JP2544559B2 - Radial tire and rim assembly - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radial tire capable of relieving push-up to a vehicle when riding over a protrusion.

[0002]

2. Description of the Related Art As the road network is improved and the performance of vehicles is improved, tires are required to have high steering stability and high-speed driving performance. In recent years, a strong belt layer has been used on the outside of a radial array carcass. Tightened flat radial tires are often used.

By flattening the tire, the tire lateral rigidity as well as the tread in-plane rigidity can be greatly increased, the straight running performance and the turning performance can be improved, and the rolling resistance can be reduced and the ground contact width can be expanded. It depends.

However, in particular, in a radial tire having an aspect ratio of 60% or less, the running performance is improved, but on the other hand, the reduction in the tire cross-section height due to the flatness causes the inner surface of the tread and the rim sheet to come close to each other.

As a result, when an excessive load f impacts the tread surface, for example, when a large protrusion on the road is passed over, the tire t is largely deflected, and the tread portion a as shown in FIG. The so-called rim touch in which the swelling adheres to the bead portion b is likely to occur. This rim touch is
Since the load is directly transmitted to the rim c, a large push-up force acts on the vehicle, and as a result, the durability of the vehicle is significantly impaired, resulting in serious adverse effects.

Therefore, in order to suppress the occurrence of such a rim touch, conventionally, for example, the carcass case is strengthened, or the gauge thickness from the bead portion to the sidewall portion is increased to increase the vertical spring constant of the tire. Deformation is being reduced.

[0007]

However, such reinforcing means by increasing the volume not only lowers the riding comfort, but also reduces the flexing margin leading to a rim touch, thereby achieving a sufficiently satisfactory effect. It's hard to do.

A part of a double structure type in which an inner tire is further provided in the tire inner cavity has been proposed, but this structure causes a large increase in tire weight and impairs fuel efficiency. In addition, durability will be reduced.

Therefore, in view of such a situation, the present inventor has considered
Sincere research has been conducted on the suppression of rim touch.

As a result, as shown in the relationship between the tire deflection amount K and the load f in FIG. 9, the tire increases the deflection amount K as the load f increases, and the deflection amount reaches KO, causing a rim touch. Up to the load-deflection curve and the area surrounded by the x-axis (shown by diagonal lines), the load energy S is accumulated in the tire. Therefore, the greater the load energy S leading up to the rim touch, the more the impact force can be absorbed, and the more effective suppression of the occurrence of the rim touch and the alleviation of the thrust force to the vehicle when the rim touch occurs. . It has been found that, for that purpose, it is necessary to increase the deflection amount KO up to the rim touch and to improve the proof stress against the load f.

That is, according to the present invention, by specifying both the cross-sectional shape and the rim shape of the tire skin, it is possible to increase the load energy leading to the rim touch without impairing the durability, riding comfort, steering stability and the like. An object of the present invention is to provide a radial tire and rim assembly that can solve the above problems.

[0012]

In order to achieve the above object, a radial tire-rim assembly according to the present invention is a radial tire-rim assembly having a bead portion seated on the rim. Includes a flange surface that receives the outer surface of the bead portion and has an upper end portion that has a radius of curvature R and is curved outward in the tire axial direction at the tire axial outer end of the rim seat surface that receives the bottom surface of the bead portion, The flange surface upper end height G from the bead heel point PO at which the rim seat surface and the flange surface intersect is not less than 0.67 times and not more than 0.84 times the flange surface upper end height GO in the standard rim, and the radius of curvature of the flange surface is A tire in a normal internal pressure state in which R is 1.1 times or more and 2.3 times or less of the radius of curvature RO of the flange surface in the standard rim, while the tire is filled with a normal value of internal pressure. In meridional section, the bead inner surface point P at the bead inner surface point P1 of the reference line X of the tire radial direction passing through the bead heal point PO intersects the inner surface of the bead portion
Ratio F / h of the distance h in the tire radial direction from the upper end of the flange surface to the tire equator point C where the outer surface of the tread portion intersects the tire equatorial plane, with respect to the bead thickness F which is the thickness of the bead portion in the normal direction of 1. An assembly of a radial tire and a rim with a value of 0.092 or less.

[0013]

In the radial tire and rim assembly of the present invention thus configured, the ratio of the distance h in the tire radial direction from the upper end of the flange to the tire equator point C to the bead thickness F at the bead inner surface point P1. F / h is smaller than that of conventional tires.
It is set to 092 or less. For conventional tires, the ratio F
/ H is about 0.110 or more.
By reducing the ratio F / h in this way, it becomes possible to increase the bending margin of the tire leading to the rim touch.

Further, the height G of the flange surface is higher than that of the standard rim.
And increasing the radius of curvature of the flange surface help to move the bead inner surface point P1 downward, respectively, and reduce the proportion of the non-deflected portion in the tire cross-section height to further increase the flexure allowance. sell.

The radius of curvature r of the arc L is 0.
When it is 77 times or more and is higher than that of the conventional tire, the degree of curvature of the sidewall portion is reduced and the amount of protrusion of the sidewall portion outward from the reference line X in the axial direction of the tire is reduced. As a result, in the lower region portion on the lower side of the tire maximum width position, the component force of the tire radial component of the axial force of the lower region portion increases, increasing the gauge thickness of the tire skin, that is, the bending margin. The vertical spring constant of the tire can be effectively increased without causing a decrease. As a result of these synergistic effects, the load energy of the tire can be greatly improved, as shown by the alternate long and short dash line in FIG. 9, without compromising durability, riding comfort, steering stability, etc. It can enhance sex.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a meridional section of a tire-rim assembly in a normal internal pressure state in which the rim 10 is mounted and filled with a normal value of internal pressure.

In the figure, a radial tire 1 includes a tread portion 2, sidewall portions 3 extending inward in the tire radial direction from both ends thereof, a tire radial inner end of each sidewall portion 3 and reinforcement by a bead core 5. And the bead portion 4 formed.

A tread portion 2 is provided between the bead portions 4 and 4.
The carcass 6 is folded around the bead core 5 from the inside of the tire to the outside through the sidewall part 3 and the belt layer 9 is provided outside the carcass 6 in the tire radial direction and inside the tread part 2. It is wound in the circumferential direction.

In this example, the carcass 6 includes two carcass plies 6a, an inner and an outer carcass ply, in which carcass cords are arranged at an angle of 75 degrees or more and 90 degrees or less with respect to the tire equatorial plane CO.
6b, the folded end of the inner carcass ply 6a covers the folded end of the outer carcass ply 6b and is interrupted near the tire maximum width position. Also, the main body portion 6A of the carcass 6
A hard bead apex rubber 8 that extends in a tapered shape from the bead core 5 toward the outer side in the tire radial direction is arranged between the and the folded portion 6B.

As the carcass cord, an organic fiber cord such as nylon, polyester or rayon is preferably used, and the carcass cords are arranged so that the plies cross each other. A metal fiber cord such as steel may be used as the carcass cord depending on the required tire performance.

The belt layer 9 is composed of two inner and outer belt plies 9a and 9b, and the ply width of the inner belt ply 9a in the tire axial direction is set to be larger than that of the outer belt ply 9b.

Further, the belt layer 9 has a maximum ply width, that is, a belt width which is the ply width of the inner belt ply 9a in this example, is 0.8 times or more the tread width TW, whereby almost the tread portion 2 is formed. The entire width is reinforced by the hoop effect, and in this example, the tire is restrained with a high flatness ratio of 60% or less. The flatness is represented by the ratio Ho / W of the tire cross-section height Ho to the tire width W.

The belt plies 9a and 9b have belt cords arranged at an angle of 0 to 30 degrees with respect to the tire equatorial plane CO. The belt cords include steel cords and aromatic polyamide cords. Highly elastic material is used.

As shown in FIG. 2, the rim 10 includes a rim sheet 10A for receiving the bottom surface of the bead portion 4, a rim sheet 10A for receiving an outer surface of the bead portion 4 and a tire radius from an outer end in the tire axial direction of the rim sheet 10A. In this example, it is a 5 ° deep-bottom rim for passenger cars, which has a flange 10B extending outward in the direction.

The flange 10B is a standing piece 10B extending outward in the tire radial direction at a substantially right angle to the tire shaft.
A curved portion 10B2 having a radius of curvature R and curving outward in the tire axial direction is provided at the upper end of 1.

The radius of curvature R of the flange surface 10BS, which is the inner surface of the flange 10B, is 1.1 times or more the radius of curvature RO of the standard rim Z (shown by the alternate long and short dash line) and 2.3.
On the other hand, the height G of the flange surface from the bead heel PO at which the rim sheet surface 10AS, which is the upper surface of the rim sheet 10A, and the flange surface 10BS intersect is set to double or less.
Is 0.67 times or more and 0.84 times or less of the flange surface upper end height GO of the standard rim Z.

As described above, with respect to the standard rim Z, the radius of curvature R is increased and the flange surface upper end height G is increased.
To decrease the position of the bead inner surface point P1 to be described below (inward in the tire radial direction), reduce the proportion of the non-deflected portion in the tire cross-section height H, and increase the flexure allowance. You can.

For example, in the standard rim Z having a rim size of 14 × 6JJ, the radius of curvature RO is 9 mm and the height GO of the flange surface is 18 mm. Therefore, in the present invention, the radius of curvature R is
Is 9.9 mm to 20.7 mm, and the flange upper end height G is 12.
It is set to 1 mm to 15.1 mm.

Further, in the present invention, the sectional shape of the tire outer cover in the state of the normal internal pressure is further specified.

That is, as shown in FIG.
When a vertical reference line X passing through the bead heel point PO in the tire radial direction is provided, the bead inner surface point P1 at the bead inner surface point P1 where the reference line X intersects with the inner surface of the bead portion 4 is provided.
A bead thickness F which is the thickness of the bead portion 4 in the normal direction of
The ratio F / h to the distance h in the tire radial direction from the upper end of the flange 10B to the tire equator point C is 0.092 or less. Moreover, in this example, at the tread inner surface point P2 where the reference line X intersects with the inner surface of the tread portion 2, the tread thickness H which is the thickness of the tread portion 2 in the normal direction of the tread inner surface point P2 and the bead thickness F. The ratio (F + H) / h of the above-mentioned distance h to the thickness F + H of the sum of and is 0.21 or less. The tire equator point C is a point on the tire equator line where the outer surface of the tread portion 2 intersects with the tire equatorial plane CO.

Here, in the tire 1, as schematically shown in FIG. 3, when the tread portion 2 is subjected to an impact load f, both the bead portion 4 and the side wall portion 3 are deformed and the flange 1
When the inner surface point P2 of the tread collides with the inner surface point P1 of the bead on 0B, a rim touch occurs. Therefore, the distance h which is the height of the tire from the upper end of the flange 10B.
Of the bead thickness F, that is, the ratio F / h is set to 0.092 or less, which is smaller than the conventional value, so that the distance h
It is possible to increase the amount of deflection in tires having the same.

On the other hand, the decrease of the height G of the upper end of the flange surface of the rim 10 and the increase of the radius of curvature R of the flange surface can reduce the height position of the bead inner surface point P1, respectively, as described above.
It is possible to reduce the proportion of the non-deflected portion in the tire cross-section height and increase the amount of deflection of the tire of the same size as in the non-F / h regulation.

As shown in FIG. 4, which shows the relationship between the flange surface upper end height G and the curvature radius R and the load energy, the load energy can be increased by decreasing the flange surface upper end height G and increasing the curvature radius R. It turns out that the rim touch can be suppressed.

Further, in FIG. 5, one tire of 185 / 60R14 is shown.
The above ratio F / h when mounted on a standard rim Z of 4 × 6JJ
And the load energy are shown, and the load energy of the tire with the ratio F / h of 0.092 or less is 51.
It can be seen that the load energy of the conventional tire is extremely low at 44.3 kgfm or less compared to 6 kgfm or more.

However, even when the ratio F / h is reduced, when the tread thickness H increases, the increase of the load energy cannot be expected sufficiently. Therefore, in this example, the effect of the ratio F / h is obtained. Ratio (F + H)
/ H is 0.21 or less. In the conventional tire, the ratio (F + H) / h is about 0.24 or more.

Further, in this example, the midpoint Q1 of the bead thickness F and the midpoint Q2 of the tread thickness H are further added.
And the ratio r / h of the distance h to the radius of curvature r of the arc L passing through the thickness midpoint Q3 of the thickness of the sidewall portion 3 at the tire maximum width position M is 0.77 or more.

By setting the ratio r / h to be 0.77 or more, the degree of curvature of the sidewall portion 3 can be reduced and the amount of the sidewall portion 3 overhanging from the reference line X can be reduced. As a result, as shown in FIG. 7, the component force gx of the tire radial component of the axial force g of the lower region portion ML located below the tire maximum width position M is increased, and the vertical spring of the tire is increased. The constant can be increased and the proof stress against the impact load f can be improved.

The ratio r / h when the 185 / 60R14 tire is mounted on the standard rim Z of 14 × 6JJ in FIG.
The relationship between the load energy and the load energy is shown, and the longitudinal spring constant index increases in the tire with the ratio r / h of 0.77 or more,
In the conventional tire, the load energy is 45 kgfm, whereas in the present embodiment, a high load energy of 50 kgfm or more can be obtained.

As described above, since the improvement of the yield strength and the increase of the deflection amount can be independently achieved by specifying the tire cross-sectional shape, the load energy which the tire can accumulate and absorb, as shown by the one-dot chain line in FIG. Therefore, the rim touch resistance and the effect of alleviating the thrust force to the vehicle when the rim touch occurs can be improved.

The ratio F / h and the ratio (F + H) / h
Are preferably 0.080 or more and 0.18 or more, respectively, and the ratio F / h and the ratio (F + H) / h are respectively 0.
When it is less than 080 and 0.18, the bead thickness F and the tread thickness H become too small, which makes it difficult to maintain the tire rigidity, impairing the tire durability and, conversely, inducing a rim touch.

The ratio r / h is preferably 0.79 or less. When the ratio r / h is larger than 0.79, the riding comfort is impaired, the tire lateral rigidity is reduced, and the steering stability is reduced. To do.

(Specific Example) The structure shown in FIG. 1 is used, the tire size is 185 / 60R14, and the rim size is 14 ×.
A 6 JJ tire and rim assembly was prototyped based on the specifications in Table 1, and the load energy leading to the rim touch of the tire, steering stability, riding comfort and rolling resistance were compared with the conventional product and the comparative example product.

[0043]

[Table 1]

The load energy is represented by an index with the value when the internal pressure of 2.0 kc is filled being 100 for the conventional tire. The rolling resistance is an index of rolling resistance when a load of 350 kg is applied to the tire and the tire is rolled at a constant speed of 80 km / h, with the conventional tire being 100, and the steering stability is also stable. And ride comfort are evaluated based on the driver's feeling when the vehicle actually travels.

[0045]

Since the radial tire and rim assembly of the present invention is constructed as described above, the rim touch resistance of the tire can be greatly improved without impairing riding comfort, steering stability and the like.

[Brief description of drawings]

FIG. 1 is a meridional sectional view of a tire-rim assembly showing an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing an enlarged part of a rim.

FIG. 3 is a schematic cross-sectional view showing a flexed state of a tire.

FIG. 4 is a diagram showing a relationship between a flange surface upper end height and a flange surface curvature radius and load energy.

FIG. 5 is a diagram showing a relationship between a ratio F / h and load energy.

FIG. 6 is a diagram showing a relationship between a ratio r / h and load energy.

FIG. 7 is a schematic diagram illustrating the action of the ratio r / h.

FIG. 8 is a schematic cross-sectional view of a tire illustrating a rim touch.

FIG. 9 is a diagram showing a tire load-deflection curve up to a rim touch.

[Explanation of symbols] 4 bead portion 10 rim 10AS rim seat surface 10BS flange surface Z standard rim

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-56-60701 (JP, A) JP-A-63-199102 (JP, A) JP-A-2-88304 (JP, A) JP-A-50- 12702 (JP, A) JP 54-40406 (JP, A) JP 59-48204 (JP, A) JP 58-161603 (JP, A) JP 64-9007 (JP, A) JP-A-1-309805 (JP, A) JP-A-60-8102 (JP, A) JP-A-3-79404 (JP, A) JP-A-1-114501 (JP, A) JP-A-63-154402 (JP, A) JP-A-1-202502 (JP, A) JP-A-57-47203 (JP, A) JP-A-2-306803 (JP, A)

Claims (2)

(57) [Claims] 1. A radial tire-rim assembly having a bead portion seated on a rim, wherein the rim receives an outer surface of the bead portion at an outer end in a tire axial direction of a rim seat surface that receives a bottom surface of the bead portion. In addition, the upper end portion has a flange surface that has a radius of curvature R and curves outward in the tire axial direction, and the flange surface upper end height G from the bead heel point PO where the rim seat surface and the flange surface intersect is the flange in the standard rim. The upper surface height GO is 0.67 times or more and 0.84 times or less, and the curvature radius R of the flange surface is 1.1 times or more and 2.3 times or less of the curvature radius RO of the flange surface in the standard rim. On the other hand, in the tire meridional section in the normal internal pressure state in which the tire is filled with the normal value of the internal pressure, the reference line X in the tire radial direction passing through the bead heel point PO is the bead portion. Bead inner surface point intersect the inner surface P1
In the radial direction of the tire from the upper end of the flange surface to the tire equatorial point C where the outer surface of the tread portion intersects the tire equatorial surface with respect to the bead thickness F which is the thickness of the bead portion in the normal direction of the bead inner surface point P1. An assembly of a radial tire and a rim in which the ratio F / h of h is 0.092 or less. 2. The thickness of the tread portion in the normal direction of the tread inner surface point P2 at the middle point Q1 of the bead thickness F and the tread inner surface point P2 where the reference line X intersects the inner surface of the tread portion. The middle point Q2 of the tread thickness H, which is
A radial tire / rim combination in which the ratio r / h of the distance h to the radius of curvature r of the arc L passing through the thickness midpoint Q3 of the thickness of the sidewall portion at the tire maximum width position is 0.77 or more. Three-dimensional.