JPH10244815A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To damp an impact on a rim flange to reduce damage thereon when a tire goes over a large projection. SOLUTION: An annular rim guard 18 projecting outside in the direction of rotational axis of a tire and continuously extending in the peripheral direction of the tire is formed on the bead part 14 of a pneumatic tire 10. A plurality of impact damping grooves 20 extending along a rim flange 8A side substantially in the radial direction are formed on the rim guard 18 along the peripheral direction of the tire. When the tire goes over a projection like a curbstone, the tire is deformed to the limit and the rim guard 18 contacts completely the rim flange 8A and an external force applied by the road is transmitted to the rim flange 8A via the rim guard 18, but the impact damping grooves 20 damp the impact applied on the rim flange 8A to reduce damage on the rim flange 8A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire having a bead portion having an annular rim guard protruding outward in the tire rotation axis direction.

[0002]

2. Description of the Related Art In order to protect a wheel from being damaged by contact with a road curb or the like, there is a vehicle equipped with a rim guard that is continuous in a circumferential direction on a tire side.

[0003]

However, in the case of, for example, climbing over a curb or a large protrusion on a road at a speed of 30 km / h or more, a tire having a low tire height (for example, a super-flat tire having a rim diameter of 17 inches or more, etc.) is required. In the case of a tire with a height of 110 mm or less, the impact may not be absorbed by the deflection of the tire alone. Often.

The present invention has been made in consideration of the above circumstances, and has as its object to provide a pneumatic tire that can reduce the impact on a rim flange when riding over a large protrusion and reduce damage to the rim flange.

[0005]

According to the present invention, there is provided a pneumatic tire having a bead portion provided with an annular rim guard which protrudes outward in the tire rotation axis direction and is continuous in the tire circumferential direction. Is characterized in that a plurality of impact relaxation grooves extending substantially in the radial direction on the rim flange side are formed along the tire circumferential direction.

Next, the operation of the pneumatic tire according to the first aspect will be described. When climbing over a large protrusion such as a curb, when the tire bends to the limit, the rim guard comes into full contact with the rim flange, and the road surface input is transmitted to the rim flange via the rim guard.

Since the impact relief groove is formed on the side of the rim guard that comes into contact with the rim flange, the impact applied to the rim flange can be reduced, and damage to the rim flange can be reduced.

The present invention is particularly effective for a super-flat tire, for example, a tire having a height of 110 mm or less.

According to a second aspect of the present invention, in the pneumatic tire according to the first aspect, the impact relaxation groove has a groove width of 0.5 to 2.0 mm and an interval in the tire circumferential direction of 1.0 to 2.0 mm. 4.
0 mm, and the area of the side wall surface of the impact relaxation groove is 30 to 80% of the sectional area of the rim guard.

Next, the operation of the pneumatic tire according to claim 2 will be described. In the pneumatic tire according to claim 2,
The groove width of the shock absorbing groove is 0.5 to 2.0 mm, the interval in the tire circumferential direction is 1.0 to 4.0 mm, and the area of the groove side wall surface of the shock absorbing groove is 30 to 80% of the cross-sectional area of the rim guard. Therefore, the rigidity of the rim guard can be kept optimal, and there is no problem in tire production.

If the groove width of the impact relaxation groove is less than 0.5 mm, the rigidity of the blade (thin metal plate) of the mold forming the impact relaxation groove becomes low, causing a problem that the blade is easily bent. On the other hand, when the groove width of the shock absorbing groove exceeds 2.0 mm, the rigidity of the rim guard is excessively reduced, and the rim guard is not useful as an original rim guard.

When the distance between the shock absorbing grooves in the tire circumferential direction is 1.0
When the diameter is less than mm, the portion between the impact relaxation grooves becomes too thin, and may be chipped when removed from the mold, and the rigidity of the rim guard may be too low. on the other hand,
If the distance between the impact relaxation grooves in the tire circumferential direction exceeds 4.0 mm, the rigidity of the rim guard cannot be reduced,
Insufficient shock absorption.

If the cross-sectional area of the rim guard is less than 30% of the area of the side wall surface of the shock absorbing groove, the rigidity of the rim guard cannot be reduced, and the shock absorbing property becomes insufficient. On the other hand, if the cross-sectional area of the rim guard with respect to the area of the groove side wall surface of the impact relaxation groove exceeds 80%, the rigidity of the rim guard is too low, and the rim guard is not useful as an original rim guard.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the pneumatic tire of the present invention will be described with reference to FIG.

As shown in FIG. 1A, the pneumatic tire of this embodiment mounted on the rim 8 (tire size: 23
The 5/40 ZR 18) 10 includes a carcass 16 whose both ends are wound around a pair of left and right bead cores 12 (only one is shown in FIG. 1A) and moored to the bead portion 14.

The bead portion 14 is integrally provided with an annular rim guard 18 which protrudes outward in the tire rotation axis direction and is continuous in the tire circumferential direction.

The rim guard 18 has a radially outer side surface 18B and a radially inner side surface 18C corresponding to the rim flange 8A of the rim 8 formed in an arc shape.

The side surface 18C is formed so that the distance from the rim flange 8A gradually increases toward the outside in the tire rotation axis direction.

On the tire rotation axis side of the rim guard, a plurality of impact relaxation grooves 20 extending substantially along the tire radial direction are formed along the tire circumferential direction.

The impact relaxation groove 20 has a groove width t of 0.5-2.
Within the range of 0 mm, the interval L in the tire circumferential direction is 1.0 to 4.0.
It is preferably within the range of mm. Further, the area B of the groove side wall surface of the shock absorbing groove 20 when the cross section is formed in parallel with the tire rotation axis direction (hatched portion rising to the right in FIG. 1B) is 30 to 80 of the cross sectional area A of the rim guard 18. %. Here, the cross-sectional area A of the rim guard 18
Is a portion outside the outer contour (the imaginary line in FIG. 1) of the bead portion 14 where the rim guard 18 is not provided (FIG. 1B)
(The shaded area rising to the left).

In this embodiment, the top 1 of the rim guard 18 is
The width W of 8A is 5 mm, the height H measured from the outer contour of the bead portion 14 is 6 mm, the groove width t is 1.0 mm, the interval L is 2.5 mm,
The ratio of the area B of the groove side wall surface of the impact relaxation groove 20 to the cross-sectional area A of the rim guard 18 is set to 50%.

Next, the operation of the present embodiment will be described. When the vehicle equipped with the pneumatic tire 10 gets over a curb or a large protrusion on the road and completely bends, the input of the road surface may be transmitted to the rim flange 8A via the rim guard 18. Since the rigidity of the rim guard 18 on the rim flange 8A side is reduced by the impact relaxation groove 20, the impact input to the rim flange 8A is reduced, and damage to the rim flange 8A can be reduced.

The shock absorbing groove 20 extends linearly along the tire radial direction, but may be slightly inclined with respect to the tire radial direction (within 30 degrees) or may be slightly bent. good. [Test Example] In order to confirm the effect of the present embodiment, a conventional tire and an example tire to which the present invention was applied were prepared.
A test was performed to get over the protrusion. (Test method) A European-made passenger car equipped with test tires was run, and rod-shaped projections (height: 80 mm, width: 1) installed on the road surface
(00 mm) at a constant speed from a direction of 45 degrees to get over the protrusion. Starting at a speed of 10 km / h, the rider repeatedly passed over while increasing the speed by 5 km / h until the rim flange was deformed.

The example tire is the tire of the above-described embodiment, and the conventional tire is a tire in which an impact relief groove is not formed in the rim guard.

As a result of the test, the speed when the rim flange was deformed was as shown in Table 1 below.

[0026]

[Table 1] As shown in Table 1 above, it can be seen that the example tire to which the present invention is applied has a higher speed at which the rim flange is deformed than the conventional tire, and is excellent in absorbing the impact input to the rim flange. .

[0027]

As described above, in the pneumatic tire of the present invention, a plurality of impact relief grooves extending substantially along the radial direction are formed on the rim flange side of the rim guard along the tire circumferential direction. This has an excellent effect of reducing the impact on the rim flange when riding over the projection and reducing damage to the rim flange.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view of a bead portion of a pneumatic tire according to an embodiment of the present invention, and FIG. 1B illustrates a cross-sectional area of a rim guard and an area of a side wall surface of a shock absorbing groove 20. FIG.

[Explanation of symbols]

 Reference Signs List 10 Pneumatic tire 14 Bead part 18 Rim guard 20 Shock relief groove

Claims (2)

[Claims] 1. A pneumatic tire having a bead portion provided with an annular rim guard continuous in a tire circumferential direction protruding outward in a tire rotation axis direction, wherein the rim guard has a substantially radial direction on a rim flange side. A pneumatic tire, wherein a plurality of impact relief grooves extending along the tire circumferential direction are formed. 2. The shock-absorbing groove has a groove width of 0.5-2.
0mm, the interval in the tire circumferential direction is 1.0 to 4.0mm,
The area of the groove side wall surface of the impact relaxation groove is 30 to 80% of the cross-sectional area of the rim guard.
A pneumatic tire according to claim 1.