JP5292879B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire with improved high-speed durability.

  In general, a pneumatic tire has a structure in which a belt layer made of a steel cord is provided inside a tread portion. When this pneumatic tire runs at high speed, heat is generated by the belt layer being repeatedly bent by an external force applied from the road surface. When the generated heat is accumulated in the belt layer, the end portion of the belt layer causes separation, which causes a problem that the high-speed durability of the tire is lowered.

  Conventionally, as a countermeasure for solving such a problem, Patent Document 1 generates a belt layer by interposing a rubber layer made of a heat conductive rubber composition between an edge portion of the belt layer and an outermost carcass layer. It is proposed to release the heat generated outside the tire.

However, since the rubber layer of the heat conductive layer is only provided in the region of the outer end portion of the belt layer, there is a limit to the heat dispersion effect, which is sufficient particularly in tires that continuously run at high speed. There was a problem that it was not possible to demonstrate the durability.
JP 2004-359096 A (paragraph [0022], FIG. 7)

  An object of the present invention is to provide a pneumatic tire with improved high-speed durability.

To achieve the above object, the present invention passes over a carcass layer between the pair of left and right bead portions, the pneumatic tire of arranging the belt layer made of steel cords on the outer peripheral side of the carcass layer, laminated on the belt layer A heat conductive layer extending over the entire length in the width direction of the belt layer and extending in the vicinity of the surface of the sidewall portion from both ends in the width direction of the belt layer, the heat conductive layer is a tread portion and have a thermal conductivity of greater than rubber constituting the sidewall portion, the heat conductive layer is in a rubber having a strip-like heat conductive, 90 ° ± 45 ° with respect to the tire circumferential direction The end portion of the heat conducting layer located near the surface of the sidewall portion is formed of a cord layer embedded with a plurality of steel cords arranged in parallel with each other at an angle of Characterized in that from the surface of Oru portion located within a range of 3 mm.

  According to the pneumatic tire of the present invention, the heat generated in the belt layer during high-speed running is conducted to the sidewall portion by the heat conductive layer, and is efficiently released from the surface of the sidewall portion to the outside of the tire. Heat accumulation can be suppressed, and high-speed durability can be improved.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is an example of a pneumatic tire (pneumatic radial tire) according to an embodiment of the present invention.
This pneumatic tire (hereinafter simply referred to as “tire”) is constructed by mounting two carcass layers 3 made of organic fiber cords between a tread portion 1 and a pair of left and right beat portions 2 on the inside of the tire. Both ends of the carcass layer 3 are folded around the bead core 4 so as to sandwich the bead filler 5 from the inside to the outside of the tire.

  A belt layer 6 made of two steel cords is arranged on the outer peripheral side of the carcass layer 3 in the tread portion 1 so as to cross the cords between the layers, and the belt layer 6 has a certain width.

In such a tire, the heat conductive layer 9 is provided so as to be laminated at both end portions 6 a in the width direction of the belt layer 6 and extend from both end portions 6 a to the vicinity of the surface of the site wall portion 8.
The heat conductive layer 9 conducts heat generated in the belt layer 6 during high-speed running to the sidewall portion 8 without being accumulated in the belt layer 6, and can be discharged from the surface of the sidewall portion 8 to the outside of the tire. It has a higher thermal conductivity than the rubber that constitutes the tread portion and the sidewall portion.
As shown in FIG. 1, the inner end 9a of the heat conductive layer 9 may be arranged so as to be in contact with the outside in the thickness direction of the belt layer 6, or as shown in FIG. The belt layer 6 may be laminated and disposed so that both surfaces thereof are in contact with an intermediate portion in the thickness direction of the belt layer 6.
Further, in order to release heat from the surface of the sidewall portion 8 to the outside of the tire, the extended end portion 9b outside the heat conductive layer 9 extends from the surface of the sidewall portion 8 to the inside within a range of 3 mm or less. The extended end portion 9b of the heat conductive layer 9 may be exposed on the surface of the sidewall portion 8 as long as it is within this range, or may be inside.

By providing the heat conductive layer 9 in this manner, heat generated in the belt layer 6 during high speed running can be conducted to the sidewall portion 8 and efficiently discharged from the surface of the sidewall portion 8 to the outside of the tire. It is possible to suppress the accumulation of heat in this, thereby suppressing the rubber deterioration at the end of the belt layer and improving the high speed durability.
In addition, the provision of the heat conductive layer 9 increases the restraint of the belt layer 6, which is advantageous for enhancing the durability of the tire, and can improve road noise (R / N).

The length L (wrap amount L) of the inner end 9a on the belt layer side of the heat conductive layer 9 and the belt layer end 6a is preferably 10 mm or more. If it is smaller than 10 mm, heat may not be easily transferred from the belt layer 6 to the heat conductive layer 9 and stress may concentrate on the end portion 9a and the heat conductive layer 9 may be easily peeled off.
In this case, as shown in FIG. 3 and FIG. 4, the inner end portions 9 a of the heat conductive layers 9 stacked at both ends in the width direction of the belt layer 6 are stacked along the belt layer 6 while being stacked on the belt layer 6. If the heat conductive layer 9 is extended over the entire length in the width direction of the belt layer 6, it is advantageous to efficiently dissipate heat generated in the belt layer 6. This is also advantageous in increasing the restraint of the layer 6 and increasing the durability of the tire.

The extended end portion 9b of the heat conductive layer 9 is located outside the range of 10 mm and within the range of 30 mm from the tire maximum width position 10 to the tire radial direction outside in the tire radial direction, or from the tire maximum width position 10. It is located in the range of 10 mm or more inward in the tire radial direction.
In other words, the extension end portion 9b of the heat conductive layer 9 has a tire radial distance H from the tire maximum width position 10 of 10 mm or more and 30 mm or less on the tire radial direction outer side, or the distance H is the tire radial inner side. 10mm or more.
When the distance H is smaller than 10 mm, the heat conductive layer 9 is easily peeled off because the distance H approaches the center of deflection in the tire radial direction.
When the distance H is larger than 30 mm on the outer side in the tire radial direction, the heat radiation area is reduced and the heat radiation efficiency is lowered.
The extended end 9 b of the heat conductive layer 9 may extend to the bead portion 2 and be wound inside the bead core 4.

In the present invention, in order to efficiently release the heat generated in the belt layer 6 during high-speed running from the surface of the sidewall portion 8 to the outside of the tire via the heat conductive layer 9, the heat conductivity of the heat conductive layer 9 is 0. It is preferably 3 kcal / mh ° C. or higher.
In order to verify this, the inner end portion 9a of the heat conductive layer 9 is laminated on the outer side in the thickness direction of the belt layer 6, and the extended end portion 9b of the heat conductive layer 9 is arranged with respect to the tire radial direction. Is located at a location 10 mm away from the tire maximum width position 10 in the radial direction of the tire, and the extended end portion 9 b of the heat conductive layer 9 is located at a location 2 mm from the surface of the sidewall portion 8 to the inside. The side wall portion 8 after 30 minutes when the temperature of 6 is 90 ° C. and the thermal conductivity of the heat conductive layer 9 is 0.1, 0.2, 0.3, 0.4, 0.5 kcal / mh ° C. The surface temperature was measured and the results are shown in Table 1.

As is clear from Table 1, when the thermal conductivity of the heat conductive layer 9 is less than 0.3 kcal / mh ° C., the temperature of the surface of the sidewall portion 8 does not rise to a desired temperature, and the belt layer 6 It is not possible to expect the effect of efficiently releasing the heat generated in the above through the heat conductive layer 9 from the surface of the sidewall portion 8 to the outside of the tire.
On the other hand, when the thermal conductivity of the thermal conductive layer 9 is 0.3 kcal / mh ° C. or higher, the temperature of the surface of the sidewall portion 8 rises to a desired temperature. The effect of efficiently discharging from the surface of the sidewall portion 8 to the outside of the tire via the heat conductive layer 9 can be sufficiently expected.

For example, as shown in FIG. 5, the thermal conductive layer 9 is a cord layer 22 in which a plurality of cords 21 having thermal conductivity are embedded in parallel in a band-like rubber 20 having thermal conductivity. Or a rubber composition having thermal conductivity, or a viscous material such as a sealant material.
As the cord 21 constituting the cord layer 22, a metal cord such as steel or copper can be used.
When a metal cord layer using such a metal cord is used as the cord layer 22, it is desirable in that it has a very high thermal conductivity and can improve the damage resistance of the tire, and a steel cord layer is particularly desirable. .
Examples of the rubber composition having thermal conductivity include a rubber composition having a high carbon black content and a rubber composition containing metal powder or carbon fiber.
The thermal conductivity of a viscous material such as a rubber composition was measured by pressing vulcanization at 160 ° C. for 20 minutes in a 15 cm × 15 cm × 1 cm mold to produce a test piece (rubber sheet). The thermal conductivity was measured with a heater QTM-DII.
When the heat conductive layer 9 is composed of a metal cord layer, it should not be exposed to the surface of the sidewall portion 8 from the viewpoint of rust prevention of the extended end portion 9b of the heat conductive layer 9 on the side wall portion side. Is preferred.
The extending directions of the cords 21 are arranged in parallel with each other at an angle of 90 ° ± 85 ° with respect to the tire circumferential direction, and within an angular range of 90 ° ± 45 ° with respect to the tire circumferential direction. If so, it is advantageous in shortening the heat conduction distance and efficiently conducting the heat generated in the belt layer 6 to the surface of the sidewall portion 8.

  As the metal cord constituting the metal cord layer, it is desirable to use a single wire rather than a stranded wire in order to minimize the change in rigidity of the tire. Further, in order to prevent the heat transfer effect of the metal cord layer from becoming insufficient, the number of ends of the metal cord (number of cords to be driven) and the wire diameter are set to 10 pieces / 50 mm or more and 0.1 mm or more, respectively, and the rigidity of the tire is increased. In order not to increase the riding comfort and to increase, it is desirable that the number is 30/50 mm or less and 0.3 mm or less, respectively.

  The surface of the sidewall portion 8 in the region where the extended end portion 9b of the heat conductive layer 9 is disposed may be smooth like a general tire, but dimples are formed on the surface, or the surface is wavy. It is desirable to form. By doing in this way, since the surface area of the side wall part 8 can be enlarged, the heat dissipation to the exterior of the tire of the heat | fever which the heat conductive layer 9 conducted can be improved.

A tire of 225 / 45ZR18 93Y is incorporated into a rim of 18 × 71 / 2JJ, the air pressure is 220 kPa, and high speed durability, road noise (R / N), and trauma resistance are compared with Comparative Examples 1 and 2 and Examples 1 to 14. Compared.
The basic structure of the sidewall portion 8 is that shown in FIG. 1, and in Table 2, in Table 2, the inner end portion 9a of the heat conductive layer 9 is disposed on the outer side in the thickness direction of the belt layer 6, Table 3 shows a case where the inner end portion 9 a of the heat conductive layer 9 is laminated and disposed at the center portion in the thickness direction of the belt layer 6.
In Tables 2 and 3, in Comparative Examples 1 and 2, the heat conductive layer 9 is composed of a cord layer made of nylon cord, and in Examples 1 to 14, the heat conductive layer 9 is composed of a steel cord layer made of steel cord, The angles formed by the steel cord with respect to the tire radial direction were 30 ° and 60 °.
The length (lap amount) for laminating the heat conductive layer 9 on the belt layer 6 was 5 mm and 20 mm, and the case where the belt layer 6 was laminated over the entire length in the width direction (FULL).
In addition, the extended end portion 9b of the heat conductive layer 9 was positioned at 0 mm and 20 mm on the outer side in the tire radial direction from the tire maximum width position 10 with respect to the tire radial direction.
Further, the extended end portion 9b of the heat conductive layer 9 was set to 2 mm and 4 mm from the surface of the sidewall portion 8 to the inside.
Further, the surface of the sidewall portion 8 where the extended end portion 9b of the heat conductive layer 9 is located is a normal curved surface and corrugated.
A steel cord having a thermal conductivity of 80 kcal / mh ° C. was used as a steel cord constituting the steel cord layer, and a rubber having a thermal conductivity of 0.4 kcal / mh ° C. was used as a rubber constituting the steel cord layer.
These 16 types of tires were evaluated for high-speed durability, road noise (R / N), and damage resistance by the following measurement methods, and the results are shown in Tables 2 and 3.

[High-speed durability]
Using a high-speed drum tester, the speed was increased every 10 minutes, and the speed until the tire broke down was compared.
[Road noise (R / N)]
The results of the sensory evaluation were compared by running at 80 km / h.
[Trauma resistance]
We entered a curb with a height of 50 mm at an angle of 10 °, and increased the speed each time the number was increased, and compared the speed until the tire broke down.
The evaluation is indicated by an index with the measured value of the comparative example being 100, and the larger the index value, the better the high-speed durability, road noise (R / N), and scratch resistance.

From the experimental results shown in Tables 2 and 3, the pneumatic tires (Examples 1 to 14) of the present invention are all excellent in high-speed durability, road noise (R / N), and trauma resistance as compared with the comparative tires. I understand that
The present invention is widely applied to all pneumatic tires such as a tube tire, a tubeless tire, and a run flat tire.

1 is a half sectional view of a pneumatic radial tire according to an embodiment of the present invention. 1 is a half sectional view of a pneumatic radial tire according to an embodiment of the present invention. 1 is a half sectional view of a pneumatic radial tire according to an embodiment of the present invention. 1 is a half sectional view of a pneumatic radial tire according to an embodiment of the present invention. It is explanatory drawing of a code layer.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Tread part, 2 ... Bead part, 3 ... Carcass layer, 4 ... Bead core, 5 ... Bead filler, 6 ... Belt layer, 6a ... End part, 8 ... Side wall part, 9 ... ... heat conduction layer, 9a ... inner end, 9b ... extended end, 10 ... tire maximum width position, 20 ... rubber, 21 ... cord, 22 ... cord layer.

Claims (10)

In a pneumatic tire in which a carcass layer is stretched between a pair of left and right bead parts, and a belt layer made of a steel cord is disposed on the outer peripheral side of the carcass layer,
A thermal conductive layer is provided that extends over the entire length of the belt layer in the width direction while being laminated on the belt layer, and extends from both ends of the belt layer in the width direction to the vicinity of the surface of the sidewall portion,
The thermally conductive layer may have a thermal conductivity of greater than rubber which constitutes the tread portion and sidewall portions,
The thermal conductive layer is a cord in which a plurality of steel cords arranged in parallel with each other at an angle of 90 ° ± 45 ° with respect to the tire circumferential direction are embedded in a rubber having a plate-like thermal conductivity Composed of layers,
The end portion of the heat conductive layer located in the vicinity of the surface of the sidewall portion is located within a range of 3 mm from the surface of the sidewall portion.
A pneumatic tire characterized by that.   The pneumatic tire according to claim 1, wherein the heat conductive layer is laminated and disposed on an outer side in the thickness direction of the belt layer.   The pneumatic tire according to claim 1, wherein the heat conductive layer is laminated and disposed in an intermediate portion in a thickness direction of the belt layer. The end portion of the heat conductive layer located in the vicinity of the surface of the sidewall portion is located within a range of 10 mm to 30 mm from the tire maximum width position to the tire radial direction outside in the tire radial direction, or the tire maximum width. The pneumatic tire according to any one of claims 1 to 3 , wherein the pneumatic tire is located in a range of 10 mm or more from a position to an inner side in a tire radial direction. The pneumatic tire according to any one of claims 1 to 4, wherein the steel cord is a single wire. The pneumatic tire according to any one of claims 1 to 5, wherein the number of ends of the steel cord is 10 to 30 pieces / 50 mm. The pneumatic tire according to any one of claims 1 to 6, wherein a wire diameter of the steel cord is 0.1 to 0.3 mm. The thermal conductivity of the thermal conductive layer is 0.3 kcal / mh ° C. or higher.
The pneumatic tire according to any one of claims 1 to 7 , characterized in that The pneumatic tire according to any one of claims 1 to 8 , wherein a plurality of dimples are formed on a surface portion of the sidewall portion where an end portion in the extending direction of the heat conductive layer is located. The pneumatic tire according to any one of claims 1 to 8 , wherein a surface portion of the sidewall portion where an end portion in the extending direction of the heat conductive layer is located is formed in a wave shape.

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