JP2014094632A - Tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve both rim assembly property and rim fitting property of a tire.SOLUTION: A tire 10 comprises: a pair of bead parts 16 fitted to a rim; an outside bead base 16BO formed between a bead heel 16H and a bead toe 16T of the bead part 16 on a vehicle outside; and an inside bead base 16BI formed between a bead heel 16H and a bead toe 16T of the bead part 16 on a vehicle inside and has an angle α1 with respect to a tire axial direction AX on the bead toe 16T side larger than an angle α2 with respect to a tire axial direction AX on the bead toe 16T side on the outside bead base 16BO.

Description

  The present invention relates to a tire, and more particularly to a pneumatic run-flat tire.

  The tire includes a pair of bead portions fitted to the rim. For such a tire, improving the rim assembly property and increasing the fitting force of the bead portion to the rim (rim fitting property) are mutually contradictory properties, and how to balance these is important. It is a difficult issue.

  Therefore, Patent Document 1 discloses a tire in which the bead base of the bead portion has at least an angle with respect to the tire axial direction on the bead heel side that is larger on the outer side than the inner side of the vehicle.

JP 2006-347320 A

However, in the tire described in Patent Document 1, the rim fitability of the bead portion on the outside of the vehicle is enhanced, while the rim fitability of the bead portion on the inside of the vehicle is lowered.
If the steering wheel is rotated while driving at a very low air pressure (50 kPa or less), a so-called buckling (a phenomenon in which the side part bends) occurs on the inner side part of the vehicle, and the hump part of the rim is attached to the tire bead part on the inner side of the vehicle. Since a large force in the direction of getting on acts, it is preferable to improve the rim fitting property inside the vehicle. On the other hand, the bead portion on the outside of the vehicle has a great influence on the rim assemblability (easy to attach to the rim), and therefore it is preferable to improve the rim assemblability.
In view of the above facts, an object of the present invention is to provide a tire having both rim assembling property and rim fitting property.

    According to the configuration of the first aspect, since the angle on the beat toe side with respect to the tire axial direction on the inner beat base is larger than the angle on the beat toe side with respect to the tire axial direction on the outer bead base, By increasing the contact pressure and increasing the frictional force between them, the fitting force of the bead portion inside the vehicle, that is, the rim fitting property can be enhanced. In addition, since the bead toe angle of the outer bead base with respect to the tire axial direction is smaller than the angle of the inner bead base with respect to the tire axial direction of the bead toe, it is possible to improve the rim assembly property of the bead portion outside the vehicle.

  According to the second aspect, by setting the angle of the inner beat base to 18 degrees or more, the rim fitting property can be improved as compared with the conventional tire. Further, by setting the angle of the outer bead base to 15 degrees or less, it is possible to secure the rim assembling property and to suppress the fitting pressure (the required filling air pressure when fitting the tire to the rim).

If it is Claim 3, the difference of a fitting force between a pair of bead part can be suppressed, and it can suppress giving influences, such as partial wear, to a tire.
If it is Claim 4, generation | occurrence | production of an external appearance defect etc. can be suppressed.
If it is Claim 5, it can suppress that the fitting force of the bead part in a vehicle outer side, ie, rim fitting property, becomes too low.

If the tire cross-section height is 100 mm or more, so-called buckling (a phenomenon in which the side portion bends) easily occurs on the side portion inside the vehicle when the steering wheel is rotated during traveling. It is preferable to improve the rim fitting property of the bead portion inside the vehicle.
According to the sixth aspect, when the steering wheel is rotated during traveling at a very low air pressure (50 kPa or less), a so-called buckling (a phenomenon in which the side portion is bent) easily occurs on the side portion inside the vehicle, but a very low air pressure (50 kPa). In the run flat tire provided with the side reinforcing rubber that is assumed to travel in the following), it is preferable to improve the rim fitting property of the bead portion inside the vehicle using the configuration of the first aspect. Moreover, since the bead part in the vehicle outer side has a larger influence on rim assemblability, it is preferable to improve the rim assemblage using the configuration of the first aspect.

  According to the present invention, it is possible to provide a tire that achieves both rim assembly and rim fitting.

FIG. 1 is a cross-sectional view taken along the rotational axis of a pneumatic tire according to an embodiment of the present invention.

Hereinafter, embodiments will be described and embodiments of the present invention will be described.
FIG. 1 is a cross-sectional view taken along the rotational axis of a pneumatic tire according to an embodiment of the present invention. As shown in FIG. 1, a pneumatic tire 10 according to an embodiment of the present invention is a run-flat tire for a passenger car.
In the pneumatic tire 10, a pair of side portions 14 and a pair of bead portions 16 are continuous from both ends of the cylindrical crown portion 12 toward the inside in the tire radial direction. Each of the pair of bead portions 16 is disposed on the vehicle outer side and the vehicle inner side when fitted to the standard rim 17 and includes a bead filler 18 and a bead core 20.
The tire cross-sectional height SH of the pneumatic tire 10 is not particularly limited, but is, for example, 100 mm or more when buckling is likely to occur on the side portion 14 inside the vehicle when the steering wheel is rotated during traveling. In addition to the bead portion 16, the pneumatic tire 10 further includes a carcass layer 22, a belt layer 24, and a tread portion 26 having a tread pattern.

  The standard rim 17 is a rim defined in the year 2012 version of JATMA (Japan Automobile Tire Association). Outside Japan, the load is the maximum load (maximum load capacity) of a single wheel at the applicable size described in the following standard, and the internal pressure is the maximum load (maximum load) of a single wheel described in the following standard. The rim is a standard rim (or “Applied Rim” or “Recommended Rim”) in an applicable size described in the following standards.

  The tire cross-section height SH means that the tire is assembled to the standard rim 17 in the applicable size specified in the YEAR BOOK and filled with 80% of the air pressure with respect to the maximum load in the applicable size / ply rating specified in the YEAR BOOK. It refers to the height of the cross section in the unloaded state.

  The standard rim 17 includes a rim flange 17F as a portion that contacts the bead heel 16H of the bead portion 16 when the rim is mounted, a bead seat 17S as a portion that contacts the bead base 16B of the bead portion 16, and a toe tip 16Te of the bead toe 16T of the bead portion 16. A hump portion 17H is provided as a raised portion provided so as not to fall off inward in the tire width direction.

  In this pneumatic tire 10, side reinforcing rubber having a crescent-shaped cross section (a shape in which the thickness gradually decreases toward the inner side in the tire radial direction and the outer side in the tire radial direction) on the inner surface side of the carcass layer 22 in the side portion 14. Layer 28 is provided.

The bead portion 16 outside the vehicle has an outer bead base 16BO as a bead base 16B formed between the bead heel 16H and the bead toe 16T. The bead portion 16 on the vehicle inner side has an inner bead base 16BI as a bead base 16B formed between the bead heel 16H and the bead toe 16T.
The outer bead base 16BO and the inner beat base 16BI are composed of two inclined surfaces 30, 32, respectively. The inclined surface 30 on the bead toe 16T side is longer than the inclined surface 32 on the bead heel 16H side, and extends beyond the center in the width direction of the bead base 16B.

The inclined surface 30 of the inner bead base 16BI has an inclination angle α1 with respect to the tire axial direction AX. Further, the inclined surface 32 of the inner bead base 16BI has an inclination angle β1 with respect to the tire axial direction AX.
On the other hand, the inclined surface 30 of the outer bead base 16BO has an inclination angle α2 with respect to the tire axial direction AX. Further, the inclined surface 32 of the outer bead base 16BO has an inclination angle β2 with respect to the tire axial direction AX.

  In this embodiment, when the bead portion 16 is in a free state (before fitting to the standard rim 17), the inclination angle of the inclined surface 30 of the inner bead base 16BI (the tire axial direction on the bead toe 16T side of the inner bead base 16BI). (Angle with respect to AX) α1 is larger than the inclination angle of the inclined surface 30 of the outer bead base 16BO (angle with respect to the tire axial direction AX on the bead toe 16T side of the outer bead base 16BO) α2.

The relationship between the inclination angles α1 and β1 is not particularly limited, but α1 is larger than β1 in this embodiment. Similarly, the relationship between the inclination angles α2 and β2 is not particularly limited, but α2 is larger than β2 in the present embodiment.
Further, the relationship between the inclination angles β1 and β2 is not particularly limited, but in the present embodiment, β1 is smaller than β2 in order to maintain the balance of the entire bead portion 16 from the relationship between α1 and α2.
The bead heel 16H refers to the intersection of the extension lines of the inner peripheral surface and the outer surface of the bead portion 16 that are in contact with the bead seat 17S and the rim flange 17F of the standard rim 17 to which the tire 10 is assembled. When a straight line parallel to the rotation axis is drawn, the intersection of this and the tire surface shall be indicated. Further, the bead toe 16T is based on the intersection of the extension lines of the inner peripheral surface of the bead portion 16 that contacts the bead seat 17S of the standard rim 17 to which the tire 10 is assembled and the tire inner surface of the bead portion 16 that does not contact the rim. When a straight line that passes through this and is parallel to the tire rotation axis is drawn, the point of intersection between the tire and the tire surface is indicated.

Next, the effect | action of the pneumatic tire 10 of this embodiment is demonstrated.
When the steering wheel is rotated during traveling of the vehicle equipped with the pneumatic tire 10 of the present embodiment, buckling may occur in the side portion 14 on the vehicle inner side. In particular, the pneumatic tire 10 of the present embodiment is a run-flat tire, and the tire cross-section height SH is 100 mm or more, so buckling is likely to occur. For this reason, it is preferable to improve the rim fitting property inside the vehicle.
On the other hand, the bead portion 16 on the outside of the vehicle has a great influence on the rim assemblability (ease of being attached to the rim), and therefore it is preferable to improve the rim assemblability.
The reason why the bead portion 16 on the outer side of the vehicle has a greater influence on the rim assembly is as follows. In the operation of assembling the pneumatic tire 10 to the standard rim 17 by the rim assembling machine, each of the bead portion 16 corresponding to the inside of the vehicle and the bead portion 16 corresponding to the outside of the vehicle needs to get over the rim flange 17F. The bead portion in contact with the flange 17F is a bead heel 16H on the vehicle inner side and a bead toe 16T on the vehicle outer side. When the bead toe 16T gets over the rim flange, it comes into contact with the rim flange 17F so that damage such as rubber chipping is likely to occur, and the catch at the tip of the bead toe 16T becomes resistance, and the bead heel 16H comes into contact with the inside of the vehicle. However, rim assembly workability is reduced.

Therefore, in the pneumatic tire 10 of the present embodiment, the angle α1 with respect to the tire axial direction AX in the inner bead base 16BI is larger than the angle α2 with respect to the tire axial direction AX in the outer bead base 16BO. As a result, the contact pressure of the bead toe portion 16Te on the vehicle inner side to the standard rim 17 increases, and the frictional force between them increases, so that the fitting force of the bead portion 16 on the vehicle inner side, that is, the rim fitting property is increased. Can be increased.
Further, since the angle α2 with respect to the tire axial direction AX in the outer bead base 16BO is smaller than the angle α1 with respect to the tire axial direction AX in the inner bead base 16BI, the rim assembly property of the bead portion 16 on the vehicle outer side can be improved.

  The angle α1 of the inner beat base 16BI is preferably 18 degrees or more, and the angle α2 of the outer beat base 16BO is preferably 15 degrees or less. This is because, by setting the angle α1 of the inner beat base 16BI to 18 degrees or more, the rim fitting property can be improved as compared with the conventional tire. Further, by setting the angle α2 of the outer bead base 16BO to 15 degrees or less, it is possible to improve the rim assembly property and to suppress the fitting pressure (the necessary filling air pressure when fitting the tire to the rim).

The angle difference between the angle α1 of the inner beat base 16BI and the angle α2 of the outer beat base 16BO is preferably less than 10 degrees. This is because a difference in fitting force between the pair of bead portions 16 can be suppressed, and the influence of uneven wear or the like on the pneumatic tire 10 can be suppressed.
Further, the angle α1 of the inner beat base 16BI is preferably 30 degrees or less. This is because the appearance defects can be suppressed.
Further, the angle α2 of the outer beat base 16BO is preferably 10 degrees or more. This is because it is possible to suppress the fitting force of the bead portion on the vehicle outer side, that is, the rim fitting property from becoming too low.

<< Example 1 >>
For the tire of Example 1, the configuration of the run-flat tire described in the above embodiment was used. The tire size was 215 / 60R16. The internal pressure of the tire was 0 kPa. The angle α1 of the inner bead base with respect to the tire axial direction on the beat toe side was 17 degrees, and the angle α2 of the outer bead base with respect to the tire axial direction on the beat toe side was 15 degrees.
The size of the rim to be fitted to the tire was 6.5J-16. The vehicle on which the tires are mounted is a vehicle having a total body weight of 2 t.
<< Example 2 >>
In the tire of Example 2, the angle α1 with respect to the tire axial direction on the beat toe side of the inner bead base was 18 degrees, and the angle α2 with respect to the tire axial direction on the beat toe side of the outer bead base was 10 degrees. Other configurations are the same as those in the first embodiment.
<< Example 3 >>
In the tire of Example 3, the angle α1 with respect to the tire axial direction on the beat-to-side in the inner bead base was 18 degrees, and the angle α2 with respect to the tire axial direction on the beat-to-side in the outer bead base was 15 degrees. Other configurations are the same as those in the first embodiment.
<< Example 4 >>
In the tire of Example 4, the angle α1 with respect to the tire axial direction on the beat-to-side in the inner bead base was 25 degrees, and the angle α2 with respect to the tire axial direction on the beat-to-side in the outer bead base was 15 degrees. Other configurations are the same as those in the first embodiment.
<< Example 5 >>
In the tire of Example 5, the angle α1 with respect to the tire axial direction on the beat-to-side in the inner bead base was 30 degrees, and the angle α2 with respect to the tire axial direction on the beat-to-side in the outer bead base was 15 degrees. Other configurations are the same as those in the first embodiment.
<< Example 6 >>
In the tire of Example 6, the angle α1 with respect to the tire axial direction on the beat toe side in the inner bead base was 31 degrees, and the angle α2 with respect to the tire axial direction on the beat toe side in the outer bead base was 15 degrees. Other configurations are the same as those in the first embodiment.
<< Example 7 >>
In the tire of Example 7, the angle α1 with respect to the tire axial direction on the beat toe side in the inner bead base was 18 degrees, and the angle α2 with respect to the tire axial direction on the beat toe side in the outer bead base was 16 degrees. Other configurations are the same as those in the first embodiment.
<< Example 8 >>
In the tire of Example 2, the angle α1 with respect to the tire axial direction on the beat toe side in the inner bead base was 18 degrees, and the angle α2 with respect to the tire axial direction on the beat toe side in the outer bead base was 9 degrees. Other configurations are the same as those in the first embodiment.
<< Comparative Example 1 >>
In the tire of Comparative Example 1, the angle α1 with respect to the tire axial direction on the beat-to-side in the inner bead base was 15 degrees, and the angle α2 with respect to the tire axial direction on the beat-to-side in the outer bead base was 15 degrees. Other configurations are the same as those in the first embodiment.
<< Comparative Example 2 >>
In the tire of Comparative Example 1, the angle α1 with respect to the beat-to-side tire axial direction on the inner bead base was 18 degrees, and the angle α2 with respect to the beat-to-side tire axial direction on the outer bead base was 18 degrees. Other configurations are the same as those in the first embodiment.
<< Comparative Example 3 >>
In the tire of Comparative Example 1, the angle α1 with respect to the beat-to-side tire axial direction on the inner bead base was 15 degrees, and the angle α2 with respect to the beat-to-side tire axial direction on the outer bead base was 25 degrees. Other configurations are the same as those in the first embodiment.
<< Comparative Example 4 >>
In the tire of Comparative Example 1, the angle α1 with respect to the tire axial direction on the beat-to-side in the inner bead base was 25 degrees, and the angle α2 with respect to the tire axial direction on the beat-to-side in the outer bead base was 25 degrees. Other configurations are the same as those in the first embodiment.

<< Evaluation >>
Next, while sequentially changing the tire mounted on the vehicle described in the first embodiment to any one of the tires according to the first to eighth embodiments and the first to fourth comparative embodiments, the rim assembly property and the rim fitting of each tire are performed. Sex was evaluated.
In this evaluation, a vehicle equipped with the tire to be evaluated was first driven to run at a speed of 20 km / h for 5 km. Next, it entered a turning circuit with a radius of curvature of 25 m at a predetermined speed, and stopped at the 1/3 round position of the turning circuit twice continuously. When the bead heel did not get over the hump part of the rim, the predetermined speed was increased until the bead heel part got over the hump part of the rim.

Table 1 shows the tires according to each of the examples and comparative examples. The overspeed when the bead heel part passes over the hump part of the rim, the presence or absence of damage to the bead when assembling the rim, the fit pressure, the evaluation of the rim assemblability, This is a summary of the evaluation of rim fitability.
In addition, the evaluation “A” of the rim fitting property in Table 1 means that the overtaking speed is 35 km / h or more. The evaluation “B” of the rim fitting property means that the overpass speed is 31 km / h or more and less than 35 km / h. The evaluation “C” of the rim fitting property means that the passing speed is less than 31 km / h.
Moreover, the evaluation “A” of the rim assembly property in Table 1 means that there is no bead damage during the rim assembly and the fit pressure is 130 kPa or less. The evaluation “B” of the rim assembling property means that there is no bead damage when assembling the rim, and the fitting pressure is more than 130 kPa. The evaluation “C” of the rim assembly property means that there is a bead damage at the time of rim assembly.

As described above, as shown in Table 1, the tires according to Examples 1 to 8 satisfy the condition of angle α1> angle α2, and both evaluation of rim fitting property and rim assembly property is “B” or “A”. Met. On the other hand, the tires according to Comparative Examples 1 to 4 did not satisfy the condition of α1> α2, and at least one of the evaluation of the rim fitting property and the rim assembling property was “C”.
Further, the tires according to Example 2 to Example 8 in which the angle α1 is 18 degrees or more have a higher overpass speed of 2 km / h or more than the tire according to Example 1 in which the angle α1 is 17 degrees. It can be said that the rim fitting property was improved.
Furthermore, it can be said that the tires according to Examples 1 to 6 and 8 in which the angle α2 was 15 degrees or less were able to suppress the fitting pressure as compared with the tire according to Example 7 in which the angle α2 was 16 degrees.
Further, the tires according to Examples 1 to 3, 7, and 8 in which the difference between the angle α1 and the angle α2 is less than 10 degrees are the same as the tires according to Examples 4 to 6 in which the difference between the angle α1 and the angle α2 is 10 degrees or more. In comparison, there was no uneven wear on the tires.
Further, in the tires according to Examples 1 to 5, 7, and 8 in which the angle α1 was set to 30 degrees or less, no appearance defect occurred during the production. However, in the tire according to Example 6 in which the angle α1 was 31 degrees, an appearance defect occurred at the time of manufacture. Therefore, when the angle α1 is set to 30 degrees or less, it can be said that the appearance defects can be suppressed.

  In addition, in the tires according to Examples 1 to 7 in which the angle α2 was set to 10 degrees or more, even though a gap was generated inside the vehicle, no gap was generated on the outside of the vehicle, but the angle α2 was set to 9 degrees. In the tire according to No. 8, when a gap was generated inside the vehicle, a gap was also generated outside the vehicle. Therefore, when the angle α2 is 10 degrees or more, it can be said that the fitting force of the bead portion on the outside of the vehicle, that is, the rim fitting property can be suppressed from becoming too low.

10 Pneumatic tire (tire), 14 side part, 16 bead part, 16T bead toe, 16H bead heel, 16B bead base, 16BO outer beat base, 16BI inner bead base, 17 standard rim (rim), 28 side reinforcing rubber layer

Claims (6)

A pair of beads fitted to the rim;
An outer bead base formed between a bead heel and a bead toe of the bead portion outside the vehicle;
An inner beat base formed between a bead heel and a bead toe of the bead portion inside the vehicle, and an angle with respect to a tire axial direction on a beat toe side is larger than an angle with respect to a tire axial direction on a beat toe side on an outer bead base;
Tire with. The angle of the inner beat base is 18 degrees or more, and the angle of the outer beat base is 15 degrees or less;
The tire according to claim 1. The angle difference between the angle of the inner beat base and the angle of the outer beat base is less than 10 degrees.
The tire according to claim 1 or claim 2. The angle of the inner beat base is 30 degrees or less,
The tire according to any one of claims 1 to 3. The angle of the outer beat base is 10 degrees or more,
The tire according to any one of claims 1 to 4. A side reinforcing rubber disposed inside a side portion connected to the pair of bead portions;
A tire according to any one of claims 1 to 5, comprising: