JP2000309211A - Run-flat pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce weight while maintaining run-flat durability. SOLUTION: This run-flat tire has a tread width TW smaller than a rim width RW of a standard rim (TW/RW<=1.03), so that the tread width TW becomes smaller than that of a normal run-flat tire and thus weight reduction is achieved. Accordingly, fuel efficiency and ride comfort of a vehicle are improved. Reduction of the tread width, however, makes a shoulder portion 28 contact the ground when the tire is punctured and an internal pressure of the tire becomes 0 kPa. Since a side rubber 34 whose wear resistance is higher than that on a bead portion 32 (a bead rubber 36) is provided, a ply is prevented from being cut due to wear of the shoulder portion 28 while running with a flat tire, as well as a run-flat durability is maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic run-flat tire having a rubber reinforcing layer on an inner surface of a side surface, and more particularly to a pneumatic run-flat tire which is reduced in weight while maintaining run-flat durability.

[0002]

2. Description of the Related Art Run-flat running is possible with pneumatic tires, that is, when a tire is punctured and the tire internal pressure is 0 kP.
Even if a is reached, a tire (hereinafter, referred to as a run-flat tire) that can travel with a certain distance without any worry has been conventionally manufactured.

[0003] As shown in FIG.
No. 00 is known in which a relatively hard reinforcing rubber layer 106 having a substantially crescent shape in cross section is arranged on the inner surface of the carcass layer 104 of the side surface portion (here, from the shoulder portion to the bead portion) 102 and reinforced. I have. Further, the run flat tire 100 has a structure in which a plurality of belt layers 108 made of a metal cord are firmly fixed to also prevent puncture.

[0004] Therefore, when the tire is punctured and the air escapes, the side portion 1 reinforced with the reinforcing rubber layer 106 or the like is used.
The load is supported by the inherent stiffness 02, and the vehicle can run flat for a predetermined distance to the safety zone.

[0005] The side portion 102 of the run flat tire
Since the rubber does not contact the ground, rubber having low rolling resistance is used in consideration of the rolling properties of the tire.

[0006]

The run-flat tire 100 as described above is reinforced by a relatively high-hardness reinforcing rubber layer 106 on the inner surface of the side surface portion 102, so that it is compared with a normal tire having no reinforcing rubber. Weight increases. As a result, the fuel efficiency of the vehicle is deteriorated due to an increase in rolling resistance, and the riding comfort is deteriorated due to an increase in unsprung weight.

[0007] In order to solve these inconveniences, it is desired to reduce the weight of the run flat tire.

[0008] If the mass of the reinforcing rubber 106 is reduced based on the above demand, the durability in run-flat running (hereinafter referred to as run-flat durability) is significantly reduced.

Further, as a method for reducing the weight of a run flat tire, a tread portion 1 having a high proportion in the entire tire mass is used.
A method of narrowing the tread width of No. 10 is conceivable. In this case, as shown in FIG. 5, since the tread width is narrow,
When the tire is punctured and the tire internal pressure becomes 0 kPa, the side surface portion 102 (shoulder portion or the like) comes into contact with the ground. As a result, before the reinforcing rubber layer 106 is broken,
There was a disadvantage that the ply was broken due to the wear of the rubber having a low abrasion resistance disposed at the ground portion of No. 02, and the run flat durability was reduced.

[0010] The present invention has been made to solve the above problems, and an object of the present invention is to provide a pneumatic runflat tire that is reduced in weight without reducing runflat durability.

[0011]

In order to achieve the above object, according to the present invention, a belt layer and a tread layer are provided on an outer peripheral side of a carcass layer straddling a toroid between a pair of beads, A pneumatic runflat tire provided with a side surface portion continuous with the tread layer and provided with a rubber reinforcing layer on the inside of the carcass layer in the tire rotation axis direction, which is applied according to the size of the runflat tire. When the rim width of the standard rim is RW and the tread width of the run flat tire is TW, TW / RW ≦ 1.03
And a rubber having higher wear resistance than other portions is arranged on a ground contact portion which is outside the carcass of the side surface portion and is continuous from the tread side end to the bead side.

The operation of the first aspect of the present invention will be described.

In the pneumatic run flat tire according to the present invention, the tread width (TW / RW) with respect to the rim width RW of the standard rim applied according to the tire size is set to a normal run flat tire (TW / RW ≧ 1.05). ) (TW / RW ≦ 1.03), so that the weight of the tire is reduced.

[0014] Since the tread width of the tire is narrow, when the tire is punctured and the tire internal pressure becomes 0 kPa, the side surface portion comes into contact with the ground. However, since rubber having higher abrasion resistance than other side portions is used for the ground portion (shoulder portion or the like) from the tread side end to the bead side in the side portion, the side portion (ground portion) is used before the reinforcing rubber layer is broken. The run-flat durability is not impaired by the breakage of the ply or the like due to the wear of the rubber disposed in the portion (2).

Accordingly, the weight of the run flat tire can be reduced without impairing the run flat durability.

According to a second aspect of the present invention, the grounding portion includes:
It is a portion extending from the tread side end to the tire maximum width portion.

The operation of the second aspect of the present invention will be described.

The tread width TW and the rim width RW
It changes depending on the ratio and load. However, the ground contact portion during run flat running does not exceed the tire maximum width portion. Therefore, the portion from the tread side end portion to the tire maximum width portion outside the carcass on the side surface portion is regarded as a ground contact portion, and rubber having higher wear resistance than other portions (bead side than the contact portion) is disposed. This ensures run flat durability. In addition, it is possible to suppress the rolling resistance of the run-flat tire by arranging a rubber having a low rolling resistance on the other part of the side part that is not likely to be grounded.

According to a third aspect of the present invention, the rubber has a carbon nitrogen surface area in a range of 80 to 160 m ² / g.

The operation of the invention will be described.

In rubbers generally used for tires, the carbon nitrogen surface area is proportional to the wear resistance. Therefore, as the value of the carbon nitrogen surface area increases, the wear resistance of the tire also improves. Here, since the carbon nitrogen surface area of the rubber disposed on the side surface of the normal tire (including the run-flat tire according to the conventional example) is 80 m ² / g or less, run-flat running is performed by reducing the tread width. If the carbon nitrogen surface area of the rubber disposed at the side portion (the range from the tread side end to the maximum width portion of the tire) that occasionally touches the ground is 80 m ² / g or more, it is more wear resistant than the other portion of the side portion. The nature becomes high. Therefore, it is possible to reduce the weight of the tire while maintaining the run flat durability.

Further, when the carbon nitrogen surface area of the rubber is 160 m ² / g or more, the fluidity of the raw rubber is remarkably deteriorated, and the productivity (particularly extrusion) of the tire is deteriorated. Therefore, carbon nitrogen surface area 1
By being not more than 60 m ² / g, a predetermined tire productivity can be secured.

The invention according to a fourth aspect is characterized in that the rubber is a tread rubber disposed on the tread layer.

The operation of the fourth aspect of the present invention will be described.

The use of the rubber for the tread also reduces the types of rubber to be manufactured and facilitates manufacturing.

According to a fifth aspect of the present invention, the rubber is a tread rubber disposed on the tread layer.

The operation of the invention will be described.

By arranging the tread rubber on the contact portion of the side surface that contacts the ground during run flat running, the wear resistance of the contact portion is improved. As a result, run flat durability is ensured. In addition, the reduction in the types of rubber used facilitates the production.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A pneumatic run flat tire according to a first embodiment of the present invention will be described in detail. Hereinafter, the present embodiment will be described with reference to FIGS.

As shown in FIG.
In the rim assembly 10, a pneumatic run flat tire (hereinafter, referred to as a run flat tire) 14 is mounted on a rim 12.

As shown in FIG. 1, a run-flat tire 14 mounted on a rim 12 includes a pair of bead cores 16.
It has a toroidal carcass 18 spanning between them.

A two-layer belt layer 20 and a belt reinforcing layer 22 are disposed radially outside the carcass 18.
A tread portion 26 made of tread rubber 24 is disposed radially outside the belt layer 20 and the belt reinforcing layer 22.

A shoulder portion 28, a side portion 30, and a bead portion 32 are provided on the outer side of the carcass 18 in the tire width direction and continuous with the tread portion 26 toward the bead core 16. For convenience of explanation, the shoulder portion 28 and the side portion 3
0, the bead portion 32 is collectively called a side surface portion.

A side rubber 34 is arranged from the shoulder portion 28 to the tire maximum width position of the side portion 30, and a bead rubber 36 is arranged from the tire maximum width position to the bead portion 32.

Here, the side rubber 34 is a bead rubber 3
Rubber having a higher abrasion resistance than 6, for example, having a large carbon nitrogen surface area value. The bead rubber 36 is a rubber having a low rolling resistance.

On the inner side in the tire width direction of the carcass 18 on the side surface, there is provided a side rubber reinforcing layer 38 having a substantially crescent-shaped cross section and supporting the load, and the side rubber reinforcing layer 38 and the carcass 18 are arranged from above. An inner liner 40 is provided to cover.

Here, the side rubber reinforcing layer 38 is made of a relatively hard rubber having a higher hardness than the bead rubber 36.

Incidentally, the run flat tire 14 is such that the tread width TW of the tread portion 26 with respect to the rim width RW of the rim 12 is a normal run flat tire (TW / RW ≧ 1.
05) (TW / RW ≦ 1.03).

The rim width referred to here is a standard rim (or “Appr”) in an applicable size described in the following standard.
oved Rim ”,“ Recommended Rim ”).

The rim includes a rim that is officially attached to the vehicle at the vehicle manufacturer and the place of use or production of the vehicle, as well as a standard rim (or an applicable size) described in the following standards. , “Approved Rim”, ”
Recommended Rim ") is commonly used.

The standard is determined by an industrial standard effective in a region where the tire is manufactured or used.
For example, in the United States ¨The Tire and Rim Assoc
iation Inc.'s Year Book. and in Europe ¨The Eu
ropean Tire and Rim Technical Organization Stand
ards Manual¨, which is specified in Japan in the “JATMA Year Book¨” of the Japan Automobile Tire Association.

The tread width TW referred to here is an internal pressure of 180 kPa, and the 1999 edition “JATMA Year Boo”
The maximum tire width (axial width) at the contact portion of the tread portion 26 in the run flat tire 14 mounted on the standard rim corresponding to the tire size specified in k¨ and loaded with 88% of the maximum load capacity. It is.

The operation of the pneumatic run flat tire 14 thus configured will be described.

The pneumatic run-flat tire 14 thus formed is mounted on an automobile and travels to
The following effects are obtained.

During normal running (prescribed internal pressure), only the tread portion 26 comes into contact with the ground, and the side portions (such as the shoulder portion 28) do not come into contact with the ground.

On the other hand, the tire punctured and the tire internal pressure became zero.
FIG. 2 shows a state in which kPa (run flat running) has been reached. The tread width TW with respect to the rim width RW of the run flat tire 14 is a normal run flat tire (TW / RW ≧
1.05) (TW / RW ≦ 1.03),
A portion of the side portion (shoulder portion 28) near the belt end is grounded. Here, a side rubber 34 is provided on the shoulder portion 28.
Is disposed, the wear resistance is superior to that of the bead rubber 36 disposed on the other portion of the side surface portion (bead portion 32 side of the tire maximum width position). Therefore, it is possible to prevent the side portion (shoulder portion 28) from being worn and the ply from breaking while the side rubber reinforcing layer 38 is running flat while supporting the load. That is, the run flat durability of the run flat tire 14 is prevented from being reduced.

On the other hand, the tread width TW with respect to the rim width RW of the tread portion 26 which accounts for a large proportion of the entire mass of the run flat tire 14 is smaller than that of a normal run flat tire (TW / RW ≦ 1.03). Is reduced, and the fuel efficiency of the vehicle equipped with the run flat tire 14 is improved. Further, the unsprung weight is reduced, and the riding comfort of the vehicle is improved.

Further, since the bead rubber 36 disposed from the tire maximum width position of the side portion 30 to the bead portion 32 is a rubber having low rolling resistance, the rolling resistance of the run flat tire 14 is suppressed.

Next, a run flat tire 14 according to a second embodiment of the present invention will be described with reference to FIG. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

The feature of the run flat tire 14 of this embodiment is that the side rubber 34 is arranged not only from the shoulder portion 28 to the maximum width position of the side portion 30 but also to the tread portion 26.

By configuring the run flat tire 14 as described above, the weight of the tire can be reduced and the run flat durability can be improved. Further, the number of types of rubber provided for manufacturing the run flat tire 14 is reduced, and the manufacturing becomes easy.

In the present embodiment, the side rubber 34 is arranged on the tread portion 26. On the contrary, the tread rubber 24 extends from the shoulder portion 28 to the tire maximum width position of the side portion 30.
(See FIG. 1). (Test Example) In order to confirm the above action, the following test was conducted.

The tires used in the test are shown in FIG. 5 as a comparative example tire in which the tread width is smaller than usual in the conventional example (the side portion 102 is formed of one kind of rubber), and the example tire. In the structure, the structure A is a tire having the same structure as the first embodiment, and the structure B is a tire having the same structure as the second embodiment. That is, the tires have the same shape but differ only in the arrangement and type of rubber.

In this test, the dimensions of all tires are as follows.

Tire size: 225 / 60R16 Tread width: 163 Rim size: 16 × 6.5JJ Rim width: 165 Therefore, TW / RW ≦ 1.03 for all tires.

In Table 1, the compounding of the rubber in the comparative tire refers to the compounding of the rubber disposed on the side surface 102. This composition is also the composition of the bead rubber 36 in the example tire. The compounding of the rubber described in the example tire means the compounding of the side rubber 34. In the rubber compounding, the ratio of NR (natural rubber), BR (butadiene rubber), and SBR (styrene butadiene rubber) is indicated by a par sensor.

The run-flat durability is measured by assembling the above tires on a standard rim, mounting the tire on one of the front tires of the vehicle, removing the valve core to reduce the internal pressure to 0 kPa, and then proceeding straight at a speed of 80 to 100 km / h. The vehicle traveled continuously and was measured by the distance traveled until the failure occurred. The run flat durability was calculated by setting the running distance of the comparative tire to 100.
It indicates that the numerical value is good. The weight is 1 weight of a tire of a type having a normal tread width (see FIG. 4) (hereinafter referred to as a conventional tire).
It is represented by an exponent notation of 00, indicating that the numerical value is large.

[0058]

[Table 1]

As shown in the test results in Table 1, the tires of Examples 1 to 5 had a carbon nitrogen surface on a part of the side surface (shoulder or the like) that touches the ground during run-flat running as compared with the tire of Comparative Example 1. It was confirmed that the run rubber durability was improved because the side rubber having a large value of (carbon N ₂ SA) was arranged.

The tires of Examples 1 to 5 are slightly heavier than the tires of Comparative Example 1, but are confirmed to be lighter than the conventional tires (normal tread width type). Was.

[0061]

The pneumatic runflat tire according to the present invention achieves weight reduction by making the tread width of the runflat tire narrower than the rim width of the standard rim, and improves the fuel efficiency of a vehicle equipped with the runflat tire. And improved ride comfort.

On the other hand, since the tread width is reduced, rubber having higher abrasion resistance than other portions of the side portion is used for the contact portion of the side portion that contacts the ground during run flat running, so that run flat durability is maintained. Can be.

[Brief description of the drawings]

FIG. 1 is a sectional view of a pneumatic run-flat tire according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a run-flat running state of the pneumatic run-flat tire according to the first embodiment of the present invention.

FIG. 3 is a sectional view of a pneumatic run-flat tire according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a run-flat running state of a pneumatic run-flat tire according to a conventional example.

FIG. 5 is a cross-sectional view showing a run-flat running state when a tread width is reduced in a pneumatic run-flat tire according to a conventional example.

[Explanation of symbols]

 Reference Signs List 10 Pneumatic run flat tire 12 Rim (standard rim) 14 Pneumatic run flat tire 28 Shoulder part (side part) 30 Side part (side part) 32 Bead part (side part) 34 Side rubber (rubber)

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) B60C 13/00 B60C 13/00 E

Claims (5)

[Claims] 1. A belt layer and a tread layer are provided on the outer peripheral side of a carcass layer straddling a toroid between a pair of beads, and a side portion continuous with the tread layer is provided.
A pneumatic run flat tire having a rubber reinforcing layer provided on an inner side of the carcass layer in a tire rotation axis direction, wherein a rim width of a standard rim applied according to a size of the run flat tire is RW, and a run flat tire. Where TW / RW ≦ 1.03, where TW is the tread width of the tread, the abrasion resistance of the ground contact portion outside the carcass on the side surface portion and continuing from the tread side end to the bead side is higher than other portions. Pneumatic run-flat tires characterized by high rubber distribution. 2. The pneumatic run-flat tire according to claim 1, wherein the ground contact portion is a portion extending from a tread side end portion to a tire maximum width portion. 3. The pneumatic run-flat tire according to claim 1, wherein the rubber has a carbon nitrogen surface area in a range of 80 to 160 m ² / g. 4. The pneumatic run-flat tire according to claim 1, wherein the rubber is also arranged on the tread layer. 5. The pneumatic run-flat tire according to claim 1, wherein the rubber is tread rubber disposed on the tread layer.