JP2013189165A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire coping with both of operation stability and riding comfort, and suppressing ply steer.SOLUTION: A pneumatic tire is structured by stretching a carcass layer 4 between a pair of bead parts 3 and 3, rolling up the carcass layer 4 to the outside from the inside of a tire around a bead core 5 embedded in each bead part 3, and disposing a belt layer 7 in a tread part 1 on a peripheral side of the carcass layer 4, and a mounting direction thereof to a vehicle is specified. The belt layer 7 includes arc-like reinforcing cords C, and the arc-like reinforcing cords C are disposed so as to project outside when mounted in the vehicle. The outside rolling-up height TUHof the carcass layer 4 when mounted in the vehicle is larger than the inside rolling-up height TUHof the carcass layer 4 when mounted in the vehicle.

Description

  The present invention relates to a pneumatic tire provided with a belt layer on the outer peripheral side of a carcass layer in a tread portion. More specifically, the pneumatic tire is compatible with steering stability and riding comfort and suppresses price tear. About.

  In pneumatic tires, it is required to achieve both steering stability and riding comfort at a high level. However, in order to improve the steering stability, it is necessary to increase the tire rigidity, whereas in order to improve the riding comfort, it is necessary to reduce the tire rigidity. Therefore, it is a difficult task to achieve both steering stability and riding comfort.

  On the other hand, in a pneumatic tire in which a belt layer is disposed on the outer peripheral side of the carcass layer in the tread portion, there is a vehicle flow problem that when the vehicle is moved straight away from the handle, the vehicle bends and flows to one side. As a cause of such a vehicle flow, there is a price tear generated when the reinforcing cord of the belt layer is inclined with respect to the tire circumferential direction.

  In contrast, the belt layer reinforcing cord is bent at the position of the tire equator line, and the cord angle of the belt layer is made different between the inner region and the outer region when the vehicle is mounted, thereby causing a price theater that acts on each region. There has been proposed a pneumatic tire that offsets the tire and suppresses the occurrence of price tear (for example, see Patent Document 1).

  However, in such a pneumatic tire, the inclination of the reinforcing cord changes abruptly on the tire equator, so that the behavior of the tire changes abruptly in a transitional state from straight running to turning or turning to straight running. There's a problem. In addition, since all the reinforcing cords constituting the belt layer are folded back along the tire equator line, there is a disadvantage that productivity of the pneumatic tire is lowered. Of course, such a pneumatic tire does not have the effect of improving both handling stability and riding comfort.

JP 2009-90675 A

  An object of the present invention is to provide a pneumatic tire in which handling stability and riding comfort are compatible and price tear is suppressed.

In order to achieve the above object, the pneumatic tire of the present invention has a carcass layer mounted between a pair of bead portions, and the carcass layer is wound around the bead core embedded in each bead portion from the inside of the tire to the outside. In a pneumatic tire having a configuration in which a belt layer is disposed on the outer peripheral side of the carcass layer in the tread portion, and a mounting direction for the vehicle is designated,
The belt layer includes an arc-shaped reinforcing cord, the arc-shaped reinforcing cord is arranged so as to protrude outward when the vehicle is mounted, and the winding height TUH _{out of the} carcass layer when the vehicle is mounted is The carcass layer is characterized by being larger than the inner winding height TUH _in when the vehicle is mounted.

  In the present invention, since the arc-shaped reinforcing cords in the belt layer are arranged so as to protrude outward when the vehicle is mounted, the angle of the reinforcing cord with respect to the tire circumferential direction is outside on the belt layer when the vehicle is mounted. In-plane bending rigidity is increased because the arrangement density is increased with decreasing size. On the other hand, on the inner side when the belt layer is mounted on the vehicle, the angle of the arc-shaped reinforcing cord with respect to the tire circumferential direction is increased and the arrangement density is reduced, so that the out-of-plane bending rigidity is reduced. In general, there are many vehicles with negative camber setting when going straight, but when pneumatic tires are attached to the vehicle with negative camber, the vehicle inner part of the tread part with low out-of-plane bending rigidity is mainly grounded when going straight. The comfort is improved and the steering stability is improved because a load is applied to the vehicle outer portion of the tread portion having a high in-plane bending rigidity during turning. Further, when traveling straight, the vehicle inner portion of the tread portion is grounded, and the price tear component due to the inclination of the reinforcing cord of the belt layer is reduced, so that the vehicle flow can be suppressed and the straight traveling performance can be improved. In addition, since the reinforcement cord is arranged in an arc shape and the inclination angle of the reinforcement cord gradually changes, it is possible to moderate the behavior change in a transitional state from straight running to turning or from turning to straight running. .

Further, according to the present invention, the steering height is improved by relatively increasing the outer winding height TUH _out when the carcass layer is mounted on the vehicle, and the inner winding height TUH _in is relatively increased when the carcass layer is mounted on the vehicle. Riding comfort is improved by making it smaller. In particular, when the above-described asymmetric structure of the winding height of the carcass layer is used in combination with a belt layer made of an arc-shaped reinforcing cord, the steering stability without excessively increasing the outer winding height TUH _out when the carcass layer is mounted on the vehicle. In addition, since it is possible to achieve both a high level of ride comfort, it is possible to avoid the height of the carcass layer that affects the productivity.

In the present invention, the outer winding height TUH _{out when} the carcass layer is mounted on the vehicle is 1.2 × TUH _in ≦ TUH _out ≦ 1.6 × TUH _in relative to the inner winding height TUH _in when the carcass layer is mounted on the vehicle. It is preferable that the relationship is As a result, it is possible to achieve both steering stability and riding comfort while reliably avoiding that the winding height of the carcass layer affects the productivity.

  The end of the arc-shaped reinforcing cord is preferably positioned at the inner end of the belt layer when the vehicle is mounted, and the apex of the arc-shaped reinforcing cord is preferably positioned at the outer end of the belt layer when mounted on the vehicle. As a result, it is possible to sufficiently ensure the effect of achieving both steering stability and riding comfort.

  The angle θ of the tangent line of the arc-shaped reinforcing cord at the inner end of the belt layer when the vehicle is mounted with respect to the tire circumferential direction is preferably 50 ° to 90 °. Thereby, it is possible to sufficiently ensure the riding comfort improvement effect.

  The pitch P in the tire circumferential direction at the end of the arc-shaped reinforcing cord at the inner end when the belt layer is mounted on the vehicle is preferably 1.5 mm to 4.5 mm. Thereby, it is possible to sufficiently ensure the riding comfort improvement effect while maintaining the exercise performance and durability of the pneumatic tire in good condition.

It is meridian sectional drawing which shows the pneumatic tire which consists of embodiment of this invention. It is an expanded view which shows the principal part of the belt layer in the pneumatic tire of this invention. FIG. 3 is a development view showing one reinforcing cord extracted from the belt layer of FIG. 2. It is an expanded view which shows the modification of the belt layer in the pneumatic tire of this invention.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a pneumatic tire according to an embodiment of the present invention, and FIGS. 2 and 3 show a belt layer of the pneumatic tire. This pneumatic tire is a tire in which the mounting direction with respect to the vehicle is specified. 1 to 3, IN is the inside of the vehicle when the vehicle is mounted, and OUT is the outside of the vehicle when the vehicle is mounted.

  As shown in FIG. 1, the pneumatic tire of this embodiment includes a tread portion 1 that extends in the tire circumferential direction and has an annular shape, and a pair of sidewall portions 2 that are disposed on both sides of the tread portion 1. A pair of bead portions 3 are provided inside the sidewall portions 2 in the tire radial direction. A carcass layer 4 is mounted between the pair of bead portions 3 and 3. The carcass layer 4 includes a plurality of reinforcing cords extending in the tire radial direction, and is wound up around the bead core 5 disposed in each bead portion 3 from the tire inner side to the outer side. As a reinforcing cord for the carcass layer 4, an organic fiber cord is generally used, but a steel cord may be used. A bead filler 6 made of a rubber composition having a triangular cross-section is disposed on the outer periphery of the bead core 5.

  On the other hand, at least one belt layer 7 is embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. Each belt layer 7 is composed of a plurality of reinforcing cords and has a specific structure as described later. On the outer peripheral side of the belt layer 7, at least one belt cover layer 8 in which reinforcing cords are arranged at an angle of 5 ° or less with respect to the tire circumferential direction is disposed for the purpose of improving high-speed durability. . The belt cover layer 8 preferably has a jointless structure in which at least one reinforcing cord is stretched and rubber-coated strip material is continuously wound in the tire circumferential direction. Further, the belt cover layer 8 may be disposed so as to cover the entire width direction of the belt layer 7, or may be disposed so as to cover only the outer edge portion of the belt layer 7 in the width direction. As the reinforcing cord of the belt cover layer 8, an organic fiber cord such as nylon or aramid is preferably used.

  In the pneumatic tire, as shown in FIG. 2, the belt layer 7 includes a plurality of reinforcing cords C curved in an arc shape, and the reinforcing cords C are arranged so as to protrude outward when the vehicle is mounted. Has been. That is, as shown by paying attention to one reinforcing cord C in FIG. 3, the end portion e of the arc-shaped reinforcing cord C is located at the inner end portion 7i of the belt layer 7 when the vehicle is mounted, and the arc-shaped reinforcing cord C Of the belt layer 7 is located at the outer end 7o when the vehicle is mounted.

  In the pneumatic tire described above, all the arc-shaped reinforcing cords C constituting the belt layer 7 are arranged so as to protrude outward when the vehicle is mounted. Since the angle with respect to the tire circumferential direction R decreases and the arrangement density increases, the in-plane bending rigidity increases. On the other hand, on the inner side when the belt layer 7 is mounted on the vehicle, the angle of the arc-shaped reinforcing cord C with respect to the tire circumferential direction R increases and the arrangement density decreases, so that the out-of-plane bending rigidity decreases. The pneumatic tire configured as described above is attached to the vehicle with a negative camber. For this reason, when the vehicle goes straight, the vehicle inner portion of the tread portion 1 having low out-of-plane bending rigidity is mainly grounded, so that riding comfort is improved. On the other hand, when the vehicle turns, a load is applied to the vehicle outer side portion of the tread portion 1 having high in-plane bending rigidity, so that the steering stability is improved.

  In the pneumatic tire, the vehicle inner portion of the tread portion 1 is mainly grounded when the vehicle goes straight, and the price tear component due to the inclination of the reinforcing cord C of the belt layer 7 is reduced. Since the price tear component is suppressed in this way, the vehicle flow can be suppressed and the straight traveling performance can be improved. Moreover, since the reinforcing cord C is arranged in an arc shape and the inclination angle of the reinforcing cord C gradually changes, the behavior changes in a transitional state in which the vehicle transitions from straight running to turning, or the vehicle moves from turning. It is possible to moderate the behavior change in a transitional state where the vehicle moves straight ahead.

Further, in the pneumatic tire, the outer winding height TUH _{out when} the carcass layer 4 is mounted on the vehicle is set to be larger than the inner winding height TUH _in when the carcass layer 4 is mounted on the vehicle. The winding heights TUH _out and TUH _in of the carcass layer 4 can be measured in a state where a cut sample cut out from a part on the tire circumference is assembled to a standard rim. At that time, the peripheral length of the cut sample may be 10 mm or more, for example, 20 mm.

Thus, the outer winding height TUH _out when the carcass layer 4 is mounted on the vehicle is relatively increased to improve the handling stability, and the inner winding height TUH _in when the carcass layer 4 is mounted on the vehicle is relatively increased. Riding comfort can be improved by reducing the size. In addition, when trying to make the improvement effect of steering stability and riding comfort compatible only on the basis of the asymmetric structure of the hoisting height of the carcass layer 4, the outer hoisting height TUH _out of the carcass layer 4 when the vehicle is mounted is excessively increased. As a result, the tire productivity may be hindered. On the other hand, when the asymmetric structure of the winding height of the carcass layer 4 described above is used in combination with the belt layer 7 made of the arc-shaped reinforcing cord C, the winding height TUH _out on the outer side of the carcass layer 4 when the vehicle is mounted is excessively increased. It is possible to achieve both a high level of handling stability and riding comfort without increasing the size. Therefore, it can be avoided that the productivity of the tire is hindered due to the winding height of the carcass layer 4.

When the carcass layer 4 is mounted on the vehicle, the outer winding height TUH _out is 1.2 × TUH _in ≦ TUH _out ≦ 1.6 × TUH _in with respect to the inner winding height TUH _in when the vehicle is mounted. good. As a result, it is possible to achieve both steering stability and riding comfort while reliably avoiding that the winding height of the carcass layer 4 affects the productivity. If the outer roll-up height TUH _out is smaller than 1.2 x TUH _in when the vehicle is mounted, the effect of achieving both characteristics will be insufficient. Conversely, if it exceeds 1.6 x TUH _in , the tire productivity will decrease. There is a fear. The inner winding height TUH _in of the carcass layer 4 when the vehicle is mounted is set to 15 mm or more, and the outer winding end of the carcass layer 4 when the vehicle is mounted is on the inner side in the tire radial direction from the outer end of the belt layer 7 in the tire width direction. It is desirable to position it.

  FIG. 4 shows a modification of the belt layer in the pneumatic tire of the present invention. 4, the same components as those in FIGS. 2 and 3 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 4, the angle θ with respect to the tire circumferential direction R of the tangent of the arc-shaped reinforcing cord C at the inner end 7i of the belt layer 7 when the vehicle is mounted is preferably in the range of 50 ° to 90 °, more preferably 80. It is set in the range of ° to 90 °. Thereby, it is possible to sufficiently ensure the riding comfort improvement effect. When the angle θ is less than 50 °, the out-of-plane bending rigidity of the vehicle inner side portion of the tread portion 1 is increased, so that the riding comfort improvement effect is lowered. Further, since the price tear component caused by the inclination angle θ of the reinforcing cord C with respect to the tire circumferential direction R also gradually increases, it becomes difficult to suppress the vehicle flow.

  Further, the pitch P in the tire circumferential direction of the end e of the arc-shaped reinforcing cord C at the inner end 7i of the belt layer 7 when the vehicle is mounted is preferably in the range of 1.5 mm to 4.5 mm, more preferably 2.2 mm. It is set in the range of ˜2.8 mm. Thereby, it is possible to sufficiently ensure the riding comfort improvement effect while maintaining the exercise performance and durability of the pneumatic tire in good condition. If the pitch P is less than 1.5 mm, the cord density around the apex a of the arc-shaped reinforcing cord C in the outer portion of the belt layer 7 when the vehicle is mounted becomes excessive, and the rigidity of the belt layer 7 becomes too large. On the other hand, if the pitch P exceeds 4.5 mm, the rigidity of the inner portion of the belt layer 7 when the vehicle is mounted becomes too small. In any case, not only the motion performance of the pneumatic tire is deteriorated but also the durability is lowered. The pitch P at the end e of the arc-shaped reinforcing cord C is the distance in the tire circumferential direction between the center points of a pair of reinforcing cords adjacent in the tire circumferential direction.

  The arc-shaped reinforcing cord C constituting the belt layer 7 is not particularly limited, but a steel cord is preferably used. By configuring the arc-shaped reinforcing cord C with a steel cord, it becomes easy to maintain the arrangement form of the arc-shaped reinforcing cord C.

The tire size is 195 / 65R15, a carcass layer is mounted between a pair of bead portions, the carcass layer is wound up around the bead core embedded in each bead portion from the inside of the tire to the outside, and the carcass layer in the tread portion is In a pneumatic tire having a configuration in which a belt layer is arranged on the outer peripheral side and the mounting direction with respect to the vehicle is specified, the form of the reinforcing cord constituting the belt layer, the direction of the convex portion of the reinforcing cord, and the angle θ of the reinforcing cord , The pitch P of the reinforcing cord, the inner winding height TUH _in when the carcass layer is mounted on the vehicle, the outer winding height TUH _out when the carcass layer is mounted on the vehicle, and the inner winding height TUH _in , TUH when the carcass layer is mounted on the vehicle Tires of Conventional Example 1, Comparative Examples 1 and 2 and Examples 1 to 6 _in which _out / TUH _in was set as shown _in Table 1 were manufactured.

  The form of the reinforcing cord indicates that the reinforcing cord is a steel cord having a linear shape or an arc shape. The direction of the convex portion of the reinforcing cord indicates whether the direction of the convex portion of the arc in the arc-shaped reinforcing cord is the outer side or the inner side when the vehicle is mounted. The angle θ of the reinforcement cord indicates the inclination angle with respect to the tire circumferential direction in the case of a linear reinforcement cord, and indicates the inclination angle with respect to the tire circumferential direction of the tangent at the end portion in the case of the arc-shaped reinforcement cord. The pitch P of the reinforcement cord indicates the pitch in the tire circumferential direction between the reinforcement cords adjacent to each other in the tire circumferential direction in the case of a linear reinforcement cord. The pitch in the tire circumferential direction between the ends of the reinforcing cords adjacent in the circumferential direction is shown. All the test tires were molded into the same shape using the same mold, although the internal structures were different.

  These test tires were evaluated for steering stability, riding comfort, vehicle flow and carcass folding failure rate by the following evaluation methods, and the results are also shown in Table 1.

Steering stability:
Each test tire is assembled to a wheel with a rim size of 15 x 6 J and mounted on a test vehicle with a displacement of 1300 cc. A 4 km lap test course is run at 100 km / h on an air pressure of 180 kPa, and a sensory evaluation is performed by a test driver. went. The evaluation results are shown as an index with Conventional Example 1 as 100. The larger the index value, the better the steering stability.

Ride comfort:
Each test tire is mounted on a wheel with a rim size of 15 x 6 J and mounted on a test vehicle with a displacement of 1300 cc. A straight test course with irregularities is run at 50 km / h under conditions of air pressure of 180 kPa, and sensory evaluation by a test driver Went. The evaluation results are shown as an index with Conventional Example 1 as 100. It means that riding comfort is excellent, so that this index value is large.

Vehicle flow:
Each test tire is mounted on a wheel with a rim size of 15 x 6 J and mounted on a test vehicle with a displacement of 1300 cc. A flat straight test course is run at 100 km / h under the condition of air pressure of 180 kPa, and it is handed from the steering wheel when driving straight. The distance (deflection amount) deviated from the straight line to the left and right was measured 100 m after traveling 100 m. The evaluation results are shown as an index with the conventional example 1 as 100, using the reciprocal of the measured value. A larger index value means less vehicle flow due to price tear.

Carcass folding failure rate:
For each test tire, the incidence of defective products due to insufficient folding of the carcass layer when the green tire was molded was determined. In addition, tires having a few defective parts that are not problematic in practical use were also strictly judged as defective products.

  As can be seen from Table 1, the tires of Examples 1 to 6 were all excellent in terms of evaluation items for handling stability, riding comfort, and vehicle flow in comparison with Conventional Example 1. Further, in the tires of Examples 1 to 6, no carcass layer folding failure occurred.

  On the other hand, since the roll-up height of the carcass layer was the same on the inner side and the outer side when the vehicle was mounted, the tire of Comparative Example 1 had a smaller improvement effect than Examples 1-6. In the tire of Comparative Example 2, since the winding height of the carcass layer is larger on the inner side than on the outer side when the vehicle is mounted, the improvement effect is smaller than that of Comparative Example 2.

  Next, the tire of Conventional Example 2 having the same structure as that of Conventional Example 1 except that the winding height of the carcass layer is changed, and the same structure as that of Example 1 except that the winding height of the carcass layer is changed. A tire of Example 7 having The tires of the conventional example 2 and the example 7 both have a so-called bit structure in which the carcass layer is set to have a large outer winding height when the vehicle is mounted, and the winding end is inserted between the belt layer and the carcass layer. Is.

These test tires were evaluated for steering stability, riding comfort, vehicle flow, and carcass folding failure rate by the above-described evaluation methods, and the results are also shown in Table 2. However, the steering stability, the riding comfort, and the vehicle flow were evaluated by index values with the conventional example 2 as a reference (100).

  As can be seen from Table 2, in the tire of Example 7, the evaluation items of steering stability, riding comfort, and vehicle flow were all good in comparison with Conventional Example 2. However, when a bit structure was adopted for the carcass layer and the outer winding height was excessively large when the vehicle was mounted, a slight folding failure of the carcass layer was recognized.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Carcass layer 5 Bead core 6 Bead filler 7 Belt layer 8 Belt cover layer C Arc-shaped reinforcement cord

Claims (5)

A structure in which a carcass layer is mounted between a pair of bead portions, the carcass layer is wound up around the bead core embedded in each bead portion from the inside of the tire to the outside, and a belt layer is disposed on the outer peripheral side of the carcass layer in the tread portion And a pneumatic tire for which the mounting direction with respect to the vehicle is specified.
The belt layer includes an arc-shaped reinforcing cord, the arc-shaped reinforcing cord is arranged so as to protrude outward when the vehicle is mounted, and the winding height TUH _{out of the} carcass layer when the vehicle is mounted is A pneumatic tire characterized in that it is larger than an inner winding height TUH _in when the carcass layer is mounted on a vehicle. The relationship of the outer winding height TUH _out when the carcass layer is mounted on the vehicle is 1.2 × TUH _in ≦ TUH _out ≦ 1.6 × TUH _in with respect to the inner winding height TUH _in when the carcass layer is mounted on the vehicle. The pneumatic tire according to claim 1, wherein   The end of the arc-shaped reinforcing cord is positioned at an inner end of the belt layer when the vehicle is mounted, and the apex of the arc-shaped reinforcing cord is positioned at an outer end of the belt layer when mounted on the vehicle. Item 3. The pneumatic tire according to Item 1 or 2.   The air according to any one of claims 1 to 3, wherein an angle θ of a tangent of the arc-shaped reinforcing cord at the inner end of the belt layer with respect to the tire circumferential direction is 50 ° to 90 °. Enter tire.   5. The pitch P in the tire circumferential direction of the end portion of the arc-shaped reinforcing cord at the inner end portion of the belt layer when the vehicle is mounted is 1.5 mm to 4.5 mm. The described pneumatic tire.

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