JPH0648113A - Pneumatic radial tire - Google Patents

Abstract

PURPOSE:To reduce the rolling resistance of a pneumatic radial tire having an organic fiber reinforced layer covering nearly the whole width of a belt. CONSTITUTION:On the outer peripheral side of a belt 8, an organic fiber reinforcement layer 9 having the substantially equal width to the belt width is arranged, and at a side part division part 10 widthin a range of 15-30% of the width front each side edge position of the organic fiber reinforcement layer 9 and a residual center division 11, the product value of the strength per organic fiber cord and the number of count of cords is set larger in the center division part than that in the side part division part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic radial tire provided with an organic fiber reinforced layer covering a belt over substantially the entire width thereof, and more particularly, to reducing rolling resistance of the tire to reduce fuel consumption of a vehicle. Is.

[0002]

2. Description of the Related Art In order to reduce rolling resistance of tires,
Conventionally, it has been widely practiced to reduce the hysteresis loss of the tread rubber and reduce the weight of each component of the tire, but the tread portion is protected on the outer peripheral side of the belt against high speed rotation of the tire. It is said that the provision of such an organic fiber reinforcing layer causes an increase in tire weight, which is contrary to low fuel consumption. Therefore, the prior art has not made an attempt to reduce the fuel consumption of a tire including such an organic fiber reinforcing layer.

[0003]

However, in recent years, in order to improve the high-speed durability of pneumatic tires for passenger cars in particular, an organic fiber reinforced layer having a width substantially equal to the belt width is provided on the outer peripheral side of the belt. Various types of tires have been proposed, and this type of tire also
It is strongly desired to reduce fuel consumption.

The present invention has been made in order to meet such requirements, and even if an organic fiber reinforced layer having a width substantially equal to the belt width is provided in order to enhance the high speed durability of the tie, the rolling resistance of the tire is still maintained. By providing a pneumatic radial tire that can effectively reduce fuel consumption.

[0005]

In the present invention, the rolling resistance RR of a tire is generally expressed as RR = Σσεtan δdV where σ: stress ε: strain tan δ: losttangent dV: volume. In addition, while paying attention to the deformation mode of the belt when Taya rolls,
Deformation of the belt during rolling of the tire is based on the knowledge that the belt is in a constant stress state (constant σ) in its central area and in a constant strain state (ε constant) in its side areas, and , By reducing the strain (ε), in other words, by increasing the rigidity to reduce the amount of deformation, and by reducing the stress (σ) in the belt side area, in other words, lowering the rigidity. By suppressing the generation of force, the rolling resistance of each of these areas is reduced together.

For this reason, in the pneumatic radial tire of the present invention, the organic fiber reinforcing layer having a width substantially equal to the belt width is provided on the outer peripheral side of the belt layer. Calculate the product of the strength per organic fiber cord to be formed and the number of cords to be driven, from the side edge portion of each side of the organic fiber reinforcing layer to the side area portion within the range of 15 to 30% of the width. Smaller than that in the central area of the rest.

[0007]

In this pneumatic radial tie, the central portion of the belt in the width direction is more firmly suppressed by the organic fiber reinforcing layer, and as a result, the interlayer strain of the belt layer during rolling of the tire is suppressed. Since it is reduced, the rolling resistance of the central portion is effectively reduced.

On the other hand, the restraining force of the strain between the belt layers at the side end portions of the belt by the organic fiber reinforcing layer becomes relatively small, and therefore the stress generated due to the interlayer strain also becomes small. The rolling resistance of its side edge will also be effectively reduced. Thus, here, the rolling resistance is reduced over the entire width of the belt, so that the fuel consumption of the tire as a whole is improved.

[0009] By the way, in this tire, the product of the cord strength per cord and the number of cords to be corded is determined to be 15 to 30% of the width of the organic fiber reinforced layer, and the remaining central region. By changing the part and the part, the above-described effects can be made more remarkable. That is, if it is less than 15%, the rolling resistance reducing effect on the side end portion of the belt is small, and if it exceeds 30%, the reducing effect on the belt central portion is small.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view in the tread width direction showing an embodiment of the present invention, in which 1 is a tread portion, 2 is a pair of sidewall portions continuous with the tread portion 1, and 3 is each side. Each bead portion connected to the wall portion 2 is shown.

Here, substantially in the tire circumferential direction
A radial carcass 4 consisting of one ply of a cord extending at an angle of 90 ° is arranged, and each side end portion of the radial carcass 4 is folded around the bead core 5 from the inside to the outside of the tire and wound up, On the outer circumferential side of the crown portion of the radial carcass 4, two belt layers 6 and 7 each of which extends from the tread circumferential direction at a relatively small angle and intersects with each other are arranged to form a belt. 8

Further, here, on the outer peripheral side of the belt 8,
Organic fiber reinforced layer 9 having a width substantially equal to the belt width
To arrange. The organic fiber reinforcing layer 9 is formed by, for example, spirally winding a strip ribbon formed by rubber-coating a plurality of organic fiber cords extending in parallel with each other on the outer peripheral side of the belt 8. From the respective side edge positions of the organic fiber reinforcing layer 9 here, in the side area portion 10 within the range of 15 to 30% of the width, the strength per one organic fiber cord is The value of the product with the number of imprinted cords is made smaller than the value of the similar product of the remaining central area portion 11 of the organic fiber reinforcing layer 9. 12 in the figure
The inner liner as the innermost layer of the tire is shown.

According to the tire constructed as described above, the interlayer strain of the belt 8 is reduced by the central area portion 11 of the organic fiber reinforced layer 9 and the side area portion 10 of the belt 8 is used. By reducing the stress generated due to the inter-layer strain of (1), as described above, the rolling resistance can be effectively reduced, and the fuel consumption can be reduced.

By the way, according to the present invention, in addition to the above, in addition to the organic fiber reinforced layer 9, the side end portion and / or the central portion of the belt 8 are related to the performance required for the tire. It is also possible to dispose a reinforcing layer composed of an organic fiber cord (not shown), which is a single layer or a plurality of layers which are overlapped with each other.
It extends substantially in the circumferential direction of the tread.

Further, in this tire, an interposing rubber having a width substantially equal to the belt width, preferably having a thickness of 0.5 to 1.5 mm is arranged between the respective belt layers 6 and 7, and the interposing rubber is used. The side edge rubber portion of the rubber in the range of 15 to 30% of the belt width is made of a softer rubber than the coating rubber of the belt layers 6 and 7, and the central rubber portion excluding the side edge rubber portion is made the belt layer 6 , 7 are made of rubbers harder than the coating rubbers, the interlayer strain in the central portion of the belt 8 is further reduced, and the stress generated at the side end portions of the belt 8 is further reduced to reduce the rolling resistance of the tire. Can be further reduced.

COMPARATIVE EXAMPLE A comparative test regarding rolling resistance between the invention tire and the comparative tire will be described below. ◎ Test tire A tire with a size of 205/65 R 15 was assembled on a rim of 6 1/2 J × 15 and filled with an internal pressure of 2.0 kg / cm ² . Inventive Tire 1 A tire having the structure shown in FIG. 1, in which the belt cords are 1 × 5 steel cords, the angle of these cords with respect to the circumferential direction of the tread is 20 °, and the organic fiber reinforcing layer is also used. Side area part for the entire width of 9
The width of 10 is 25%, the organic warfare code forming the side area part 10 is a 840d / 2 nylon code, the central area part 11
The 1260d / 2 nylon cord is used as the organic fiber cord that forms the. Here, the strength per 840d / 2 nylon cord is 14kgf, and the similar strength of the 1260d / 2 nylon cord is 22kgf. The number of cords to be impressed in each of the side area portion 10 and the central area portion 11 was the same.

Comparative tire 1 In the place shown in FIG. 1, the entire organic fiber reinforced layer was
Other than the 1260d / 2 nylon cord, the tire was the same as the invention tire 1 including the number of nylon cords to be driven.

Inventive Tire 2 As shown in FIG. 2, in addition to the organic fiber reinforcing layer 9, a belt 8
Where the other reinforcing layer 21 covering the side end portion of the tire is arranged, the structure of the organic fiber reinforcing layer 9 is made the same as that of the invention tire 1, and the structure of the reinforcing layer 21 is changed to the side area portion 10.
The same tire as that of. The other parts are the same as those of the invention tire 1.

Comparative tire 2 As shown in FIG. 2, a tire in which each of the organic fiber reinforcing layer 9 and the reinforcing layer 21 is composed of a nylon cord of 1260 d / 2. Here, the number of cords to be driven is the invention tire 1
Is the same as

Inventive Tire 3 As shown in FIG. 3, in addition to the organic fiber reinforcing layer 9, another reinforcing layer 21 for covering the side end portions of the belt 8 is arranged, and both of them are 840d / 2. Made of nylon cords, and the number of cords in the central area 11 is 70/5 cm,
A tire in which the number of cords driven into the side area portion 10 and the reinforcing layer 21 is 60/5 cm. Others are the same as the invention tire 1.

Comparative tire 3 As shown in FIG. 3, a tire in which the cords of the organic fiber reinforcing layer 9 and the reinforcing layer 21 are both 65 cords / 5 cm. The cord was a 840d / 2 nylon cord.

Inventive Tire 4 As shown in FIG. 4, in addition to the organic fiber reinforcing layer 9, a reinforcing layer 22 having the same width as that of the organic fiber reinforcing layer 9 is provided, and both layers 9 and 22 are
A tire having the same structure as the invention tire 1.

Comparative tire 4 A tire in which the fiber cords of both layers 9 and 22 are nylon cords of 1260d / 2 as shown in FIG.

Inventive Tire 5 As shown in FIG. 5, in addition to the organic fiber reinforcing layer 9, a reinforcing layer 22 having the same width as that of the organic fiber reinforcing layer 9 is provided, and both layers 9 and 22 are
A tire having the same structure as the invention tire 3.

Comparative tire 5 A tire in which the number of fiber cords in both layers 9 and 22 was 65 cm / 5 cm as shown in FIG. Code is 84
It was a nylon cord of 0d / 2.

◎ Test method Under the action of 400 kg load, 0-18 on a test drum having a steel smooth surface, a diameter of 1707.6 mm and a width of 350 mm.
The rolling resistance of the tire when rolling at a speed of 0 km / h was measured by the coasting method and evaluated.

◎ Test Results The test results are shown in Table 1 with indexes. The larger the index value, the better the result.

[0028]

[Table 1]

From Table 1, it is clear that any of the invention tires can effectively reduce rolling resistance as compared to the comparative tire.

[0030]

As is apparent from the above comparative example, according to the present invention, the product of the strength per organic fiber cord and the number of driven cords in the organic fiber reinforcing layer having a width substantially equal to that of the belt. By making the central area portion thereof larger than the side area portion thereof, the rolling resistance of the tire can be reduced and the fuel consumption can be effectively improved.

[Brief description of drawings]

FIG. 1 is a sectional view in a tread width direction showing an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an arrangement example of an organic fiber reinforcing layer and a reinforcing layer.

FIG. 3 is a schematic diagram showing another arrangement example of an organic fiber reinforcing layer and a reinforcing layer.

FIG. 4 is a schematic diagram showing still another arrangement example of an organic fiber reinforcing layer and a reinforcing layer.

FIG. 5 is a schematic diagram showing a further arrangement example of an organic fiber reinforcing layer and a reinforcing layer.

[Explanation of symbols]

 1 Tread Part 2 Sidewall Part 3 Bead Part 4 Radial Carcass 6,7 Belt Layer 8 Belt 9 Organic Fiber Reinforcing Layer 10 Side Area Part 11 Central Area Part

Claims (1)

[Claims] 1. A radial carcass comprising a tread portion, a pair of sidewall portions connected to the tread portion, and a bead portion continuous with each sidewall portion, and a radial carcass comprising at least one carcass ply, and the radial carcass. A belt formed of at least two belt layers each of which is arranged on the outer peripheral side of the crown portion of the carcass and extends at a relatively small angle to the tread circumferential direction and intersects with each other. A pneumatic radial tire, wherein an organic fiber reinforcing layer having a width substantially equal to the belt width is arranged on the outer peripheral side of the belt, and the width of the organic fiber reinforcing layer is increased from each side edge position to 15 The value of the product of the strength per one organic fiber cord and the number of cords impressed in the central zone portion in the side zone portion within the range of -30% and the remaining central zone portion A pneumatic radial tire comprising greater than section area portion.