JPH11165504A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire for air craft, in which partial wearing is effectively avoided or restrained. SOLUTION: In a pneumatic tire provided with bead cores, carcasses, treads and at least two main grooves extending in the peripheral direction in parallel with each other, with the tire charged with regular inner pressure, the axial cross section contour is formed by an arc of a single or actually single curvature radius R, and the radial direction surface of the peripheral direction rib 4 adjacent to the inside of a peripheral direction main groove 2 in the axis direction of the tire is chamfered by the arc of a radius S of curvature, which is smaller than a radius R of curvature of the cross section contour of the whole of a tread, so as to become shallower gradually as approaching the inside in the axial direction of the tire from the side of the main groove 2 in the peripheral direction, and the chamfering width (w) is 55 to 80% of the rib width W of a peripheral directional rib 4, and chamfering depth is 20 to 50% of the depth of the peripheral main groove.

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 bead core provided on a pair of right and left bead portions and extending from one bead portion to the other bead portion. A carcass wound and moored to a bead portion, and at least two circumferential directions extending continuously or substantially parallel to the circumferential direction, comprising a tread disposed radially outside the crown portion of the carcass. A main groove is provided on both sides of the tread with the tire equator interposed therebetween, and in a state where the tire is filled with a normal internal pressure, an outer contour in the axial cross section of the tread is a single or substantially single circular arc having a radius of curvature R. The present invention relates to a pneumatic tire used in high-speed running, and more particularly to a pneumatic tire for an aircraft.

[0002]

2. Description of the Related Art In general, a conventional pneumatic tire for high-speed running has at least two circumferential grooves extending continuously in a circumferential direction or substantially in a circumferential direction of the tire, and an axial direction of the tire by the circumferential grooves. A plurality of circumferential ribs extending in the circumferential direction of the tire formed at intervals in the tread,
The outer contour of the tread in the tire axial section is formed from a relatively large single or substantially single radius of curvature arc. In the pneumatic tire as described above, the outermost rib in the axial direction of the tire, that is, the shoulder rib, tends to wear relatively early.

The cause of the above-mentioned shoulder drop wear is that the radius of curvature forming the outer contour in the tire axial section of the tread is not infinite, and therefore, the outer diameter of the tread between the center portion and the shoulder portion of the tread is reduced. There is a difference.
In other words, the center part and the shoulder part of the tread, which touch the road surface at the stepping position at the same time, move the same distance up to the kicking position with the rolling of the tire, but the angular speed at which the tire rotates at both the center part and the shoulder part Since the shoulder portion is the same, the shoulder portion having a small outer diameter rubs against the road surface to obtain the same moving distance as the center portion having a large outer diameter, and drag wear occurs. When a pneumatic tire rotates at a very high speed, a standing wave (standing wave) may be generated. When a standing wave occurs, the rolling resistance of the tire rapidly increases due to the energy for wave generation, and the temperature also rises sharply, directly leading to the destruction of the tire. Therefore, in a pneumatic tire for high-speed running, the radius of curvature forming the outer contour in the tire axial direction of the tread is reduced to prevent the occurrence of a standing wave. Therefore, compared to general pneumatic tires, the difference in outer diameter between the center part and the shoulder part of the tread tends to be larger in high-speed running pneumatic tires such as aircraft pneumatic tires, and the shoulder part has drag wear. And uneven wear called so-called shoulder wear is likely to occur.

In order to prevent the occurrence of uneven wear referred to as shoulder dropping wear, as disclosed in Japanese Patent Laid-Open No. 81305/1992, at least one extending continuously or substantially in parallel to the circumferential direction. Two circumferential main grooves are provided on both sides of the tread with the tire equator interposed therebetween, and when the tire is filled with normal internal pressure, the tread has a single or substantially single radius of curvature in the axial cross-sectional outer contour. In the pneumatic tire formed by the arc of R, the radially outer surface of the circumferential rib adjacent to the axially inner side of the circumferential main groove extends in the tire axially inward direction from the circumferential main groove side. A pneumatic tire that is chamfered by an arc having a radius of curvature S smaller than the radius of curvature R so as to gradually become shallow has been proposed. However, as described above, when chamfering the surface of the circumferential rib adjacent to the inside of the circumferential main groove in the tire axial direction with an arc having a small radius of curvature S, the chamfer width w and the chamfer depth d must be set appropriately. In other words, if the shape of the rib after chamfering is not properly set, the effect of preventing the occurrence of uneven wear is small or the wear life is shortened.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned disadvantages of the prior art, and is called shoulder drop wear, in which the axially outermost ribs or shoulder ribs of the tire are worn early. An object of the present invention is to provide a long-life pneumatic tire for aircraft, in which uneven wear is effectively prevented or suppressed.

[0006]

In order to achieve the above object, a tire according to the present invention comprises a bead core provided on a pair of left and right bead portions, and extends from one bead portion to the other bead portion. A carcass wound around the bead core and anchored to the bead portion, and a tread arranged radially outward of a crown portion of the carcass, and extending continuously in parallel or substantially parallel to the circumferential direction. In a pneumatic tire in which two circumferential main grooves are provided on both sides of the tread with the tire equator interposed therebetween, (1) when the tire is filled with a normal internal pressure, (2) The radially outer surface of the circumferential rib adjacent to the circumferential main groove inward in the tire axial direction is formed by a single or substantially single circular arc having a radius of curvature R from the circumferential main groove side. Tire axis It is chamfered with an arc having a smaller radius of curvature S than the radius of curvature R of the outer contour of the cross section of the entire tread so as to gradually become shallower toward the inner side. 55 to 80% of width W
In the pneumatic tire, the chamfer depth d is 20 to 50% of the groove depth D of the circumferential main groove.
In the tire of the present invention, the chamfer width w is greater than 60% and equal to or less than 80% of the rib width W of the circumferential rib.
The side wall of the circumferential main groove and the radially outer surface of the chamfered circumferential rib are smoothly connected with a small radius of curvature r, and the circumferential main groove is linearly or substantially circumferentially formed. It preferably extends continuously in a straight line.

[0007] Pneumatic tires are available in JATMA (Japan), TRA (US) and ET, depending on their size.
It is used by being mounted on a standard rim specified in a standard issued by RTO (Europe) or the like, and this standard rim is usually called a regular rim. In this specification, according to the conventional name, "regular rim" is defined as a tire and rim association of the United States, TRA, which is 1
YEAR BOOK or AIR issued in 997
Refers to the standard rim in the application size ply rating defined in CRAFT YEARBOOK,
"Normal internal pressure" refers to the air pressure corresponding to the maximum load in the applicable size ply rating. Therefore, in the present specification, "the state in which the tire is filled with the normal internal pressure" means that the tire is rim assembled to the "normal rim" and the "normal internal pressure"
Refers to the state filled with.

The pneumatic tire according to the present invention is configured as described above. In particular, when the tire is filled with a normal internal pressure, (1) the tread has a single or substantially single outer cross-sectional profile in the axial direction. (2) The radially outer surface of the circumferential rib adjacent to the circumferentially inner side of the circumferential main groove in the tire axial direction faces inward in the tire axial direction from the circumferential main groove side. The radius of curvature S is smaller than the radius of curvature R of the outer contour line of the cross section of the entire tread so as to gradually become shallower.
(3) The chamfer width w is 55 to 80% of the rib width W of the circumferential rib, preferably 60%.
Since it is larger and the chamfering depth d is 20 to 50% of the groove depth D of the circumferential main groove, the disadvantage of the prior art is solved, and the outermost rib in the axial direction of the tire, that is, the shoulder
A pneumatic tire for an aircraft having a long life and effectively preventing or suppressing uneven wear called shoulder dropping wear in which ribs are worn early can be obtained.

The pneumatic tire for aircraft according to the present invention comprises:
As described above, the chamfer width w of the circumferential rib adjacent to the circumferential main groove on the inner side in the tire axial direction is 5 times the rib width W of the circumferential rib.
If the chamfer width w is smaller than 55% of the rib width W of the circumferential rib, the effect of preventing or suppressing uneven wear is small. On the other hand, the chamfer width w is smaller than that of the circumferential rib. If it is larger than 80% of the rib width W, the wear life of the tire is shortened. From the viewpoint of the wear life of the tire, in the pneumatic aircraft tire according to the present invention, the chamfer width w of the circumferential rib adjacent to the circumferential main groove on the inner side in the tire axial direction is 60 times the rib width W of the circumferential rib. % Is desirable.

In the pneumatic tire for an aircraft according to the present invention, as described above, the chamfer depth d of the circumferential rib adjacent to the circumferential main groove inward in the tire axial direction is equal to the groove depth D of the circumferential main groove. If the chamfer depth d is less than 20% of the groove depth D of the circumferential main groove, the effect of preventing or suppressing the occurrence of uneven wear is small, while the chamfer depth d is 20% to 50%. If it is larger than 50% of the groove depth D of the circumferential main groove, the wear life of the tire is shortened. Note that the chamfer depth d is
As shown in FIG. 2, the groove depth D is measured in the radial direction (radial direction), that is, the direction perpendicular to the tire rotation axis, and the groove depth D is measured in the normal direction set on the tread surface. Before the circumferential rib adjacent to the inner side of the direction main groove in the tire axial direction is chamfered, it is measured in a normal direction standing on the virtual tread surface, so to speak.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, tires of Examples 1 to 3 and Conventional Examples 1 to 3 according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing the outer contour of the tread of the tire of Examples 1 to 3 according to the present invention in the axial section. FIG. 2 is a drawing showing the measuring directions of the chamfer depth d and the groove depth D.

The tire according to the first embodiment of the present invention has two circumferential shoulder grooves 1 extending linearly and continuously in parallel to the circumferential direction, and a tire parallel to the circumferential direction inside the tire from the circumferential shoulder grooves 1. The tread is provided with two circumferential center grooves 2 extending linearly and continuously, and the five circumferential ribs 3 extending linearly and continuously in the circumferential direction by the four circumferential grooves 1 and 2 are provided. 4 and 5 are formed in the tread. That is, a pair of left and right shoulder circumferential ribs 3 is formed between the circumferential shoulder groove 1 and the tread end, and an inner circumferential rib 4 is formed between the circumferential shoulder groove 1 and the circumferential center groove 2. A central circumferential rib 5 is formed between a pair of left and right circumferential center grooves 2. The tire of Example 1 according to the present invention is an aircraft tire, and the tire size is H49 × 19.0-22 32PR.
A (199) issued by TIRE AND RIM ASSOCIATION, INC.
According to the standard defined in the 7-year version of AIRCRAFT YEAR BOOK, the normal load, ie, MAX. LOA
D is 56600 lbs and the normal internal pressure, ie, UNLOA
DED INFLATION is 205 psi. With the tire of Example 1 according to the present invention filled with the normal internal pressure, (1) the outer contour line in the axial cross section of the tread is formed by a single arc having a single radius of curvature R = 380 mm, and (2) the outermost The radially outer surface of the circumferential rib, that is, the inner circumferential rib 4 adjacent to the circumferential groove, that is, the circumferential shoulder groove 1, in the tire axial direction, gradually increases from the circumferential main groove 1 side toward the axial inside of the tire. Is chamfered by an arc having a radius of curvature S = 140 mm smaller than the radius of curvature R = 380 mm of the outer contour line of the entire tread, and (3) the chamfer width w is equal to the rib width W of the circumferential rib. 6 of
At 4.6%, the chamfer depth d is 35.1% of the groove depth D of the circumferential main groove. As shown in FIG. 2, the side wall of the circumferential main groove, that is, the circumferential shoulder groove 1, and the radial outer surface of the chamfered circumferential rib, that is, the inner circumferential rib 4, are smoothly connected with a small radius of curvature r = 5 mm, as shown in FIG. Have been.

A tire according to a second embodiment of the present invention includes two circumferential shoulder grooves 1 extending linearly and continuously in parallel with the circumferential direction, and a tire parallel to the circumferential direction inside the tire from the circumferential shoulder grooves 1. The tread is provided with two circumferential center grooves 2 extending linearly and continuously, and the five circumferential ribs 3 extending linearly and continuously in the circumferential direction by the four circumferential grooves 1 and 2 are provided. 4 and 5 are formed in the tread. That is, a pair of left and right shoulder circumferential ribs 3 is formed between the circumferential shoulder groove 1 and the tread end, and an inner circumferential rib 4 is formed between the circumferential shoulder groove 1 and the circumferential center groove 2. A central circumferential rib 5 is formed between a pair of left and right circumferential center grooves 2. The tire of Example 2 is an aircraft tire, and the tire size is H44.5.
× 16.5-21 26PR, so TRA (TIRE
AND RIM ASSOCIATION, INC.), According to the standard specified in the 1997 edition of AIRCRAFT YEAR BOOK, the normal load, that is, MAX. LOAD is 41
At 100 lbs, normal internal pressure, ie UNLOADED
INFLATION is 198 psi. With the tire of Example 2 according to the present invention filled with the normal internal pressure, (1) the outer contour line in the axial cross section of the tread is formed by a single arc having a single radius of curvature R = 360 mm, and (2) the outermost The radially outer surface of the circumferential rib, that is, the inner circumferential rib 4 adjacent to the circumferential groove, that is, the circumferential shoulder groove 1, in the tire axial direction, gradually increases from the circumferential main groove 1 side toward the axial inside of the tire. So as to be shallower than the radius of curvature R = 360 mm of the outer contour line of the entire tread, which is chamfered by an arc having a smaller radius of curvature S = 100 mm,
(3) The chamfer width w is 66.6 of the rib width W of the circumferential rib.
%, The chamfering depth d is 37.degree. Of the groove depth D of the circumferential main groove.
2%. Circumferential main groove, that is, circumferential shoulder groove 1
2 and the chamfered circumferential ribs, that is, the radially outer surfaces of the inner circumferential ribs 4, are smoothly connected with a small radius of curvature r = 5 mm as shown in FIG.

The tire according to the third embodiment of the present invention has two circumferential shoulder grooves 1 extending linearly and continuously in parallel with the circumferential direction, and a tire inner side of the circumferential shoulder groove 1 and parallel to the circumferential direction. The tread is provided with two circumferential center grooves 2 extending linearly and continuously, and the five circumferential ribs 3 extending linearly and continuously in the circumferential direction by the four circumferential grooves 1 and 2 are provided. 4 and 5 are formed in the tread. That is, a pair of left and right shoulder circumferential ribs 3 is formed between the circumferential shoulder groove 1 and the tread end, and an inner circumferential rib 4 is formed between the circumferential shoulder groove 1 and the circumferential center groove 2. A central circumferential rib 5 is formed between a pair of left and right circumferential center grooves 2. The tire of Example 3 is an aircraft tire, and the tire size is 36 × 11.
22PR, TRA (TIRE AND RIM ASSOCIAT
ION, INC.) Published by AIRCRAFT in 1997
According to the standard set forth in YEAR BOOK, the normal load, that is, MAX. LOAD is 23300lbs,
Normal internal pressure, ie, UNLOADED INFLATIO
N is 200 psi. With the tire of Example 3 according to the present invention filled with the normal internal pressure, (1) the outer contour of the tread in the axial cross section has a single radius of curvature R = 320 mm.
(2) The radially outer surface of the circumferential rib, ie, the inner circumferential rib 4, which is adjacent to the outermost circumferential groove, that is, the circumferential shoulder groove 1, in the tire axial direction, is the circumferential main groove 1. The radius of curvature S is smaller than the radius of curvature R = 320 mm of the outer contour of the cross section of the entire tread so that the radius of curvature is gradually reduced from the side toward the inside in the axial direction of the tire.
(3) The chamfer width w is 66.6% of the rib width W of the circumferential rib, and the chamfer depth d is 34.4 of the groove depth D of the circumferential main groove. %. As shown in FIG. 2, the side wall of the circumferential main groove, ie, the circumferential shoulder groove 1, and the radially outer surface of the chamfered circumferential rib, ie, the inner circumferential rib 4, have a small radius of curvature r = 5 mm.
It is tied smoothly.

In the tire of Conventional Example 1, the chamfer width w is 50.0% of the rib width W of the circumferential rib, and the chamfer depth d is 18.2% of the groove depth D of the circumferential main groove. Except that
The tire has substantially the same configuration as the tire of the first embodiment.
In the tire of Conventional Example 2, the chamfer width w is 50.2% of the rib width W of the circumferential rib, and the chamfer depth d is 14.5% of the groove depth D of the circumferential main groove. Except for Example 2 above
This is a tire having substantially the same configuration as that of the tire. In the tire of Conventional Example 3, the chamfer width w is 50.
5%, and the chamfer depth d is one of the groove depth D of the circumferential main groove.
Except for 6.4%, the tire has substantially the same configuration as the tire of the third embodiment.

The tires of Examples 1 to 3 and the tires of Conventional Examples 1 to 3 according to the present invention were subjected to a comparative evaluation test of uneven wear resistance. The comparison test condition between the tire of Example 1 and the tire of Conventional Example 1 was 14.4 kg of internal pressure.
/ Cm ² at a load of 25700 kg and a speed of 64 k
A straight run of 10 km at m / h is one cycle,
In a repeated indoor drum test, the diameter difference (step-down) between the shoulder circumferential rib 3 and the inner circumferential rib 4 was measured after the test was completed. As shown in FIG. 3, this step-down is performed in the radial direction between the position A where the center line of the circumferential shoulder groove 1 is 10 mm inside the inner circumferential rib 4 and the position B where the shoulder circumferential rib 3 has the maximum diameter. Is the distance. The comparative test conditions for the tire of Example 2 and the tire of Conventional Example 2 were such that the internal pressure was 13.9 kg / cm ² and the load was 18600 kg.
The test conditions are the same as those of the tire of Example 1 and the tire of Conventional Example 1 except that the weight is kg. The comparative test conditions of the tire of Example 3 and the tire of Conventional Example 3 were such that the internal pressure was 14.1.
The test conditions are the same as those of the tire of Example 1 and the tire of Conventional Example 1 except that the load is 10600 kg at kg / cm ² .

As a result of the above-described evaluation test for uneven wear resistance, in the comparative test between the tire of Example 1 and the tire of Conventional Example 1, the step-down of the tire of Conventional Example 1 is expressed as an index, with 100 being the index. The tire step down was 85. In a comparison test between the tire of Example 2 and the tire of Conventional Example 2, the step down of the tire of Example 2 was 82 when the step down of the tire of Conventional Example 2 was expressed as an index, assuming 100. In a comparison test between the tire of Example 3 and the tire of Conventional Example 3, the step down of the tire of Example 3 was 88 when the step down of the tire of Conventional Example 3 was represented by an index, where 100. In each case, the smaller the number, the smaller the diameter difference (step-down) between the shoulder circumferential ribs 3 and the inner circumferential ribs 4, indicating that the tire is more excellent in uneven wear resistance.

[0018]

From the results of the above comparative tests, it can be seen that the tire of the example according to the present invention is a tire having more excellent uneven wear resistance than the conventional tire.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an outer contour (left half) of an axial cross section of a tire.

FIG. 2 is a schematic view showing a measurement direction of a chamfer depth d and a groove depth D.

FIG. 3 is a drawing showing a step-down measurement method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Circumferential shoulder groove 2 Circumferential center groove 3 Shoulder circumferential rib 4 Inner circumferential rib 5 Central circumferential rib d Chamfer depth w Chamfer width D Groove depth of circumferential shoulder groove W Rib width of inner circumferential rib

Claims (4)

[Claims] A bead core provided in a pair of left and right bead portions, a carcass extending from one bead portion to the other bead portion, wound around the bead core and moored to the bead portion, A tread disposed radially outwardly of a crown portion of a carcass, wherein three or more circumferential grooves extending continuously or substantially parallel to the circumferential direction are provided on the tread. (1) the outer contour of the tread in the axial cross-section is formed by a single or substantially single circular arc having a radius of curvature R, and (2) the tire in the outermost circumferential groove. The radially outer surface of the circumferential rib adjacent to the inner side in the axial direction is
(3) Beveled with an arc having a radius of curvature S smaller than the radius of curvature R of the outer contour of the cross section of the entire tread so as to gradually become shallower from the circumferential main groove side toward the inside in the axial direction of the tire. The chamfer width w is 55 which is the rib width W of the circumferential rib.
And the chamfering depth d is the groove depth D of the circumferential main groove.
20% to 50% of the pneumatic tire. 2. The pneumatic tire according to claim 1, wherein the chamfer width w is greater than 60% and equal to or less than 80% of a rib width W of the circumferential rib. 3. The method according to claim 1, wherein a side wall of the circumferential main groove and a radially outer surface of the chamfered circumferential rib are smoothly connected with a small radius of curvature r. Pneumatic tire. 4. The pneumatic tire according to claim 1, wherein said circumferential main groove extends continuously or substantially linearly in the circumferential direction.