JPH03121907A - Heavy load tire - Google Patents

Abstract

PURPOSE:To prevent the separation of the ends of a belt and improve high speed durability at the heavy load tire for a bus or the like, by providing with a predetermined cord orientation a middle layer of an aromatic polyamide fibre cord between a carcass and a belt layer, and arranging so that its outer side end portions may be turned up toward the outside of the outer side belt ply. CONSTITUTION:A belt layer 9 is constituted with an outer side belt ply 11 whose cord angle against the equator CO is more than 10 deg. and less than 30 deg., and an inner side belt ply 12 which crosses this and has the same cord angle. And a middle layer 15 consisting of an aromatic polyamide fibre cord is provided between the inner side belt ply 12 and a carcass 7. The cord of this middle layer 15 has an inclination angle of more than 50 deg. and less than 70 deg. against the equator, and also is arranged in the same direction as the inner side belt ply 12. And turning up portions 17 are formed at both side end portions of the middle layer 15, and the outside ends of the outer side belt ply 12 are wrapped. As a result, the separation of the ends of the belt is prevented, and high speed durability can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a heavy-duty tire that can suppress belt edge peeling and improve high-speed durability.

[Conventional technology]

In the case of radial tires used for heavy-load vehicles such as trucks and buses, conventionally, as shown in FIG. A heald layer consisting of at least three belt braces b1, b2, and b3 is provided. The belt layers are arranged so that the cord angles of the radially outer belt bridles b1, b2, and b3 intersect with each other, and this mutually intersecting truss structure reinforces the tread portion uniformly and with high rigidity. ing.

[Problem to be solved by the invention]

However, it is known that when such a tire runs at high speed, so-called glabellar peeling, in which the outermost belt bridle b1 separates from its end, occurs at an early stage, significantly reducing high-speed durability.

This is because the tire is used under high load conditions, so the internal tread temperature is higher than that of interlayer tires, and because the belt layer is formed from cut-end braise, the adhesion to the surrounding rubber at the ply ends is strong. In addition, the binding force to the tire case is weak, and as a result, as the outer diameter of a portion of the tread shoulder increases, the ground contact pressure increases, causing the internal temperature in this area to further rise.

Moreover, since the belt layer is oriented so that the cords of bell 1 to b1, b2, and b3 intersect, when the tire deforms, the cords extend in different directions, and therefore
, b2, and b3, and this, together with the temperature rise at the shoulder portion, causes separation between the eyebrows from the end of the belt ply b1.

In addition, in order to prevent this kind of glabellar peeling, the tread rubber has been improved by adopting low heat generation rubber with a small loss coefficient for the tread rubber, and reducing the tread gauge thickness, especially in the shoulder area. Although some efforts have been made to reduce heat build-up, these measures are extremely ineffective; furthermore, the use of low heat build-up rubber reduces grip performance, and a decrease in gauge thickness impairs wear life. This causes many negative effects on tire performance, such as worsening uneven wear.

The present invention provides the following features: on both ends of the base interposed between the carcass and the second belt braai located inside the belt layer;
Basically, the intermediate layer is provided with a folded part that surrounds the outer end of the first belt braai located on the outer side and is folded back facing each other, thereby increasing the heat resistance at the end of the belt layer without impairing various tire performances. The purpose of the present invention is to provide a heavy-duty tire that can suppress peeling between belt briars and improve high-speed durability.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a carcass having a radial or semi-radial structure that folds around a bead core of a bead part from a tread part through a sidewall part, and a carcass having a radial direction outer side of the carcass and an inner part of the trend part. A belt layer consisting of two belt braais arranged on one side and using steel belt cords, and an intermediate layer having intermediate cords made of aromatic polyamide fibers arranged between the carcass and the belt layer. At the same time, the belt layer includes a first belt briar which is located on the outside in the radial direction of the belt briar and has belt cords arranged at an inclination angle of 10' or more and 30 degrees or less with respect to the tire equator; A second belt disposed inside the first belt britain and having heald cords arranged in a direction intersecting the belt cord of the first belt britain and at an inclination angle of 10" or more and 30 degrees or less with respect to the tire equator. The intermediate layer includes folded portions that are folded facing each other and surrounding the outer end of the first belt ply, at both end portions of the base interposed between the carcass and the second belt ply. and the intermediate cord is oriented at the base in the same direction as the belt cord of the second belt ply and 50 degrees relative to the tire equator.
This is a heavy-duty tire arranged at an inclination angle of 70 degrees or more and 70 degrees or less.

[Effect]

The intermediate layer disposed between the carcass and the belt layer is formed by an intermediate cord made of aromatic polyamide fibers, which has higher elongation than steel belt cords, so when the tire deforms, the carcass and the belt layer This relieves the shear stress acting between the two belt plies. In addition, since the outer ends of each of the first and second belt plies are covered by the folded portion,
Improves adhesion to rubber.

Moreover, since the inclinations of each belt cord of the first and second heald plies and the intermediate cord of the intermediate layer are regulated within a specific range, the intermediate cord cooperates with the belt cord of each heald ply at the base of the intermediate layer to create a truss. Forms a structure and exerts a hoop effect. Further, in the folded portion of the intermediate layer, the intermediate cord is inclined in a direction opposite to the base, thereby forming a truss structure different from that of the base. Therefore, at the outer end of the belt layer, a truss structure is formed in which the inner and outer surfaces of the belt layer have different shapes.
The double truss structure strongly reinforces the outer edge of the belt layer, suppressing the increase in ground pressure associated with the growth of the outer diameter at the tread shoulder and suppressing the temperature rise in this area.

〔Example〕

An embodiment of the present invention will be described below based on the drawings.

In the figure, a heavy-duty tire 1 includes a bead portion 3 through which a bead core 2 passes, a sidewall portion 4 that is continuous with the bead portion 3 and extends outward in the tire radial direction, and a tread that connects the outer ends of the sidewall portion 4. Part 5.

Further, between the bead portions 3.3, a carcass 7, which is obtained by folding the bead core 2 from the inside to the outside, is passed from the tread portion 5 to the sidewall portion 4 to the bead portion 3 at both ends of the main body portion 7A. At the same time, a belt layer 9 is provided on the outside of the carcass 7 in the radial direction and inside the trend portion 5 in the circumferential direction of the tire.

The carcass 7 has a radial or semi-radial structure consisting of one or more carcass plies in which carcass cords are arranged at an angle of 70 to 90' with respect to the tire equator.

Naori - Cascords include organic and inorganic fiber cords,
In this example, steel cord is used. Also, the carcass 7
A bead apex 10 made of hard rubber and having a triangular cross section and extending radially outward from the bead core 2 with a gradually decreasing thickness is provided at the opening of the main body portion 7A and the folded portions 7B at both ends thereof. The sidewall portion 4 is reinforced to increase the tire's lateral rigidity.

Further, in this example, the bell l-11!9 is the first belt ply 11 disposed facing the carcass 7G from the trend surface.
, a second belt ply 12 has a two-layer structure, and the width of the second belt ply 12 is larger than the width S of the first belt ply 1], and the width of the second belt ply 12 is larger than the width S of the first belt ply 1. BW, that is, in this example, by setting the width of the second belt fly 12 to 0.83 times or more and 0.99 times or less of the trend width TW, the belt layer 9 can cause the tread portion 5 to have a hoop effect almost entirely in its entirety. It has and reinforces it.

The first and second belt plies 11 and 12 are each formed from a strong steel belt cord having an initial elastic modulus of 15 x 10'kg/am" or more, and the second belt ply 12 are arranged upward to the right at an angle β2 of 10 to 30'' with respect to the tire equator CO, while the first belt ply 11 arranges its belt cord upward to the left at an angle β1 of 10 to 306 with respect to the tire equator CO. are doing. Accordingly, the belt layer 9 is formed in each belt ply 11 .
Twelve belt cords cross each other.

The intermediate layer 15 is arranged at both ends of a base part 16 disposed between the carcass 7 and the second belt ply 12 in the trend part 5, surrounding the outer end of the first belt ply 11 and facing inward. It has a hold end shape with a pair of folded parts 17.107 facing each other.

The intermediate layer 15 is made of an organic fiber cord that has low elasticity and relatively high extensibility as well as excellent heat resistance compared to the steel belt cord, that is, an organic fiber cord with an initial elastic modulus of 13 x 10.
It is formed by an intermediate cord using an aromatic polyamide fiber having a weight of 11"kgf/cl11" or less, and the intermediate cord has an angle of 50 degrees or more and 70 degrees upward to the right or upward to the left in this embodiment with respect to the tire equator CO at the base 16. Therefore, the folded portion 17 is tilted in the opposite direction to the base portion 16 by the same angle β2 as the base portion 16 with respect to the tire equator CO.

Next, the belt cord 11d of the first belt ply 11, the belt cord 12d of the second belt ply 12, and the intermediate layer 1
The truss structure formed by the intermediate cord 15d of No. 5 will be described.

On the base 16 side, the intermediate cord 15d is inclined upward to the right as shown in FIG. As shown in Part 3), the intermediate cord 15d is inclined upward to the left in the opposite direction to the base 16 side.

Therefore, in the folded portion 17, l laths shown by triangles A2, B2, and C2, which are different from the base portion 16, are formed.

In this way, two different truss structures are formed at the outer end of the belt layer 9, sandwiching the outer end of the belt layer 9, so this double truss structure reduces the hoop effect at the outer end of the belt layer 9. It makes it powerful. Also, first,
By setting the inclination of each belt cord of the second belt ply 11, 12 and the inclination of the intermediate cord of the intermediate layer 15 within the above-mentioned inclination angle ranges, each truss structure of the base 16 side and the 17 folded portions is By forming both shapes substantially close to equilateral triangles, the hoop effect can be further enhanced. As a result, the restraining force on the tire case at the outer end of the first belt ply 11 can be increased, and temperature rise and uneven wear caused by outer diameter growth at the tread shoulder portion can be suppressed.

1 2 Also, since the intermediate layer 15 covers and protects the outer ends of the belt layer 9, it is possible to use steel cords with cut ends for the first and second belt plies 11 and 12. .

Further, in this embodiment, the folded portion 17 has an overlapping portion 19 where the folded portion 17 overlaps the first belt ply 11.
The length l is in the range of 5 cm or more and 15 cm or less.

If the length l of the overlapping portion 19 is 5 cm or less, the restraining force at the outer end of the belt layer 9 will be insufficient, whereas even if the length l is 15 cm or more, the restraining force will remain approximately constant without increasing. becomes.

If other organic fiber cords such as nylon, rayon, polyester, etc. are used as the intermediate cord, the binding force of the tire case will be insufficient, the growth of the outer diameter cannot be suppressed, and the heat resistance will be poor.

Further, as the intermediate cord, one having a cord size of 1500 d/2 and a number of twists of 35×35 turns/10 cm can be suitably used.

Also, as a base rubber, 100% modulus (Mloo)
25-50kg/cln2 and 300% modulus (
M2O3) is 100 to 200 ktr/a11", JISA hardness (HA) is 75 to 80", and complex modulus of elasticity (El) is 50 to 200 kf/cI11
It is preferable to use a soft rubber composition with low heat generation and a loss coefficient (tan δ) in the range of 0.1 to 0°2, thereby further reducing the shear strain. At the same time, the middle layer 15 and the second
separation between the belt ply 12 and the belt ply 12 can be prevented.

The complex modulus of elasticity (El) and loss coefficient (tanδ) are
70℃ using a viscosity spectrometer manufactured by Oiki Seisakusho.
Under the conditions of frequency 20H2, static strain rate 10%, dynamic strain rate 2%,
This is a value measured using a strip-shaped sample of 4 days x 30 m length Xl and 5 m thickness.

〔Concrete example〕

It has the structure shown in Figure 1, and the tire size is 11R22.
A prototype tire with 514P and HWJ tread pattern was manufactured, and its high-speed durability was tested using a drum running test machine. A conventional tire shown in Fig. 344 was also prototyped and comparative tests were conducted.

The test was carried out at a load of 140% of the standard load and at a speed of 110%.
Starting at 0 km/h, the speed was stepped up to 10 km/h every 2 hours, and the belt edge breaking temperature at the time belt breakage occurred in the sample tire was measured and expressed as an index with the conventional product set at 100.

As a result of the test, when the conventional product was set as 100, the product according to the present invention was 112, and it was found that the heat resistance durability of the example was improved by 12% compared to the conventional product.

〔Effect of the invention〕

The heavy-duty tire of the present invention, such as a ridged tire, includes an intermediate layer having folded portions at both ends of the base interposed between the carcass and the belt layer, which are folded back to face each other and surround the outer edge of the belt layer. At the same time, since the inclinations of each cord of the two belt plies of the belt layer and the intermediate cord of the intermediate layer are respectively regulated, a truss having different shapes, which are the inner and outer surfaces of the belt layer, is formed at the outer end of the belt layer. The outer edge of the bell 1 layer is strongly reinforced by the double truss structure, which reduces the occurrence of belt ply separation and suppresses the increase in ground pressure associated with the growth of the outer diameter at the tread shoulder. As a result of being able to suppress the temperature rise in this area, high-speed durability can be greatly improved without impairing various tire performances.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a plan view showing the belt layer developed, and FIG. It is a cross-sectional view showing the technology. 2-. Bead core, 3-. Bead portion, 4- Sidewall portion, 5-. Tread portion, 7- Carcass, 9
- Belt layer, 11- First belt ply, 12-.- Second belt ply, 15- Intermediate layer, 16-.- Base, 17- Turned part, CO- Tire equator.

Claims (1)

[Scope of Claims] 1. A carcass having a radial or semi-radial structure that folds around a bead core of a bead portion from a tread portion through a sidewall portion, and a carcass arranged radially outside the carcass and inside the tread portion. It has a belt layer consisting of two belt plies using steel belt cords, and an intermediate layer in which intermediate cords made of aromatic polyamide fibers are arranged between the carcass and the belt layer. ,
The belt layer includes a first belt ply located on the outside in the radial direction among the belt plies and having belt cords arranged at an inclination angle of 10° or more and 30° or less with respect to the tire equator, and the first belt ply. and a second belt ply arranged inside the belt ply and having belt cords arranged in a direction intersecting with the belt cords of the first belt ply and at an inclination angle of 10° or more and 30° or less with respect to the tire equator. On the other hand, the intermediate layer is provided with folded portions on both side end portions of the base portion interposed between the carcass and the second belt ply, and which are folded back to face each other surrounding the outer end of the first belt ply; The intermediate cord is arranged at the base in the same direction as the belt cord of the second belt ply and at an inclination angle of 50 degrees or more and 70 degrees or less with respect to the tire equator. 2 The intermediate layer is made of aromatic polyamide fiber, has a cord size of 1500 d/2, and has a twist number of 35 x 35.
2. The heavy-duty tire according to claim 1, characterized in that the intermediate cords are arranged at a rotation speed of 10 cm. 3 In the intermediate layer, the folded portion has a length (l) of the overlapping portion overlapping with the first belt ply of 5 cm or more and 15 cm.
The heavy-duty tire according to claim 1 or 2, characterized in that the tire diameter is less than or equal to m. 4 The intermediate cord of the intermediate layer has a 100% modulus of 25 or more and 50 kg/cm^2 or less, a 300% modulus of 100 or more and 200 kg/cm^2 or less, and a JISA hardness of 75° or more and 80° or less. and has a complex modulus of 50 or more and 200 kg/cm
Claims 1 to 3 characterized in that the rubber composition is embedded in a rubber composition having a loss coefficient of ^2 or less and a loss coefficient of 0.1 or more and 0.2 or less.
Heavy-duty tires described in any of the above.