JPS63103706A - Pneumatic radial tire for high speed heavy load - Google Patents

Abstract

PURPOSE:To promote lightening the weight of a tire without spoiling durability by providing a belt consisting of a carcass of trochoid state radial structure and a belt consisting of multiple wrapping layers wrapping its crown part and by arranging a rubber squeeze between specific layers of the belt. CONSTITUTION:A carcass 1 is formed in trochoid state radial structure consisting of plies of organic fiber cords arranged in parallel with each other. And the circumference of the crown area of the carcass 1 is wrapped with a belt 2 consisting of multiple wrapping layers of the concentric organic fiber cords in the close spiral coil state. At this time, the outermost layers isolated from the carcass 1 are called as the nth layer, the (n-1) layer and the (n-2) layer in order, and a rubber squeeze 4 is arranged in the neighborhood of both the width end rims of the belt 2 between the nth layer and the (n-1) layer. By this, lightening of the weight of a pneumatic radial tire used for airplane rubber wheels and so forth can be achieved without spoiling durability.

Description

[Detailed Description of the Invention] (Industrial Application Field) In general, aircraft radial tires are a typical example.
The following describes the results of development research related to improving the durability of pneumatic radial tires, which are used under similar operating conditions at high speeds and under heavy loads.

Aircraft tires are becoming increasingly faster and faster due to demands for mass transportation.
The conditions for heavy loads are becoming stiffer, and at the same time there is a strong demand for weight reduction, and further improvements in durability are desired from a safety standpoint.

Radialization of the carcass reinforcement structure is useful from the perspective of reducing the weight of the tire, but the results of prototype experiments have shown that the tread layer near the ground contact point is affected by high loads (during aircraft taxiing). Internal shear strain concentrates,
It has become clear that separation often occurs at the belt and tread interface, which tends to impair the durability of the belt.

In order to reduce the in-plane shear strain at the belt and Toledo interface, increasing the cord insulation diameter of the belt is effective. This results in an undesirable increase, and thus improving belt durability and reducing the weight of the diamond become mutually exclusive conditions.

(Prior art) Regarding the durability of pneumatic radial tires for aircraft,
At present, there are no reports in known literature regarding attempts to achieve both weight reduction.

(Problem to be solved by the invention) When a pneumatic radial tire for high-speed, heavy-duty use runs under high loads such as during a taxi, it is possible to reduce the chance of separation occurring due to the difference in in-plane shear strain at the interface between the belt and the tread. An object of the present invention is to advantageously achieve both durability and light weight of a tire by sealing the belt without increasing its weight.

(Means for Solving the Problems) This invention provides a carcass with a toroidal radial structure consisting of plies of organic fiber cords arranged in parallel to each other, and a tightly wound helical coil concentrically around the crown region of the carcass. and a belt consisting of multiple winding layers of organic fiber cord surrounding the belt, and the multiple winding layers of this belt are
The outermost layer separated from the carcass is the n-th layer.
1) It is characterized by having a thin rubber squeegee sandwiched between the N and/or further between this and the n-2th layer in a region near both width ends of the belt.
This is a pneumatic radial tire for high speed and heavy loads.

Now, FIG. 1 shows the main parts of a pneumatic radial tire for aircraft according to the present invention in a cross section including the tire rotation axis, and in the figure, 1 is a carcass, 2 is a belt, and 3 is a tread layer.

The carcass 1 has a toroidal radial structure consisting of two plies of organic fibers, e.g. aramid fiber cords, arranged parallel to each other, in the illustrated example, and a closely wound helical coil concentrically around the crown region of the carcass 1. Sturdy hoop-like reinforcement is provided by the belt 2 consisting of multiple layers of organic fibers, for example aramid fiber cords, which are wrapped in a coil, six layers in the illustrated example. The belt 2 may sometimes include a narrow additional winding layer 2' having a width of 0.6 to 0.7 times the half-width W of the belt 2 in the widthwise central region of the belt 2, as shown.

The winding layer of the belt 2 is an additional winding [this is also the same when using 2', but one cord or at most 2.3 cords is coated with rubber, and the carcass is wrapped tightly in the form of a spiral coil. By concentrically wrapping around the crown region of the tire, the cord direction is at a very shallow angle to the tire circumference, often referred to as circumferential alignment.

Now, the multiple winding layers of the belt 2 are generally excluded from additional winding layers, with the outermost layer separated from the carcass 1 being the n-th layer, the (n-1)th layer, the (n-2)th layer, and so on. In FIG. 1, the layer is referred to as a layer, and in FIG. Particularly preferably, a rubber squeegee 4 is disposed between the width ends and extends within 0.3 times the half width W of the belt 2.

This rubber squeegee 4 preferably has a width approximately 0.04 times or more the above-mentioned half width W.

Here, the half width W of the belt 2 is generally 0.4 to 0.6 times the ground contact width of the tread layer 3 (for the width 2W of the belt 2, it is 0.8
It has already been found that a range of 1.2 to 1.2 times is necessary in order to adapt to high-speed usage conditions such as aircraft tires.

The rubber squeegee 4 has an outer diameter d of 0.00 mm, with the outer diameter d excluding the rubber coating of the organic fiber cord used for the winding layer of the belt 2ψ, as a reference.
It is desirable that the thickness be in the range of 25 to 1.0 times.

(Function) Now, the test tire of size H46-18R20 shown in FIG. Regarding the distribution of principal shear strain, which is a factor in the occurrence of separation 5, Figure 3 shows the calculation results using the finite element method in comparison with a comparison tire.

In this test, the rubber squeegee 4 had a thickness of 0.5 tm (0,
426) Width 55mm (0,31w) size JIS
Hardness JIS 6361 JIS hardness type A) 43-4
8. Modulus at 100% elongation 25. Okgf/aa
As shown in the solid line in Fig. 3, the results when the belt 2 is sandwiched only between the n1 (n-1) layer as the physical properties of z are shown in the solid line in Fig. 3. The difference in principal shear strain at the boundary between the outermost layer and the tread layer 3 is significantly reduced.

In addition, in the reference example in which a rubber squeegee is applied between all the winding layers of belt 2, the distribution of principal shear strain is desirable as shown by the chain line in the same figure, but on the other hand, the increase in the total gauge of belt 2 , there is a disadvantage of temperature rise,
Therefore, it has been found that the rubber squeegee can only be placed between the nth and (n-1) layers, or at most between the (n-1) and (n-2) layers.

Furthermore, the heat generation that causes this temperature rise is related to the thickness t of the rubber squeegee 4, as well as the reduction in the step of the principal shear strain. As shown on the horizontal axis, the magnification of the thickness t with respect to the cord diameter d is 0.25d to 1. In the thickness range of Od, the difference in principal shear strain can be reduced while effectively suppressing heat generation.

(Example) A test comparing the durability enhancement effect of rubber squeegees with widths of 6011 and various thicknesses using a six-wound layer of Kevlar cord with cord diameters of 1.2 and 1.51 φ for the belt 2. The results are shown in Table 1.

This test is 120% TAXI specified in TSO-C62.
In a drum durability test according to the conditions, the drum rotation speed at which separation occurred in the trend layer near the ground contact ring,
Immediately after completing this test, a sensor was inserted into a measurement hole that had been previously drilled in the tread layer 3 to a depth of 0.5 th directly above the belt 2 with an extremely small diameter that did not affect durability at all, and the highest temperature was measured. evaluated.

(Effects of the Invention) According to the present invention, it is possible to reduce the weight of pneumatic tires, such as rubber wheels for aircraft, which are used under harsh running conditions under high speed and heavy loads, without deteriorating their durability.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a pneumatic radial tire according to the present invention, Fig. 2 is a cross-sectional view of a comparative example, Fig. 3 is a principal shear strain distribution diagram, and Fig. 4 shows that the thickness of the rubber squeegee affects the principal shear strain. It is a graph showing the effect of height difference and heat generation. 1...Carcass 2...Belt 3...Tread layer 4...Rubber squeegee Figure 3 Figure 4 (%) (kfF/mrn) Mus A-g thickness

Claims (1)

[Claims] 1. A carcass with a toroidal radial structure consisting of plies of organic fiber cords arranged parallel to each other, and multiple wound layers of organic fiber cords wrapped around the crown region of the carcass in a tightly wound spiral coil concentrically with the crown region of the carcass. The belt has multiple winding layers, the outermost layer separated from the carcass is the nth layer, and/or the (n-1)th layer and/or the interlayer between this and the n-2nd layer. A pneumatic radial tire for high-speed heavy loads, characterized in that it has a thin rubber squeegee sandwiched in a region near both width ends of the belt.