JPH0769010A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To improve resistance against coming off from a rim while avoiding difficulty of rim assembling by forming many inclined ridges which fall down on the outside in the tire axial direction in relation to a normal to a rotation axis of the tire, on a surface of a bead base. CONSTITUTION:A rubber outer skin 52 which covers a carcass and folds back in the circumference of a bead core 20 is formed of a bead heel 54 which fits in a recessed section at a round corner of a rim, a bead base 56, and a bead tow 58. Many ridges consisting of inclined ridges 60 which fall down on the outside in the tire axial direction relative to an equatorial plane of the tire are arranged on a surface of the baed base 56. Consequently, it is possible to improve resistance against coming off from the rim while avoiding difficulty of rim assembling.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire which prevents the rim from coming off.

[0002]

2. Description of the Related Art A pneumatic tire is provided with a bead portion which tightly fits to a rim having an inclined bead seat, a rim flange and a rounded corner recess interposed therebetween. The bead portion is mainly composed of a bead core, a carcass whose ends are locked by folding back around the core, and a rubber outer cover that further covers the carcass. Fitted bead heel with rounded corners, bead base with side or side tightened by increasing the angle of inclination with respect to the tire rotation axis compared to the inclined bead seat of the rim, and the bead base and side A bead toe is formed by intersecting the inner wall of the lower part of the wall, and fits with the rim as described above.

During normal running, the tire does not come off the rim due to the filled internal pressure and the tightening margin of the bead base, but when the internal pressure decreases, the tightening becomes weak and the rim comes off easily. Various proposals have been made to improve the rim detachability.

Among the above proposals, there is a method of increasing the tightening force to the rim by decreasing the diameter of the bead core or increasing the cross-sectional area of the bead core, but in this case, it becomes difficult to assemble the tire on the rim. There was a problem that it would end up.

[0005]

Therefore, it is an object of the present invention to improve the rim detachment resistance while avoiding the difficulty of assembling the rim.

[0006]

SUMMARY OF THE INVENTION The present invention comprises a bead portion which fits tightly to a rim having an inclined bead seat, a rim flange and a rounded corner recess interposed between the bead portion and the rim flange. Consists of a bead core, a carcass that is locked by folding back around the core, and a rubber outer covering that covers these, and the rubber outer covering is a rounded convex bead heel that fits into the rounded rounded recess of the rim. A bead base formed by intersecting a bead base and an inner wall of a sidewall portion with a bead base having a tightening margin by partially or wholly increasing an inclination angle with respect to a tire rotation axis as compared to an inclined bead seat of a rim. A pneumatic tire forming a tire having a plurality of lids on the surface of the bead base, the lids being axially outside with respect to a normal line to the tire rotation axis. A pneumatic tire, characterized in that it consists collapses inclined Riddji.

[0007]

In the present invention, since the bead base has the inclined ridge which falls outward in the tire axial direction with respect to the normal line to the tire rotation axis, the external force acting on the rim disengages from the outside in the axial direction of the tire. At the same time, the respective inclined ridges resist and the rim detachment resistance is improved. Further, when the rim is assembled, the ridge does not resist because of the inclination direction of the inclined ridge, and there is no difficulty in assembling the rim.

[0008]

EXAMPLE A pneumatic tire 10 of size 155SR13 having the structure shown in FIG. 1 was manufactured as a prototype. This tire has the structure of a normal pneumatic radial tire, ie 1
A pair of bead cores 20, a carcass 30 that is locked by being folded back from the inside of the tire to the outside of the tire, and extends in a toroidal shape, and a carcass 30 has a crown portion 2
The belt 40 has a laminated arrangement of sheets.

FIG. 2 is an enlarged view of the bead portion 50 in FIG. The bead portion 50 is composed of a bead core 20, a carcass 30 that is locked by folding back around the core, and a rubber outer skin 52 that covers these, and the rubber outer skin is a corner that fits into a rounded concave portion of the rim. Round convex bead heel 54,
The rim is formed by intersecting the bead base 56 and the inner wall of the sidewall part with a bead base 56 having a tightening margin by partially or entirely increasing the inclination angle with respect to the tire rotation axis as compared to the inclined bead seat. It forms a bead toe 58.

The bead core 20 used in this prototype tire is a so-called strand bead core formed by winding a rubberized layer of five steel wires in one row four times, but one steel wire is used many times. Other bead cores such as a wound monowire bead core may be used. Further, the bead heel 54 is formed by an arc having a radius of curvature of about 6.5 mm, and this arc extends from the outer end of the bead portion to a position 6.5 mm inward in the tire axial direction. Ridge is arranged.

The ridge includes an inclined ridge 60 which is inclined outward in the tire axial direction with respect to the equatorial plane of the tire. The angle α between the central axis m of the inclined ridge and the normal line n to the tire rotation axis is Although the suitable range differs depending on the angle of inclination of the bead seat that is fitted to the rim to be fitted,
It should be 10 ° to 80 °, and 40 ° for this tire. Also, the distance P between the tips of the inclined lid 60 is 0.05 to 3 mm.
If it is, it is 0.3mm for this tire. Further, the amplitude N of the inclined lid 60 may be 0.01 to 0.5 mm, and is 0.1 mm for this tire.

The line formed by connecting the centers of the amplitudes of the inclined ridges 60 is the same as the line on the bead base surface of a conventional tire, which will be described later, and is approximately 15 ° with respect to the tire rotation axis.
It is a straight line inclined to.

As a comparison, a tire of the same size having the structure of the bead portion 50 shown in FIG. The difference between this conventional tire and the above-mentioned invention tire is the presence or absence of an inclined ridge on the bead base surface.

The test tire thus obtained was rim 13 × 4.
After being assembled to 5J, the following rim detachment resistance test was conducted.

(Rim Release Test 1) This test measures the internal pressure when the rim comes off by lowering the internal pressure with a load of 500 kgf applied to the tire assembly from the side of the tire. is there.

(Rim detachment resistance test 2) This test is conducted when the tire assembly is filled with an internal pressure of 1.8 kgf / cm ² and the load is applied from the side of the tire to cause rim detachment. The load is measured.

In each of the tests, the invention tire 105 was index-evaluated with respect to the conventional tire 100 (the larger the better, the better), and it is clear that the invention tire has excellent rim detachment resistance. became.

[0018] Further, the rim assembly torque when the test tire is assembled by an automatic rim assembly machine, the internal pressure required for the bead portion to be seated on the inclined bead seat of the rim by filling the internal pressure after the rim assembly, and the bead base. When the force generated when the tire was expanded to the diameter was measured, it was found that the conventional tire and the invention tire are almost the same, and it is clear that the invention tire has no difficulty in assembling the rim in comparison with the conventional tire.

[0019]

According to the present invention, it is possible to improve the rim detachment resistance while avoiding the difficulty of assembling the rim.

[Brief description of drawings]

FIG. 1 is a widthwise sectional view of a tire according to the present invention.
Although this cross-sectional view shows only one surface with respect to the equatorial plane of the tire, one surface not shown has a similar structure.

FIG. 2 is an enlarged view of a bead portion 50 in FIG.

FIG. 3 is an enlarged sectional view of a bead portion 50 in a conventional tire.

[Simple explanation of symbols]

 10 Pneumatic tire 20 Bead core 50 Bead section 56 Bead base 60 Inclined ridge

Claims (1)

[Claims] 1. A bead portion for closely fitting to a rim having an inclined bead seat, a rim flange, and a rounded corner recess interposed therebetween, the bead portion including a bead core and a periphery of the core. A carcass that is locked by folding back, and a rubber outer covering that covers them, and the rubber outer covering is different from a bead heel with a rounded corner convex shape that fits into a rounded corner recessed portion of the rim, and an inclined bead seat of the rim. In a pneumatic tire forming a bead base having a tightening margin by partially or wholly increasing the inclination angle with respect to the tire rotation axis, and a bead toe formed by the intersection of the bead base and the inner wall of the sidewall portion. , The bead base has a large number of ridges, and the ridges are inclined ridges that fall outward in the tire axial direction with respect to the normal to the tire rotation axis A pneumatic tire characterized by the following.