JPH02158402A - High internal pressure heavy loading radial-ply tire - Google Patents

Abstract

PURPOSE:To improve the extent of abrasive resistance as well as to abate a sipe tear by forming an innermost layer among three steel belt layers into a hollow structure, and setting width of the three layers and width of the hollow part to a specified relationship, while extending an outer end of a sipe in the same side as the extending direction of a cord at the outermost layer. CONSTITUTION:An innermost layer steel belt layer 6 is formed into a hollow structure removing a central part in the tire width direction. In addition, width W1 of an intermediate layer steel belt layer 5 is made larger than each width W2 of other steel belt layers 4, 6, setting it to 80 - 110% of tread width W. Each width W2 of these innermost and outermost steel belt layers 4, 6 is set to 80 - 98% to the width W1 of the intermediate layer steel belt layer 5. Then, hollow width W3 of the innermost layer steel belt layer 6 is set to 15 - 50% with the width W1 of the intermediate layer steel belt layer 5. On the other hand, an outer end in the tire width direction of each sipe 10 is extended at the same side in the extending direction of a cord in the outermost layer steel belt layer 4.

Description

Detailed Description of the Invention (Industrial Application Field) This invention relates to a radial tire for heavy loads with high internal pressure, which is used with an internal pressure as high as 9 to 12 kg/cm. It is applied to mole rails, vehicles for new transportation systems, etc., to improve wear resistance and uneven wear resistance, and to effectively prevent the occurrence of so-called subiteration.

(Prior Art) An example of a conventional tire of this kind used in subway cars is the one shown in Fig. 2, in which the upper half shows part of the tread pattern, and the lower half shows the tire. A part of the cross section in the width direction is shown.

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

Here, the heald 52 includes three steel heald layers 53,
54.55, each steel belt layer 53.5/1
55 code, as shown in part in the upper half of the figure,
It extends in a direction intersecting the tire equatorial plane XX.

Further, numeral 56 in the figure indicates a tread portion, and this tread portion 5
6 has five ribs 5859 partitioned by four circumferential main grooves 57 extending in a zigzag shape in the circumferential direction, and a shoulder rib 58 located at a part of the shoulder of the tire. It has a plurality of sipes 60 that are provided at substantially equal intervals in the direction and function to improve uneven wear resistance and abrasion resistance.

Here, each sipe 6o 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 extends toward the same side as the extending direction of the cord 53a of the steel heald layer 53 located at the outermost layer with respect to the tire equatorial plane X-x.

(Problems to be Solved by the Invention) However, in such conventional tires, it is necessary to sufficiently increase the rigidity of the red portion 56 to improve wear resistance and traction performance. Since each of the three steel bell layers 53, 54, 55 is buried seamlessly from one side edge to the other side edge in the tire width direction, track side walls, guide plates, etc. When steering a vehicle based on the action of a guide wheel in contact with the wheel, conventional tires that perform load transfer generate unnecessary large cornering forces, causing the tire tread to receive large inputs from the road surface. , because the tire is
There is a problem in that uneven wear and early wear are likely to occur due to the dragging.

In addition, this type of tire is originally 9 to 12k
In addition to the fact that the sipe 60 tends to widen its cut width due to the action of internal pressure as high as g/cm2, each cord 53a of the outermost steel heald layer 53 is depressed when the tire load is transferred. At times, the center of each sipe 60 is subjected to a large force in the tensile direction, a force in the compressive direction during contact with the ground, and a force in the tensile direction again when kicking off. In particular, when the bent end portions 60a and 60b adjacent to both ends of the portion face toward the opposite side to the extending direction of the cord 53a of the outermost steel heald layer 53 with respect to the tire equatorial plane XX, the sipe 60 is the part with the largest amount of deformation,
Each time a tensile force is applied to the cord 53a, the outer end in the tire width direction is deformed in a direction that further widens the cut width. There has been a problem in that cracks, so-called cyptears, occur on the shoulder rib surface due to stress concentration from the edge position.

Here, when the above-mentioned sipes 60 are opened on the side end surface of the tread portion 56, another type of sipe tear is generated from the sipe bottom at the open end of the sipes 60, which points in the direction of the sipe A-ru. There was a problem.

The present invention advantageously solves the problems of the prior art, and provides a radial tire for heavy loads with high internal pressure that exhibits poor wear resistance and uneven wear resistance, and can extremely effectively prevent the occurrence of cyptear. It provides:

(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 of the tire, and a carcass that is disposed on the outside of the carcass in the radial direction, A heald formed of three steel cord layers consisting of cords facing in a direction intersecting the surface, a tread portion forming the tire tread surface, and a plurality of healds provided at intervals in the tire circumferential direction on the shoulders of this tread portion. In this radial tire for heavy loads with high internal pressure and a boat-like internal structure, the innermost steel belt layer has a hollow structure by removing the center part in the width direction of the tire, and the steel belt in the middle layer The layer is wider than each of the innermost and outermost steel belt layers, and the width is 80% to 110% of the tread width.
In addition, the width of each of the innermost and outermost steel belt layers is 80 to 90% the width of the middle steel heald layer.
The width should be within the range of 8%, and the hollow width of the innermost steel heald layer should be 15% of the width of the middle steel heald layer.
~50%, and at least the outer end portion of the sipe on the shoulder in the tire width direction, in particular, the outermost portion in the tire width direction from the side edge of the outermost steel belt layer, at the tire equator. With respect to the surface, the cord extends in the same direction as the cord of the outermost steel belt layer.

Note that the direction of the sipe end portion facing the same direction as the cord extension of the outermost steel belt layer with respect to the tire equator plane means that the sipe end portion faces in the direction of the tire equator line. This means that the cord extends within the same quadrant as the direction in which the cord extends, including both the direction that is zero degrees with respect to the tire meridian and the direction that is zero degrees with respect to the tire meridian. Even if the sipe end portion extends at an angle of 0 degrees to the tire equator line or at an angle of 0 degrees to the tire meridian, the orientation of the sipe end portion The occurrence of cyptair can be effectively prevented compared to the conventional technology in which the tire is oriented in the opposite direction to the tire's equatorial plane.

(Function) In this radial tire, the innermost steel belt layer has a hollow structure to advantageously reduce cornering force without reducing the rigidity of the tread side edge portions or the durability of the belt. Therefore, it is possible to sufficiently prevent uneven wear and early wear of the tire caused by the tire tread receiving a large input from the road surface. Here, if the belt layers other than the innermost steel heald layer have a hollow structure, it becomes substantially impossible to obtain a uniform round shape when filling the tire with internal pressure.

Here, the width of the intermediate steel belt layer is made wider than that of the other steel belt layers, and the width is within the range of 80 to 110% of the tread width, which is sufficient to extend to the side end portions of the tread portion. This is to advantageously improve the abrasion resistance of the side end portions, while effectively preventing the ends of the intermediate steel belt layer from peeling off from the rubber. The width of each outer steel belt layer is 80 to 98 times the width of the middle steel belt layer.
If they are less than 80%, the width is within the range of %.
If the rigidity of the tread side end portions and the belt durability cannot be sufficiently increased, and conversely exceeds 98%,
The occurrence of cracks from the edge of the belt layer is accelerated, and
This is because the fissures grow faster.

Furthermore, the reason why the hollow width of the innermost steel belt layer is set within the range of 15 to 50% of the width of the middle steel belt layer is that if it is less than 15%, the cornering force cannot be effectively reduced. Unable to realize, super 50%
This is because the rigidity of the tread portion at both end portions in the tire width direction becomes too low.

Moreover, in this tire, at least the outer end portion of the sipe on the shoulder in the tire width direction extends toward the same side of the tire equatorial plane as the cord extending direction of the steel belt layer located at the outermost layer. As a result, the belt cord is subjected to a force in the tensile direction, and the sipe end portion is subjected to a component force in the direction in which the belt cord extends, and in turn, is deformed in a direction that reduces the cutting width. Since the concentration of stress on the sipe edge in the tearing direction is effectively alleviated, the occurrence of sipe tears from the sipe edge can be sufficiently prevented, which means that the outer edge of the sipe is It is almost the same whether or not the side end face of the part is opened.

(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 which 1 indicates a carcass, 2 indicates a belt disposed on the radially outer side of the carcass L, and 3 indicates a trend forming an ear tread surface. Show part.

Here, the carcass 1 is formed of one or more layers of carcass ply consisting of cords extending substantially in the radial direction of the tire, and the belt 2 is formed of one or more layers of carcass plies consisting of cords extending substantially in the radial direction of the tire. Three belt layers 4,5
．． Formed in step 6.

Among these steel belt layers 4, 5.6, the innermost steel heald layer 6 has a hollow structure in which the center portion in the width direction of the tire is removed for the purpose of reducing the cornering force of the tire. , the width W1 of the intermediate steel belt layer 5 is made larger than that of the other steel belt layers 4.6, and by setting the width within a range of 80 to 110% of the tread width W, the tread portion In addition to sufficiently increasing the rigidity of the side end portion of 3, the steel belt layer 5
It sufficiently prevents the ends of the rubber from peeling off, and furthermore, the innermost layer and the outermost layer of each steel shell) I! 4.
The width W 2 of 6 is the width W 1 of the middle steel heald layer 5.
By setting the width within the range of 80 to 98% of Growth rate can be slowed down.

Also, the hollow radius W of the innermost steel belt layer 6
, 15 to 5 of the width W of the intermediate steel heald layer 5
By setting the width within the range of 0%, the width of the tread portion 3 is
To prevent the rigidity of the central portion in the tire width direction from becoming too low, yet to effectively reduce cornering force.

By the way, the intersection angle of the cord of each steel heald layer 4, 56 with respect to the tire equatorial plane XX is, for example,
In the area shown in the figure, the innermost layer heald cord is 45° to 80° upward to the right, the middle layer belt coat is 10° to 30° upward to the right, and the outermost belt cord is 45° to 80° upward to the right.
In addition to being able to have a value in the range of 10° to 30° upward to the left, it is also possible to have the heald cord of the innermost layer and the middle layer upward to the left, and the heald coat of the outermost layer to be downward to the right.

Moreover, here, by forming four circumferential main grooves 7 in the tread portion 3, the depth of which can be within the range of 5 to 30 mm, the grooves extend in the circumferential direction of the tire. The five ribs 8 and 9 are each partitioned, and among these ribs, at least the shoulder rib 81 in the illustrated example, all the ribs 8 and 9 are provided with a plurality of sipes 10 at equal intervals or irregular intervals in the tire circumferential direction. Form at equal pitch.

These sipes 10 are arranged in the circumferential direction of the tire, for example, from 5 to
It can be formed in an equal pinch at a distance within the range of 40 mm, and the cutting width can be set to 1 mm or less, and the depth can be set to a value within the range of 10 to 110% of the main groove depth,
Further, as shown in the illustrated example, it may be an open sipe with both ends opening to the side surfaces of each rib 8, 9, or it may be a sipe with a small number of ends (both ends ending within the shoulder rib).

Furthermore, for each such sipe 10, at least
The outer end portion in the tire width direction, in the illustrated example, the entirety of each sipe 10 is made to extend toward the same side as the extending direction of the cord 11 of the outermost steel heald layer 4 with respect to the tire equatorial plane X-x. .

Here, orienting the sipe 10 in the same direction as the extending direction of the outermost layer belt cord 11 with respect to the tire equatorial plane XX means that the point of view at an appropriate position on the sipe and an appropriate position on the nid is , means that the sipe 10 extends within the same quadrant as the cord 11 when a rectangular coordinate system as shown is formed by a line segment parallel to the tire equatorial plane XX and the tire meridian. In this case, Sipe 1
It is possible to make the extending direction of 0 coincide with the coordinate axes.

By the way, the tire equatorial plane X-
The intersecting angle with respect to X is preferably within the range of 40° to 90°. That is, Sipe 1 with an intersection angle of 90'
0 can most effectively contribute to improving wear resistance, whereas if it is less than 40 degrees, the sipe sidewall will be in constant contact during tire load transfer, and the sipe will not be able to perform its original function. becomes virtually impossible.

According to the radial tire configured in this manner, cornering force that is unnecessary for this type of tire can be effectively reduced without sacrificing the rigidity of the side end portion of the tread portion and the durability of the belt 2. It is possible to greatly improve the wear resistance and uneven wear resistance of tires.

Further, even if a large force in the tensile direction is applied to the outermost layer belt cord 11 during stepping in and kicking out during load transfer of the tire, the aforementioned sipes 10 are deformed in a direction that reduces the cutting width. , the generation of cracks from the sipes 10 on the side end surfaces of the tread portions and the generation of cracks on the shoulder rib surfaces are sufficiently prevented,
This means that in the orthogonal coordinate system mentioned above, the sipe 10
It is particularly effective when the extending direction of the cord 11 is made to match the extending direction of the cord 11.

Although the above explanation was based on the illustrated example, in addition to using the tire as a slick tire, the tread pattern can also be a block pattern, a lug pattern, etc., or a combination of two or more types of patterns. It is.

Further, here, when the outermost belt cord 11 extends upward to the right, each sipe 10 also has at least
It is necessary to extend the outer end portion in the tire width direction upwardly to the right.

[Comparative example]

Below, a comparative test of the invention tire and the conventional tire regarding wear resistance, uneven wear resistance, and occurrence of cyptear will be explained.

◎Test tire/specifications A tire of size E13.50/85 R16 was assembled on a rim of size 9.00V X16,
An internal pressure of 9.8 kg/cm2 was supplied.

・Invention Tire In a tire having the tread pattern shown in Figure 1, the intersection angle of the innermost layer belt cord with the tire equatorial plane is 65 degrees upward to the right, and the intersection angle of the middle layer belt cord with the tire equatorial plane is 20 degrees upward to the right. The intersection angle with the tire equatorial plane is 20 degrees upward to the left, the hollow width of the innermost steel heald layer is 30% of the width of the intermediate steel belt layer, and the intersection angle of the sipe with the tire equatorial plane is 70 degrees upward to the left. In addition, the sipe cut width is 1 mm or less, the sipe depth is 8.2 mm, the sipe interval is 15 mm in the tire circumferential direction, and the circumferential main groove depth is 9.71. - Conventional tire shown in Figure 2 A tire with a tread pattern similar to the invention tire except that the angle of both ends of the sipes with respect to the tire equator plane was set at 70 degrees. ◎Test method Each tire was mounted on the drive shaft of a subway car and run on the track for 10 minutes. After running for 10,000 km, we visually inspected the occurrence of sipe tear, and evaluated the wear resistance by measuring the amount of wear from the remaining amount of the circumferential main groove. Uneven wear resistance was evaluated by measuring the difference in wear amount.

◎Test results The results of the above test are shown in the table below.

Regarding wear resistance and uneven wear resistance, conventional tires are expressed as an index of 100, and a larger index value indicates a better result.

Table According to this table, it is clear that the invented tire is far superior to the conventional tire in all the test items.

(Effects of the Invention) Thus, according to the present invention, it is possible to significantly improve wear resistance and uneven wear resistance compared to conventional tires, and to significantly reduce the occurrence of cyptear. .

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the present invention, and FIG. 2 is a diagram showing a conventional example. 1...Carcass 2...Belt 3...
Tread parts 4, 5.6...Steel belt layer

Claims (1)

[Claims] 1. A carcass consisting of one or more layers of carcass ply; a belt consisting of three steel belt layers, with the cords of each steel belt layer extending in a direction intersecting the tire equatorial plane; In a radial tire for high internal pressure and heavy loads, which includes a tread portion forming the tire tread and a plurality of sipes provided at intervals in the tire circumferential direction on the shoulders of this tread portion, the innermost steel belt layer is The tire has a hollow structure in which the central part in the width direction is removed, and the intermediate steel belt layer is made wider than the innermost and outermost steel belt layers, and its width is 88% of the tread width.
In addition, the width of each of the innermost and outermost steel belt layers is within the range of 80 to 98% of the width of the intermediate steel belt layer, and the width of the innermost steel belt layer is 0 to 110%. The hollow width is within the range of 15 to 50% of the width of the intermediate steel belt layer, and at least the outer end portion of the sipe on the shoulder in the tire width direction is set relative to the tire equatorial plane.
A radial tire for heavy loads with high internal pressure that extends in the same direction as the cord of the outermost steel belt layer.