JP2005262977A - Pneumatic tires for passenger cars that can be mounted on asymmetric flange-shaped rims - Google Patents

Abstract

Provided is a pneumatic tire for a passenger car that can be attached to a rim having an asymmetric flange shape having a larger rim flange diameter on one side, and can suitably suppress uneven wear of a shoulder portion. about.
A pneumatic tire according to the present invention includes a bulging portion 11 on at least one side of a sidewall portion 2, and a vertex T of the bulging portion 11 has a height of 55 mm or more based on a nominal diameter NR. The height of the sidewall portion 2 from the contour 2a is 3 mm or more, the contour extension line 14 of the radius of curvature Rt appearing on the surface of the tread portion 4 from the outermost point of the tire, and the surface of the sidewall portion 2 The distance in the tire radial direction to the intersection A with the contour extension line 12 of the radius of curvature Rsi that appears in P is the P drop amount, the P drop amount outside the vehicle is Po, the P drop amount inside the vehicle is Pi, and the tread width is TW. In this case, 0.0015 ≦ (Po−Pi) /TW≦0.0045 is satisfied.
[Selection] Figure 3

Description

  The present invention relates to a pneumatic tire for a passenger car that can be suitably used for a rim having a larger rim flange diameter than before.

  In recent years, pneumatic tires for passenger cars have a tendency not only to improve tire performance such as durability and steering stability, but also to enhance fashionability with emphasis on design. Among them, a wheel in which a tire having a small flatness is assembled on a rim (wheel) has an image of a sports tire, and is particularly attracting attention. However, a tire with a small flatness has a drawback in that the load capacity decreases as the tire internal volume decreases. For this reason, it has been considered to increase the rim flange diameter as a method for improving the fashionability of the wheel as described above without reducing the flatness of the pneumatic tire. However, increasing the rim flange diameter on both sides makes it very difficult to fit pneumatic tires and deteriorates the rim assembly, so an asymmetric flange-shaped rim with only a large rim flange diameter on one side was developed. .

  However, when the rim having the asymmetric flange shape is used, the tire deflection is suppressed on the side where the rim flange diameter is formed large, so that the ground contact pressure of the shoulder portion becomes higher than that on the opposite side, and uneven wear occurs. Turned out to be.

Conventionally, in order to suppress such uneven wear, for example, a tire disclosed in Patent Document 1 below has been proposed. This tire has an asymmetric profile in which the outer diameter and thickness of the tire on the side with significant wear are larger than those on the opposite side, and the rigidity on the side with significant wear is increased to suppress deflection. However, when the asymmetric flange-shaped rim is used, the side with significant wear is the side where the rim flange diameter is formed large. Therefore, setting the tire outer diameter and wall thickness on that side large This is contrary to the purpose of the rim to enhance fashionability. Therefore, the tire of the following Patent Document 1 is not applicable to a tire mounted on the rim having the asymmetric flange shape.
JP-A-8-230408

  Accordingly, an object of the present invention is a pneumatic tire for a passenger car that can be mounted on an asymmetric flange-shaped rim having a larger rim flange diameter on one side than the conventional one, and is capable of suitably suppressing uneven wear of a shoulder portion. The purpose is to provide tires.

  The above object can be achieved by the present invention as described below. That is, the pneumatic tire for a passenger car of the present invention includes a pair of annular bead portions, sidewall portions extending from the bead portions to the outer peripheral side, and shoulder portions at the outer peripheral side ends of the sidewall portions. A tread portion that is continuous, and an annular bulging portion that has an inner peripheral side surface capable of suppressing deformation of the sidewall portion by contacting an outer circumferential curved surface of the rim flange on at least one side of the sidewall portion; The bulging part has a vertex at a height of 55 mm or more with reference to the nominal diameter, the height from the contour of the radius of curvature appearing on the surface of the sidewall part at the vertex is 3 mm or more, and the outermost part of the tire The radial distance between the radial point and the intersection of the contour extension line of the radius of curvature that appears on the surface of the tread portion and the contour extension line of the radius of curvature that appears on the surface of the sidewall portion When the amount of P fall is P, the amount of P fall on the outer side of the vehicle when the tire is mounted is Po, the amount of P fall on the inner side of the vehicle is Pi, and the tread width of the tread portion is TW. 0015 ≦ (Po−Pi) /TW≦0.0045 is satisfied.

  According to the structure of the present invention, the amount of P fall on the vehicle outer side (the side on which the rim flange diameter is formed larger) when the tire is mounted is larger than the amount of P fall on the vehicle inner side. The amount of deflection required for grounding the shoulder portion is relatively large. As a result, the contact pressure of the shoulder portion located on the vehicle outer side can be reduced, and uneven contact pressure can be eliminated and uneven wear of the shoulder portion can be suitably suppressed. Further, since the P drop amount is set within a predetermined range in relation to the tread width, the contact pressure can be made uniform in accordance with various tire sizes.

  Here, the contour extension line of the radius of curvature appearing on the surface means an arc extending the surface with the curvature of the surface. Furthermore, the tread width is the contour extension of the radius of curvature that appears on the surface of the sidewall portion, and the contour extension of the radius of curvature that appears on the surface of the tread portion that continues to the outer peripheral side end of the sidewall portion via the shoulder portion. It is defined by the tire axial distance between the intersections with the line.

  Further, the apex of the bulging portion provided on at least one side of the sidewall portion has a height of 55 mm or more based on the nominal diameter, and the height from the contour of the curvature radius appearing on the surface of the sidewall portion is 3 mm. Because of the above, rim assembly is easy even for a rim having a larger rim flange diameter than before, and the protection function of the rim flange is improved. In addition, since the bulging part has an inner peripheral side surface that can abut against the outer peripheral curved surface of the rim flange and suppress the deformation of the sidewall part, contact with the rim flange and wear due to the deformation of the sidewall part are effective. Can be suppressed. Furthermore, the bulging part which has the said inner peripheral side surface can suppress the deformation | transformation of a side wall part, and can improve the exercise | movement performance of a tire.

  In the above, what satisfies 0.0400 <= Pi / TW <= 0.0500 is preferable.

  With the above configuration, the amount of P drop on the vehicle inner side when the tire is mounted is substantially the same as that of the vehicle, so that the steering stability is ensured and the above-described deviation is set by setting the P drop amount on the vehicle outer side. The effect of suppressing wear can be achieved relatively easily.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a tire meridian cross-sectional view showing an example of a pneumatic tire for passenger cars of the present invention. FIG. 2 is an enlarged view of a main part showing a main part near a sidewall part of the tire according to FIG.

  As shown in FIG. 1, the pneumatic tire of the present invention has a pair of annular bead parts 1, a sidewall part 2 extending from the bead part 1 to the outer peripheral side, and shoulders at the outer peripheral side ends of the sidewall part 2. And a tread portion 4 connected via the portion 3. This structure is the same as a general tire, and the present invention can be applied to any tire having the structure. Moreover, in such a pneumatic tire, it is not always necessary to have a radial tire structure, and a bias tire or a carcass layer 5 with a partially inclined cord may be used.

  The bead portion 1 is provided with a bead 1a and a bead filler 1b, which are bead wire bundling bodies surrounded by the carcass layer 5, and the end portion of the carcass layer 5 is rewound and locked by the bead 1a. The tire is firmly fitted onto the rim 20 in a state where the space between the bead portions 1 is reinforced by the carcass layer 5. Rubber layers are formed on both sides of the carcass layer 5, and in the tubeless tire, an inner liner layer is formed as the innermost layer. In addition, a belt layer 6 that reinforces by the effect of warping is arranged on the outer peripheral side of the carcass layer 5, and a tread pattern is formed on the outer peripheral surface of the carcass layer 5 by tread rubber. In the present invention, the shape of the tread pattern and the rubber hardness of the members constituting the tire are not particularly limited.

  Examples of the raw rubber for the rubber layer include natural rubber, styrene butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), and butyl rubber (IIR). These rubbers are reinforced with fillers such as carbon black and silica, and a vulcanizing agent, a vulcanization accelerator, a plasticizer, an antiaging agent, and the like are appropriately blended.

  Further, a steel wire or the like is used as the bead wire, and steel, organic fibers such as polyester, rayon, nylon, and aramid are used as the constituent material of the carcass layer 5 and the belt layer 6. These materials are usually subjected to surface treatment, adhesion treatment or the like in order to improve adhesion to rubber.

  In the present embodiment, the intersection between the tire equator line C and the surface of the tread portion 4 is the tire outermost point M that is the outermost diameter position of the tire, and the tire profile of the present invention is the outermost tire as described later. Asymmetric on both sides of the diameter point M. In the present invention, the position of the tire outermost diameter point M is not limited to that on the tire equator line C.

  The pneumatic tire of the present invention includes an annular bulging portion 11 that functions as a rim protector on at least one side wall portion 2. The bulging portion 11 has an inner peripheral side surface 11 a that abuts against the outer peripheral curved surface 21 a of the rim flange 21 and can suppress deformation of the sidewall portion 2. The inner peripheral side surface 11a of the bulging part 11 may be separated from the outer peripheral side curved surface 21a of the rim flange 21, and when the tire deforms during traveling, the inner peripheral side surface 11a of the bulging part 11 is on the outer peripheral side. It is only necessary that the deformation of the sidewall portion 2 can be suppressed by contacting the curved surface 21a. In the present embodiment, an example is shown in which the inner peripheral side surface 11a of the bulging portion 11 is always in contact with the outer peripheral curved surface 21a.

  The bulging portion 11 has a vertex T at a height R1 of 55 mm or more with reference to the nominal diameter NR. The height H1 of the vertex T is 3 mm or more, preferably 10 to 15 mm. Here, the height H1 means the height from the contour 2a of the radius of curvature Rsi that appears on the surface of the sidewall portion 2 in the tire meridian cross section. The hardness of the rubber constituting the bulging portion 11 is preferably 45 to 85 ° in terms of JIS A hardness. At that time, rubber may be reinforced with short fibers or reinforced with long fibers.

  The position of the apex T of the bulging portion 11 is preferably 0 to 4 mm higher than the height HR of the rim flange 21 of the rim 20. Thereby, while the deformation suppression effect of the side wall part 2 is acquired suitably, it can prevent that foreign materials, such as sand, mix between a rim | rim and a tire. At that time, the height based on the nominal diameter NR at the position of the apex T of the bulging portion 11 is preferably 41 to 61% with respect to the tire cross-section height H2. Thereby, since it becomes the external appearance equivalent to a tire with a flat rate of 20 to 30%, an image of a sports tire is generated, and fashionability is also high. Moreover, it is preferable that the position of the apex T of the bulging part 11 is arranged on the tire outer peripheral side from the position of the tire maximum width.

  3 is an enlarged view of the main part showing the main part near the shoulder part of the tire according to FIG. 1. FIG. 3 (a) shows the vicinity of the shoulder part located on the outer side of the vehicle when the tire is mounted, and FIG. Similarly, the vicinity of the shoulder portion located inside the vehicle is shown.

  As shown in FIG. 3, in the shoulder portion 3 located on both sides of the tread portion 4, the contour 3 a of the curvature radius Rsh that appears on the surface is the contour 4 a of the curvature radius Rt that appears on the surface of the tread portion 4. Each is inscribed in the contour 2a of the curvature radius Rsi that appears on the surface of the wall portion 2. Here, the contour extension line 12 indicated by a broken line is an arc obtained by extending the contour 2a with the curvature of the curvature radius Rsi, and the contour extension line 14 also indicated by the broken line extends the contour 4a with the curvature of the curvature radius Rt. It is an arc. The P drop amount is defined as the distance in the tire radial direction from the tire outermost point M (not shown in FIG. 3) to the intersection A of the contour extension line 12 and the contour extension line 14. In addition, the curvature radii Rsi, Rsh, and Rt that respectively appear on the surfaces of the sidewall portion 2, the shoulder portion 3, and the tread portion 4 are not particularly limited.

  In the pneumatic tire of the present invention, when the tire is attached, the amount of P fall on the vehicle outer side is Po, the amount of P fall on the vehicle inner side is Pi, and the tire axial distance between the intersections A is the tread width TW. 0.0015 ≦ (Po−Pi) /TW≦0.0045, more preferably 0.0025 ≦ (Po−Pi) /TW≦0.0035. As a result, the amount of deflection required for the ground contact of the shoulder portion located outside the vehicle becomes relatively large, and the ground contact pressure outside the vehicle can be reduced. As a result, uneven contact pressure can be eliminated and uneven wear of the shoulder portion 3 can be suitably suppressed.

  When (Po−Pi) / TW is less than 0.0015, the effect of reducing the contact pressure of the shoulder portion 3 located outside the vehicle is small, and the effect of suppressing the uneven wear of the shoulder portion 3 is small. If (Po−Pi) / TW exceeds 0.0045, the difference between the P drop amount Po and the P drop amount Pi becomes large, and the contact pressure of the shoulder portion 3 located outside the vehicle becomes too low. In addition, the contact pressure is not uniform, and the tire profile is greatly different on both sides of the outermost diameter point M, so that the steering stability is deteriorated.

  In the pneumatic tire of the present invention, it is preferable that the P drop amount Pi with respect to the tread width TW satisfies 0.0400 ≦ Pi / TW ≦ 0.0500. With the above configuration, the P drop amount Pi becomes substantially conventional, so that the steering stability is ensured, and the effect of suppressing the above-described uneven wear can be achieved relatively easily by setting the P drop amount Po.

  The pneumatic tire according to the present invention has an asymmetric profile as described above, and the tire mounting direction or rotation direction is designated. The pneumatic tire can be easily manufactured by vulcanization molding using a mold or the like corresponding to the asymmetric profile.

[Other Embodiments]
(1) In the above-described embodiment, an example in which one curvature radius appears on the surface of the tread portion 4 is shown. However, the pneumatic tire of the present invention is not limited to this, for example, on both sides of the tire outermost diameter point M. A plurality of curvature radii may appear on the surface of the tread portion 4. At that time, the intersection A is defined as an intersection between the contour extension line 12 of the sidewall portion 2 and the contour extension line of the tread portion connected to the outer peripheral side end of the sidewall portion 2 via the shoulder portion 3.

  (2) In the above-described embodiment, an example in which the tire structure of the portion inscribed in the rim flange 21 outside the vehicle is the same as the conventional tire structure is shown. . For example, since the reinforcement around the bead 1a is performed by the rim flange 21, the hardness of the bead filler 1b may be reduced or the height thereof may be reduced. In order to reduce contact with the rim flange 21 and wear, a rubber layer having a JIS A hardness of 65 to 90 ° may be provided on the surface of the sidewall portion 2. Furthermore, it is good also as a structure which has arrange | positioned the reinforcement layer by the bead 1a around a steel cord or a nylon cord.

  (3) In the above-described embodiment, the example in which the cross-sectional shape of the bulging portion 11 is a substantially triangular shape has been described. However, the shape is not limited thereto, and may be a substantially trapezoidal shape, a substantially semicircular shape, a substantially crescent shape, or the like. In addition, the shape of the inner peripheral side surface 11a of the bulging portion 11 may be a shape that bulges outward from a straight line drawn from the apex T to the outer wall 2a of the sidewall portion 2, or may be a shape constricted to the inside. When the inner peripheral side surface 11a of the bulging portion 11 is constricted inward, the curvature radius PR is preferably 3 to 30 mm, more preferably 5 to 20 mm, from the fit to the outer peripheral side curved surface 21a of the rim flange 21. More preferred.

  Examples and the like specifically showing the configuration and effects of the present invention will be described below.

  In a prototype tire in which the tire size is 305 / 45R22 118V, tread width TW = 258 mm, and P drop amount Pi = 11.26 mm on the vehicle inner side when the tire is mounted, the P drop amount Po on the vehicle outer side is changed. The ground pressure distribution was measured for each. The contact pressure is measured by placing a prototype tire with an air pressure of 220 kPa on a plate under a load of 80% JATMA and using a detector provided on the plate to evaluate the contact pressure distribution. The tread portion was divided into three areas extending in the tire width direction. The three regions are shown as an S-OUT portion, a center portion, and an S-IN portion in order from the vehicle outer side (the side on which the rim flange diameter is formed larger) in a state where the tire is mounted on the rim. The ground pressure at the center portion is 100, and the ground pressure at the S-OUT portion and the S-IN portion is expressed as a ratio with the center portion.

表１の結果が示すように、従来例では、リムフランジ径が大きく形成された側においてタイヤのたわみが抑制されるため、Ｓ−ＯＵＴ部の接地圧がＳ−ＩＮ部よりも高くなり、接地圧が不均一となる。これにより、ショルダー部に偏摩耗が発生する。

As shown in the results of Table 1, in the conventional example, since the deflection of the tire is suppressed on the side where the rim flange diameter is formed large, the ground pressure of the S-OUT portion becomes higher than that of the S-IN portion, The pressure is uneven. Thereby, uneven wear occurs in the shoulder portion.

  On the other hand, in Examples 1 to 3, the P fall amount Po on the vehicle outer side when the tire is mounted is made larger than the P fall amount Pi on the vehicle inner side, so that the grounding of the shoulder portion located on the vehicle outer side is made. As a result, the amount of deflection required increases, and the ground pressure at the S-OUT portion decreases to make the ground pressure substantially uniform. Thereby, generation | occurrence | production of uneven wear can be suppressed.

  In Comparative Example 1, since the difference in the P drop amount between the vehicle outer side and the vehicle inner side is small, the effect of lowering the ground pressure at the S-OUT portion is small, and the ground pressure is not uniform. In Comparative Example 2, since the difference in the amount of P drop between the vehicle outer side and the vehicle inner side is large, the ground pressure at the S-OUT portion is too low, and the ground pressure is not uniform. In any case, the effect of suppressing the uneven wear of the shoulder portion is reduced. Moreover, in the case of the comparative example 2, since the tire profile is greatly different between the S-OUT part and the S-IN part, the steering stability is likely to deteriorate.

Tire meridian cross-sectional view showing an example of a pneumatic tire for passenger cars of the present invention FIG. 1 is an enlarged view of a main part showing a main part near a sidewall part of the tire according to FIG. Fig. 1 is an enlarged view of a main portion showing the vicinity of a shoulder portion of the tire according to Fig. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Bead part 2 Side wall part 2a The outline of the curvature radius which appeared on the surface of the side wall part 3 Shoulder part 3a The outline of the curvature radius which appeared on the surface of the shoulder part 4 Tread part 4a The outline of the curvature radius which appeared on the surface of the tread part DESCRIPTION OF SYMBOLS 11 Bulging part 11a Inner side surface of bulging part 12 Contour extension line of sidewall part 14 Contour extension line of tread part 20 Rim 21 Rim flange 21a Outer peripheral side curved surface A Intersection C Tire equator line H1 Top of bulging part Height NR Nominal diameter Pi P drop amount on the vehicle inner side Po P drop amount on the vehicle outer side Rsh Curvature radius appearing on the surface of the shoulder portion Rsi Curvature radius appearing on the surface of the sidewall portion Rt Radius of curvature that appeared on the surface T Top of the bulge TW Tread width

Claims (2)

A pair of annular bead portions, sidewall portions extending from the bead portions to the outer peripheral side, tread portions connected to outer peripheral side ends of the sidewall portions via shoulder portions, and at least one side of the sidewall portions And an annular bulging portion having an inner peripheral side surface capable of suppressing deformation of the sidewall portion by contacting the outer peripheral curved surface of the rim flange,
The bulge portion has a vertex at a height of 55 mm or more on the basis of the nominal diameter, and the height from the contour of the radius of curvature that appears on the surface of the sidewall portion of the vertex is 3 mm or more,
The distance in the tire radial direction from the outermost diameter point of the tire to the intersection of the contour extension line of the radius of curvature that appears on the surface of the tread portion and the contour extension line of the radius of curvature that appears on the surface of the sidewall portion is reduced by P Further, when the amount of P fall on the outer side of the vehicle when the tire is mounted is Po, the amount of P fall on the inner side of the vehicle is Pi, and the tread width of the tread portion is TW, 0.0015 ≦ A pneumatic tire for a passenger car that satisfies (Po-Pi) /TW≦0.0045. The pneumatic tire for passenger cars according to claim 1, wherein 0.0400 ≦ Pi / TW ≦ 0.0500 is satisfied.

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