JP2010089762A - Run flat tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a run flat tire capable of surely preventing the occurrence of a buckling, which is suitable for traveling on an ice road. <P>SOLUTION: A run flat tire 1 includes a side reinforcing layer 40 which is provided from a buttress part 36 containing an outside end in a width direction of a tread part 34 to a sidewall part 38 continuing to the buttress part 36 and which has a crescent-like cross section shape along a tread width direction and tire radial direction, and a composite belt layer 24 including a two belt layers 20a, 20b and at least one additional belt layer 22. The side reinforcing layer 40 increases the thickness toward the sidewall part 38 from the buttress part 36 in a cross section along the tread width direction and tire radial direction. A ratio G1/G2 of the thickness G1 of the side reinforcing layer 40 in the buttress part 36 to the thickness G2 of the side reinforcing layer 40 in the sidewall part 38 is 0.79 or more. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a run flat tire comprising a side reinforcing layer provided from a buttress portion to a sidewall portion and having a crescent cross-sectional shape, and a composite belt layer having a cross belt layer and at least one additional belt layer, In particular, the present invention relates to run flat tires for icy and snowy roads.

  Conventionally, in the case of a run flat tire in which the vehicle can travel a certain distance even when the internal pressure is greatly reduced, such as when punctured, the side wall portion of the tire is provided with a side reinforcing layer having a crescent-shaped cross section along the tread width direction The structure is widely used (for example, Patent Document 1). The side reinforcing layer suppresses the deformation of the sidewall portion even when the internal pressure is greatly reduced, and enables the vehicle to travel a certain distance.

  In recent years, run-flat tires have been put into practical use as tires suitable for traveling on icy and snowy roads, so-called studless tires. In such run-flat tires for icy and snowy roads, a large number of sipes are formed in the tread portion or rubber with high flexibility is used in order to ensure performance on icy and snowy roads. For this reason, generally, in the run-flat tire for icy and snowy roads, the rigidity of the tread portion is lower than that of the summer tire.

If the rigidity of the tread is low, the internal pressure will drop greatly and the side reinforcement layer will receive most of the load, the tread will warp inward in the radial direction of the tire and buckling will occur that reduces the contact with the road surface. There is. Therefore, buckling is prevented by using a three-layer belt layer in which another belt layer is added on the outer side in the tire radial direction of the two cross belt layers.
Japanese Patent Laying-Open No. 2005-161964 (5th page, FIG. 1)

  However, the conventional method described above, that is, the method of preventing buckling by using three belt layers has the following problems. That is, it has been found that the method may not always prevent buckling completely.

  Therefore, an object of the present invention is to more reliably prevent the occurrence of buckling in a run-flat tire suitable for running on icy and snowy roads.

  In order to solve the above-described problems, the present invention has the following features. First, the first feature of the present invention is provided from the buttress portion (buttress portion 36) including the outer end in the width direction of the tread portion (tread portion 34) to the sidewall portion (sidewall portion 38) connected to the buttress portion. A side reinforcing layer (side reinforcing layer 40) having a crescent-shaped cross section along the tread width direction and the tire radial direction, two cross belt layers (for example, belt layer 20a), and at least one additional belt A run flat tire (run flat tire 1) including a composite belt layer (composite belt layer 24) having a layer (additional belt layer 22), wherein the side reinforcing layer has a cross section along the tread width direction and the tire radial direction. The thickness of the side reinforcing layer in the buttress portion increases from the buttress portion toward the sidewall portion. The ratio G1 / G2 thickness G2 of the side reinforcing layer in the wall portion is summarized in that at 0.79 or more.

  According to such a run-flat tire, since the ratio G1 / G2 of the thickness of the side reinforcing layer is 0.79 or more, the side reinforcing layer has a tread in the cross section along the tread width direction and the tire radial direction. It can suppress that the rigidity by the side wall part side becomes high with respect to the rigidity by the part side.

  That is, the run flat tire can suppress the tread portion from warping inward in the tire radial direction even when the internal pressure of the run flat tire is greatly reduced. Therefore, the run-flat tire functions as a run-flat tire suitable for running on icy and snowy roads, and can more reliably prevent the occurrence of buckling.

  The second feature of the present invention relates to the first feature of the present invention, and is the outer belt layer (cap layer 28) provided on the outer side in the tire radial direction of the composite belt layer, and both ends of the composite belt layer in the tread width direction. And a pair of end covering portions (layer layer 32) that respectively cover both ends of the outer belt layer.

  A third feature of the present invention relates to the second feature of the present invention, wherein the outer belt layer is disposed on the outer side in the tire radial direction of the first outer belt layer (first cap layer 26a) and the first outer belt layer. A second outer belt layer (second cap layer 26b) provided, and the end covering portion is provided on the outer side in the tire radial direction of the first covering portion (first layer layer 30a) and the first covering portion. The gist is to have a second covering portion (second layer layer 30b) provided.

  According to the features of the present invention, the run-flat tire is a run-flat tire suitable for running on icy and snowy roads, and can more reliably prevent buckling.

  Next, embodiments according to the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones.

  Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

[Embodiment]
In this embodiment, (1) configuration of run-flat tire, (2) detailed configuration of side reinforcing layer, (3) detailed configuration of composite belt layer, (4) comparative evaluation, (5) action and effect, (6 ) Other embodiments will be described.

(1) Configuration of Run Flat Tire FIG. 1 is a partially exploded perspective view including a cross section in the tread width direction of the run flat tire 1 in the embodiment of the present invention. The run-flat tire 1 is a studless tire suitable for running on icy and snowy roads. Hereinafter, each part which comprises the run flat tire 1 is demonstrated.

  Specifically, (1.1) bead portion, (1.2) carcass, (1.3) side reinforcing layer, (1.4) composite belt layer, (1.5) cap layer, (1.6) ) The layer layer will be described.

(1.1) Bead part As shown in Drawing 1, run flat tire 1 has a pair of bead parts 10 containing at least bead core 10a and bead filler 10b. Specifically, a steel cord or the like is used for the bead core 10a constituting the bead unit 10.

(1.2) Carcass
The run-flat tire 1 includes a carcass 12 that is folded from the tire radial inner side to the tire radial outer side around the bead core 10a.

  The carcass 12 is made of a carcass cord and rubber, and forms a skeleton of the run-flat tire 1.

  Between the bead core 10a and the carcass 12, a bead reinforcement layer 14 is disposed around the bead core 10a and folded back from the inner side in the tire radial direction to the outer side in the tire radial direction.

  Specifically, the bead reinforcement layer 14 is configured by impregnating a predetermined organic fiber cord with a rubber component. The predetermined organic fiber cord is preferably an aramid fiber.

  An inner liner 16, which is a highly airtight rubber layer corresponding to a tube, is provided on the inner side in the tire radial direction of the carcass 12 and the side reinforcing layer 40.

(1.3) Side Reinforcement Layer The run-flat tire 1 includes a side reinforcement layer 40 that reinforces the sidewall portion 38 on the inner side in the width direction of the bead reinforcement layer 14. The side reinforcing layer 40 functions as a side reinforcing layer of the run flat tire. In particular, the side reinforcing layer 40 has characteristics that are preferably used as the side reinforcing layer 40 of a run-flat tire for icy and snowy roads.

  (1.4) Composite Belt Layer The run-flat tire 1 includes a composite belt layer 24 having two crossing belt layers (belt layer 20a and belt layer 20b) and at least one additional belt layer 22.

(1.5) Cap layer
The run flat tire 1 includes a cap layer 28 that is provided outside the composite belt layer 24 in the tire radial direction and reinforces the composite belt layer 24.

  The cap layer 28 includes a first cap layer 26a and a second cap layer 26b provided on the outer side in the tire radial direction of the first cap layer 26a.

  The cap layer 28 is configured by impregnating a rubber component into a hybrid belt reinforcing cord including at least a high elastic organic fiber cord and a low elastic organic fiber cord. The high-elasticity organic fiber cord is preferably an aramid fiber, and the low-elasticity organic fiber cord is preferably a nylon fiber. The arrangement directions of the cords of the first cap layer 26a and the second cap layer 26b are different.

(1.6) Layer Layer The run-flat tire 1 includes a pair of layer layers 32 that respectively cover both end portions of the composite belt layer 24 and both end portions of the cap layer 28 in the tread width direction.

  The layer layer 32 has the 1st layer layer 30a and the 2nd layer layer 30b provided in the tire radial direction outer side of the 1st layer layer 30a.

  Similar to the cap layer 28, the layer layer 32 is configured by impregnating a rubber component into a hybrid belt reinforcing cord including at least a high elastic organic fiber cord and a low elastic organic fiber cord.

(1.7) Appearance of Run Flat Tire 1 The run flat tire 1 includes a tread portion 34 that contacts the road surface on the outer side in the tire radial direction of the cap layer 28. The tread portion 34 in the present embodiment constitutes a pattern for traveling on icy and snowy roads.

  The run flat tire 1 includes a buttress portion 36 that is formed between the tread portion 34 and the sidewall portion 38 and continues to the side end of the tread portion 34. Specifically, the run flat tire 1 includes a pair of buttress portions 36 on both sides of the tread portion 34 in the tread width direction.

  (2) Detailed Configuration of Side Reinforcement Layer A detailed configuration of the side reinforcement layer 40 provided on the inner side in the width direction of the bead reinforcement layer 14 will be described. FIG. 2 is a cross-sectional view of the run flat tire 1 in the tread width direction.

  The side reinforcing layer 40 becomes thicker from the buttress portion 36 toward the sidewall portion 38 in the cross section along the tread width direction and the tire radial direction.

  The ratio G1 / G2 between the thickness G1 of the side reinforcing layer 40 in the buttress portion 36 and the thickness G2 of the side reinforcing layer 40 in the sidewall portion 38 is 0.79 or more. The ratio G1 / G2 is more preferably 0.86 or more. The ratio G1 / G2 is more preferably 1.2 or less.

  The thickness G1 of the side reinforcing layer 40 in the buttress portion 36 is the side reinforcing layer of the buttress portion 36 in the cross section along the tread width direction and the tire radial direction in the run flat tire 1 in which the filling gas is filled with the standard internal pressure. The thickness is 40.

  Specifically, the thickness G1 of the side reinforcing layer 40 is the straight line of the side reinforcing layer 40 on the inner liner 16 side in a straight line that passes through the end of the buttress portion 36 on the side wall 38 and intersects the inner liner 16 perpendicularly. The thickness from the end to the end of the side reinforcing layer 40 on the carcass 12 side is shown.

  Note that the end of the buttress 36 is formed in a region showing a distance of 23 to 28% along the inner side in the tire radial direction from the outer end in the tire radial direction of the run flat tire 1 with respect to the section height SH. Is done.

  The section height SH is a distance from the outer end in the radial direction of the run flat tire 1 to the rim base line. The rim baseline is defined as the tire axial line that determines the rim diameter defined by the rim standards of JATMA (Japan Automobile Tire Association), TRA (American Tire and Rim Association) and ETRTO (European Tire and Rim Technical Organization). The

  The thickness G2 of the side reinforcing layer 40 in the sidewall portion 38 means the side of the sidewall portion 38 in the cross section along the tread width direction and the tire radial direction in the run flat tire 1 in which the standard internal pressure is filled with the filling gas. This is the thickness of the reinforcing layer 40. Specifically, the thickness G2 of the side reinforcing layer 40 is 42 to 49% from the tire radial direction outer side end portion of the run flat tire 1 along the tire radial direction inner side with respect to the section height SH. Side reinforcement from the end of the side reinforcing layer 40 on the inner liner 16 side to the end of the side reinforcing layer 40 on the carcass 12 side in a straight line that passes through the side wall portion 38 in the region indicating the distance and perpendicularly intersects the inner liner 16. Of the thickness of the layer 40, the largest value is shown.

(3) Detailed Configuration of Composite Belt Layer A detailed configuration of the composite belt layer 24 that is provided outside the carcass 12 in the tire radial direction and reinforces the carcass 12 will be described. Specifically, (3.1) the crossing belt layer and (3.2) the additional belt layer will be described.

(3.1) Crossing belt layer The crossing belt layer is composed of a belt layer 20a coupled to the outer side in the tire radial direction of the bead reinforcement layer 14 and a belt layer 20b disposed on the outer side in the tire radial direction of the belt layer 20a. Is done. The belt layer 20a and the belt layer 20b are configured by impregnating a predetermined organic fiber cord with a rubber component. The arrangement directions of the cords of the belt layer 20a and the belt layer 20b are different.

  (3.2) Additional Belt Layer The additional belt layer 22 is disposed on the outer side in the tire radial direction of the crossing belt layer. The additional belt layer 22 is configured by impregnating a predetermined organic fiber cord with a rubber component.

  The arrangement direction of the cord of the additional belt layer 22 is the same as that of the belt layer 20a or the belt layer 20b. Specifically, the intersection angle of the cord of the additional belt layer 22 with respect to the tire equator line CL is set to be larger than that of the cord constituting the belt layer 20a or the belt layer 20b.

(4) Comparative Evaluation Next, in order to further clarify the effect of the present invention, comparative evaluation performed using pneumatic tires according to the following comparative examples and examples will be described. Specifically, (4.1) Evaluation method and (4.2) Evaluation result will be described. In addition, this invention is not limited at all by these examples.

(4.1) Evaluation method Using five types of pneumatic tires, the rolling performance on ice was evaluated. Data on pneumatic tires were measured under the following conditions.

・ Tire size: 245 / 50R18
・ Rim wheel size: 18 × 8J
・ Internal pressure: 0kPa
-Vehicle type: Automobile or equivalent indoor testing machine (eg turntable)
-Tire configuration: Run-flat tire
Composite belt layer; cross belt layer (2 layers) + additional belt layer (1 layer)
・ Load condition: 640kg
・ Road surface condition: 0 ℃ (frozen road surface)
Measurement method: A run-flat tire that is in a freely rolling condition is placed on a disk-shaped road surface, and the presence or absence of buckling is measured by rotating the disk.

  The run-flat tires of the comparative example and Examples 1 to 3 are different in the number of cap layers and layer layers and the ratio G1 / G2.

(4.2) Evaluation Results The evaluation results of each run flat tire will be described with reference to Table 1.

    In the run flat tire according to the comparative example, buckling occurred. In the run flat tires according to Examples 1 to 3, buckling did not occur.

(5) Action / Effect As described above, according to the run-flat tire 1 according to the present embodiment, the thickness ratio G1 / G2 of the side reinforcing layer 40 is 0.79 or more, so the tread width direction And in the cross section along the tire radial direction, the side reinforcing layer 40 can suppress the rigidity on the side wall part 38 side from becoming too high with respect to the rigidity on the tread part 34 side.

  That is, the run flat tire 1 can suppress the tread portion from warping inward in the tire radial direction even when the internal pressure of the run flat tire 1 is greatly reduced. Therefore, the run-flat tire 1 functions as a run-flat tire suitable for running on icy and snowy roads, and can more reliably prevent buckling.

  The ratio G1 / G2 is more preferably 0.86 or more. According to this, the run-flat tire 1 can sufficiently increase the rigidity on the tread portion 34 side in the cross section along the tread width direction and the tire radial direction, so that the occurrence of buckling can be further reliably prevented.

  The ratio G1 / G2 is more preferably 1.2 or less. According to this, the side reinforcing layer 40 has no problem in manufacturing, and in the cross section along the tread width direction and the tire radial direction, it is possible to reduce the deviation of the weight balance toward the outer side in the tire radial direction. Even when it falls, the deformation | transformation of the side wall part 38 can be suppressed more effectively.

  In this embodiment, since the cap layer 28 and the layer layer 32 are provided, the run flat tire 1 can improve the rigidity of the tread portion 34. Therefore, the run flat tire 1 can more reliably prevent the occurrence of buckling.

  The cap layer 28 includes a first cap layer 26a and a second cap layer 26b, and the arrangement directions of the cords of the first cap layer 26a and the second cap layer 26b are different. Can further improve the rigidity of the tread portion 34.

  In this embodiment, since the layer layer 32 has the 1st layer layer 30a and the 2nd layer layer 30b, the rigidity of the edge part of the tread part 34 along a tread width direction can be improved. That is, the run flat tire 1 can effectively improve the rigidity of the tread portion 34 while suppressing the weight of the tire.

(6) Other Embodiments As described above, the contents of the present invention have been disclosed through the embodiments of the present invention. However, it is understood that the description and drawings constituting a part of this disclosure limit the present invention. Should not. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, the embodiment of the present invention can be modified as follows.

  In the embodiment described above, the run flat tire 1 is provided with a pattern for running on an icy and snowy road in the tread portion 34 as a run and flat tire for an icy and snowy road, but is not limited to this, for example, a normal pattern ( Summer patterns, etc.).

  In the embodiment described above, the composite belt layer is composed of two crossing belt layers and one additional belt layer. However, the present invention is not limited to this, and the additional belt layer is composed of a plurality of layers. May be.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

1 is a partially exploded perspective view of a run flat tire 1 according to an embodiment of the present invention. It is sectional drawing of the tire width direction of the run flat tire 1 which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Run flat tire, 10 ... Bead part, 10a ... Bead core, 10b ... Bead filler
12 ... carcass, 14 ... bead reinforcement layer, 16 ... inner liner,
20a, 20b ... belt layer, 22 ... additional belt layer, 24 ... composite belt layer,
26a, 26b ... second cap layer, 28 ... cap layer, 30a, 30b ... second layer layer,
32 ... Layer layer, 34 ... Tread part, 36 ... Buttress part, 38 ... Side wall part 40 ... Side reinforcement layer

Claims (3)

A side reinforcement layer provided from the buttress part including the width direction outer end of the tread part to the sidewall part connected to the buttress part, and having a crescent-shaped cross-sectional shape along the tread width direction and the tire radial direction;
A run flat tire comprising two cross belt layers and a composite belt layer having at least one additional belt layer,
In the cross section along the tread width direction and the tire radial direction, the side reinforcing layer becomes thicker from the buttress portion toward the sidewall portion,
A run flat tire in which a ratio G1 / G2 of the thickness G1 of the side reinforcing layer in the buttress portion and the thickness G2 of the side reinforcing layer in the sidewall portion is 0.79 or more.
An outer belt layer provided on the outer side in the tire radial direction of the composite belt layer;
2. The run-flat tire according to claim 1, further comprising: a pair of end covering portions that respectively cover both end portions of the composite belt layer and both end portions of the outer belt layer in the tread width direction.
The outer belt layer has a first outer belt layer and a second outer belt layer provided on the outer side in the tire radial direction of the first outer belt layer,
The run-flat tire according to claim 2, wherein the end covering portion includes a first covering portion and a second covering portion provided on the outer side in the tire radial direction of the first covering portion.