JP2000043519A - Assembly of tire and rim - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reinforce a contact part by setting a ratio of a rubber thickness up to a carcass at a specified point to a tire thickness up to an outer surface of the tire to be a specified value, setting the rubber thickness to be more than a specified value, and setting the rubber thickness of an area by specified formulae I to IV on a tread part side and on a bead part side from the specified point. SOLUTION: The ratio dA/DA of the rubber thickness dA up to a carcass at an upper intersection A with an inner cavity surface of a tire to the tire thickness DA to the outer surface of the tire is set to be 0.2 to 0.6 mm, and the rubber thickness dA is set to be not less than 2.0 mm. The ratio dB/DB of the rubber thickness dB at a lower intersection B to the tire thickness DB is set to be 0.2 to 0.6 mm, and the rubber thickness dB is set to be not less than 2.0 mm. The distance LA from the upper intersection A to a tread part side is determined by the formula I; LA 1=0.65.Kab, the area EA is determined by the formula II; LA2=0.30.Kab on the bead part side, the distance LB1 on the tread part side is determined by the formula III; LB1=0.65.Kab, and the area EB is determined by the formula IV; LB2=0.30.Kab on the bead part side. In the formulae, Kab is determined by a specified formula. The rubber thickness di is not less than 2.0 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an assembly of a tire and a rim having run-flat performance that allows a tire to run for a certain distance even when air is leaked from the tire.

[0002]

2. Description of the Related Art There is a demand for a tire having a so-called run-flat performance that enables the vehicle to continue running even when the internal pressure of the tire is reduced due to puncture or the like.

[0003] In this type of tire, conventionally, for example, a core-like support made of an elastic material or the like is mounted inside the tire, or a high-hardness rubber reinforcing layer is provided on the inner surface of the sidewall portion. The tire load acting on a puncture or the like is supported to reduce vertical deflection, thereby suppressing tire structural destruction.

However, in the case of using a support, the weight increases with the increase in the number of parts, and a special technique is required to set the support when assembling the rim.
Moreover, the use of special rims often necessitates standard changes. Also, those provided with a rubber reinforcing layer, in order to reduce the vertical deflection of the tire, it is necessary to be extremely thick in a wide area around the tire maximum width point near the bending point,
Therefore, this also cannot avoid a large increase in weight and impairs rolling resistance. In addition, the rim is easily detached at the time of puncture due to the increase in rigidity of the sidewall portion, so that a special rim is often used.

[0005] Further, since these tires reduce the vertical deflection, it is difficult for the driver to notice the air leakage, and the driver can continue high-speed running with a normal driving feeling.
Further, when the steering wheel is operated suddenly, there is a danger that the control of the vehicle body is sometimes lost and a large accident occurs.

In view of the above circumstances, the inventor of the present invention has proposed not to suppress the vertical deflection of the tire but to execute the tire in a flat deformation state Y at an internal pressure of 0 shown in FIG. It has been found that suppressing the destruction itself is preferable for maintaining tire performance during normal driving and preventing accidents during run-flat driving.

As a result of repeated studies on the mechanism of tire destruction in the deformed state Y, as shown in FIG. 4, in the deformed state Y, the side wall portion Z is folded up and down at the rim flange upper end position RF to make contact. Therefore, during traveling, the upper and lower folded portions Z1 and Z2 are strongly rubbed at the contact portion J, causing wear and heat generation. Then, it has been found that the rubber on the inner surface of the tire is worn or peeled off due to the abrasion and heat generation, so that the carcass is exposed and the carcass are directly rubbed together, resulting in fatal damage that the carcass cord is broken. did.

[0008] In order to suppress the tire destruction based on this mechanism, it is necessary to protect the carcass from abrasion and heat generation at the contact portion J. The simplest means is to increase the thickness of the rubber under the carcass, By making it difficult for carcasses to come into contact with each other, it has been found that the mileage before tire breakdown can be greatly improved.

That is, the present invention is based on the fact that a thin protective rubber layer is provided inside the inner liner to strengthen only the contact portion, so that the driver can recognize the air leak by the deformation of the tire, It is an object of the present invention to provide a tire and rim assembly capable of improving run-flat performance without impairing various performances such as tire weight, rolling resistance, and rim detachability.

[0010]

According to one aspect of the present invention, there is provided a tire and rim assembly comprising a pneumatic tire and a rim having a bead seated thereon. The pneumatic tire includes a carcass extending from the tread portion to the bead core of the bead portion through the sidewall portion, an inner liner arranged along the inner surface of the carcass, and a tire cavity arranged along the inner surface of the inner liner. A heel point extending in a radial direction through a bead heel point where the rim sheet surface and the flange surface of the rim intersect with each other in a tire meridian section in a measurement internal pressure filled state filled with a standard internal pressure and having a protective rubber layer forming a surface. The rubber thickness dA to the carcass and the tire thickness to the tire outer surface at the upper intersection A where the radius line M intersects the tire lumen surface on the tread side. The ratio dA / DA of the DA is 0.2
0.6, and the rubber thickness dA is 2.0 mm or more, and the rubber thickness dB up to the carcass at the lower intersection B where the heel point radius line M intersects the tire lumen surface at the bead portion side and the tire outer surface. The ratio dB / DB with the tire thickness DB is 0.2 to
0.6, and the rubber thickness dB is 2.0 mm or more, and a middle intersection where a tire axial direction line passing through an intermediate height point e between the upper intersection A and the lower intersection B intersects the tire lumen surface. C
The ratio dC / DC between the rubber thickness dC up to the carcass and the tire thickness DC up to the tire outer surface is 0.4 to 0.6, and the rubber thickness dC is 3.0 mm or more. A point A1 separated from a distance LA1 represented by the following formula (1) on the tread portion side along the tire lumen surface around the intersection A
And an upper area EA between the bead portion side and a point A2 separated from the distance LA2 represented by the formula (2), and the following tread portion side (3) along the tire lumen surface around the lower intersection B as a center.
The rubber thickness di to the carcass at each position i in the lower region EB between the point B1 away from the distance LB1 represented by the formula and the point B2 away from the distance LB2 represented by the formula (4) on the bead portion side, and the tire outer surface. Ratio to the tire thickness Di up to di / D
i is 0.2 to 0.6, and the rubber thickness di is 2.0 m
m or more. LA1 = 0.65 · Kab --- (1) LA2 = 0.30 · Kab --- (2) LB1 = 0.65 · Kab --- (3) LB2 = 0.30 · Kab --- ( 4) In the formula, Kab is the following from the height H in the radial direction between the upper intersection A and the lower intersection B, and the length W from the heel point radius line M at the intermediate height point e to the tire cavity surface: (5)
Calculate by formula. Kab = {(H ² + 4W ² ) / 4W} · SIN ⁻¹ {4H · W / (H ² + 4W ² )} −−− (5)

Further, in the invention of claim 2, the protective rubber layer is characterized in that a loss coefficient tan δ is 0.035 to 0.18 at least in a region between the points A1 and B2.

In the invention of claim 3, the protective rubber layer is characterized in that at least the upper region EA has a complex elastic modulus E * of 7.0 to 13.0 Mpa.

According to a fourth aspect of the present invention, the protective rubber layer has a complex elastic modulus E * of 7.0 to 13.0 Mpa at least in the lower region EB.

According to a fifth aspect of the present invention, the protective rubber layer has a JISA rubber hardness HS of 60 to 80 degrees at least in a region between the point A2 and the lower intersection B.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a meridional section of the assembly of the pneumatic tire 1 and the rim 10 in a measured internal pressure filled state mounted on the rim and filled with a standard measured internal pressure. The “standard measurement internal pressure” is an air pressure determined for each tire in a standard system including a standard on which the tire is based.
RA "TIRE LOAD LIMITS AT VARIOUS COLD I
The maximum value described in "NFLATION PRESSURES" is "INFLATION PRESSURE" for ETRTO, and 180 KPa for passenger car tires.

In the figure, a pneumatic tire 1 (hereinafter referred to as tire 1) has a tire size of, for example, 215 in this example.
/ 45ZR16, a radial tire for a passenger car, which is located at a tread portion 2, a pair of sidewall portions 3 extending inward in the tire radial direction from both ends of the tread portion 2, and an inner end of each sidewall portion 3. And a bead portion 4.

The rim 10 is a 5 ° deep rim for a passenger car in this example, which is determined by a standard such as JATMA. The rim 10 has a rim seat surface 10A for receiving the bottom surface of the bead portion 4 and an outer surface of the bead portion 4. And a receiving flange surface 10B. The rim width of the rim 10 is defined as the distance between the heel point radius lines M extending radially through the bead heel point 11 where the rim sheet surface 10A and the flange surface 10B intersect.

A carcass 6 is bridged between the bead portions 4 and 4 on the tire 1, and a strong belt layer 7 is provided outside the carcass 6 and inside the tread portion 2, and inside the carcass 6. Is provided with an inner liner 12 for keeping the filling internal pressure airtight.

At least one carcass 6 is folded back from the inside in the tire axial direction to the outside in the tire axial direction around the bead core 5 of the bead portion 4 from the tread portion 2 to the side wall portion 3 and, in this example, one carcass 6 Formed from plies. This carcass ply is 75
It has carcass cords arranged at an angle of up to 90 degrees, and as the carcass cords, organic fiber cords such as nylon, rayon and polyester can be suitably used.

A space between the ply body 6A of the carcass 6 and the folded portions 6B on both sides thereof is filled with a bead apex rubber 8 rising from the bead core 5 outward in the tire radial direction to increase the tire lateral rigidity. I have.

The belt layer 7 is composed of one or more belt plies 7a and 7b for passenger car tires. The belt layer 7 reinforces almost the entire width of the tread portion 2 with a hammer effect. Has a low flatness of about 45% and restrains the tire. Each of the belt plies 7a and 7b has a belt cord arranged at an angle of 0 to 30 degrees with respect to the tire circumferential direction, and a high elastic material such as a steel cord or an aromatic polyamide cord is used for the belt cord. .

The inner liner 12 is a rubber layer mainly composed of butyl rubber such as butyl rubber or halogenated butyl rubber and having excellent gas impermeability.
The bead cores 5, 5 having a substantially uniform thickness of about 0 mm, usually 1.0 to 1.5 mm, are arranged along the inner surface of the ply body 6A.

Next, in the tire 1 according to the present invention, as shown in FIG. 4, the inner liner 12 is formed so as to intensively reinforce the contact portions J where the tire inner surfaces S contact each other during run flat. A thin protective rubber layer 13 is provided on the inner surface, and thereby a rubber thickness under the carcass 6 in a predetermined area including the contact portion J is secured in a predetermined range.

More specifically, when the tire is filled with the measured internal pressure, the heel point radius line M corresponds to the tire cavity surface S.
When the point on the tread side that intersects with the upper intersection A and the point on the bead side is the lower intersection B, the rubber thickness dA up to the carcass 6 at the upper intersection A is 2.0 mm or more, and this rubber thickness dA The ratio dA / DA to the tire thickness DA up to the tire outer surface at the upper intersection A is 0.2 to 0.6.
Up to the range.

Similarly, the carcass 6 at the lower intersection B
And the ratio dB / DB of the rubber thickness dB to the tire thickness DB to the tire outer surface at the lower intersection B is increased to a range of 0.2 to 0.6. ing.

Further, in the tire 1, when a point at which a tire axial direction line passing through an intermediate height point e between the upper intersection A and the lower intersection B intersects the tire lumen surface S is defined as a middle intersection C,
The rubber thickness dC up to the carcass 6 at this middle intersection C
Is not less than 3.0 mm, and the ratio d between the rubber thickness dC and the tire thickness DC to the tire outer surface at the middle intersection C is d.
C / DC is increased to the range of 0.4 to 0.6.

Here, the upper and lower intersections A and B are reference positions of the contact portion J, and at the time of run flat,
Further, rubbing occurs around the lower intersections A and B, and the carcass 6 is broken and damaged. Therefore, by increasing at least the rubber thicknesses dA and dB and the ratios dA / DA and dB / DB to the above ranges, it is possible to increase the traveling distance until the carcass 6 is exposed and directly rubbed, It improves run flatness.

The middle intersection C is located substantially at the center of the bend where the sidewall portion 3 is bent during run flat. Therefore, by increasing the rubber thickness dC and the ratio dC / DC to the above ranges, it is difficult to support the entire tire load at the time of puncturing as in a conventional run-flat tire, but the bending compression resistance is reduced. Thus, it is sufficiently possible to reduce the contact pressure at the contact portion J.
As a result, the run-flat performance can be further improved by a synergistic effect with the increase in the rubber thickness dA, dB at the contact portion J.

Although the protective rubber layer 13 is relatively thin, usually about 1.0 to 4 mm, depending on the thickness of the inner liner 12, the protective rubber layer 13 does not excessively increase tire weight and longitudinal rigidity. In addition, it is possible to maintain various performances such as riding comfort and rolling resistance in general running, and to make the driver aware of air deflation during a puncture.

When the rubber thicknesses dA, dB, and dC are less than 2.0 mm, 2.0 mm, and 3.0 mm, respectively, and the ratios dA / DA, dB / DB, and dC / DC are each 0.1 mm.
When it is less than 2, 0.2, or 0.3, the protective effect of protecting the carcass 6 from friction and heat generation is not sufficiently exhibited, and the required run flat performance cannot be secured. Conversely, the ratio dA / D
When each of A, dB / DB and dC / DC exceeds 0.6, the tire weight and the rolling resistance are increased as compared with general tires (non-run-flat tires), which results in impairing various running performances. Invite. Therefore, preferably, the ratio dA /
DA, dB / DB, and dC / DC are each 0.35 to
It is preferable to be in the range of 0.50, 0.25 to 0.50, 0.40 to 0.55.

On the other hand, the contact position of the contact portion J is determined by the influence of the lateral force during traveling and the like, and the upper region EA centering on the upper intersection A and the lower region EB centering on the lower intersection B are determined. With roses. Therefore, in order to ensure the effect of improving the run flat performance, as shown in FIG. 2, at any position i in both the upper region EA and the lower region EB, the rubber from this position i to the carcass 6 The thickness di is 2.0 mm or more, and the ratio d between the rubber thickness dB and the tire thickness Di from the position i to the outer surface of the tire.
It is necessary to increase i / Di to the range of 0.2 to 0.6.

Here, the upper area EA is defined as a point A1 separated from the tread side along the tire inner surface S with the distance LA1 represented by the following formula (1) and a bead side ( 2) means an area between the point A2 and the point A2 away from the distance LA2. Further, the lower region EB is a point B1 separated from a distance LB1 represented by the following formula (3) on the tread side along the tire lumen surface S around the lower intersection B and a distance represented by the formula (4) on the bead side. It means an area between the point B2 and the point B2 leaving the LB2.

The expressions (1) to (4) are as follows. LA1 = 0.65 · Kab --- (1) LA2 = 0.30 · Kab --- (2) LB1 = 0.65 · Kab --- (3) LB2 = 0.30 · Kab --- ( 4) Kab in the formula is the height H in the radial direction between the upper intersection A and the lower intersection B, and the length from the heel point radius line M at the intermediate height point e to the tire cavity surface S. It is obtained from the following equation (5) using the following equation (5). Kab = {(H ² + 4W ² ) / 4W} · SIN ⁻¹ {4H · W / (H ² + 4W ² )} −−− (5)

As shown schematically in FIG. 3, the Kab is used to move the tire cavity surface S between the upper and lower intersections A and B to the upper and lower intersections A and B.
It corresponds to the distance between the upper and lower intersections A and B along the tire lumen surface S when approximated as a single arc S0 passing through the three points of the middle and lower intersections A, C and B.

As described above, at each position i of the upper region EA and the lower region EB, the ratio di / Di is set to 0.2.
Since it is set to 0 to 0.60, the entire area that may actually contact during run flat can be protected by the protective rubber layer 13, and the effect of improving run flat performance can be ensured.

The main purpose of the protective rubber layer 13 is to secure the rubber thicknesses dA, dB, dC, and di. Therefore, the protective rubber layer 13 can be formed of rubber of the same quality as the inner liner 12 or carcass topping rubber. . However, from the viewpoint of a protective effect, the protective rubber layer 13 has a loss coefficient tanδ at least in a region between the points A1 and B2.
Is preferably formed of a low heat generation rubber of 0.035 to 0.18. As a result, deterioration of the protective rubber layer 13 itself due to heat generation at the contact portion J or the inner liner 1
2 and carcass 6 can be prevented from deteriorating, and the protection effect can be improved. If the loss coefficient tan δ is less than 0.035, the reinforcing property is poor. On the other hand, if it exceeds 0.18, heat tends to be generated, and thermal deterioration of the rubber cannot be suppressed. Therefore, the loss factor tan δ
Is more preferably 0.05 or more and 0.15 or less.

The protective rubber layer 13 is preferably a rubber having excellent mechanical strength such as cut resistance and wear resistance.
Therefore, in at least one of the upper region EA and the lower region EB, the complex elastic modulus E * is set to 7.
It is good to be 0-13.0 Mpa. Since the complex elastic modulus of the inner liner 12 is usually about 3.5 MPa and the complex elastic modulus of the carcass topping rubber is about 4.2 MPa, the mechanical strength is increased and the protective effect is increased by setting the above range. It can be understood that is obtained. If it is less than 7.0 Mpa, the reinforcing property of rubber is small, and 13.
If it exceeds 0 Mpa, the strain increases and the rolling resistance deteriorates. Here, the loss coefficient tan δ and the complex elastic modulus E * are values measured using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho under the conditions of a temperature of 70 ° C., a frequency of 10 Hz and a dynamic strain rate of 2%.

On the other hand, in a region where the dynamic shape change of the carcass 6 is large, it is preferable to suppress the dynamic change and reduce the contact pressure of the contact portion. Therefore, at least in a region between the point A2 and the lower intersection B,
JISA rubber hardness HS is set to 60 to 80 degrees. If the rubber hardness HS is less than 60 degrees, the reinforcing property is insufficient, and if it exceeds 80 degrees, the riding comfort deteriorates.

As described above, when a rubber having low heat generation and abrasion resistance is used for the contact portion, and a rubber having low heat generation and high hardness for suppressing movement is used in a portion where the dynamic fluctuation of the carcass 6 is large, The run-flat performance is further improved.

[0040]

EXAMPLE A tire having the structure shown in FIG. 1 was prototyped based on the specifications shown in Tables 1 and 2, and the tire weight, rolling resistance performance and run flat performance of each test tire were compared.

In the table, Conventional Example 1 is a conventional run-flat tire in which a high-hardness thick rubber reinforcing layer is provided on the inner surface of the sidewall portion to reduce longitudinal deflection, and Conventional Example 2 is a non-run-flat tire. It is a general tire.

Tire weight: The weight per test tire is measured and is indicated by an index with Conventional Example 1 being 100. The smaller the index, the better. -Rolling resistance performance: Using a rolling resistance tester, each test tire is mounted on a commercially available rim determined by the JATMA standard, and the speed (80 km / h) at a normal load determined by the JATMA standard at an internal pressure (197 kPa). And the rolling resistance is measured, and is indicated by an index with Conventional Example 1 being 100. The smaller the index, the better. -Run flat performance: Passenger cars (FR cars) with the test tires assembled to the applicable rims at rim pressure of 0 kPa
When traveling straight (50km / h) and turning (40km)
/ H) is run on the test course, and the running distance (km) until the tire is broken is indicated by an index with the conventional example 1 being 100. The larger the index, the better.

[0043]

[Table 1]

[0044]

[Table 2]

As shown in Tables 1 and 2, the tires of the examples have a running weight while maintaining various performances such as a tire weight and a rolling resistance performance which are substantially the same as those of a non-run-flat general tire (conventional example 2). It was confirmed that the flat performance could be greatly improved.

[0046]

The tire and rim assembly according to the present invention is constructed as described above, and the portion that contacts the inner surface of the tire during run flat is intensively strengthened. Can be recognized by tire deformation, and the use of general rims is possible, and tire weight, rolling resistance,
Run flat performance can be improved without impairing various performances such as rim detachability.

[Brief description of the drawings]

FIG. 1 is a sectional view of a tire and rim assembly according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating the upper region and the upper region.

FIG. 3 is a diagram illustrating a coefficient Kab used in equations (1) to (5).

FIG. 4 is a cross-sectional view showing a deformed state of the tire at an internal pressure of 0.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 10 Rim 10A Rim seat surface 10B Flange surface 11 Bead heel point 12 Inner liner 13 Protective rubber layer S Tire inner cavity surface

Claims (5)

[Claims] 1. A tire and rim assembly comprising a pneumatic tire and a rim seated on the bead portion, wherein the pneumatic tire is connected to a bead core of a bead portion from a tread portion to a sidewall portion. A carcass, an inner liner disposed along the inner surface of the carcass, and a protective rubber layer disposed along the inner surface of the inner liner to form a tire inner surface, and filled with a standard measurement internal pressure. In the tire meridian section in the measurement internal pressure filling state, an upper intersection point A where a heel point radius line M extending in a radial direction through a bead heel point where a rim seat surface and a flange surface of the rim intersect with each other and intersects a tire cavity surface on a tread portion side
The ratio dA / DA of the rubber thickness dA to the carcass to the tire thickness DA to the tire outer surface at 0.2 to 0.6, the rubber thickness dA is 2.0 mm or more, and the heel point radius line Lower intersection B where M intersects the tire lumen surface on the bead part side
The ratio dB / DB between the rubber thickness dB to the carcass and the tire thickness DB to the tire outer surface at 0.2 to 0.6, and the rubber thickness dB is 2.0 mm or more; and the upper intersection A Height point e between the road and the lower intersection B
The ratio dC / DC between the rubber thickness dC to the carcass and the tire thickness DC to the tire outer surface at a middle intersection C where the tire axial line passing through the tire inner surface intersects the tire lumen surface is 0.4 to 0.6;
In addition, the rubber thickness dC is equal to or more than 3.0 mm, and the point A is separated from the tread portion side along the tire lumen surface by a distance LA1 represented by the following equation (1) with the upper intersection A as a center.
1 and an upper area EA between a point A2 separated from the bead part by a distance LA2 expressed by the formula (2) and the following intersection (3) on the tread part side along the tire lumen surface around the lower intersection B. The rubber thickness di to the carcass at each position i in the lower region EB between the point B1 away from the distance LB1 represented by the formula and the point B2 away from the distance LB2 represented by the formula (4) on the bead portion side, and the tire outer surface. Up to the tire thickness Di
/ Di is 0.2 to 0.6, and the rubber thickness di is 2.
An assembly of a tire and a rim, which is set to 0 mm or more. LA1 = 0.65 · Kab --- (1) LA2 = 0.30 · Kab --- (2) LB1 = 0.65 · Kab --- (3) LB2 = 0.30 · Kab --- ( 4) In the formula, Kab is the following from the height H in the radial direction between the upper intersection A and the lower intersection B, and the length W from the heel point radius line M at the intermediate height point e to the tire cavity surface: (5)
Calculate by formula. Kab = {(H ² + 4W ² ) / 4W} · SIN ⁻¹ {4H · W / (H ² + 4W ² )} −−− (5) 2. The method according to claim 1, wherein the protective rubber layer has at least the point A1.
The loss coefficient tan δ is in a range between 0.035 and 0.18 in a region between the point B2 and the point B2.
A tire and rim assembly as described. 3. The protective rubber layer has a complex elastic modulus E * of at least 7.0 to 13.0 M in at least the upper region EA.
The tire and rim assembly according to claim 1, wherein the tire and the rim are pa. 4. The protective rubber layer has a complex elastic modulus E * of 7.0 to 13.0 M at least in the lower region EB.
The tire and rim assembly according to claim 1, wherein the tire and the rim are pa. 5. The protective rubber layer according to claim 1, wherein at least the point A2
And in a region between the lower intersection B and the JISA rubber hardness HS is 60 to 80 degrees,
5. The tire and rim assembly according to 2, 3, or 4.