JP2021054296A - Tire/rim assembly - Google Patents

Abstract

To provide a tire/rim assembly which can reduce air resistance.SOLUTION: A tire/rim assembly includes a rim having a flange Rb, and a pneumatic tire 1 mounted on the rim. The pneumatic tire 1 includes a rim guard 10 which projects to an outer side in a tire axial direction from a side wall reference external surface J so as to cover the flange Rb. An angle θ of a rim guard straight line 11, which connects an outer end 10a of the rim guard 10 in the tire axial direction and an outer end 10e of the rim guard 10 in a tire radial direction, with respect to the tire radial direction is 40 degrees or less. A distance a in the tire axial direction between the outer end Re of the flange Rb in the tire axial direction and the outer end 10a of the rim guard 10 in the tire axial direction is 10 mm or less.SELECTED DRAWING: Figure 2

Description

The present invention relates to a tire / rim assembly.

Patent Document 1 below describes a pneumatic tire mounted on a rim. The pneumatic tire mounted on the rim has a front side shape equal to the maximum tire width in the vicinity of the rim flange, and the side surface is formed by a curved line or a straight line in which the tire width decreases to the tread portion.

Japanese Unexamined Patent Publication No. 63-247104

In the pneumatic tire of Patent Document 1, there is room for improvement in reducing the air resistance of the tire and improving fuel efficiency (improving fuel efficiency).

The present invention has been devised in view of the above circumstances, and a main object of the present invention is to provide a tire / rim assembly capable of reducing air resistance.

The present invention is a tire / rim assembly including a rim having a pair of flanges and a pneumatic tire mounted on the rim, wherein the pneumatic tire has a pair of bead portions and the pair of beads. In a tire meridional cross section in a normal state with no load, which includes a carcass bridged between the portions and a rim guard provided on at least one of the pair of bead portions, and the tire / rim assembly is filled with a normal internal pressure. The rim guard protrudes outward in the tire axial direction so as to cover the flange from the sidewall reference outer surface, and the outer end of the rim guard in the tire axial direction and the outer end of the rim guard in the tire radial direction are formed. The angle θ of the connecting rim guard straight line with respect to the tire radial direction is 40 degrees or less, and the distance a in the tire axial direction between the outer end of the flange in the tire axial direction and the outer end of the rim guard in the tire axial direction is 10 mm or less. It is a tire / rim assembly.

The tire / rim assembly according to the present invention preferably has an angle θ of 35 degrees or less.

In the tire / rim assembly according to the present invention, it is desirable that the rim guard has a rim guard surface that matches the rim guard straight line.

In the tire / rim assembly according to the present invention, it is desirable that the rim guard has a concave arc-shaped rim guard surface inside the tire radial direction from the rim guard straight line.

In the tire / rim assembly according to the present invention, it is desirable that the radius of curvature of the concave arc-shaped rim guard surface is 100 to 300 mm.

In the tire / rim assembly according to the present invention, it is desirable that the distance a is 5 mm or less.

In the tire / rim assembly according to the present invention, it is desirable that the distance a is 1 to 2 mm.

In the tire / rim assembly according to the present invention, the carcass extends between the bead cores embedded in each of the pair of bead portions, and the main body portion is connected to the bead core from the inside in the tire axial direction. It is desirable that the outer end of the folded portion in the tire radial direction, including the folded portion folded outward, is located outside the tire radial direction of the outer end of the rim guard in the tire axial direction.

In the tire / rim assembly according to the present invention, it is desirable that the outer end of the folded portion in the tire radial direction is located inside the tire radial direction of the outer end of the rim guard in the tire radial direction.

In the tire / rim assembly according to the present invention, the apex rubber is arranged outside the bead core in the tire radial direction, and the outer end of the apex rubber in the tire radial direction is more tire than the outer end of the rim guard in the tire axial direction. It is desirable that it is located on the outside in the radial direction.

In the tire / rim assembly according to the present invention, the rubber gauge on the outer side of the carcass in the tire axial direction at the outer end position of the rim guard in the tire axial direction is the tire shaft of the carcass at the outer end position of the rim guard in the tire radial direction. It is desirable that it is 3 times or less of the rubber gauge on the outside of the direction.

By providing the above configuration, the tire / rim assembly of the present invention can reduce air resistance during traveling and improve fuel efficiency.

It is sectional drawing of the tire rim assembly of this invention. It is an enlarged view of the bead portion and the sidewall portion of FIG. It is the schematic sectional drawing of the tire rim assembly mounted on a vehicle. It is a front view of the vehicle of FIG. It is an enlarged view of the bead portion and the sidewall portion of FIG. It is an enlarged sectional view of the bead part of another actual form.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view of a tire meridian including a tire rotation axis (not shown) in a normal state of the tire / rim assembly (hereinafter, may be simply referred to as “assembly”) T of the present embodiment. As shown in FIG. 1, the assembly T of the present embodiment includes a rim R and a pneumatic tire (hereinafter, may be simply referred to as a “tire”) 1 mounted on the rim R. .. FIG. 1 shows, for example, a tire 1 for a passenger car. However, the present invention can also be applied to tires 1 for motorcycles, heavy loads, and the like.

The rim R of the present embodiment includes a pair of bases Ra that receive the bottom surface of the bead portion 4 of the tire 1, and a pair of flanges Rb that are connected to the outer end of the base Ra in the tire axial direction and extend outward in the tire radial direction. .. The flange Rb supports, for example, the outer surface of the bead portion 4. As the rim R, in this embodiment, the regular rim R1 defined by standards such as JATMA, TRA, and ETRTO is adopted.

The "normal state" is a state in which the tire 1 is rim-assembled on the normal rim R1, the normal internal pressure is applied, and there is no load. Unless otherwise specified in the present specification, the dimensions of each part of the assembly T are values measured in a normal state.

The "regular internal pressure" is the air pressure defined for each tire in the standard system including the standard on which the tire 1 is based. For JATMA, the "maximum air pressure", and for TRA, the table "TIRE LOAD". The maximum value described in "LIMITS AT VARIOUS COLD INFLATION PRESSURES", or "INFLATION PRESSURE" for ETRTO.

In the tire 1, for example, a tread portion 2 having a tread surface 2a in contact with the road surface, a sidewall portion 3 extending inward in the radial direction of the tire from both ends of the tread portion 2, and a bead core 5 connected to the sidewall portion 3 are embedded. The bead portion 4 is included.

The tire 1 of the present embodiment includes a carcass 6 bridged between the bead portions 4 and a belt layer 7 arranged outside the carcass 6 in the tire radial direction and inside the tread portion 2. Further, the tire 1 includes an apex rubber 8 made of hard rubber arranged on the outer side of the bead core 5 in the radial direction of the tire, and a sidewall rubber 3G forming the outer surface 3a of the sidewall portion 3. As the bead core 5, the belt layer 7, the apex rubber 8 and the sidewall rubber 3G, known embodiments are appropriately adopted.

In the present embodiment, the carcass 6 is formed of one carcass ply 6A. The carcass ply 6A is formed by, for example, covering a carcass cord arranged at an angle of 75 to 90 ° with respect to the tire equator C with a rubber material (not shown).

The carcass ply 6A includes, for example, a main body portion 6a and a folded-back portion 6b. The main body 6a extends, for example, between the bead cores 5 in a toroid shape. The folded-back portion 6b is connected to the main body portion 6a and is folded back around the bead core 5 from the inside to the outside in the tire axial direction, for example.

FIG. 2 is an enlarged view of the bead portion 4 and the sidewall portion 3 of FIG. As shown in FIG. 2, the tire 1 of the present embodiment further includes a rim guard 10 projecting outward in the tire axial direction so as to cover the flange Rb from the sidewall reference outer surface J. The rim guard 10 is provided on at least one of the bead portions 4, and in the present embodiment, on both bead portions 4. Further, the rim guard 10 of the present embodiment is continuous in the tire circumferential direction.

In the present specification, the sidewall reference outer surface J is formed by moving the outer contour line 6s of the carcass ply 6A on the reference point P along the tire axial direction. The reference point P is a point on the outer surface 1a of the tire 1 at the position of the inner end 5i of the bead core 5 in the radial direction of the tire. For the outer contour line 6s, the outer surface 12 of the folded-back portion 6b is adopted, and the outer surface 13 of the main body portion 6a is adopted in the region where the folded-back portion 6b is not provided (the region outside the folded-back portion 6b in the tire radial direction). Will be done.

FIG. 3 is a cross-sectional view of the vehicle S on which the assembly T is mounted, cut along a plane. FIG. 4 is a front view of the left half of the vehicle S on which the assembly T is mounted. As shown in FIGS. 3 and 4, on the outside of the vehicle of the assembly T, the vicinity of the bead portion 4 may be exposed to the outside of the vehicle S. Therefore, the angle θ with respect to the tire radial direction of the rim guard straight line 11 connecting the outer end 10a of the rim guard 10 in the tire axial direction and the outer end 10e of the rim guard 10 in the tire radial direction is set to 40 degrees or less. As a result, when the vehicle S travels, the air resistance of the air h flowing from the surface of the rim guard straight line 11 to the rim R side can be reduced. The reference numeral F indicates the traveling direction of the vehicle S. Further, when a plurality of outer ends 10a of the rim guard 10 in the tire axial direction are formed on the rim guard 10, the outer ends arranged on the outermost side in the tire radial direction are adopted. Further, when the outer contour line 6s of the carcass ply 6A is not connected to the outer surface 1a of the tire 1, the outer end 10e of the rim guard 10 adopts a position where the outer contour line 6s and the outer surface 1a are closest to each other.

As shown in FIG. 2, the distance a in the tire axial direction between the outer end Re of the flange Rb in the tire axial direction and the outer end 10a of the rim guard 10 in the tire axial direction is 10 mm or less. As a result, the resistance when the air passing through the surface of the rim guard straight line 11 flows to the rim R side is reduced. As described above, in the assembly T of the present embodiment, the resistance of the air flowing on the surface of the rim guard 10 can be reduced by the cooperation of the angle θ and the distance a.

The angle θ is preferably 35 degrees or less, and more preferably 30 degrees or less in order to effectively exert the above-mentioned action. If the angle θ becomes excessively small, the boundary layer of the air flowing on the surface of the rim guard 10 is likely to be peeled off, and the air resistance may be rather increased. Further, when the angle θ is excessively small, if the outer end 10e of the rim guard 10 in the tire radial direction is positioned relatively outside in the tire radial direction, the volume of the rim guard 10 may increase and the rolling resistance may deteriorate. .. Therefore, the angle θ is preferably 5 degrees or more, and preferably 10 degrees or more.

The distance a is preferably 5 mm or less. As a result, the separation of air between the flange Rb and the rim guard 10 is further suppressed. Further, in order to protect the flange Rb while reducing the air resistance, the distance a is more preferably 1 to 2 mm.

The maximum separation distance A in the tire radial direction between the flange Rb and the rim guard 10 is preferably 2.0 mm or less, and more preferably 1.5 mm or less. As a result, the flow of air between the flange Rb and the rim guard 10 is further suppressed. If the maximum separation distance A is excessively small, the rim guard 10 and the flange Rb may come into close contact with each other during traveling, and the rim guard 10 may be damaged, which may increase the air resistance. Therefore, the maximum separation distance A is preferably 1.0 mm or more.

FIG. 5 is a cross-sectional view of the sidewall portion 3 and the bead portion 4. As shown in FIG. 5, in the present embodiment, the rim guard surface 10s forming the outer surface 1a of the tire 1 is arranged inside the outer surface 14 and the outer surface 14 in the tire radial direction. It is formed including the side surface 15.

The outer side surface 14 is formed by connecting, for example, the outer end 10a of the rim guard 10 in the tire radial direction and the outer end 10e of the rim guard 10 in the tire axial direction, and is inclined outward in the tire axial direction toward the inside in the tire radial direction. doing. The outer surface 14 of the present embodiment is formed in a concave arc shape inward in the radial direction of the tire from the rim guard straight line 11. Such an outer surface 14 suppresses contact between the air h flowing from the outer surface 14 side to the rim R side and the rim R when the vehicle is traveling, and prevents the air on the surface of the rim R from peeling off. The reduction effect is enhanced to improve fuel efficiency.

The radius of curvature r of the outer side surface 14 is preferably 100 to 300 mm. If the radius of curvature r is less than 100 mm, a large stress concentration occurs on the outer surface 14, and the rim guard 10 may be damaged. When the radius of curvature r exceeds 300 mm, the contact between the air h flowing from the outer surface 14 side to the rim R side and the rim R may not be effectively suppressed when the vehicle is traveling. The radius of curvature r is an average value between the outer end 10a of the rim guard 10 in the tire radial direction and the outer end 10e of the rim guard 10 in the tire axial direction.

The inner side surface 15 is formed, for example, by connecting the outer end 10a of the rim guard 10 in the tire axial direction and the reference point P, and is inclined inward in the tire axial direction toward the inside in the tire radial direction. In the present embodiment, the inner side surface 15 has a small inclined portion 16 extending inward in the tire radial direction from the outer end 10a of the rim guard 10 in the tire axial direction, and a large inclined portion 16 extending inward in the tire radial direction connected to the small inclined portion 16. A portion 17 and a contact portion 18 connected to the large inclined portion 17 are included. The small inclined portion 16 has, for example, an inner end 16i that extends linearly and terminates outside the flange Rb in the tire axial direction. For example, the large inclined portion 17 extends outward in the radial direction of the tire in a concave arc shape and is inclined at a larger angle with respect to the tire axial direction than the small inclined portion 16. The large inclined portion 17 is separated from the rim R. The contact portion 18 is, for example, in contact with the rim R and smoothly connected to the large inclined portion 17 so as to extend inward in the tire axial direction in a concave arc shape.

As described above, the rim guard surface 10s of the present embodiment has a substantially trapezoidal shape having the reference point P, the inner end 16i, the outer end 10a of the rim guard 10 in the tire axial direction, and the outer end 10e of the rim guard 10 in the tire radial direction as vertices. It is formed. The rim guard surface 10s of the rim guard 10 is not limited to such an embodiment, and the reference point P, the outer end 10a of the rim guard 10 in the tire axial direction, and the outer end 10e of the rim guard 10 in the tire radial direction are the vertices. It may have a substantially triangular shape.

It is desirable that the outer end 10a of the rim guard 10 in the tire axial direction is located inside the outer end 6e of the folded-back portion 6b in the tire radial direction in the tire radial direction. As a result, the rigidity of the rim guard 10 is maintained high, so that the deformation of the rim guard 10 due to the load is suppressed, and the effect of reducing the air resistance is maintained high.

It is desirable that the outer end 10a of the rim guard 10 in the tire axial direction is located inside the outer end 8e of the apex rubber 8 in the tire radial direction in the tire radial direction. As a result, the rigidity maintaining effect of the above-mentioned rim guard 10 is highly exerted, and the air resistance reducing effect is exerted.

The rubber gauge of the sidewall rubber 3G is relatively small on the outer side of the rim guard 10 in the tire radial direction and outside the tire radial direction of the outer end 10e. As a result, for example, when the outer end 6e of the folded-back portion 6b in the tire radial direction is located outside the outer end 10e of the rim guard 10 in the tire radial direction, the outer end 10e of the rim guard 10 is located outside the tire radial direction. A large change in rigidity occurs in the radial direction of the tire. Therefore, in this portion, the deformation of the sidewall portion 3 due to the load becomes large, and the air resistance becomes large. From this point of view, it is desirable that the outer end 10e of the rim guard 10 in the tire radial direction is located outside the tire radial outer end 6e of the folded-back portion 6b in the tire radial direction. Similarly, it is desirable that the outer end 10e of the rim guard 10 in the tire radial direction be located outside the tire radial direction of the outer end 8e of the apex rubber 8 in the tire radial direction.

In the present embodiment, the outer end 6e of the folded-back portion 6b in the tire radial direction is from the intermediate position in the tire radial direction between the outer end 10a of the rim guard 10 in the tire axial direction and the outer end 10e of the rim guard 10 in the tire radial direction. Is also located outside the tire radial direction. In the present embodiment, the outer end 8e of the apex rubber 8 in the tire radial direction is located at an intermediate position in the tire radial direction between the outer end 10a of the rim guard 10 in the tire axial direction and the outer end 10e of the rim guard 10 in the tire radial direction. Is also located outside the tire radial direction.

The outer rubber gauge w1 of the carcass 6 in the tire axial direction at the outer end 10a position of the rim guard 10 in the tire axial direction is the outer rubber gauge w2 of the carcass 6 in the tire axial direction of the outer end 10e of the rim guard 10 in the tire radial direction. It is desirable that it is less than double. As a result, the effect of reducing air resistance is further exhibited. The rubber gauges w1 and w2 are the lengths of the sidewall rubber 3G in the tire axial direction in the present embodiment.

FIG. 6 is an enlarged view of the bead portion 4 of another embodiment. The same components as the components of the present embodiment are designated by the same reference numerals, and the description thereof will be omitted. As shown in FIG. 6, the outer surface 14 of the rim guard 10 of the bead portion 4 of this embodiment coincides with the rim guard straight line 11. In other words, the outer surface 14 is formed in a straight line. Such an outer surface 14 reduces air resistance, increases the rigidity of the rim guard 10 to suppress damage thereof, and maintains the effect of reducing air resistance for a long period of time.

Although the particularly preferable embodiments of the present invention have been described in detail above, the present invention is not limited to the illustrated embodiments, and can be modified into various embodiments.

A pneumatic tire for a passenger car of size 225 / 40R18 having the basic structure shown in FIG. 1 was prototyped based on the specifications shown in Table 1. Then, the fuel efficiency performance of each test tire was tested. The test method is as follows.

<Fuel efficiency performance>
Each test tire was mounted on all wheels of a 2000cc passenger car under the following conditions. Then, the test driver ran the test vehicle, and the fuel consumption (mileage per 1 L of fuel) was measured. The result is represented by an index with Comparative Example 1 as 100, and the larger the value, the smaller the air resistance and the better.
Mileage: 5000km
Rim: 18 x 6.0J
Internal pressure: 220 kPa

As a result of the test, it is understood that the test tire of the example has improved fuel efficiency as compared with the test tire of the comparative example.

1 Pneumatic tire 10 Rim guard 10a Outer end in tire axial direction 10e Outer end in tire radial direction 11 Rim guard straight line R Rim Rb Flange Re Flange outer end

Claims (11)

A tire / rim assembly comprising a rim having a pair of flanges and a pneumatic tire mounted on the rim.
The pneumatic tire includes a pair of bead portions, a carcass bridged between the pair of bead portions, and a rim guard provided on at least one of the pair of bead portions.
In the tire meridian cross section in the normal state of no load in which the tire / rim assembly is filled with the normal internal pressure.
The rim guard protrudes outward in the tire axial direction so as to cover the flange from the outside surface of the sidewall reference.
The angle θ of the rim guard straight line connecting the outer end of the rim guard in the tire axial direction and the outer end of the rim guard in the tire radial direction with respect to the tire radial direction is 40 degrees or less.
The distance a in the tire axial direction between the outer end of the flange in the tire axial direction and the outer end of the rim guard in the tire axial direction is 10 mm or less.
Tire / rim assembly. The tire / rim assembly according to claim 1, wherein the angle θ is 35 degrees or less. The tire / rim assembly according to claim 1 or 2, wherein the rim guard has a rim guard surface that matches the rim guard straight line. The tire / rim assembly according to claim 1 or 2, wherein the rim guard has a concave arc-shaped rim guard surface inside the tire radial direction from the rim guard straight line. The tire / rim assembly according to claim 4, wherein the radius of curvature of the concave arc-shaped rim guard surface is 100 to 300 mm. The tire / rim assembly according to any one of claims 1 to 5, wherein the distance a is 5 mm or less. The tire / rim assembly according to claim 6, wherein the distance a is 1 to 2 mm. The carcass includes a main body portion extending between the bead cores embedded in each of the pair of bead portions, and a folded portion connected to the main body portion and folded around the bead core from the inside to the outside in the tire axial direction. ,
The tire / rim assembly according to any one of claims 1 to 7, wherein the outer end of the folded portion in the tire radial direction is located outside the tire axial outer end of the rim guard in the tire radial direction. The tire / rim assembly according to claim 8, wherein the outer end of the folded portion in the tire radial direction is located inside the tire radial direction of the outer end of the rim guard in the tire radial direction. Apex rubber is arranged on the outside of the bead core in the radial direction of the tire.
The tire / rim assembly according to claim 8 or 9, wherein the outer end of the apex rubber in the tire radial direction is located outside the tire radial outer end of the rim guard in the tire axial direction. The outer rubber gauge of the carcass in the tire axial direction at the outer end position of the rim guard in the tire axial direction is three times or less the outer rubber gauge of the carcass in the tire axial direction at the outer end position of the rim guard in the tire radial direction. , The tire / rim assembly according to any one of claims 1 to 10.

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