JPH01122705A - Flat radial tire - Google Patents

Abstract

PURPOSE:To prevent both uneven wear and separation of a belt end by disposing a reinforcing layer between a belt layer and a carcass layer, and by arranging both reinforcing layers located on both sides of the reinforcing layer, between specific inner and outer positions in the tread width. CONSTITUTION:A tire 1 is composed of a carcass layer 2, a tread 7, a belt layer and the like. In this arrangement, a reinforcing layer 11 composed of less than two reinforcing plies 12 in which cords are embedded substantially in parallel with the equator plane 5 of the tire is disposed between a belt ply 9 in the belt layer 8 and the carcass layer 2. At least one layer of a reinforcing ply 12 is formed of a plurality of reinforcing plies 14, 15 disposed on both sides of the equator plane 5 of the tire. Further, the reinforcing plies 14, 15 are located between outside points 18, 19 distant from both side shoulder ends 16, 17 of a tire 1 by one-seventh of the tread width W and inside points 20, 21 distant form the equator plane 5 of the tire by one-tenth of the tread width.

Description

[Detailed description of the invention]

- This invention relates to a flat radial tire having an aspect ratio of 0.85 or less.

In general, flat radial tires with an aspect ratio of 0.85 or less are affected by various effects due to internal pressure filling and ground contact deformation during load transfer, but two of the most significant effects are shoulder edge Uneven wear due to large diameter growth at a point approximately 174 tread widths away from
There is shoulder drop and belt end separation based on interply shear forces at the belt ends. Conventionally, in order to eliminate the above-mentioned influence, a flat radial tire as described in Japanese Patent Application Laid-Open No. 80-22504 has been proposed. This product has reinforcing bands in which cords with cord angles of 5 degrees or less are embedded on both sides of the belt center on the radial outside of the belt layer, and each reinforcing band is connected to the distance from the center of the belt to the end of the belt. When L, the distance from the center of the belt to the inner edge of the reinforcing band is 0.2L ~
0.4L, and the distance from the center of the belt to the outer edge of the reinforcing band is within the range of 0.7L to 0.8L. However, in flat radial tires like this, the area where the diameter grows greatly is reliably restrained and the amount of growth is made uniform over the entire width, so the former, that is, uneven wear, is reliably prevented. However, with regard to the latter, that is, belt end separation, the only effect is to reduce the ground contact pressure in the center area in the width direction of the tread by making the growth amount uniform, and to reduce the amount of heat generated by the tread. However, there was a problem in that it was not possible to reduce the inter-ply shear force at the end of the belt during tire load transfer, and it was not possible to effectively prevent this. . - These problems are caused by a carcass layer consisting of at least one carcass ply in which cords extending substantially in the radial direction are embedded, a tread arranged radially outward of the carcass layer, and a connection between the carcass layer and the tread. and a belt layer consisting of at least two belt plies in which cords are embedded intersecting at an angle of 10 degrees to 40 degrees with respect to the tire equatorial plane, and the aspect ratio is 078.
Reinforcement consisting of two or fewer layers of reinforcing plies in which a cord substantially parallel to the tire equatorial plane is embedded between the belt ply located at the outermost radial direction and the carcass layer, in a flat radial tire of 5 or less. and at least one layer of reinforcing ply is composed of first and second reinforcing plies arranged on both sides of the tire equatorial plane, and these first and second reinforcing plies are arranged from the shoulder end of the tire. This can be solved by locating the points between the outer points, which are each separated by 177 degrees of the tread width, and the inner points, which are each separated by 171 degrees of the tread width from the tire equatorial plane. January First, in the present invention, the 18th and 2nd reinforcing plies, which are placed on both sides of the tire's equatorial plane, are connected to an outer point that is 1/7 of the tread width away from the shoulder edge of the tire, and from the tire's equator plane to the tread. Since they are located between the inner points separated by 1110 mm of the width, the area where the diameter grows the most during internal pressure filling is restrained by the first and second reinforcing plies that hardly elongate, and the tire's The amount of growth is substantially uniform over the entire width, and occurrence of uneven wear is reliably prevented. Furthermore, in order to effectively reduce the inter-ply shearing force at the belt end during load transfer and prevent belt end separation, the present invention provides first and second
The reinforcing ply is placed between the radially outermost belt ply and the carcass layer. As a result,
When the tire undergoes ground contact deformation due to load transfer, the circumferential lengths of the first and second reinforcing plies hardly change. A directional compressive force acts. This significantly reduces the inter-ply shear forces at the belt ends and reliably prevents belt end separation from occurring. 1 Presentation 1 Hereinafter, one embodiment of the present invention will be described based on the drawings. In FIG. 1.2, l is a flat radial tire, and this tire l has an aspect ratio, that is, a value obtained by dividing the tire height by the tire width, of 0.85 or less. The tire 1 has a toroidal carcass layer 2, and the carcass layer 2 consists of at least one carcass ply 3, in this example one layer. A large number of reinforcing cords 4 made of steel or the like are buried inside each carcass ply 3, and these cords 4 extend substantially in the radial direction, that is, in a direction substantially orthogonal to the tire equatorial plane 5. Both end portions of the carcass layer 2 are folded back around a ring-shaped bead 6. Reference numeral 7 denotes an annular tread disposed on the radially outer side of the carcass layer 2, and an annular belt layer 8 is disposed between the tread 7 and the carcass layer 2. This belt layer 8 consists of at least two layers, in this embodiment two layers of belt plies 9, and a large number of reinforcing cords 10 made of steel or the like are embedded inside each of these belt plies 9. The inclination directions of these cords 10 are opposite to each other with respect to the tire equatorial plane 5 for each belt ply 9, that is, they intersect with the tire equatorial plane 5 in between. The intersecting angles of these cords 10 with respect to the tire equatorial plane 5 are within the range of 10 degrees to 40 degrees. Reference numeral 11 denotes a reinforcing layer consisting of two or less reinforcing ply layers 12, in this example one layer, and within each reinforcing ply 12, cords 13 substantially parallel to the tire equatorial plane 5 are arranged spirally or in parallel. It is buried. As a result, the reinforcing layer 11 has a strong hoop tightening effect. The reason why the reinforcing layer 11 is composed of two or less reinforcing plies 12 is that the reinforcing ply 12
This is because if there are three or more layers, the total gauge of the tread 7, belt layer 8, and reinforcing layer 11 becomes thick, which is harmful from a heat generation standpoint. Further, the reinforcing ply 12 of the reinforcing layer 11
Among them, at least one layer of reinforcing ply 12 is composed of a first reinforcing ply 14 and a second reinforcing ply 15 arranged on both sides of the tire equatorial plane 5, respectively. Therefore, when the reinforcing layer 11 is composed of 2M reinforcing plies 12, the remaining one reinforcing ply 12 may be continuous in the width direction, and the first and second reinforcing plies 14, 15 are outer points 1 that are 1/7 of the tread width W from both shoulder edges 1B and 17 of tire 1.
day, 1θ, and 1/1 of the tread width W from the tire equatorial plane 5
The reason for this is that these first and second reinforcing braces 14 and 15 are located between the outer points 1 and 19 in the width direction. If the tread is extended, it will be necessary to reinforce parts that do not need to suppress radial growth, which will make it impossible to achieve uniform diametric growth over the entire tread width, and the shoulder portions 22 and 23 will have uneven radial growth. This is because uneven wear such as reduction and shoulder drop occurs, and on the other hand, these first and second reinforcing plies 14
．． If the tire 15 extends inward in the width direction from the inner point 20.21, the diameter of the tire 1 will grow unevenly during internal pressure filling, as described above, and a part of the center 24 will have river wear. This is because uneven wear occurs. Note that the first
, the width M of the second reinforcing ply 14.15 is the tread width W.
The ratio is preferably 1/8 or more, because if it is less than the above number, the effect of preventing uneven wear and the effect of suppressing belt end separation will not be sufficient. Here, shoulder end te of tire 1, 17 and tread width W
are synonymous with the ground contact edge and ground contact width on the meridian cross section when the tire 1 is filled with a normal internal pressure and a normal load is applied. Since the first and second reinforcing plies 14 and 15, which have a strong hoop tightening effect, are provided at the positions as described above, the flat radial tire l grows most in diameter when filling with internal pressure, that is, at the shoulder end. The vicinity of a point located one pigeon tread width away from 1B and 17 is restrained by the first and second reinforcing plies 14 and 15 that hardly cause expansion,
The amount of growth of the tire 1 is substantially uniform over the entire width, and occurrence of uneven wear is reliably prevented. Further, the first and second reinforcing plies 14 , 15 are arranged between the radially outermost belt ply 8 of the belt layer 8 and the carcass layer 2 . Here, the circumferential displacement of each belt ply 8 on the tire equatorial plane 5 will be considered with reference to FIGS. 3(a) and 3(b). 3(a) and 3(b) show a circumferential cross-section of the region where the reinforcing layer 11 of the tire 1 exists, taken parallel to the tire equatorial plane 5, and show a state in which the left half has been deformed on contact with the ground due to load transfer. , the right half shows the free state. First, when the reinforcing ply 12 is arranged radially outward of the belt layer 8 as shown in FIG. 3(a), one circumference of the belt layer 8 is shorter than one circumference of the reinforcing ply 12, and Since the circumferential length of the reinforcing ply 12 hardly changes even with deformation, when the belt layer 8 and the reinforcing ply 12 are subjected to a circumferential bending force P as shown by the arrow due to contact with the ground and are deformed flat,
The belt layer 8 is stretched by the reinforcing ply 12. - On the other hand, as shown in FIG. 3(b), the reinforcing ply 12 is attached to the radially outermost belt ply of the belt layer 8.
9, in this case between the belt layer 8 and the carcass layer 2, when the belt layer 8 and the reinforcing ply 12 are deformed flat by receiving the circumferential bending force P due to contact with the ground,
The belt plies 8 outside the reinforcing ply 12 are compressed by the reinforcing ply 12, contrary to the above description. In this way, the reinforcing ply 12, that is, the first and second reinforcing ply 14
．． 15 as the radially outermost belt ply of belt layer 8
and the carcass layer 2, the first. Second
The compressive force is applied to the widthwise side ends of the belt plies 8 that are radially outward from the reinforcing plies 14, 15, and the shearing force at the belt ends is suppressed, thereby reliably preventing belt end separation. Since such an effect becomes larger as the first and second reinforcing plies 14.15 are located radially inward, the first and second reinforcing plies 14.15 are applied to all belt plies as in this embodiment. 3, that is, it is preferable to arrange it between the belt layer 8 and the carcass layer 2. Also, the sum of the elastic modulus in the cord direction per unit width of each reinforcing ply 12 is the elastic modulus in the cord direction per unit width of the belt ply 9. It is preferably within the range of 10% to 35% of the sum of the ratios. The reason for this is that if it is less than 10%, the effect of suppressing diameter expansion during internal pressure filling cannot be expected, and the effect of reducing the shear force between the plies at the belt end during load transfer is also small, so the belt end separation resistance On the other hand, if it exceeds 35%,
This is because the tension shared by the reinforcing layer 11 with respect to the belt layer 8 becomes large, and the ability to follow road surface protrusions in particular becomes poor, which may lead to the reinforcing ply 12 breaking. The cord 13 of the reinforcing ply 12 is made of extensible steel cord, aromatic polyamide fiber, or the like. Next, a first test example will be explained. At the beginning of this test, a comparison tire l whose size is 11/70R22.5
, Test Tire 1, and Test Tire 2 were prepared. As shown in FIG. 4(a), the comparative tire I has the first and second reinforcing plies C and D disposed on the radially outer side of the belt layer B, and the first and second reinforcing plies C and D are arranged radially outward from the shoulder end S of the tire. The distance Q from the width direction outer edge of the second reinforcing ply C, D is 19% of the tread width W, and from the tire equatorial plane E to the width direction inner edge of the first and second reinforcing ply C, D. The first and second reinforcing plies C are arranged so that the distance R is 13% of the tread width W.
, D are arranged. On the other hand, the test tire 1 is shown in Fig. 4 (b
), a reinforcing layer 11 consisting of first and second reinforcing plies 14.15 is arranged between the belt layer 8 and the carcass layer 2, and a reinforcing layer 11 consisting of first and second reinforcing plies 14.15 is disposed between the belt layer 8 and the carcass layer 2, and from the shoulder end 18. Distance Q to the outer edge of the circle in the width direction of the second reinforcing ply 14.15
19% of the tread width W, and from the tire equatorial plane 5. The first and second reinforcing plies 14.15 are arranged so that the distance R to the inner end in the width direction of the second reinforcing ply 14.15 is 13% of the tread width W. Furthermore, as shown in FIG. 4(C), the test tire 2 has first and second reinforcing plies 14 between the belt layer 8 and the carcass layer 2.
In addition to arranging the inner reinforcing ply 31 consisting of 15 pieces,
An outer reinforcing ply 32 continuous in the width direction is disposed between the inner reinforcing ply 31 and the belt layer 8. In this test tire 2, the shoulder end 16
．． The distance #Q from the tire equatorial plane 5 to the outer edge of the circle in the width direction of the first and second reinforcing plies 14 and 15 is 18% of the tread width W.
．． These 1st. Second reinforcing ply 14.
15, and the outer reinforcing ply 32 is arranged so that the distance T from the shoulder end 113.17 to the outer end of the outer reinforcing ply 32 in the width direction is 21% of the tread width W.
are placed. In addition, the specifications of each other tire are shown in Attached Table 1.
2. Each of these tires is a 2-D-4 type (the front wheel has one axle, the rear wheel has two axles, and one of the rear axles is a drive shaft, and each rear wheel axle has four wheels. After installing it on the front wheel of a flat body truck of the type (model) equipped with tires, fill it with an internal pressure of 8.0Kg/Cm'' to 100%.
At the load rate of 70% on paved highways and 3% on paved general roads.
After running for 100,000 km on a 0% road, the belt ply of each tire was peeled off and the length of the crack at the end of the belt was measured. Assuming that the comparative tire 1 has an index display of 100, the test tire 1 has an index display of 7.
B. Test tire 2 had an index of 62, indicating that the crack length at the belt end could be sufficiently reduced. In addition,
When the outer reinforcing ply 32 is provided as in the test tire 2,
Shearing force at the belt ends during load transfer is further suppressed, improving belt end separation resistance. Here, the crack length of the comparative tire 1 was actually 6.0 mm. Next, a second test example will be explained. In this test, the distance Q was 11% (less than 1/7W) and R was 13% (1/7W).
Comparative tires that are (IOW or higher) 2. The distance Q is 19
% (1/7W or more), R is 8% (1/IOW not W4) and comparative tire 3 has the pressure 1111Q of 19% (1/IOW).
The above-mentioned test tire 1 having an R of 13% (1/IOW or more) and an R of 13% (1/IOW or more) was prepared and run under the same conditions as the first test example. In addition, other tire specifications are for test tire 1.
It is similar to After running, the amount of shoulder drop was measured in the same manner as described above, and the comparison tire 2 had an index of 100, and the sample tire 1 had an index of 31. In addition,
The index display of 100 is 3.8 ■ intestines. On the other hand, when the tread center portion 24 was inspected after driving, it was found that the comparative tire 3
In contrast, river wear with a width of 3.0 mm and a depth of 1.2 mm occurred, whereas such uneven wear was not observed in the test tire 1. In this way, the distance Q,
When R is 1/7W and 1/IOW, respectively, uneven wear is sufficiently reduced. Next, a third test example will be explained. In this test, the value obtained by dividing the sum of the elastic modulus in the cord direction per unit width of the reinforcing ply 12 by the sum of the elastic modulus in the cord direction per unit width of the belt ply S is 7% (10% or less). A comparison tire 4.
A test tire 3 of 14% (within the range of 10% to 35%) was prepared and run under the same conditions as the first test example. Note that other tire specifications are the same as those of test tire 1. After running, the crack length at the belt end was measured in the same manner as described above, and the comparative tire 4 had an index of 100, and the sample tire 3 had an index of 83. In addition,
Index-Display 100 is 5.8 ■. In this way, when the divided value is 105 or more, belt end separation can be reliably prevented. [Moxibustion] JL Maru] As explained above, according to the present invention, belt end separation can be reliably prevented without causing uneven wear.

[Brief Description of the Drawings] Fig. 1 is a meridian sectional view of a tire showing an embodiment of the present invention, Fig. 2 is an enlarged sectional view of section A in Fig. 1, and Fig. 3(a) (
b) is a circumferential cross-sectional view of the tire explaining the influence of the reinforcing ply on the belt layer, and Figures 4(a), (b), and (c) are the first
FIG. 2 is a meridian cross-sectional view of a tire used in a test example. 2... Carcass layer 3... Carcass ply 4.
... Code 5 ... Tire equatorial plane 7 ...
Tread 8... Belt layer 8... Belt ply 10... Cord 11... Reinforcement layer
12... Reinforcement ply 13... Cord 14
...First reinforcing ply 15...Second reinforcing ply 1B
, 1? ...Si, Ruda one end 18.18...Outside point
20.21...Inside point W...Tread width Patent applicant Brideston Co., Ltd. Agent Patent attorney Ta 1) Toshio Figure 2 4.10.13...Code Figure 3 Figure 4 Figure 4

Claims (2)

[Claims] (1) a carcass layer consisting of at least one carcass ply in which a cord substantially extending in the radial direction is embedded; a tread disposed on the radially outer side of the carcass layer;
a belt layer consisting of at least two belt plies disposed between the carcass layer and the tread and embedded with cords intersecting at an angle of 10 degrees to 40 degrees with respect to the tire equatorial plane; A flat radial tire with a ratio of 0.85 or less, which has two or fewer layers of reinforcement in which a cord substantially parallel to the tire's equatorial plane is embedded between the belt ply located at the outermost radial direction and the carcass layer. A reinforcing layer consisting of ply is disposed, and at least one reinforcing ply is disposed on both sides of the tire equatorial plane.
It consists of reinforcing plies, and these first and second reinforcing plies extend from the shoulder end of the tire to 1/1/2 of the tread width.
A flat radial tire characterized in that the flat radial tire is located between outer points separated by 7 points and inner points separated by 1/10 of the tread width from the tire equatorial plane. (2) The sum of the elastic modulus in the cord direction per unit width of the reinforcing ply is within the range of 10% to 35% of the sum of the elastic modulus in the cord direction per unit width of the belt ply. Flat radial tire listed.