JPS595601Y2 - radial tire wheels - Google Patents

Description

[Detailed explanation of the idea] This invention relates to a radial tire wheel.

This invention relates to an improvement in the incorporation of a flap that protects the tube of a pneumatic tire whose carcass has a radial structure, particularly a radial tire used for trucks, buses, or larger vehicles.

In general, tire flaps are installed between the wheel rim and tube inside the left and right bead portions of the tire, and include a cylindrical base part that runs along the circumference of the wheel rim, and a cylindrical base part on both sides of this cylindrical base part. It has a pair of annular wing parts that are in contact with the inner surface of the bead part of the tire, and is extruded or shaped into an endless shape using rubber or an elastic material similar to rubber so that the cylindrical base part and the annular wing part form a gutter-shaped cross section. Made by joining or molding.

Conventionally, when a tire flap is assembled with a tire rim and filled with the proper internal pressure, the height of the wing part on the outer circumference of the wheel rim exceeds the flange height of the standard wheel rim, and the bead part of the tire It is customary to be dimensioned to protrude between the tube and the tube.

Such a tire flap is suitable for use in bias tires, especially tires for which a large number of car force splies are wound around multiple bead cores to firmly compact the bead area, such as tires for large vehicles such as those mentioned above. We have achieved excellent tube protection.

However, in recent years, there has been remarkable progress in the radial radial engine, which has been actively developed for use in large vehicles such as the one mentioned above.
Due to the peculiarity of carcass reinforcement, the tire's side portion deflects particularly greatly within the cross section that includes the rotational axis of the tire due to the wheel load. At the periphery of the wing portion of the tire flap f located in this way, a part of the tube t that faces and contacts the step between this flap and the inner surface of the tire becomes locally and severely rubbed due to the transfer accompanied by the tire load. ,
The tube t is prone to local fatigue in the circumferential direction along the periphery of the wing portion, which causes cracks that can lead to punctures, and a problem that is contrary to the purpose of protecting the tube is frequently experienced.

In FIG. 1, C is the crown portion of the tire, b is the bead portion, bt is the bead toe portion, S is the side portion, and r is the wheel rim.

It has been clarified that such fatigue fracture of the tube t occurs in the following manner.

As shown in Figure 2 a and b for a radial tire with belt reinforcement on the radial carcass, comparing the cross-sectional shape with that of a conventional bias tire, the bead spacing Wr of the bias tire before filling with internal pressure is Generally, the bead spacing is much narrower than the bead spacing wb, and while the sidewall thickness of radial tires is relatively thin, chafer reinforcement (not shown) is incorporated in the bead. The inner surface of the bead part is not smooth and monotonous like a bias tire, but protrudes inward with a considerably large curvature.
, c shows the process before and after assembling the rim and filling the internal pressure. As shown in the diagram, the periphery of the wing part of the flap f is first captured between the bead of the tire and the tube at the height of the tube T attached to the tire. During this period, the cylindrical base portion of the flap f is moved toward the center of the axis. However, since the inner surface of the bead of the radial tire has a shape that protrudes inward, the wing section is fixed under clamping pressure between the inner surface of the bead and the outer surface of the tube at the initial circumferential height hw. be done.

On the other hand, with bias tires, Figure 4 a, l
), as shown in c ('This is a smooth inner surface of the bead part, and the bead part distance is quite wide from the beginning■), and there is a flap f.
The cylindrical base part is first pressed against the circumferential surface of the wheel rim r, and then the annular wing part easily slides along the bead part and is pressed against the bead part while fitting therein.

In this way, the height of the peripheral edge of the wing portion of the flap f, which is fixed by filling the tube with internal pressure, hw in a radial tire is much higher than hb in a bias tire.

However, during the load transfer of the tire, as mentioned above, the side part of the tire from the rim flange to the tread shoulder is largely deflected, and the maximum tensile strain occurs on the inner surface of the tire near the rim flange height, causing the tire and tube to come into close contact. Because it is in the state
When a tire becomes distorted, a similar distortion occurs in the tube as well.

However, by inserting a highly rigid flap between the tire and the tube in the height area near the rim flange, the strain on the tire is alleviated by the flap, and the strain on the tube in the area where the tube and flap overlap. However, in the area where the tire and tube are in direct contact, the tube will receive the strain of the tire.

That is, the tube is subjected to concentrated strain at the periphery of the wing portion of the flap f.

In this way, the repeated action of concentrated strain caused by the radial tire rolling under load causes fatigue fracture of the tube at the boundary of the strain distribution.

Here, the internal strain near the tire bead was measured using a 10.0O R 20 radial tire for trucks and buses.
As shown in Fig. 5, the strain has a peak value near the 110% position relative to the rim flange height hf, and although the strain decreases in the area U closer to the tread than the peak position, its absolute value is large under load. While the strain amplitude due to the load is also large, the absolute value of strain decreases drastically in the region d lower than the flange height, and therefore the strain amplitude due to the applied load is also small.

Here, strain amplitude = strain in the area directly under the load (with maximum value)
Since this is the strain at the top of the tire opposite to the contact area (strain=O), it goes without saying that the larger the strain amplitude, the greater the amount of strain in one rotation of the tire.

As shown in Fig. 5, the same strain distribution was observed even in tires in which the terminal end e of the wire chafer W was stopped at e' directly below the bead part b. .

Based on the analysis results of the mechanism that leads to the occurrence of tube cracks, the risk of tube crack failure can be summarized as follows.

(Large less than 40%) The wing height of the flap is 1 of the standard rim flange height.
When the height exceeds 0.5%, stress concentration occurs in the tube, causing tube crack failure.

2 Caution area (over 140%) Stress concentration is reduced at positions where the flap wing height is higher, but the strain amplitude during load transfer is large and the possibility of tube cracking remains.

3 Safety range (l05% or less) When the wing height of the flap reaches a position below 105% of the flange height, the absolute value of strain decreases drastically at this position, and the strain amplitude during load transfer is also small, so the tube Good resistance to cracking.

As mentioned above, in conventional flaps, the entire periphery of the wing part is located in the dangerous or caution area, and the above tendency is even more pronounced in cases where the flap has a single-chafer winding structure and its inner edge is at the same height as the flange. It appeared.

In order to understand the relationship between the height of the wing part of flap f and tube failure, radial tires for trucks and buses of 10.0O were used.
According to the results of numerous actual vehicle running tests carried out under 200% load by incorporating various flaps with different flap end heights into the R20, there were no tube cracks in the above safe range, and there were no tube cracks in the dangerous or critical range. Cracks occurred quite frequently in those in the caution range.

It has been found that if the height of the peripheral edge of the annular wing portion 3 of the flap f is lowered in this way, no failure will occur, but on the other hand, there is a problem that the flap may be placed one-sidedly when assembling the rim.

In other words, when hw/hf becomes less than 0.85, the annular wing part of the flap does not fit into the bead part b of the tire, so the tube protrudes, and the tube t gets caught between the tire and the rim or between the flap and the tire, causing a tube puncture. .

Experiments have shown that the optimal base width is 45% to 50% of the standard rim width; however, if it is less than 45%, there is a risk of one-sided insertion as described above, and the annular wing part of the flap will be damaged. There is a concern that the tube may not fit well with the bead part b of the tire, resulting in a tube puncture, and if it exceeds 50%, there is a risk that workability when attaching the flap to the tire may become difficult.

Furthermore, increasing the outward opening angle α of the flap wing portion to about 65° to narrow the total width of the flap had an effect on the rim assembly workability.

The height of the wing portion of the flap f must be at least 20 mm higher than the bead toe portion when it is installed.

An example of the flap used in this invention is shown in Fig. 6, in which 1 is a cylindrical base part, 2 is a bent part, and 3 is an annular wing part. Results of an actual vehicle running test in which this flap was incorporated into a radial tire. An example of this was as follows.

Test conditions Test Vehicle: Flat body E2-D4 Load: Transporting steel materials (200% load) Tires used: 10,00 R 2014 PR:
(Steel radial tires for racks and buses) Note 1 Tube cracking occurred after running for 42,000 hours Note 2 7.
Tube cracking occurs after running for 50,000 hours Note 3 5,000km
The tube protruded when measuring the rim after running it in.

Note 4: After running 50001an, there were signs of tube protrusion when the rim was removed and measured.

The height hw of the periphery of the wing part 3 of the flap is set to a safety range of 10.
5%hf or less and no tube protrusion 8
It has been confirmed that it is better to arrange it at 5% hf or more.

Thus, this invention advantageously solves the problem that radial tires, due to their unique carcass reinforcement, get caught in the periphery of the wing part of the flap, causing fatigue rupture of the tube, and protects the tube with the flap. This purpose can be fulfilled especially for radial tires.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing how a radial tire wheel deforms before and after loading, Figure 2 a, l) is a comparison diagram showing the difference in cross-sectional shape between a radial tire and a bias tire. Figure 4 is a comparison diagram showing the process of rim assembly and internal pressure filling for radial tires and bias tires.
The figure is a cross-sectional strain diagram of a radial tire, and FIG. 6 is a cross-sectional view of a flap used in this invention. r...wheel rim, b...bead part, bt...bead toe part, 1...cylindrical base part, 2...bending Part, 3... Annular wing part.

Claims (1)

[Scope of utility model registration request] A cylindrical base part that runs along the circumference of the wheel rim on which the tire is assembled, and a pair of annular wings that extend along the inner surface of the tire bead from the bent part that contacts the bead toe part of the tire on both sides of this cylindrical base part. In wheels where a radial tire incorporates a flap that separates the tube that controls tire inflation from the circumference of the wheel rim and the bead of the tire, the width of the cylindrical base of the flap is the standard rim width. 45 to 50% compared to the standard wheel rim, and the height hw of the periphery of the wing part of the flap when filled with the normal internal pressure after assembling the tire rim is 85% or more and 105% of the flange height hf of the standard wheel rim. A radial tire wheel characterized by a range that cannot be exceeded.