JP2008279931A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire making fitting property in rim assembly in a tire attached to an offset type wheel and rim removal-resistance after rim assembly compatible and improving both characteristics and reduction of indoor noise with good balance. <P>SOLUTION: In the pneumatic tire 1 rim-assembled to a wheel in which a connection position of a disk part 8 relative to a rim 7 is offset from a rim width center to an outer side of the vehicle, thickness in a tire width direction from a heel side side surface of bead cores 4, 4 at bead parts 2, 2 to an inner surface of rim flanges 7a, 7a is made at the vehicle outer side and the vehicle inner side in the state that the bead parts 2, 2 are rim-assembled. Thickness Wo at the vehicle outer side is made smaller than thickness Wi at the vehicle inner side. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire. More specifically, the present invention achieves both the fitting property when assembling a rim of a tire to be mounted on an offset type wheel and the resistance to rim removal after assembling the rim. The present invention relates to a pneumatic tire that improves the reduction in a well-balanced manner.

  In general, the operation of assembling a pneumatic tire on the wheel mounted on the vehicle is to place the bead portion on the inner side of the vehicle on the bead seat on the inner side of the vehicle, then drop the bead portion on the outer side of the vehicle into the well portion of the rim, and then While filling the internal pressure, the rim hump is overcome and seated on the bead seat outside the vehicle.

  However, it is known that the fitting property at the time of assembling the rim and the anti-rim detaching property after assembling the rim are in a trade-off relationship, and that the anti-rim detaching property is lowered when the fitting property is increased. Conventionally, many proposals have been made as countermeasures for satisfying this contradictory relationship (see, for example, Patent Document 1). However, none of these proposals was satisfactory as a combination of fitting properties at the time of rim assembly and resistance to rim removal after rim assembly.

  According to the inventor's research, the fitting property at the time of assembling the rim and the resistance to rim removal after assembling the rim are shown in FIG. 3 from the heel side surface of the bead core C in the bead portion B to the bead portion outer wall surface. Depending on the thickness W in the tire width direction, if the bead core C embedded in the bead portion B is positioned on the heel side and the heel side thickness W is reduced, it is necessary to overcome the hump H of the rim R. Since the amount of expansion of the bead core C and the amount of rubber deformation on the heel side can be kept small, the fitting property at the time of assembling the rim can be improved, and at the same time, the rim flange RF between the bead core C and the bead core C can be improved. It has been found that the rim detachment resistance is improved because the distance of the rim is reduced.

Conventionally, the bead core embedded in the bead portion is arranged at a substantially central position in the tire width direction of the bead portion from the viewpoint of emphasizing tire uniformity (conity), and the tire width extending from the left and right side surfaces of the bead core to the bead portion wall surface. It has been suggested that the wall thickness in the direction should be approximately equal on the left and right. However, in a wheel in which the connection position of the disk part with respect to the rim is offset to the outside of the vehicle, the rigidity of the rim is different between the inside and outside of the vehicle with the connection position of the disk part as the center. In the tire assembled on the rim, the bead portion located on the inner side of the vehicle receives greater vibration than the bead portion located on the outer side. Therefore, a tire in which the thickness in the tire width direction from the heel side surface of the bead core to the inner surface of the rim flange is the same in the left and right bead portions, the balance of vibration in the left and right bead portions is lost, and vehicle interior noise is likely to occur. There was a problem.
Japanese Patent Laid-Open No. 2002-2236

  The object of the present invention is to solve the above-mentioned problems in the background, and at the same time, it is possible to achieve both the fitting property at the time of rim assembly and the rim removal resistance after the rim assembly in a tire mounted on an offset type wheel. It is an object of the present invention to provide a pneumatic tire that improves both characteristics and the reduction of vehicle interior noise in a well-balanced manner.

  In order to achieve the above object, the pneumatic tire according to the present invention is a pneumatic tire in which a pair of left and right bead portions are assembled on a wheel whose connecting position of the disc portion to the rim is offset from the center of the rim to the outside of the vehicle. In the state where the bead portion is assembled to the rim, the thickness in the tire width direction from the heel side surface of the bead core to the rim flange inner surface in the bead portion is different between the vehicle outer side and the vehicle inner side. Is made smaller than the wall thickness Wi on the inside of the vehicle.

Furthermore, in the structure mentioned above, it is preferable to comprise as described in (1)-(4) below.
(1) The ratio Wo / Wi between the wall thickness Wo and the wall thickness Wi is set to 0.5 or more and less than 0.8.
(2) The wall thickness Wo is less than 4.0 mm, and the wall thickness Wi is 5.0 mm or more.
(3) The wall thickness Wo is set to 2.5 mm or more, and the wall thickness Wi is set to less than 6.5 mm.
(4) A rubber composition having a tan δ at 60 ° C. of 0.25 or more is disposed at a position corresponding to the thickness Wi.

  According to the present invention, the thickness in the tire width direction from the heel side surface of the bead core to the rim flange inner surface in the bead portion is formed thinner than the bead portion on the vehicle inner side in the bead portion on the vehicle outer side. When the bead portion on the outside of the vehicle gets over the hump of the rim, the bead core stretch amount and the rubber deformation amount on the heel side can be kept small, and the fitting property of the bead portion can be improved, and at the same time The distance between the bead core and the rim flange in the assembled tire is narrowed, and the rim detachment resistance can be improved.

  Further, since the wall thickness at the bead portion inside the vehicle is made thicker than the thickness at the bead portion outside the vehicle, the increase in vibration accompanying the decrease in the rim rigidity inside the vehicle due to the offset type rim is reduced. The rubber on the heel side in the bead portion inside the vehicle that is formed thickly absorbs efficiently, and the in-vehicle noise can be reduced.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view showing a state in which a pneumatic tire according to an embodiment of the present invention is mounted on an offset rim, and FIG. 2 is an enlarged cross-sectional view of a main part shown by omitting a part of FIG.

  In FIG. 1, a pneumatic tire 1 has a carcass layer 3 mounted between a pair of left and right bead portions 2, 2, and this carcass layer 3 is placed inside the tire around bead cores 4, 4 embedded in the bead portions 2, 2. The belt layers 6 and 6 are disposed on the outer peripheral side of the carcass layer 3 of the tread portion 5. In the pneumatic tire 1, the pair of left and right bead portions 2, 2 are mounted on a wheel in which the connecting position of the disk portion 8 with respect to the rim 7 is offset from the rim width center to the vehicle outer side.

  As shown in FIG. 2, the pneumatic tire 1 is in a state where the left and right bead portions 2, 2 are assembled to each other, from the side surfaces of the bead cores 4, 4 on the heel side of the bead portions 2, 2 to the inner surfaces of the rim flanges 7 a, 7 a. The thickness in the tire width direction is different between the vehicle outer side and the vehicle inner side, and the wall thickness Wo on the vehicle outer side is made smaller than the wall thickness Wi on the vehicle inner side (Wo <Wi).

  Thus, by forming the wall thickness Wo in the bead portion 2 on the vehicle outer side thinner than the wall thickness Wi on the bead portion 2 on the vehicle inner side, the bead portion 2 on the vehicle outer side can remove the hump 7b of the rim 7 when the rim is assembled. The amount of elongation of the bead core 4 and the amount of rubber deformation on the heel side when climbing over can be suppressed, and the fitability of the bead portion 2 can be improved, and at the same time, the bead core 4 and the rim flange in the tire after rim assembly. The distance to 7a is narrowed, and the rim detachment resistance can be improved.

  Furthermore, the thickness Wi of the bead portion 2 on the vehicle inner side is made thicker than the wall thickness Wo on the bead portion 2 on the vehicle outer side, thereby reducing the rigidity of the rim 7 on the vehicle inner side due to the offset type rim 7. The accompanying increase in vibration can be absorbed by the rubber on the heel side of the thick bead portion 2 on the vehicle inner side to reduce the vehicle interior noise.

  In the present invention, the ratio Wo / Wi between the wall thickness Wo at the bead portion 2 on the vehicle outer side and the wall thickness Wi at the bead portion on the vehicle inner side may be adjusted to be 0.5 or more and less than 0.9. As a result, the fitting property of the bead portion 2 with the rim 7 and the rim detachment resistance can be balanced with each other, and at the same time, both of these characteristics and reduction of in-vehicle noise can be improved in a balanced manner. In addition, if Wo / Wi mentioned above deviates from the range mentioned above, it will become a cause by which tire uniformity (conity) deteriorates.

  That is, in the pneumatic tire 1 of the present invention, the thickness Wo is made thin without changing the thickness Wi, thereby improving the fitting property and the rim detachment resistance while maintaining the effect of reducing the in-vehicle noise. Can be made. Further, by forming the wall thickness Wi thick without changing the wall thickness Wo, it is possible to reduce the in-vehicle noise while maintaining the fitting property and the rim removal resistance. And, by forming the wall thickness Wo to be thin and the wall thickness Wi to be thick, it is possible to achieve a high level of compatibility between fitability and rim detachment resistance and at the same time to reduce vehicle interior noise at a high level. Can do.

  Therefore, by appropriately setting the above-mentioned wall thickness Wi and wall thickness Wo according to the type and size of the tire, it is possible to improve in a well-balanced manner with a good balance between fitability, rim detachment resistance and vehicle interior noise reduction effects. can do.

  In the present invention, it is more preferable that the vehicle outer thickness Wo is less than 4.0 mm, preferably less than 3.5 mm, and the vehicle inner thickness Wi is 5.0 mm or more, preferably 5.3 mm or more. . As a result, it is possible to reliably achieve both fitting properties when assembling the rim and resistance to rim removal after assembling the rim, and reliably reduce in-vehicle noise.

  Note that the thickness in the tire width direction from the side surface of the bead core 4 to the inner surface of the rim flange 7a on the heel side of the bead portion 2 described above is the tire rotation axis direction (tire of the tire) passing through the outermost end of the bead core 4 in the tire width direction. The distance between the outermost end of the bead core 4 and the inner surface of the rim flange 7a in the width direction).

  In the case described above, more preferably, the lower limit value of the wall thickness Wo in the bead portion 2 outside the vehicle is 2.5 mm or more, preferably 2.8 mm or more, and the upper limit value of the wall thickness Wi in the bead portion 2 inside the vehicle is set as the upper limit value. It may be less than 6.5 mm, preferably less than 6.0 mm. This is because when the wall thickness Wo is less than 2.5 mm, the durability of the bead portion 2 is lowered, and when the wall thickness Wi is 6.5 mm or more, the tire uniformity (conity) is deteriorated.

  The pneumatic tire 1 of the present invention is configured so that the thickness Wi in the bead portion 2 on the vehicle inner side is thicker than the wall thickness Wo on the bead portion 2 on the vehicle outer side, thereby reducing in-vehicle noise caused by the offset type rim. More preferably, tan δ at 60 ° C. is 0.25 or more at a position from the heel side surface of the bead core 7 to the inner surface of the rim flange 7a in the bead portion 2 inside the vehicle corresponding to the wall thickness Wi. Preferably, a rubber composition of 0.33 or less is disposed. Thereby, in-vehicle noise can be reduced more efficiently.

  The tan δ of the rubber composition described above is a value measured using a viscoelastic spectrometer (manufactured by Iwamoto Seisakusho) under the conditions of a frequency of 20 Hz, an initial strain of 10%, a dynamic strain of ± 2%, and a temperature of 60 ° C. Say.

  As described above, in the pneumatic tire 1 of the present invention, the thickness in the tire width direction from the heel side surface of the bead core to the inner surface of the rim flange in the bead portion 2 in the state where the bead portion 2 is assembled on the wheel is outside the vehicle. In order to reduce the noise in the vehicle while improving the fitting property when assembling the rim and the anti-rim removal property after assembling the rim, by forming it thicker than the outside of the vehicle inside the vehicle. Therefore, since it has an excellent effect while having a simple configuration, it can be widely applied as a tire for passenger cars to be mounted on an offset type wheel.

  The tire size is 215 / 60R16, the tire structure is FIG. 1, and the wall thicknesses Wo and Wi shown in FIG. 2 are different as shown in Table 1, respectively. Conventional tires (conventional examples) and tires of the present invention (Examples 1 to 7) ) And comparative tires (Comparative Examples 1 and 2).

  When these 10 types of tires are mounted on the offset type rim (size: 16 × 6.5J) shown in FIGS. 1 and 2, the fitability, rim detachment resistance, and noise resistance are evaluated by the following methods. The results are also shown in Table 1.

[Matchability]
The air pressure (kPa) when each tire was completely fitted to the offset rim shown in FIG. 1 was measured, and the result is shown as “fitting pressure” in Table 1. The smaller this value is, the better the fitting property is.

[Rim resistance]
Each tire was fitted to the offset rim shown in FIG. 1, and the bead unseat value (kN) was measured in accordance with JIS D4230. The result is shown as “BUS value” in Table 1. The larger this value, the better the rim detachment resistance.

[Noise]
Each tire is fitted to the offset rim shown in FIG. 1, filled with air pressure 210 kPa, mounted on a 1.5 liter FF vehicle, and then run on a test course partially including uneven surfaces at an average speed of 50 km / h. Then, sensory evaluation of vehicle interior noise was conducted by five trained test drivers. The evaluation was performed by a five-point method in which three conventional examples were used, and the three evaluation points excluding the highest and lowest points were averaged and listed as “RN characteristics” in Table 1. Larger values indicate better noise performance.

  From Table 1, it can be seen that the tire of the present invention is improved in fitting property, rim detachment resistance and noise resistance in a well-balanced manner as compared with the conventional tire.

It is sectional drawing which shows the state which mounted | wore the offset rim with the pneumatic tire by embodiment of this invention. It is an expanded sectional view of the principal part which abbreviate | omits a part of FIG. It is sectional drawing of the principal part for demonstrating the influence which the bead structure of a tire has on fitting property.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Bead part 4 Bead core 7 Rim 7a Rim flange 8 Disc part Wo, Wi Thickness

Claims (5)

In a pneumatic tire in which a pair of left and right bead parts are assembled on a wheel whose connecting position of the disk part to the rim is offset from the center of the rim width to the outside of the vehicle,
With the bead portion rim assembled to the wheel, the thickness of the bead core in the tire width direction from the heel side surface of the bead core to the rim flange inner surface is different between the vehicle outer side and the vehicle inner side, A pneumatic tire having a thickness Wo smaller than the wall thickness Wi on the inside of the vehicle.   The pneumatic tire according to claim 1, wherein a ratio Wo / Wi of the wall thickness Wo to the wall thickness Wi is set to 0.5 or more and less than 0.8.   The pneumatic tire according to claim 1 or 2, wherein the wall thickness Wo is less than 4.0 mm, and the wall thickness Wi is 5.0 mm or more.   The pneumatic tire according to claim 1, 2 or 3, wherein the wall thickness Wo is 2.5 mm or more and the wall thickness Wi is less than 6.5 mm.   The pneumatic tire according to claim 1, 2, 3 or 4, wherein a rubber composition having a tan δ at 60 ° C of 0.25 or more is disposed at a position corresponding to the thickness Wi.

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