JPS59124415A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To improve the rim slip-off preventing performance by specifying the relation between the diameter and inclination angle of a bead base and a rim sheet, and the ratio between each height of bead bundle, bead base center part, and bead toe, and the tightening length of each part. CONSTITUTION:The inclination angle beta of a bead base part 22 with respect to the revolution shaft of a tire is made larger than the inclination angle alpha of a rim seat part 82, and the diameter Dt of the bead base part 22 is set to the value Dr of a rim diameter or less, and the ratio epsilon1 of the tightening length l1 between the bead base part 22 and the rim seat part 82 at the position of a bead center O with respect to the height L1 ranging from a bead bundle 21 to the bead base part 22 in the direction of an equator plane is set to 0.4-0.6, and the ratio epsilon2 of the tightening length l2 at this position with respect to the height L2 ranging from the bead bundle 21 to a bead toe 24 is specified to epsilon1 or less. With such constitution, the rim slip-off preventing performance can be improved without damaging the fiting performance onto the rim.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire that has improved rim removal performance without impeding fitability to a rim.

In the first place, the meridional cross-sectional shape of the bead portion of the tire is designed based on the shape of the rim to which the tire is assembled, so as to achieve both fitability between the tire and the rim and performance to remove the rim.

Generally, the meridional cross-sectional shape of the rim used for passenger cars is
As shown in Figure (al), the inclination angle α of the rim seat portion 1 of the rim 8 is between 0° and 6° with respect to the axis parallel to the rotational axis of the tire.
The tire is inclined radially inward within a range of °.

Therefore, conventional tires mounted on such rims 8 are
As shown in FIG. 1 (bl), in order to improve fitting performance, the diameter Dt at the bead heel portion 2 of the tire is set to be the same as or slightly smaller than the rim diameter Dr of the rim 8, and the bead portion 5 of the tire When the bead heel portion 2 of the tire is inserted into the rim flange 3 due to internal pressure, the fitting pressure when the bead heel portion 2 of the tire is inserted into the rim flange 3 is reduced.

However, with such a relationship between the diameter Dt of the bead heel portion 2 of the tire and the rim diameter Dr of the rim 8, when the bead portion 5 of the tire is fitted to the rim 8, the bead base portion 4 of the tire and the rim seat portion of the rim 8 are Since the interference l between the bead portion 5 and the rim seat portion 1 is small, the fitting force of the bead portion 5 to the rim seat portion 1 is not sufficient. Therefore, the bead portion 5 tends to move inside the rim 8 due to the lateral force acting on the tire when cornering or the like with low air pressure, often causing the problem of the rim coming off.

In order to prevent this problem, in conventional tires, the inclination angle β of the bead base portion 4 of the tire is adjusted as shown in Figure 2 (al).
8 degrees inward in the radial direction with respect to the axis parallel to the tire rotation axis
30'' and larger than the inclination angle α of the rim seat portion 1 of the rim 8, and furthermore, this inclination angle is set to 2 steps “β′” in the area of the bead toe portion 6 of the tire as shown in FIG.
As shown in bl, the tightening margin l' between the bead base part 4' and the rim seat part 1 of the rim is increased, and at the bead toe part 6,
'We are trying to obtain mating force.

However, as mentioned above, in the shape of the bead base part having two steps of inclination, as the bead heel part 2 of the tire is inserted into the rim flange 3 side due to the increase in internal pressure,
As shown in Fig. 3, the second stage inclined bead base part 4'
9 gets stuck in the rim hump part 7, and a higher internal pressure is required to completely fit the bead base part 4 of the tire into the rim rim seat part 1, resulting in an increase in the fitting pressure. That is, a problem arises in that the fitability deteriorates.

Furthermore, with such a bead thrust part shape, the bead toe part 6 rests on the rim seat part 1 due to high internal pressure.
When the internal pressure decreases, the bead portion 5 tends to move toward the inside of the rim, so there may be cases where no improvement in rim detachment performance is observed.

In addition, in conventional tires, the inner diameter Db of the bead bundle has been reduced in order to increase the fitting force.
In this case, the compression ratio of the bead bundle increases and the fitting pressure increases. In other words, the fitability will be poor.

As mentioned above, in conventional tires, the ability to come off the rim and the ability to fit onto the rim have been in a contradictory relationship.

Accordingly, an object of the present invention is to include a pair of air-filled sidewall portions that improve the ability to come off the rim without impeding fitability to the rim, and a tread portion located between the sidewall portions, and a tread portion having at least one layer. In a pneumatic tire in which the carcass layer is formed by rolling up a pair of left and right bead bundles located at the bead portion, the inclination angle β of the bead base portion with respect to the tire rotation axis is greater than the inclination angle α of the rim seat portion of the rim, and the bead heel portion The diameter Dt is less than or equal to the rim diameter 1)r, and the total axial width W and the total equatorial height H of the bead bundle
The ratio ε1 of the interference l between the bead base and the rim seat at that position to the height in the equatorial plane from the bead bundle to the bead base at the point of intersection 0 (hereinafter referred to as bead center) of each center line of is 0.4 to 0.6, and the ratio ε2 of the interference 12 between the bead toe and the rim seat at the bead toe position to the equatorial height L2 from the bead bundle to the bead toe is equal to The gist of the present invention is a pneumatic tire characterized by a ratio ε1 that is smaller than ε1.

Hereinafter, the present invention will be explained in detail by way of examples with reference to the drawings.

4 to 6 show a pneumatic tire according to an embodiment of the present invention, in which FIG. 4 is an explanatory diagram of a meridian half cross section, FIG. The figure is an enlarged sectional view of a main part, that is, a bead part, of another embodiment.

In the figure, reference numeral 10 denotes a radial tire according to an embodiment of the present invention, which includes a pair of left and right bead portions 20, a pair of left and right sidewall portions 60 connected to the bead portions 20, and a radial tire located between the respective sidewall portions 60. A single carcass layer 50 consisting of a tread portion 40 and having a cord angle of substantially 9σ with respect to the tire circumferential direction is attached to the pair of left and right bead portions 2.
0, and both end portions thereof are folded back from the inside to the outside by a pair of left and right bead bundles 21 located in the bead portions 20 to form a pair of left and right folded portions 50a. Each folded part 50a wraps around the pair of left and right bead fillers 60 located on this bead bundle 21 and comes into close contact with the carcass layer 50 before folding, and furthermore, a cord in the tire circumferential direction is placed on the carcass layer 50 at the tread part 40°. Belt layers 70 are arranged which intersect with each other at an angle of 15° to 30°.

In the present invention, the inclination angle of the bead base portion 22 of the bead portion 20 with respect to the tire rotation axis is β,
If the inclination angle of the rim seat part 82 of the rim 80 with respect to the tire rotation axis is α, then β>α, that is, the inclination angle β of the bead base part 22 with respect to the tire rotation axis should be made larger than the inclination angle α of the rim seat part 82. On the other hand, the diameter pt of the build heel portion 23 is equal to or smaller than the rim diameter Dr, that is, Dt≧l)r.

Further, in the present invention, the respective center lines BB and A of the total axial width W and the total height H in the equatorial direction of the bead bundle 21 are
- Bead bundle 2 at intersection O (hereinafter referred to as bead center O) of A
The height in the equatorial plane direction from the lower surface 21a of 1 to the bead base portion 22a, and the bead base portion 22 at this position relative to
The ratio ε1 of the tightening allowance/, between a and the rim seat portion 82a is 0.
Range from 4 to 0.6, i.e. '+ = ''/L, =
0.4~'0.6 tL tel.

Note that this 61 is also approximately equivalent to the compressive strain at the center position of the bead bundle.

Furthermore, in the present invention, the lower surface 21 of the bead bundle 21
ad; The interference I between the bead toe portion 24 and the rim seat portion 82b at the position of the bead toe portion 24 with respect to the height L2 in the equatorial plane direction from the bead toe portion 24 to the bead toe portion 24! The ratio ε2 of 2 is smaller than the ratio ε1 at the center position of the bead bundle 21 described above,
That is, ε2='/L2<ε.

It's Toshide.

Note that the tightening margin l at the center position of the bead bundle 21 described above is defined as the inner diameter of the rim seat portion 82a at the center position of the bead bundle 21, where l)n is the inner diameter of the rim seat portion 82a at the center position of the bead bundle 21, and the bead base portion 2 at the center position of the bead bundle 21.
If the inner diameter of 2a is [)m, it can be expressed as follows. Therefore, the ratio ε at the center position of the bead bundle can be expressed as follows.

Similarly, the tightening allowance I at the bead toe portion 26 position! 2 is
If the inner diameter of the rim seat portion 82b at the position of the bead toe portion 24 is DJ, and the inner diameter of the bead toe portion 24 is l)k, it can be expressed as follows. Therefore, the ratio ε at the bead toe part
2 can be shown as. Note that this 62 is approximately equivalent to the compressive strain at the bead toe position.

Note that the above-described total axial width W and total equatorial height H of the bead bundle 21 do not include the thickness of the insulating rubber 21b present on the outer surface of the bead bundle 21.

As described above, in the present invention, the inclination angle β of the bead base portion 22 with respect to the tire rotation axis is changed to the inclination angle α of the rim seat portion 82.
The diameter Dt of the bead heel portion 26 is made smaller than the rim diameter Dr, so that when the tire 10 is fitted to the rim 80, a fitting force with the rim 80 is generated over the entire bead space portion 22. be able to.

In addition, the value of ε1 is set within the range of 0.4 to 0.6, and ε
Since 1>ε2, it is possible to improve the rim removal performance without impairing the fitability to the rim, as shown in the results of experiments described later.

Furthermore, the reason for setting the value of ε1 within the range of 0.4 to 0.6 is that, as shown in the experimental results described later, when the value of ε1 is less than 0.4, the fitting force with the rim 80 decreases. This is because the rim removal performance deteriorates, and if it still exceeds 0.6, fitting to the rim 80 becomes impossible.

The reason why ε1>ε2 is still set is the bead part 20 of the tire 10.
When fitting to the rim 80, if only the bead base portion 22a at the center of the bead bundle 21 lifts up the hang portion 7 of the rim 80, other parts of the bead base portion 22 will ride up the hang portion 7. This is because it is easy to do so, and therefore the increase in fitting pressure is suppressed to a slight increase, and the fitability to the tab rim is not inhibited.

In the second embodiment of the present invention shown in FIG. 6, the inclination angle β of the bead base portion 22 with respect to the tire rotation axis is increased toward the bead toe portion 24 at the intermediate portion of the bead base portion 22 as shown in the figure. This is an example of β'.

Note that the inclination angle β of the bead base portion 22 is 2° to γ larger than the inclination angle α of the rim seat portion, and the bead heel portion 22
It is preferable that the diameter pt is equal to or smaller than the rim diameter [r] in the range of 0 to 2.0 mm from the viewpoint of achieving both fitability to the rim and performance for coming off the rim.

The results of the experiment will be explained below.

Example The specifications of the tires used in this experiment were as shown in Table 1.

Table 1 Note that for each tire, the inclination angle β of the bead base with respect to the tire rotation axis is also 4° larger than the inclination angle α of the rim seat part of the rim, and the diameter Dt at the bead heel is the rim diameter. It is formed smaller than Dr in the range of 0.8 to 1.6 mm.

Furthermore, each tire has a single carcass layer and a polyester reinforcing cord, the angle of the cord to the circumferential direction of the tire is 90°, and two bell and toe layers are arranged, and the reinforcing cord is a steel cord. The cord angle with respect to the tire circumferential direction is 17 degrees, and the cords intersect with each other.

The tire size is 1658R13, and the rim width is 4-layer inches. ,' Using the tire described above, the fitting force, rim removal air pressure, and fitting pressure were measured as follows.

(al Fitting force...The rim diameter of the 8-divided rim was increased and the total tightening force when the diameter was the median value specified in JIS D 4218 was measured as the fitting force.

(b) Air pressure when the tire falls off the rim: Apply a lateral force of 9 to the 635 in a static state and measure the air pressure when the tire falls off the rim.

(C) Fitting pressure: Measure the fitting pressure when assembling the rim.

The results of the above measurements are shown in Table 2.

Table 2 Examples Tires and ε1. used in Experimental Example 1 described above. Using another tire of the present invention in which only ε2 was different from Experimental Example 1, the relationship between ε1 and fitting force was measured, and the results are shown in FIG.

As is clear from Table 2 and FIG. 7, the pneumatic tire of the present invention has an increased fitting force and greatly improved rim removal performance, while at the same time slightly reducing the increase in fitting pressure to the rim. It can be seen that the fit to the rim is not hindered by the pressure.

Since the present invention is configured as described above, it is possible to improve the performance of removing the rim without impairing the fitability to the rim.

[Brief explanation of the drawing]

Figures 1 to 3 are explanatory diagrams for explaining the rim detachment phenomenon, Figures 4 to 6 show pneumatic tires according to embodiments of the present invention, and Figure 4 is an explanatory diagram of a meridional half cross section. , 5th
The figure is an enlarged explanatory view of the main part of the above, that is, the bead part, and FIG. 6 is an enlarged cross-sectional explanatory view of the main part of another embodiment, that is, the bead part,
FIG. 7 is a diagram showing the results of the experiment. 20... Bead portion, 21... Bead bundle, 22-...
Bead base part, 23... Bead heel part, 24...
・Bead toe part, 60...Side wall part, 40-
...Tread portion, 50...Carcass layer, 70...
Belt layer, 80... Rim, 82... Rim seat portion. Figure 1 (a) (b) Figure 3 Figure 4 Figure 5 Wharf Figure 6 0 Figure 7 Figure 1 ε1(τ)

Claims (1)

[Claims] A pair of left and right bead bundles consisting of a pair of left and right bead parts, a pair of left and right sidewall parts connected to the bead parts, and a tread part located between the sidewall parts, and at least one carcass layer is located in the bead part. In a pneumatic tire made by rolling up
) is less than or equal to the rim diameter (Dr), and the bead bundle at the intersection point (0) (hereinafter referred to as bead center) of the respective center lines of the total axial width (W) and the total equatorial height H) of the bead bundle The interference between the bead base part and the rim seat part at this position (I
! , ) is 0.4 to 0.6, and the interference (j A pneumatic tire characterized in that the ratio (ε2) of '2) is smaller than the ratio (ε1) at the center position of the bead bundle.