JPS61196805A - Pneumatic radial-ply tire - Google Patents

Abstract

PURPOSE:To improve followability with axial compression movements in a shoulder part of a circumferential belt cord ever so high, by setting a modulus of covered rubber in a belt cord ply to being higher at the central part zone but to lower at both side zones, respectively. CONSTITUTION:A tire consists of two carcass plies 11 and 12 set up at angles of 90-75 deg. with the circumferential direction, four circumferential belt plies 21-24 composed of almost parallel cords with the circumferential direction and crossed-belt plies 31 and 32 set up crosswise and symmetrically with each other in the circumferential direction, holding the circumferential belt ply 22 in between. In this case, at two layers off these circumferential belt plies 23 and 24 at the outermost side, there are provided with an outer zone being situated in the axial outside of a tread grounding end P and its width is LW and an inner zone being situated the axial inside of the tread grounding end P and its width is LW', while a central part zone, whose width is CW, is installed in a space between both side zones. And, a modulus of covered rubber at both these zones should be set to being lower than that in the central part zone.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a pneumatic radial tire for high speed/high load use, and particularly to an improvement in the belt structure of a radial tire for aircraft.

(Prior Art) In a pneumatic tire, especially a radial tire for aircraft, a circumferential belt is disposed in the belt layer for the purpose of reducing tread movement and suppressing displacement due to centrifugal force at high speeds, for example. It is disclosed in Japanese Unexamined Patent Publication No. 57-201704 and is well known. In such known technology, the rubber covering the circumferential belt has a relatively high modulus in view of the above-mentioned purpose.

(Problems to be Solved by the Invention) However, in conventional radial aircraft tires having a circumferential belt layer, another problem arising from coating the belt layer with high modulus rubber has been effectively solved. cannot be resolved.

In other words, in such a radial tie, when the load is high, a part of the shoulder of the two-belt layer is compressed inward in the axial direction of the tire, and the cord spacing becomes narrower, but because the coating rubber has a high modulus, the belt The compressive behavior of the cord cannot be followed, and as a result, separation occurs at the interface between the cord and the rubber or between the shoulder belt layer and the tread layer.

(Necessary Means for Solving Problems) The present invention provides a tire that can easily make the rubber covering of the belt cord follow the axial compression behavior of the shoulder part of the circumferential belt cord under high load. The present invention seeks to solve the aforementioned problems while maintaining the advantages of the prior art.

That is, the present invention provides at least one circumferential belt layer located at the outermost radial direction, and a region on both sides including the axially outer region of the tire crown contacting end, and a central region located between these both regions. It is characterized in that the modulus of the covering rubber in both side regions is set lower than the modulus of the covering rubber in the central region.

(Operations and Preferred Embodiments) According to the present invention, when the shoulder part of the belt layer is compressed axially inward during high load, the coating rubber has a low modulus in the region on both sides corresponding to the shoulder part. can effectively follow the behavior of the shoulder part of the belt layer, making it possible to accurately prevent undesired separation at the interface between the cord and the rubber, as well as between the belt layer of the shoulder part and the tread layer. Moreover, since high modulus rubber coating is placed in the center of the tread,
Both tread movement and displacement caused by centrifugal force can be effectively suppressed, and the low modulus coating rubber in both side regions has almost no adverse effect on these.

In the above-described structure of the present invention, the ratio of the modulus of the coating rubber in both side regions of the at least one belt layer and the modulus of the coating rubber in the central region at 100% elongation is less than 0.33. If it is, then part of the shoulder belt layer becomes too soft over a wide range, resulting in uneven wear.If it exceeds 0.9, it is because the modulus of the covering rubber is locally varied. It was found that the original separation prevention effect could not be sufficiently exhibited. Therefore, in a preferred embodiment of the present invention, the ratio of the modulus of the coating rubber is 0.33 to 0.9;
It is desirable to set it within the range of 0.4 to 0.83.

Furthermore, since the modulus of the coating rubber is relatively low in both side regions of the belt layer including the axially outer region of the tire crown contact end, it is necessary to It was also found that part of the shoulder became too soft over a wide area, making uneven wear more likely.

Therefore, in a preferred embodiment of the present invention, when both sides of the belt layer include a region located inward in the axial direction of the tire crown, the width of the inner region is set within about 30% of the ground contact width to prevent occurrence of uneven wear. It is desirable to be able to effectively prevent this.

(Example) Hereinafter, the present invention will be described with reference to illustrated embodiments.

The drawing shows the present invention in tire size H46X18. This shows an example of application to an OR20 aircraft radial tire, and represents the belt structure of the same tire.

The tire of this example has two carcass layers 11 and 12 arranged at an angle of 90 to 75 degrees with respect to the circumferential direction, and a four-blade circumferential belt made of cords substantially parallel to the circumferential direction. layers 21, 22, 23, 24, and cords forming an angle of 67° with respect to the circumferential direction, intersecting belt layers 31. It has a belt structure composed of 32. The circumferential belt layers 21, 22, 23, 24 and the intersecting belt layers 31, 32 are all made of aromatic polyamide fibers (3000 d/3).

The two outermost circumferential belt layers 23 and 24 are located outside the tread contact edge P in the axial direction and have a width Lw, and are located inside the tread contact end P in the axial direction and have a width Lw.
11i', and the area between these side areas 41 and 42 having a width Cw is set as a central area. Width L of the inner area in both side areas
w/ is the distance between the tread contact edges P, that is, approximately 10% of the contact width Tw. These circumferential belt layers 23.2
The covering rubber of No. 4 is 60 kg 70 m2 in the central area.
, it has a modulus at 100% elongation of 37 kg/cm2 on both sides.

(Effects) In order to confirm the effects of the present invention, the modulus of the coated rubber at 100% elongation was 60 kg / 60 kg /
Comparative tires with a diameter of 0 m2 and tires A, B of the present invention,
A comparative test was conducted on both C and C. That is, after running each test tire on a drum for 5,000 km under a normal load, the length of the crack at the interface between the circumferential belt cord of the outermost layer and the covering rubber was measured. The measurement results are shown in the table below.

As is clear from these measurement results, according to the present invention, by setting the modulus of the coating rubber of the belt cord layer to be relatively high in the central region and relatively low in both side regions, the shoulder part of the circumferential belt cord is As a result of the increased ability to follow the axial compression behavior under high loads, it is possible to effectively suppress the occurrence of separation at the interface between the cord and the rubber, and also to prevent separation between the belt layer and the tread layer in some shoulder areas. It also prevents separation.

That is, the present invention can fully achieve its intended purpose.

BRIEF DESCRIPTION OF THE DRAWINGS The drawing is a diagrammatic sectional view showing a belt structure in a radial tire for aircraft according to an embodiment of the present invention. 11.12...Carcass layer

Claims (1)

[Claims] 1. A belt comprising at least one carcass layer arranged at an angle of 90 to 75° to the circumferential direction and at least two layers consisting of cords arranged substantially parallel to the circumferential direction. In a pneumatic radial tire having a pneumatic radial tire, at least one belt layer located at the radially outermost layer has both side regions including the axially outer region of the tire crown ground contact end;
A pneumatic radial tire comprising a central region located between these both side regions, wherein the modulus of the covering rubber in the both side regions is set lower than the modulus of the covering rubber in the central region. 2. In the pneumatic radial tire according to claim 1, the ratio of the modulus of the coating rubber in both side regions of the at least one belt layer to the modulus of the coating rubber in the central region is 100% elongated. The value of 0.33 to 0.9
A pneumatic radial tire characterized by being within the range of. 3. In the pneumatic radial tire according to claim 2, the ratio of the modulus of the coating rubber in both side regions of the at least one belt layer to the modulus of the coating rubber in the central region is 100% elongated. 0.4 to 0.83 with the value of
A pneumatic radial tire characterized by being within the range of. 4. In the pneumatic radial tire according to claim 1, both side regions of the at least one belt layer are located inside the tire crown ground contact end in the axial direction, and have a width of about 30 mm of the ground contact width. A pneumatic radial tire characterized in that it includes an inner area within %.