JPH02283504A - Radial tire for high internal pressure heavy load - Google Patents

Abstract

PURPOSE:To prevent partial wear in a radial tire for subways or the like by making hollow the innermost layer of belt layers, making the width of intermediate layer the maximum and specifying the relation of respective layers widths, specifying rubber characteristics of a part between the bel and bolt layers, and forming narrow grooves of specified widths and depths. CONSTITUTION:An innermost layer 12c of a belt layer 12 of three layer structure has a hollow part at the central part in the tire width direction, the width W1 of an intermediate belt layer 12b is made 80-10% of the tread width W, and the widths W2 of innermost, outermost layers and the hollow part width W3 are set to be 80-98% and 15-50% respectively with respect to the width W1 of the intermediate layer 12b. The pulling modulus in 100% rubber between respective bolt layers 12a-12c and belt layer is set to be 50-90kg/cm<2>. At a circumferential rib 18, there is formed narrow grooves 20 with groove width of 2mm or less and grove depth of 30-110% of the grove depth (5-30mm) of the circumferential main groove 16. With the structure partial wear is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Prior Art) The present invention relates to a high internal pressure heavy load radial tire that is used with a filling internal pressure as high as 9 to 12 kg/cr. It is applied to the running wheels of new transportation system vehicles and extremely effectively prevents the progression of uneven wear.

(Prior Art) As a conventional tire of this type, for example, there is one shown in FIG. Some of them are shown.

In the lower half of the figure, reference numeral 51 indicates a carcass consisting of one or more layers of carcass ply, and a belt indicated by reference numeral 52 is disposed on the outer layer side of the crown portion.

Here, the belt 52 consists of three belt layers 53, 54 and 55, and the cord of each belt layer, for example, a steel cord, is connected to the tire equatorial plane x- Extends in the direction intersecting X.

Further, in the figure, reference numeral 56 indicates a tread portion, and this tread portion 56 has five circumferential main grooves 57 defined by four circumferential main grooves 57 that substantially extend in a zigzag shape in the circumferential direction. It has ribs 59.

(Problem to be Solved by the Invention) By the way, in such a conventional tire, the tread portion 5
6 to sufficiently increase the rigidity of the belt to improve wear resistance and traction performance [under the objective, three steel belt layers 5
3.54 and 55 are buried seamlessly from one side edge to the other side edge in the tire width direction, so based on the action of the guide wheel that contacts the track side wall, guide plate, etc. When steering the vehicle, an unnecessarily large cornering force is generated, and the tire tread surface 58 receives a large input from the road surface.
Uneven wear due to dragging occurs on the tire tread surface 58.

That is, the circumferential rib 5 that extends in the tire width direction faces the circumferential main groove 57 that extends in a zigzag shape in the circumferential direction of the tire.
Uneven wear occurs on the protruding corner portion 60 of No. 7, particularly on the tip 60a thereof, and the uneven wear progresses along the edge 61 of the rib 59 in a manner that gradually expands in the circumferential direction and width direction of the tire.

In general, the shoulder sagging of the edge 6t of the circumferential main groove due to this uneven wear, which is called railway wear or river wear, not only makes the tire look unsightly, but also makes the circumferential main groove 57
This adversely affects tire performance, particularly traction control performance and braking performance, which depends on the function of the tire, and also significantly reduces the life of the tire.

This invention solves the problems of the prior art, and effectively suppresses the occurrence of uneven wear by sufficiently reducing the cornering force, and also solves the problem of circumferential ribs, which cannot completely avoid the occurrence of uneven wear. It is an object of the present invention to provide a radial tire for heavy loads with high internal pressure that can extremely effectively prevent edge wear from progressing in the width direction of the tire.

(Means for Achieving the Object) This invention provides a belt comprising a carcass made of one or more carcass plies and three belt layers, with the hood of each belt layer extending in a direction intersecting the tire equatorial plane. and,
A tread portion forming a tire tread surface, and a circumferential main groove extending substantially in a zigzag shape along the circumferential direction of the tire and forming a plurality of continuous or discontinuous zigzag circumferential ribs. In the radial tire comprising: (a) the innermost belt layer has a hollow structure with the center portion removed in the tire width direction, and (b) the width of the intermediate belt layer is set to the width of each of the innermost layer and the outermost layer. The width of the belt layer is 80% to 110% of the tread width, and the width of each of the innermost and outermost belt layers is 80% of the width of the middle belt layer.
98% of the width of the innermost belt layer, and the hollow width of the innermost belt layer is 15 to 50% of the width of the intermediate belt layer; (c) each belt layer and each The 100% tensile modulus of the rubber located between the belt layers is 50 to 90 kg/cm'', and (d) narrow grooves are formed in the circumferential ribs within a range of 5 to 25% of the width of the circumferential ribs from the edge. The groove width of the narrow groove is 2M or less, and the groove depth is 30% to 110% of the circumferential main groove having a groove depth of 5 to 30m+11.

Here, the narrow grooves can be provided only in the circumferential protruding corners defining the circumferential ribs extending in a zigzag shape.

(Function) This high internal pressure, heavy-duty, small-duty radial tire is designed to suppress the growth of the tire diameter.By making the innermost belt layer have a hollow structure, the original function of the belt layer can be fully demonstrated. Furthermore, since the cornering force of the tire can be advantageously reduced without reducing the rigidity of the tread side edge portion or the durability of the belt, uneven wear caused by the tire tread receiving large input from the road surface can be reduced. can be effectively suppressed.

Here, if the belt layers other than the innermost belt layer have a hollow structure, it becomes impossible to obtain a uniform round shape when filling the tire with internal pressure.

Moreover, in this tire, the narrow groove formed within 5 to 25% of the width of the rib from the edge of the circumferential rib protrudes in the tire width direction of the circumferential rib that extends in a zigzag shape in the tire circumferential direction. This reduces the burden of cornering force input acting on the tip of the protruding corner, and also effectively prevents the progress of edge wear in the tire width direction, resulting in a uniform wear pattern.

Here, the width of the intermediate belt layer is made wider than the width of the other belt layers, and the width is within the range of 80 to 110% of the tread width.The reason why the width of the intermediate belt layer is made wider than the width of the other belt layers and within the range of 80 to 110% of the tread width is because the side edges of the tread part are sufficiently reinforced. This is to advantageously improve the abrasion resistance of the side edge portions of the belt layer, while effectively suppressing the diameter growth at the edge portions of the belt layer of the intermediate layer. The width of the layer is 80 to 9 of the width of the middle belt layer.
The reason why the width is within the range of 8% is that if the width is less than 80%, the rigidity of the side end portion of the tread portion and the belt durability cannot be sufficiently increased, whereas if it exceeds 98%, the belt layer This is because cracks occur from the edges more quickly and the growth rate of the cracks becomes faster.

The reason for setting the hollow width of the innermost belt layer to be within 15 to 50% of the width of the intermediate belt layer is that if it is less than 15%, cornering force can be effectively reduced. If it exceeds 50%, the rigidity of the tread portion at both ends in the tire width direction becomes too low.

Furthermore, the reason why the 100% modulus of each belt layer and the rubber located between the belt layers is set to 50 to 90 kg/cm'' is that during load transfer of an inflated tire, the rubber between the belt layers in the tire width direction and the circumferential direction This is to advantageously reduce the shear strain of the belt layer and partially reduce the sticking of the rubber by the side edges of the belt layer, making it possible to greatly delay the occurrence of cracks in the rubber caused by pecking. It is from.

Here, if the 100% tensile modulus is less than 50 kg/c, the shear strain will be large (while it becomes too much, if the 100% tensile modulus is less than 50 kg/c
/c+s'', the rubber rigidity becomes too high and peeling is likely to occur between the dam and the rubber constituting other parts.

Furthermore, the narrow grooves of the circumferential ribs should be formed within a range of 5 to 25% of the width of the rib from the edge of the circumferential rib.If the width is less than 5%, the narrow grooves of the circumferential ribs should be formed in the rib portion located inside the narrow grooves. It is not possible to reduce side force manpower, and
This is because the thickness of the rib portion sandwiched between the circumferential main groove and the narrow groove that define the rib is not sufficient, so there is a risk that the thin portion may be chipped during running.

On the other hand, the formation position of the narrow groove is 25% from the edge of the circumferential rib.
If it is located inside the rib beyond the narrow groove, as in the case described above, it is not possible to reduce the side force input to the rib portion located inside the narrow groove, and if the rib is This is because edge wear is likely to occur in the rib portion sandwiched between the circumferential main groove and the thin groove.

The width of the narrow groove is 2 m or less, preferably 1.5 m.
m, and the groove depth is 30 to 110% of the circumferential main groove, which has a groove depth of 5 to 30IIII and defines the circumferential rib.

This is because when the groove width of the narrow groove becomes larger than 2 m, the movement of the part between the narrow groove and the edge of the circumferential rib increases.
This is because river wear is likely to occur, and the groove walls of narrow grooves with a groove depth of 2 mm or less can dissipate side force input by contacting each other during load transfer of the tire. This is because river wear is prevented from occurring from the edge portions of the ribs, particularly from the protruding corner portions of the ribs.

Further, the groove depth of the narrow groove can be set to a depth within the range of, for example, 5 to 301111. The groove depth of the circumferential main groove is 30
Depth within the range of ~110%, preferably groove depth of 5~
By making it comparable to that of the circumferential main groove of 30■,
It is possible to sufficiently prevent the edge wear of the circumferential ribs from progressing in the tire width direction, and also to sufficiently prevent the occurrence of cracks from the bottom of the narrow grooves.

Since river wear is first generated at the protruding corners of the circumferential ribs extending in the circumferential direction of the tire in a zigzag pattern, the narrow grooves may be provided at least at the protruding corners.

(Example) Preferred embodiments of the present invention will be described in detail below.

FIG. 1 is a diagram showing an embodiment of the present invention, where 0 indicates a carcass, 12 indicates a belt disposed outside the crown of the carcass, and 14 indicates a tread portion forming a tire tread surface. show.

The carcass IO consists of one or more carcass plies consisting of cords extending substantially in the radial direction of the tire;
The belt 12 is oriented in a direction intersecting the tire equatorial plane xx (a belt layer 12a made of cords).

It is formed from three pieces, 12h and 12c.

Of these belt layers +2a, 12b and 12c,
The belt layer 12c close to the axis of rotation of the tire is the innermost belt layer, the belt layer 12a spaced apart from the axis is the outermost belt layer, and the belt layer sandwiched between these belt layers is an intermediate belt layer. Here, the innermost belt layer t
2c 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 belt layer 12b is larger than that of the other belt layers 12.
It is larger than that of a and 12c, and the tread width W is 80~
By setting the width within the range of t'tc+%, the rigidity of the side end portions of the tread portion 14 is increased, and the diameter growth of the end portion of the intermediate belt layer 12b is effectively suppressed, thereby sufficiently preventing peeling there. to prevent.

Furthermore, the innermost and outermost belt layers 12a and 12c
The width W of each of the intermediate belt layers 12b is
By setting the width within the range of 80 to 98% of I, the rigidity of the side edges of the tread portion and the durability of the belt are sufficiently increased, while the occurrence of cracks from the edges of these belt layers 12a and 12c is delayed. and slow down its growth.

By setting the hollow width W3 of the innermost belt layer 12c within a range of 15 to 50% of the width Wl of the intermediate belt layer 12b, the rigidity of both end portions of the tread portion i4 in the tire width direction is low. On the other hand, the cornering force can be effectively reduced.

In this embodiment, the intersecting angles of the cords of each belt layer with respect to the tire equatorial plane For the belt layer 12b, the code may be set upward to the right, from 10° to 30', and for the outermost belt layer 12a, the code may be set to a value within the range 106 to 30', upward to the left. can. Of course, contrary to the illustrated example, the cords of the innermost and intermediate belt layers may extend upward to the left, and the cords of the outermost belt layer may extend upward to the right.

Furthermore, the rubber coating each cord of the belt layers 12a, 12b and 12c and the rubber provided between the belt layers have a 100% tensile modulus of 5.
0 to 90 kg/cm" is preferable, and by using such a rubber, the shear strain of the rubber between the belt layers can be made as small as 1 min. On the other hand, the belt 12 On the other hand, the tread rubber disposed radially outward of the tire to form the tread portion 14 is preferably a rubber blended with 15% or more of NR in order to prevent deterioration of cut resistance and chipping performance.

In this embodiment, the tread portion 14 made of the blended rubber has four circumferential main grooves 1 having a zigzag shape and extending substantially in the circumferential direction of the tire and having a groove depth of 5 to 30 mm.
6 defines five circumferential ribs 18 extending in the circumferential direction of the tire, and is further spaced R2 apart from each edge of the circumferential rib 18, that is, from the edge of the circumferential rib. By forming the narrow groove 20 in the inner part of the rib within a range of 5 to 25% of the width R8 of the rib, the circumferential rib 18
It is possible to reduce the cornering force input acting on the edge portion, and to effectively prevent the occurrence of edge wear at the edge portion.

In addition, in this embodiment, these narrow grooves 20 are extended in a zigzag shape along the circumferential main groove 18 over the entire circumference of the tire, spaced apart from each other in a substantially parallel manner. If it is, the narrow groove 20 may be formed only in the protruding corner portion P of the circumferential rib 18, as shown in FIG.

These narrow grooves 20 have a groove width of 2 mm or less and a groove depth of
By setting the depth within the range of 30 to 110% of the groove depth of the circumferential main groove 16, undesirable movement of the upright wall 22 formed between the narrow groove 20 and the edge portion of the circumferential rib 18 is prevented. In addition, the cornering force is dispersed as the groove walls facing each other in the narrow grooves 20 may come into contact with each other during load transfer of the tire, and the occurrence of river wear at the edge portion of the circumferential rib is effectively prevented. It is possible to prevent the edge wear of the circumferential ribs from progressing in the width direction of the tire, and also to prevent the occurrence of cracks from the bottom of the narrow grooves.

FIG. 3 is a diagram showing still another embodiment of the present invention, in which the tread portion 14 has a groove width within a range of 15III in the tire width direction from the side edge of the outermost belt layer 12a. 2 mm or less, and the groove depth extends in the tire circumferential direction within a range of 50 to 110% of the circumferential main groove 16 having a groove depth of 5 to 301 IIB.

By forming such narrow grooves 24 in the side end portions of the tread portion 14, edge wear at the side end portions caused by dragging of the tire tread is suppressed, and the wear is directed to the center portion in the width direction of the tire. This is because it is possible to suppress the progress of the narrow grooves 24. Specifically, when the other narrow grooves 24 are located more than 15 m outward in the tire width direction, the inner side of the narrow grooves 24 in the tire width direction The cornering force input to the edge of the rib located at This is because the range of wear becomes wider.

Although the present invention has been described below based on illustrated examples, it is not limited to these examples, and various modifications can be made within the scope of the claims.

1 Comparative Example 1 A comparative test regarding the occurrence of uneven wear between the tire of the present invention and the comparative tire will be described below.

◎Test tire/specification size is [13,50/80R16 tire, 9.5
Assemble the rim to the 0VX16 rim and set the filling internal pressure to 9.0kg.
/cm”.

- Invention Tire 1 A tire having a tread pattern shown in Fig. 1, in which the width of the intermediate belt layer is 95% of the tread width,
Set the intersection angle of the innermost layer belt cord to the tire equatorial plane to the right■
The intersecting angle of the middle layer belt cord with the tire equatorial plane is 1 - 20 degrees to the right, and the intersection angle of the outermost layer belt cord with the tire equatorial plane is - [ - 20 degrees to the left. The drawing width is 30% of the width of the intermediate belt layer, and the 100% tensile modulus of these belt layers and the rubber located between the belt layers is 70 kg/c+
Further, a thin groove is formed in the circumferential rib at a position 9% of the width of the rib from the edge, and the width of the narrow groove is 1 mm, and the groove depth is 10ffl111. The direction is 100% of the main groove.

- Invention Tire 2 A tire having a tread pattern shown in FIG. 2, the structure of which is similar to the tire shown in Invention 1.

・Comparison tires One having a tread pattern shown in FIG.

◎Test method Each tire was mounted on the drive shaft of a subway car, and lO
The occurrence of uneven wear, particularly bar wear wear, after 11,000 km of driving was inspected using 11 sights, and was converted into an index. Note that the smaller the index, the better the uneven wear resistance.

◎Test Results Table According to this table, the tire of the present invention has a hollow structure in the innermost belt layer, and at least the protruding corner portion of the rib defined by the zigzag-shaped circumferential main groove extending in the tire circumferential direction. It has been found that by providing narrow grooves near the edges of the ribs, it is possible to very effectively prevent uneven wear, particularly river wear, from occurring near the edges of the ribs, as well as its progression.

(Effects of the Invention) Thus, according to the present invention, it is possible to suppress the occurrence of uneven wear that occurs along the edge of the rib defined by the circumferential main groove extending in a zigzag shape in the tire circumferential direction, and to reduce uneven wear. It is possible to sufficiently prevent the growth of the tire in the circumferential direction and the width direction of the tire, and the wear life of the tire can be greatly extended.

[Brief explanation of drawings]

FIG. 1 is a diagram showing one embodiment of a tire according to the present invention, FIG. 2 is a diagram showing a tread pattern of yet another embodiment of the present invention, and FIG. 3 is a diagram showing a further embodiment of a tire according to the present invention. Figures showing another embodiment and Figure 4 are diagrams showing a conventional tire. lO...Carcass 12...Belt 14...
・Tread part 16... Circumferential main groove 18... Circumferential rib 2G, 24... Thin groove 22... Standing wall Fig. 2 Fig. 4

Claims (1)

[Claims] 1. A carcass consisting of one or more layers of carcass ply, a belt consisting of three belt layers with cords of each belt layer extending in a direction intersecting the tire equatorial plane, and a tire tread. A radial tire comprising: a tread portion; and a circumferential main groove that extends in the tread portion substantially in a zigzag shape along the circumferential direction of the tire and forms a plurality of continuous or discontinuous zigzag circumferential ribs. (a) The innermost belt layer has a hollow structure in which the center portion is removed in the tire width direction, and (b) the width of the intermediate belt layer is wider than each of the innermost and outermost belt layers. As, the tread width is 80~
110%, and the width of each of the innermost and outermost belt layers is within the range of 80 to 98% of the width of the intermediate belt layer, and the hollow width of the innermost belt layer is
The width is within the range of 15 to 50% of the width of the intermediate belt layer, and (c) the 100% tensile modulus of each belt layer and the rubber located between each belt layer is 50 to 90 kg/c.
m^2, (d) forming a narrow groove in each circumferential rib located within a range of 5 to 25% of the width of the circumferential rib from the edge thereof,
The groove width of the narrow groove is 2 mm or less, and the groove depth is 5 to 30 mm.
A radial tire for heavy loads with high internal pressure, characterized in that the groove depth is 30 to 110% of the circumferential main groove. 2. The radial tire for high internal pressure and heavy loads according to claim 1, wherein the thin grooves are provided at the protruding corners of the circumferential ribs extending in a zigzag shape.