JPH0672108A - Pneumatic tire for construction vehicle - Google Patents

Abstract

PURPOSE:To prevent a bead part from the occurrence of cracks and improve durability while holding traveling performance and rim assembling operability by elongating the contact length of flange contact surface of the bead part with a rim flange of a rim and providing an outward bulging part in the radial outside of a separation point where the outer side surface and the rim flange are separated from each other. CONSTITUTION:While a rim flange 13 formed of an arc of radius of curvature RF in which the inner surface 14 of an erect wall part 15 locates the center Fo of curvature on the tire axial direction line XF passing through a radial outer point C is provided with an arcuate surface 16. The tire comprises a flange contacting surface 6 consisting of a lower bead surface 4 in contact with the inner surface 14 of the rim flange 13 and extending to an outer point C, and flange arcuate outer surface 5 extending from the outer point C, passing through the center Fo of curvature and reaching a position B at an angle alpha to the tire axial direction line XF. The position B is located between an inner arcuate point B70 making 70 deg. of angle to the axial direction line XF of the tire and an outer arcuate point V85 making 85 deg. of angle to the axial direction line XF. Further, an outward bulging part 10 contiguous smoothly to an flange arcuate outer surface 5 is additionally provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention prevents so-called rim chafing in which foreign matter enters the interface where the outer surface of the bead portion of the tire and the inner surface of the rim flange of the rim contact each other without deteriorating the running performance. The present invention relates to a pneumatic tire for a construction vehicle capable of maintaining stability of traveling by preventing damage to a bead portion and maintaining rim assembly accuracy for a long period of time.

[0002]

2. Description of the Related Art Construction vehicles such as shovel loaders and dump trucks often travel on rough terrain, and their tires are often subjected to heavy loads and impact. Therefore, the tires used for these construction vehicles are formed to have a large size and withstand a heavy load, and the rim assembly with the rim is made firm.

[0003]

However, when the conventional tire is assembled on the rim, as shown in FIG. 3, the outer wall surface b of the bead portion a is wedge-shaped on the outside of the separation point c at which it separates from the rim flange f of the rim j. Space d is formed. Also, in this space d, a foreign substance g
In many cases, so-called rim chafing occurs, which causes the outer wall surface to be damaged and the tire to be damaged. Further, there is a problem that the steering stability of the tire deteriorates due to the deterioration of the rim assembly accuracy.

The hardness of the clincher rubber is increased to prevent damage to the outer wall surface. It is conceivable to increase the thickness of the bead part, but in the former case, the rigidity of the bead part becomes excessive,
The running performance of the tire is deteriorated, and in the latter case, the weight of the tire is increased, the cost is increased, and the workability of assembling the rim is deteriorated.

The inventor has conducted research to prevent rim chafing while maintaining various running performances of tires and maintaining workability of assembling the rim, and as a result, the flange contact surface of the bead portion and the rim of the rim are By making the contact length with the flange longer than the conventional one, and by providing a bulge portion that bulges outwardly on the outside in the radial direction of the separation point where the side outer surface and the rim flange are separated, tire running performance, rim assembly The inventors have found that rim chafing can be prevented from occurring without lowering workability, and have completed the present invention.

The present invention enhances the adhesion between the bead portion of the tire and the rim flange of the rim while maintaining the running performance of the tire and the workability of assembling the rim to prevent rim chafing,
An object of the present invention is to provide a pneumatic tire for a construction vehicle capable of preventing tire durability and rim displacement.

[0007]

According to the present invention, a rim flange of a rim rises radially outward from a rim base in a tire meridional section in a normal internal pressure state in which the rim is assembled to a normal rim and filled with a normal internal pressure. The standing wall portion has an inner surface facing the tire, and the inner surface facing the tire is composed of an arc having a radius of curvature RF whose center of curvature Fo is located on a tire axial direction line XF passing through a radially outward point C of the standing wall portion, and the tire shaft. And a bead lower surface that is in contact with the inner surface of the standing wall portion of the rim flange and that extends to the outer point C, and that has an arc surface that curves outward in the direction and has an outer surface shape that extends from the tire maximum width point Mo of the tire to the bead bottom portion. , An arc point B ₇₀ which forms an angle α of 70 ° with the tire axial direction line XF from the lower point C on the arc surface of the rim flange through the curvature center Fo.
And a center of curvature So on a tire axial direction line XM passing through the maximum width point Mo of the tire and a flange contact surface consisting of an outer surface of the flange arc extending up to an outer arc point B ₈₅ forming an angle of 85 °. In addition, the inner and outer circular arc points B ₇₀ , on the reference plane formed by the circular arc having the radius of curvature RM that connects the range of the tire maximum width Mo and the inner circular arc point B ₇₀ to the outer circular arc point B ₈₅ . A pneumatic tire for a construction vehicle, comprising a side outer surface provided with an outer bulge smoothly connecting to the outer surface of the flange arc between B ₈₅ .

The radius of curvature of the outer bulge is a radius of curvature R of the arc surface of the rim flange in the meridional section of the tire.
The maximum distance H of the outer surface of the outer bulge portion from the reference line is in the range of 1.5 to 4% of the tire cross-section height TH. preferable.

[0009]

The flange contact surface keeps contact with the inner surface of the rim flange of the rim between the bottom of the bead and the inner arc point B _{70 of the} flange contact surface and the outer arc point B ₈₅ . Inner arc point B ₇₀ , outer arc point B located on the arc surface of the rim flange
₈₅ are respectively located on the arcs that pass through the center Fo of the arc and form an angle of 70 ° and 85 ° with the tire axial direction line XF, and the range between the inner arc point B ₇₀ and the outer arc point B ₈₅ is , The contact area between the side outer surface and the rim flange is increased compared to the conventional tire in which the inner surface of the rim flange and the outer surface of the side are separated from each other in the range of 40 to 60 °, resulting in close contact between the both. As a result of the increased strength, foreign matter such as earth and sand can be prevented from entering the interface between the two.

Further, on the outer surface of the side, there is provided an outer bulge portion which is smoothly continuous between the circular arc points B _{70 to} B ₈₅ . The outer bulge portion closes a gap interposed between the side outer surface and the inner surface of the rim flange on the outer side of the reference surface, and can further effectively prevent foreign matter from entering the flange contact surface.

In addition, by providing the outer bulge portion, the thickness of the bead portion outside the reference surface is increased, and the rigidity of the bead portion is increased, whereby the entry of foreign matter can be prevented more effectively.

[0012] arc forming the curvature radius RM is found on the flange arc outer surface, if from the inner arc point B ₇₀ continuous with inwardly, the inner surface and the side outer surface of the rim flange outwardly of the inner circular arc point B ₇₀ As a result, a large gap is created between the two surfaces, and the foreign matter is caught between the two surfaces, and the foreign matter enters the flange contact surface. As a result, the flange contact surface is damaged, and this damage grows, resulting in damage to the bead portion. When continuing the outside than Matasoto arc point B _85, the thickness of the bead portion, of the outer arc point B _85, will be extreme step outside occurs, adversely change the spring constant of the tire Not only will the various running performances be reduced, but the weight of the tire will be increased, and the workability of assembling the rim will be reduced.

As described above, according to the present invention, by organically integrating the above-mentioned components, the outer surface of the bead portion is not affected without causing a significant change in the running performance of the tire and without causing a significant increase in the tire weight. It is possible to prevent so-called rim chafing in which foreign matter enters the interface where the rim flange and the inner surface of the rim flange contact each other, and to improve durability by preventing the occurrence of cracks in the bead part, and to eliminate rim displacement and to maintain stability over time. Can be prevented from decreasing.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 and 2, a pneumatic tire 1 for a construction vehicle (hereinafter referred to as a tire 1) includes a tread portion 22, a sidewall portion 23 extending from both ends thereof inward in a tire radial direction, and a tire radius of the sidewall portion 23. And a bead portion 24 connected to the inner end in the direction. The pneumatic tire 1 for a construction vehicle has a main body portion 26a extending from the tread portion 22 through the sidewall portion 23 to the bead portion 24.
A carcass 26 provided with a turn-back part 26b that turns back around the bead core 25 of the bead part 24 from the inner side in the tire axial direction to the outer side, and the inner carcass 2 of the tread part 22.
6 and a breaker 27 disposed on the outer side in the radial direction, and a bead apex 28 having a triangular shape extending outward in the tire radial direction of the bead core 5 and between the main body portion 26a of the carcass 26 and the winding portion 26b. increase.

The carcass 26 comprises a plurality of carcass cords in a bias arrangement inclined at an angle of 25 to 45 ° with respect to the tire equator CO. In this embodiment, four carcass plies are used. An organic fiber cord such as rayon, polyester, aromatic polyamide fiber is used.

The breaker 27 is composed of one ply in this embodiment, and the ply is formed in substantially the same manner as the carcass ply.

The bead portion 24 is mounted on the rim.
The rim is formed as a regular rim 11 having a regular size with which the tire fits, and the bead bottom portion 3 of the bead portion 24 is formed.
And a rim flange 13 that rises radially outward from the outer end of the rim base 12 on which the tire is seated in the tire axial direction.

A pneumatic tire 1 for a construction vehicle is mounted on a regular rim 1
In a tire meridional section A (shown in FIG. 1) in a normal internal pressure state in which the tire 1 is assembled to the rim and the tire 1 is filled with the normal internal pressure, the rim flange 13 extends from the tire axial direction outer end of the rim base 12 in the radial direction. A standing wall portion 15 having an inner surface 14 that rises outward and faces the tire 1, and the inner surface 14
Has an arcuate surface 16 that is curved outward in the tire axial direction and that is composed of an arcuate with a radius of curvature RF that locates the center of curvature Fo on the tire axial direction line XF that passes through the radially outward point C of the standing wall portion 15.

The tire 1 is in contact with the inner surface 14 of the standing wall portion 13 of the rim flange 13 as the outer surface shape from the tire maximum width point Mo which is a point on the outer surface at the tire maximum width position to the bead bottom portion 3, A bead lower surface 4 reaching an outer point C and a flange arc extending from the lower point C to a position B passing through the center of curvature Fo on the arc surface 16 of the rim flange 13 and forming an angle α with the tire axial line XF. A flange contact surface 6 consisting of an outer surface 5 is included.

The position B forming the angle α is an inner arc point B ₇₀ at an angle of 70 ° with the tire axial line XF, and
Outer arc point B where the angle with the tire axial line XF is 85 °
Exists between ₈₅ and.

Further, there is a center of curvature So on the axial line XM of the tire passing through the maximum tire width point Mo, and between the maximum tire width point Mo and the inner arc point B ₇₀ to the outer arc point B _85. The outer bulge portion 10 smoothly connecting to the flange arc outer surface 5 between the inner and outer arc points B ₇₀ and B _{85 on} the reference surface 9 formed by the arc having the radius of curvature RM.
Is attached.

Further, in this embodiment, the outer bulge portion 1
0 is the radius of curvature RR in the meridional section of the tire shown in FIG.
Has an arc surface of 1/2 to 3/2 times the radius of curvature RF of the arc surface 16 of the rim flange 13, and the maximum distance H of the outer surface of the outer bulge portion 10 from the reference line 9 is the tire section height. The range is 1.5 to 4% of TH.

Here, the tire cross-section height TH means a tire height from a base line L which is a tire axial direction line passing through a tire axial direction outer end E of the bead lower surface 4.

The outer bulge portion 10 has its contour regulated at the maximum distance from the reference line 9 so as to prevent the bulge amount from becoming excessive and the bead portion 24 from having a rigid step, and the arc surface of the rim flange 13. It is possible to prevent foreign matter from entering the interface formed by 16 and the flange contact surface 6.

The tire 1 can be formed as a radial tire in which the carcass cords are arranged in a radial arrangement or a semi-radial arrangement, and a belt layer composed of a plurality of belt plies can be provided in place of the breaker.
The present invention can be modified into various aspects.

[0026]

SPECIFIC EXAMPLE A tire having a tire size of 20.5-25 16PR and having the configuration shown in FIGS. 1 and 2 was prototyped according to the specifications shown in Table 1 (Examples 1 and 2) and its performance was tested. In addition, the tires having a conventional configuration (Comparative Example 1) and the tires having a configuration other than the configuration of the present application (Comparative Examples 2 and 3) were also tested to compare their performances. The test was conducted under the following conditions.

Rim Chafing A test tire was assembled on a regular rim and mounted on a shovel loader in a state of being filled with a regular internal pressure, and after running the vehicle for 10,000 km, it occurred on the flange contact surface of the bead portion. The presence or absence of cracks was investigated.

Rim assembly workability The difficulty of the work when assembling the rim onto a new rim and the work time thereof were judged by the feeling of the worker.
The test results are shown in Table 1.

[0029]

[Table 1]

[0030]

As described above, the tire for a construction vehicle of the present invention relates to the above-mentioned structure, and has a contact surface with a rim flange which is wider than that of a conventional tire, and has an outer surface according to the above-mentioned structure. Since the outer surface of the bead is provided with a bulge, foreign matter can be prevented from entering the interface where the outer surface of the bead contacts the inner surface of the rim flange while maintaining tire running performance and rim assembly workability. It is possible to prevent the occurrence of cracks and improve the durability, and it can be suitably used especially for an excavator loader and the like that often travels on rough terrain.

[Brief description of drawings]

FIG. 1 is a meridian sectional view of a tire showing an embodiment of the present invention together with a rim.

FIG. 2 is an enlarged cross-sectional view showing the contour of the bead portion.

FIG. 3 is a cross-sectional view showing a conventional technique.

[Explanation of symbols]

3 Bead bottom part 4 Bead bottom surface 5 Flange arc outer surface 6 Flange contact surface 7 Side outer surface 9 Reference surface 10 Outer bulge part 11 Regular rim 12 Rim base 13 Rim flange 14 Inner surface 15 Standing wall part 16 Arc surface A Tire meridional section B ₇₀ Inner arc point B ₈₅ Outer arc point C Outer point Fo Center of curvature H Maximum distance Mo Tire maximum width point RF Curvature radius RM Curvature radius RR Curvature radius So Curvature center TH Tire cross section height XF Tire axial line XM Tire axial line

Claims (2)

[Claims] 1. A tire meridional section in a state of regular internal pressure in which a regular rim is assembled to a rim and filled with a regular internal pressure, wherein a rim flange of the rim rises radially outward from a rim base and has a standing wall portion having an inner surface facing the tire. And an arcuate surface whose inner surface facing the tire is an arc of curvature radius RF whose center of curvature Fo is located on the tire axial direction line XF passing through the radially outward point C of this standing wall portion and which curves outward in the tire axial direction. And the bead lower surface reaching the outer point C by contacting the inner surface of the standing wall portion of the rim flange with the outer surface shape from the tire maximum width point Mo of the tire to the bead bottom, and from the lower point C to the rim ranging between the outer arc point B ₈₅ which forms a 85 ° arc point B ₇₀ that the angle α formed by the center of curvature Fo street tire axial direction line XF in the arcuate surface of the flange forms a 70 ° Flange contact surface consisting of a flange arc outer surface extending, and, and has a center of curvature So and the maximum tire width point Mo in the tire axial direction line on XM through the tire maximum width point Mo, from the inner arc point B ₇₀ the reference surface arc forms a radius of curvature RM inherit the range up between the outer arc point B _85, in the, the outer bulging portion continuous smoothly with the flange arc outer surface between the outer arc point B _70, B ₈₅ A pneumatic tire for a construction vehicle, comprising a side outer surface attached thereto. 2. The outer bulge portion has an arc surface whose radius of curvature is 1/2 to 3/2 times the radius of curvature RF of the arc surface of the rim flange in the meridional section of the tire, and the outer surface of the outer bulge portion is The maximum distance H from the reference line is the tire section height TH
The range is from 1.5 to 4%.
Pneumatic tire for construction vehicle as described.