JPH08258518A - Pneumatic tire provided with rim guard - Google Patents

Abstract

PURPOSE: To improve the heat radiating effect and fuel consumption by forming a meridian sectional form of an annular rib into a triangular or trapezoidal shape, making the length of an outer side in the radial direction longer than an inner side in the radial direction, and providing many uncontinuous recessed parts in the circumferential direction on the periphery of the annular rib. CONSTITUTION: A rim guard composed of an annular rib R in which rubber is erected outward in the tire axial direction is provided between the vicinity of the position M of the tire maximum width and the vicinity of a rim line L. The meridian sectional form of the annular rib R is approximately triangular, the maximum thickness W is 6.1mm, the length of a side 1 outward in the radial direction is 18.7mm, and the length of a side 2 inward in the radial direction is 13mm. Accordingly, the length of the side 1 outward in the radial direction is 1.43 times as long as the side 2. Forty five uncontinuous elliptical recessed parts D are provided at equal distances in the circumferential direction so that the continuity in the circumferential direction of the annular rib R may not deteriorated. Therefore, the surface area of the rim guard is increased, the heat radiating property is improved, and the weight of the tire is restrained from being increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire having a rim guard.

[0002]

2. Description of the Related Art Generally, in a flat pneumatic tire having an aspect ratio of 60 or less, which is the ratio of the tire cross-section maximum width to the tire cross-section maximum width, the rim flange exceeds the tire cross-section maximum width when the tire is assembled on the rim. The rim / flange tends to be damaged due to curb rubbing when the tire is running. Therefore, a pneumatic tire is proposed and put into practical use, which is provided with a rim guard composed of an annular rib in which rubber is bulged outward in the tire axial direction between the vicinity of the maximum tire width and the vicinity of the rim line.

[0003]

In recent years, a pneumatic tire equipped with a large rim guard has been developed in order to surely protect the rim flange from damage caused by rubbing of a curb during traveling of the tire, and also in terms of fashionability. Especially for flat pneumatic tires with an aspect ratio of 60 or less,
It is becoming mainstream. However, in a pneumatic tire with a large rim guard, heat dissipation from the tire bead part is hindered, the bead part heats up, bead part failure such as separation easily occurs, and the tire weight increases, There was a drawback that fuel consumption increased.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a tire having excellent heat dissipation effect of the tire / bead portion and good fuel efficiency.

[0005]

In order to achieve the above object, the pneumatic tire according to the present invention has an aspect ratio of 60 or less, which is a ratio of a tire height to a maximum tire width, in the vicinity of the maximum tire width. In a pneumatic tire having a rim guard made of an annular rib in which rubber bulges outwardly in the axial direction of the tire between and near the rim line, (1) the meridional cross-sectional shape of the annular rib is triangular or trapezoidal or nearly triangular or It is almost trapezoidal, and the length of the side on the outer side in the radial direction is larger than the length of the side on the inner side in the radial direction. It is a pneumatic tire.

To achieve the above object, in the pneumatic tire according to the present invention, the length of the radially outer side of the meridional section of the annular rib is 1.2 to 2 times the length of the radially inner side. Preferably there is.

In order to achieve the above object, in the pneumatic tire according to the present invention, the radially inner side of the meridional section of the annular rib has a much smaller radius of curvature than the radius forming the radially outer side. It is preferable that the outer side in the radial direction is formed in a substantially straight line.

In order to achieve the above object, in the pneumatic tire according to the present invention, the surface area of the circumferentially discontinuous recess is approximately equal to the value obtained by removing the surface area of the circumferentially discontinuous recess from the surface area of the annular rib. It is preferably the same.

In order to achieve the above object, in the pneumatic tire according to the present invention, the surface area of the circumferentially discontinuous concave portion is the circumferential direction of the annular rib before the circumferentially discontinuous concave portion is provided. It is preferably 110 to 150% of the surface area of the portion corresponding to the discontinuous concave portion.

In order to achieve the above object, in the pneumatic tire according to the present invention, a large number of circumferentially discontinuous recesses are provided on the circumference of the annular rib so as not to impair the circumferential continuity of the annular rib. It is preferable.

In order to achieve the above object, in the pneumatic tire according to the present invention, it is preferable that the circumferentially discontinuous recess provided on the circumference of the annular rib is circular or elliptical.

[0012]

The function of the pneumatic tire according to the present invention is
A rim guard consisting of an annular rib with a ratio of 60 or less and rubber bulging outward in the axial direction of the tire is provided between the vicinity of the maximum tire width and the vicinity of the rim line, and the annular rib has a triangular or trapezoidal cross section. Alternatively, the tire has a substantially triangular shape or a substantially trapezoidal shape, and the length of the outer side in the radial direction is larger than the length of the inner side in the radial direction, and a large number of circumferentially discontinuous recesses are provided on the circumference of the annular rib. There is. "Aspect ratio" is the ratio of the tire meridian section height to the tire meridian section maximum width,
“Tire maximum width” refers to the maximum tire width measured without the letters, white lines or protectors for side cut prevention and the rim guard for protecting the rim flange provided on the side. The "rim line" is a small ridge that is located radially outside the rim flange when the tire is assembled to the rim and is annularly provided on the bead surface of the tire. The tire and the rim are concentric circles. It is for checking whether or not it is assembled in a state. The pneumatic tire according to the present invention, as described above,
Since many circumferentially discontinuous recesses are provided on the circumference of the annular rib forming the rim guard, the surface area of the rim guard is increased compared to the conventional rim guard, and the heat dissipation is excellent and the tire An increase in weight can be suppressed.

In the pneumatic tire according to the present invention, the meridional cross-sectional shape of the annular rib is such that the length of the outer side in the radial direction is larger than the length of the inner side in the radial direction, so that cracking due to strain can be prevented. In the pneumatic tire according to the present invention, the length of the radially outer side of the meridional section of the annular rib is 1.2 times the length of the radially inner side.
It is preferable to be 2 to 2. When this value is less than 1.2, cracks are likely to occur in the rim guard of the annular rib, and when it is more than twice, the tire weight increase cannot be suppressed.

In the pneumatic tire according to the present invention, the radially inner side of the meridional section of the annular rib is formed with a radius of curvature much smaller than the radius of curvature forming the radially outer side, and the radially outer side. Is preferably formed in a substantially straight line in order to prevent the apex of the rim guard of the annular rib from forming an acute angle, prevent cracks from occurring, and suppress an increase in tire weight.

In the pneumatic tire according to the present invention, the surface area of the circumferentially discontinuous recess is approximately the same as the surface area of the annular rib minus the surface area of the circumferentially discontinuous recess. It is preferable from the viewpoint of the balance between the heat radiation effect due to the increase in the surface area, the strength of the annular rib, and the rubber amount (tire weight) of the annular rib.

In the pneumatic tire according to the present invention, the surface area of the circumferentially discontinuous recess corresponds to the circumferentially discontinuous recess of the annular rib before the circumferential discontinuous recess is provided. It is preferably 110 to 150% of the surface area of the portion. If this value is smaller than 110%, the heat dissipation effect is insufficient and the weight of the tire increases, and if it is larger than 150%, the function of the rim guard of the annular rib is not exerted.

In the pneumatic tire according to the present invention, in order to maintain the function of the rim guard while suppressing an increase in tire weight, the circumference of the annular rib is maintained so as not to impair the circumferential continuity of the annular rib. It is preferable to provide a number of discontinuous recesses in the direction.

In the pneumatic tire according to the present invention, in order to prevent cracks from occurring, it is preferable that the circumferentially discontinuous recesses provided on the circumference of the annular rib be circular or elliptical.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Tires according to embodiments of the present invention and conventional tires will be described below with reference to the drawings. The tire size is 235 / 45R17, and the aspect ratio is 45%.

The tire of Example 1 shown in FIG. 1 has an annular rib (R) in which rubber bulges outward in the tire axial direction between a position (M) near the maximum tire width and a rim line (L).
It is equipped with a rim guard. The meridional cross-sectional shape of the annular rib (R) is substantially triangular as shown in the figure,
The maximum thickness (W) is 6.1 mm, the radially outer side (1) has a length of 18.7 mm, and the radially inner side (2) has a length of 13 mm, and thus the radially outer side The length of the side (1) is the inner side in the radial direction (2)
The length is 1.43 times. The radius of curvature that forms the radially outer side (1) is 200 mm, and the radius of curvature that forms the radially outer side (2) is 15 mm. Height of the radial outer end of the annular rib (R) (H
2) is 47 mm, and the height (H1) to the position of the maximum thickness (W) is 28.5 mm. The annular rib (R) has
The circumferentially discontinuous elliptical recesses (D) are provided at equal intervals of 45 on the circumference so as not to impair the circumferential continuity of the annular rib (R). The major axis length of this elliptical recess (D) is 14.9 mm, the minor axis length is 8.2 mm, and the depth is 1.5 mm. The surface area of the elliptical recess (D) is equal to that of the annular rib (R) before the provision of this elliptical recess (D).
129% of the surface area of the part corresponding to the oval recess (D)
Is.

The tire of Example 2 shown in FIG. 2 has an annular rib (R) in which rubber is bulged outward in the axial direction of the tire between the vicinity of the maximum tire width (M) and the vicinity of the rim line (L).
It is equipped with a rim guard. The meridional cross-sectional shape of the annular rib (R) is substantially triangular as shown in the figure,
The maximum thickness (W) is 6.1 mm, the radially outer side (1) has a length of 18.7 mm, and the radially inner side (2) has a length of 13 mm, and thus the radially outer side The length of the side (1) is the inner side in the radial direction (2)
The length is 1.43 times. The radius of curvature that forms the radially outer side (1) is 200 mm, and the radius of curvature that forms the radially outer side (2) is 15 mm. Height of the radial outer end of the annular rib (R) (H
2) is 47 mm, and the height (H1) to the position of the maximum thickness (W) is 28.5 mm. The annular rib (R) has
The large and small elliptical recesses (D1, D2) which are discontinuous in the circumferential direction are provided at two equal intervals on the circumference in two rows so as not to impair the circumferential continuity of the annular rib (R). The major axis of the large elliptical recess (D1) has a length of 16.
4mm, minor axis length 3.0mm, depth 1.5mm
And the major axis length of the small elliptical recess (D2) is 1
1.2mm, minor axis length 3.0mm, depth 1.5
mm. The surface area of the large oval recess (D1) is
Annular rib (R) before forming this elliptical recess (D1)
1 of the surface area of the portion corresponding to the elliptical recess (D1)
At 11%, the surface area of the small elliptical recess (D2) is the annular rib (R) before the provision of this elliptical recess (D2).
1 of the surface area corresponding to the elliptical recess (D2) of
13%.

The tire of Example 3 shown in FIG. 3 has an annular rib (R) in which rubber bulges outward in the axial direction of the tire between the vicinity of the maximum tire width (M) and the vicinity of the rim line (L).
It is equipped with a rim guard. The tire shown in FIG. 4 is a conventional tire, but the tire of Example 3 provided with a rim guard made of an annular rib (R) before forming the recesses (D1, D2) is shown in FIG. Almost the same as the tire of the conventional example, a substantially trapezoidal annular rib (R) having a meridional cross-sectional shape is continuously provided in the circumferential direction between the vicinity of the maximum tire width (M) and the vicinity of the rim line (L). Has been.
The meridional cross-sectional shape of the annular rib (R) is almost trapezoidal as shown in the figure, the maximum thickness (W) is 6.1 mm, and the length of the side (1) on the outer side in the radial direction is 13.5 mm. The length of the side (2) on the inner side in the direction is 8.98 mm, and thus the length of the side (1) on the outer side in the radial direction is 1.5 times the length of the side (2) on the inner side in the radial direction. The radius of curvature forming the radially outer side (1) is 15.1 mm, and the radius of curvature forming the radially outer side (2) is 8 mm. The height (H2) of the radially outer end of the annular rib (R) is 47.3 mm, and the height (H3) to the radially innermost position of the radially outer side (1) is 35.9 mm. Yes, the height of the radially inner side (2) to the radially outermost position (H1)
Is 28.5 mm. Now, returning to FIG. 3, the third embodiment
In the annular rib (R) of the tire, there are two rows of concave portions (D1, D2) which are discontinuous in the circumferential direction and are arranged at regular intervals of 60 on the circumference so as not to impair the circumferential continuity of the annular rib (R). It is provided over. Recessed portion radially outward (D1)
Of the annular rib (R) before the recess (D1) is provided is equal to 12 of the surface area of the recess (D1).
At 5.7%, the surface area of the recess (D2) on the inner side in the radial direction is equal to that of the annular rib (R) before the recess (D2) is provided.
It is 135.9% of the surface area of the portion corresponding to the recess (D2). H4 is 32 mm.

The tire shown in FIG. 4 is a conventional tire.

In order to compare the tires of Examples 1 to 3 with the tire of the conventional example, tests were conducted under the same conditions. The test condition is a regular internal pressure of 2.4 kg / cm specified by JIS.
After running for 2 hours at a constant speed mode with ² and a regular load of 650 kg, the temperature inside the rim guard consisting of the annular rib (R) was measured at 4 points on the circumference, and the average value was calculated as the value of the tire of the conventional example. Is set to 100 and is shown in Table 1 in index form. The smaller the number, the lower the temperature.

[0025]

[Table 1]

[0026]

According to the present invention, it is possible to provide a tire provided with a rim guard, which is excellent in heat dissipation effect of the tire / bead portion and has good fuel efficiency.

[Brief description of drawings]

FIG. 1 is a front view of a rim guard according to the present invention and a cross-sectional view of an essential part thereof.

FIG. 2 is a front view of a rim guard according to the present invention and a cross-sectional view of an essential part thereof.

FIG. 3 is a front view of a rim guard according to the present invention and a sectional view of an essential part thereof.

FIG. 4 is a front view of a rim guard of a conventional example and a cross-sectional view of a main part thereof.

[Explanation of symbols]

 D concave portion L rim line M tire maximum width position R annular rib 1 radial outer side 2 radial inner side

Claims (8)

[Claims] 1. An inflator having an aspect ratio of 60 or less, which is provided with a rim guard made of an annular rib having rubber bulging outward in the tire axial direction between the vicinity of the maximum tire width and the vicinity of the rim line. In the tire, (1) the meridional cross-sectional shape of the annular rib is triangular or trapezoidal, or substantially triangular or substantially trapezoidal, and the length of the radially outer side is greater than the length of the radially inner side, and (2)
A pneumatic tire having a large number of circumferentially discontinuous recesses provided on the circumference of the annular rib. 2. The pneumatic tire according to claim 1, wherein the meridional cross-sectional shape of the annular rib is substantially trapezoidal. 3. The length of the radially outer side of the meridional section of the annular rib is 1.2 times the length of the radially inner side.
The pneumatic tire according to claim 1 or 2, wherein the pneumatic tire has a doubling rate. 4. The radial inner side of the meridional section of the annular rib is formed with a radius of curvature much smaller than the radius of curvature forming the radial outer side, and the radial outer side is substantially a straight line. It is formed, The pneumatic tire of Claim 1 thru | or 3 characterized by the above-mentioned. 5. The surface area of the circumferentially discontinuous recess is approximately the same as the surface area of the annular rib minus the surface area of the circumferentially discontinuous recess.
The pneumatic tire according to any one of 4 to 4. 6. The surface area of the circumferentially discontinuous recess is 110 of the surface area of a portion of the annular rib corresponding to the circumferentially discontinuous recess before forming the circumferentially discontinuous recess. % To 150%, The pneumatic tire according to claim 1, wherein 7. The plurality of circumferentially discontinuous recesses are provided on the circumference of the annular rib so as not to impair the circumferential continuity of the annular rib. Pneumatic tires. 8. The pneumatic tire according to claim 7, wherein the circumferentially discontinuous recess provided on the circumference of the annular rib is circular or elliptical.