5 to 10 mm. It is preferable that Further, in the pneumatic tire, a tire width direction interval between a tire width direction outer end of the second belt reinforcing layer and a tire width direction outer end of the belt ply disposed on the innermost peripheral side is 2 to 2. 10 mm is preferable. According to these configurations, the rolling resistance of the tire can be further effectively reduced.

The tire meridian half sectional view showing an example of a pneumatic tire according to the present invention The elements on larger scale of the tire meridian half section which shows an example of the pneumatic tire concerning the present invention

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a half sectional view of a tire meridian showing an example of a pneumatic tire according to the present invention. In FIG. 1, WD indicates the tire width direction. Since the pneumatic tire of this embodiment is symmetrical with respect to the equator plane C, the left half is omitted in FIG.

  A pneumatic tire shown in FIG. 1 includes a pair of bead portions 1, a sidewall portion 2 that extends outward in the tire radial direction from each bead portion 1, and a tread portion 3 that is continuous with each tire radial direction outer end of the sidewall portion 2. A carcass layer 4 disposed between the pair of bead portions 1, and a belt layer 5 including two belt plies 5 a and 5 b disposed on the outer peripheral side of the tread portion 3 of the carcass layer 4. The bead portion 1 is provided with an annular bead 1a formed by rubber covering a convergent body such as a steel wire and a bead filler 1b made of hard rubber.

  The carcass layer 4 is composed of at least one (two in the present embodiment) carcass ply and is arranged so as to be bridged between the bead portions 1. The carcass ply is formed by rubber covering a cord extending at an angle of approximately 90 ° with respect to the tire equatorial plane C, and is locked in a state where its end is wound up via a bead 1a. As the carcass ply, those formed by coating an organic fiber cord such as polyester, rayon, nylon, or aramid with rubber are preferably used.

  A belt layer 5 is disposed on the outer peripheral side of the tread portion 3 of the carcass layer 4, and in this embodiment, a belt ply 5a in which the belt layer 5 is disposed on the innermost peripheral side, and a belt ply 5b disposed on the outermost peripheral side, It consists of The carcass layer 4 is reinforced by the effect of the belt plies 5a and 5b. The belt plies 5a and 5b are formed by rubber covering reinforcing elements extending at an angle of 19 to 30 ° with respect to the tire equatorial plane C. The reinforcing elements are opposite to each other between the belt plies 5a and 5b. Arranged to intersect. The cord material is exemplified by steel, and the strength range is exemplified by 315 to 433 kN / m. In this embodiment, an example of the belt layer 5 composed of two belt plies is shown, but in the present invention, a third belt ply may be disposed between the belt plies 5a and 5b.

  In the tread portion 3, main grooves 31 and 32 extending in the tire circumferential direction are formed, and a land portion 33 partitioned by these is formed. The land portion 33 may be a rib, or may be a block defined by main grooves 31 and 32 and a lateral groove (not shown) extending in the tire width direction. Further, the arrangement and dimensions of the main grooves 31 and 32 are not particularly limited, but for the outermost main groove 32 in the tire width direction, the distance from the tire equator C to the groove width center is 35 to 50 mm, and The groove width is preferably 5 to 7 mm.

  The pneumatic tire shown in FIG. 1 is narrower than the belt ply 5b disposed on the outermost peripheral side and does not overlap with the outer end 5bEout in the tire width direction of the belt ply 5b disposed on the outermost peripheral side. The first belt reinforcement layer 6a disposed on the outer peripheral side of the layer 5 and the inner peripheral side of the belt layer 5 so as to overlap the outer end 5aEout in the tire width direction of the belt ply 5a disposed on the innermost peripheral side. A second belt reinforcing layer 6b. In the present embodiment, in particular, the first belt reinforcing layer 6a is disposed immediately above the belt layer 5 (immediately above the belt ply 5b), and further directly above the carcass layer 4 and directly below the belt layer 5 (belt ply 5a). The second belt reinforcing layer 6b is arranged directly below.

  The first belt reinforcing layer 6a exhibits the effect of suppressing shear deformation in the center region of the tread portion 3 at the time of low load, the effect of improving the ground contact property of the shoulder region, and suppressing the in-plane contraction force. Thereby, the rolling resistance of the tire at the time of low load can be reduced.

  As shown in FIG. 1, the first belt reinforcing layer 6 a has a tire width direction outer end 6 a Eout that is 5 mm or more inside (Z ≧ 5 mm) from the tire width direction outer end 5 b Eout of the belt ply 5 b and is formed in the tread portion 3. It is preferable that the outermost main groove 32 on the outermost side in the tire width direction is set to be arranged on the outer side than the groove width center 32C. With this setting, the rolling resistance of the tire can be further effectively reduced.

  The reinforcing element of the first belt reinforcing layer 6a is preferably made of a light high modulus fiber such as organic fiber or carbon fiber as a raw material. Examples of usable organic fibers include nylon, polyethylene terephthalate (PET), aramid fiber, polyethylene naphthalate (PEN), and aliphatic polyketone fiber (POK). The strength range of this reinforcing element is preferably 79 to 276 kN / m, and considering this point, it is preferable to use nylon as a raw material for the reinforcing element.

  The reinforcing element of the first belt reinforcing layer 6a has an inclination angle with respect to the tire equatorial plane C of preferably −10 to 10 °, more preferably −5 to 5 °, and substantially parallel to the tire equatorial plane C. It is particularly preferred that it is (approximately 0 °). As the inclination angle of the reinforcing element of the first belt reinforcing layer 6a with respect to the tire equatorial plane C approaches 0 °, the first belt reinforcing layer suppresses the movement in the center region of the tread portion, and effectively reduces the shear deformation. Can be suppressed.

  The 2nd belt reinforcement layer 6b exhibits the effect which raises the rigidity of the belt layer 5 edge part. Thereby, rolling resistance increases at the time of high load (during braking), and as a result, the braking performance of the tire is improved.

  The second belt reinforcing layer 6b is disposed on the inner peripheral side of the belt layer 5 so as to overlap the tire width direction outer end 5aEout, but the width in the tire width direction is narrower than that of the first belt reinforcing layer 6a. is there. The second belt reinforcing layer 6b can further improve the rolling resistance of the tire by setting the tire width direction interval X between the inner end 6bEin in the tire width direction and the outer end 5bEout in the tire width direction of the belt ply 5b to 5 to 10 mm. Can be reduced. On the other hand, if X exceeds 10 mm, the effect of improving the braking performance may not be sufficient. The second belt reinforcing layer 6b has a tire rolling resistance when the tire width direction interval Y between the tire width direction outer end 6bEout and the tire width direction outer end 5aEout of the belt ply 5a is set to 2 to 10 mm. Furthermore, it can reduce effectively. On the other hand, if Y is less than 2 mm, the effect of improving braking performance may not be sufficient, and if Y exceeds 10 mm, the effect of reducing rolling resistance at low loads may not be sufficient.

  The reinforcing element of the second belt reinforcing layer 6b is preferably made of a light high modulus fiber such as an organic fiber or carbon fiber as a raw material, like the first belt reinforcing layer 6a. Usable organic fibers are the same as those of the first belt reinforcing layer 6a, and those using nylon as a raw material are particularly preferable. Further, the reinforcing element of the second belt reinforcing layer 6b has an inclination angle with respect to the tire equatorial plane C of preferably −10 to 10 °, more preferably −5 to 5 °. It is particularly preferable that they are substantially parallel (approximately 0 °). As the inclination angle of the reinforcing element of the second belt reinforcing layer 6b with respect to the tire equatorial plane C approaches 0 °, the rigidity of the belt layer end can be effectively increased.

  As shown in FIG. 1, in the present embodiment, the first belt reinforcing layer 6a and the second belt reinforcing layer 6b are arranged so as not to overlap in the tire width direction. According to this configuration, it is possible to further reduce rolling resistance by suppressing an increase in the total weight of the belt reinforcing layers 6a and 6b.

  The pneumatic tire of the present invention is the same as a normal pneumatic tire except that the belt reinforcing layers 6a and 6b are configured as described above, and any of the conventionally known materials, shapes, structures, manufacturing methods, etc. Can be adopted.

[Other Embodiments]
In the above-described embodiment, an example in which the carcass layer 4, the second belt reinforcing layer 6b, the belt layer 5 (belt ply 5a, belt ply 5b), and the first belt reinforcing layer 6a are stacked in order from the inner side in the tire radial direction is shown. It was. However, in the present invention, as shown in FIG. 2, the second belt reinforcing layer 6b may be folded inward via the tire width direction outer end 5aEout of the belt ply 5a. According to such a configuration, the rigidity of the end portion of the belt layer can be further increased, so that the rolling resistance is particularly increased at high loads. As a result, the braking performance of the tire is further improved.

  Examples that specifically show the structure and effects of the present invention will be described below. In addition, each performance evaluation of the tire was performed as follows.

(1) Rolling resistance under low load (during steady speed running) Using the tire according to the present invention (tire size: 195 / 65R15 91S, rim size: 15 × 6J), the rolling resistance measured in the drum running test is an index. evaluated. The case of the comparative example 1 is set to 100, and it shows that rolling resistance is so small that an index | exponent is small. The running conditions were as follows: drum diameter = 1.7 m, camber angle = 0 °, air pressure = 230 kPa, speed = 80 km / h, load = 4.5 kN.

(2) Rolling resistance under high load (during braking) The tire according to the present invention (tire size: 195 / 65R15 91S, rim size: 15 × 6J) was used, and the rolling resistance measured in the drum running test was evaluated as an index. . The case of Comparative Example 1 is set to 100, and the larger the index, the greater the rolling resistance and the better the braking performance. The running conditions were as follows: drum diameter = 1.7 m, camber angle = 0 °, air pressure = 230 kPa, speed = 80 km / h, load = 6.5 kN.

Examples 1-4
The pneumatic tire shown in FIG. 1, the inner end 6bEin in the tire width direction of the second belt reinforcing layer 6b, the outer end 5bEout in the tire width direction of the belt ply 5b and the interval X, and the outer side in the tire width direction of the second belt reinforcing layer 6b. Table 1 shows a distance Y between the end 6bEout and the outer end 5aEout in the tire width direction of the belt ply 5a, and an interval Z between the outer end 6aEout in the tire width direction of the first belt reinforcing layer 6a and the outer end 5bEoutZ in the tire width direction of the belt ply 5b. A pneumatic tire was manufactured in which both the inclination angle of the reinforcing element of the first belt reinforcing layer 6a and the reinforcing element of the second belt reinforcing layer 6b with respect to the tire equatorial plane were set to 0 °. The results are shown in Table 1.

Comparative Example 1
Implemented except that instead of the first belt reinforcing layer 6a, only a belt reinforcing layer configured to cover the entire belt layer 5 is provided and no belt reinforcing layer is provided between the carcass layer 4 and the belt layer 5. A pneumatic tire having the same configuration as in Example 1 was manufactured (set values of X, Y, and Z are shown in Table 1). The results are shown in Table 1.

Comparative Example 2
A pneumatic structure having the same configuration as that of the first embodiment except that a belt reinforcement layer configured to cover the entire belt layer 5 and a second belt reinforcement layer 6b are provided instead of the first belt reinforcement layer 6a. A tire was manufactured (set values of X, Y, and Z are shown in Table 1). The results are shown in Table 1.

Comparative Example 3
A pneumatic tire having the same configuration as that of Example 1 was manufactured except that the second belt reinforcing layer 6b was disposed on the outer peripheral side of the belt layer 5 (setting values of X, Y, and Z are shown in Table 1). The results are shown in Table 1.

  From the results of Table 1, in the pneumatic tires of Examples 1 to 4, the rolling resistance at low load is reduced and the rolling resistance at high load is increased, so that the rolling resistance is reduced and the braking performance is improved. It can be seen that both are compatible. On the other hand, in the pneumatic tire of Comparative Example 2 in which the first belt reinforcing layer 6a is changed to a belt reinforcing layer configured to cover the entire belt layer 5, the rolling resistance at low load is increased. It can be seen that the rolling resistance reduction effect cannot be obtained. Further, in the pneumatic tire of Comparative Example 3 in which the second belt reinforcing layer 6b is arranged on the outer peripheral side of the belt layer 5, the rigidity of the belt layer end portion is not sufficiently increased, so that the rolling resistance at high load does not increase. . As a result, it can be seen that the effect of improving the braking performance cannot be obtained.

1: Bead part 2: Side wall part 3: Tread part 4: Carcass layer 5: Belt layer 5a, 5b: Belt ply 6a, 6b: Belt reinforcing layer

Claims (6)

A pair of bead portions, a sidewall portion that extends outward in the tire radial direction from each of the bead portions, a tread portion that is connected to an outer end in the tire radial direction of each of the sidewall portions, and the pair of bead portions. A pneumatic radial tire comprising: a carcass layer; and a belt layer comprising at least two belt plies arranged on the outer periphery side of the tread portion of the carcass layer.
The belt ply disposed on the outer circumferential side of the belt layer is narrower than the belt ply disposed on the outermost circumferential side and does not overlap the outer end in the tire width direction of the belt ply disposed on the outermost circumferential side. 1 belt reinforcement layer, and the 2nd belt reinforcement layer distribute | arranged to the inner peripheral side of the said belt layer so that it may overlap with the tire width direction outer side end of the said belt ply distribute | arranged to the innermost periphery side, It is characterized by the above-mentioned. And pneumatic tires.   The pneumatic tire according to claim 1, wherein the first belt reinforcing layer and the second belt reinforcing layer do not overlap in the tire width direction.   The pneumatic tire according to claim 1 or 2, wherein an inclination angle of the reinforcing element of the first belt reinforcing layer and the reinforcing element of the second belt reinforcing layer with respect to the tire equatorial plane is -10 to 10 °.   The outer end in the tire width direction of the first belt reinforcing layer is at least 5 mm inside the outer end in the tire width direction of the belt ply disposed on the outermost peripheral side, and the outermost end in the tire width direction formed in the tread portion. The pneumatic tire according to any one of claims 1 to 3, wherein the pneumatic tire is disposed outside the center of the groove width of the main groove.   The distance in the tire width direction between the inner end in the tire width direction of the second belt reinforcing layer and the outer end in the tire width direction of the belt ply disposed on the outermost peripheral side is 5 to 10 mm. The pneumatic tire according to any one of the above.   The distance in the tire width direction between the outer end in the tire width direction of the second belt reinforcing layer and the outer end in the tire width direction of the belt ply disposed on the innermost circumferential side is 2 to 10 mm. The pneumatic tire according to any one of the above.

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