JP4770469B2 - Pneumatic tires for passenger cars - Google Patents

Description

  The present invention relates to a pneumatic tire for a passenger car having good tipping prevention and steering stability.

  In general, in order to improve the overturning limit performance in a tire for a passenger car, tire characteristics that reduce the cornering force at a high slip angle are required.

  That is, in order to ensure the capsize limit performance, tire characteristics are required so that the lateral force at the time of a high slip angle or a high load becomes small.

  As a measure to reduce the lateral force at the time of such a high slip angle or high load, conventional methods include increasing the belt angle, decreasing the tread rubber grip force, increasing the groove area, or increasing the casing rigidity. Although these methods can be reduced, these methods are factors that reduce steering stability, braking performance, and wear resistance, and thus it is difficult to achieve both the rollover limit performance.

  The pneumatic tire for passenger cars of the present invention is to realize a tire that achieves both good fall prevention and steering stability, and the basic technical concept thereof will be described later. The object is to reduce the number of cord ends near the portion (reduce the number density of cords) and reduce the stiffness near the end portion.

  Here, what is described below is known as a tire in which the number of cord ends is smaller than the central portion of the belt.

  For example, a reinforcing layer is provided between the carcass and the carcass and the tread, and the reinforcing layer includes at least two cords intersecting each other. In the radial cross section of the reinforcing layer, (radius of the reinforcing layer end) / (crown center) (Reinforcing layer radius) In a tire having a value of <0.95, at least one of the reinforcing layers has a non-uniform cord width, and the number of cords driven at the end of the layer is equal to the number of driving at the crown center or Proposals have been made for a small number of pneumatic tires (Patent Document 1).

  However, the pneumatic tire described in Patent Document 1 is originally used for motorcycle (two-wheel) radial tires and aircrafts in which the radius of the reinforcing layer end is smaller than the radius of the reinforcing layer at the crown center. In radial tires or radial tires for construction vehicles, the number of cords to be driven increases at the end, and therefore, the number of cords in the center portion is increased and secured while preventing separation at the end of the reinforcing layer. This is based on the technical idea, and did not realize good fall prevention and steering stability in pneumatic tires for passenger cars.

  In addition, for the purpose of providing a heavy-duty pneumatic radial tire with improved both wander resistance and durability, the first belt layer has a plurality of belt layers and is close to the carcass layer. A heavy-duty pneumatic radial tire has been proposed in which the cord density in the central region in the tire width direction is larger than the cord density in both end regions in the tire width direction (Patent Document 2).

However, the pneumatic tire described in Patent Document 2 is used to increase exclusively the cord density in the center region in the tire width direction in the heavy-duty pneumatic radial tire. The cord density in the central region of the tire is made larger than the cord density in both end regions by configuring the belt layer excluding 3/1 to 1/4 of the above, and good for pneumatic tires for passenger cars It was not something that realized the proper fall prevention and handling stability.
JP 61-37501 A Japanese Patent Laid-Open No. 9-2016

  In view of the above-described points, an object of the present invention is to provide a pneumatic tire that achieves both good fall prevention performance and steering stability in the field of pneumatic tires for passenger cars.

  The pneumatic tire for passenger cars of the present invention that achieves the above-described object has the following configuration.

  That is, in a pneumatic tire in which at least two plies of a belt ply formed by inclining a steel cord with respect to the tire equator line are arranged on the outer side in the tire radial direction of a carcass ply formed by radially arranging carcass cords. In the region E having a width 0.05 times the belt ply width W1 from the endmost part of the belt ply to the tire inward direction, the protruding width W2 of the steel cord terminal to the region E is different in the tire circumferential direction. The ratio R of the number n in which the protruding width W2 of the steel cord terminal to the region E with respect to the number N of steel cords inside the tire from the region E is 75% or less of the region width (= n / N ) Is a pneumatic tire for passenger cars having a value of 0.5 to 0.85.

  According to the present invention, the rigidity of the belt ply end portion can be appropriately reduced, so that it is possible to provide a pneumatic tire for a passenger car that achieves both good fall prevention performance and steering stability. It is possible to provide a pneumatic tire for a passenger car with improved rollover limit performance without sacrificing stability, braking performance, and wear resistance.

  The present invention has been made by paying attention to the fact that the tire contacts the ground outside the normal running when performing a rollover limit performance test (double lane change test, fish hook test, etc.). According to the pneumatic tires for passenger cars, it greatly contributes to the improvement of steering stability and wear resistance, and the belt rigidity at the ground contact edge of the shoulder can be intentionally lowered while maintaining the performance during normal driving. As a result, it is possible to reduce the cornering force at high slip angles by suppressing an increase in the contact area of the shoulder that is heavily loaded at high slip angles, and to improve steering stability, braking performance, and wear resistance. The capsizing limit performance can be improved without sacrificing.

Hereinafter, the pneumatic tire for passenger cars of the present invention will be described in more detail.
In the pneumatic tire for a passenger car of the present invention, at least two plies are formed on a belt ply formed by inclining a steel cord with respect to the tire equator line on the outer side in the tire radial direction of a carcass ply formed by radially arranging carcass cords. In the arranged pneumatic tire, the steel cord terminal protrudes into the region E in the region E having a width 0.05 times the belt ply width W1 from the outermost end portion of at least one belt ply toward the inner side of the tire. The width W2 is mixed along the tire circumferential direction so that the number N of steel cords inside the tire relative to the region E (the number N of steel cords) is the protrusion width W2 of the steel cord terminal to the region E A ratio R (= n / N) of the number n (lines) which is 75% or less of the width of E is 0.5 to 0.85.

  Such a pneumatic tire for a passenger car according to the present invention will be described with reference to FIGS. 1, 2 and 3. FIG. 1 is a partial sectional view in the tire meridian direction for explaining the pneumatic tire according to the present invention. FIG. 3 is a partial cross-sectional schematic model diagram, particularly focusing on a belt portion.

  2 (a), 2 (b), and 2 (c) illustrate the pneumatic tire of the present invention, and the belt ply width extends from the outermost end (outermost side) of at least one belt ply toward the inside of the tire. Schematic depicting a model of a state where the steel cord ends are mixed along the tire circumferential direction so that the protruding width W2 of the steel cord terminal into the region E is different in the region E having a width 0.05 times W1. It is a top view.

  In the present invention, the protruding width W2 of the steel cord terminal to the area E is the inside of the area E from the end of the belt ply (0.05 × W1) as shown in the model in FIG. The length from which the steel cord protrudes in the width direction to the extreme end side.

  In FIG. 1, a pneumatic tire 1 for a passenger car according to the present invention includes a tread 2 and a carcass 3, and a carcass 3 portion includes a carcass ply 4 in which carcass cords are radially arranged, and a tire radial direction of the carcass ply 4. A plurality of cords arranged on the outer side have an inclination angle θ (for example, 15 ° to 33 °) with respect to the tire equator line and pass through the tire equator line position toward the tire axial end side. It is composed of at least two belt plies 5 and 6 which are linearly arranged in parallel with each other and covered with rubber.

  The belt ply 5 in the inner layer is a so-called first belt, and the belt ply 6 on the outer side is a so-called second belt. 7 and 8 are belt cover layers not directly related to the gist of the present invention. L indicates the tire equator line, and W1 indicates the belt ply width.

  The pneumatic tire for passenger cars of the present invention has a width that is 0.05 times the belt ply width W1 from the end of at least one belt ply toward the inside of the tire, as shown in FIGS. In the region E, the steel cord terminals are mixed along the tire circumferential direction so that the protruding width W2 to the region E is different.

  As shown in the model in FIG. 3, the degree of the mixture is a belt cord 9 having a protruding width W2 of 100% of the width of the region E, a belt cord 10 having a protruding width W2 of 0% of the width of the region E, Belt cord 12 having a protruding width W2 of 35% of the width of region E, belt cord 13 having a protruding width W2 of 0% of the width of region E, or belt having a protruding width W2 of 65% of the width of region E It is important that the cords 14 and the like are mixed. Specifically, the protrusion width W2 of the steel cord terminal to the region E with respect to the number N of steel cords inside the tire from the region E is 75% or less of the region width ( It is important that the ratio R (= n / N) of the number n is 0.5 to 0.85.

  According to the present invention, by satisfying the relationship, the rigidity of the belt ply end can be appropriately reduced, and a pneumatic tire for a passenger car that achieves both good fall prevention and steering stability can be realized. .

Particularly preferably, the ratio R (= n / N) is in the range of 0.50 to 0.7.
Further, a steel cord having a protruding width W2 to the region E of the steel cord terminal of 75% or less of the region width and a steel cord having the protruding width W2 larger than 75% of the region width and within 100% are: It is preferable that they are alternately arranged one by one. Alternatively, it is also preferable that the same number of plural pieces are alternately arranged, or one of them is one or plural and the other is different from the one plural. It is also preferable that the plurality are arranged alternately, and the arrangement is not particularly limited. FIG. 5A shows an example of arrangement for every two or three lines, and FIG. 5B shows an example of every two lines.

  Here, R is R = n / N, and the steel cord end protrusion width W2 to the region E with respect to the number N of steel cords inside the tire from the region E is 75% or less of the region width. This is a value defined by the ratio R (= n / N) of the number n of cords, and is calculated based on the respective measured numerical values over the entire circumference of the tire.

  The value of R is a value obtained for the single belt ply, and is calculated within a single belt ply in which cord ends are mixed and cords are arranged.

  Therefore, in the case where both or only one of the two belt plies has a steel cord with mixed cord ends, the driving cords for the two belt plies are considered as a denominator Instead, each is considered within a single belt ply. The point is that it is a problem whether or not the belt ply having low rigidity at the end portion is used as a single unit.

  (A), (b), (c), and (d) of FIG. 4 are schematic plan views depicting the arrangement of steel cords as a schematic model for explaining pneumatic tires other than the present invention. (A) A mixed state does not exist, (b) a cord arrangement angle is changed in the middle, and (c) a cord arrangement angle is waved in the middle. The one in which the end portion of the belt ply is cut into a sawtooth shape as shown in (d) so that the cord does not exist with the belt ply is not included in the present invention.

  The present invention pays attention to the fact that tires touch the outside of normal running when performing rollover limit performance tests (double lane change test, fish hook test, etc.), steering stability and wear resistance By increasing the belt rigidity at the ground contact edge of the shoulder part intentionally while maintaining the performance during normal driving, it is possible to increase the ground contact area of the shoulder part that is heavily loaded at high slip angles. It is possible to suppress the cornering force at a high slip angle, and to improve the rollover limit performance without sacrificing the steering stability, braking performance, and wear resistance.

Examples 1-3, Comparative Examples 1-3
The belt ply in which the steel cords are arranged in a staggered manner is used on the inner layer side of the two belt plies so as to be in a mixed state in which one cord is alternated, similar to the model diagram shown in FIG. A pneumatic tire for passenger cars according to the present invention having a tire size of 265 / 65R17 was manufactured.

  As shown in detail in Table 1, Examples 1 to 3 are according to the present invention (R = 0.7 in Example 1, R = 0.5 in Example 2, R = in Example 3) 0.85).

  Comparative Example 1 is not arranged in a state where protrusion widths are mixed, Comparative Example 2 is arranged in a state where protrusion widths are mixed, but R = 0.4, Comparative Example 3 Is also for R = 0.9.

  The tire of the tire size 265 / 65R17 was adjusted to an internal pressure of 200 kPa, assembled to a rim of 17 × 71 / 2JJ, mounted on a four-wheel drive vehicle, and a running test using an actual vehicle was performed.

  Steering stability was evaluated as a comprehensive evaluation mainly on lane change and cornering performance by a test driver's feeling evaluation on the test course. Evaluation was made with the value of Comparative Example 1 as an index of 100.

  The fall limit performance was measured by measuring the maximum cornering force (CF value) when the drum tester was run with a maximum load of JATMA. In this embodiment, the larger the numerical value, the lower the CF value. Evaluation was made by comparing the value of Comparative Example 1 with an index of 100.

  In the belt durability test, the belt durability test was performed using an indoor drum, and the travel distance until the belt failure occurred was displayed as an index with 100 as a comparative example.

The above evaluation results are shown in Table 1.
The above three evaluations indicate that the larger the index, the better the performance, and it was judged that there was a performance difference at 5% or more.

  As can be seen from Table 1, according to the present invention, it can be seen that a tire for a passenger car having both fall-over limit performance and steering stability is realized.

  Further, if the belt end region is larger than 0.05 × W1, a problem occurs in steering stability.

FIG. 1 is a partial cross-sectional view in the tire meridian direction for explaining a pneumatic tire for a passenger car according to the present invention, and is a partial cross-sectional schematic model with a belt portion at the center. 2 (a), 2 (b) and 2 (c) are diagrams for explaining a pneumatic tire for a passenger car according to the present invention, in which a belt driving cord in the belt ply has a long (100% protruding) belt and a short (0%). FIG. 3 is a schematic plan view illustrating a state in which protrusions are alternately arranged. FIG. 3 is a schematic model diagram for explaining the mixed state in the protruding width W2. 4 (a), 4 (b), 4 (c), and 4 (d) are diagrams illustrating a pneumatic tire for a passenger car other than the present invention, and are schematic plan views depicting an arrangement of driving cords as a model. . FIGS. 5 (a) and 5 (b) are diagrams for explaining another embodiment of the pneumatic tire for passenger cars of the present invention, and are schematic plan views depicting the arrangement of driving cords as a model.

Explanation of symbols

1: Pneumatic tire for passenger cars 2: Tread 3: Carcass 4: Carcass ply 5: Belt ply (first belt)
6: Belt ply (second belt)
7: Belt cover layer 8: Belt cover layer 9: Belt cord (cord in which the protruding width W2 is 100% of the width of the region E)
10: Belt cord (a cord whose protruding width W2 is 0% of the width of the region E)
11: Belt cord 12: Belt cord (a cord whose protruding width W2 is 35% of the width of the region E)
13: Belt cord (a cord whose protruding width W2 is 0% of the width of the region E)
14: Belt cord (cord in which the protruding width W2 is 65% of the width of the region E)
E: A region having a width of 0.05 times the belt ply width W1 from the end of the belt ply to the tire inward direction L: tire equator line θ: inclination angle W of the cord with respect to the tire equator line W1: belt ply width W2: steel Projection width to area E of cord terminal

Claims (8)

  In a pneumatic tire in which at least two plies of a belt ply formed by inclining a steel cord with respect to the tire equator line are arranged on the outer side in the tire radial direction of a carcass ply formed by radially arranging carcass cords, at least one belt ply In the region E having a width 0.05 times the belt ply width W1 from the outermost end of the tire to the tire inner side, the protruding width W2 of the steel cord terminal to the region E is different along the tire circumferential direction. The ratio R of the number n in which the protrusion width W2 of the steel cord terminal to the region E with respect to the number N of steel cords inside the tire than the region E is 75% or less of the width of the region E (= n / N ) Is 0.5 to 0.85, a pneumatic tire for passenger cars.   The ratio R (= n / N) of the number n in which the protrusion width W2 of the steel cord terminal to the region E with respect to the number N of steel cords inside the tire from the region E is 75% or less of the width of the region E is 0. The pneumatic tire for passenger cars according to claim 1, wherein the tire is 50 to 0.7.   When mixing along the tire circumferential direction so that the protruding width W2 of the steel cord terminal to the region E is different, the protruding width W2 of the steel cord terminal to the region E is 75% or less of the width of the region E. 2. The steel cords and the steel cords whose protruding widths W2 are larger than 75% of the width of the region E and within 100% are alternately arranged one by one. Or the pneumatic tire for passenger cars of 2.   When mixing along the tire circumferential direction so that the protruding width W2 of the steel cord terminal to the region E is different, the protruding width W2 of the steel cord terminal to the region E is 75% or less of the width of the region E. The steel cord and the steel cord whose protruding width W2 is larger than 75% of the width of the region E and within 100% are alternately arranged for the same number of plural cords. The pneumatic tire for passenger cars according to claim 1 or 2.   When mixing along the tire circumferential direction so that the protruding width W2 of the steel cord terminal to the region E is different, the protruding width W2 of the steel cord terminal to the region E is 75% or less of the width of the region E. One of the steel cords and the steel cord having the protrusion width W2 larger than 75% of the width of the region E and within 100% is one or more, and the other is different from the plurality of the one. The pneumatic tire for a passenger car according to claim 1 or 2, wherein the plurality of tires are alternately arranged.   Two belt plies are used, and the steel cord driving of the inner layer side ply is mixed along the tire circumferential direction so that the protruding width W2 of the steel cord terminal to the region E is different. The pneumatic tire for passenger cars according to claim 1, 2, 3, 4 or 5.   Two belt plies are used, and the steel cord driving of the belt ply on the outer layer side is mixed along the tire circumferential direction so that the protruding width W2 to the region E of the steel cord terminal is different. The pneumatic tire for passenger cars according to claim 1, 2, 3, 4 or 5.   Two belt plies are used, and steel cord driving of both inner layer side and outer layer side belt plies is mixed along the tire circumferential direction so that the protruding width W2 of the steel cord terminal to the region E is different. The pneumatic tire for passenger cars according to claim 1, 2, 3, 4 or 5.

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