JPH02114007A - Radial tire for high inner pressure and heavy load - Google Patents

Abstract

PURPOSE:To prevent the occurrence of cracking on the shoulder rib surface, i.e., sipe tear, by extending sipes completed in shoulder ribs at one end on the same side as the extension direction of cords of the outermost layer belt against the extension direction of a tire equator line. CONSTITUTION:A radial tire for a heavy load has a carcass 1 constituted of one or more layers of carcass plies made of cords extended in the radial direction and three belt layers 4-6, for example, arranged on the outside in the radial direction. Ribs 8 and 9 partitioned by four main grooves 7 and extended in the tire peripheral direction are provided on the peripheral face of a tread section 3, and multiple sipes 10 are provided only on the shoulder rib 8 in the tire peripheral direction. The sipes 10 are blind sipes completed in the shoulder rib 8 at both ends, and the sipes 10 are extended in the same direction as the extension direction of cords 11 of the outermost belt layer 4 against the extension direction of a tire equator line X over the whole length.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a high internal pressure heavy load radial tire that is used with an internal pressure as high as 9 to 12 kg/cm, and is particularly applicable to new transportation systems. This effectively prevents the occurrence of so-called cyptair when applied to a vehicle.

(Prior art) An example of a conventional tire of this kind used in subways is the one shown in Figure 3, in which the upper half shows a part of the tread pattern, and the lower half shows a part of the tread pattern in the width direction of the tire. A portion of each cross section is shown.

In the lower half of the figure, 51 indicates a carcass made of one or more carcass plies, and 52 indicates a belt located on the outer layer side of the carcass 51.

Here, the belt 52 has three belt layers 53.54°5
The cords, for example steel cords, of each belt layer 53, 54, 55 extend in a direction intersecting the tire equator line XX, as partially shown in the upper half of the figure.

Further, 56 in the figure indicates a tread portion, and this tread portion 56
are four circumferential main grooves 5 extending in a zigzag shape in the circumferential direction.
7 and a plurality of sipes 60 provided at substantially equal intervals in the tire circumferential direction on the shoulder rib 58 located in a part of the shoulder of the tire. and has.

Here, each sipe 60 is a so-called blind sipe whose both ends end within the shoulder rib,
The center portion of each sipe 60 in the tire width direction is
It extends toward the same side as the extending direction of the cord 53a of the belt layer 53 located at the outermost layer with respect to the extending direction of the tire equator line XX.

(Problem to be solved by the invention) By the way, in this type of tire, 9 to 1
Due to the high internal pressure of 2 kg / cm2, the siflow is 0.
On the other hand, each cord 53a of the outermost belt layer 53 applies a large force in the tensile direction when the tire is depressed, and when the tire is in contact with the ground. In addition to receiving a force in the compression direction, and again receiving a force in the tensile direction when kicking off,
In this conventional tire, the bent end portions 60a and 60b of each sipe 60 adjacent to both ends of the central portion are as follows.
With respect to the extending direction of the tire equator line XX, the outermost layer belt 7
1! The direction opposite to the extending direction of the cord 53a of f53 (
Therefore, in particular, the direction in which the outer end of the sipe 60 in the tire width direction, which is the part that undergoes the largest amount of deformation, further widens its cut width each time a tensile force is applied to the cord 53a Therefore, there is a problem that cracks occur on the shoulder rib surface due to stress concentration from the outer edge position of the sipe 60 in the tire width direction, that is, so-called sipe tear. Ta.

Here, when the above-mentioned sipes 60 are opened at the side end surfaces of the tread portion 56, another type of sipe tear occurs from the open end of the sipes 60 and the sipe bottom in the vicinity thereof toward the sidewall. There was a problem.

The present invention advantageously solves the problems of the prior art, and provides a high internal pressure, heavy load radial tire that can extremely effectively prevent the occurrence of cyptair.

(Means for Solving the Problems) This invention provides a carcass formed of one or more layers of carcass plies consisting of cords substantially extending in the radial direction, and cords arranged on the outside of the carcass in the radial direction and intersecting the tire equator line. a belt formed of a plurality of belt layers made of cords facing in the direction of the tire, a tread portion, and a plurality of sipes provided at the shoulders of the tread portion at intervals in the tire circumferential direction; In a radial tire for heavy loads with high internal pressure and a boat-like internal structure, at least the portion of each sipe, at least one end of which ends within the shoulder, is located outward in the tire width direction from the side edge of the outermost belt layer. The end portion extends in the same direction as the cord of the outermost belt layer with respect to the tire equator.

(Function) In this radial tire, at least the end portion of the sipe, which is located outside the side edge of the outermost belt layer in the tire width direction, is aligned in the direction in which the tire equator line extends. On the other hand, when the belt cord is oriented in the same direction as the extending direction of the cord in the outermost belt layer, when the belt cord receives a force in the tensile direction, the sipe end portion is deformed in a direction that reduces the cutting width. As a result, concentration of stress on the sipe edge is effectively prevented, and the occurrence of sipe tears from the sipe edge can be sufficiently prevented.
This is substantially the same whether or not the outer edge of the sipe is open to the side end surface of the tread portion.

Note that the direction of the sipe end portion facing the same direction as the extending direction of the cords of the outermost belt layer with respect to the extending direction of the tire equator line means that the sipe end portion is oriented toward the tire equator line. In fact, the sipe end portion should be oriented in any direction between them, including both the direction at zero degrees with respect to the tire meridian and the direction at zero degrees with respect to the tire meridian.
Even when extending at an angle of 0 degrees to the tire equator line, even when extending at an angle of 0 degrees to the tire meridian, the direction of the end portion of the sipe must be aligned with the tire equator line. The generation of cyptair can be effectively prevented compared to the conventional technology in which the direction is opposite to the extending direction of the cyptair.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a diagram showing an embodiment of the present invention. In the figure, 1 indicates a carcass, 2 indicates a belt disposed on the outside of the carcass 1 in the radial direction, and 3 indicates a tread portion forming a tread surface. show.

Here, the carcass 1 is formed of one or more carcass plies consisting of cords substantially extending in the radial direction,
The belt 2 is a plurality of belt layers consisting of cords oriented in a direction intersecting the tire equator line XX, here a three-layer belt Ji! Formed at i4, 5.6.

Further, the tread portion 3 is provided with five ribs 8 and 9 which are partitioned by the four circumferential main grooves 7 and extend in the tire circumferential direction, and among these ribs, at least the shoulder rib 8 In the illustrated example, only the shoulder rib 8 is provided with a plurality of sipes 1o located at substantially equal intervals in the tire circumferential direction.

Here, as shown in the upper half of the figure, each of these sipes 10 is a blind sipe whose ends end within the shoulder rib, and each of these sipes 10 is defined as a blind sipe that ends within the shoulder rib. , belt J located at the outermost layer with respect to the extending direction of the tire equator line x-x! It is made to extend toward the same side as the extending direction of the cord 11 of ii4. According to this, the outer end of each sipe 10 in the tire width direction, which is the part with the largest amount of deformation, in other words, is located on the outer side in the tire width direction than the side edge of the belt layer 4 located at the outermost layer. The end portion of the belt layer 4 will also face the same side as the cord 11 of the belt layer 4.

Here, the orientation of the sipes 10 on the same side as the extending direction of the cords 11 of the outermost belt layer 4 with respect to the extending direction of the tire equator line XX means that an appropriate position on the sipes, Tire equator line X-
When a rectangular coordinate system is formed by a line segment parallel to It is also possible to align the direction with one coordinate axis.

In this example, it is also possible to open either end of each sipe 10 alternately or uniformly in the groove wall or tread side end surface of the circumferential main groove 7.

According to the tire in which the orientation of the sipes 10 is selected in this way, even if a large force in the tensile direction is applied to the cord 11 of the outermost belt N4 when stepping in and kicking out during load transfer of the tire, the tensile force is , especially sipe l
The occurrence of cracks on the shoulder rib surface from the outer edge of the sipe is effective because it causes deformation in the direction of reducing the cut width at the outer edge in the tire width direction, which is the part with the largest amount of deformation. This is effective when the extending direction of the sipes 10 is made to coincide with the extending direction of the cord 11 in the above-mentioned orthogonal coordinate system.

This deformation behavior of the outer end of the sipe is almost the same even when one end of the sipe 10 is opened at the side end surface of the tread portion 3, and the force in the tensile direction acting on the cord 11 is
This not only does not widen the cut width of the sipe lO, but rather causes deformation in the direction of reducing the cut width, which effectively prevents the occurrence of cracks on the side end surfaces of the tread portion. .

Thus, according to this tire, it is possible to effectively prevent sipe tears occurring from the edge of the portion of the sipe 10 that undergoes the greatest amount of deformation.

FIG. 2 is a diagram showing another embodiment of the present invention, and this example shows a plurality of sipes 12 formed on the shoulder rib 8.
In each of the above, only the end portion of each sipe 12 located outside in the tire width direction from the side edge of the belt layer 4 located at the outermost layer is as shown in the orthogonal coordinate system in the figure.
It is oriented toward the same side as the extending direction of the cords 10 of the outermost belt layer 4 with respect to the extending direction of the tire equator line XX.

According to this example, the portion of the sipe 10 that undergoes the greatest amount of deformation, in other words, the portion that is likely to become the proximal end of the sipe tear, faces the same side as the extending direction of the cord 10.
When a tensile force is applied to the cord 10, the sipe end portion also deforms in a direction that reduces the sipe cut width, as in the previous example, and as a result, the sipe tear from the sipe edge - will be effectively prevented from occurring. Note that this is substantially the same when the sipe end opens at the tread portion side end surface.

In addition, as in this example, when the sipe 12 is bent significantly, the bent portion should be formed as a curved portion with the largest possible radius of curvature in order to prevent the occurrence of sipe tear from the bending point. is preferred.

Therefore, this embodiment can also sufficiently prevent the occurrence of cyptairs.

[Comparative example]

Below, a comparative test regarding the occurrence of cyptair will be described for the invention tire shown in FIG. 1.2 and the conventional tire shown in FIG. 3.

・Test tire TBT? E 13.50/85 R16/Tire specifications Innermost belt layer width for both the invention tire and conventional tire: 190 am Cord, cross angle developed view with respect to the equator line, rising right 70" Intermediate belt layer width: 210 mm Cord, equator line 20' upward to the right in a developed view of the intersecting angle to the cord's equator line Width of the outermost belt layer 185 mm 20' upward to the left in a developed view of the intersecting angle of the cord to the equator line Tread width 216 mm Circumferential main groove Depth 8 mm Maximum width 18 mra Minimum width 12 mm Circumference Distance between the groove bottom of the main groove and the belt (mm) Supply internal pressure 11.7 kg/crl+” Invention tire I A tire having the tread pattern shown in Fig. 1 (the extending direction of the outer end of the sipe is the tire equator) 70° with respect to the tire equator direction) ・Invented tire ■ A tire with the tread pattern shown in Figure 2 (extending direction of the outer end of the sipe is 50° with respect to the tire equator direction) ・Conventional tire As shown in Figure 3 (The extending direction of the outer end of the sipe is 130' with respect to the tire equator direction.) ・These tires are installed on the drive car of a subway car and 10
The occurrence of cyptair was visually inspected after the vehicle had been driven for 0.000 km, and the results were as shown in the following table.

According to this table, all invented tires are
It is clear that the occurrence of this can be significantly reduced compared to conventional tires.

(Effects of the Invention) As is clear from the above description, according to the present invention, in particular, the extending direction of at least the portion of the sipe with the largest amount of deformation is set relative to the extending direction of the tire equator line. ,
By orienting the cord in the same direction as the extending direction of the cord of the outermost belt layer, it is possible to significantly reduce the occurrence of cyptair.

[Brief explanation of the drawing]

Figures 1 and 2 are diagrams showing an embodiment of the present invention, and Figure 3 is a diagram showing a conventional example. l...Carcass 2...Belt 3...
Tread portion 7...Circumferential main groove 8.9...Rip 10, 12...Sipe 4.5.6...Belt layer...Shoulder rib) 11...Code

Claims (1)

[Claims] 1. A carcass consisting of one or more carcass plies, a belt consisting of a plurality of belt layers with cords of each belt layer extending in a direction intersecting the tire equator line, and a tread portion. , a radial tire for high internal pressure and heavy loads comprising a plurality of sipes provided at the shoulder of the tread portion at intervals in the tire circumferential direction, at least the outermost layer of each sipe having at least one end ending within the shoulder; The end portion of the portion located outside in the tire width direction from the side edge of the belt layer located at An elongated radial tire for high internal pressure and heavy loads.